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Biochimica et Biophysica Acta 1773 (2007) 78–88 www.elsevier.com/locate/bbamcr

Review Diverse functions of p120ctn in tumors ⁎ Jolanda van Hengel, Frans van Roy

Molecular Cell Biology Unit, Department for Molecular Biomedical Research, VIB-Ghent University, Technologiepark 927, B-9052 Gent (Zwijnaarde), Belgium

Received 31 May 2006; received in revised form 22 August 2006; accepted 23 August 2006 Available online 30 August 2006

Abstract

p120ctn is a member of the Armadillo family. It stabilizes the – adhesion complex at the plasma membrane, but also has additional roles in the cytoplasm and nucleus. Extensive alternative mRNA splicing and multiple phosphorylation sites generate additional complexity. Evidence is emerging that complete loss, downregulation or mislocalization of p120ctn correlates with progression of different types of human tumors. It remains to be determined whether a causal relationship exists between specific isoform expression, subcellular localization or selective phosphorylation of p120ctn on the one hand and tumor prognosis on the other. © 2006 Elsevier B.V. All rights reserved.

Keywords: Cancer progression; EMT; Cell–cell adhesion; Armadillo; Catenin; Cadherin; Rho GTPase

1. Introduction: and in cancer metastatic development must be followed by a reverse process, MET, at the site of secondary sites [12]. For instance, E-cadherin Cell–cell interactions, which are mediated by adhesion mole- expression is dynamically and reversibly modulated during cules, play vital roles in developmental morphogenesis, tissue progression of ductal breast carcinoma [13]. Reduced E-cadherin remodeling and carcinogenesis. One of the major epithelial cell– expression favors dissemination, but regaining expression favors cell adhesion molecules, E-cadherin, is frequently lost or down- survival and reattachment of metastasizing cells [13–15]. regulated in various human cancers. Reduction of its expression Brabletz et al. [14] reported that colorectal carcinomas, which correlates with the emergence of malignant characteristics, such as show E-cadherin downregulation and nuclear β-catenin at the loss of epithelial morphology, and gain of invasiveness and invasive front, reexpress E-cadherin in their metastases whereas metastatic potential [1,2]. Both reversible and irreversible mecha- β-catenin localizes to the PM and the cytoplasm. This is indicative nisms are at play. E-cadherin is somatically inactivated in diffuse- of a MET process. Recently, the term ‘metastable phenotype’,was type gastric cancer and invasive lobular breast cancer [3–5].On introduced at a recent EMT meeting in Vancouver [16]. Cells with the other hand, down-regulation of E-cadherin expression by this phenotype express both mesenchymal markers (e.g. matrix transcriptional silencing (promoter hypermethylation or expres- metalloproteinases and ) and epithelial markers (kera- sion of specific transcriptional repressors) increases cell motility tins) and show some residual E-cadherin expression. and morphological epithelial to mesenchymal transition (EMT) Although it is well known that E-cadherin is an invasion (reviewed in: [2,6–8]). For instance, the transcriptional repressors suppressor in many cancers [2], the molecular basis of this Snail1 and SIP1 are key EMT regulators [8,9] that downregulate property is poorly understood. In the past, it had been thought numerous epithelial target , including E-cadherin and that E-cadherin acts like molecular glue to inhibit cell move- many other junctional [10,11]. ments. The E-cadherin complex contains many cytoplasmic The histological similarity of secondary, metastasis-derived signaling molecules, including α-catenin and the Armadillo tumors to the primary tumor indicates that EMT-mediated (Arm) proteins β-catenin, and p120ctn. This complex has been implicated not only in cell–cell adhesion, ⁎ Correspondence author. Tel.: +32 9 33 13 601; fax: +32 9 33 13 609. but also in epithelial cell polarity, migration, growth and E-mail address: [email protected] (F. van Roy). survival. Recent studies demonstrated that the E-cadherin–β-

0167-4889/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.bbamcr.2006.08.033 J. van Hengel, F. van Roy / Biochimica et Biophysica Acta 1773 (2007) 78–88 79 catenin–α-catenin complex at the adherens junctions forms a helical conformation [28]. The proteins p120ctn, δ-catenin, dynamic rather than a stable link to the [17,18]. ARVCF, p0071, and (PKP)-1 to -3 belong to a The diverse signals emanating from the E-cadherin complex are separate subfamily of Arm proteins. The three-dimensional therefore likely to be altered by tumor-associated inactivation of structure of the Arm domain of -1 reveals nine E-cadherin, resulting in the various cancer phenotypes. instead of the originally predicted ten Arm repeats [29]. In the last two decades, the adhesive and transcriptional functions of β-catenin in human malignancies have become 3. Expression of p120ctn in various cell compartments and clear [19,20]. Tumor genetics revealed that mutations in in tumors members of the Wnt–β-catenin pathway occur in approxi- mately 90% of colorectal cancers, as well as in other cancer p120ctn associates with most if not all classical (type I) and types, such as hepatocellular carcinomas [21,22]. Mutations nonclassical (type II) cadherins [30]. p120ctn may promote that activate the Wnt–β-catenin pathway promote stabilization cell surface trafficking of cadherins through its ability to of β-catenin and induce its nuclear accumulation. This results complex with and move vesicles along in activation of gene transcription, and alteration of cell [31–33]. However, other studies indicate that p120ctn does not migration and polarity. Other mutations, e.g. in conductin or bind to the E-cadherin–catenin complex until p120ctn is in the adenomatous polyposis coli (APC) gene product, also located near or at the basolateral membrane [34]. Further, affect the degradation of β-catenin. Activating mutations in p120ctn promotes lateral clustering of cadherins [35,36], and the β-catenin gene itself have been reported in approximately regulates cadherin stability and turnover at the plasma 10% of colorectal cancer and in up to 40% of hepatocellular membrane (PM) [37–39]. It regulates the membrane traffick- carcinomas [23,24]. The role of the Arm protein p120ctn in ing route followed by E-cadherin [40]. On arrival at the plasma malignancies is less clear. membrane (PM), E-cadherin is rapidly degraded in cells that express low amounts of p120ctn [39]. Treatment of cells with 2. Structure of p120ctn isoforms lysosomal inhibitors prevents cadherin degradation in cells in which p120ctn expression is knocked down [37,38]. These The human CTNND1 gene comprises 21 exons and encodes studies indicate that p120ctn is required for retaining and potentially up to 48 protein isoforms due to many inter- and stabilizing E-cadherin molecules at the PM. The precise role of intra-exonic splicing events [25]. Human isoforms, designated 1 p120ctn in this process remains unclear. p120ctn also facilitates to 4, differ from each other in the start codon used. Alternative the recycling of cadherin back to the cell surface. Calcium switch combinations with or without internal exons A–D generate experiments have shown that p120ctn accelerates the delivery of additional isoforms [25,26]. Typical examples are isoforms cadherins to the PM via an interaction with kinesin motors 1ABC and 3AB. Several domains have been identified in [31,33]. Coupled with the growing literature on p120ctn down- p120ctn, including the coiled coil domain found only in isoform regulation in tumors of all types, these data indicate that 1, and the phosphorylation domain found in all isoforms except E-cadherin loss in at least a subset of cancers is due to prior type 4 (see Fig. 1). Isoform 1 (120-kDa or long isoform) and down-regulation of p120ctn, in addition to other well-described isoform 3 (100-kDa or short isoform) are expressed predom- mechanisms causing E-cadherin deficiency. Nonetheless, direct inantly in highly motile fibroblastoid cells and epithelial cells, evidence is lacking, and very little is known about the timing, respectively [25,27]. The Arm domain of β-catenin consists of a mechanism, or consequences of p120ctn down-regulation series of 12 linked repeats of ∼42 amino acids (aa) folded in during tumor progression.

