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Gossypol reduction of tumor growth through ROS‐dependent mitochondria pathway in human colorectal carcinoma cells
Author(s) -
Ko ChingHuai,
Shen ShingChuan,
Yang LiangYo,
Lin ChengWei,
Chen YenChou
Publication year - 2007
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.22910
Subject(s) - apoptosis , cytochrome c , microbiology and biotechnology , mitochondrion , chemistry , reactive oxygen species , biology , cancer research , biochemistry
Among 13 different cell lines, gossypol (GOS) showed the most potent cytotoxic effect against human colorectal carcinoma cells including HT29, COLO205, COLO320HSR and COLO320DM cells according to an MTT assay. The cytotoxic effect of GOS was mediated by its induction of apoptosis as characterized by the occurrence of DNA ladders, apoptotic bodies and chromosome condensation in both COLO205 and HT29 cells. Activation of caspase 3, 6, 8 and 9, but not caspase 1, accompanied by the appearance of cleaved fragments of PARP (85 kDa), and caspase 3 (p17/p15), was identified in GOS‐treated cells. Decreases in Bcl‐xL and phosphorylated Bad proteins were found in GOS‐treated cells. GOS induction of ROS production was detected by in vitro plasmid digestion, and an increase in the intracellular peroxide level was observed in GOS‐treated COLO205 cells by the DCHF‐DA assay. Antioxidants including N ‐acetyl‐ L ‐cysteine (NAC), catalase (CAT), tempol (TEM) and melatonin (MEL), but not allopurinol (ALL), pyrrolidine dithiocarbamate (PDTC) or diphenylene iodonium (DPI), significantly inhibited GOS‐induced Reactive oxygen species (ROS) production through blocking the occurrence of apoptosis. GOS induced mitochondrial dysfunction characterized by a loss of the mitochondria membrane potential via DiOC6 staining, and the release of cytochrome c (Cyt c) and apoptosis‐inducing factor (AIF) from mitochondria to the cytoplasm was observed. Removing mitochondria by ethidium bromide (EtBr) treatment significantly reduced the apoptotic effect of GOS in COLO205 cells. Furthermore, an intraperitoneal injection of GOS or gossypol acetic acid (GAA) significantly reduced the growth of colorectal carcinoma induced by a subcutaneous injection of COLO205 cells in nude mice. Results of the present study provide the first evidences demonstrating the in vitro and in vivo antitumor effects of GOS via an ROS‐dependent mitochondrial apoptosis in colorectal carcinoma. © 2007 Wiley‐Liss, Inc.