The von Hippel-Lindau tumor suppressor gene protects cells from UV-mediated apoptosis.
The familial cancer syndrome, von Hippel-Lindau (VHL) disease, characterized by a predisposition to renal cell carcinoma and certain other tumor types, is caused by mutational inactivation of the VHL tumor suppressor gene. Loss of VHL gene function is detected also in the vast majority of sporadic renal cell carcinomas. Previous reports have determined a protective role for VHL in response to serum withdrawal and glucose deprivation. In this study, the effect of UV irradiation on VHL-negative and VHL-positive renal carcinoma cells was examined. VHL-negative 786-O renal carcinoma cells underwent apoptosis following UV irradiation. In contrast, reintroduction of wild-type VHL expression protected 786-O cells from UV-mediated cell death. p53 and Bax levels were equivalent in VHL-negative and VHL-positive 786-O cells. Strikingly, cyclin-dependent kinase inhibitors p21 and p27 underwent proteasome-dependent degradation in VHL-negative 786-O cells following UV treatment. However, p21 and p27 protein levels were stable in VHL-positive cells. Also, levels of the anti-apoptotic proteins, Bcl-2 and Bcl-xL were elevated in VHL-positive cells, consistent with the protection from apoptotic stimuli. UV treatment led to increased S phase in VHL-negative, but not VHL-positive cells. Thus, following UV irradiation, diminution of p21 and p27 levels resulted in a hyperproliferative state in VHL-negative cells, leading to apoptosis. These results suggest that loss of VHL function promotes apoptosis and may provide selective pressure toward cells that are able to escape apoptosis, leading to tumorigenesis.
Schoenfeld
A R
AR
Department of Microbiology and Immunology, Marion Bessin Liver Research Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Parris
T
T
Eisenberger
A
A
Davidowitz
E J
EJ
De Leon
M
M
Talasazan
F
F
Devarajan
P
P
Burk
R D
RD
D017209:Apoptosis / Q000235:genetics / Q000528:radiation effects*; D002292:Carcinoma, Renal Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D015972:Gene Expression Regulation, Neoplastic; D016147:Genes, Tumor Suppressor / Q000502:physiology*; D016158:Genes, p53 / Q000235:genetics; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008025:Ligases; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D011506:Proteins / Q000235:genetics* / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D016196:S Phase / Q000528:radiation effects; D014407:Tumor Cells, Cultured / Q000528:radiation effects; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D014466:Ultraviolet Rays; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D051020:bcl-X Protein
C494811:BCL2L1 protein, human; C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D008869:Microtubule-Associated Proteins; D011506:Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D025521:Tumor Suppressor Proteins; D051020:bcl-X Protein; D050760:Cyclin-Dependent Kinase Inhibitor p27; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D008025:Ligases; C497446:VHL protein, human