Fig. 1. Schematic diagram of the human p120ctn protein. Multiple isoforms of p120ctn result from the use of alternative start codons (M) and alternative splicing of exons A (exon 18), B (exon 20), C (exon 11) and D (exon 4); sizes are indicated in amino acid residues (aa). p120ctn has two consensus NLS sequences and two leptomycin-B sensitive NES sequences, as indicated. The hinge region containing a NLS is also important in regulating Rho function. Approximate locations of mAb epitopes are indicated. Armadillo repeats (1 to 9) are depicted by shaded boxes. 80 J. van Hengel, F. van Roy / Biochimica et Biophysica Acta 1773 (2007) 78–88

p120ctn is also an important modulator of small Rho purified using phosphotyrosine-specific antibodies, p120ctn is a GTPases present at the adherens junctions or in the cytoplasm major phosphorylated substrate [55]. In contrast to most Src [41–43]. Rho GTPases are critical for diverse cellular functions, substrates and effectors (e.g. tensin, focal adhesion kinase, including regulation of organization, cell adhesion, cell p130CAS, p110AFAP and cortactin), the Arm protein p120ctn polarity, intracellular membrane trafficking, transcription, cell does not harbor the typical domains closely associated with cycle progression, and cell transformation [44,45]. In addition, protein kinase (PTK) signaling (e.g. tyrosine kinase domain, p120ctn interacts with Kaiso [46], which is a transcriptional SH2 or SH3 domains). Also, unlike many Src effectors, which repressor belonging to the POZ/BTB family of zinc finger can regulate the actin cytoskeleton, p120ctn is not widely proteins implicated in development and cancer [47]. considered a direct regulator of actin dynamics. On the other The various activities of p120ctn are found in different cell hand, the functions of p120ctn in cadherin-mediated adhesion compartments. Expression of p120ctn has been examined by and in Rho-GTPase modulation are consistent with the immunohistochemistry in a growing number of cancer types. In collective role of Src substrates. this review we will discuss the role of p120ctn in cancer in terms Cadherins are both necessary and sufficient for localization of its expression and localization patterns in different tumors of p120ctn to the PM and its phosphorylation by tyrosine (Fig. 2). kinases [35]. In cadherin-deficient cells, cytoplasmic p120ctn is Regional loss or down-regulation of p120ctn occurs not phosphorylated, while membrane-uncoupled Src mutants frequently in almost all human cancers (Table 1) [48]. This appear to have little access to cadherin-associated p120ctn [52]. suggests that p120ctn down-regulation in vivo may be important Thus phosphorylation of p120ctn by Src requires localization of in tumor formation or progression. Several studies have indeed both proteins at the PM, the former via cadherin binding, and found that p120ctn down-regulation is associated with poor the latter by myristoylation of its N-terminal Gly residue. patient prognosis (Table 1). Moreover, p120ctn is often found in Shibata et al. [51] showed that tyrosine-phosphorylated p120ctn the cytoplasm of tumor cells, inparticularlyinpoorly accumulates in protrusive domains of the PM. differentiated areas, but only quite rarely in the nucleus [49–51]. The role of p120ctn phosphorylation remains poorly defined. p120ctn can be phosphorylated on numerous Tyr, Ser and Thr 4. Role of p120ctn phosphorylation residues, which are mostly present in the regulatory domain [56]. The phosphorylation status of p120ctn seems to play a p120ctn is a most efficient substrate for cellular and onco- fundamental role in regulating the E-cadherin adhesion complex genic Src family tyrosine kinases [52–54]. Among the proteins [56]. Tyrosine phosphorylated p120ctn destabilizes E-cadherin/

Fig. 2. p120ctn localization in the cell changes as the cell undergo EMT. Red indicates p120ctn expression. In epithelial cells (or tumors with well differentiated epithelial cells) shorter p120ctn isoforms bind to E-cadherin present at the adherens junctions. Mesenchymal cells and tumors with poorly differentiated, highly malignant epithelial cells express mainly long p120ctn isoforms. These isoforms occur either in the cytoplasm (mesenchymal cell 1), or in both cytoplasm and nucleus (mesenchymal cell 2). Signaling pathways that are repressed by Kaiso may be relieved by the action of nuclear p120ctn. Cytoplasmic p120ctn modulates the Rho- GTPases: generally, RhoA is inactivated and Rac1 activated. Mesenchymal cells may also lose p120ctn expression completely (mesenchymal cell 3). Experimental loss of p120ctn has been reported to activate Rho while Rac-GTP levels remain unchanged. See references in the text. J. van Hengel, F. van Roy / Biochimica et Biophysica Acta 1773 (2007) 78–88 81

