Expression levels of microRNA-375 in colorectal carcinoma

MicroRNAs are small, non-coding RNAs of endogenous origin. They have been increasingly shown to have altered expressions in many cancer types. The expression levels of miR-375 have not been comprehensively investigated in colorectal cancer. In this study, total RNA was extracted from 95 pairs of colorectal cancer tissues and non-tumor adjacent tissues, as well as from three colorectal cancer cell lines (HT-29, HCT-116 and SW-620). After polyadenylation and reverse transcription, we determined the expression levels of miR-375 by real-time PCR and calculated the difference in expression using the 2-∆∆Ct method. We assessed the correlation between the expression levels of miR-375 and clinicopathological characteristics of colorectal cancer. miR-375 expression was frequently downregulated in the colorectal cancer tissues compared to the non-tumor counterparts (p<0.001; paired t-test). Moreover, a significantly low expression of miR-375 was also found in the colorectal cancer cell lines (HT-29, p=0.002; HCT-116, p<0.001; SW-620, p=0.004; paired t-test). However, there were no significant correlations between the low expression of miR-375 and tumor size, histological grade, pT stage, pN stage and pTNM stage (all P>0.05, non-parametric test; Mann-Whitney U test between two groups and Kruskal-Wallis H test for three or more groups). miR-375 may be involved in the carcinogenesis of colorectal cancers and may be a potential biomarker for colorectal cancers.