DOCSLIB.ORG

Expression and Functional Significance of CDC25B in Human Pancreatic

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Expression and Functional Significance of CDC25B in Human Pancreatic Oncogene (2004) 23, 71–81 & 2004 Nature Publishing Group All rights reserved 0950-9232/04 $25.00 www.nature.com/onc Expression and functional significance of CDC25B in human pancreatic ductal adenocarcinoma Junchao Guo1,2,Jo¨ rg Kleeff1, Junsheng Li1, Jiayi Ding3,Ju¨ rgen Hammer3, Yupei Zhao2, Thomas Giese4, Murray Korc5, Markus W Bu¨ chler1 and Helmut Friess*,1 1Department of General Surgery, University of Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany; 2Department of General Surgery, Peking Union Medical College Hospital, Beijing, China; 3Roche Genomic and Information Sciences, Hoffmann-La Roche Inc., Nutley, NJ, USA; 4Institute of Immunology, University of Heidelberg, Heidelberg, Germany; 5Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Biological Chemistry and Pharmacology, University of California, Irvine, CA, USA Pancreatic ductal adenocarcinoma (PDAC) is one of the pancreatic cancer cases in the US was 30 300, while the leading causes of cancer-related deaths. Deregulation of estimated number of deaths was 29 700 (Jemal et al., cell-cycle control is thought to be a crucial event in 2002). PDAC is characterized by late diagnosis, early malignant transformation, and CDC25 phosphatases are recurrence after potential curative resection, and relative a familyof cyclin-dependent kinase activators, which act unresponsiveness to standard oncological therapies such at different points of the cell cycle, including G1–S and as radiotherapy and chemotherapy (DiMagno et al., G2–M transition. Here, we investigated the expression 1999). The overall 5-year survival rate is less than 5%, and functional significance of CDC25s in PDAC. and more than 85% of the tumors are diagnosed when CDC25B mRNA expression levels in human pancreatic the tumor has infiltrated into adjacent organs or when tissue samples were analysed by cDNA array, quantitative distant metastases are present (Gudjonsson, 1987). PCR and Northern blotting. Immunohistochemistrywas Furthermore, even after potential curative resection, carried out to localize and quantifyCDC25B expression. the 5-year survival rate is only around 20% in large Two specific CDC25B inhibitors were utilized to deter- series (Neoptolemos et al., 2001a, b). Numerous studies mine the functional relevance of CDC25B. Byquantitative have documented different genetic and epigenetic RT–PCR, CDC25B mRNA was overexpressed in pan- alterations in PDAC, including mutations of the proto- creatic cancer (7.5-fold) in comparison to the normal oncogene K-ras, and tumor-suppressor gene mutations pancreas. Strong nuclear CDC25B immunoreactivitywas such as those of p53, Smad4/DPC4 and p16/CDKN2A present in both pancreatic and metastatic cancer samples, (Bardeesy and DePinho, 2002). In addition, overexpres- and there was a marked increase of the percentage of sion of growth factors and growth factor receptors is positive cells in primarycancer (48.6 716.3%) and present in a significant proportion of these tumors, and metastatic tissues (71.773.1%) compared to normal PDACs display a number of different alterations in samples (8.371.8%). Two CDC25B inhibitors reduced apoptosis, invasion and metastasis-regulating pathways. the growth of pancreatic cancer cell lines, resulting in the These changes combine to give PDAC cells a distinct accumulation of phosphorylated CDC2 and G2/M arrest. growth advantage (Kleeff et al., 1998; Koliopanos et al., These findings demonstrate an important role of CDC25B 2001; Liao et al., 2001; Ozawa et al., 2001). in cell-cycle progression, raising the possibility that Deregulation of cell-cycle control is thought to be a inhibition of CDC25B mayhave therapeutic potential in crucial