MicroRNA-93 mediates cabergoline resistance by targeting ATG7 in prolactinoma

Abstract

To date, the management of dopamine agonist (DA)-resistant prolactinomas remains a major clinical problem. Previously, we determined that miRNA-93 expression increases in DA-resistant prolactinomas; however, the role of miRNA-93 in the DA resistance remains largely unexplored. Hence, this study aimed to investigate the susceptibility of tumor cells to cabergoline (CAB) and the autophagy changes in MMQ and GH3 cells after miRNA-93 overexpression or inhibition. We used bioinformatics to identify the potential target of miRNA-93. Subsequently, we analyzed the correlation between miRNA-93 and autophagy-related 7 (ATG7) using protein expression analysis and luciferase assays. Furthermore, the change in the effect of miRNA-93 was measured after ATG7 overexpression. miRNA-93 expression was elevated in DA-resistant prolactinomas, whereas the expression of its identified target, ATG7, was downregulated. miRNA-93 overexpression suppressed the cytotoxic effect of CAB in MMQ and GH3 cells. In contrast, miRNA-93 downregulation enhanced CAB efficiency and promoted cell autophagy, eventually resulting in apoptosis. These results were further confirmed in in vivo xenograft models in nude mice. ATG7 overexpression could reverse the inhibitory effect of miRNA-93 on CAB treatment. Taken together, our results suggest that miRNA-93 mediates CAB resistance via autophagy downregulation by targeting ATG7 and serves as a promising therapeutic target for prolactinoma.