DNA methylation regulated microRNA-200b in colorectal polyp and cancer tissues in Iranian population

Introduction: In recent years, colorectal cancer (CRC) incidence has been increasing to become a serious reason of mortality worldwide from cancers, with high rates in westernized societies and increasing rates in developing countries. Epigenetic modifications including changes in DNA methylation, histone modifications, and non-coding RNAs play a critical role in carcinogenesis. Aberrant DNA methylation is a common molecular feature in colorectal cancer (CRC). Hypermethylation of miR-200b promoter, as an epigenetic factor, involves in CRC. Methylation of miR-200b has been investigated in CRC and normal tissues but these study in colorectal polyps has evaluated fo the first time. This study investigated miR-200b methylation in colorectal adenomatous polyp, hyperplastic polyp and adenocarcinoma tissues. Materials and Methods In the recent study, miR-200b methylation was examined in 131 samples from 114 individuals, including 30 adenocarcinoma specimens, 17 tumor adjacent normal tissues, 78 primary lesions (55 adenomatous polyps and 23 hyperplastic polyps) and 6 healthy individuals. The methylation status of miR-200b promoter was considered by methylation-specific PCR. Results Methylation of miR-200b was observed in adenocarcinoma samples (86%) and adenomatous polyps (85%), while most of hyperplastic polyps were unmethylated (69.6%). Neither control individuals nor tumor adjacent normal tissues exhibited methylation in miR-200b promoter. Aberrant methylation of miR-200b was significantly more common in tumor tissues and adenomatous polyps than in hyperplastic polyps (p < 0.0001) and tumor adjacent normal tissues (p <0.0001). Conclusion Methylation status of miR-200b promoter was changed during CRC development and it may be identified as an attractive biomarker for early detection of the disease.

کلیدواژه ها:

miR-200b ، colorectal cancer ، polyp ، epigenetic ، methylation ، biomarker