event in the malignant transformation of cells pancreatic cancer. (Tsai and McKay, 2002). Alterations in cell-cycle Oncogene (2004) 23, 71–81. doi:10.1038/sj.onc.1206926 regulatory genes are commonly found in human cancers (Sherr, 1996), and cell proliferation that reflects cell- Keywords: cell cycle, cyclin-dependent kinase, CDC25B, cycle progression is an influential factor contributing to pancreatic ductal adenocarcinoma the aggressive growth behavior of cancer cells. Two critical checkpoints have been characterized, and are located at the G1–S phase and G2–Mphase transitions. Introduction Central components in the cell-cycle machinery are cyclins and their corresponding cyclin-dependent Pancreatic ductal adenocarcinoma (PDAC) is the fourth kinases (CDKs). The complexes of CDK/cyclin are leading cause of cancer-related deaths in the United activated and inactivated sequentially to regulate States according to the latest statistical analysis (Jemal different phases of the cell cycle. Several gene mutations et al., 2002). In 2002, the estimated number of new are involved in deregulated cell-cycle progression in PDAC, such as mutations of the tumor-suppressor gene *Correspondence: H Friess; E-mail: [email protected] p53, which result in antiapoptotic responses and anti- berg.de G1–S phase arrest; mutations of K-ras, which result in Received 16 May 2003; revised 28 June 2003; accepted 1 July 2003 continued cell proliferation and survival (Bardeesy and CDC25B in pancreatic cancer J Guo et al 72 DePinho, 2002); and mutations of CDKN2A, which pancreas, respectively. Furthermore, in metastatic encodes two tumor suppressors – INK4a and ARF – lesions, CDC25B levels were increased 2.2- and 4.1-fold that disrupt retinoblastoma (RB) and p53 pathways, in comparison with primary cancer and normal pan- subsequently resulting in uncontrolled cell-cycle pro- creatic samples, respectively. In contrast, there was no gression (Lal et al., 2000). significant change in CDC25A and CDC25C mRNA CDC25 phosphatases, consisting of CDC25A, B and levels between pancreatic cancer, chronic pancreatitis C, are a novel family of CDK phosphatases, which and normal pancreatic samples. activate CDK/cyclin complexes by dephosphorylation These DNA array results were confirmed by Northern of CDKs at different checkpoints of the cell cycle blot analysis and quantitative RT–PCR. Northern blot (Galaktionov and Beach, 1991; Sebastian et al., 1993). analysis of total RNA isolated from 48 PDAC and 24 CDC25A is expressed in the late G1 phase and controls normal pancreatic tissues revealed absent or weak G1/S transition by activating the CDK2/Cyclin E expression of the approximately 3.0 kb CDC25B mRNA complex (Hoffmann et al., 1994), while CDC25B and transcript (Wu and Wolgemuth, 1995) in the normal C are essential for G2 and G2/Mtransition (Hoffmann samples. In contrast, in 40 of 48 (83%) PDAC samples, et al., 1993; Lammer et al., 1998). CDC25A and the CDC25B mRNA transcript was clearly detectable. CDC25B, but not CDC25C, exhibit oncogenic potential In 26 (54%) of these samples there was strong since they can transform primary murine fibroblasts in expression, whereas in 14 (29%) samples there was low cooperation with either activated H-ras or loss of RB1 to moderate expression of this mRNA moiety in (Galaktionov et al., 1995). Overexpression of CDC25A comparison to normal pancreatic tissues. An example or CDC25B has been reported in different human of a Northern blot depicting eight PDAC and four tumors, including non-Hodgkin’s lymphoma, neuro- normal tissue samples is shown in Figure 1a (upper blastoma, head and neck cancer, lung cancer, esopha- panel). Previously, different splicing variants have been geal cancer, gastric cancer, colorectal cancer and described for CDC25B (Kudo et al., 1997). Therefore, prostate cancer (Gasparotto et al., 1997; Kudo et al., we also