MM-associated circular RNA downregulates microRNA-19a through methylation to suppress proliferation of pancreatic adenocarcinoma cells.

Opposite roles of circular RNA MM-associated circular RNA (circ-MYBL2) have been observed in different malignancies, and its role in pancreatic adenocarcinoma (PA) is unknown. Our preliminary sequencing data revealed its inverse correlation with microRNA-19a (miR-19a). This study was performed to explore the role of circ-MYBL2 in PA and its crosstalk with miR-19a. The accumulation of circ-MYBL2 and miR-19a in PA was detected by RT-qPCR. Participation of circ-MYBL2 in the regulation of miR-19a and its RNA gene methylation was studied with an overexpression assay, followed by RT-qPCR and MSP analyses. The role of miR-19a and circ-MYBL2 in PA cell proliferation and movement was evaluated using the BrdU assay and the Transwell assay, respectively. Downregulation of circ-MYBL2 and upregulation of miR-19a were observed in PA. In PA cells, circ-MYBL2 decreased the accumulation of miR-19a but increased its RNA gene methylation. Overexpression of circ-MYBL2 decreased PA cell proliferation and movement, while overexpression of miR-19a showed an opposite effect. In addition, circ-MYBL2 suppressed the role of miR-19a in cell proliferation, migration, and invasion. In conclusion, circ-MYBL2 was downregulated in PA and it downregulated miR-19a through methylation to suppress PA cell proliferation.