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Slug-upregulated miR-221 promotes breast cancer progression through suppressing E-cadherin expression.

ABSTRACT: It is generally regarded that E-cadherin is downregulated during tumorigenesis via Snail/Slug-mediated E-cadherin transcriptional reduction. However, this transcriptional suppressive mechanism cannot explain the failure of producing E-cadherin protein in metastatic breast cancer cells after overexpressing E-cadherin mRNA. Here we reveal a novel mechanism that E-cadherin is post-transcriptionally regulated by Slug-promoted miR-221, which serves as an additional blocker for E-cadherin expression in metastatic tumor cells. Profiling the predicted E-cadherin-targeting miRNAs in breast cancer tissues and cells showed that miR-221 was abundantly expressed in breast tumor and metastatic MDA-MB-231 cells and its level was significantly higher in breast tumor or MDA-MB-231 cells than in distal non-tumor tissue and low-metastatic MCF-7 cells, respectively. MiR-221, which level inversely correlated with E-cadherin level in breast cancer cells, targeted E-cadherin mRNA open reading frame (ORF) and suppressed E-cadherin protein expression. Depleting or increasing miR-221 level in breast cancer cells induced or decreased E-cadherin protein level, leading to suppressing or promoting tumor cell progression, respectively. Moreover, miR-221 was specifically upregulated by Slug but not Snail. TGF-? treatment enhanced Slug activity and thus increased miR-221 level in MCF-7 cells. In summary, our results provide the first evidence that Slug-upregulated miR-221 promotes breast cancer progression via reducing E-cadherin expression.

SUBMITTER: Pan Y

PROVIDER: S-EPMC4865839 | biostudies-other | 2016

REPOSITORIES: biostudies-other

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Slug-upregulated miR-221 promotes breast cancer progression through suppressing E-cadherin expression.

Pan Yi Y Li Jing J Zhang Yaqin Y Wang Nan N Liang Hongwei H Liu Yuan Y Zhang Chen-Yu CY Zen Ke K Gu Hongwei H

Scientific reports 20160513

It is generally regarded that E-cadherin is downregulated during tumorigenesis via Snail/Slug-mediated E-cadherin transcriptional reduction. However, this transcriptional suppressive mechanism cannot explain the failure of producing E-cadherin protein in metastatic breast cancer cells after overexpressing E-cadherin mRNA. Here we reveal a novel mechanism that E-cadherin is post-transcriptionally regulated by Slug-promoted miR-221, which serves as an additional blocker for E-cadherin expression i ...[more]

PMID: 27174021

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Project description:Breast malignancy remains one of the most common causes of cancer-associated mortalities among women. MicroRNA (miR)-221 and miR-222 are homologous miRs and have a substantial impact on cancer progression. In the present study, the regulatory mechanisms of miR-221/222 and its target annexin A3 (ANXA3) in breast cancer cells were investigated. Breast tissue samples were collected to evaluate the expression patterns of miR-221/222 levels in breast cancer cell lines and cancer tissues according to clinical characteristics. The levels of miR-221/222 were increased or decreased in cancer cell lines compared with normal breast cell lines according to cell line subtype. Subsequently, the changes in the progression and invasion of breast cancer cells were investigated using cell proliferation, invasion assay, gap closure and colony formation assays. Western blotting of cell cycle proteins and flow cytometry were performed to evaluate the possible pathway of miR-221/222 and ANXA3 axis. Chemosensitivity tests were performed to explore the suitability of the miR-221/222 and ANXA3 axis as a therapeutic target in breast cancer. The expression levels of miR-221/222 were associated with aggressive characteristics of breast cancer subtypes. Cell transfection assay demonstrated the regulation of breast cancer proliferation and invasiveness by miR-221/222. MiR-221/222 directly targeted the 3'-untranslated region of ANXA3 and suppressed the expression of ANXA3 at the mRNA and protein levels. In addition, miR-221/222 negatively regulated cell proliferation and the cell cycle pathway in breast cancer cells by targeting ANXA3. In combination with adriamycin, downregulation of ANXA3 may sensitize adriamycin-induced cell death to induction of persistent G2/M and G0/G1 arrest. Decreased expression of ANXA3 through increased expression of miR-221/222 reduced breast cancer progression and increased the effectiveness of the chemotherapy drug. The present results indicated the miR-221/222 and ANXA3 axis to be a possible novel therapeutic target for the treatment of breast cancer.

Dataset Information

Slug-upregulated miR-221 promotes breast cancer progression through suppressing E-cadherin expression.

Publications

Slug-upregulated miR-221 promotes breast cancer progression through suppressing E-cadherin expression.

Similar Datasets

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