Paracrine and epigenetic control of CAF-induced metastasis: the role of HOTAIR stimulated by TGF-ß1 secretion

Abstract

BackgroundThe communication between carcinoma associated fibroblasts (CAFs) and cancer cells facilitate tumor metastasis. In this study, we further underlying the epigenetic mechanisms of CAFs feed the cancer cells and the molecular mediators involved in these processes.MethodsMCF-7 and MDA-MB-231 cells were treated with CAFs culture conditioned medium, respectively. Cytokine antibody array, enzyme-linked immunosorbent assay, western blotting and immunofluorescence were used to identify the key chemokines. Chromatin immunoprecipitation and luciferase reporter assay were performed to explore the transactivation of target LncRNA by CAFs. A series of in vitro assays was performed with RNAi-mediated knockdown to elucidate the function of LncRNA. An orthotopic mouse model of MDA-MB-231 was conducted to confirm the mechanism in vivo.ResultsHere we reported that TGF-β1 was top one highest level of cytokine secreted by CAFs as revealed by cytokine antibody array. Paracrine TGF-β1 was essential for CAFs induced EMT and metastasis in breast cancer cells, which is a crucial mediator of the interaction between stromal and cancer cells. CAF-CM significantly enhanced the HOTAIR expression to promote EMT, whereas treatment with small-molecule inhibitors of TGF-β1 attenuated the activation of HOTAIR. Most importantly, SMAD2/3/4 directly bound the promoter site of HOTAIR, located between nucleotides -386 and -398, -440 and -452, suggesting that HOTAIR was a directly transcriptional target of SMAD2/3/4. Additionally, CAFs mediated EMT by targeting CDK5 signaling through H3K27 tri-methylation. Depletion of HOTAIR inhibited CAFs-induced tumor growth and lung metastasis in MDA-MB-231 orthotopic animal model.ConclusionsOur findings demonstrated that CAFs promoted the metastatic activity of breast cancer cells by activating the transcription of HOTAIR via TGF-β1 secretion, supporting the pursuit of the TGF-β1/HOTAIR axis as a target in breast cancer treatment.Electronic supplementary materialThe online version of this article (10.1186/s12943-018-0758-4) contains supplementary material, which is available to authorized users.

Molecular mechanisms of long noncoding RNAs‐mediated cancer metastasis

“…71 Several recent studies have reported that CAFs-secreted TGF-β promotes cancer metastasis via regulation of lncRNA expression. 72,73 CXCL14 high CAFs upregulated LINC00092, which directly binds to PFKBP2 and promotes metastasis of ovarian cancer by altering glycolysis. 74 These findings suggest that modulation of CAF-derived signals by targeting lncRNAs could serve as a novel therapeutic strategy.…”

“…Activated fibroblasts are also producers of cytokines, chemokines, metabolites, enzymes, and ECM . Several recent studies have reported that CAFs‐secreted TGF‐β promotes cancer metastasis via regulation of lncRNA expression . CXCL14 high CAFs upregulated LINC00092, which directly binds to PFKBP2 and promotes metastasis of ovarian cancer by altering glycolysis .…”

Emerging roles of long non‐coding RNA in cancer

“…In breast cancer, cancer‐associated fibroblasts (CAF) transcriptionally activate HOTAIR through the direct binding of SMAD2/3/4 to the HOTAIR promoter region. Then, HOTAIR epigenetically represses CDK5RAP1, stimulating CDK5 signaling and inducing EMT . PVT1 acts as competing endogenous RNA (ceRNA) for miR152, activating Hedgehog signaling and promoting EMT in hepatic stellate cells and thereby contributing to liver fibrosis .…”

Transcriptional regulation of normal human mammary cell heterogeneity and its perturbation in breast cancer

“…Loss of TP53 in stromal fibroblasts has also been shown to promote breast tumor development in vivo through the production of SDF-1 (Addadi et al, 2010). Additional reported mechanisms include the altered expression in CAFs of non-coding RNAs and microRNAs (Verghese et al, 2013;Shah et al, 2015;Ren et al, 2018). Other components of the tumor microenvironment, including tumor-associated macrophages, have been implicated in tumor promotion through the expression of TFEB (Fang et al, 2017).…”