Table 1 p120ctn expression in tumors Organ No. of cases Absent (%) Altered (%) Clinical correlates Ref. Bladder 48 6 31% decreased or heterogeneous Correlated with poor prognosis [122] 68 84% decreased Correlated with poor prognosis [123] 102 17 70% decreased or heterogeneous No correlation [124] Breast (ILC) a 67 0 88% cytoplasmic, 6% nuclear (Ecad-neg) b NA [50] 60 0 92% cytoplasmic NA [51] Breast (IDC) c 91 10 40% Not correlated with poor prognosis [125] 80 10 58% decreased or heterogeneous Not correlated with poor prognosis [126] 195 2 60% decreased (Ecad-neg), 10% cytoplasmic NA [50] 60 92% cytoplasmic (Ecad-neg) NA [51] Colorectal 13 23 46% cytoplasmic NA [127] 20 100% decreased or heterogeneous NA [128] 44 18 68% decreased or heterogeneous Correlated with poor prognosis [129] 43 21 19% decreased or heterogeneous 25% cytoplasmic Not correlated with tumor stage [130] 557 5.4 53% cytoplasmic (Ecad-neg or cytoplasmic) Correlated with poor survival [96] Endometrial 149 64% decreased No correlation [131] Gastric 40 18 15% decreased or heterogeneous, 37% cytoplasmic Not correlated with tumor stage [130] 68 18 15% decreased or heterogeneous, 37% cytoplasmic No correlation [132] 36 56% decreased or heterogeneous No correlation [133] Gastroesophageal 96 68% decreased Correlated with poor survival [83] junction Lung 193 61% decreased or heterogeneous No correlation [134] 143 80% decreased and cytoplasmic Correlated with poor survival [97] Melanoma 67 Frequently decreased or heterogeneous No correlation [135] Pancreatic (ductal) 20 15 20% decreased or heterogeneous Not correlated with tumor stage [130] 32 100% increased, cytoplasmic and nuclear Correlated with high grade and poor survival [82] Prostate 112 49% decreased or heterogeneous Correlated with pathological stage [136] 118 45% decreased or heterogeneous Correlated with pathological stage [137] 88 30% decreased or heterogeneous (Ecad-neg) Correlated with high grade pathological stage [117] 45 22% decreased or heterogeneous NA [49] Renal 11 No significant change [138] Skin 29 48 52% decreased or heterogeneous cytoplasmic NA [139] and nuclear (Ecad-neg and +) Synovial sarcoma 15 Expression detected in all samples (Ecad-neg and +) NA [140] NA: not analyzed in this study. a ILC: invasive lobular carcinoma. b IDC: invasive ductal carcinoma. c Ecad-neg: in E-cadherin-negative cells. catenin mediated cell adhesion [57,58]. To our knowledge there tion process, as Fer interacts with cadherin indirectly through is no information about the phosphorylation status of p120ctn in p120ctn [64–66]. One function of Fer is to phosphorylate tumor samples. The commercial availability of phospho- PTP1B, which facilitates the binding of PTP1B to the cadherin specific antibodies against p120ctn can open opportunities in cytoplasmic domain and stabilizes adhesion through dephos- this respect [59,60]. One report claimed that N-cadherin phorylation of β-catenin. interacts preferentially with the long p120ctn isoforms, and Epidermal growth factor (EGF) has been shown to induce E-cadherin with the short forms [61]. In the pancreatic tumor tyrosine phosphorylation of β-catenin and plakoglobin after cell system used in this study, long p120ctn isoforms asso- association with the cadherin–catenin complex. It has been ciated with N-cadherin were found to be phosphorylated at argued that this induces disassembly of the cadherin–catenin Tyr residues, whereas the short p120ctn isoforms linked to complex from the actin filament network [67]. EGFR is E-cadherin were not. frequently overexpressed in many malignancies, and its over- Beta-catenin phosphorylation has a central role in adherens expression in primary human esophageal keratinocytes leads to junctions. Cadherin-mediated adhesions are maintained by enhanced cell migration. But at the same time it induces a shift ensuring that β-catenin remains dephosphorylated, which in the distribution of p120ctn from the cytoplasm to the requires the presence of tyrosine phosphatase activity [62]. membrane, thereby resulting in increased cell adhesion [68]. When tyrosine kinase activity is elevated, β-catenin is This example illustrates bi-directional regulation of receptor phosphorylated, cadherin-mediated adhesion is compromised, tyrosine kinases versus E-cadherin similar to that shown by and metastatic potential may increase [63]. It was shown that Qian et al. [69], who reported that E-cadherin mediated phosphorylation of β-catenin is regulated by the combined adhesion inhibits receptor tyrosine kinase activity. E-cadherin activities of the tyrosine kinase Fer and the tyrosine phosphatase was found to interact through its extracellular domain with PTP1B [64]. p120ctn is also important in this dephosphoryla- EGFR and other receptor kinases, thereby decreasing receptor 82 J. van Hengel, F. van Roy / Biochimica et Biophysica Acta 1773 (2007) 78–88 mobility and ligand affinity. In this way E-cadherin inhibits [50,51,75–77]. Two putative p120ctn nuclear localization receptor kinases, which indicates that downregulation of signals (NLS) were described: one in the phosphorylation E-cadherin may contribute to the frequently observed activation domain and one in the Arm domain. The NLS in the Arm of receptor kinases in tumors. domain has been shown to target a heterologous protein to the nucleus [78] and to influence the subcellular localization of 5. Role of p120ctn in the cytoplasm p120ctn isoform 1, although an alternate import pathway was not excluded. Deleting these NLSs [75] or mutating two Down-regulation of E-cadherin in cancer can result in positively charged Lys residues in one or both putative NLSs redistribution of p120ctn to the cytoplasm. Loss of p120ctn or (our observations) does not prevent nuclear translocation of its localization to the cytoplasm seems to alter tissue p120ctn isoform 3 in a convincing manner. This suggests that homeostasis and promote metastasis independently of its role particular p120ctn isoforms utilize different pathways for in adhesion. An example to this is that down-regulation of nucleocytoplasmic trafficking. At least for isoform 3A, the endogenous p120ctn in E-cadherin-deficient breast cancer cells nuclear import of p120ctn is dependent on the Arm domain prevented migratory phenotypes [51]. The activity of Rho [75]. This finding is consistent with data on other Arm domain GTPases is finely tuned by GTP binding and GTP hydrolysis. proteins. For instance, nuclear import of β-catenin has been Apparently, p120ctn in the cytoplasm can both down-regulate proposed to be mediated by its direct interaction with [41–43] and up-regulate active RhoA [70], and/or activate nucleoporins [79,80], although a subsequent study has Rac1. It has also been reported that p120ctn regulates Rho challenged this view [81]. On the other hand, nuclear export activity in a cell-context dependent manner [70]. Rho-GTPases signals (NES) are present in p120ctn isoforms encoding exon B regulate many cellular processes, including actin organization, (exon 20) [76] and in Arm repeat 7 (formerly named Arm repeat cell migration and cell polarity [71,72]. Several lines of 8) [75]. evidence implicate Rho family members in a variety of Nuclear immunoreactivity of p120ctn has been observed in important processes in cancer, including cell transformation, different adenocarcinomas [50,75,82,83]. Nuclear localization survival, proliferation, invasion, metastasis, and angiogenesis of p120ctn is associated mostly with its cytoplasmic localiza- [73]. p120ctn regulates Rho GTPases in vivo, as ablation of tion. Mayerle et al. [82] could not firmly distinguish by p120ctn in the epidermis and its appendages was associated immunohistochemistry between cytosolic and nuclear localiza- with a marked increase in active RhoA even though total RhoA tion of p120ctn in human pancreatic cancers, so they performed levels remained unchanged [74]. No obvious differences were immuno-electron microscopy studies. They confirmed abun- detected in the Rac1 and Cdc42 GTP pulldown assays on these dant cytosolic localization and also nuclear import of p120ctn in tissues. Similarly, knockdown of cytoplasmic p120ctn by RNA tumor cells, particularly in high-grade undifferentiated tumors. interference in a human breast cancer cell line did increase We also stained series of different types of tumors, but nuclear levels of active Rho-GTP, whereas levels of Rac-GTP remained p120ctn was never as prominent as nuclear β-catenin (our unchanged [51]. Until now no direct link between cytoplasmic unpublished data). Checking various photographs of p120ctn p120ctn and alteration in Rho-GTPases levels in tumors has staining in published articles revealed similar results. been reported. Kaiso is a ubiquitously expressed transcription factor with An association of p120ctn with microtubules has been a BTB/POZ structure (broad complex, Tramtrack, Bric a reported recently [32,75]. Mutation of particular Ser residues brac/pox virus and zinc finger). It was originally identified in within the Arm repeat domain of p120ctn to Ala (mutant AAA- a yeast two-hybrid screen for binding partners of p120ctn p120ctn) promotes association of p120ctn with interphase [46]. Kaiso demonstrates bi-modal DNA-binding activity: it microtubules [32]. Localization to the microtubules also binds methylated CpG dinucleotides or a sequence-specific depends on a Lys-rich motif in the Arm domain. In addition, consensus Kaiso binding site [84,85]. Several cancer-related AAA-p120ctn localizes to the mitotic spindle and centrosomes. gene fragments, such as regulatory sequences of the genes Rb, In the breast cancer cell line MDA-MB-231 a fraction of Xist, S100A4 (mts-1), CDH1 (E-cadherin), matrilysin (MMP7), endogenous p120ctn was detected at the centrosomes or the MTA2 (metastasis-associated gene 2) and Wnt11, have been pericentrosomal region. The mutant AAA-p120ctn did not proposed as possible sites to which Kaiso binds to repress activate Rac and did not induce the dendritic morphology, transcription [84–87]. Most interesting is the report by Park et al. typical of Rho inactivation upon WT p120ctn overexpression. [88] that Kaiso works in conjunction with T-cell factor (TCF) in As the binding of p120ctn to the microtubules and its ability to repressing known canonical Wnt target genes, at least in Xeno- activate Rac are mutually exclusive, an inverse relationship pus laevis. In this system, p120ctn was clearly shown to relieve between the two activities was proposed [32]. Kaiso-mediated transcriptional repression. On the other hand, the rapsyn core promoter was recently shown to be up-regulated 6. Role of p120ctn in the nucleus by a complex of Kaiso with δ-catenin