characterized splice variants of CDC25B in 1997; Hernandez et al., 2000, 2001; Miyata et al., 2001; cancerous and normal pancreatic tissues by RT–PCR Sasaki et al., 2001; Sato et al., 2001; Ito et al., 2002; using a pair of primers that selectively amplifies four Ngan et al., 2003). The expression and functional role of variants yielding fragments of 627 bp (CDC25B4), CDC25B phosphatases in PDAC has so far not been 522 bp (CDC25B3), 480 bp (CDC25B1) and 399 bp analysed. Therefore, in the present study we investigated (CDC25B2). The CDC25B3 isoform was detectable in the expression of CDC25s in PDAC in order to virtually all cases, but at relatively higher levels in elucidate the role of these genes as modulators of cell- cancerous than in normal tissues. The other isoforms cycle progression in this disease. In addition, CDC25B were below the level of detection (Figure 1a, lower inhibitors were used to study the functional role of these panel). It is currently not known whether these splice phosphatases in the pathogenesis of PDAC. variants are present only at low levels in pancreatic tissues, or alternatively whether there are other less abundant splice variants. Changes in CDC25B mRNA levels were quantified by Results real-time QRT–PCR. In pancreatic cancer samples, the median expression level of CDC25B mRNA was 7.5- CDC25B expression in human pancreatic cancer and 3.9-fold higher than in the normal and chronic We first screened the expression of the three CDC25 pancreatitis tissue samples, respectively (Table 1b). The family members (CDC25A, B and C) in pancreatic expression of the CDC25B3 splicing variant displayed a cancer, chronic pancreatitis and the normal pancreas similar pattern. Thus, CDC25B3 mRNA levels were 6.3- utilizing DNA arrays. This analysis revealed that and 3.2-fold increased in PDAC in comparison with the CDC25B, but not CDC25A or CDC25C, was signifi- normal pancreas and chronic pancreatitis, respectively cantly overexpressed
Load more

Recommended publications
  • CDC25B Mediates Rapamycin-Induced Oncogenic Responses in Cancer Cells
    Published OnlineFirst March 10, 2009; DOI: 10.1158/0008-5472.CAN-08-3222 Research Article CDC25B Mediates Rapamycin-Induced Oncogenic Responses in Cancer Cells Run-qiang Chen,1 Qing-kai Yang,1 Bing-wen Lu,2 Wei Yi,1 Greg Cantin,2 Yan-ling Chen,1 Colleen Fearns,3 John R. Yates III,2 and Jiing-Dwan Lee1 Departments of 1Immunology and Microbial Science, 2Chemical Physiology, and 3Chemistry, The Scripps Research Institute, La Jolla, California Abstract expression of PTEN, increased PI3K activity, and increased expression or activation of AKT in advanced prostate cancer Because the mammalian target of rapamycin (mTOR) pathway (8–10). These aberrations also are indicators of a poor prognosis is commonly deregulated in human cancer, mTOR inhibitors, for prostate cancer patients (11, 12). More importantly, long-term rapamycin and its derivatives, are being actively tested in androgen deprivation treatment for prostate cancer patients that cancer clinical trials. Clinical updates indicate that the reinforces the PI3K/AKT pathway also up-regulates mTOR anticancer effect of these drugs is limited, perhaps due to activation in prostate tumor (9, 10). These abovementioned rapamycin-dependent induction of oncogenic cascades by an experimental and clinical data lead to the supposition that mTOR as yet unclear mechanism. As such, we investigated rapamy- inhibitors (rapamycin and its derivatives) should be effective in cin-dependent phosphoproteomics and discovered that 250 treating human cancer. Unfortunately, recent clinical data indicates phosphosites in 161 cellular proteins were sensitive to that rapamycin shows therapeutic potential in only few types of rapamycin. Among these, rapamycin regulated four kinases human cancer: endometrial carcinoma, renal cell carcinoma, and and four phosphatases.
