miR-199a/214 cluster enhances prostate cancer sensitiveness to nimotuzumab via targeting TBL1XR1.

Prostate cancer (PCa) is a significant health concern affecting men worldwide. Previous studies have shown that nimotuzumab, a drug targeting the epidermal growth factor receptor (EGFR), can effectively inhibit cancer progression. Here, we aimed to explore the role of miR-199a/214 cluster in mediating the inhibitory effect of nimotuzumab on the development of PCa. In this study, we conducted an MTT assay to assess cell proliferation and utilized flow cytometry to evaluate cell apoptosis and cell cycle arrest. To investigate the molecular mechanisms underlying the effects of nimotuzumab on prostate cancer development, we focused on the miR-199a-5p and miR-214-3p miRNA clusters. The TargetScan Human database was used to predict the binding sites between miR-199a-5p or miR-214-3p and the 3'-UTR of the transducin (β)-like 1 X-linked receptor 1 (TBL1XR1) mRNA. To confirm the direct interaction and binding between miR-199a-5p or miR-214-3p and the 3'-UTR of TBL1XR1 mRNA, we performed luciferase reporter assays. Our findings demonstrated that nimotuzumab exerted a significant dosage-dependent suppression of PCa cell proliferation and facilitated PCa cell apoptosis and cell cycle arrest. Concurrently, nimotuzumab obviously impeded the activity of Wnt/β-catenin and EGFR signaling pathways in PCa cells. We also observed downregulation of miR-199a-5p and miR-214-3p in PCa cells. Overexpression of miR-199a/214 cluster inhibited PCa cell viability and enhanced cell apoptosis. Furthermore, we found that miR-199a/214 cluster augmented the inhibitory effect of nimotuzumab on PCa cell proliferation and promoted its ability to induce apoptosis and cell cycle arrest. This effect was reversed upon TBL1XR1 overexpression, indicating that TBL1XR1 is involved in the regulatory pathway of miR-199a/214 and nimotuzumab in PCa cells. We further revealed that TBL1XR1 was overexpressed in PCa and was identified as a downstream target of the miR-199a/214 cluster. In nimotuzumab-treated PCa cells, the overexpression of miR-199a/214 markedly inhibited Wnt/β-catenin and EGFR signaling, and this effect was also rescued by TBL1XR1 overexpression. In summary, our data indicated that miR-199a/214 cluster play a crucial role in enhancing the inhibitory effect of nimotuzumab on PCa development by downregulating TBL1XR1 and modulating Wnt/β-catenin and EGFR signaling pathways. These findings offer a novel therapeutic approach for the treatment of prostate cancer.