Effect of miR-449a-mediated Notch signaling pathway on the proliferation, apoptosis and invasion of papillary thyroid carcinoma cells

The present study aimed to investigate the effect of miR-449a-mediated Notch signaling pathway on the proliferation, apoptosis and invasion of papillary thyroid carcinoma cells. Human papillary thyroid carcinoma cell line TPC-1 was selected, and cells were grouped and transfected: Control group (without any treatment), negative control (NC) group (transfection with NC plasmid), miR-449a mimic group (transfection with miR-449a mimic), miR-449a inhibitor group (transfection with miR-449a inhibitor), DAPT group (addition of γ-secretase inhibitor DAPT to inhibit the Notch signaling pathway), and miR-449a inhibitor + DAPT group (transfection with miR-449a inhibitor and addition of DAPT). The target relationship between miR-449a and Notch1 was detected by dual-luciferase reporter assay. qRT-PCR and western blotting were used to assess the expression of miR-449a, Notch1 and Jagged1 in cells. Cell proliferation was detected using EdU; the cell cycle and apoptosis were detected by flow cytometry; cell invasion ability was detected by Transwell assay. PCNA, MMP-2, MMP-9, Bcl-2 and Bax mRNA and protein expression were assessed by qRT-PCR and western blotting. The results revealed that miR-449a negatively regulated Notch1. Compared with the control group, there was significantly increased miR-449a expression in the miR-449a mimic group, and there was significantly decreased expression of Notch1, Jagged1, PCNA, MMP-2, MMP-9 and Bcl-2, increased Bax, reduced cell proliferation, increased G1-phase cell fraction, decreased S-phase cell fraction, an increased apoptosis rate, and decreased invasion ability in the miR-449a mimic group and DAPT group (all P<0.05). However, the results in the miR-449a inhibitor group were the opposite of those in miR-449a mimic group (all P<0.05). There was no significant difference in cell proliferation, apoptosis and invasion in the NC group and miR-449a inhibitor + DAPT group compared to the control group (all P>0.05). miR-449a overexpression can inhibit Notch signaling pathway, thereby inhibiting the proliferation and invasion of papillary thyroid carcinoma cells and promoting cell apoptosis.