beta-lapachone induces growth inhibition and apoptosis in bladder cancer cells by modulation of Bcl-2 family and activation of caspases
Lee, J.I.; Choi, D.Y.; Chung, H.S.; Seo, H.G.; Woo, H.J.; Choi, B.T.; Choi, Y.H.
Experimental Oncology 28(1): 30-35
2006
ISSN/ISBN: 1812-9269 PMID: 16614704 Document Number: 600016
Aim: To study in vitro the molecular mechanism of apoptosis caused by P-lapachone, a quinone obtained from the bark of the lapacho tree (Tabebuia avellanedae).Materials and Methods: The study was carried out on human bladder carcinoma T24 cell line. Determination of cell viability was done using trypan blue exclusion method, apoptosis quantitative estimation - by DAPI staining and agarose gel electrophoresis for DNA fragmentation. Flow cytometry analysis, RT-PCR and Western blot analysis, colorimetric assay of caspase activity were applied as well.Results: It was found that in micromolar range of concentrations beta-lapachone inhibited the viability of T24 cells by inducing apoptosis, which could be proved by formation of apoptotic bodies and DNA fragmentation. Treatment of T24 cells with beta-lapachone resulted in a down-regulation of Bcl-2 expression and up-regulation of Bax expression. beta-lapachone- induced apoptosis was also associated with activation of caspase-3 and caspase-9, inhibition of IAP expression, and degradation of poly (ADP-ribose) polymerase, phospholipase C-gamma 1 and beta-catenin proteins. At the same time Fas and FasL levels were inhibited upon treatment with beta-lapachone in a concentration -dependent manner.Conclusion: beta-lapachone -induced apoptosis in T24 cells is mediated, at least in part, by the mitochondrial-signaling pathway.