RESUMO
AIMS: This study set out to examine the expression and methylation levels of miR-486-5p/miR-34c-5p and its mechanism of action based on the microRNA methylation level of circulating tumor cells (CTCs) in colorectal cancer (CRC) through clinical data and tissue detection. METHODS: EGFR and EpCAM immunophospholipid magnetic spheres (EpCAM-IML/EGFR-IML) were synthesized by the thin film method to capture CTCs in peripheral blood. The expression of miR-486-5p/miR-34c-5p was detected via real-time fluorescent quantitative PCR (RT-PCR). Methylation-specific PCR was implemented to detect the methylation level of miR-486-5p/miR-34c-5p, and 5-Aza-dC was used for demethylation treatment to detect the effect of changes in methylation levels on the tumor cells development. Cell Counting Kit-8 (CCK-8) analysis, transwell assay, and flow cytometry were used to determine the effects of demethylation and overexpression on the proliferation, invasion, migration, and apoptosis of CRC cells. RESULTS: The results showed that the expression and methylation levels of the miR-486-5p/miR-34c-5p isolated from CTCs were low and the methylation level was high in tumor cells and tissues. In CRC cell lines, demethylation and overexpression of miR-486-5p/miR-34c-5p could effectively inhibit the proliferation, invasion and migration of tumor cells, and facilitate tumor apoptosis (p < 0.05). CONCLUSION: The constructed CTCs sorting system has characteristics of high specificity and high sensitivity, is a supplement to tissue samples, and has guiding significance for the clinical rational use of drugs and personalized therapy.