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BMP4

In our study, we found that bone morphogenetic protein 4 (BMP4) has a novel effect as an inducer of epithelial-mesenchymal transition (EMT) on Panc-1 cells, a human pancreatic carcinoma cell line. BMP4-treated Panc-1 cells showed loose cell contacts and a scattered, fibroblast-like appearance along with E-cadherin downregulation, Vimentin upregulation and enhanced cell migration, which are characteristic of EMT. BMP4 treatment also induced homeobox gene MSX2 expression, which we previously showed to be associated with EMT in pancreatic carcinoma cells. BMP4 treatment activated the Smad signaling pathway, and extracellular signal-related kinase (ERK) and p38 mitogen-activated kinase (MAPK) pathways in these cells. MSX2 was markedly induced by BMP4 through the ERK and p38 MAPK pathways in collaboration with the Smad signaling pathway. The repression of E-cadherin, induction of Vimentin and enhanced cell migration disappeared when siRNA-based MSX2 downregulated pancreatic cancer cells were treated with BMP4. These findings indicate that BMP4 may be involved in pancreatic carcinoma development through the promotion of EMT and that MSX2 is indispensable to this process.CI - 2007 Wiley-Liss, Inc.

Proliferative vitreoretinopathy (PVR), a serious vision-threatening complication of retinal detachment (RD), is characterized by the formation of contractile fibrotic membranes, in which epithelial-mesenchymal transition (EMT) of the retinal pigment epithelium (RPE) is a major event. Recent studies suggest an important role of bone morphogenetic protein 4 (BMP4) in the suppression of fibrosis. In this study, we aimed to investigate the role of BMP4 in the pathological process of PVR, particularly in the EMT of RPE cells. We found that BMP4 and its receptors were co-labelled with cytokeratin and alpha-SMA positive cells within the PVR membrane. Moreover, the mRNA and protein expression levels of BMP4 were decreased whereas BMP4 receptors ALK2, ALK3 and ALK6 were increased during TGF-beta-induced EMT in primary RPE cells. Exogenous BMP4 inhibited TGF-beta-induced epithelial marker down-regulation, as well as mesenchymal marker up-regulation at both the mRNA and protein levels in RPE cells. In addition, BMP4 treatment attenuated the TGF-beta-induced gel contraction, cell migration and Smad2/3 phosphorylation. However, knockdown of endogenous BMP4 stimulated changes in EMT markers. Our results confirm the hypothesis that BMP4 might inhibit TGF-beta-mediated EMT in RPE cells via the Smad2/3 pathway and suppress contraction. This might represent a potential treatment for PVR.

BACKGROUND: Bone morphogenetic protein-4 (BMP4) is a key regulator of epithelial-mesenchymal transition (EMT), which is crucial for cancer cells to acquire chemoresistance. The effects of BMP4 on OXA sensitivity in HCC need to be elucidated. METHODS: Functional analysis of BMP4 on EMT-regulated OXA sensitivity was performed in human HCC specimens, in the HCC cell lines HepG2 and HCCLM3, and in a subcutaneous tumor model receiving OXA treatment. The downstream signaling targets of BMP4 in HCC were profiled and confirmed. RESULTS: BMP4 expression was significantly increased in HCC tissue, and was correlated with tumor de-differentiation and unfavorable prognosis. BMP4 promoted HCC EMT and was correlated with OXA resistance. Blocking of BMP4 reversed EMT and increased OXA chemosensitivity in vitro and in vivo. ELK1, a transcription factor involved in EMT, was an important mediator of BMP4-induced OXA resistance in HCC. Blocking of MEK/ERK/ELK1 attenuated BMP4-induced EMT and enhanced OXA sensitivity. CONCLUSIONS: BMP4 induces EMT and OXA chemoresistance via MEK/ERK/ELK1 signaling pathway in HCC. BMP4 may be a valuable therapeutic target for HCC patients receiving OXA-based chemotherapy.CI - Copyright (c) 2017 Elsevier B.V. All rights reserved.

Lung cancer is the leading cause of cancer-related death throughout the world. We aimed to investigate the role of a novel microRNA-876-5p and its potential molecular target bone morphogenetic protein 4 (BMP-4), in the epithelial-mesenchymal transition (EMT) of lung cancer. expressions of microRNA-876-5p and its potential target BMP-4 were analysed in lung cancer cells and patient tissues. Luciferase activity assay was conducted to verify direct targeting of microRNA- 876-5p to the 3'-UTR of BMP-4 mRNA. Migration, invasion capacities of lung cancer cells expressing microRNA-876-5p were analysed, and characteristics of lung cancer EMT protein markers were also evaluated. A xenograft tumour mouse model was established to address the roles of microRNA-876-5p and BMP-4 in lung cancer EMT in vivo. MicroRNA-876- 5p was decreased while BMP-4 was increased in lung cancer cells and tissues. MicroRNA-876-5p directly targeted 3'-UTR of BMP-4 mRNA to inhibit its expression. MicroRNA-876-5p expression significantly inhibited the migration, invasion and EMT of lung cancer cells in vitro, as well as metastasis in vivo, which required BMP-4 expression. MicroRNA-876-5p suppresses EMT of lung cancer by directly down-regulating BMP-4, both of which could serve as potential therapeutic targets in the treatment of lung cancer.

