N6-Methyladenosine modified circ-NAB1 modulates cell cycle and epithelial-mesenchymal transition via CDKN3 in endometrial cancer

m6A modified circ-NAB1/miR-876-3p/CDKN3 axis in EC

Abstract

Endometrial cancer (EC) is a common malignant tumor in the female reproductive system. Circular RNAs (circRNAs) and N6-methyladenosine (m⁶A) modification are widely involved in cancer progression. Nevertheless, the cross-talk between circ-NAB1 and m⁶A as well as the biological functions of circ-NAB1 in EC remain unclear. Circ-NAB1 was observed to be upregulated in EC tissues and cells by RT-qPCR. MeRIP and RNA pull-down assays were utilized for detecting the m⁶A modification of circ-NAB1. The interaction between circ-NAB1 and RNAs was also detected. Colony formation, transwell, flow cytometry, and western blot were utilized for measuring EC cell behaviors. Mechanically, we proved the m⁶A demethylase alkylation repair homolog protein 5 (ALKBH5) can mediate circ-NAB1 expression through an m⁶A-YTHDF2-dependent manner. Circ-NAB1 overexpression can promote cell proliferation, migration, invasion, epithelial-mesenchymal transition (EMT) process, and cell cycle through functional assays. Circ-NAB1 knockdown exerts the opposite function on EC cells. Furthermore, we proved that circ-NAB1 can sponge miR-876-3p to upregulate the target gene cyclin-dependent kinase inhibitor 3 (CDKN3) in EC cells. CDKN3 overexpression can reverse the impacts of circ-NAB1 depletion on EC cell behaviors. Collectively, we proved that ALKBH5-mediated m⁶A modification of circ-NAB1 promoted EMT process and cell cycle in EC via targeting the miR-876-3p/CDKN3 axis.