title: Apoptosis of human hepatocellular carcinoma cell (HepG2) induced by cardiotoxin III through S-phase arrest.
abstract: Cytotoxin III (CTX III), a basic polypeptide with 60 amino acid residues isolated from Naja naja atra venom, have potential therapeutic activity in tumor therapy. However, the therapeutic effect in solid tumor treatment with CTX III are still largely unknown. In the present study, we investigated whether CTX III affects cell growth and cell cycle progression of hepatocellular carcinoma cell (HepG2). We found that the proliferation of HepG2 cell was inhibited by CTX III, to some extent, in a time- and dose-dependent manner (IC50 2.58microg/ml at 24h). Flow cytometric analysis and annexin V labeling also demonstrated that CTX III increased the percentage of apoptotic cells being associated with cell cycle arrest at S-phase. Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blot revealed that cyclin D1, cyclin A and cyclin E, which involved in cell apopotosis and cell cycle progression, were down regulated both at transcription and translation levels. CTX III-induced caspase-8, -9 and caspase-3 activation, generation of truncated Bid, releasing of cytochrome c and the change of Bcl-2/Bax ratio on protein and mRNA levels. These findings demonstrated that cyclin D1, cyclin B and cyclin A down-regulation, change of Bcl-2/Bax ratio and caspase-8 and -9 activation contribute to CTX III-induced HepG2 cell apoptosis.
authors.affiliation: School of Life Science, University of Science and Technology of China, Anhui province, PR China.
authors.forename: Xingyong
authors.initials: X
authors.lastname: Chen
authors.forename: Ping
authors.initials: P
authors.lastname: Lv
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.forename: Kangsen
authors.initials: K
authors.lastname: Xu
mesh_terms: D000970:Antineoplastic Agents / Q000302:isolation & purification / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D020169:Caspases / Q000378:metabolism; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004179:Cobra Cardiotoxin Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D045304:Cytochromes c / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016196:S Phase / Q000187:drug effects*
chemical_list: D000970:Antineoplastic Agents; D004179:Cobra Cardiotoxin Proteins; C082202:cardiotoxin III, Naja naja atra; D045304:Cytochromes c; D020169:Caspases