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.