ANTICANCER RESEARCH 27: 55-62 (2007)

Review The Biological Relevance of FHL2 in Tumour Cells and its Role as a Putative Cancer Target

KAI KLEIBER, KLAUS STREBHARDT and BERND T. MARTIN

Department of Gynecology and Obstetrics, Medical School, J.W. Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt, Germany

Abstract. The LIM-only FHL2 (four-and-a-half LIM- likely to contribute to human and are of clinical domain protein 2) belongs to the FHL protein family of importance in various forms of cancer. transcriptional cofactors present in various cell lines. FHL2 interacts with a variety of transcription factors known to be Cancer is one of the leading causes of death in developed involved in tumour development. Furthermore, FHL2 expression countries and is presently responsible for about 25% of all is often deregulated in cancer including overexpression and deaths. Every year 0.5% of the population are diagnosed with down-regulation in various types of tumours. The function of cancer (16). It affects people of all ages, but the risk increases FHL2 in cancer is particularly intriguing, since it may act as an dramatically at the age of 60. The most common cancer in oncoprotein or as a tumour suppressor in a tissue-dependent adult males is prostate cancer and breast cancer in adult fashion. This dual nature of FHL2 is also reflected by the females. The leading lethal type of cancer in both men and finding that it can function as repressor or activator of women in the US is lung cancer (16). Cancer in young transcriptional activity depending on the cell-type. The ability of children and adolescents is rare, but can occur. Leukaemia is FHL2 to exert functional diversity lies within its structural one of the most common cancers in this group (13). Another composition as a LIM-only protein. LIM-domains are type of cancer, rhabdomyosarcoma, arises from muscle tissue enzymatically inactive protein-to-protein interaction domains, and is exclusively found in children (37). The development of which determine the function of LIM-only as adaptor cancer can have different causes. Some cancers could be molecules or scaffolding proteins. By selectively using different congenital, such as breast cancer, and others are associated LIM-domains for protein-to-protein interactions, FHL2 is with viral infections, such as cervical cancer which correlates capable to interact with a broad spectrum of functionally to the infection with papilloma-virus (42). Ultimately most unrelated proteins, thereby triggering different signalling cancers develop due to the accumulation of DNA mutations pathways. In this review, the current knowledge of FHL2 over the years that negatively affect expression of tumour expression in different cancers was summarized and the suppressor proteins or positively affect the expression of interaction of FHL2 with transcription factors and other proteins oncoproteins. Since there is no single cause for the involved in cancer development was examined. Since development of a specific type of cancer, no cancers are alike. transcription factors control all fundamental developmental and The FHL-subfamily belongs to the LIM-only protein homeostatic processes, transcriptional cofactors like FHL2 are family and consists of four LIM-domains and a single motif at the amino-terminus. Five members have been described so far, FHL1-4 and ACT (activator of CREM in testis) (6, 27, 28, 43). One intact LIM-domain Abbreviations: FHL2, four-and-a-half LIM-domain protein 2; aa, consists of a double zinc finger structure which mediates amino acids; bp, base pairs. protein-to-protein interactions (19, 26). FHL1, FHL2 and FHL3 are mainly expressed in muscle (28, 38), whereas Correspondence to: Dr. Bernd Thomas Martin, Department of FHL1 and FHL2 can also be found in tissues of different Gynecology and Obstetrics, Medical School, J.W. Goethe- origin (28, 39, 43). The expression of FHL4 and ACT is University, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany. Tel: restricted to testis (27). While FHL proteins can fulfill many +49 69 63016894, Fax: +49 69 63016364, e-mail: [email protected] different functions depending on the cell-type and the interacting protein, the modulation of Key Words: FHL2, expression level, transcriptional cofactor, review. activity seems to be a common feature for all FHL-proteins.

