[Mechanism of apoptosis induced by SIRT1 deacetylase inhibitors in human breast cancer MCF-7 drug-resistant cells].
The mechanism of apoptosis induced by SIRT1 deacetylase inhibitors in both human breast cancer MCF-7 and MCF-7 doxorubicin-resistant cells was studied. MTT assay was used to detect growth-inhibitory effect on the cells. Protein expression was detected by Western blotting. Chromatin condensation was detected by a fluorescent microscope after Hoechst 33342 staining. Cell cycle distribution was analyzed with flow cytometry. Apoptotic cells were detected with Annexin V staining. Nicotinamide (NAM) and Sirtinol, two SIRT1 deacetylase inhibitors, exhibited the similar growth-inhibitory effects on MCF-7/DOX cells and MCF-7 cells, but no potentiation of DOX activities. The arrest at G2/M phase was detected by flow cytometry in both MCF-7 and MCF-7/DOX cells after NAM treatment. Activation of caspase pathway in MCF-7 cells, such as the cleavages of PARP, caspase-6, -7, -9, were observed after exposure to NAM 50 mmol x L(-1), accompanied by the occurrence of chromatin condensation and Annexin V positive cells. However, the cleavages of PARP, caspase-6 and -7 in MCF-7/DOX cells delayed after exposure to NAM for 24 h and obviously increased at 48 h with appearance of chromatin condensation and Annexin V positive cells. SIRT1 deacetylase inhibitors show no cross resistance to MCF-7 drug-resistant cells, and the similar growth-inhibitory actions of them to MCF-7 sensitive and drug-resistant cells by which it is mediated by activation of apoptotic caspase pathway.
Li
Yong
Y
Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
Xu
Rong
R
Zhang
Xiu-min
XM
Li
Dian-dong
DD
He
Qi-yang
QY
D017209:Apoptosis / Q000187:drug effects*; D001549:Benzamides / Q000494:pharmacology; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D020169:Caspases / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D009284:Naphthols / Q000494:pharmacology; D009536:Niacinamide / Q000494:pharmacology; D056564:Sirtuin 1 / Q000037:antagonists & inhibitors*
D001549:Benzamides; D004791:Enzyme Inhibitors; D009284:Naphthols; C439060:sirtinol; D009536:Niacinamide; D004317:Doxorubicin; D020169:Caspases; C447939:SIRT1 protein, human; D056564:Sirtuin 1