A novel TGF-β-responsive enhancer regulates SRC expression and epithelial–mesenchymal transition-associated cell migration

Abstract

The non-receptor tyrosine kinase SRC is overexpressed and/or hyperactivated in various human cancers, and facilitates cancer progression by promoting invasion and metastasis. However, the mechanisms underlying SRC upregulation are poorly understood. In this study, we demonstrated that transforming growth factor-β (TGF-β) induces SRC expression at the transcriptional level by activating a novel intragenic SRC enhancer. In the human breast epithelial cell line MCF10A and triple-negative breast cancer cell line BT-549, TGF-β1 stimulation upregulated theSRC1Apromoter, resulting in increased SRC mRNA and protein levels. Chromatin immunoprecipitation (ChIP)-sequencing analysis revealed that SMAD2 binds to three enhancer regions ~15 kb upstream and downstream of theSRCpromoter, and one of them is capable of activating theSRCpromoter in response to TGF-β. In addition, JUN, which is a member of the activator protein (AP)-1 family, also localizes to the enhancer and regulates TGF-β-induced SRC expression. Moreover, the total amount of active SRC increased, coinciding with the TGF-β-induced SRC expression. In TGF-β-induced epithelial-mesenchymal transition (EMT), TGF-β-induced SRC upregulation plays a crucial role in EMT-associated cell migration by activating the SRC/focal adhesion kinase (FAK) circuit. Overall, these results suggest that TGF-β-induced SRC upregulation promotes cancer cell invasion and metastasis in a subset of human malignancies.

KMT2A facilitates the epithelial-to-mesenchymal transition and the progression of ovarian cancer

“…3.7 KMT2A silencing reversed the TGF-β-induced EMT of ovarian cancer TGF-β is a major inducer in EMT process and tumor cell progression [10,13]. TGF-β-induced EMT is accompanied by the acquisition of mesenchymal markers such as Vimentin, and the loss of epithelial surface markers, notable as E-cadherin [10]. Here, we treated SKOV3 and HO-8910 cells with either control siRNA or KMT2A speci c siRNA, then we stimulated the cells with or without 10ng/ml TGF-β1 for 72h, we found that KMT2A expression was increased after treatment with TGF-β1, but in KMT2A knockdown SKOV3 and HO-8910 cells, TGF-β had no signi cant effect on increase of KMT2A expression (Figs.…”

“…3.7 KMT2A silencing reversed the TGF-β-induced EMT of ovarian cancer TGF-β is a major inducer in EMT process and tumor cell progression [10,13]. TGF-β-induced EMT is accompanied by the acquisition of mesenchymal markers such as Vimentin, and the loss of epithelial surface markers, notable as E-cadherin [10].…”

“…EMT can be regulated or induced by several growth and differentiation factors, such as transforming growth factor-β (TGF-β), cadherin, Notch and WNT proteins [9]. Among these, most notably, TGF-β is recognized as a potent inducer of EMT during cancer progression and metastasis [10][11][12]. TGF-β signaling pathway plays a key role in tumor cell cycle arrest, apoptosis, metastasis and EMT [13].…”

Receptor-activated transcription factors and beyond: multiple modes of Smad2/3-dependent transmission of TGF-β signaling

“…Delayed-phase STAT3 phosphorylation (later than 2 h after stimulation) is dependent on Smad3 ( 12 ). c-Src transcriptionally induced by Smad signaling plays a role in the late phase of activation ( 18 ). Because many cell responses induced by TGF-β are Smad dependent, the involvement of non-Smad pathways in the regulation of cellular functions is not well understood.…”