7048

TGFBR2

Previous studies in our laboratory identified that 3-deazaneplanocin A (DZNep), a carbocyclic adenosine analog and histone methyl transferase inhibitor, suppresses TGFbeta-induced epithelial-to-mesenchymal (EMT) characteristics. In addition, DZNep epigenetically reprograms miRNAs to regulate endogenous TGFbeta1 levels via miR-663/4787-mediated RNA interference (Mol cancer Res. 2016 Sep 13. pii: molcanres.0083.2016) (1). Although DZNep also attenuates exogenous TGFbeta-induced EMT response, the mechanism of this inhibition was unclear. Here, DZNep induced miR-202-5p to target both TGFbeta receptors, TGFBR1 and TGFBR2, for RNA interference and thereby contributes to the suppression of exogenous TGFbeta-induced EMT in pancreatic cancer cells. Lentiviral overexpression of miR-202 significantly reduced the protein levels of both TGFbeta receptors and suppressed TGFbeta signaling and EMT phenotypic characteristics of cultured parenchymal pancreatic cancer cells. Consistently, transfection of anti-miRNAs against miR-202-5p resulted in increased TGFBR1 and TGFBR2 protein expressions and induced EMT characteristics in these cells. In stellate pancreatic cells, miR-202 overexpression slowed growth as well as reduced stromal extracellular membrane matrix protein expression. In orthotopic pancreatic cancer mouse models, both immunodeficient and immunocompetent, miR-202 reduced tumor burden and metastasis. Together, these findings demonstrate an alternative mechanism of DZNep in suppressing TGFbeta signaling at the receptor level and uncover the EMT-suppressing role of miR-202 in pancreatic cancer.Implications: These findings support the possibility of combining small molecule-based (e.g., DZNep analogs) or large molecule-based (e.g., miRNAs) epigenetic modifiers with conventional nucleoside analogs (e.g., gemcitabine, capecitabine) to improve the antimetastatic potential of current pancreatic cancer therapy. Mol cancer Res; 15(8); 1029-39. (c)2017 AACR.CI - (c)2017 American Association for cancer Research.

BACKGROUND: Proteotoxic stress and transforming growth factor (TGFbeta)- induced epithelial-mesenchymal transition (EMT) are two main contributors of intraocular fibrotic disorders, including proliferative vitreoretinopathy (PVR) and proliferative diabetic retinopathy (PDR). However, how these two factors communicate with each other is not well-characterized. OBJECTIVE: The aim was to investigate the regulatory role of proteotoxic stress on TGFbeta signaling in retinal pigment epithelium. METHODS: ARPE-19 cells and primary human retinal pigment epithelial (RPE) cells were treated with proteasome inhibitor MG132 and TGFbeta. Cell proliferation was analyzed by CCK-8 assay. The levels of mesenchymal markers alpha-SMA, fibronectin, and vimentin were analyzed by real-time polymerase chain reaction (PCR), western blot, and immunofluorescence. Cell migration was analyzed by scratch wound assay. The levels of p-Smad2, total Smad2, p-extracellular signal-regulated kinase 1/2 (ERK1/2), total ERK1/2, p-focal adhesion kinase (FAK), and total FAK were analyzed by western blot. The mRNA and protein levels of TGFbeta receptor-II (TGFbetaR-II) were measured by realtime PCR and western blot, respectively. RESULTS: MG132-induced proteotoxic stress resulted in reduced cell proliferation. MG132 significantly suppressed TGFbeta-induced upregulation of alpha-SMA, fibronectin, and vimentin, as well as TGFbeta-induced cell migration. The phosphorylation levels of Smad2, ERK1/2, and FAK were also suppressed by MG132. Additionally, the mRNA level and protein level of TGFbetaR-II decreased upon MG132 treatment. CONCLUSION: Proteotoxic stress suppressed TGFbeta-induced EMT through downregulation of TGFbetaR-II and subsequent blockade of Smad2, ERK1/2, and FAK activation.CI - Copyright(c) Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Messenchymal to epithelial transition (MET) is a significant physiological phenomenon involved in embryogenesis and cancer. This study aims at investigating the mechanism of microRNA-20a (miR-20a) mediated regulation of mesenchymal to epithelial transition and identification of its direct target genes in breast cancer cell-line, MDA-MB-231. Reduced migratory and invasive property, altered cellular morphology along with reduced capability for attachment to basement membrane was acquired by over-expression of miR-20a in invasive MDA-MB-231 cell-line initially expressing low level of this micro-RNA, indicating direct correlation between abundance of miR-20a and metastatic property. The switch from mesenchymal to epithelial cells mediated by miR-20a involved post-transcriptional down-regulation of twist1, which in turn controls downstream epithelial markers like E-cadherin, claudin and mesenchymal markers like N-cadherin, fibronectin, the crucial players of mesenchymal to epithelial transition (MET). Furthermore, another key component, TGF-beta and one of its receptors (TGFBR2) were found to be down-regulated by miR-20a. Additionally, reporter assay established that post-transcriptional down-regulation of TGFBR2 occurred through direct binding of miR-20a to its 3'UTR, thus abrogating the TGF-beta signaling pathway resulting in inhibition of MET. Delineating the underlying molecular mechanism of miR-20a-mediated MET and defining the target genes will help us to introduce a miRNA-mediated effective therapeutic strategy against breast cancer.CI - Copyright (c) 2017 Elsevier Inc. All rights reserved.

epithelial-mesenchymal transition (EMT) is a conserved cellular plasticity program that is reactivated in carcinoma cells and drives metastasis. Although EMT is well studied its regulatory mechanisms remain unclear. Therefore, to identify novel regulators of EMT, a data mining approach was taken using published microarray data and a group of deubiquitinases (DUB) were found to be upregulated in cells that have undergone EMT. Here, it is demonstrated that one DUB, ubiquitin-specific peptidase 11 (USP11), enhances TGFbeta-induced EMT and self-renewal in immortalized human mammary epithelial cells. Furthermore, modulating USP11 expression in human breast cancer cells altered the migratory capacity in vitro and metastasis in vivo Moreover, elevated USP11 expression in human breast cancer patient clinical specimens correlated with decreased survival. Mechanistically, modulating USP11 expression altered the stability of TGFbeta receptor type II (TGFBR2) and TGFbeta downstream signaling in human breast cancer cells. Together, these data suggest that deubiquitination of TGFBR2 by USP11 effectively spares TGFBR2 from proteasomal degradation to promote EMT and metastasis.Implications: USP11 regulates TGFbeta-induced epithelial-mesenchymal plasticity and human breast cancer metastasis and may be a potential therapeutic target for breast cancer. Mol cancer Res; 16(7); 1172-84. (c)2018 AACR.CI - (c)2018 American Association for cancer Research.