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Prostate cancers at the late stage of castration resistance are not responding well to most of current therapies available in clinic, reflecting a desperate need of novel treatment for this life-threatening disease. In this study, we evaluated the anti-cancer effect of a recently isolated natural compound Alternol in multiple prostate cancer cell lines with the properties of advanced prostate cancers in comparison to prostate-derived non-malignant cells. As assessed by trypan blue exclusion assay, a significant cell death was observed in all prostate cancer cell lines except DU145 but not in non-malignant (RWPE-1and BPH1) cells. Further analyses revealed that Alternol-induced cell death was an apoptotic response in a dose- and time-dependent manner, as evidenced by the appearance of apoptosis hallmarks such as Caspase-3 processing and PARP cleavage. Interestingly, Alternol-induced cell death was completely abolished by reactive oxygen species (ROS) scavengers, N-acetylcysteine (N-Ac) and dihydrolipoic acid (DHLA). We also demonstrated that the pro-apoptotic Bax protein was activated after Alternol treatment and was critical for Alternol-induced apoptosis. Animal xenograft experiments in nude mice showed that Alternol treatment largely suppressed tumor growth of PC-3 xenografts but not Bax-null DU-145 xenografts in vivo. These data suggest that Alternol might serve as a novel anticancer agent for late stage prostate cancer patient.

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