in subsynaptic nuclei of neuromuscular junctions [89]. Although we detected p120ctn In addition to its roles in cadherin-mediated adhesion and and Kaiso separately in the nucleus, we were unable to detect regulation of Rho family GTPases, p120ctn has also been found their colocalization there [49]. In contrast, the presence of both in the nucleus. In E-cadherin deficient cell lines, p120ctn is proteins in the cytoplasm was evident in various tumors. It is frequently observed both in the cytoplasm and in the nucleus conceivable that Kaiso is retained in the cytoplasm or excluded J. van Hengel, F. van Roy / Biochimica et Biophysica Acta 1773 (2007) 78–88 83 from the nucleus by its interaction with cytoplasmic p120ctn. It isoforms is regulated at the level of transcript maturation rather has been shown that nuclear p120ctn relieves Kaiso-mediated than stability. transcriptional repression in cultured cells, but NLS-defective Likewise, Sarrio et al. [50] reported that expression of Snail, p120ctn does not [78]. The common cytoplasmic location of E47 or Slug in MDCK cells provokes p120ctn cytoplasmic p120ctn and Kaiso in vivo could mean that p120ctn inhibits localization and isoform switching. Longer and shorter p120ctn Kaiso transcriptional repression by dissociating it from the isoforms were also inversely regulated during a SIP1/ZEB2- DNA, followed by nuclear export of the p120ctn/Kaiso complex induced EMT-like process in human epithelial cancer cell lines and its sequestration in the cytoplasm, rather than by directly [10]. Up-regulation of p120ctn isoform 1 and down-regulation blocking its binding to DNA in the nucleus [47]. Kaiso of isoform 3 during EMT indicate that different isoforms may relocalization may contribute to tumor progression, but this have specific roles in epithelial versus mesenchymal states. needs to be investigated extensively. Nonetheless, a p120ctn isoform switch is not always seen The phenotype of Kaiso-deficient mice provides some during EMT. For example, no isoform switch was observed in a support for Kaiso's putative role in tumorigenesis. Kaiso-null recent study of EMT in highly differentiated colon carcinoma mice were viable, fertile, and had no detectable abnormalities in cells treated with TGF-β and TNF-α [96]. Recently, Wang et al. development or gene expression [90]. However, these mice are [97] reported abnormal expression of p120ctn in lung squamous somewhat more resistant to intestinal tumorigenesis when bred cell carcinoma and adenocarcinoma. Expression of long and onto an APCMin/+genetic background. Min mice are heterozy- short isoforms in normal lung and tumor lung tissue was gous for a mutation that truncates Apc (the adenomatous detected by Western blot analysis. Both long and short isoforms polyposis coli gene) and are a model for human familial were reduced in tumor tissues. Most other analyses of p120ctn adenomatous polyposis. The Apc mutation results in the isoforms published to date deal with tumor cell lines rather than stabilization of β-catenin, thereby promoting activation of the original tumor specimens, although immunohistochemical canonical Wnt pathway. This observation is in line with models analysis of the latter using isoform-specific antibodies could of cancer progression in which methyl-CpG-associating be most instructive. transcriptional repressors such as MBD2 or Kaiso (or Kaiso- The shorter p120ctn isoforms have been reported to like proteins) reduce the expression of gene products that would preferentially interact with E-cadherin in the pancreatic tumor normally counter tumor formation. Surprisingly, no difference cell line MIA PaCa-2, whereas the longer isoform 1 interacts in expression of four reported Kaiso target genes (S100A4, with N-cadherin [61]. However, working in several tumor cell Mta2, Rapsyn, and Wnt11) were found in the Kaiso-null mice. systems, other researchers could not reproduce this isoform This indicates that there is some redundancy in the control of preference for particular cadherin types [98,99] (K. Johnson, these genes, and that other Kaiso target genes may be involved personal communication). In several cancer types, including in the tumor phenotype. It is also not clear whether association melanoma, prostate and breast cancer, loss of E-cadherin of p120ctn with Kaiso plays a role in promoting tumors caused function is accompanied by de novo expression of mesenchy- by Apc mutations. mal cadherins, such as N-cadherin and cadherin-11 [100,101]. N-cadherin has been shown to promote cell motility and 7. Isoform switches for p120ctn and cadherins in cancer migration, which is opposite to the effect of E-cadherin [102,103]. Different types of cadherins may regulate cell It was observed that the 100-kDa (short) and 120-kDa (long) movements by controlling the levels of p120ctn present in the isoforms (see Fig 1) are expressed predominantly in, respec- cytoplasmic pool. E-cadherin appears to bind p120ctn more tively, epithelial cells and highly motile fibroblastoid cells tightly than N-cadherin [104]. Coimmunoprecipitation experi- [25,27]. Monoclonal antibodies 2B12, 5A7 and 6H11 recognize ments showed that p120ctn binds somewhat more efficiently to the longer isoforms specifically [91]. A shift from short to long VE-cadherin than to N-cadherin [105]. On the other hand, p120ctn isoform expression was seen in FosER cells, in which P-cadherin appears to have a lower affinity than N-cadherin for EMT is induced as a consequence of the activation of a cFos- p120ctn [106]. However, affinity studies on p120ctn binding estrogen receptor fusion protein by the addition of estradiol using surface plasmon resonance measurements have not been [92]. A similar reduction in the amount of the 100-kDa forms published. Overexpression of P-cadherin is strongly associated and an increase in the longer isoforms was seen in anaplastic with cytoplasmic accumulation of p120ctn and activation of the thyroid carcinoma cell lines [93], and in prostate carcinoma cell Rho-GTPases Rac1 and Cdc42 [106]. This implies that a lines [94]. cadherin switch, which may also induce a p120ctn isoform Various EMT-inducing transcriptional repressors (Snail, switch, may be involved in tumor progression. E47, Slug, SIP1/ZEB2) can induce p120ctn isoform switches. In the p120ctn-deficient cell line SW48, reconstitution of In MDCK epithelial cells, Snail-induced EMT causes striking cell–cell adhesion by p120ctn isoform 4 causes significantly transition from the “epithelial” to the “mesenchymal” p120ctn better rescue of epithelial morphology than p120ctn isoforms 1 isoform pattern [95], consistent with a motility/invasion role for and 3, indicating that the amino-terminal sequence has some the longer isoform 1. The p120ctn isoform switch is not negative effect on cell–cell adhesion [39]. This phenomenon reversed by re-expression of E-cadherin, indicating that the was also seen in Colo205 cells, which express all members of effect is Snail-induced and not directly caused by E-cadherin the cadherin complex. Their epithelial morphology is efficiently down-regulation. It also means that the expression of p120ctn rescued by an amino-terminally truncated mutant (similar to 84 J. van Hengel, F. van Roy / Biochimica et Biophysica Acta 1773 (2007) 78–88 isoform 4), but not at all by isoforms 1 and 3 [107]. Therefore, semitransformed human mammary epithelial cells yielded p120ctn-mediated stabilization of cadherins may not be δ-catenin as one of the eight strongest candidates able to sufficient by itself to achieve strong cell–cell adhesion. As suppress anchorage-independent growth [118]. the longer isoforms can readily stabilize cadherins, signaling, presumably through the N-terminal end of p120ctn, can 9. p120ctn knockout studies in mouse apparently block cell–cell adhesion despite this stabilization. Finally, p120ctn isoform switches could explain why Kaiso To examine the in vivo consequence of p120ctn ablation, was coprecipitated efficiently by p120ctn from several epithelial Davis and Reynolds [119] conditionally ablated p120ctn in cell lines but inefficiently by p120ctn from fibroblasts [46]. mice, either in the embryonic salivary gland or in the epithelia of the small intestine and colon. Moreover, in collaboration with 8. Are other p120ctn family members involved in cancer? E. Fuchs and colleagues, they ablated p120ctn in the epidermis [74]. Morphological and adhesive defects were present in most In mammals, p120ctn has three close family members of the p120ctn-null tissues, and E-cadherin expression was (ARVCF, delta-catenin and p0071), which have at least partly strongly reduced but not completely blocked. It is important to redundant functions. Indeed, each of them can interact with check whether other p120ctn family members can compensate classic cadherins through its Arm domain, and ARVCF and δ- for this ablation and stabilize E-cadherin expression to some catenin can rescue cadherin stability in vitro in p120ctn- extent. Total p120ctn knockout in mice is embryonically lethal deficient cell lines [37,108]. These proteins share >45% amino at early stage [119]. acid sequence identity in their Arm-repeat domains. Another p120ctn ablation in the submandibular gland induced group in the p120ctn family shares ∼30% identity with the dysplasia, cell shedding and epithelial masses that retained the p120ctn Arm-repeat domain and does not interact with classical ability to proliferate and escape apoptosis [119].These cadherins. In this second group, PKP 1, 2 and 3 localize to manifestations, in combination with defects in epithelial desmosomes, as well as to the cytoplasm and nucleus [109]. morphology and adhesion, are indistinguishable from high- PKP3 is reportedly elevated in non-small cell lung grade intraepithelial neoplasia, a precancerous condition that in carcinomas [110]. Another study analyzed the subcellular man usually progresses to invasive cancer. Mice lacking localization of the three PKPs and p0071 in oropharyngeal p120ctn in the epidermis show hyperproliferation of the squamous cell carcinomas [111]. PKP1 and PKP3 immunore- epidermis as well as an inflammatory response due to activation activity was inversely correlated with tumor histological grade, of NFκB [74]. This response could be relevant to understanding and it was observed only in oropharyngeal tumors that did not why loss or reduced activity of p120ctn has been correlated with metastasize. In contrast, strong PKP2 immunoreactivity was inflammatory bowel disease, particularly active ulcerative observed in most metastatic tumors. The data indicate that colitis and active Crohn's disease [120], which are known to cytoplasmic versus membranous localization of the individual predispose intestinal tissue to cancer [121]. More p120ctn PKPs has prognostic value. Because the nuclear functions of knockout studies in combination with mouse tumor models these proteins have not yet been identified, the significance of might reveal much about the complex role of p120ctn in cancer. immunoreactivity of the different proteins in the cytoplasm and/ or nucleus requires further investigation. 