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Structure and Function of FHL2 cells increased myotube formation and, thus, the differentiation of these cells (25). FHL2-expression is also FHL2 is the best studied member of the FHL-family. It was down-regulated in prostate cancer (17). In contrast, originally identified by subtractive cloning of normal overexpression of FHL2 could be detected in ovarian cancer myoblasts and rhabdomyosarcoma cells (14). This early study (12), human melanoma (5), lung cancer (43), colon carcinoma demonstrated that the protein is down-regulated in all (4) or breast cancer (12) compared to normal tissues. rhabdomyosarcoma tested compared to healthy muscle tissues. This finding led to its original name DRAL (down- FHL2 in breast cancer. The first indication that FHL2 could regulated in rhabdomyosarcoma LIM-protein). FHL2 is a play a role in breast cancer development came from a study protein of 279 amino acids (aa) in length containing four full by Yan et al. showing that FHL2 was expressed in ovarian LIM-domains and a half LIM-domain at the amino-terminus and breast cancer and was able to interact with the breast (Figure 1). The FHL2 mRNA encompasses 1416 bp. The cancer susceptibility BRCA1 via the carboxy-terminal corresponding gene was mapped to 2q12-q13 domain of BRCA1 (50). by FISH (fluorescent in situ hybridisation) analysis. It Our recent studies revealed that FHL2 was not expressed consists of seven exons, of which only the last four code for in normal breast tissue, but malignant tumours showed high the FHL2-polypeptide (4). Due to the differential usage of expression levels. Interestingly, in the non-malignant “Ductal different LIM-domains, FHL2 is able to interact with many Carcinoma In Situ” (DCIS), lower levels of FHL2-expression different proteins, i.e., depending on the interaction partner compared to malignant tumours could be detected, also different LIM-domains are involved. The association with suggesting a role of FHL2 in the development of breast FHL2 can be mediated by the full-length protein as cancer (unpublished data). A typical immunohistochemical described for the interaction with ‚-catenin (25, 45), by LIM staining of FHL2 in breast cancer and normal breast tissue is domains ½-2 for FOXO1 (51), by LIM-domains ½-3 for shown in Figure 2. Further clinicopathological studies CDC47 (4), by the C-terminal LIM-domains LIM 2-4 for demonstrated that FHL2 was overexpressed in breast cancer BRCA1 (50) or by the C-terminal LIM-domains 3-4 for compared to normal breast tissue (11). Furthermore, the NP220 (31). While GAL4-dependent reporter gene assays survival rate of breast cancer patients correlated with the indicate that the different LIM-domains can have different level of FHL2-expression. The effect of anticancer treatment regulatory effects on their interacting partners, the mode of on FHL2 expression was also analysed, i.e. treatment with action requires further elucidation (50). tamoxifen, an antihormone of (‚)17-estrogen, partly reversed To date, only very little is known about the regulation of the negative prognostic impact of high FHL2-expression FHL2-expression. Still, there are data indicating that the (11). Interestingly, FHL2 is also able to interact with the tumour suppressor protein induces transcription of FHL2 estrogen (18). Still, the functional consequences of (39). While high levels of FHL2-mRNA were found in this interaction remain to be elucidated. primary myoblasts expressing wild-type p53, only low levels of FHL2-mRNA were detectable in rhabdomyosarcoma FHL2 in ovarian cancer. Ovarian cancer is an idiopathic cancer. exhibiting a mutated form of p53. Scholl et al. demonstrated The detailed mechanisms underlying its development are still that the transient transfection of wild-type p53 in unknown; however, a few studies have suggested a hereditary rhabdomyosarcoma cells reinstated FHL2-expression (39). disposition. There are also data showing that mutations of FHL2 was found to play a role in the regulation of signal BRCA1 and BRCA2 lead to a higher risk of developing transduction, and cytoskeleton modulation, ovarian cancer and breast cancer (21). FHL2 is overexpressed as well as in cell adhesion, survival and mobility (5, 22, 25, in epithelial ovarian cancer compared to normal ovarian tissue 29, 48). Consistently, FHL2 can be localised in the nucleus, (12). Gabriel et al. analysed the localisation of the FHL2 the cytoplasm in association with the cytoskeleton. FHL2 protein in human ovarian cancer cells by immunohistochemical promotes differentiation of muscle precursor cells and acts techniques and found that it was mainly localised at the as a scaffolding protein in mature heart (22, 25). membrane and in the cytoplasm, indicating a role in initial events of signal transduction. In line with this observation, FHL2-expression in Cancer FHL2 interacts with pp125FAK (focal adhesion kinase), a non- receptor tyrosine kinase that is expressed throughout Significant differences in the level of FHL2-expression development and in adult tissues (12). pp125FAK is not only comparing normal and cancer tissues could be observed in involved in integrin-mediated signal transduction, it is also many organs (Table I). FHL2 was found to be down-regulated regulated via growth receptors, G-protein receptors and in rhabdomyosarcoma compared to normal myoblasts neuropeptides, such as endothelin and bombesin (52). indicating a role as a tumour suppressor gene in muscle tissue. Whether the interaction of FHL2 with FAK contributes to Concomitantly, overexpression of FHL2 in muscle precursor cancer development is still an unanswered question.