    [Show full text]
  • Cytokine-Driven Cell Cycling Is Mediated Through Cdc25a
    JCB: ARTICLE Cytokine-driven cell cycling is mediated through Cdc25A Annette R. Khaled,1,3 Dmitry V. Bulavin,2 Christina Kittipatarin,1 Wen Qing Li,3 Michelle Alvarez,1 Kyungjae Kim,3,5 Howard A. Young,4 Albert J. Fornace,2 and Scott K. Durum3 1University of Central Florida, BioMolecular Science Center, Orlando, FL 32628 2Division of Basic Sciences, National Cancer Institute, Bethesda, MD 20892 3Laboratory of Molecular Immunoregulation and 4Laboratory of Experimental Immunology, National Cancer Institute at Frederick, Frederick, MD 21702 5Department of Pharmacy, Sahm-Yook University, Seoul, Korea, 139-742 ymphocytes are the central mediators of the im- the critical mediator of proliferation. Withdrawal of IL-7 mune response, requiring cytokines for survival and or IL-3 from dependent lymphocytes activates the stress L proliferation. Survival signaling targets the Bcl-2 kinase, p38 MAPK, which phosphorylates Cdc25A, in- family of apoptotic mediators, however, the pathway for ducing its degradation. As a result, Cdk/cyclin com- the cytokine-driven proliferation of lymphocytes is poorly plexes remain phosphorylated and inactive and cells understood. Here we show that cytokine-induced cell arrest before the induction of apoptosis. Inhibiting p38 cycle progression is not solely dependent on the synthe- MAPK or expressing a mutant Cdc25A, in which the two sis of cyclin-dependent kinases (Cdks) or cyclins. Rather, p38 MAPK target sites, S75 and S123, are altered, ren- we observe that in lymphocyte cell lines dependent on ders cells resistant to cytokine withdrawal, restoring the interleukin-3 or interleukin-7, or primary lymphocytes activity of Cdk/cyclin complexes and driving the cell cycle dependent on interleukin 7, the phosphatase Cdc25A is independent of a growth stimulus.
    [Show full text]
  • Bioinformatics-Based Screening of Key Genes for Transformation of Liver
    Jiang et al. J Transl Med (2020) 18:40 https://doi.org/10.1186/s12967-020-02229-8 Journal of Translational Medicine RESEARCH Open Access Bioinformatics-based screening of key genes for transformation of liver cirrhosis to hepatocellular carcinoma Chen Hao Jiang1,2, Xin Yuan1,2, Jiang Fen Li1,2, Yu Fang Xie1,2, An Zhi Zhang1,2, Xue Li Wang1,2, Lan Yang1,2, Chun Xia Liu1,2, Wei Hua Liang1,2, Li Juan Pang1,2, Hong Zou1,2, Xiao Bin Cui1,2, Xi Hua Shen1,2, Yan Qi1,2, Jin Fang Jiang1,2, Wen Yi Gu4, Feng Li1,2,3 and Jian Ming Hu1,2* Abstract Background: Hepatocellular carcinoma (HCC) is the most common type of liver tumour, and is closely related to liver cirrhosis. Previous studies have focussed on the pathogenesis of liver cirrhosis developing into HCC, but the molecular mechanism remains unclear. The aims of the present study were to identify key genes related to the transformation of cirrhosis into HCC, and explore the associated molecular mechanisms. Methods: GSE89377, GSE17548, GSE63898 and GSE54236 mRNA microarray datasets from Gene Expression Omni- bus (GEO) were analysed to obtain diferentially expressed genes (DEGs) between HCC and liver cirrhosis tissues, and network analysis of protein–protein interactions (PPIs) was carried out. String and Cytoscape were used to analyse modules and identify hub genes, Kaplan–Meier Plotter and Oncomine databases were used to explore relationships between hub genes and disease occurrence, development and prognosis of HCC, and the molecular mechanism of the main hub gene was probed using Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway analysis.
