Introduction Colorectal cancer (CRC) progression is associated with suppression of host cell mediated immunity (CMI) and local immune escape mechanisms (1.2). The aim of the study was to assess immune function in terms of the DNA methylation and expression of TNF, IFN- γ and FOXP3 and to identify potential targets for immunotherapy in CRC.
Methods 60 CRC patients and 15 matched controls were recruited. TaqMan quantitative PCR (qRT-PCR) was performed for relative quantitation of expression of TNF, IFNG, FOXP3 in the PBMC and tumour. Methylation specific PCR was performed to determine the methylation status. MSI status was determined using microsatellite primers BAT25 and BAT26.
Results TNF expression was suppressed in CRC tumours (median fold change 0.48). IFN- γ was found to be suppressed in the PBMC (median 0.34) of CRC patients. Tumours showed enhanced expression of FOXP3 (median 2.2). Expression of FOXP3 in tumours was significantly higher when the size of the tumour was more than 50mm (p = 0.005). Methylated TNFpromoter and FOXP3cpg correlated significantly with suppression of TNF and FOXP3 respectively. Significant TNF suppression (p = 0.002) was noted in the PBMC of patients with MSI. No correlation was observed between the MSI status and DNA methylation status of our study genes.
Conclusion Our study identified changes in protein expression which correlated with the methylation status. It demonstrates the influence of DNA methylation on gene expression that could act as a biomarker for future immunotherapy with possible role for demethylating agents.
Disclosure of Interest None Declared.
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