Id-1, a Protein Repressed by miR-29b, Facilitates the TGF�1-Induced Epithelial-Mesenchymal Transition in Human Ovarian Cancer Cells

Abstract

Background: Transforming growth factor beta 1 (TGFβ1) can induce epithelial-mesenchymal transition (EMT) in various human cancers, but the complex mechanisms underlying this have not been fully elucidated. Inhibitor of DNA binding 1 (Id-1) has been identified as a novel marker of ovarian cancer progression. This study aims to investigate the role of Id-1 in TGFβ1-induced EMT in human ovarian cancer cells. Methods: Ovarian cancer cells expressing or not expressing Id-1 were incubated with TGFβ1. Changes in the EMT markers E-cadherin, vimentin, N-cadherin, Id-1, and miR-29b were detected using western blotting and qPCR analyses. Wound healing, transwell migration, and invasion assays were performed in cells where Id-1 was either knocked down or overexpressed. The effects of transfecting miR-29b mimics and inhibitors on Id-1 mRNA and protein expression were assessed. The interaction between miR-29b and Id-1 was confirmed using a luciferase reporter assay. Results: Id-1 expression was increased and miR-29b expression was repressed in TGFβ1-responsive ovarian cancer cells. Id-1 overexpression increases and Id-1 knockdown decreases cell migration and invasion capacities. Id-1 silencing leads to a partial blocking of TGFβ1-induced EMT. miR-29b negatively regulates Id-1 expression. Direct binding of miR-29b to the 3'UTR region of Id-1 was confirmed using a luciferase reporter assay. Conclusion: Id-1, a protein repressed by miR-29b, facilitates TGFβ1-induced EMT in human ovarian cancer cells and represents a promising therapeutic target for treating ovarian cancer.

A Double-Negative Feedback Interaction between MicroRNA-29b and DNMT3A/3B Contributes to Ovarian Cancer Progression

“…In our previous study, we have revealed miR-29b's direct targeting and negative regulation of Id-1 and Id-1's role in EOC progression [28]. Here, we further revealed the mutual interaction between DNMT3A and Id-1, thus confirming that the miR-29b-DNMT3A/3B-Id-1 axis regulates the activity of aberrant methylation patterns, and epigenetic alterations may be early events in the malignant transformation of cells.…”

“…4B). Similarly, we have also demonstrated the role of miR-29b and Id-1 in manipulating EOC growth and motility in early studies [19,28]. Collectively, these results reveal a mutual interaction among miR-29b, DNMT3a/3B and Id-1 that promotes the progression of EOC (Fig.…”

Co-Activation of TGFβ and Wnt Signalling Pathways Abrogates EMT in Ovarian Cancer Cells

“…TGFβ and Wnt, the master regulators of embryogenesis, are also known to induce the same functions [29, 33], being upregulated in ovarian cancer [16, 17, 32]. Crosstalk between the two pathways is reported during developmental stages [11, 12, 27], however, in cancer, though their interaction has been reported [13], the exact effect on cancer progression is still not known.…”

“…TGFβ1, with the help of different mediators [16, 17], is a known inducer of EMT, a de-differentiating process in which the epithelial cells lose their cobblestone-shaped morphology and gains spindle-shaped mesenchymal morphology with formation of actin stress fibres, reduced cell-cell junctions, polarization disruption and increased cellular motility [18, 19]. Several other signalling pathways are also known to induce EMT [9, 20, 21], Wnt signalling being one of them.…”

microRNA-29b: an Emerging Player in Human Cancer

“…GATA3 induces the expression of miR-29b, which in turn represses a network of prometastatic microenvironmental components, including ANGPTL4, LOX, MMP9 and VEGF-A (Melo and Kalluri, 2013), suggesting GATA3-miR-29b regulatory axis can inhibiting tumor invasion and metastasis. Consistently, miR-29b can lead to a partial blocking of TGFβ1-induced EMT by repressing inhibitor of DNA binding 1 (Id-1), a novel marker of ovarian cancer progression (Teng et al, 2014).…”