    [Show full text]
  • The Regulatory Roles of Phosphatases in Cancer
    Oncogene (2014) 33, 939–953 & 2014 Macmillan Publishers Limited All rights reserved 0950-9232/14 www.nature.com/onc REVIEW The regulatory roles of phosphatases in cancer J Stebbing1, LC Lit1, H Zhang, RS Darrington, O Melaiu, B Rudraraju and G Giamas The relevance of potentially reversible post-translational modifications required for controlling cellular processes in cancer is one of the most thriving arenas of cellular and molecular biology. Any alteration in the balanced equilibrium between kinases and phosphatases may result in development and progression of various diseases, including different types of cancer, though phosphatases are relatively under-studied. Loss of phosphatases such as PTEN (phosphatase and tensin homologue deleted on chromosome 10), a known tumour suppressor, across tumour types lends credence to the development of phosphatidylinositol 3--kinase inhibitors alongside the use of phosphatase expression as a biomarker, though phase 3 trial data are lacking. In this review, we give an updated report on phosphatase dysregulation linked to organ-specific malignancies. Oncogene (2014) 33, 939–953; doi:10.1038/onc.2013.80; published online 18 March 2013 Keywords: cancer; phosphatases; solid tumours GASTROINTESTINAL MALIGNANCIES abs in sera were significantly associated with poor survival in Oesophageal cancer advanced ESCC, suggesting that they may have a clinical utility in Loss of PTEN (phosphatase and tensin homologue deleted on ESCC screening and diagnosis.5 chromosome 10) expression in oesophageal cancer is frequent, Cao et al.6 investigated the role of protein tyrosine phosphatase, among other gene alterations characterizing this disease. Zhou non-receptor type 12 (PTPN12) in ESCC and showed that PTPN12 et al.1 found that overexpression of PTEN suppresses growth and protein expression is higher in normal para-cancerous tissues than induces apoptosis in oesophageal cancer cell lines, through in 20 ESCC tissues.
    [Show full text]
  • Supplementary Material
    BMJ Publishing Group Limited (BMJ) disclaims all liability and responsibility arising from any reliance Supplemental material placed on this supplemental material which has been supplied by the author(s) J Neurol Neurosurg Psychiatry Page 1 / 45 SUPPLEMENTARY MATERIAL Appendix A1: Neuropsychological protocol. Appendix A2: Description of the four cases at the transitional stage. Table A1: Clinical status and center proportion in each batch. Table A2: Complete output from EdgeR. Table A3: List of the putative target genes. Table A4: Complete output from DIANA-miRPath v.3. Table A5: Comparison of studies investigating miRNAs from brain samples. Figure A1: Stratified nested cross-validation. Figure A2: Expression heatmap of miRNA signature. Figure A3: Bootstrapped ROC AUC scores. Figure A4: ROC AUC scores with 100 different fold splits. Figure A5: Presymptomatic subjects probability scores. Figure A6: Heatmap of the level of enrichment in KEGG pathways. Kmetzsch V, et al. J Neurol Neurosurg Psychiatry 2021; 92:485–493. doi: 10.1136/jnnp-2020-324647 BMJ Publishing Group Limited (BMJ) disclaims all liability and responsibility arising from any reliance Supplemental material placed on this supplemental material which has been supplied by the author(s) J Neurol Neurosurg Psychiatry Appendix A1. Neuropsychological protocol The PREV-DEMALS cognitive evaluation included standardized neuropsychological tests to investigate all cognitive domains, and in particular frontal lobe functions. The scores were provided previously (Bertrand et al., 2018). Briefly, global cognitive efficiency was evaluated by means of Mini-Mental State Examination (MMSE) and Mattis Dementia Rating Scale (MDRS). Frontal executive functions were assessed with Frontal Assessment Battery (FAB), forward and backward digit spans, Trail Making Test part A and B (TMT-A and TMT-B), Wisconsin Card Sorting Test (WCST), and Symbol-Digit Modalities test.