56 Kleiber et al: The Function of FHL2 in Cancer (Review)

Figure 1. Structure of the LIM-only protein FHL2. FHL2 is a 279 amino acid protein consisting of four LIM domains and a half LIM domain at the N-terminus of the protein.

Figure 2. Expression pattern of FHL2 in primary breast cancer tissue. A) 100-fold (left panel) and 400-fold (right panel) magnification of normal breast tissue. B) 100-fold (left panel) and 400-fold (right panel) magnification of cancer tissue. Arrow indicate nuclear, arrow-heads indicate cytosolic FHL2 staining.

FHL2 in prostate cancer. The (AR) plays Table I. Expression profile of FHL2 in cancer and normal tissue. an important role in prostate cancer progression. Different Tissue Normal tissue Cancer studies suggest that the expression pattern of the androgen receptor characterises different stages of cancer progression: Breast – + Colon – + while in advanced cancer, higher levels of AR compared to Lung – + normal tissue is expressed, in localised prostate cancer only Muscle + – a low frequency can be detected (41). Recently it was Ovary – + demonstrated that co-regulators of AR were overexpressed Prostate + – in advanced prostate cancers (8). FHL2 was able to interact Skin ? +

57 ANTICANCER RESEARCH 27: 55-62 (2007) with the AR in prostate cancer cell lines and acted as a Table II. Interaction partners of FHL2 involved in carcinogenesis. coactivator of AR-dependent gene expression (30). To elucidate the role of AR transcription in more detail, Interaction partner Function Reference Kinoshita et al. tested the mRNA expression of different Androgen receptor Co-activator Müller et al. 2000 (30) AR cofactors in primary prostate cancers in comparison to AP-1 Co-activator Morlon and normal tissues by real-time PCR (17). These experiments Sassone-Corsi 2003 (29) revealed that the expression of FHL2 was decreased 2- to BRCA1 unknown Yan et al. 2003 (50) 4-fold in prostate cancer relative to normal tissue (17). CBP/p300 Co-activator Labalette et al. 2004 (20) CDC47 unknown Chan et al. 2000 (4) Co-repressor Paul et al. 2006 (55) The Interaction of FHL2 with Proteins Involved in ERK2 Co-repressor Purcell et al. 2004 (34) Carcinogenesis Oestrogen receptor alpha unknown Kobayashi et al. 2004 (18) FOXO1 Co-repressor Yang et al. 2005 (51) The aberrant expression of FHL2 in certain tumours led to HIPK2 Co-activator Lee et al. 2006 (23) Pp125FAK Unknown Gabriel et al. 2004 (12) the question whether FHL2 can act as an oncoprotein or a SKI Co-activator Chen et al. 2003 (5) tumour suppressor in a cell type-specific manner. Most ‚1-integrin unknown Wixler et al. 2000 (48) likely, the functional duality of FHL2 in different cancer ‚-catenin Co-repressor Martin et al. 2002 (25) cells correlates to its potential to act as a transcriptional Co-activator Wei et al. 2003 (45) cofactor. It is known that FHL2 can play a dual role as transcriptional activator or repressor depending on the cell- type in which it is expressed. In muscle cells, FHL2 was identified as an interaction partner of ‚-catenin and FHL2 transcription. Recently it was demonstrated that the AR was able to repress ‚-catenin-dependent transcription in a was also able to mediate MAPK-related signalling. The dose-dependent manner (25). On the other hand, FHL2 was non-hydrolysable androgen agonist R1881 activated ERK identified in hepatoblastoma cells as an activator of ‚- (extracellular signal-related protein kinase) in human catenin-dependent transcription (45). Since FHL2 acts breast cancer cells (54) and dihydrotestosterone increased mainly as an adaptor protein, it can be postulated that ERK phosphorylation in primary prostate stroma cells (33). FHL2 has the capability to modulate gene expression by Since FHL2 was able to interact directly with the AR, as triggering different transcription factors. In fact, many well as with various partners of the MAPK pathway, such transcription factors interacting with FHL2 are either as ERK2 and c-jun (29, 34), it could be concluded that repressed or activated by FHL2 (Table II). FHL2 might play a role in this pathway. In addition, FHL2 regulates AR-related transcription directly on the DNA FHL2 and CDC47 in cell cycle regulation. One of the first level. FHL2 was able to stimulate AR-dependent activity studies that revealed FHL2 as a regulator of the cell cycle on a naturally occurring indicating another role have demonstrated that FHL2 was able to interact with of FHL2 in prostate cancer progression (30). CDC47 in the nucleus (4). CDC47 is a member of the MCM In addition, FHL2 interacts with the family (minichromosome maintenance), which plays a role (ER), which is usually located in the cytoplasm, but can also in early stages of chromosomal DNA replication. CDC47 be found at the membrane or in the nucleus. The ER is also enters the nucleus during mitosis, where it remains until the activated by binding to hormone followed by the formation initiation of DNA replication and is exported back into the of homodimers, which directly bind to oestrogen response cytoplasm at the beginning of S-phase (47). As long as elements (EREs) on DNA, thereby inducing ER-related CDC47 localises to the nucleus, it interacts with FHL2 in transcription. The ER is divided in mainly two subfamilies, colorectal adenocarcinoma SW480 and HeLa S3 cells (4). the oestrogen receptor alpha (ER·) and the oestrogen Still, how FHL2 influences the mitotic properties of CDC47 receptor beta (ER‚). The ER· can be found in breast will be subject of future research. cancer cells, ovarian stroma cells, endometrium and the hypothalamus (49), whereas the ER‚ is expressed in kidney, FHL2 and the regulation of steroid hormone-dependent brain, bone, heart, prostate and various other tissues (1). pathways. FHL2 seems also involved in steroid hormone- Kobayashi et al. revealed that FHL2 interacts with the ER· related pathways. FHL2 is able to interact with the AR in in the presence of ‚17-oestradiol, but not in the presence of the nucleus of prostate cancer cells (30). Androgen plays the anti-estrogens tamoxifen or raloxifen. However, FHL2 an important role in cell-cycle progression. The functional did not effect ER·-dependent transcription in reporter gene modulation of the AR is achieved by androgen binding analysis on an ERE-dependent reporter. Thus, the effect of leading to the dimerisation, activation and nuclear the interaction of FHL2 and the ER still remains unclear. translocation of the receptor where it regulates gene It is known that oestrogen was able to induce BRCA1

