The soluble ectodomain of fibroblast growth factor receptor-IIIc (sFGFR2c) is able to bind to fibroblast growth factor (FGF) ligands and block the activation of the FGF-signaling pathway. In this study, sFGFR2c inhibited lung fibrosis dramatically in vitro and in vivo. The upregulation of α-smooth muscle actin (α-SMA) in fibroblasts by transforming growth factor-β1 (TGF-β1) is an important step in the process of lung fibrosis, in which FGF-2, released by TGF-β1, is involved. sFGFR2c inhibited α-SMA induction by TGF-β1 via both the extracellular signal-regulated kinase 1/2 (ERK1/2) and Smad3 pathways in primary mouse lung fibroblasts and the proliferation of mouse lung fibroblasts. In a mouse model of bleomycin (BLM)-induced lung fibrosis, mice were treated with sFGFR2c from d 3 or d 10 to 31 after BLM administration. Then we used hematoxylin and eosin staining, Masson staining and immunohistochemical staining to evaluate the inhibitory effects of sFGFR2c on lung fibrosis. The treatment with sFGFR2c resulted in significant attenuation of the lung fibrosis score and collagen deposition. The expression levels of α-SMA, p-FGFRs, p-ERK1/2 and p-Smad3 in the lungs of sFGFR2c-treated mice were markedly lower. sFGFR2c may have potential for the treatment of lung fibrosis as an FGF-2 antagonist.
Abstract. The expression of estrogen receptor-α (ERα) is one of the most important diagnostic and prognostic factors of breast cancer. Recently, ERα-36 has been identified as a novel variant of ER-α. ERα-36 lacks intrinsic transcription activity and mainly mediates non-genomic estrogen signaling. Bone morphogenetic proteins (BMPs) are recognized as key factors during the control of cell fate and cancer development. However, the correlation between BMP and the ER signaling pathway remains unclear. In this study, we show that BMP2, a member of the BMP family, is a novel inducer of ERα-36 expression in breast cancer cells. As shown by western blot assays, the upregulation of ERα-36 by BMP2 was significant. In MDA-MB-231 cells which are ERα-66-negative, BMP2 was able to induce the expression of ERα-36 in a dose-dependent manner, and the RNA interference assay indicated a correlation between BMP2 and ERα-36 expression. BMP2 inhibited the growth of MCF-7 and MDA-MB-231 cells; however, the inhibitory effect was antagonized by tamoxifen, suggesting that the ER signal was involved. The growth of MDA-MB-231 cells was stimulated by 17-β-estradiol (E2) after BMP2 induction, even though the cells were previously insensitive to E2. These results suggest that BMP2 induces ERα-36 expression and alters tumor resistance to endocrine therapy by changing the expression profile of ERs.
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