Platycodin D (PD) regulates LncRNA-XIST/miR-335 axis to slow down bladder cancer progression in vitro and in vivo.

Recently, increasing evidences indicated that Platycodin D (PD) served as an effective anti-tumor drug for cancer treatment in clinic. However, the molecular mechanisms are still unclear. In the present study, we proved that PD regulated LncRNA-XIST/miR-335 axis to hamper the development of bladder cancer in vitro and in vivo. Mechanistically, PD inhibited malignant phenotypes, including cell proliferation, invasion, migration and epithelial-mesenchymal transition (EMT), and promoted cell apoptosis in bladder cancer cells in a time- and dose-dependent manner. In addition, the following experiments validated that PD inhibited LncRNA-XIST expressions, while increased miR-335 expression levels in bladder cancer cells. Next, by conducting the dual-luciferase reporter gene system assay and RNA pull-down assay, we validated that LncRNA-XIST inhibited miR-335 expressions through acting as RNA sponges, and the promoting effects of PD stimulation on miR-335 levels were abrogated by upregulating LncRNA-XIST. Interestingly, both silencing LncRNA-XIST and miR-335 overexpression enhanced the inhibiting effects of PD on the malignant phenotypes in bladder cancer cells. Consistently, the xenograft tumor-bearing mice models were established, and the data indicated that PD slowed down tumor growth and inhibited tumorigenesis in vivo, which were also aggravated by downregulating LncRNA-XIST. In general, analysis of data proved that targeting LncRNA-XIST/miR-335 axis was novel to enhance the anti-tumor effects of PD in bladder cancer in vitro and in vivo, and this study provided alternative therapeutic strategies for bladder cancer treatment in clinic.