58 Kleiber et al: The Function of FHL2 in Cancer (Review) mRNA-expression by recruiting an AP1/ER· complex to proteins found inside of nuclei. The main components the proximal BRCA1 promoter (15). Since FHL2 can involved in chromatin packaging are histones, which act as interact with AP1, ER· and BRCA1 (18, 29, 50), it might spools around which 148-165 bp of DNA winds. By this, the play a regulative role in this context. DNA is compacted and 50,000 times shorter than an unpacked molecule. To date, five major histone classes are FHL2 and SKI in human melanoma. The oncoprotein SKI known in eukaryotes, H1 (also known as the linker histone (Sloan-Kettering viral oncogene homologue), which or H5), H2A, H2B, H3 and H4. H2A, H2B, H3 and H4 are contributes to the progression of melanoma (36), cervical called core histones, which form an octameric nucleosome carcinoma (9) and oesophageal squamous cell carcinoma core particle. (10), was also found to interact with FHL2, leading to an Weintraub and Groudine postulated that because the enhancement of the FHL2-mediated activation of DNA is condensed as chromatin and not accessible to ‚-catenin-dependent transcription (5). SKI was originally enzymes, gene expression must involve selective disruption identified as an inhibitor of TGF‚ (tranforming-growth of the folded structure (46), so posttranslational factor ‚) in the nucleus by associating with Smad proteins. modifications of nucleosomal histones must occur. However, recent studies have indicated that SKI might play Nowadays, three methods of chromatin remodelling are a role in cancer progression. Whereas in normal known: induction by specialised complexes under the use melanocytes and non-invasive melanoma SKI localises of ATP (2), replacement of one or more core histones (35, exclusively in the nucleus, it was also found in the cytoplasm 40) and covalent modifications of histones (53). Of all of primary invasive melanoma. FHL2 might have an modifications known, acetylation and deacetylation of the apoptotic function in several cell lines including melanoma amino-terminal tail of nucleosomal histones are the most (5). SKI seems to be able to block FHL2-mediated widely investigated. Acetylation and deacetylation are apoptosis by turning FHL2 into a growth stimulator for mediated by histone acetyltransferases (HAT) and histone mouse melanocytes and human melanoma cells (5). deacetylases (HDAC). FHL2 is not only known to interact with histone deacetylases like Sirtuin-1 (SIRT1) and FHL2 and p53. p53 is activated by DNA damage and histone acetyltransferase such as CBP/p300 (20, 51), but arrests the cell cycle by inducing p21Waf1, which leads to also with other regulative factors of acetylation and inhibition of the cyclin D/CDK4/6 complex, thereby deacetylation, such as the Forkhead class box proteins O giving the cell enough time for necessary repairs. p53 (FOXO) transcription factors (51). FOXO functions regulates the expression of FHL2 (39). Recently it was downstream of the PTEN tumour suppressor and directly also shown that FHL2 was able to regulate p53- control the expression of involved in apoptosis, cell dependent transcription through a direct association with cycle progression and stress response. FHL2 was identified HIPK2 (23). HIPK2 has been described as a as an interaction partner of FOXO1 in the nucleus of homeodomain-interacting protein kinase involved in prostate cancer cells where FHL2 decreases the TNF-R1 (tumour necrosis factor receptor type 1)- transcriptional activity of FOXO1. This repression is mediated signalling (24) and therefore plays a role in mediated by the HDAC SIRT1 which is able to deacetylate tumour development. HIPK2 can bind, stabilise and FOXO1 and inhibits its transcriptional activity. FHL2 phosphorylate p53, inducing p53 transcriptional activity enhances this interaction and thereby the deacetylation of and apoptotic function (7, 44). Recently a study by Lee et FOXO1. This, in turn, leads to repression of FOXO1- al. revealed that FHL2, p53 and HIPK2 not only form a dependent transcription and abolishes the repression of ternary complex but are also associated with the p21Waf1 FOXO1 on Cyclin D1, indicating that FHL2 is not a classic promoter. Reporter gene analyses have indicated that co-repressor, but functions as an adapter of FOXO1 and HIPK2 enhances the p53-dependent transcriptional SIRT1 (51). activation and that FHL2 is able to increase this process FHL2 was shown to interact with the CBP/p300 (23). Taken together, these data provide additional acetyltransferase which individually stimulates ‚-catenin evidence for the involvement of FHL2 in cell cycle transcriptional activity. CBP/p300 was the first acetyl- regulation and cancer development. transferase identified. It acetylates all four core histones and acts as a transcriptional adaptor (32). FHL2, CBP/p300 and The Role of FHL2 in the Acetylation and ‚-catenin from a ternary complex in the nucleus, which leads Deacetylation of Proteins to enhanced ‚-catenin/TCF-mediated and AR-mediated transcription. Since a number of transcription factors are The regulation of gene expression is not restricted to the known to be acetylated by p300/CBP (3), it can be assumed activity of transcription factors. It can also be modulated on that FHL2 exerts its function as transcriptional cofactor, at the chromatin level. Chromatin is a complex of DNA and least in part, by modulating the activity of HATs and HDACs.