10. Conclusions and future directions Delta-catenin was initially identified as a presenilin-binding protein [112,113] and as a neuronal adhesive junction- Many advances have been made in understanding the roles associated protein that is expressed primarily in the brain of p120ctn in cancer. Animal models seem to confirm the [114]. Other studies showed weak expression of δ-catenin in causative roles of p120ctn in different diseases, including other organs, such as the pancreas and retina [112,115]. Delta- cancer, as had been indicated by earlier studies on cancer cell catenin expression might be closely associated with cancer, as lines. However, many important unanswered questions remain. indicated by enhanced δ-catenin transcription in prostate cancer What are the consequences of alternative splicing of p120ctn compared with benign prostate hyperplasia [116]. In a recent and how is it regulated? How is the promoter (or promoters) of study of primary prostate adenocarcinomas, examination of the the various p120ctn transcripts regulated? Do p120ctn muta- same tumor cell clusters using consecutive sections showed that tions or LOH occur in tumors? Why have no cell lines lacking increased δ-catenin immunoreactivity was accompanied by p120ctn expression been identified so far? Does cytoplasmic or down-regulation and redistribution of E-cadherin and p120ctn, nuclear p120ctn play a decisive role in tumorigenesis or tumor especially in tumors with poor prognosis [117]. It is important to progression? determine whether δ-catenin expression precedes or follows It is necessary to correlate the expression and localization p120ctn and E-cadherin down-regulation, and whether the same patterns of p120ctn with E-cadherin expression patterns, tumor inverse correlation holds for other tumor types. In addition, it is stage, metastatic property and patient survival. A significant start not junctional δ-catenin that compensates for loss of junctional has been made in this direction [50,51,96], but more studies are E-cadherin and p120ctn, because all three proteins, including needed, and it will also become important to use isoform- δ-catenin, localize in the cytoplasm when δ-catenin levels are specific antibodies for p120ctn on human tumor samples. increased [117]. On the other hand, in a search for candidate Comprehensive analysis of expression levels and localization of tumor suppressor genes, a recent siRNA-based screen on representative cadherins, Armadillo proteins, and both J. van Hengel, F. van Roy / Biochimica et Biophysica Acta 1773 (2007) 78–88 85 regulator and effector gene products of cadherins and catenins E-cadherin, alpha-catenin and beta-catenin, but not of gamma-catenin, in – might reveal the relevant signaling pathways in particular metastatic tissue from breast cancer patients, J. Pathol. 190 (2000) 15 19. [16] J.M. Lee, S. Dedhar, R. Kalluri, E.W. Thompson, The epithelial– tumor types, and open opportunities for the development of mesenchymal transition: new insights in signaling, development, and effective targeted therapies. disease, J. Cell Biol. 172 (2006) 973–981. [17] F. Drees, S. Pokutta, S. Yamada, W.J. Nelson, W.I. Weis, Alpha-catenin is Acknowledgments a molecular switch that binds E-cadherin-beta-catenin and regulates actin- filament assembly, Cell 123 (2005) 903–915. [18] S. Yamada, S. Pokutta, F. Drees, W.I. Weis, W.J. Nelson, Deconstructing J.v.H. is a postdoctoral fellow with the FWO (National Fund the cadherin–catenin–actin complex, Cell 123 (2005) 889–901. for Scientific Research-Flanders). This research has been [19] C.Y. Logan, R. Nusse, The in development and funded by grants from the FWO, Geconcerteerde Onderzoek- disease, Annu. Rev. Cell Dev. Biol. 20 (2004) 781–810. sacties of Ghent University, Interuniversity Attraction Poles [20] T. Reya, H. Clevers, Wnt signalling in stem cells and cancer, Nature 434 – Programme of the Belgian Science Policy, Belgian Federation (2005) 843 850. [21] B. Vogelstein, K.W. Kinzler, Cancer genes and the pathways they control, against Cancer, and FP6 of the European Union (BRECOSM). Nat. Med. 10 (2004) 789–799. We acknowledge Dr. A. Bredan for critical reading of the [22] M. Bienz, H. Clevers, Linking colorectal cancer to Wnt signaling, Cell manuscript. 103 (2000) 311–320. [23] P.J. Morin, A.B. Sparks, V. Korinek, N. Barker, H. Clevers, B. Vogelstein, K.W. Kinzler, Activation of beta-catenin-Tcf signalling in colon cancer References by mutations in beta-catenin or APC, Science 275 (1997) 1787–1789. [24] P. Legoix, O. Bluteau, J. Bayer, C. Perret, C. Balabaud, J. Belghiti, D. [1] G. Berx, F. Van Roy, The E-cadherin/catenin complex: an important Franco, G. Thomas, P. Laurent-Puig, J. Zucman-Rossi, Beta-catenin gatekeeper in breast cancer tumorigenesis and malignant progression, mutations in hepatocellular carcinoma correlate with a low rate of loss of Breast Cancer Res. 3 (2001) 289–293. heterozygosity, Oncogene 18 (1999) 4044–4046. [2] K. Strumane, G. Berx, F. van Roy, Cadherins in cancer, in: J. Behrens, J. [25] A. Keirsebilck, S. Bonné, K. Staes, J. van Hengel, F. Nollet, A. Reynolds, Nelson (Eds.), Cell adhesion, Springer-Verlag, Heidelberg, Germany, F. van Roy, Molecular cloning of the human p120ctn catenin gene 2004, pp. 69–103. (CTNND1): expression of multiple alternatively spliced isoforms, [3] G. Berx, A.-M. Cleton-Jansen, F. Nollet, W.J.F. de Leeuw, M.J. van de Genomics 50 (1998) 29–146. Vijver, C. Cornelisse, F. van Roy, E-cadherin is a tumor/invasion [26] S. Aho, K. Rothenberger, J. Uitto, Human (Ctn) catenin: Tissue- suppressor gene mutated in human lobular breast cancers, EMBO J. 14 specific expression of isoforms and molecular interactions with BP180 (1995) 6107–6115. type XVII collagen, J. Cell. Biochem. 73 (1999) 390–399. [4] K.F. Becker, M.J. Atkinson, U. Reich, I. Becker, H. Nekarda, J.R. [27] Y.Y. Mo, A.B. Reynolds, Identification of murine p120(cas) isoforms and Siewert, H. Höfler, E-cadherin gene mutations provide clues to diffuse heterogeneous expression of p120(cas) isoforms in human tumor cell type gastric carcinomas, Cancer Res. 54 (1994) 3845–3852. lines, Cancer Res. 56 (1996) 2633–2640. [5] G. Berx, K.-F. Becker, H. Höfler, F. van Roy, Mutation update: mutations [28] A.H. Huber, W.J. Nelson, W.I. Weis, Three-dimensional structure of the of the human E-cadherin (CDH1) gene, Human Mutat. 12 (1998) region of beta-catenin, Cell 90 (1997) 871–882. 226–237. [29] H.J. Choi, W.I. Weis, Structure of the armadillo repeat domain of [6] H.C. Peinado, F. Portillo, A. Cano, Transcriptional regulation of plakophilin 1, J. Mol. Biol. 346 (2005) 367–376. cadherins during development and carcinogenesis, Int. J. Dev. Biol. 48 [30] A.B. Reynolds, J.M. Daniel, Y.-Y. Mo, J. Wu, Z. Zhang, The novel (2004) 365–375. catenin p120cas binds classical cadherins and induces an unusual [7] G. Berx, F. van Roy, Epithelial cell plasticity by dynamic transcriptional morphological phenotype in NIH3T3 fibroblasts, Exp. Cell Res. 225 regulation of E-cadherin, in: P. Savagner (Ed.), Rise and Fall of Epithelial (1996) 328–337. Phenotype (ISBN 1-58706-276-3)- Chapter 11, Eurekah.com and Kluwer [31] X. Chen, S. Kojima, G.G. Borisy, K.J. Green, p120 catenin associates Academic/Plenum Publishers, 2004, pp. 1–13. with kinesin and facilitates the transport of cadherin–catenin complexes [8] B. De Craene, F. van Roy, G. Berx, Unraveling signalling cascades for the to intercellular junctions, J. Cell Biol. 163 (2003) 547–557. Snail family of transcription factors, Cell. Signal. 17 (2005) 535–547. [32] C.M. Franz, A.J. Ridley, p120 catenin associates with microtubules— [9] A. Barrallo-Gimeno, M.A. Nieto, The Snail genes as inducers of cell Inverse relationship between binding and Rho GTPase movement and survival: implications in development and cancer, regulation, J. Biol. Chem. 279 (2004) 6588–6594. Development 132 (2005) 3151–3161. [33] M. Yanagisawa, I.N. Kaverina, A.X. Wang, Y. Fujita, A.B. Reynolds, P.Z. [10] C. Vandewalle, J. Comijn, B. De Craene, P. Vermassen, E. Bruyneel, H. Anastasiadis, A novel interaction between kinesin and p120 modulates Andersen, E. Tulchinsky, F. van Roy, G. Berx, SIP1/ZEB2 induces EMT p120 localization and function, J. Biol. Chem. 279 (2004) 9512–9521. by repressing genes of the different epithelial cell–cell junctions, Nucleic [34] K.C. Miranda, S.R. Joseph, A.S. Yap, R.D. Teasdale, J.L. Stow, Acids Res. 33 (2005) 6566–6578. Contextual binding of p120(Ctn) to E-cadherin at the basolateral [11] B. De Craene, B. Gilbert, C. Stove, E. Bruyneel, F. van Roy, G. Berx, The plasma membrane in polarized epithelia, J. Biol. Chem. 278 (2003) transcription factor Snail induces tumor cell invasion through modulation 43480–43488. of the epithelial cell differentiation program, Cancer Res. 65 (2005) [35] M.A. Thoreson, P.Z. Anastasiadis, J.M. Daniel, R.C. Ireton, M.J. 6237–6244. Wheelock, K.R. Johnson, D.K. Hummingbird, A.B. Reynolds, Selective [12] J.P. Thiery, J.P. Sleeman, Complex networks orchestrate epithelial– uncoupling of p120ctn from E-cadherin disrupts strong adhesion, J. Cell mesenchymal transitions, Nat. Rev., Mol. Cell Biol. 7 (2006) 131–142. Biol. 148 (2000) 189–201. [13] P.J. Kowalski, M.A. Rubin, C.G. Kleer, E-cadherin expression in primary [36] A.S. Yap, C.M. Niessen, B.M. Gumbiner, The juxtamembrane region of carcinomas of the breast and its distant metastases, Breast Cancer Res. 5 the cadherin cytoplasmic tail supports lateral clustering, adhesive (2003) R217–R222. strengthening, and interaction with p120ctn, J. Cell Biol. 141 (1998) [14] T. Brabletz, A. Jung, S. Reu, M. Porzner, F. Hlubek, L.A. Kunz- 779–789. Schughart, R. Knuechel, T. Kirchner, Variable beta-catenin expression in [37] M.A. Davis, R.C. Ireton, A.B. Reynolds, A core function for p120- colorectal cancers indicates tumor progression driven by the tumor catenin in cadherin turnover, J. Cell Biol. 163 (2003) 525–534. environment, Proc. Natl. Acad. Sci. U. S. A. 98 (2001) 10356–10361. [38] K.Y. Xiao, D.F. Allison, K.M. Buckley, M.D. Kottke, P.A. Vincent, V. [15] I.K. Bukholm, J.M. Nesland, A.L. Borresen-Dale, Re-expression of Faundez, A.P. Kowalczyk, Cellular levels of p120 catenin function as a 86 J. van Hengel, F. van Roy / Biochimica et Biophysica Acta 1773 (2007) 78–88

