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Epithelial-mesenchymal-transition-like and TGF? pathways associated with autochthonous inflammatory melanoma development in mice.

ABSTRACT: We compared gene expression signatures of aggressive amelanotic (Amela) melanomas with those of slowly growing pigmented melanomas (Mela), identifying pathways potentially responsible for the aggressive Amela phenotype. Both tumors develop in mice upon conditional deletion in melanocytes of Ink4a/Arf tumor suppressor genes with concomitant expression of oncogene H-Ras(G12V) and a known tumor antigen. We previously showed that only the aggressive Amela tumors were highly infiltrated by leukocytes concomitant with local and systemic inflammation. We report that Amela tumors present a pattern of de-differentiation with reduced expression of genes involved in pigmentation. This correlates with reduced and enhanced expression, respectively, of microphthalmia-associated (Mitf) and Pou3f2/Brn-2 transcription factors. The reduced expression of Mitf-controlled melanocyte differentiation antigens also observed in some human cutaneous melanoma has important implications for immunotherapy protocols that generally target such antigens. Induced Amela tumors also express Epithelial-Mesenchymal-Transition (EMT)-like and TGF?-pathway signatures. These are correlated with constitutive Smad3 signaling in Amela tumors and melanoma cell lines. Signatures of infiltrating leukocytes and some chemokines such as chemotactic cytokine ligand 2 (Ccl2) that contribute to leukocyte recruitment further characterize Amela tumors. Inhibition of the mitogen-activated protein kinase (MAPK) activation pathway in Amela tumor lines leads to reduced expression of EMT hallmark genes and inhibits both proinflammatory cytokine Ccl2 gene expression and Ccl2 production by the melanoma cells. These results indicate a link between EMT-like processes and alterations of immune functions, both being controlled by the MAPK pathway. They further suggest that targeting the MAPK pathway within tumor cells will impact tumor-intrinsic oncogenic properties as well as the nature of the tumor microenvironment.

SUBMITTER: Wehbe M

PROVIDER: S-EPMC3500287 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Epithelial-mesenchymal-transition-like and TGFβ pathways associated with autochthonous inflammatory melanoma development in mice.

Wehbe Maria M Soudja Saïdi M SM Mas Amandine A Chasson Lionel L Guinamard Rodolphe R de Tenbossche Céline Powis CP Verdeil Grégory G Van den Eynde Benoît B Schmitt-Verhulst Anne-Marie AM

PloS one 20121116 11

We compared gene expression signatures of aggressive amelanotic (Amela) melanomas with those of slowly growing pigmented melanomas (Mela), identifying pathways potentially responsible for the aggressive Amela phenotype. Both tumors develop in mice upon conditional deletion in melanocytes of Ink4a/Arf tumor suppressor genes with concomitant expression of oncogene H-Ras(G12V) and a known tumor antigen. We previously showed that only the aggressive Amela tumors were highly infiltrated by leukocytes ...[more]

PMID: 23173060

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Project description:BACKGROUND & AIMS:Chronic failure of mechanisms that promote effective regeneration of dead hepatocytes causes replacement of functional hepatic parenchyma with fibrous scar tissue, ultimately resulting in cirrhosis. Therefore, defining and optimizing mechanisms that orchestrate effective regeneration might prevent cirrhosis. We hypothesized that effective regeneration of injured livers requires hepatocytes to evade the growth-inhibitory actions of TGF?, since TGF? signaling inhibits mature hepatocyte growth but drives cirrhosis pathogenesis. METHODS:Wild-type mice underwent 70% partial hepatectomy (PH); TGF? expression and signaling were evaluated in intact tissue and primary hepatocytes before, during, and after the period of maximal hepatocyte proliferation that occurs from 24-72?h after PH. To determine the role of Yap1 in regulating TGF? signaling in hepatocytes, studies were repeated after selectively deleting Yap1 from hepatocytes of Yap1flox/flox mice. RESULTS:TGF? expression and hepatocyte nuclear accumulation of pSmad2 and Yap1 increased in parallel with hepatocyte proliferative activity after PH. Proliferative hepatocytes also upregulated Snai1, a pSmad2 target gene that promotes epithelial-to-mesenchymal transition (EMT), suppressed epithelial genes, induced myofibroblast markers, and produced collagen 1?1. Deleting Yap1 from hepatocytes blocked their nuclear accumulation of pSmad2 and EMT-like response, as well as their proliferation. CONCLUSION:Interactions between the TGF? and Hippo-Yap signaling pathways stimulate hepatocytes to undergo an EMT-like response that is necessary for them to grow in a TGF?-enriched microenvironment and regenerate injured livers. LAY SUMMARY:The adult liver has an extraordinary ability to regenerate after injury despite the accumulation of scar-forming factors that normally block the proliferation and reduce the survival of residual liver cells. We discovered that liver cells manage to escape these growth-inhibitory influences by transiently becoming more like fibroblasts themselves. They do this by reactivating programs that are known to drive tissue growth during fetal development and in many cancers. Understanding how the liver can control programs that are involved in scarring and cancer may help in the development of new treatments for cirrhosis and liver cancer.

Dataset Information

Epithelial-mesenchymal-transition-like and TGF? pathways associated with autochthonous inflammatory melanoma development in mice.

Publications

Epithelial-mesenchymal-transition-like and TGFβ pathways associated with autochthonous inflammatory melanoma development in mice.

Similar Datasets

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