Silibinin (SB), a flavonoid extracted from milk thistle seeds, has been found to exert antitumor effects in numerous tumor types. Our previous study reported that SB had anti-metastatic effects in prostate cancer (PCa). However, the exact underlying molecular mechanisms remain to be determined. The present study aimed to investigate the effects of SB on the migration, invasion and epithelial-mesenchymal transition (EMT) of castration-resistant PCa (CRPC) cells using wound healing, Transwell assays, and western blotting. The results revealed that SB treatment significantly inhibited the migration and invasion of CRPC cell lines. Moreover, SB was confirmed to activate autophagy, as determined using LC3 conversion, LC3 turnover and LC3 puncta assays. Further mechanistic studies indicated that the expression levels of Yes-associated protein (YAP) were downregulated in an autophagy-dependent manner after SB treatment. In addition, the SB-induced autophagic degradation of YAP was associated with the anti-metastatic effects of SB in CRPC. In conclusion, the findings of the present study suggested that SB might inhibit the migration, invasion and EMT of PCa cells by regulating the autophagic degradation of YAP, thus representing a potential novel treatment strategy for metastatic CRPC.

Long non-coding RNAs (lncRNAs) have been considered as biomarkers for the carcinogenesis and development of various cancers. However, the prognostic significance of lncRNAs in renal cell carcinoma (RCC) remains unclear. This study aimed to determine the predictive ability of lncRNAs in clear cell RCC (ccRCC). Among the cohort of kidney renal clear cell carcinoma (KIRC) of the The Cancer Genome Atlas (TCGA), 525 patients were enrolled in our study. Expression of lncRNAs based on RNAseq was obtained from TCGA. Kaplan-Meier prognostic analysis and a Cox proportional hazards regression model were used to assess related factors. The lncRNA signature was then validated in an independent cohort of an additional 60 ccRCC patients. Hierarchical clustering of the KIRC TCGA dataset identified 26 differentially expressed lncRNAs (11 down-regulated and 15 up-regulated) using average linkage clustering. Kaplan-Meier survival analysis identified 30 statistically significant lncRNAs that strongly predicted prognosis, with 4 ccRCC-specific lncRNAs (TCL6, PVT1, MIR155HG, and HAR1B) being differentially expressed and correlating significantly with OS. Patients assigned to the high-risk group were associated with poor OS compared with patients in the low-risk group (HR = 2.57; 95%CI, 1.89-3.50; p < 0.001). This finding was validated in the Tongji Hospital cohort, and the four-lncRNA signature was shown to be significantly predictive of ccRCC prognosis (p < 0.001). In this study, we constructed an applicable four-lncRNA-based classifier as a reliable prognostic and predictive tool for OS in patients with ccRCC.

Hsp70 (heat shock protein 70) plays critical roles in cancer cell proliferation and apoptosis. Recently, accumulating evidences have demonstrated the cancer promoting effects of Hsp70 in bladder cancer. The development of novel therapeutic approaches targeting Hsp70 thus received great attention from researchers. In this study, we demonstrated that silibinin, a natural polyphenolic flavonoid isolated from the milk thistle, targeted Hsp70 by inhibiting its transcription in bladder cancer cells. We also demonstrated that knockdown of endogenous Hsp70 enhanced silibinin-induced apoptosis, while overexpression of exogenous Hsp70 could partially reverse the effects of silibinin-induced cell apoptosis. Furthermore, we found that silibinin could activate HSF1/Hsp70-regulated mitochondrial apoptotic pathway. Mechanically, silibinin inhibited the interaction between Apaf-1 and Hsp70, thus increasing the recruitment of pro caspase-9. Results from in vivo study demonstrated that silibinin suppressed the growth of bladder cancer xenografts, which was accompanied with the activation of caspase-3 and downregulation of HSF1 and Hsp70. Taken together, our data indicates that silibinin induces mitochondrial apoptosis via inhibiting HSF1/Hsp70 pathway and also suggests the therapeutic potential of silibinin in the treatment of bladder cancer.