Obesity, a condition characterized by increased fat content and altered secretion of adipokines, is a risk factor for postmenopausal breast cancer. Visfatin has recently been established as a novel adipokine that is highly enriched in visceral fat. Here we report that visfatin regulated proliferation of MCF-7 human breast cancer cells. Exogenous administration of recombinant visfatin increased cell proliferation and DNA synthesis rate in MCF-7 cells. Furthermore, visfatin activated G1-S phase cell cycle progression by upregulation of cyclin D1 and cdk2 expression. Visfatin also increased the expression of matrix metalloproteinases 2, matrix metalloproteinases 9, and vascular endothelial growth factor genes, suggesting that it may function in metastasis and angiogenesis of breast cancer. Taken together, these findings suggest that visfatin plays an important role in breast cancer progression.
Pleiotrophin (PTN) is a hepatocyte growth factor and considered to play roles in liver fibrogenesis and hepatocarcinogenesis. In this study we examined the mechanism of the action of PTN in these pathological processes. First, we confirmed that hepatic stellate cells (HSCs) and Kupffer cells, and also later hepatocytes in hyperplastic nodules increased PTN mRNA expressions during carbon tetrachloride-induced liver fibrosis. Then, the relationship between PTN and transforming growth factor b1 (TGFb1), a known potent pro-fibrogenetic cytokine, in carcinogenesis was investigated using hepatoma cell lines. Huh-7 human hepatoma cells weakly expressed PTN, but HepG2 human hepatoma cells and FaO rat hepatoma cells did not. Recombinant (r) TGFb1 induced the cultured Huh-7 cells to undergo apoptosis, which was inhibited by rPTN. Huh-7 cells became resistant to TGFb1-, but not mitomycin C-induced apoptosis when transfected with PTN gene, indicating the specificity of the PTN anti-apoptotic activity. Poly ADP ribose polymerase, procaspase-8 and procaspase-3 were not cleaved in the TGFb1-reluctant cells. The TGFb1-induced caspase-3 activation was also suppressed in Huh-7 and FaO cells both transduced with PTN gene-bearing adenoviruses. In summary, PTN was expressed in HSCs, Kupffer cells, and hepatocytes in fibrotic liver. We propose that PTN specifically antagonizes the TGFb1 activity during liver fibrosis. ß
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