[Adriamycin and mitomycin dose-dependently downregulate X-kinked inhibitor of apoptosis protein in human bladder cancer cells].
OBJECTIVE
To investigate the efficacy of inducing apoptosis in human bladder cancer cells by adriamycin and mitomycin and relevant mechanism.


METHODS
Human bladder cancer cells of the lines RT4, MGH-U1, FJ, and T24 were cultured. Adriamycin of the concentrations of 0.1, 1, and 10 microg/ml, and mitomycin of the concentrations of 0.01, 0.1, and 1 microg/ml were added into the culture fluid respectively. CCK-8 colorimetric assay was used to detect the survival rates of the cells so as to select the cell line sensitive and tolerable to the drugs. Flow cytometry was used to detect the cell apoptosis. Western blotting was used to detect the levels of X-kinked inhibitor of apoptosis protein (XIAP) and the cleavage of caspase-3 precursor.


RESULTS
It was found that RT4 cells were the most sensitive and the T24 cells were the most tolerable to adriamycin and mitomycin. Treated with adriamycin of the concentrations of 0.1, 1, and 10 microg/ml for 24 hours, the apoptotic rates of the RT4 cells were 15.3% +/- 4.3%, 29.3% +/- 6.4%, and 45.0% +/- 5.5% respectively; and the apoptotic rates of the T24 cells were 7.3% +/- 3.1%, 12.5% +/- 4.3%, and 18.2% +/- 6.3% respectively, all significantly lower than those of the RT4 cells (P < 0.05 or P < 0.01). Treated with mitomycin of the concentrations of 0.01, 0.1, and 1 microg/ml for 24 hours, the apoptotic rates of the RT4 cells were 12.7% +/- 2.9%, 31.3% +/- 4.4%, and 48.9% +/- 5.8% respectively, and the apoptotic rates of the RT4 cells were 7.2% +/- 3.3%, 15.5% +/- 5.2%, and 21.2% +/- 4.4% respectively, all significantly lower than those of the RT4 cells (all P < 0.05). The XIAP expression was not significantly different in these 4 cell lines before the adriamycin and mitomycin treatment. After the treatment of adriamycin and mitomycin, the expression of XIAP was down-regulated dose-dependently, however, being weaker in the T24 cells than in the RT4 cells; and caspase-3 precursor cleavage was enhanced, however, being weaker in the T24 cells too.


CONCLUSIONS
Adriamycin and mitomycin dose-dependently kill the human bladder cancer cells. Such cytotoxic effect may be realized through inducing the cell apoptosis which is associated with the down-regulation of XIAP and cleavage of caspase-3 precursor.
Yin
Zhen-fei
ZF
Department of Urology, First Hospital pf Peking University, Beijing 100034, China.
Li
Ming
M
Lai
Yong-qing
YQ
Yuan
Yi-ming
YM
Liu
Gang
G
Chen
Liang
L
Gan
Lin
L
Na
Yan-qun
YQ
D000903:Antibiotics, Antineoplastic / Q000008:administration & dosage / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D015251:Epirubicin / Q000008:administration & dosage / Q000494:pharmacology; D006801:Humans; D016685:Mitomycin / Q000008:administration & dosage / Q000494:pharmacology; D001749:Urinary Bladder Neoplasms / Q000378:metabolism* / Q000473:pathology; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000378:metabolism*
D000903:Antibiotics, Antineoplastic; D051636:X-Linked Inhibitor of Apoptosis Protein; D015251:Epirubicin; D016685:Mitomycin