In vitro study of miRNA-369-3p targeting TCF4 regulating the malignant biological behavior of colon cancer cells

BACKGROUND: Colorectal carcinoma (CRC) is a common malignant tumor of the digestive tract. It is characterized by a high degree of malignancy, early metastasis and poor prognosis. Studies have shown the effect of miR-369-3p on the biological function of a variety of tumors. However, the mechanism by which miR-369-3p and its potential target genes participate in the pathogenesis of CRC has not been elucidated. This study aims to study the relationship between miR-369-3p and transcription factor 4 (TCF4), to reveal the mechanism of the occurrence and development of CRC, and to provide a promising target for the treatment of CRC. METHODS: Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the miR-369-3p levels in CRC tissues and cells. miR-369-3p mimics and/or TCF4 overexpression vectors were transfected into SW480 cells. The expression of miR-369-3p and TCF4 mRNA was detected using RT-qPCR. Bioinformatics analysis predicted the binding site of miR-369-3p to the TCF4 3'UTR, and the targeting relationship was verified by a dual luciferase reporter gene assay. Cell proliferation and invasion were investigated by labeled immunofluorescence assay using BrdU antibody and Transwell assay. The oxidative stress ability of cells was determined by commercial kits. The levels of proteins related to cell proliferation and invasion were measured by western blotting. RESULTS: The level of miR-369-3p was significantly down-regulated in CRC tissues and cell lines, especially in SW480 cells (P<0.05). The expression of TCF4 was negatively correlated with that of miR-369-3p. High levels of miR-369-3p targeting TCF4 suppressed cell proliferation and downregulated the protein expression of Ki67 and PCNA (P<0.05). Overexpressed miR-369-3p binding TCF4 inhibited cell invasion and decreased the protein levels of vascular endothelial growth factor (VEGF) and E-cadherin (P<0.05). Furthermore, upregulation of miR-369-3p increased the activity of superoxide dismutase (SOD) while decreasing the content of malondialdehyde (MDA) and activity of lactate dehydrogenase (LDH) by blocking the expression of TCF4 (P<0.05). CONCLUSIONS: MiR-369-3p inhibits the proliferation, invasion and oxidative stress of CRC cells by targeting TCF4, thus defining miR-369-3p as a potential target for the diagnosis and treatment of CRC.