set point for cadherin expression levels in microvascular endothelial cells, [60] X. Xia, J. Brooks, R. Campos-Gonzalez, A.B. Reynolds, Serine and J. Cell Biol. 163 (2003) 535–545. threonine phospho-specific antibodies to p120-catenin, Hybrid. Hybri- [39] R.C. Ireton, M.A. Davis, J. van Hengel, D.J. Mariner, K. Barnes, M.A. domics 23 (2004) 343–351. Thoreson, P.Z. Anastasiadis, L. Matrisian, L.M. Bundy, L. Sealy, B. [61] B. Seidel, S. Braeg, G. Adler, D. Wedlich, A. Menke, E- and N-cadherin Gilbert, F. van Roy, A.B. Reynolds, A novel role for p120 catenin in differ with respect to their associated p120(Ctn) isoforms and their ability E-cadherin function, J. Cell Biol. 159 (2002) 465–476. to suppress invasive growth in pancreatic cancer cells, Oncogene 23 [40] M. Peifer, A.S. Yap, Traffic control: p120-catenin acts as a gatekeeper to (2004) 5532–5542. control the fate of classical cadherins in mammalian cells, J. Cell Biol. [62] J. Lilien, J. Balsamo, C. Arregui, G. Xu, Turn-off, drop-out: functional 163 (2003) 437–440. state switching of cadherins, Dev. Dyn. 224 (2002) 18–29. [41] P.Z. Anastasiadis, S.Y. Moon, M.A. Thoreson, D.J. Mariner, H.C. [63] J. Lilien, J. Balsamo, The regulation of cadherin-mediated adhesion by Crawford, Y. Zheng, A.B. Reynolds, Inhibition of RhoA by p120 catenin, tyrosine phosphorylation/dephosphorylation of beta-catenin, Curr. Opin. Nat. Cell Biol. 2 (2000) 637–644. Cell Biol. 17 (2005) 459–465. [42] N.K. Noren, B.P. Liu, K. Burridge, B. Kreft, p120 catenin regulates the [64] G. Xu, A.W.B. Craig, P. Greer, M. Miller, P.Z. Anastasiadis, J. Lilien, J. actin cytoskeleton via Rho family GTPases, J. Cell Biol. 150 (2000) Balsamo, Continuous association of cadherin with beta-catenin re- 567–579. quires the non-receptor tyrosine-kinase Fer, J. Cell. Sci. 117 (2004) [43] I. Grosheva, M. Shtutman, M. Elbaum, A.D. Bershadsky, p120 catenin 3207–3219. affects cell motility via modulation of activity of Rho-family GTPases: a [65] L. Kim, T.W. Wong, The cytoplasmic tyrosine kinase FER is associated link between cell–cell contact formation and regulation of cell loco- with the catenin-like substrate pp120 and is activated by growth factors, motion, J. Cell. Sci. 114 (2001) 695–707. Mol. Cell. Biol. 15 (1995) 4553–4561. [44] M. Fukata, M. Nakagawa, K. Kaibuchi, Roles of Rho-family GTPases in [66] J. Piedra, S. Miravet, J. Castano, H.G. Palmer, N. Heisterkamp, A.G. cell polarisation and directional migration, Curr. Opin. Cell Biol. 15 deHerreros, M. Dunach, p120 catenin-associated Fer and Fyn tyrosine (2003) 590–597. kinases regulate beta-catenin Tyr-142 phosphorylation and beta-catenin– [45] S. Etienne-Manneville, Cdc42—The centre of polarity, J. Cell. Sci. 117 alpha-catenin interaction, Mol. Cell. Biol. 23 (2003) 2287–2297. (2004) 1291–1300. [67] H. Hoschuetzky, H. Aberle, R. Kemler, Beta-catenin mediates the [46] J.M. Daniel, A.B. Reynolds, The catenin p120(Ctn) interacts with Kaiso, interaction of the cadherin catenin complex with epidermal growth factor a novel BTB/POZ domain zinc finger transcription factor, Mol. Cell. receptor, J. Cell Biol. 127 (1994) 1375–1380. Biol. 19 (1999) 3614–3623. [68] C.D. Andl, T. Mizushima, H. Nakagawa, K. Oyama, H. Harada, K. [47] F.M. van Roy, P.D. McCrea, A role for Kaiso–p120ctn complexes in Chruma, M. Herlyn, A.K. Rustgi, Epidermal growth factor receptor cancer? Nat. Rev., Cancer 5 (2005) 956–964. mediates increased cell proliferation, migration, and aggregation in [48] M.A. Thoreson, A.B. Reynolds, Altered expression of the catenin p120 in esophageal keratinocytes in vitro and in vivo, J. Biol. Chem. 278 (2003) human cancer: implications for tumor progression, Differentiation 70 1824–1830. (2002) 583–589. [69] X.L. Qian, T. Karpova, A.M. Sheppard, J. McNally, D.R. Lowy, [49] A. Soubry, J. van Hengel, E. Parthoens, C. Colpaert, E. Van Marck, D. E-cadherin-mediated adhesion inhibits ligand-dependent activation of Waltregny, A. Reynolds, F. van Roy, Expression and nuclear location of diverse receptor tyrosine kinases, EMBO J. 23 (2004) 1739–1748. the transcriptional repressor Kaiso is regulated by the tumor microenvi- [70] M. Cozzolino, V. Stagni, L. Spinardi, N. Campioni, C. Fiorentini, E. ronment, Cancer Res. 65 (2005) 2224–2233. Salvati, S. Alema, A.M. Salvatore, p120 catenin is required for growth [50] D. Sarrio, B. Perez-Mies, D. Hardisson, G. Moreno-Bueno, A. Suarez, A. factor-dependent cell motility and scattering in epithelial cells, Mol. Biol. Cano, J. Martin-Perez, C. Gamallo, J. Palacios, Cytoplasmic localization Cell 14 (2003) 1964–1977. of p120ctn and E-cadherin loss characterize lobular breast carcinoma [71] S. Etienne-Manneville, A. Hall, Rho GTPases in cell biology, Nature 420 from preinvasive to metastatic lesions, Oncogene 23 (2004) 3272–3283. (2002) 629–635. [51] T. Shibata, A. Kokubu, S. Sekine, Y. Kanai, S. Hirohashi, Cytoplasmic [72] A. Hall, Rho GTPases and the actin cytoskeleton, Science 279 (1998) p120ctn regulates the invasive phenotypes of E-cadherin-deficient breast 509–514. cancer, Am. J. Pathol. 164 (2004) 2269–2278. [73] E. Sahai, C.J. Marshall, Rho-GTPases and cancer, Nat. Rev., Cancer 2 [52] A.B. Reynolds, D.J. Roesel, S.B. Kanner, J.T. Parsons, Transformation- (2002) 133–142. specific tyrosine phosphorylation of a novel cellular protein in chicken [74] M. Perez-Moreno, M.A. Davis, E. Wong, H.A. Pasolli, A.B. Reynolds, E. cells expressing oncogenic variants of the avian cellular src gene, Mol. Fuchs, p120-Catenin mediates inflammatory responses in the skin, Cell Cell. Biol. 9 (1989) 629–638. 124 (2006) 631–644. [53] E. Calautti, S. Cabodi, P.L. Stein, M. Hatzfeld, N. Kedersha, G.P. Dotto, [75] A. Roczniak-Ferguson, A.B. Reynolds, Regulation of p120-catenin Tyrosine phosphorylation and Src family kinases control keratinocyte nucleocytoplasmic shuttling activity, J. Cell. Sci. 116 (2003) 4201–4212. cell–cell adhesion, J. Cell Biol. 141 (1998) 1449–1465. [76] J. van Hengel, P. Vanhoenacker, K. Staes, F. van Roy, Nuclear [54] D.J. Mariner, P. Anastasiadis, H. Keilhack, F.D. Bohmer, J. Wang, A.B. localization of the p120ctn Armadillo-like catenin is counteracted by a Reynolds, Identification of Src phosphorylation sites in the catenin nuclear export signal and by E-cadherin expression, Proc. Natl. Acad. p120ctn, J. Biol. Chem. 276 (2001) 28006–28013. Sci. U. S. A. 96 (1999) 7980–7985. [55] S.B. Kanner, A.B. Reynolds, R.R. Vines, J.T. Parsons, Monoclonal [77] A. Ferber, C. Yaen, E. Sarmiento, J. Martinez, An octapeptide in the antibodies to individual tyrosine-phosphorylated protein substrates of juxtamembrane domain of VE-cadherin is important for p120ctn binding oncogene-encoded tyrosine kinases, Proc. Natl. Acad. Sci. U. S. A. 87 and cell proliferation, Exp. Cell Res. 274 (2002) 35–44. (1990) 3328–3332. [78] K.F. Kelly, C.M. Spring, A.A. Otchere, J.M. Daniel, NLS-dependent [56] A.B. Reynolds, A. Roczniak-Ferguson, Emerging roles for p120-catenin nuclear localization of p120ctn is necessary to relieve Kaiso-mediated in cell adhesion and cancer, Oncogene 23 (2004) 7947–7956. transcriptional repression, J. Cell. Sci. 117 (2004) 2675–2786. [57] M.S. Kinch, G.J. Clark, C.J. Der, K. Burridge, Tyrosine phosphorylation [79] F. Fagotto, U. Gluck, B.M. Gumbiner, Nuclear localization signal- regulates the adhesions of ras-transformed breast epithelia, J. Cell Biol. independent and importin karyopherin-independent nuclear import of 130 (1995) 461–471. beta-catenin, Curr. Biol. 8 (1998) 181–190. [58] M. Ozawa, T. Ohkubo, Tyrosine phosphorylation of p120(Ctn) in v-Src [80] F. Yokoya, N. Imamoto, T. Tachibana, Y. Yoneda, Beta-catenin can be transfected L cells depends on its association with E-cadherin and reduces transported into the nucleus in a Ran-unassisted manner, Mol. Biol. Cell adhesion activity, J. Cell. Sci. 114 (2001) 503–512. 10 (1999) 1119–1131. [59] D.J. Mariner, M.A. Davis, A.B. Reynolds, EGFR signaling to p120- [81] E.K. Suh, B.M. Gumbiner, Translocation of beta-catenin into the nucleus catenin through phosphorylation at Y228, J. Cell. Sci. 117 (2004) independent of interactions with FG-rich nucleoporins, Exp. Cell Res. 1339–1350. 290 (2003) 447–456. J. van Hengel, F. van Roy / Biochimica et Biophysica Acta 1773 (2007) 78–88 87

