The E2F-regulated gene Chk1 is highly expressed in triple-negative estrogen receptor /progesterone receptor /HER-2 breast carcinomas.

We previously showed that checkpoint kinase 1 (Chk1) and Claspin, two DNA-damage checkpoint proteins, were down-regulated by 1,25-dihydroxyvitamin D(3), a known inhibitor of cell proliferation. In the present study, we aimed to investigate the transcriptional regulation of Chk1 and Claspin and to study their expression levels in human breast cancer tissue. Transient transfection experiments in MCF-7 breast cancer cells showed that promoter activities of Chk1 and Claspin were regulated by the E2F family of transcription factors. Subsequently, transcript levels of Chk1, Claspin, and E2F1 were determined by quantitative reverse transcriptase-PCR analysis in 103 primary invasive breast carcinomas and were compared with several clinicopathologic variables in breast cancer. A strong correlation was found between Chk1 and Claspin transcript levels. Transcript levels of Chk1, Claspin, and E2F1 were highest in histologic grade 3 tumors and in tumors in which the expression of estrogen receptor (ER) and progesterone receptor (PR) was lost. Moreover, Chk1 expression was significantly elevated in grade 3 breast carcinomas showing a triple-negative ER-/PR-/HER-2- phenotype compared with other grade 3 tumors. Further research is warranted to validate the use of Chk1 inhibitors in triple-negative breast carcinomas for which treatment strategies are limited at present.

[1]  K. Marchal,et al.  1α,25-Dihydroxyvitamin D3-induced down-regulation of the checkpoint proteins, Chk1 and Claspin, is mediated by the pocket proteins p107 and p130 , 2007, The Journal of Steroid Biochemistry and Molecular Biology.

[2]  Philip M. Long,et al.  Breast cancer classification and prognosis based on gene expression profiles from a population-based study , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[3]  Edward A. Sausville,et al.  The Chk1 Protein Kinase and the Cdc25C Regulatory Pathways Are Targets of the Anticancer Agent UCN-01* , 2000, The Journal of Biological Chemistry.

[4]  F. Vikhanskaya,et al.  Characterization of the 5’flanking Region of the Human chk1 Gene: Identification of E2F1 Functional Sites , 2003, Cell cycle.

[5]  Christian A. Rees,et al.  Molecular portraits of human breast tumours , 2000, Nature.

[6]  Roman Rouzier,et al.  Breast Cancer Molecular Subtypes Respond Differently to Preoperative Chemotherapy , 2005, Clinical Cancer Research.

[7]  A. Ashworth,et al.  Basal-like breast carcinomas: clinical outcome and response to chemotherapy , 2006, Journal of Clinical Pathology.

[8]  I. Ellis,et al.  Method for grading breast cancer. , 1993, Journal of clinical pathology.

[9]  C. Chini,et al.  Chk1 is required to maintain Claspin stability , 2006, Oncogene.

[10]  Gavin D. Grant,et al.  Common markers of proliferation , 2006, Nature Reviews Cancer.

[11]  A. McCourty,et al.  Immunohistochemical expression of cyclin D1, E2F‐1, and Ki‐67 in benign and malignant thyroid lesions , 2002, The Journal of pathology.

[12]  R. Tibshirani,et al.  Copyright © American Society for Investigative Pathology Short Communication Expression of Cytokeratins 17 and 5 Identifies a Group of Breast Carcinomas with Poor Clinical Outcome , 2022 .

[13]  E. Moler,et al.  CHIR-124, a Novel Potent Inhibitor of Chk1, Potentiates the Cytotoxicity of Topoisomerase I Poisons In vitro and In vivo , 2007, Clinical Cancer Research.

[14]  H. Komori,et al.  Identification of novel E2F1 target genes regulated in cell cycle-dependent and independent manners , 2006, Oncogene.

[15]  W. Foulkes,et al.  The Basal Phenotype of BRCA1-Related Breast Cancer: Past, Present and Future , 2006 .

[16]  Meijuan Huang,et al.  Selective targeting of checkpoint kinase 1 in tumor cells with a novel potent oncolytic adenovirus. , 2006, Molecular therapy : the journal of the American Society of Gene Therapy.

[17]  D. Kletsas,et al.  Evaluation of claspin as a proliferation marker in human cancer and normal tissues , 2007, The Journal of pathology.

[18]  S. Lakhani,et al.  Metaplastic breast carcinomas are basal‐like tumours , 2006, Histopathology.

[19]  Ian O Ellis,et al.  Prognostic markers in triple‐negative breast cancer , 2007, Cancer.