59 ANTICANCER RESEARCH 27: 55-62 (2007)

Conclusion 9 Fujimoto T, Nishikawa A, Iwasaki M, Akutagawa N, Teramoto M and Kudo R: Gene expression profiling in two morpholo- The data summarised in this review strongly indicate an gically different uterine cervical carcinoma cell lines derived involvement of the transcriptional cofactor FHL2 in the from a single donor using a human cancer cDNA array. Gynecol Oncol 93: 446-453, 2004. progression or suppression of cancer growth. Nevertheless, 10 Fukuchi M, Nakajima M, Fukai Y, Miyazaki T, Masuda N, Sohda data showing a direct contribution of FHL2 to cancer growth M, Manda R, Tsukada K, Kato H and Kuwano H: Increased in the literature are still missing, indicating the need for expression of c-Ski as a corepressor in transforming growth factor- further studies to evaluate this aspect in more detail. For beta signaling correlates with progression of esophageal squamous instance, a stable knock-down of FHL2 in cancer cells by using cell carcinoma. Int J Cancer 108: 818-824, 2004. siRNA-based techniques would help to study the contribution 11 Gabriel B, Fischer DC, Orlowska-Volk M, zur HA, Schule R, of FHL2 to important malignant features of tumour cells, such Muller JM and Hasenburg A: Expression of the transcriptional coregulator FHL2 in human breast cancer: a clinicopathologic as contact inhibition, the ability to form colonies in soft agar study. J Soc Gynecol Investig 13: 69-75, 2006. or anchorage-independent growth. Furthermore, FHL2- 12 Gabriel B, Mildenberger S, Weisser CW, Metzger E, Gitsch G, depleted cancer cells could be used for Xenograft experiments Schule R and Muller JM: Focal adhesion kinase interacts with in nude mice to analyse the impact of FHL2 on cancer growth the transcriptional coactivator FHL2 and both are overexpressed and invasion in vivo. If future experiments would identify in epithelial ovarian cancer. Anticancer Res 24: 921- 927, 2004. FHL2 as a cell-specific oncogene or tumour-suppressor, FHL2 13 Gaynon PS: Childhood acute lymphoblastic leukaemia and could become an attractive target for therapeutical relapse. Br J Haematol 131: 579-587, 2005. interventions. Understanding the mechanisms behind the 14 Genini M, Schwalbe P, Scholl FA, Remppis A, Mattei MG, and Schafer BW: Subtractive cloning and characterization of potential dual function of FHL2 as tumour suppressor or DRAL, a novel LIM-domain protein down-regulated in oncoprotein will especially help to understand how rhabdomyosarcoma. DNA Cell Biol 16: 433-442, 1997. transcriptional cofactors, the most distal elements of signalling 15 Hockings JK, Thorne PA, Kemp MQ, Morgan SS, Selmin O, pathways, contribute to human carcinogenesis. and Romagnolo DF: The ligand status of the aromatic hydrocarbon receptor modulates transcriptional activation of Acknowledgements BRCA-1 promoter by estrogen. Cancer Res 66: 2224-2232, 2006. 