[82] J. Mayerle, H. Friess, M.W. Buchler, J. Schnekenburger, F.U. Weiss, K.P. [100] K. Tomita, A. van Bokhoven, G. van Leenders, E.T.G. Ruijter, C.F.J. Zimmer, W. Domschke, M.M. Lerch, Up-regulation, nuclear import, and Jansen, M.J.G. Bussemakers, J.A. Schalken, Cadherin switching in tumor growth stimulation of the adhesion protein p120ctn in pancreatic human prostate cancer progression, Cancer Res. 60 (2000) 3650–3654. cancer, Gastroenterology 124 (2003) 949–960. [101] G. Li, M. Herlyn, Dynamics of intercellular communication during [83] B.P.L. Wijnhoven, M. Pignatelli, W.N.M. Dinjens, H.W. Tilanus, melanoma development, Mol. Med. Today 6 (2000) 163–169. Reduced p120(ctn) expression correlates with poor survival in patients [102] M.T. Nieman, R.S. Prudoff, K.R. Johnson, M.J. Wheelock, N-cadherin with adenocarcinorna of the gastroesophageal junction, J. Surg. Oncol. 92 promotes motility in human breast cancer cells regardless of their (2005) 116–123. E-cadherin expression, J. Cell Biol. 147 (1999) 631–643. [84] J.M. Daniel, C.M. Spring, H.C. Crawford, A.B. Reynolds, A. Baig, The [103] R.B. Hazan, G.R. Phillips, R.F. Qiao, L. Norton, S.A. Aaronson, p120(Ctn)-binding partner Kaiso is a bi-modal DNA-binding protein that Exogenous expression of N-cadherin in breast cancer cells induces cell recognizes both a sequence-specific consensus and methylated CpG migration, invasion, and metastasis, J. Cell Biol. 148 (2000) 779–790. dinucleotides, Nucleic Acids Res. 30 (2002) 2911–2919. [104] P.Z. Anastasiadis, A.B. Reynolds, Regulation of Rho GTPases by p120- [85] A. Prokhortchouk, B. Hendrich, H. Jorgensen, A. Ruzov, M. Wilm, G. catenin, Curr. Opin. Cell Biol. 13 (2001) 604–610. Georgiev, A. Bird, E. Prokhortchouk, The p120 catenin partner Kaiso is a [105] P. Navarro, L. Ruco, E. Dejana, Differential localization of VE- and DNA methylation-dependent transcriptional repressor, Genes Dev. 15 N-cadherins in human endothelial cells: VE-cadherin competes with (2001) 1613–1618. N-cadherin for junctional localization, J. Cell Biol. 140 (1998) 1475–1484. [86] H.G. Yoon, D.W. Chan, A.B. Reynolds, J. Qin, J.M. Wong, N-CoR [106] K. Taniuchi, H. Nakagawa, M. Hosokawa, T. Nakamura, H. Eguchi, F. mediates DNA methylation-dependent repression through a methyl CpG Ohigashi, O. Ishikawa, T. Katagiri, Y. Nakamura, Overexpressed binding protein Kaiso, Mol. Cell 12 (2003) 723–734. P-cadherin/CDH3 promotes motility of pancreatic cancer cells by [87] S.W. Kim, J.I. Park, C.M. Spring, A.K. Sater, H. Ji, A.A. Otchere, J.M. interacting with p120ctn and activating Rho-family GTPases, Cancer Daniel, P.D. McCrea, Non-canonical Wnt signals are modulated by the Res. 65 (2005) 3092–3099. Kaiso transcriptional repressor and p120-catenin, Nat. Cell Biol. 6 (2004) [107] S. Aono, S. Nakagawa, A.B. Reynolds, M. Takeichi, p120ctn acts as an 1212–1220. inhibitory regulator of cadherin function in colon carcinoma cells, J. Cell [88] J.-i. Park, S.-W. Kim, J.P. Lyons, H. Ji, T.T. Nguyen, K. Cho, M.C. Biol. 145 (1999) 551–562. Barton, T. Deroo, K. Vleminckx, R.T. Moon, P.D. Mcrea, Kaiso/p120- [108] M. Hatzfeld, K.J. Green, H. Sauter, Targeting of p0071 to desmosomes catenin and TCF/beta-catenin complexes coordinately regulate canonical and adherens junctions is mediated by different protein domains, J. Cell Wnt gene targets, Dev. Cell 8 (2005) 843–854 (erratum 9: 305). Sci. 116 (2003) 1219–1233. [89] M. Rodova, K.F. Kelly, M. Van Saun, J.M. Daniel, M.J. Werle, [109] A. Schmidt, S. Jager, Plakophilins—Hard work in the desmosome, Regulation of the rapsyn promoter by Kaiso and delta-catenin, Mol. recreation in the nucleus? Eur. J. Cell Biol. 84 (2005) 189–204. Cell. Biol. 24 (2004) 7188–7196. [110] C. Furukawa, Y. Daigo, N. Ishikawa, T. Kato, T. Ito, E. Tsuchiya, S. Sone, [90] A. Prokhortchouk, O. Sansom, J. Selfridge, I.M. Caballero, S. Salozhin, Y. Nakamura, Plakophilin 3 oncogene as prognostic marker and D. Aithozhina, L. Cerchietti, F.G. Meng, L.H. Augenlicht, J.M. therapeutic target for lung cancer, Cancer Res. 65 (2005) 7102–7110. Mariadason, B. Hendrich, A. Melnick, E. Prokhortchouk, A. Clarke, A. [111] S. Papagerakis, A.H. Shabana, J. Depondt, P. Gehanno, N. Forest, Bird, Kaiso-deficient mice show resistance to intestinal cancer, Mol. Cell. Immunohistochemical localization of plakophilins (PKP1, PKP2, PKP3, Biol. 26 (2006) 199–208. and p0071) in primary oropharyngeal tumors: Correlation with clinical [91] J. Wu, D.J. Mariner, M.A. Thoreson, A.B. Reynolds, Production and parameters, Hum. Pathol. 34 (2003) 565–572. characterization of monoclonal antibodies to the catenin p120(Ctn), [112] J.H. Zhou, U. Liyanage, M. Medina, C. Ho, A.D. Simmons, M. Lovett, Hybridoma 17 (1998) 175–183. K.S. Kosik, Presenilin 1 interaction in the brain with a novel member of [92] A. Eger, A. Stockinger, B. Schaffhauser, H. Beug, R. Foisner, Epithelial the Armadillo family, Neuroreport 8 (1997) 1489–1494. mesenchymal transition by c-Fos estrogen receptor activation involves [113] H. Tanahashi, T. Tabira, Isolation of human delta-catenin and its binding nuclear translocation of beta-catenin and upregulation of beta-catenin/ specificity with presenilin 1, Neuroreport 10 (1999) 563–568. lymphoid enhancer binding factor-1 transcriptional activity, J. Cell Biol. [114] S.B. Jones, G.W. Lanford, Y.H. Chen, M. Moribito, K. Kim, Q. Lu, 148 (2000) 173–187. Glutamate-induced delta-catenin redistribution and dissociation from [93] J. Husmark, N.E. Heldin, M. Nilsson, N-cadherin-mediated adhesion and postsynaptic receptor complexes, Neuroscience 115 (2002) 1009–1021. aberrant catenin expression in anaplastic thyroid-carcinoma cell lines, Int. [115] R. Paffenholz, C. Kuhn, C. Grund, S. Stehr, W.W. Franke, The arm-repeat J. Cancer 83 (1999) 692–699. protein NPRAP (Neurojungin) is a constituent of the plaques of the outer [94] N.L. Tran, R.B. Nagle, A.E. Cress, R.L. Heimark, N-cadherin expression limiting zone in the retina, defining a novel type of adhering junction, in human prostate carcinoma cell lines—An epithelial–mesenchymal Exp. Cell Res. 250 (1999) 452–464. transformation mediating adhesion with stromal cells, Am. J. Pathol. 155 [116] M.J. Burger, M.A. Tebay, P.A. Keith, H.M. Samaratunga, J. Clements, (1999) 787–798. M.F. Lavin, R.A. Gardiner, Expression analysis of delta-catenin and [95] T. Ohkubo, M. Ozawa, The transcription factor Snail downregulates the prostate-specific membrane antigen: their potential as diagnostic tight junction components independently of E-cadherin downregulation, markers for prostate cancer, Int. J. Cancer 100 (2002) 228–237. J. Cell. Sci. 117 (2004) 1675–1685. [117] Q. Lu, L.J. Dobbs, C.W. Gregory, G.W. Lanford, M.P. Revelo, S. [96] D.I. Bellovin, R.C. Bates, A. Muzikansky, D.L. Rimm, A.M. Mercurio, Shappell, Y.H. Chen, Increased expression of delta-catenin/neurat Altered localization of p120 catenin during epithelial to mesenchymal plakophilin-related armadillo protein is associated with the down- transition of colon carcinoma is prognostic for aggressive disease, Cancer regulation and redistribution of E-cadherin and p120(Ctn) in human Res. 65 (2005) 10938–10945. prostate cancer, Hum. Pathol. 36 (2005) 1037–1048. [97] E.H. Wang, Y. Liu, H.T. Xu, S.D. Dai, N. Liu, C.Y. Xie, X.M. Yuan, [118] T.F. Westbrook, E.S. Martin, M.R. Schlabach, Y. Leng, A.C. Liang, B. Abnormal expression and clinicopathologic significance of p120-catenin Feng, J.J. Zhao, T.M. Roberts, G. Mandel, G.J. Hannon, R.A. Depinho, L. in lung cancer, Histol. Histopathol. 21 (2006) 841–847. Chin, S.J. Elledge, A genetic screen for candidate tumor suppressors [98] M. Jaggi, M.J. Wheelock, K.R. Johnson, Differential displacement of identifies REST, Cell 121 (2005) 837–848. classical cadherins by VE-cadherin, Cell Adhes. Commun. 9 (2002) [119] M.A. Davis, A.B. Reynolds, Blocked acinar development, E-cadherin 103–115. reduction, and intraepithelial neoplasia upon ablation of p120-catenin in [99] M. Maeda, E. Johnson, S. Mandal, K. Lawson, S. Keim, R. Svoboda, S. the mouse salivary gland, Dev. Cell 10 (2006) 21–31. Caplan, J.r. Wahl, M. Wheelock, K. Johnson, Expression of inappropriate [120] A.J. Karayiannakis, K.N. Syrigos, J. Efstathiou, A. Valizadeh, M. Noda, cadherins by epithelial tumor cells promotes endocytosis and degradation R.J. Playford, W. Kmiot, M. Pignatelli, Expression of catenins and of E-cadherin via competition for p120(ctn), Oncogene 25 (2006) E-cadherin during epithelial restitution in inflammatory bowel disease, 4595–4604. J. Pathol. 185 (1998) 413–418. 88 J. van Hengel, F. van Roy / Biochimica et Biophysica Acta 1773 (2007) 78–88