Our study aimed to investigate the roles and possible regulatory mechanism of miR-1277 in the development of hepatocellular carcinoma (HCC). HCC patients were identified from patients who were diagnosed with focal liver lesions using magnetic resonance imaging (MRI). The expression levels of miR-1277 in the serum of HCC patients and HepG2 cells were measured. Then miR-1277 mimic, miR-1277 inhibitor, or scramble RNA was transfected into HepG2 cells. The effects of miR-1277 overexpression and suppression on HepG2 cell proliferation, migration, and invasion were then investigated. Additionally, the expression levels of epithelial-mesenchymal transition (EMT)-related markers, including E-cadherin, beta-catenin, and vimentin, were detected. Target prediction and luciferase reporter assay were performed to explore the potential target of miR-1277. miR-1277 was significantly downregulated in the serum of HCC patients and HepG2 cells. Suppression of miR-1277 promoted HepG2 cell proliferation, migration, and invasion, whereas overexpression of miR-1277 had opposite effects. In addition, after miR-1277 was suppressed, the expressions of E-cadherin and beta-catenin were significantly increased, while the expressions of vimentin were markedly decreased. Bone morphogenetic protein 4 (BMP4) was identified as the direct target of miR-1277. Knockdown of BMP4 reversed the effects of miR-1277 suppression on HepG2 cell migration and invasion, as well as the expressions of E-cadherin, beta-catenin, and vimentin. Our results indicate that downregulation of miR-1277 may promote the migration and invasion of HepG2 cells by targeting BMP4 to induce EMT. Combination of MRI and miR-1277 level will facilitate the diagnosis and treatment of HCC.

The generation of induced pluripotent stem cells (iPSCs) by somatic cell reprogramming holds great potential for modeling human diseases. However, the reprogramming process remains very inefficient and a better understanding of its basic biology is required. The mesenchymal-to-epithelial transition (MET) has been recognized as a crucial step for the successful reprogramming of fibroblasts into iPSCs. It has been reported that the p53 tumor suppressor gene acts as a barrier of this process, while its homolog p63 acts as an enabling factor. In this regard, the information concerning the role of the third homolog, p73, during cell reprogramming is limited. Here, we derive total Trp73 knockout mouse embryonic fibroblasts, with or without Trp53, and examine their reprogramming capacity. We show that p73 is required for effective reprogramming by the Yamanaka factors, even in the absence of p53. Lack of p73 affects the early stages of reprogramming, impairing the MET and resulting in altered maturation and stabilization phases. Accordingly, the obtained p73-deficient iPSCs have a defective epithelial phenotype and alterations in the expression of pluripotency markers. We demonstrate that p73 deficiency impairs the MET, at least in part, by hindering BMP pathway activation. We report that p73 is a positive modulator of the BMP circuit, enhancing its activation by DNp73 repression of the Smad6 promoter. Collectively, these findings provide mechanistic insight into the MET process, proposing p73 as an enhancer of MET during cellular reprogramming.

CDK8 is a transcription-regulating kinase that controls TGF-beta/BMP-responsive SMAD transcriptional activation and turnover through YAP1 recruitment. However, how the CDK8/YAP1 pathway influences SMAD1 response in cancer remains unclear. Here we report that SMAD1-driven epithelial-to-mesenchymal transition (EMT) is critically dependent on matrix rigidity and YAP1 in a wide spectrum of cancer models. We find that both genetic and pharmacological inhibition of CDK8 and its homologous twin kinase CDK19 leads to abrogation of BMP-induced EMT. Notably, selectively blocking CDK8/19 specifically abrogates tumor cell invasion, changes in EMT-associated transcription factors, E-cadherin expression and YAP nuclear localization both in vitro and in vivo in a murine syngeneic EMT model. Furthermore, RNA-seq meta-analysis reveals a direct correlation between CDK8 and EMT-associated transcription factors in patients. Our findings demonstrate that CDK8, an emerging therapeutic target, coordinates growth factor and mechanical cues during EMT and invasion.