{'fraction_non_alphanumeric': 0.03397508493771234, 'fraction_numerical': 0.01812004530011325, 'mean_word_length': 5.425454545454546, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Interplay of reactive oxygen species, intracellular Ca2+ and mitochondrial homeostasis in the apoptosis of prostate cancer cells by deoxypodophyllotoxin

The limited treatment option for recurrent prostate cancer and the eventual resistance to conventional chemotherapy drugs has fueled continued interest in finding new anti‐neoplastic agents of natural product origin. We previously reported anti‐proliferative activity of deoxypodophyllotoxin (DPT) on human prostate cancer cells. Using the PC‐3 cell model of human prostate cancer, the present study reveals that DPT induced apoptosis via a caspase‐3‐dependent pathway that is activated due to dysregulated mitochondrial function. DPT‐treated cells showed accumulation of the reactive oxygen species (ROS), intracellular Ca  i2+ surge, increased mitochondrial membrane potential (MMP, ΔΨm), Bax protein translocation to mitochondria and cytochrome c release to the cytoplasm. This resulted in caspase‐3 activation, which in turn induced apoptosis. The antioxidant N‐acetylcysteine (NAC) reduced ROS accumulation, MMP and Ca  i2+ surge, on the other hand the Ca2+ chelator BAPTA inhibited the Ca  i2+ overload and MMP without affecting the increase of ROS, indicating that the generation of ROS occurred prior to Ca2+ flux. This suggested that both ROS and Ca  i2+ signaling play roles in the increased MMP via Ca  i2+ ‐dependent and/or ‐independent mechanisms, since ΔΨm elevation was reversed by NAC and BAPTA. This study provides the first evidence for the involvement of both ROS‐ and Ca  i2+ ‐activated signals in the disruption of mitochondrial homeostasis and the precedence of ROS production over the failure of Ca2+ flux homeostasis. J. Cell. Biochem. 114: 1124–1134, 2013. © 2012 Wiley Periodicals, Inc.