16 Jemal A, Murray T, Ward E, Samuels A, Tiwari RC, Ghafoor K. Kleiber was supported by a grant of the Sander Foundation. A, Feuer EJ, and Thun MJ: Cancer statistics, 2005. CA Cancer J Clin 55: 10-30, 2005. References 17 Kinoshita M, Nakagawa T, Shimizu A and Katsuoka Y: Differently regulated androgen receptor transcriptional 1 Babiker FA, De Windt LJ, van Eickels M, Grohe C, Meyer R complex in prostate cancer compared with normal prostate. Int and Doevendans PA: Estrogenic hormone action in the heart: J Urol 12: 390-397, 2005. regulatory network and function. Cardiovasc Res 53: 709-719, 18 Kobayashi S, Shibata H, Yokota K, Suda N, Murai A, Kurihara 2002. I, Saito I, and Saruta T: FHL2, UBC9, and PIAS1 are novel 2 Becker PB and Horz W: ATP-dependent nucleosome -interacting proteins. Endocr Res 30: remodeling. Annu Rev Biochem 71: 247-273, 2002. 617-621, 2004. 3 Chan HM and La Thangue NB: p300/CBP proteins: HATs for 19 Kosa JL, Michelsen JW, Louis HA, Olsen JI, Davis DR, transcriptional bridges and scaffolds. J Cell Sci 114: 2363-2373, Beckerle MC and Winge DR: Common metal ion coordination 2001. in LIM domain proteins. Biochemistry 33: 468-477, 1994. 4 Chan KK, Tsui SK, Ngai SM, Lee SM, Kotaka M, Waye MM, 20 Labalette C, Renard CA, Neuveut C, Buendia MA and Wei Y: Lee CY and Fung KP: Protein-to-protein interaction of FHL2, Interaction and functional cooperation between the LIM a LIM domain protein preferentially expressed in human heart, protein FHL2, CBP/p300, and betacatenin. Mol Cell Biol 24: with hCDC47. J Cell Biochem 76: 499-508, 2000. 10689-10702, 2004. 5 Chen D, Xu W, Bales E, Colmenares C, Conacci-Sorrell M, 21 Lancaster JM, Carney ME and Futreal PA: BRCA 1 and 2 – a Ishii S, Stavnezer E, Campisi J, Fisher DE, Ben Ze'ev A and Genetic Link to Familial Breast and Ovarian Cancer. Medscape Medrano EE: SKI activates Wnt/betacatenin signaling in human Womens Health 2: 7, 1997. melanoma. Cancer Res 63: 6626-6634, 2003. 22 Lange S, Auerbach D, McLoughlin P, Perriard E, Schafer BW, 6 Chu PH, Ruiz-Lozano P, Zhou Q, Cai C and Chen J: Perriard JC and Ehler E: Subcellular targeting of metabolic Expression patterns of FHL/SLIM family members suggest enzymes to in heart muscle may be mediated by important functional roles in skeletal muscle and cardiovascular DRAL/FHL-2. J Cell Sci 115: 4925-4936, 2002. system. Mech Dev 95: 259-265, 2000. 23 Lee SW, Kim EJ and Um SJ: FHL2 mediates p53-induced 7 Di S, V, Blandino G, Sacchi A, Soddu S and D'Orazi G: HIPK2 transcriptional activation through a direct association with neutralizes MDM2 inhibition rescuing p53 transcriptional HIPK2. Biochem Biophys Res Commun 339: 1056-1062, 2006. activity and apoptotic function. Oncogene 23: 5185-5192, 2004. 24 Li X, Wang Y, Debatin KM and Hug H: The serine/threonine 8 Fujimoto N, Mizokami A, Harada S and Matsumoto T: kinase HIPK2 interacts with TRADD, but not with CD95 or Different expression of androgen receptor coactivators in TNF-R1 in 293T cells. Biochem Biophys Res Commun 277: human prostate. Urology 58: 289-294, 2001. 513-517, 2000.

