Novel dipeptidyl proteasome inhibitors overcome Bcl-2 protective function and selectively accumulate the cyclin-dependent kinase inhibitor p27 and induce apoptosis in transformed, but not normal, human fibroblasts
B. An et al., Novel dipeptidyl proteasome inhibitors overcome Bcl-2 protective function and selectively accumulate the cyclin-dependent kinase inhibitor p27 and induce apoptosis in transformed, but not normal, human fibroblasts, CELL DEAT D, 5(12), 1998, pp. 1062-1075
It has been suggested that overexpression of the Bcl-2 oncoprotein in human
cancer cells contributes to their resistance to apoptosis induced by chemo
therapy, We report here that a novel dipeptidyl proteasome inhibitor, CEP16
12, at low concentrations rapidly induces apoptosis in human Jurkat T cells
overexpressing Bcl-2 and also in ail human prostate, breast, tongue and br
ain tumor cell lines we have tested to date, without exception. In contrast
, etoposide, a standard anticancer drug, fails to kill these cells when emp
loyed under the same conditions. The apoptosis-inducing abilities of CEP161
2 and its analogous compounds match precisely their order for inhibition of
the proteasome chymotrypsin-like activity. CEP1612-induced apoptosis is p5
3-independent, inhibitable by a tetrapeptide caspase inhibitor, and associa
ted with accumulation of the cyclin-dependent kinase inhibitors p21 and p27
. Furthermore, CEP1612 selectively accumulates p27 and induces apoptosis in
simian virus 40-transformed, but not the parental normal, human fibroblast
s. Proteasome inhibitors such as those investigated herein might therefore
have potential use as novel anticancer drugs.