    [Show full text]
  • Cyclex Protein Phosphatase Cdc25a Fluorometric Assay Kit 100 Assays Cat# CY-1352
    Protein Phosphatase Cdc25A Fluorometric Assay Kit User’s Manual For Research Use Only, Not for use in diagnostic procedures Fluorometric Assay Kit for Measuring Cdc25A Phosphatase Activity CycLex Protein Phosphatase Cdc25A Fluorometric Assay Kit 100 Assays Cat# CY-1352 Intended Use............................................ 1 Storage..................................................... 1 Introduction ............................................. 2 Principle of the Assay.............................. 2 Materials Provided .................................. 3 Materials Required but not Provided.….. 3 Precautions and Recommendations......... 3-4 Detailed Protocol..................................... 4-6 Evaluation of Results .............................. 7-9 Troubleshooting ...................................... 10 Reagent Stability ..................................... 10 References................................................ 11 Related Products.......................................11-12 Intended Use The MBL Research product Protein Phosphatase Cdc25A Fluorometric Assay Kit is a fluorometric and non-radioactive assay designed to measure the activity of Cdc25A protein phosphatase. This 96-well assay is useful for screening inhibitors and modulators of Cdc25A activity in HTS. The kit includes all necessary components, including recombinant, human Cdc25A (catalytic domain), for use in preinvestigational drug discovery assays. This assay kit is for research use only and not for use in human, diagnostic, or therapeutic procedures. Storage
    [Show full text]
  • Genetic Alterations of Protein Tyrosine Phosphatases in Human Cancers
    Oncogene (2015) 34, 3885–3894 © 2015 Macmillan Publishers Limited All rights reserved 0950-9232/15 www.nature.com/onc REVIEW Genetic alterations of protein tyrosine phosphatases in human cancers S Zhao1,2,3, D Sedwick3,4 and Z Wang2,3 Protein tyrosine phosphatases (PTPs) are enzymes that remove phosphate from tyrosine residues in proteins. Recent whole-exome sequencing of human cancer genomes reveals that many PTPs are frequently mutated in a variety of cancers. Among these mutated PTPs, PTP receptor T (PTPRT) appears to be the most frequently mutated PTP in human cancers. Beside PTPN11, which functions as an oncogene in leukemia, genetic and functional studies indicate that most of mutant PTPs are tumor suppressor genes. Identification of the substrates and corresponding kinases of the mutant PTPs may provide novel therapeutic targets for cancers harboring these mutant PTPs. Oncogene (2015) 34, 3885–3894; doi:10.1038/onc.2014.326; published online 29 September 2014 INTRODUCTION tyrosine/threonine-specific phosphatases. (4) Class IV PTPs include Protein tyrosine phosphorylation has a critical role in virtually all four Drosophila Eya homologs (Eya1, Eya2, Eya3 and Eya4), which human cellular processes that are involved in oncogenesis.1 can dephosphorylate both tyrosine and serine residues. Protein tyrosine phosphorylation is coordinately regulated by protein tyrosine kinases (PTKs) and protein tyrosine phosphatases 1 THE THREE-DIMENSIONAL STRUCTURE AND CATALYTIC (PTPs). Although PTKs add phosphate to tyrosine residues in MECHANISM OF PTPS proteins, PTPs remove it. Many PTKs are well-documented oncogenes.1 Recent cancer genomic studies provided compelling The three-dimensional structures of the catalytic domains of evidence that many PTPs function as tumor suppressor genes, classical PTPs (RPTPs and non-RPTPs) are extremely well because a majority of PTP mutations that have been identified in conserved.5 Even the catalytic domain structures of the dual- human cancers are loss-of-function mutations.
    [Show full text]
  • FOXM1 Is a Transcriptional Target of Erα and Has a Critical Role in Breast
    Oncogene (2010) 29, 2983–2995 & 2010 Macmillan Publishers Limited All rights reserved 0950-9232/10 $32.00 www.nature.com/onc ORIGINAL ARTICLE FOXM1 is a transcriptional target of ERa and has a critical role in breast cancer endocrine sensitivity and resistance J Millour1, D Constantinidou1, AV Stavropoulou1, MSC Wilson1, SS Myatt1, JM-M Kwok1, K Sivanandan1, RC Coombes1, RH Medema2, J Hartman3, AE Lykkesfeldt4 and EW-F Lam1 1Department of Surgery and Cancer, Imperial College London, London, UK; 2Department of Medical Oncology, University Medical Center Utrecht, Utrecht, The Netherlands; 3Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden and 4Department of Breast Cancer Research, Institute of Cancer Biology, Danish Cancer Society, Copenhagen, Denmark In this study, we investigated the regulation of FOXM1 Introduction expression by estrogen receptor a (ERa) and its role in hormonal therapy and endocrine resistance. FOXM1 Breast cancer is the second most prevalent cause of protein and mRNA expression was regulated by ER- cancer death in the western hemisphere and displays a ligands, including estrogen, tamoxifen (OHT) and fulves- complex aeitology. The forkhead box (FOX) family trant (ICI182780; ICI) in breast carcinoma cell lines. member FOXM1 was previously reported to be elevated Depletion of ERa by RNA interference (RNAi) in MCF-7 in breast cancer as well as in carcinomas of other origins cells downregulated FOXM1 expression. Reporter gene (Pilarsky et al., 2004). FOXM1 is expressed in prolifer- assays showed that ERa activates FOXM1 transcription ating adult tissues and in response to injury or repair through an estrogen-response element (ERE) located (Korver et al., 1997a, b; Ye et al., 1999; Leung et al., within the proximal promoter region.