[121] M.L. Hermiston, J.I. Gordon, Inflammatory bowel disease and adenomas [132] A.U. Jawhari, M. Noda, M. Pignatelli, M. Farthing, Up-regulated in mice expressing a dominant negative N-cadherin, Science 270 (1995) cytoplasmic expression, with reduced membranous distribution, of the 1203–1207. src substrate p120(Ctn) in gastric carcinoma, J. Pathol. 189 (1999) [122] T. Shimazui, J.A. Schalken, L.A. Giroldi, C.F.J. Jansen, H. Akaza, K. 180–185. Koiso, F.M.J. Debruyne, P.P. Bringuier, Prognostic value of cadherin- [133] G. Karatzas, A.J. Karayiannakis, K.N. Syrigos, E. Chatzigianni, S. associated molecules (alpha-, beta-, and gamma-catenins and p120cas) in Papanikolaou, G. Simatos, D. Papanikolaou, S. Bogris, Expression bladder tumors, Cancer Res. 56 (1996) 4154–4158. patterns of the E-cadherin–catenin cell–cell adhesion complex in gastric [123] K.N. Syrigos, A. Karayiannakis, E.I. Syrigou, K. Harrington, M. cancer, Hepatogastroenterology 47 (2000) 1465–1469. Pignatelli, Abnormal expression of p120 correlates with poor survival [134] R.M. Bremnes, R. Veve, E. Gabrielson, F.R. Hirsch, A. Baron, L. Bemis, in patients with bladder cancer, Eur. J. Cancer 34 (1998) 2037–2040. R.M. Gemmill, H.A. Drabkin, W.A. Franklin, High-throughput tissue [124] L. Nakopoulou, A. Zervas, H. Gakiopoulou-Givalou, C. Constantinides, microarray analysis used to evaluate biology and prognostic significance G. Doumanis, P. Davaris, C. Dimopoulos, Prognostic value of E-cadherin, of the E-cadherin pathway in non-small-cell lung cancer, J. Clin. Oncol. beta-catenin, P120(Ctn) in patients with transitional cell bladder cancer, 20 (2002) 2417–2428. Anticancer Res. 20 (2000) 4571–4578. [135] X.D. Zhang, P. Hersey, Expression of catenins and p120(Cas) in [125] D.A. Dillon, T. D'Aquila, A.B. Reynolds, E.R. Fearon, D.L. Rimm, The melanocytic nevi and cutaneous melanoma: deficient alpha-catenin expression of p120ctn protein in breast cancer is independent of alpha- expression is associated with melanoma progression, Pathology 31 and beta-catenin and E-cadherin, Am. J. Pathol. 152 (1998) 75–82. (1999) 239–246. [126] L. Nakopoulou, H. Gakiopoulou-Givalou, A.J. Karayiannakis, I. [136] B.V.S. Kallakury, C.E. Sheehan, J.S. Ross, Co-downregulation of cell Giannopoulou, A. Keramopoulos, P. Davaris, M. Pignatelli, Abnormal adhesion proteins alpha- and beta-catenins, p120CTN, E-cadherin, and alpha-catenin expression in invasive breast cancer correlates with poor CD44 in prostatic adenocarcinomas, Human Pathol. 32 (2001) patient survival, Histopathology 40 (2002) 536–546. 849–855. [127] A. Skoudy, S. Gomez, M. Fabre, A.G. de Herreros, p120-catenin [137] B.V.S. Kallakury, C.E. Sheehan, E. Winn-Deen, J. Oliver, H.A.G. Fisher, expression in human colorectal cancer, Int. J. Cancer 68 (1996) 14–20. R.P. Kaufman, J.S. Ross, Decreased expression of catenins (alpha and [128] A. Valizadeh, A.J. Karayiannakis, I. El Hariry, W. Kmiot, M. Pignatelli, beta), p120 CTN, and E-cadherin cell adhesion proteins and E-cadherin Expression of E-cadherin-associated molecules (alpha-, beta-, and gene promoter methylation in prostatic adenocarcinomas, Cancer 92 gamma-catenins and p120) in colorectal polyps, Am. J. Pathol. 150 (2001) 2786–2795. (1997) 1977–1984. [138] K. Kuroiwa, T. Konomoto, J. Kumazawa, S. Naito, M. Tsuneyoshi, [129] J.S. Gold, A.B. Reynolds, D.L. Rimm, Loss of p120ctn in human Cell proliferative activity and expression of cell–cell adhesion factors colorectal cancer predicts metastasis and poor survival, Cancer Lett. 132 (E-cadherin, alpha-, beta-, and gamma-catenin, and p120) in sarcoma- (1998) 193–201. toid renal cell carcinoma, J. Surg. Oncol. 77 (2001) 123–131. [130] A.J. Karayiannakis, K.N. Syrigos, D. Alexiou, N. Kalahanis, T. [139] Y. Ishizaki, Y. Omori, M. Momiyama, Y. Nishikawa, T. Tokairin, M. Rosenberg, E. Bastounis, M. Pignatelli, Expression patterns of the Manabe, K. Enomoto, Reduced expression and aberrant localization of novel catenin p120cas in gastrointestinal cancers, Anticancer Res. 19 p120catenin in human squamous cell carcinoma of the skin, J. Dermatol. (1999) 4401–4405. Sci. 34 (2004) 99–108. [131] G. Moreno-Bueno, D. Hardisson, D. Sarrio, C. Sanchez, R. Cassia, J. [140] H. Sato, T. Hasegawa, Y. Kanai, Y. Tsutsumi, Y. Osamura, Y. Abe, H. Prat, J.G. Herman, M. Esteller, X. Matias-Guiu, L. Palacios, Abnormal- Sakai, S. Hirohashi, Expression of cadherins and their undercoat proteins ities of E- and P-cadherin and catenin (Beta-, gamma-catenin, and p120 (Alpha-, beta-, and gamma-catenins and p120) and accumulation of beta- (Ctn)) expression in endometrial cancer and endometrial atypical catenin with no gene mutations in synovial sarcoma, Virchows Arch.- Int. hyperplasia, J. Pathol. 199 (2003) 471–478. J. Pathol. 438 (2001) 23–30.