title: G226, a novel epipolythiodioxopiperazine derivative, induces autophagy and caspase-dependent apoptosis in human breast cancer cells in vitro.
abstract: OBJECTIVE
  To investigate the effects of G226, a novel epipolythiodioxopiperazine derivative, on human breast cancer cells in vitro, and to explore its anticancer mechanisms.
  
  
  METHODS
  A panel of human breast cancer cell lines (MDA-MB-231, MDA-MB-468, MCF-7, ZR-75-30, BT474, BT549, SK-BR-3, T47D and HBL100) was examined. Cell proliferation was measured using sulforhodamine B assay, and cell apoptosis was detected with flow cytometry and caspase activity assay. Western blotting, immunofluorescence and targeted gene knockdowns were used to study autophagy in the cells.
  
  
  RESULTS
  G226 suppressed proliferation of the 9 breast cancer cell lines with a mean IC50 value of 48.5 nmol/L (the mean IC50 value of adriamycin, a reference compound, was 170.6 nmol/L). G226 induced dose-dependent apoptosis of MDA-MB-231 and MCF-7 cells, accompanied by markedly increased activities of caspase-8 and caspase-3/7, which were abolished by caspase inhibitors zVAD or zIETD. G226 also induced mitochondrial outer membrane permeabilization, resulted in the caspase-9 activation. Moreover, G226 dose-dependently enhanced the autophagy marker LC3-II and autophagy substrate p62 accumulation in the cells, which were co-localized with caspase-8. Silencing of p62 or LC3 partially diminished caspase-8 and subsequent caspase-3 activation. LC3 silencing partially reversed G226-induced apoptosis, but p62 silencing elicited a subtle effect on G226-induced apoptosis.
  
  
  CONCLUSIONS
  The novel epipolythiodioxopiperazine derivative G226 exerts potent anticancer action against human breast cancer cells in vitro, via triggering autophagy and caspase-dependent apoptosis.
authors: Institute of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors: Peng-xing
authors: PX
authors: He
authors: Beijing Institute of Pharmacology & Toxicology, Beijing 100190, China.
authors: Yong-sheng
authors: YS
authors: Che
authors: Institute of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors: Qiao-jun
authors: QJ
authors: He
authors: Division of Anti-tumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors: Yi
authors: Y
authors: Chen
authors: Division of Anti-tumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors: Jian
authors: J
authors: Ding
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry* / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D001940:Breast / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D020169:Caspases / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D054659:Diketopiperazines / Q000737:chemistry* / Q000494:pharmacology*; D004220:Disulfides / Q000737:chemistry* / Q000494:pharmacology*; D005260:Female; D006801:Humans; D010879:Piperazines
chemical_list: D000970:Antineoplastic Agents; D054659:Diketopiperazines; D004220:Disulfides; C000600490:G226 compound; D010879:Piperazines; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; C540279:11,11'-dideoxyverticillin A