204P - Attenuated MMR and CIN pathway promote CRC progression through CDC25A upregulation: role of DNMT inhibitors

Date 17 December 2016
Event ESMO Asia 2016 Congress
Session Poster lunch
Topics Colon Cancer
Rectal Cancer
Translational Research
Presenter Koyel Banerjee
Citation Annals of Oncology (2016) 27 (suppl_9): ix53-ix67. 10.1093/annonc/mdw581
Authors K. Banerjee1, C. Pradhan2, K. Chaudhuri2, A. Mukhopadhyay1, D. Dam1, R. Bhattacharya1
  • 1Molecular Biology, Netaji Subhas Chandra Bose Cancer Research Institute, 700016 - Kolkata/IN
  • 2Human Genetics, Indian Institute of Chemical Biology, 700032 - Kolkata/IN

Abstract

Background

Colorectal cancer (CRC) is mainly attributed to CIN (APC) and defective MMR (MLH1, MSH2) pathway genes, although these pathways are not mutually exclusive. Interestingly, CDC25A, the G2/M checkpoint regulator and one of the important targets of both pathways (1, 2) is found to be over expressed in CRC. Thus, aim of our present study was to analyze the RNA and protein expression status of APC, MSH2, MLH1, CDC25A and thus identifying potential CRC biomarkers necessitating therapeutic interventions.

Methods

Twenty CRC biopsy specimens and their adjacent normal tissues were taken for the study. Immunohistochemistry to identify the expression of the candidate TSGs of both pathways were carried out following standard protocol. RNA expression analysis for all the candidate genes in tumor and adjacent normal tissues were carried out by qRT-PCR following standard protocol (3).

Results

RNA expression analysis of the candidate genes in primary tumor showed overall 60% (n = 20) of the primary tumors to have reduced expression of MMR or APC genes, indicating either genetic or epigenetic alterations of these pathways in those cases (Figure 1). Protein expression analysis showed reduced or no expression of MMR proteins (MLH1, MSH2) in 15% of the tumors. Moderate cytoplasmic and scanty nuclear expression of MMR proteins were observed in 85% of the tumors (Figure 2, 3), indicating their functional attenuation. Majority of the patients showed (80%) high cytoplasmic expression of APC, whereas moderate or low nuclear intensity was found in 10% of patients (Figure 4). Validation of the expression of the candidate genes in HT-29 cells showed, at low concentration (

Conclusions

Expression analysis of the candidate genes in primary tumor showed that the hallmark TSGs of MMR and CIN pathway, viz MLH1, MSH2 and APC respectively, are mostly attenuated in primary CRCs. Synergistic upregulation of TSGs and down regulation of CDC25A in HT-29, at low dose (

Clinical trial indentification

NA

Legal entity responsible for the study

N/A

Funding

Netaji subhas Chandra Bose Cancer Research Institute

Disclosure

All authors have declared no conflicts of interest.