Involvement of mitochondrial pathway in Taxol-induced apoptosis of human T24 bladder cancer cells.
We examined a human urothelial cancer T24 cell line, which was exposed to clinically achievable concentrations of Taxol and detected the lethal effect of Taxol as measured by a cytotoxic dose-response curve. Marked nuclear condensation and the fragmentation of chromatin were observed by DAPI stain, DNA ladder formation, and flow cytometry at an LC(90)concentration of 0.8 microg/ml Taxol, which also induced a G2/M arrest. In response to Taxol-treatment, caspase-9 activity increased at 8 h, and both caspase-2 and -3 activities were increased twofold relative to control cultures at 16 h. Moreover, treatment with the broad-spectrum caspase inhibitor (z-VAD-fmk) or the caspase-9 specific inhibitor (z-LEHD-fmk) effectively protected T24 cells against Taxol-triggered apoptosis. Furthermore, the phosphorylation of Bcl-2 and Bcl-X(L) proteins in Taxol treated cells was detected at 8 h. In contrast, Taxol had no effect on the levels of Fas and FasL proteins and neither antagonistic, anti-Fas antibody affected Taxol-induced apoptosis. These results suggest that, following the phosphorylation of Bcl-2 and Bcl-X(L)proteins, Taxol-induced apoptosis is induced through the mitochondria-dependent pathway in T24 cells.
Yuan
Sheau-Yun
SY
Department of Surgery, Taichung Veterans General Hospital, No 160, section 3, Chung-Gang Road, Taichung, Taiwan.
Hsu
Shih-Lan
SL
Tsai
Kan-Jen
KJ
Yang
Chi-Rei
CR
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000502:physiology*; D020169:Caspases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D053222:Fas Ligand Protein; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism; D008928:Mitochondria / Q000502:physiology*; D008938:Mitosis / Q000187:drug effects; D017239:Paclitaxel / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000473:pathology / Q000503:physiopathology*; D051020:bcl-X Protein; D019014:fas Receptor / Q000378:metabolism
D000972:Antineoplastic Agents, Phytogenic; C494811:BCL2L1 protein, human; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; D019014:fas Receptor; D020169:Caspases; D017239:Paclitaxel