1. Evaluation of CHK1 activation in vulvar squamous cell carcinoma and its potential as a therapeutic target in vitro
- Author
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Ruth Holm, Zhihui Wang, Jahn M. Nesland, Claes G. Tropé, Mette Førsund, and Ana Slipicevic
- Subjects
0301 basic medicine ,Cancer Research ,Vulvar Squamous Cell Carcinoma ,Cell ,Apoptosis ,Kaplan-Meier Estimate ,medicine.disease_cause ,0302 clinical medicine ,Phosphorylation ,RNA, Small Interfering ,Original Research ,Cancer Biology ,Aged, 80 and over ,Vulvar Neoplasms ,Cell Cycle ,Middle Aged ,Cell cycle ,Prognosis ,vulvar squamous cell carcinomas ,Immunohistochemistry ,medicine.anatomical_structure ,Oncology ,Chk1 inhibitor ,030220 oncology & carcinogenesis ,Carcinoma, Squamous Cell ,Female ,Adult ,Transcriptional Activation ,DNA damage ,03 medical and health sciences ,Cell Line, Tumor ,Biomarkers, Tumor ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,CHEK1 ,Protein Kinase Inhibitors ,Aged ,Proportional Hazards Models ,Retrospective Studies ,business.industry ,Vulvar cancer ,medicine.disease ,030104 developmental biology ,siRNA ,Checkpoint Kinase 1 ,Cancer research ,business ,Carcinogenesis ,DNA Damage - Abstract
CHK1 is an important regulator of the cell cycle and DNA damage response, and its altered expression has been identified in various tumors. Chk1 inhibitors are currently being evaluated as monotherapy and as potentiators of chemotherapy in clinical settings. However, to our knowledge, no previous study has investigated either the activation status or the therapeutic potential of CHK1 targeting in vulvar cancer. Therefore, we examined the expression status of activated CHK1 forms pCHK1Ser345 , pCHK1Ser317 , pCHK1Ser296 , and pCHK1Ser280 in 294 vulvar squamous cell carcinomas (VSCC) using immunohistochemistry and analyzed their relationships with various clinicopathological variables and clinical outcome. To aid translation of preclinical studies, we also assessed cell sensitivity to the Chk1 inhibition in two vulvar cancer cell lines. Compared to the levels of pCHK1Ser345 , pCHK1Ser317 , pCHK1Ser296 , and pCHK1Ser280 in normal vulvar squamous epithelium, high nuclear pCHK1Ser345 expression was found in 57% of vulvar carcinomas, whereas low nuclear pCHK1Ser317 , pCHK1Ser296 , and pCHK1Ser280 expressions were observed in 58%, 64%, and 40% of the cases, respectively. Low levels of pCHK1Ser317 and pCHK1Ser280 in the nucleus correlated significantly with advanced tumor behaviors and aggressive features. None of pCHK1Ser345 , pCHK1Ser317 , pCHK1Ser296 , and pCHK1Ser280 forms were identified as prognostic factors. In vitro inhibition of CHK1 by small molecular inhibitors or siRNA reduced viability by inducing DNA damage and apoptosis of vulvar cancer cell lines. In summary, we conclude that cellular functions regulated by CHK1 are phosphorylation/localization-dependent and deregulation of CHK1 function occurs in VSCC and might contribute to tumorigenesis. Targeting CHK1 might represent as a useful antitumor strategy for the subgroup of VSCC harboring p53 mutations.
- Published
- 2018
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