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Transforming growth factor beta1 enhances tumor promotion in mouse skin carcinogenesis.

ABSTRACT: Transforming growth factor beta1 (TGFbeta1) expression is elevated by tumor promoters in the mouse skin, but its role in tumor promotion has not been well defined. To investigate this, we have compared TGFbeta1+/+ and +/- mice in a two-stage skin chemical carcinogenesis protocol. Surprisingly, TGFbeta1+/- mice had fewer number and incidence of benign papillomas, reduced epidermal and tumor cell proliferation and reduced epidermal TGFbeta1 and nuclear p-Smad2 localization in response to the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA) compared with TGFbeta1+/+ mice. Maximal TPA activation of protein kinase C (PKCalpha) as measured by activity assays and activation of target genes and induction of cornified envelopes correlated with TGFbeta1 gene dosage in keratinocytes and addition of exogenous TGFbeta1 restored the cornification defect in TGFbeta1+/- keratinocytes. Similarly, inhibition of ALK5-suppressed TPA-mediated PKCalpha activation suggesting that physiological levels of TGFbeta1 are required for maximal activation of PKC-dependent mitogenic responses. Paradoxically, the TPA-induced inflammatory response was greater in TGFbeta1+/- skin, but TGFbeta1+/+ papillomas had more tumor infiltrating myeloperoxidase-positive cells and pro-inflammatory gene expression was elevated in v-ras(Ha)-transduced TGFbeta1+/+ but not TGFbeta1+/- keratinocytes. Thus, ras activation switches TGFbeta1 to a pro-inflammatory cytokine. Despite this differential proliferative and inflammatory response to TPA and enhanced papilloma formation in the TGFbeta1+/+ mice, the frequency of malignant conversion was reduced compared with TGFbeta1+/- mice. Therefore, TGFbeta1 promotes benign tumors by modifying tumor promoter-induced cell proliferation and inflammation but retains a suppressive function for malignant conversion.

SUBMITTER: Perez-Lorenzo R

PROVIDER: S-EPMC2878359 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature

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Transforming growth factor beta1 enhances tumor promotion in mouse skin carcinogenesis.

Pérez-Lorenzo Rolando R Markell Lauren Mordasky LM Hogan Kelly A KA Yuspa Stuart H SH Glick Adam B AB

Carcinogenesis 20100219 6

Transforming growth factor beta1 (TGFbeta1) expression is elevated by tumor promoters in the mouse skin, but its role in tumor promotion has not been well defined. To investigate this, we have compared TGFbeta1+/+ and +/- mice in a two-stage skin chemical carcinogenesis protocol. Surprisingly, TGFbeta1+/- mice had fewer number and incidence of benign papillomas, reduced epidermal and tumor cell proliferation and reduced epidermal TGFbeta1 and nuclear p-Smad2 localization in response to the tumor ...[more]

PMID: 20172950

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Project description:BACKGROUND:Functional antagonism between transforming growth factor beta (TGF-beta) and hyaluronidase has been demonstrated. For example, testicular hyaluronidase PH-20 counteracts TGF-beta1-mediated growth inhibition of epithelial cells. PH-20 sensitizes various cancer cells to tumor necrosis factor (TNF) cytotoxicity by upregulating proapoptotic p53 and WW domain-containing oxidoreductase (WOX1). TGF-beta1 blocks PH-20-increased TNF cytotoxicity. In the present study, the functional antagonism between TGF-beta1 and lysosomal hyaluronidases Hyal-1 and Hyal-2 was examined. RESULTS:Murine L929 fibroblasts were engineered to stably express green-fluorescent protein (GFP)-tagged hyaluronidase (GFP-Hyal-1 or GFP-Hyal-2) or GFP alone. Compared to control cells, Hyal-2-expressing cells had a significantly increased sensitivity to TNF cytotoxicity (approximately 60-110% increase), while Hyal-1-expressing cells were less sensitive to TNF (approximately 20-90% increase). TNF activated NF-kappaB, along with IkappaBalpha degradation, occurred at 20 to 60 min in Hyal-2 cells post stimulation, but at the 20 min time point in both control and Hyal-1 cells. Hyal-2 cells, but not Hyal-1 and control cells, constitutively expressed WOX1, and transiently expressed Hyal-2 enhanced WOX1-mediated cell death. Unlike PH-20, Hyal-1 and Hyal-2 did not induce p53 expression. Hyal-2 translocated from the lysosome to the mitochondria during staurosporine-mediated apoptosis, suggesting that Hyal-2 may damage mitochondria. Finally, Hyal-1 and Hyal-2 blocked TGF-beta1-enhanced L929 cell growth. In contrast, TGF-beta1 inhibited Hyal-1- and Hyal-2-increased TNF cytotoxicity in L929 cells by 30-50%. CONCLUSIONS:TGF-beta1 limits the ability of Hyal-2 to induce TNF cytotoxicity in L929 cells. Hyal-2-increased TNF cytotoxicity in L929 cells appears to be correlated with upregulation of WOX1, a prolonged NF-kappaB activation, and Hyal-2 translocation to the mitochondria during apoptosis.

Dataset Information

Transforming growth factor beta1 enhances tumor promotion in mouse skin carcinogenesis.

Publications

Transforming growth factor beta1 enhances tumor promotion in mouse skin carcinogenesis.

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