title: Effect of triptolide on focal adhesion kinase and survival in MCF-7 breast cancer cells.
abstract: Triptolide, a diterpene from Tripterygium wilfordii, has been shown to have potent anticancer activity, exerting its effects through multiple molecular targets and signaling pathways. Yet, its effect on focal adhesion kinase (FAK), a non-receptor tyrosine kinase overexpressed in breast cancer that regulates cellular adhesion and survival, has not been reported. The current study is the first to report on the effect of triptolide on FAK expression, cell adhesion and survival using MCF-7 breast cancer cells. Triptolide significantly reduced MCF-7 anchorage-independent growth in a concentration-dependent manner. Cell rounding and detachment from culture plates were observed as early as 8 h, with significant cell detachment observed after 24 h of triptolide treatment. The adhesion potential of triptolide-treated MCF-7 cells to Matrigel was also compromised. Triptolide induced concentration- and time-dependent cleavage of FAK and PARP, which was dependent on caspase activation. The pan-caspase inhibitor, zVAD-fmk, was the only inhibitor that could significantly reduce FAK and PARP cleavage and cell detachment. However, the presence of zVAD-fmk failed to significantly reverse triptolide-induced cell death. Finally, triptolide-induced FAK cleavage was specific to MCF-7 cells, as no cleaved FAK was observed in MDA-MB-231 cells. In conclusion, our data present the first evidence of triptolide-mediated induction of FAK cleavage that correlates with cell detachment and loss of adhesion potential to the extracellular matrix.
authors.affiliation: Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore 117543, Singapore.
authors.forename: Bee-Jen
authors.initials: BJ
authors.lastname: Tan
authors.forename: Bee-Huey
authors.initials: BH
authors.lastname: Tan
authors.forename: Gigi N C
authors.initials: GN
authors.lastname: Chiu
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D002448:Cell Adhesion / Q000187:drug effects; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004224:Diterpenes / Q000494:pharmacology*; D004852:Epoxy Compounds / Q000494:pharmacology; D005260:Female; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D010616:Phenanthrenes / Q000494:pharmacology*
chemical_list: D018906:Antineoplastic Agents, Alkylating; D004224:Diterpenes; D004852:Epoxy Compounds; D010616:Phenanthrenes; C001899:triptolide; D051416:Focal Adhesion Protein-Tyrosine Kinases