60 Kleiber et al: The Function of FHL2 in Cancer (Review)

25 Martin B, Schneider R, Janetzky S, Waibler Z, Pandur P, Kuhl 41 Suzuki H, Ueda T, Ichikawa T and Ito H: Androgen receptor M, Behrens J, von der MK, Starzinski-Powitz A and Wixler V: involvement in the progression of prostate cancer. Endocr Relat The LIM-only protein FHL2 interacts with beta-catenin and Cancer 10: 209-216, 2003. promotes differentiation of mouse myoblasts. J Cell Biol 159: 42 Syrjanen KJ: Condylomatous lesions in dysplastic and neoplastic 113-122, 2002. epithelium of the uterine cervix. Surg Gynecol Obstet 150: 372- 26 Michelsen JW, Schmeichel KL, Beckerle MC and Winge DR: 376, 1980. The LIM motif defines a specific zinc-binding protein domain. 43 Tanahashi H and Tabira T: Alzheimer's disease-associated Proc Natl Acad Sci USA 90: 4404-4408, 1993. presenilin 2 interacts with DRAL, an LIM-domain protein. 27 Morgan MJ and Madgwick AJ: The fourth member of the FHL Hum Mol Genet 9: 2281-2289, 2000. family of LIM proteins is expressed exclusively in the testis. 44 Wang Y, Debatin KM and Hug H: HIPK2 overexpression leads Biochem Biophys Res Commun 255: 251-255, 1999. to stabilization of p53 protein and increased p53 transcriptional 28 Morgan MJ and Madgwick AJ: The LIM proteins FHL1 and activity by decreasing Mdm2 protein levels. BMC Mol Biol 2: FHL3 are expressed differently in skeletal muscle. Biochem 8, 2001. Biophys Res Commun 255: 245-250, 1999. 45 Wei Y, Renard CA, Labalette C, Wu Y, Levy L, Neuveut C, 29 Morlon A and Sassone-Corsi P: The LIM-only protein FHL2 is Prieur X, Flajolet M, Prigent S and Buendia MA: Identification a serum-inducible transcriptional coactivator of AP-1. Proc Natl of the LIM protein FHL2 as a coactivator of beta-catenin. J Acad Sci USA 100: 3977-3982, 2003. Biol Chem 278: 5188-5194, 2003. 30 Müller JM, Isele U, Metzger E, Rempel A, Moser M, Pscherer 46 Weintraub H and Groudine M: Chromosomal subunits in active A, Breyer T, Holubarsch C, Buettner R and Schule R: FHL2, a genes have an altered conformation. Science 193: 848-856, 1976. novel tissue-specific coactivator of the androgen receptor. 47 Whitebread LA and Dalton S: Cdc54 belongs to the EMBO J 19: 359-369, 2000. Cdc46/Mcm3 family of proteins which are essential for initiation 31 Ng EK, Chan KK, Wong CH, Tsui SK, Ngai SM, Lee SM, of eukaryotic DNA replication. Gene 155: 113-117, 1995. Kotaka M, Lee CY, Waye MM and Fung KP: Interaction of 48 Wixler V, Geerts D, Laplantine E, Westhoff D, Smyth N, the heart-specific LIM domain protein, FHL2, with DNA- Aumailley M, Sonnenberg A and Paulsson M: The LIM-only binding nuclear protein, hNP220. J Cell Biochem 84: 556-566, protein DRAL/FHL2 binds to the cytoplasmic domain of 2002. several alpha and beta integrin chains and is recruited to 32 Ogryzko VV, Schiltz RL, Russanova V, Howard BH and adhesion complexes. J Biol Chem 275: 33669-33678, 2000. Nakatani Y: The transcriptional