Apoptotic mechanisms in T47D and MCF-7 human breast cancer cells

Abstract

To investigate the mechanisms underlying apoptosis in breast cancer cells, staurosporine was used as an apoptotic stimulus in the human breast cancer cell lines MCF-7 and T47D. Staurosporine induced dose and time dependent increases in DNA fragmentation which was abrogated by z-VAD-fmk. MCF-7 cells did not express caspase-3, suggesting that DNA fragmentation occurred in the absence of caspase-3 and that other caspases may be involved. Staurosporine induced DEVDase activity in T47D cells suggesting the involvement of caspase-3 and/or caspase-7, yet there was no DEVDase activity in MCF-7 cells, probably ruling out the involvement caspase-7. However, staurosporine induced the cleavage of pro-caspase-6 in MCF-7 cells, but not in T47D cells. Caspase dependent PARP cleavage was detected in MCF-7 cells at 3 h, whereas only partial PARP cleavage was detected in T47D cells and then only after 24 h. Moreover, staurosporine led to cytochrome c release at 2 h in MCF-7 cells and 6 h in T47D cells. In addition, a time dependent and caspase-independent reduction of the mitochondrial transmembrane potential was observed; which appeared to occur after the release of cytochrome c. Translocation of Bax from the cytosol to mitochondria was observed in both cell types, and this preceded cytochrome c release in both T47D and MCF-7 cells. Apoptotic events in both cell types differ temporally, involving activation of different caspases and mitochondrial changes.

Evidence for colorectal cancer cell specificity of aspirin effects on NFκB signalling and apoptosis

“…These results contrast with some previous reports of NSAID-induced growth inhibition and apoptosis in breast and endometrial cancer cells (Noguchi et al, 1995;Planchon et al, 1995;Han et al, 1998;Arango et al, 2001), but these differences are reconciled by considering that these studies used NSAIDs other than aspirin (Noguchi et al, 1995;Planchon et al, 1995;Han et al, 1998), while others only observed apoptosis after long exposures (48 -96 h) to high concentrations of salicylate out with the therapeutic range (Sotiriou et al, 1999;Arango et al, 2001). The non-CRC cell lines are susceptible to other apoptosis-inducing agents and NFkB activators such as staurosporine and TNFa, respectively, indicating that these cell lines are not generally resistant to apoptosis or NFkB modulation (Mooney et al, 2002;Tang et al, 2002). The observation that aspirin decreased cell viability in one of the three breast cancer cell lines (T47D) is in keeping with epidemiological data that suggest a lesser protective effect of NSAIDs against breast cancer.…”

Autophagy delays apoptotic death in breast cancer cells following DNA damage

“…The overt PCD II response in MCF-7 cells may be due to lack of caspase-3 activity and possible defects in apoptosome formation/ caspase-9 activation, although studies have shown that restoration of caspase-3 expression only partially restores apoptosis in these cells. 11 Furthermore, breast cancers expressing normal caspase-3, such as T47D, also mount an autophagic response to a variety of therapeutics, including DNA-damaging agents (Figure 8 and Mooney et al 33 ).…”

c-Abl and Arg tyrosine kinases regulate lysosomal degradation of the oncoprotein Galectin-3

“…These findings are supported by an earlier report that STS induces the apoptosis of MCF-7, a caspase 3-deficient cell line, by the activation of caspase 6. 28 Moreover, Gal3 and Gal3(Y79FY118F) were expressed in c-Abl/Arg-depleted cells (Supplementary Figure 4a). In (Figure 6e).…”