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Epigenetic downregulation of human disabled homolog 2 switches TGF-beta from a tumor suppressor to a tumor promoter.

ABSTRACT: The cytokine TGF-beta acts as a tumor suppressor in normal epithelial cells and during the early stages of tumorigenesis. During malignant progression, cancer cells can switch their response to TGF-beta and use this cytokine as a potent oncogenic factor; however, the mechanistic basis for this is poorly understood. Here we demonstrate that downregulation of disabled homolog 2 (DAB2) gene expression via promoter methylation frequently occurs in human squamous cell carcinomas (SCCs) and acts as an independent predictor of metastasis and poor prognosis. Retrospective microarray analysis in an independent data set indicated that low levels of DAB2 and high levels of TGFB2 expression correlate with poor prognosis. Immunohistochemistry, reexpression, genetic knockout, and RNAi silencing studies demonstrated that downregulation of DAB2 expression modulated the TGF-beta/Smad pathway. Simultaneously, DAB2 downregulation abrogated TGF-beta tumor suppressor function, while enabling TGF-beta tumor-promoting activities. Downregulation of DAB2 blocked TGF-beta-mediated inhibition of cell proliferation and migration and enabled TGF-beta to promote cell motility, anchorage-independent growth, and tumor growth in vivo. Our data indicate that DAB2 acts as a tumor suppressor by dictating tumor cell TGF-beta responses, identify a biomarker for SCC progression, and suggest a means to stratify patients with advanced SCC who may benefit clinically from anti-TGF-beta therapies.

SUBMITTER: Hannigan A

PROVIDER: S-EPMC2912175 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature

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Epigenetic downregulation of human disabled homolog 2 switches TGF-beta from a tumor suppressor to a tumor promoter.

Hannigan Adèle A Smith Paul P Kalna Gabriela G Lo Nigro Cristiana C Orange Clare C O'Brien Darren I DI Shah Reshma R Syed Nelofer N Spender Lindsay C LC Herrera Blanca B Thurlow Johanna K JK Lattanzio Laura L Monteverde Martino M Maurer Meghan E ME Buffa Francesca M FM Mann Jelena J Chu David C K DC West Catharine M L CM Patridge Max M Oien Karin A KA Cooper Jonathan A JA Frame Margaret C MC Harris Adrian L AL Hiller Louise L Nicholson Linda J LJ Gasco Milena M Crook Tim T Inman Gareth J GJ

The Journal of clinical investigation 20100701 8

The cytokine TGF-beta acts as a tumor suppressor in normal epithelial cells and during the early stages of tumorigenesis. During malignant progression, cancer cells can switch their response to TGF-beta and use this cytokine as a potent oncogenic factor; however, the mechanistic basis for this is poorly understood. Here we demonstrate that downregulation of disabled homolog 2 (DAB2) gene expression via promoter methylation frequently occurs in human squamous cell carcinomas (SCCs) and acts as an ...[more]

PMID: 20592473

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Project description:BACKGROUND & AIMS: Pancreatic ductal adenocarcinoma (PDAC) is usually incurable. Contrary to genetic mechanisms involved in PDAC pathogenesis, epigenetic alterations are ill defined. Here we determine the contribution of epigenetically silenced genes to the development of PDAC. METHODS: We investigated methylated DNAs from PDACs, chronic pancreatitis and normal pancreatic tissues using Methyl-CpG immunoprecipitation followed by microarray hybridization. Promoter methylation of selected genes was confirmed with the Epityper assay. Expression levels were evaluated by quantitative RT-PCR. WNK2 was further investigated in tissue microarrays, methylation analysis of early pancreatic intraepithelial neoplasia (PanINs), mouse models for PDAC and pancreatitis, re-expression studies after demethylation, and cell growth assays using WNK2 overexpression. RESULTS: A total of 3.8% of 27.800 interrogated CpG islands were hypermethylated in PDAC versus normal and chronic pancreatitis tissues. Hypermethylation was confirmed in 12 out of 13 selected islands and was associated with gene silencing in 4 of them. The most prominently hypermethylated gene, WNK2, was further investigated. Demethylation assays confirmed the link between methylation and expression. WNK2 hypermethylation was higher in pancreatic tumor cells than in surrounding inflamed tissues and was observed in PanIN lesions as well as in a PDAC mouse model. WNK2 mRNA and protein expression were lower in PDAC and chronic pancreatitis compared to normal tissues both in patients and mouse models. Overexpression of WNK2 led to a reduced cell growth and WNK2 expression in tissues correlated negatively with the expression of pERK1/2, a downstream target of WNK2 responsible for cell proliferation. CONCLUSIONS: WNK2 is downregulated by promoter hypermethylation early in PDAC pathogenesis and may support tumor cell growth via the ERK-MAPK pathway. 3 types of pancreatic tissue samples: 5 normals, 2 chronic pancreatitis, 7 tumors (PDAC)

Dataset Information

Epigenetic downregulation of human disabled homolog 2 switches TGF-beta from a tumor suppressor to a tumor promoter.

Publications

Epigenetic downregulation of human disabled homolog 2 switches TGF-beta from a tumor suppressor to a tumor promoter.

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