Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

MEF-mKras-WT1

ABSTRACT: K-ras is one of the most frequently mutated human oncogenes. Activation of K-ras can lead to either senescence or proliferation in primary cells. The precise mechanism governing these distinct outcomes remains unclear. Here we utilized a loss-of-function screen to assess the role of specific genes identified as potential key regulators of K-ras driven oncogenesis. Using this approach, we identify the transcription factor Wt1 as an inhibitor of senescence in primary cells expressing oncogenic K-ras. Deletion or suppression of Wt1 expression leads to senescence of primary cells expressing oncogenic K-ras under the control of the native promotor at physiological levels, but has no effect on cells expressing wild-type K-ras. Wt1 contributes to K-ras driven lung tumorigenesis in vivo and loss of Wt1 is specifically deleterious to human lung cancer cell lines that are dependent on oncogenic K-ras. Taken together, these observations reveal a novel role for Wt1 as a key regulator of the complex genetic network required for the oncogenic effect of the small GTPase K-ras. We compare the expression profiles of Wild type, K-ras mutant, Wt1-null, and double K-ras mutant/Wt1-null mouse embryonic fibroblasts (MEFs). The study provides insights into the transcriptional role of Wt1 in the context of oncogenic K-ras. MEFs were infected with adenoviral Cre to activate K-ras (6 samples), knockout Wt1 (5 samples), both activate K-ras and knockout Wt1 (7 samples). As a control, MEFs were infected with adenoviral GFP (5 samples). RNA was isolated using Trizol 7 days after infection. RNA was further prepared by passage over an RNeasy column. cDNA synthesis, biotinylation of cRNA and hybridization to mouse Genechip 430A v2 containing 39,000 probes was performed according to the manufacturer's instructions (Affymetrix, Santa Clara). Microarray data was normalized with Expression Console software (Affymetrix, Santa Clara) using RMA algorithms.

ORGANISM(S): Mus musculus

SUBMITTER: E.Alejandro Sweet-Cordero

PROVIDER: E-GEOD-15325 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Wilms tumor 1 (WT1) regulates KRAS-driven oncogenesis and senescence in mouse and human models.

Vicent Silvestre S Chen Ron R Sayles Leanne C LC Lin Chenwei C Walker Randal G RG Gillespie Anna K AK Subramanian Aravind A Hinkle Gregory G Yang Xiaoping X Saif Sakina S Root David E DE Huff Vicki V Hahn William C WC Sweet-Cordero E Alejandro EA

The Journal of clinical investigation 20101025 11

KRAS is one of the most frequently mutated human oncogenes. In some settings, oncogenic KRAS can trigger cellular senescence, whereas in others it produces hyperproliferation. Elucidating the mechanisms regulating these 2 drastically distinct outcomes would help identify novel therapeutic approaches in RAS-driven cancers. Using a combination of functional genomics and mouse genetics, we identified a role for the transcription factor Wilms tumor 1 (WT1) as a critical regulator of senescence and p ...[more]

PMID: 20972333

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Project description:The t(11;22)(p13;q12) translocation is pathognomonic for the highly aggressive desmoplastic small round cell tumour (DSRCT). The translocation fuses exon 7 of the EWS gene to exon 8 of the WT1 gene (EWS/WT1). Two splice variants of EWS/WT1 exist, arising from the presence (+KTS) or absence (-KTS) of three amino acids: lysine, threonine and serine between zinc fingers 3 and 4. To investigate the oncogenic properties of both isoforms of EWS/WT1, we over-expressed EWS/WT1 in untransformed murine embryonic fibroblasts (MEFs). We demonstrate that neither isoform of EWS/WT1 is sufficient to transform wild type MEFs, however the oncogenic potential of both isoforms is unmasked by the loss of p53. Expression of EWS/WT1 in MEFs lacking at least one allele of p53 resulted in enhanced cell proliferation, clonogenic survival and anchorage-independent growth. In addition EWS/WT1 expression in wild type MEFs attenuated several p53-dependent responses, including cell cycle arrest after irradiation and daunorubicin induced apoptosis. We show that DSRCT commonly have copy number amplification of MDM2 and MDMX, suggesting loss of p53 function in the tumours. Expression of either isoform of EWS/WT1 in MEFs induced characteristic mRNA expression profiles, including up-regulation of canonical Wnt pathway signaling. This was validated in cell lines and in a series of DSCRT, which confirmed canonical Wnt pathway activation in the tumours. We show for the first time that both isoforms of EWS/WT1 have oncogenic potential and that in addition to co-operating with loss of p53 function can also further attenuate p53-mediated responses. In addition we provide the first link between EWS/WT1 and Wnt pathway signaling. These data provide novel insights into the function of the EWS/WT1 fusion protein which characterizes DSCRT. Four independently generated pools of wild type MEFs were infected with tetracycline repressible EWS/WT1+KTS, EWS/WT1-KTS or GFP, selected with hygromycin and protein expression confirmed. Four GFP, four KTS+ and four KTS- samples were hybridized to the Ilumina BeadChip.

Dataset Information

MEF-mKras-WT1

Publications

Wilms tumor 1 (WT1) regulates KRAS-driven oncogenesis and senescence in mouse and human models.

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