Pancratistatin induces apoptosis and autophagy in metastatic prostate cancer cells

Abstract

The Amaryllidaceae alkaloid pancratistatin has been proven to selectively induce apoptotic cell death in a variety of human cancer cells with an insignificant effect on non-cancerous cells. In this study we report, for the first time, the effects of pancratistatin (PST) on models of metastatic prostate cancer. The effects of pancratistatin on prostate cancer DU145 and LNCaP cell lines was assessed by microscopy, enzymatic activity assays and Western blotting. Apoptosis was determined by nuclear condensation and caspase activation, and autophagy was observed by MDC staining and LC3 expression levels. Human prostate xenografts were used to test the potential therapeutic efficacy of intra-tumor administration of pancratistatin in vivo. Pancratistatin treatment reduced cell viability and induced apoptosis in androgen-responsive (LNCaP) and androgen-refractory (DU145) prostate cancer cell lines in a dose- and time-dependent manner, but with an insignificant effect on normal human fibroblast (NHF) cells at the effective dose. Increased reactive oxygen species production and collapse of mitochondrial membrane potential resulted from treatment with pancratistatin in both cancer cell lines. This study presents the novel finding that pancratistatin treatment caused decreased migration capacity and increased autophagy levels in metastatic prostate cancer cells. Importantly, in this proof-of-concept study, pancratistatin reduced the volume of xenograft tumors compared to control-treated animals, and was well-tolerated. Our results highlight the potential of pancratistatin for clinical development as a selective therapeutic for treatment of metastatic prostate cancer.