Lin Wang1, Tao Hu2, Jing Shen2, Lin Zhang2, Ruby Lok-Yi Chan2, Lan Lu2, Mingxing Li2, Chi Hin Cho2, William Ka Kei Wu3. 1. School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Lo Kwee-Seong Integrated Biomedical Sciences Building, Shatin, NT, Hong Kong, China. Electronic address: wanglinster@gmail.com. 2. School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Lo Kwee-Seong Integrated Biomedical Sciences Building, Shatin, NT, Hong Kong, China. 3. Department of Anaesthesia and Intensive Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
Abstract
BACKGROUND: Dihydrotanshinone I (DHTS) was previously reported to exhibit the most potent anti-cancer activity among several tanshinones in colon cancer cells. Its cytotoxic action was reactive oxygen species (ROS) dependent but p53 independent. PURPOSE: To further study the anti-cancer activity of DHTS and its molecular mechanisms of action in colon cancer both in vitro and in vivo. METHODS: Caspase activity was detected by fluorescence assay. Apoptosis was detected by flow cytometry and TUNEL assay. Protein levels were analyzed by western blotting. Knockdown of target gene was achieved by siRNA transfection. Formation of LC3B puncta and activation of caspase-3 were detected by confocal fluorescence microscope. In vivo anti-colon cancer activity of DHTS was observed in xenograft tumors in NOD/SCID mice. RESULTS: Anti-colon cancer activity of DHTS by inducing apoptosis and autophagy was observed both in vitro and in vivo. Mitochondria mediated caspase dependent pathway was essential in DHTS-induced cytotoxicity. The apoptosis induced by DHTS was suppressed by knockdown of apoptosis inducing factor (AIF), inhibition of caspase-3/9 but was increased after knockdown of caspase-2. Meantime, knockdown of caspase-2, pretreatment with Z-VAD-fmk or NAC (N-Acety-L-Cysteine) efficiently inhibited the autophagy induced by DHTS. A crosstalk between cytochrome c and AIF was also reported. CONCLUSION: DHTS-induced caspase and ROS dependent apoptosis and autophagy were mediated by mitochondria in colon cancer. DHTS could be a promising leading compound for the development of anti-tumor agent or be developed as an adjuvant drug for colon cancer therapy.
BACKGROUND:Dihydrotanshinone I (DHTS) was previously reported to exhibit the most potent anti-cancer activity among several tanshinones in colon cancer cells. Its cytotoxic action was reactive oxygen species (ROS) dependent but p53 independent. PURPOSE: To further study the anti-cancer activity of DHTS and its molecular mechanisms of action in colon cancer both in vitro and in vivo. METHODS: Caspase activity was detected by fluorescence assay. Apoptosis was detected by flow cytometry and TUNEL assay. Protein levels were analyzed by western blotting. Knockdown of target gene was achieved by siRNA transfection. Formation of LC3B puncta and activation of caspase-3 were detected by confocal fluorescence microscope. In vivo anti-colon cancer activity of DHTS was observed in xenograft tumors in NOD/SCIDmice. RESULTS: Anti-colon cancer activity of DHTS by inducing apoptosis and autophagy was observed both in vitro and in vivo. Mitochondria mediated caspase dependent pathway was essential in DHTS-induced cytotoxicity. The apoptosis induced by DHTS was suppressed by knockdown of apoptosis inducing factor (AIF), inhibition of caspase-3/9 but was increased after knockdown of caspase-2. Meantime, knockdown of caspase-2, pretreatment with Z-VAD-fmk or NAC (N-Acety-L-Cysteine) efficiently inhibited the autophagy induced by DHTS. A crosstalk between cytochrome c and AIF was also reported. CONCLUSION:DHTS-induced caspase and ROS dependent apoptosis and autophagy were mediated by mitochondria in colon cancer. DHTS could be a promising leading compound for the development of anti-tumor agent or be developed as an adjuvant drug for colon cancer therapy.
Authors: Dan Zhang; Bo Zhang; Li-Xin Zhou; Jun Zhao; You-You Yan; Yang-Ling Li; Jian-Mei Zeng; Lin-Ling Wang; Bo Yang; Neng-Ming Lin Journal: Acta Pharmacol Sin Date: 2016-09-26 Impact factor: 6.150