[20]  J. Griffith,et al.  Human Claspin Is a Ring-shaped DNA-binding Protein with High Affinity to Branched DNA Structures* , 2004, Journal of Biological Chemistry.

[21]  A. Klein-Szanto,et al.  E2F-1: a proliferative marker of breast neoplasia. , 2000, Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology.

[22]  W. Gerald,et al.  EGFR gene amplification in breast cancer: correlation with epidermal growth factor receptor mRNA and protein expression and HER-2 status and absence of EGFR-activating mutations , 2005, Modern Pathology.

[23]  A. Rosenwald,et al.  Checkpoint kinase 1 (CHK1) protein and mRNA expression is downregulated in aggressive variants of human lymphoid neoplasms , 2005, Leukemia.

[24]  Mark R. Green,et al.  Targeting targeted therapy. , 2004, The New England journal of medicine.

[25]  G. Raab,et al.  Cell turnover in the "resting" human breast: influence of parity, contraceptive pill, age and laterality. , 1982, British Journal of Cancer.

[26]  Zhan Xiao,et al.  Selective Chk1 inhibitors differentially sensitize p53‐deficient cancer cells to cancer therapeutics , 2006, International journal of cancer.

[27]  Y. Pommier,et al.  Abrogation of Chk1-mediated S/G2 checkpoint by UCN-01 enhances ara-C-induced cytotoxicity in human colon cancer cells. , 2004, Acta pharmacologica Sinica.

[28]  S. Hirohashi,et al.  Large, central acellular zones indicating myoepithelial tumor differentiation in high-grade invasive ductal carcinomas as markers of predisposition to lung and brain metastases. , 2000, The American journal of surgical pathology.

[29]  Soo-Mi Kim,et al.  Claspin and the Activated Form of ATR-ATRIP Collaborate in the Activation of Chk1* , 2004, Journal of Biological Chemistry.

[30]  R. Gelber,et al.  Ki‐67 expression in breast carcinoma , 2003, Cancer.

[31]  S. Elledge,et al.  Human Claspin works with BRCA1 to both positively and negatively regulate cell proliferation. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[32]  M. Garrett,et al.  Targeting the cell division cycle in cancer: CDK and cell cycle checkpoint kinase inhibitors. , 2005, Current opinion in pharmacology.

[33]  Jiri Bartek,et al.  Cell-cycle checkpoints and cancer , 2004, Nature.

[34]  M. Ellis,et al.  Study of the biologic effects of lapatinib, a reversible inhibitor of ErbB1 and ErbB2 tyrosine kinases, on tumor growth and survival pathways in patients with advanced malignancies. , 2005, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[35]  Therese Sørlie,et al.  Molecular portraits of breast cancer: tumour subtypes as distinct disease entities. , 2004, European journal of cancer.

[36]  P. Clarke,et al.  Cleavage of Claspin by Caspase-7 during Apoptosis Inhibits the Chk1 Pathway* , 2005, Journal of Biological Chemistry.

[37]  A. Gown,et al.  Immunohistochemical and Clinical Characterization of the Basal-Like Subtype of Invasive Breast Carcinoma , 2004, Clinical Cancer Research.

[38]  A. Gown,et al.  Specificity of HercepTest in determining HER-2/neu status of breast cancers using the United States Food and Drug Administration-approved scoring system. , 1999, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[39]  R. Tibshirani,et al.  Gene expression patterns of breast carcinomas distinguish tumor subclasses with clinical implications , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[40]  C. Perou,et al.  Race, breast cancer subtypes, and survival in the Carolina Breast Cancer Study. , 2006, JAMA.

[41]  K. Siziopikou,et al.  The Challenging Estrogen Receptor‐Negative/ Progesterone Receptor‐Negative/HER‐2‐Negative Patient: A Promising Candidate for Epidermal Growth Factor Receptor‐Targeted Therapy? , 2006, The breast journal.

[42]  Haiying Zhang,et al.  Differential roles of checkpoint kinase 1, checkpoint kinase 2, and mitogen-activated protein kinase–activated protein kinase 2 in mediating DNA damage–induced cell cycle arrest: implications for cancer therapy , 2006, Molecular Cancer Therapeutics.

[43]  Jiri Bartek,et al.  Chk1 and Chk2 kinases in checkpoint control and cancer. , 2003, Cancer cell.

[44]  G. Ball,et al.  High‐throughput protein expression analysis using tissue microarray technology of a large well‐characterised series identifies biologically distinct classes of breast cancer confirming recent cDNA expression analyses , 2005, International journal of cancer.

[45]  Z. Tao,et al.  Chk1 inhibitors for novel cancer treatment. , 2006, Anti-cancer agents in medicinal chemistry.