WT1 modulates apoptosis by transcriptionally upregulating the bcl-2 proto-oncogene.
The Wilms' tumor suppressor gene, WT1, encodes a zinc finger transcription factor that has been demonstrated to negatively regulate several growth factor and cognate receptor genes. However, inconsistent with its tumor suppressor function, WT1 has also been demonstrated to be required to inhibit programmed cell death in vitro and in vivo. Moreover, anaplastic Wilms' tumors, which typically express wild-type WT1, display extreme resistance to chemotherapeutic agents that kill tumor cells through the induction of apoptosis. Although p53 mutations in anaplastic Wilms' tumors have been associated with chemoresistance, this event is believed to occur late during tumor progression. Therefore, since dysregulated WT1 expression occurs relatively early in Wilms' tumors, we hypothesized that WT1 was required to transcriptionally upregulate genes that provide a cell survival advantage to tumor cells. Here we demonstrate that sporadic Wilms' tumors coexpress WT1 and the anti-apoptotic Bcl-2 protein. Using rhabdoid cell lines overexpressing WT1, we show that WT1 activates the endogenous bcl-2 gene through a transcriptional mechanism. Transient transfections and electromobility shift assays demonstrate that WT1 positively stimulates the bcl-2 promoter through a direct interaction. Moreover, WT1 expressing cells displaying upregulated Bcl-2 were found to be resistant to apoptosis induced by staurosporine, vincristine and doxorubicine. These data suggest that in certain cellular contexts, WT1 exhibits oncogenic potential through the transcriptional upregulation of anti-apoptotic genes such as bcl-2.
Lineberger Comprehensive Cancer Center, School of Dentistry, University of North Carolina, Chapel Hill, NC 27599-7295, USA.
M W
MW
Mayo
C Y
CY
Wang
S S
SS
Drouin
L V
LV
Madrid
A F
AF
Marshall
J C
JC
Reed
B E
BE
Weissman
A S
AS
Baldwin
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D016384:Consensus Sequence / Q000235:genetics; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D004317:Doxorubicin / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D019254:Genes, bcl-2 / Q000235:genetics*; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D000090063:Proto-Oncogene Mas; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D019311:Staurosporine / Q000494:pharmacology; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured; D014750:Vincristine / Q000494:pharmacology; D025721:WT1 Proteins; D009396:Wilms Tumor / Q000235:genetics / Q000378:metabolism
D004268:DNA-Binding Proteins; C000715470:MAS1 protein, human; D020033:Protein Isoforms; D000090063:Proto-Oncogene Mas; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D014157:Transcription Factors; D025721:WT1 Proteins; D014750:Vincristine; D004317:Doxorubicin; D004247:DNA; D019311:Staurosporine