coactivators p300 and CBP are 49 Yaghmaie F, Saeed O, Garan SA, Freitag W, Timiras PS and histone acetyltransferases. Cell 87: 953-959, 1996. Sternberg H: Caloric restriction reduces cell loss and maintains 33 Peterziel H, Mink S, Schonert A, Becker M, Klocker H and estrogen receptor-alpha immunoreactivity in the pre-optic Cato AC: Rapid signalling by androgen receptor in prostate hypothalamus of female B6D2F1 mice. Neuro Endocrinol Lett cancer cells. Oncogene 18: 6322-6329, 1999. 26: 197-203, 2005. 34 Purcell NH, Darwis D, Bueno OF, Muller JM, Schule R and 50 Yan J, Zhu J, Zhong H, Lu Q, Huang C and Ye Q: BRCA1 Molkentin JD: Extracellular signal-regulated kinase 2 interacts interacts with FHL2 and enhances FHL2 transactivation with and is negatively regulated by the LIM-only protein FHL2 function. FEBS Lett 553: 183-189, 2003. in cardiomyocytes. Mol Cell Biol 24: 1081-1095, 2004. 51 Yang Y, Hou H, Haller EM, Nicosia SV and Bai W: 35 Redon C, Pilch D, Rogakou E, Sedelnikova O, Newrock K and Suppression of FOXO1 activity by FHL2 through SIRT1- Bonner W: Histone H2A variants H2AX and H2AZ. Curr Opin mediated deacetylation. EMBO J 24: 1021-1032, 2005. Genet Dev 12: 162-169, 2002. 52 Zachary I and Rozengurt E: Focal adhesion kinase (p125FAK): 36 Reed JA, Bales E, Xu W, Okan NA, Bandyopadhyay D and a point of convergence in the action of neuropeptides, integrins, Medrano EE: Cytoplasmic localization of the oncogenic protein and oncogenes. Cell 71: 891-894, 1992. Ski in human cutaneous melanomas in vivo: functional 53 Zhang Y and Reinberg D: Transcription regulation by histone implications for transforming growth factor beta signaling. methylation: interplay between different covalent modifications Cancer Res 61: 8074-8078, 2001. of the core histone tails. Genes Dev 15: 2343-2360, 2001. 37 Rodeberg D and Paidas C: Childhood rhabdomyosarcoma. 54 Zhu X, Li H, Liu JP and Funder JW: Androgen stimulates Semin Pediatr Surg 15: 57-62, 2006. mitogen-activated protein kinase in human breast cancer cells. 38 Samson T, Smyth N, Janetzky S, Wendler O, Muller JM, Schule Mol Cell Endocrinol 152: 199-206, 1999. R, von der MH, von der MK and Wixler V: The LIM-only 55 Paul C, Lacroix M, Iankova I, Julien E, Schafer BW, Labalette proteins FHL2 and FHL3 interact with alpha- and beta-subunits C, Wei Y, Cam AL, Cam LL and Sardet C: The LIM-only of the muscle alpha7beta1 integrin receptor. J Biol Chem 279: protein FHL2 is a negative regulator of E4F1. Oncogene, in 28641-28652, 2004. press, 2006. 39 Scholl FA, McLoughlin P, Ehler E, de Giovanni C and Schafer BW: DRAL is a p53- responsive gene whose four and a half LIM domain protein product induces apoptosis. J Cell Biol 151: 495-506, 2000. 40 Smith MM: Histone variants and nucleosome deposition Received October 3, 2006 pathways. Mol Cell 9: 1158-1160, 2002. Accepted November 10, 2006

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