Methyltransferase 3 beta (DNMT3B) inhibition by decitabine promotes endometrial carcinoma cell apoptosis by autophagy induction

Abstract

Autophagy regulates endometrial cancer cell apoptosis and inhibits endometrial cancer development; however, the specific underlying mechanisms are unclear. The effects of DNA methylation on endometrial cancer cell autophagy were explored in HEC-1B cells using decitabine, a DNA methylase inhibitor. Real-time fluorescence quantitative PCR (RT-qPCR) and western blot (WB) analyses were used to detect the mRNA and protein expression of DNA methylase (DNMT3B), autophagy-related genes LC3B and Beclin-1, and apoptosis-related genes Bax and Bcl-2. High-purity and high-quality RNA was obtained by nano-magnetic bead extraction, to ensure highly accurate RT-qPCR and WB results. MTT cell viability assay, scratch assay, and Transwell migration assay were utilized to detect the proliferation and migration of HEC-1B cells. The results showed that decitabine significantly inhibited the expression of DNMT3B protein and mRNA, with 25 μM decitabine being the most effective. In subsequent experiments, this concentration of decitabine was used. The low DNMT3B expression significantly inhibited the expression of Beclin-1 and LC3B proteins (***P <0.001 and *P <0.05) and mRNA (*P <0.05 and *P <0.05). Decitabine promoted the mRNA and protein expression of apoptotic factor Bax (*P < 0.05 and *P < 0.05), while inhibiting the mRNA protein expression of anti-apoptotic factor Bcl-2 (***P <0.001 and *P <0.05). MTT assay results showed decreased proliferation of HEC-1B cells following inhibition of DNMT3B expression by decitabine, which was significantly different from that of the NC group (*P <0.05). The results of the cell scratch and Transwell migration assays showed reduced migration ability of HEC-1B cells compared to that observed in the NC group (**P <0.01 and *P <0.05). These results show that decitabine inhibits DNMT3B expression, and low DNMT3B levels regulate the expression of autophagy- and apoptosis-related factors, thereby inhibiting the proliferation and migration of endometrial cancer cells.