miR-29c plays a suppressive role in breast cancer by targeting the TIMP3/STAT1/FOXO1 pathway

Abstract

BackgroundmiR-29c has been associated with the progression of many cancers. However, the function and mechanism of miR-29c have not been well investigated in breast cancers.MethodsReal-time quantitative PCR was used to assess expression of miR-29c and DNMT3B mRNA. Western blot and immunochemistry were used to examine the expression of DNA methyltransferase 3B (DNMT3B) protein in breast cancer cells and tissues. The functional roles of miR-29c in breast cancer cells such as proliferation, migration, invasion, colony formation, and 3D growth were evaluated using MTT, transwell chambers, soft agar, and 3D Matrigel culture, respectively. In addition, the luciferase reporter assay was used to check if miR-29c binds the 3′UTR of DNMT3B. The effects of miR-29c on the DNMT3B/TIMP3/STAT1/FOXO1 pathway were also examined using Western blot and methyl-specific qPCR. The specific inhibitor of STAT1, fludarabine, was used to further check the mechanism of miR-29c function in breast cancer cells. Studies on cell functions were carried out in DNMT3B siRNA cell lines.ResultsThe expression of miR-29c was decreased with the progression of breast cancers and was closely associated with an overall survival rate of patients. Overexpression of miR-29c inhibited the proliferation, migration, invasion, colony formation, and growth in 3D Matrigel while knockdown of miR-29c promoted these processes in breast cancer cells. In addition, miR-29c was found to bind 3′UTR of DNMT3B and inhibits the expression of DNMT3B, which was elevated in breast cancers. Moreover, the protein level of TIMP3 was reduced whereas methylation of TIMP3 was increased in miR-29c knockdown cells compared to control. On the contrary, the protein level of TIMP3 was increased whereas methylation of TIMP3 was reduced in miR-29c-overexpressing cells compared to control. Knockdown of DNMT3B reduced the proliferation, migration, and invasion of breast cancer cell lines. Finally, our results showed that miR-29c exerted its function in breast cancers by regulating the TIMP3/STAT1/FOXO1 pathway.ConclusionThe results suggest that miR-29c plays a significant role in suppressing the progression of breast cancers and that miR-29c may be used as a biomarker of breast cancers.Electronic supplementary materialThe online version of this article (10.1186/s13148-018-0495-y) contains supplementary material, which is available to authorized users.

MiR-29c-3p, a target miRNA of LINC01296, accelerates tumor malignancy: therapeutic potential of a LINC01296/miR-29c-3p axis in ovarian cancer

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MiR‐29c protects against inflammation and apoptosis in Parkinson's disease model in vivo and in vitro by targeting SP1

“…Historically, numerous miRNAs have been reported to participate in the regulation of various biological and pathological processes in neurodegenerative diseases, such as PD. Up to now, several studies have demonstrated that miR‐29c (a member of miR‐29 family) is decreased in multiple types of cancers to serve as a tumour suppressor . A recent study by Bai et al showed that the levels of the miR‐29 family, especially miR‐29a and miR‐29c in blood serum were decreased in PD patients .…”

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“…Supporting our hypothesis of hsa-miR-29c-5p being important for establishing the ER positive/luminal breast cancer phenotype by targeting DNMT3A which further leads to hypomethylation of CpGs at ER-associated TFBSs, Chou et al [43] found that GATA3 acts as a TF inducing the expression of the miR-29 family. This and other studies have, however, pointed to a tumor-suppressor role of the miR-29 family in breast cancer as they are typically found higher expressed in less aggressive/better prognosis subtypes and with overexpression in cell lines inhibiting metastasis, proliferation, migration and growth [43][44][45].…”