Sophocarpine inhibits tumor progression by antagonizing the PI3K/AKT/mTOR signaling pathway in castration-resistant prostate cancer

Objective: The objective of this study was to investigate the inhibitory effect of sophocarpine on the progression of castration-resistant prostate cancer (CRPC) and the underlying molecular mechanism. Methods: DU145 and PC3 cells (two CRPC cell lines), incubated with different concentrations of sophocarpine, were used. Cell Counting Kit-8 assay, real-time cellular analysis, and colony formation assay were conducted to evaluate the proliferation of CRPC cells. Cytometry flow analysis was performed to evaluate the apoptosis rate of CRPC cells. Wound healing and Transwell invasion assays were performed and the levels of the epithelial-mesenchymal transition (EMT)-related proteins were determined to analyze cell migration and invasion abilities. A xenografted tumor model of nude mice was used to examine the anti-cancer effect of sophocarpine on CRPC. Western blotting was performed to evaluate the activities of the PI3K/AKT/mTOR signaling pathway both in cells and tumor tissues. Results: In vitro tests showed that sophocarpine suppressed the proliferation of CRPC cells, reduced the migration and invasion abilities, and increased the apoptosis rate. In vivo, sophocarpine decreased the weight and volume of tumor tissues. Mechanically, sophocarpine exerted its anti-cancer effects by inactivating PI3K/AKT/mTOR signaling. Conclusion: Sophocarpine inhibited the progression of CRPC by downregulating the PI3K/AKT/mTOR signaling pathway and showed a potential to be an anti-cancer agent against CRPC.