EW‐7203, a novel small molecule inhibitor of transforming growth factor‐β (TGF‐β) type I receptor/activin receptor‐like kinase‐5, blocks TGF‐β1‐mediated epithelial‐to‐mesenchymal transition in mammary epithelial cells

Abstract

Recently, small molecule inhibitors of transforming growth factorb (TGF-b) type I receptor kinase ⁄ activin receptor-like kinase-5 (ALK5) have been developed to target TGF-b signalling as a therapeutic strategy for combating cancer. In the present study, the authors examined a novel small molecule inhibitor of ALK5,[3][4][5]2,4]triazolo [1,5-a]pyridin-6-yl)-4-(6-methylpyridin-2-yl)thiazol-2-ylamino)methyl)benzonitrile (EW-7203) in breast cancer cells to determine if it has potential for cancer treatment. The inhibitory effects of EW-7203 on TGF-b-induced Smad signalling and epithelial-to-mesenchymal transition (EMT) were investigated in mammary epithelial cells using luciferase reporter assays, immunoblotting, confocal microscopy and wound healing assays. In addition, the suppressive effects of EW-7203 on mammary cancer metastasis to the lung were examined using a Balb ⁄ c xenograft model system. The novel ALK5 inhibitor, EW-7203, inhibited the TGF-b1-stimulated transcriptional activation of p3TP-Lux and pCA-GA 12 -Luc. In addition, EW-7203 decreased phosphorylated Smad2 levels and the nuclear translocation of Smad2 was increased by TGF-b1. In addition, EW-7203 inhibited TGF-b1-induced EMT and wound healing of NMuMG cells. Furthermore, in xenografted Balb ⁄ c mice, EW-7203 inhibited metastasis to the lung from breast tumors. The novel ALK5 inhibitor, EW-7203, efficiently inhibited TGF-b1-induced Smad signalling, EMT and breast tumor metastasis to the lung in vivo, demonstrating that EW-7203 has therapeutic potential for breast cancer metastasis to the lung. (Cancer Sci 2011; 102: 1889-1896 M etastasis is the primary cause of death among cancer patients, and breast cancer patients are no exception.(1,2) During breast cancer progression, transforming growth factor-b (TGF-b) levels are elevated (3,4) and the tumor-suppressing function of TGF-b is abrogated.(5) Transforming growth factor-b has at least two roles during carcinogenesis, for although it was initially found to be a tumor-suppressing cytokine, it also acts as a mediator of metastasis to the lung.(6,7) During the initial stage of metastasis, cancer cells undergo epithelial-to-mesenchymal transition (EMT), which involves loss of epithelial cell polarity, acquisition of the mesenchymal phenotype, greater motility and invasiveness, and disruption of cell-to-cell adhesion. The EMT is generally induced in epithelial cells by signals released from mesenchymal cells that compose the stroma of normal and neoplastic tissues. Furthermore, members of the TGF-b cytokine family are the foremost characterized inducers of EMT during embryonic development, wound healing, fibrotic diseases and cancer pathogenesis, (7,9) which suggests that TGFb might induce EMT via multiple signalling mechanisms. The canonical TGF-b signalling pathway is activated when TGF-b binds to TGF-b type II receptor (TbRII). Initially, this binding facilitates activation of TGF-b type I receptor (TbRI) kinase (activin receptor-like kinase 5 [ALK5]), (10) which contains a kinase domain that phospho...

Evolution and dynamics of pancreatic cancer progression

“…35–38 The consequences of disruption of BMP signaling in pancreatic cancer metastasis, similarly inactivated by Smad4 loss, are less well studied. However, given their implications in metastasis in other tumor types 39–41 dysregulated BMP signaling likely also contributes to pancreatic cancer aggressiveness.…”

Epithelial-mesenchymal transition: focus on metastatic cascade, alternative splicing, non-coding RNAs and modulating compounds

“…Other well-known compounds are antiangiogenic drugs sorafenib and sunitinib that inhibit VEGFR and PDGFR, exhibit antifibrotic effects in the liver and have been demonstrated to inhibit EMT in in vitro cell culture models [88-90]. Compounds EW-7195 and EW-7203 target TGF-β type I receptor kinase/activin receptor like kinase-5 (ALK5) in a similar way, inhibiting TGF-β-induced EMT of mammary epithelial cells and preventing breast cancer metastasis to lung [91,92]. …”

Crosstalk of proteins, miRNAs involved in metastatic and epithelial–mesenchymal transition pathways

“…When in an experiment MCF-10A cells were exposed to fibronectin it has led to the stimulation of the migration and induction of an EMT event which includes the upregulation of the markers of EMT, for example MMP2, Vimentin, Snail, Smad2, N-cadherin, etc. (Park et al 2011) These studies are a clear indication of the major role of fibronectin in EMT through stimulating the activity of TGF-b. In addition, exogenous fibronectin is able to induce EMT under serumfree conditions; this process could be reversed following addition of a TGF-b-neutralizing antibody (Park et al 2011).…”

“…(Park et al 2011) These studies are a clear indication of the major role of fibronectin in EMT through stimulating the activity of TGF-b. In addition, exogenous fibronectin is able to induce EMT under serumfree conditions; this process could be reversed following addition of a TGF-b-neutralizing antibody (Park et al 2011). These data suggest that fibronectin can induce EMT in breast cancers by enhancing the activity of endogenous TGF-b.…”