    [Show full text]
  • The Cdc25b Phosphatase Is Essential for the G2/M Phase Transition in Human Cells
    Journal of Cell Science 111, 2445-2453 (1998) 2445 Printed in Great Britain © The Company of Biologists Limited 1998 JCS3777 The cdc25B phosphatase is essential for the G2/M phase transition in human cells Christiane Lammer1, Sybille Wagerer1, Rainer Saffrich2, Daniel Mertens1, Wilhelm Ansorge2 and Ingrid Hoffmann1,* 1FS 6 Angewandte Tumorvirologie (F0400), Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 242, 69120 Heidelberg, Germany 2Biochemical Instrumentation Programme, European Molecular Biology Laboratory, Meyerhofstr. 1, 69117 Heidelberg, Germany *Author for correspondence (e-mail: [email protected]) Accepted 15 June; published on WWW 30 July 1998 SUMMARY Cdc25 phosphatases play key roles in cell cycle progression cdc25B is activated through phosphorylation during S- by activating cyclin-dependent kinases. In human cells, phase. Using a cell duplication, microinjection assay we cdc25 proteins are encoded by a multigene family, show that ablation of cdc25B function by specific antibodies consisting of cdc25A, cdc25B and cdc25C. While cdc25A blocks cell cycle progression in Hs68 cells by inhibition of plays a crucial role at the G1/S phase transition, cdc25C is entry into mitosis. Cdc25B function neither plays a role in involved in the dephosphorylation and activation of the later stages of mitosis nor for the inititation of DNA mitotic kinase, cdc2/cyclinB. In addition, cdc25C itself is replication. These results indicate that cdc25B is a mitotic regulated by cdc2/cyclinB which then creates a positive regulator that might act as a ‘starter phosphatase’ to feedback loop that controls entry into mitosis. In this study initiate the positive feedback loop at the entry into M phase. we show that the activity of cdc25B appears during late S phase and peaks during G2 phase.
    [Show full text]
  • Microrna-21 Negatively Regulates Cdc25a and Cell Cycle Progression in Colon Cancer Cells
    Published OnlineFirst October 13, 2009; DOI: 10.1158/0008-5472.CAN-09-1996 Published Online First on October 13, 2009 as 10.1158/0008-5472.CAN-09-1996 Molecular Biology, Pathobiology, and Genetics microRNA-21 Negatively Regulates Cdc25A and Cell Cycle Progression in Colon Cancer Cells Peng Wang,1 Fangdong Zou,1 Xiaodong Zhang,2 Hua Li,1 Austin Dulak,1 Robert J. Tomko, Jr.,1 John S. Lazo,1 Zhenghe Wang,2 Lin Zhang,1 and Jian Yu1 1University of Pittsburgh Cancer Institute, and Departments of Pathology and Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania and 2Department of Genetics and Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio Abstract Deregulation of miRNAs contributes to human pathogenesis microRNAs (miRNA) are small noncoding RNAs that partic- including cancer (2). For example, aberrant expression of miRNAs, ipate in diverse biological processes by suppressing target including miR-21, miR-17-92, miR-15, miR-16, and let-7, has been gene expression. Altered expression of miR-21 has been reported in cancer (3). Furthermore, a substantial number of reported in cancer. To gain insights into its potential role in miRNA genes are located in the fragile sites in the genomic regions tumorigenesis, we generated miR-21 knockout colon cancer that are frequently amplified, deleted, or rearranged in cancer, cells through gene targeting. Unbiased microarray analysis providing plausible mechanisms of deregulated expression (4, 5). combined with bioinformatics identified cell cycle regulator A theme is emerging that a miRNA can be considered either a Cdc25A as a miR-21 target. miR-21 suppressed Cdc25A tumor suppressor or an oncogene depending on its targets in different tissues and cell types (6–8).
