Tissue and plasma co-expression of microRNA let-7g-5p in colorectal cancer patients

Background: Tumor-associated microRNAs (miRNAs) have been detected in cancer, though whether plasma miRNAs could be a potential biomarker for cancers need to be more clear. We aimed to determine tissue and plasma expression levels of miRNA let-7g-5p, potentially predicting the clinical characteristics of patients with colorectal cancer (CRC).Methods: A total of 62 cancer tissue and peripheral blood samples and 32 controls were included in the study. After total RNA extraction, quantitative real-time PCR was used to detect the relative expression of let-7g-5p.Results: The expression level of miR-let-7g-5p was down-regulated in CRC tissue compared to the non-tumor tissues (2.32±0.38 vs. 6.86±0.55, p<0.001). Moreover, a significant down-regulation of let-7g-5p was detected in plasma samples from CRC patients than in those of the controls (0.97±0.21 vs. 1.15±0.11, p<0.001). Further analysis showed a possible relationship between the tissue and plasma levels of let-7g-5p. Correlation analysis detected a significant association between expression levels of tissue and plasma let-7g-5p (r=0.56; p<0.001).Conclusion: The down-regulation of let-7g-5p in plasma and tissue is matched in CRC and may be served promisingly as a potential biomarker.