Inhibition of proteasome activity by bortezomib in renal cancer cells is p53 dependent and VHL independent.
BACKGROUND
Antiproliferative effects of proteasome inhibitors are suggested to be primarily due to effects on nuclear factor-kappaB (NF-kappaB)-dependent pathways and the induction of apoptosis. The objective of this study was to elucidate the mechanistic basis for the antiproliferative effects of the proteasome inhibitor, bortezomib, in human clear cell renal cell cancer cells (CCRCC).


METHODS
von Hippel Lindau (VHL) mutation/methylation status and cytotoxic response to bortezomib was determined in a panel of CCRCC cell lines. Effects on target protein/gene expression and the role of p53 in bortezomib-mediated cytotoxicity, inhibition of proteasome activity, survivin transcript and protein expression as well as induction of p21 expression was determined in CCRCC that differed in their intrinsic sensitivity to bortezomib.


RESULTS
VHL status was not associated with cytotoxic response to bortezomib treatment. Cytotoxicity in cell lines that differed in intrinsic sensitivity to bortezomib correlated with sustained inhibition of proteasome activity, survivin expression and induction of p21 expression. Stable down-regulation of p53 expression by siRNA led to attenuation of bortezomib effects, survivin down-regulation and p21 induction, suggesting that cellular effects are p53-dependent.


CONCLUSIONS
These results demonstrate that the antiproliferative effects of bortezomib in CCRCC cells are VHL independent and dependent on pathways regulated by p53.
Vaziri
Susan A J
SA
1Clinical Pharmacology Program, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA.
Grabowski
Dale R
DR
Hill
Jason
J
Rybicki
Lisa R
LR
Burk
Robert
R
Bukowski
Ronald M
RM
Ganapathi
Mahrukh K
MK
Ganapathi
Ram
R
D017209:Apoptosis / Q000187:drug effects; D001897:Boronic Acids / Q000494:pharmacology*; D000069286:Bortezomib; D002292:Carcinoma, Renal Cell / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects; D020869:Gene Expression Profiling; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D007680:Kidney Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic / Q000235:genetics; D011480:Protease Inhibitors / Q000494:pharmacology*; D061988:Proteasome Inhibitors; D011719:Pyrazines / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D000077022:Survivin; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000235:genetics* / Q000378:metabolism
C107489:BIRC5 protein, human; D001897:Boronic Acids; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D011480:Protease Inhibitors; D061988:Proteasome Inhibitors; D011719:Pyrazines; D034741:RNA, Small Interfering; D000077022:Survivin; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D000069286:Bortezomib; D051794:Von Hippel-Lindau Tumor Suppressor Protein; C497446:VHL protein, human