    [Show full text]
  • Arylstibonic Acids Are Potent and Isoform-Selective Inhibitors Of
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Spiral - Imperial College Digital Repository Arylstibonic acids are potent and isoform-selective inhibitors of Cdc25a and Cdc25b phosphatases Lok Hang Mak a,b, Jessica Knott a,b, Katherine A. Scott c,d, Claire Scott e, Gillian F. Whyte a,b, Yu Ye f, David Mann b,c, Oscar Ces a,b, James Stivers f, Rudiger Woscholski a,b,* a Department of Chemistry, Imperial College London, Exhibition Road, London SW7 2AZ, UK b Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, UK c Division of Molecular Biosciences, Imperial College London, Exhibition Road, London SW7 2AZ, UK d Drug Discovery Centre, Imperial College London, St Dunstan’s Road, London, W6 8RP, UK e Division of Cell and Molecular Biology, Imperial College London, Exhibition Road, London SW7 2AZ, UK f Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205 *Corresponding author: Tel: +44 (0) 2075945305, Email: [email protected] Keywords: Arylstibonic acids, protein tyrosine phosphatase, Cdc25 inhibitor Abstract In this study, a library of arylstibonic acids were screened as potential protein tyrosine phosphatase inhibitors. Two compounds, namely 13778 and P6949 were identified as potent Cdc25 phosphatase inhibitors, an important key regulator of the eukaryotic cell cycle. These arylstibonic acids were also tested against other members of the protein tyrosine phosphatase family and were found to display good specificity and potency for Cdc25 phosphatases. Introduction Phosphatases are important regulators of many cellular functions, which in turn impact disease and human health.
    [Show full text]
  • Loss of the Forkhead Transcription Factor Foxm1 Causes Centrosome Amplification and Mitotic Catastrophe
    Research Article Loss of the Forkhead Transcription Factor FoxM1 Causes Centrosome Amplification and Mitotic Catastrophe Diane R. Wonsey and Maximillian T. Follettie Department of Discovery Medicine, Wyeth Research, Cambridge, Massachusetts Abstract with a targeted deletion of FoxM1 in the liver show decreased Expression of the forkhead transcription factor FoxM1 bromodeoxyuridine (BrdUrd) incorporation and fewer mitotic cells correlates with proliferative status in a variety of normal compared with wild-type controls following partial hepatectomy (6). and transformed cell types. Elevated expression of FoxM1 has Conversely, premature expression of FoxM1 in transgenic mice been noted in both hepatocellular carcinoma and basal cell accelerates hepatocyte DNA replication and the expression of cell carcinoma. However, whether FoxM1 expression is essential cycle regulatory proteins following partial hepatectomy (7). for the viability of transformed cells is unknown. We report Consistent with a role in proliferation, elevated expression of here that the expression of FoxM1 is significantly elevated in FoxM1 has been reported in both basal cell carcinoma (8) and in primary breast cancer. Microarray analysis shows that FoxM1 hepatocellular carcinoma (9). In addition, FoxM1 expression is re- regulates genes that are essential for faithful chromosome quired for the proliferative expansion of hepatocellular carcinoma segregation and mitosis, including Nek2, KIF20A, and CENP-A. in a mouse model of tumor induction (10). The observation that a p19ARF peptide fragment physically interacts with FoxM1, sup- Loss of FoxM1 expression generates mitotic spindle defects, delays cells in mitosis, and induces mitotic catastrophe. Time- presses FoxM1 transcriptional activity, and inhibits FoxM1- lapse microscopy indicates that depletion of FoxM1 generates enhanced anchorage-independent growth (10) suggests that cells that enter mitosis but are unable to complete cell FoxM1 may be an attractive target for cancer therapy.
    [Show full text]