BACKGROUND/AIMS: Hepatocellular carcinoma is a very common malignancy and is highly chemoresistant to currently available chemotherapeutic agents. We isolated a marine prostanoid, bromovulone III, from soft coral Clavularia viridis and found that it displayed effective anti-tumor activity in human hepatocellular carcinoma. The anti-tumor mechanism has been delineated in this study. METHODS: Anti-tumor efficacy and apoptotic cell death were examined by sulforhodamine B and Hoechst 33342 assays. Rhodamine 123 was used to measure the change of mitochondrial membrane potential. Immunoprecipitation and Western blotting detect the involvement of several apoptosis-related proteins. Electron microscopic examination detects the morphological change of mitochondria and endoplasmic reticulum (ER). RESULTS: Bromovulone III primarily induced mitochondria-related activation of caspase-9 and -3 in several tumor types, such as prostate cancer PC-3 and acute promyelocytic leukemia HL-60 cells. However, it primarily induced the activation of m-calpain, caspase-12, and transcription factor CHOP/GADD153 in hepatocellular carcinoma Hep3B cells, suggesting the involvement of ER stress. Furthermore, a secondary mitochondrial swelling and depolarization of mitochondrial membrane potential were subsequently triggered after ER stress, suggesting the crosstalk between ER and mitochondria. CONCLUSIONS: It is suggested that bromovulone III induces apoptosis in Hep3B cells through a mechanism that induces ER stress and leads to activation of CHOP/GADD153 and caspase-12.
BACKGROUND/AIMS: Hepatocellular carcinoma is a very common malignancy and is highly chemoresistant to currently available chemotherapeutic agents. We isolated a marine prostanoid, bromovulone III, from soft coral Clavularia viridis and found that it displayed effective anti-tumor activity in humanhepatocellular carcinoma. The anti-tumor mechanism has been delineated in this study. METHODS: Anti-tumor efficacy and apoptotic cell death were examined by sulforhodamine B and Hoechst 33342 assays. Rhodamine 123 was used to measure the change of mitochondrial membrane potential. Immunoprecipitation and Western blotting detect the involvement of several apoptosis-related proteins. Electron microscopic examination detects the morphological change of mitochondria and endoplasmic reticulum (ER). RESULTS:Bromovulone III primarily induced mitochondria-related activation of caspase-9 and -3 in several tumor types, such as prostate cancer PC-3 and acute promyelocytic leukemia HL-60 cells. However, it primarily induced the activation of m-calpain, caspase-12, and transcription factor CHOP/GADD153 in hepatocellular carcinoma Hep3B cells, suggesting the involvement of ER stress. Furthermore, a secondary mitochondrial swelling and depolarization of mitochondrial membrane potential were subsequently triggered after ER stress, suggesting the crosstalk between ER and mitochondria. CONCLUSIONS: It is suggested that bromovulone III induces apoptosis in Hep3B cells through a mechanism that induces ER stress and leads to activation of CHOP/GADD153 and caspase-12.
Authors: Diana C West; Yan Qin; Quinn P Peterson; Diana L Thomas; Rahul Palchaudhuri; Karen C Morrison; Pamela W Lucas; Amy E Palmer; Timothy M Fan; Paul J Hergenrother Journal: Mol Pharm Date: 2012-04-27 Impact factor: 4.939