Dataset Information

Progesterone reverses the mesenchymal phenotypes of basal phenotype breast cancer cells via a membrane progesterone receptor mediated pathway.

ABSTRACT:

Introduction

Basal phenotype breast cancers (BPBC) are often associated with apparent epithelial to mesenchymal transition (EMT). The role of progesterone (P4) in regulating EMT of BPBC has not been reported.

Methods

The EMT relevant biology was investigated in vitro using human BPBC cell models (MDA-MB468 and MDA-MB231) with P4, PR agonist (RU486), and PR antagonist (R5020) treatments. The essential role of membrane progesterone receptor alpha (mPRalpha) in the P4-regulated EMT was demonstrated by knocking down the endogenous gene and/or stably transfecting exogenous mPRalpha gene in the BPBC cell models.

Results

The expression of snail and down-stream EMT proteins such as occludin, fibronectin, and E-cadherin was significantly regulated by P4 incubation, which was accompanied by cell morphological reversion from mesenchymal to epithelial phenotypes. In searching for the cell mediator of P4' action in the MDA-MB468 (MB468) cells, it was found that mPRalpha but not the nuclear PR has an essential role in the P4 mediated EMT inhibition. Knocking down the expression of mPRalpha with specific siRNA blocked the P4's effects on expression of the EMT proteins. In another BPBC cell line--MDA-MB231 (MB231), which is mPRalpha negative by Western blotting--P4 treatment did not alter cell proliferation and EMT protein expressions. Introduction of the exogenous mPRalpha cDNA into these cells caused cell proliferation, but not EMT, to become responsive to P4 treatment. In further studies, it was found that activation of the PI3K/Akt pathway is necessary for the P4-induced EMT reversion. To define the potential inter-mediate steps between mPRalpha and PI3K, we demonstrated that mPRalpha, caveolin-1 (Cav-1), and epidermal growth factor receptor (EGFR) are colocalized in the membrane of caveolar vesicle and the P4-repressed EMT in MB468 cells can be blocked by EGFR inhibitor (AG1478) and PI3K inhibitor (wortmannin).

Conclusions

Our data suggest that the signaling cascade of P4 induced mesenchymal repression is mediated through mPRalpha and other caveolae bound signaling molecules namely Cav-1, EGFR, and PI3K. This novel finding may have great impact on fully understanding the pathogenesis of BPBC and provide an essential clue for developing a targeted therapeutic strategy for treatment of BPBC.

SUBMITTER: Zuo L

PROVIDER: S-EPMC2917029 | biostudies-literature | 2010

REPOSITORIES: biostudies-literature

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Publications

Progesterone reverses the mesenchymal phenotypes of basal phenotype breast cancer cells via a membrane progesterone receptor mediated pathway.

Zuo Lian L Li Wei W You Shaojin S

Breast cancer research : BCR 20100611 3

<h4>Introduction</h4>Basal phenotype breast cancers (BPBC) are often associated with apparent epithelial to mesenchymal transition (EMT). The role of progesterone (P4) in regulating EMT of BPBC has not been reported.<h4>Methods</h4>The EMT relevant biology was investigated in vitro using human BPBC cell models (MDA-MB468 and MDA-MB231) with P4, PR agonist (RU486), and PR antagonist (R5020) treatments. The essential role of membrane progesterone receptor alpha (mPRalpha) in the P4-regulated EMT w ...[more]

PMID: 20540763

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Project description:BACKGROUND:Breast cancer currently is the most frequently diagnosed neoplasm and the leading cause of death from cancer in women worldwide, which is mainly due to metastatic disease. Increasing our understanding of the molecular mechanisms leading to metastasis might thus improve the pharmacological management of the disease. Epithelial-mesenchymal transition (EMT) is a key factor that plays a major role in tumor metastasis. Some pro-inflammatory cytokines, like IL-6, have been shown to stimulate phenotypes consistent with EMT in transformed epithelial cells as well as in carcinoma cell lines. Since the EMT is one of the crucial steps for metastasis, we studied the effects of metformin (MTF) on EMT. METHODS:Cytotoxic effect of MTF was evaluated in eight primary breast cancer cell cultures by crystal violet assay. EMT markers and downstream signaling molecules were measured by Western blot. The effect of MTF on cell proliferation and cell migration were analyzed by MTT and Boyden chamber assays respectively. RESULTS:We observed that the response of cultured breast cancer primary cells to MTF varied; mesenchymal cells were resistant to 10?mM MTF and expressed Vimentin and SNAIL, which are associated with a mesenchymal phenotype, whereas epithelial cells were sensitive to this MTF dose, and expressed E-cadherin but not mesenchymal markers. Further, exposure of mesenchymal cells to MTF down-regulated both Vimentin and SNAIL as well as cell proliferation, but not cell migration. In an in vitro IL-6-induced EMT assay, primary breast cancer cells showing an epithelial phenotype underwent EMT upon exposure to IL-6, with concomitant activation of STAT3 and NF-?B; addition of MTF to IL-6-induced EMT reversed the expression of the mesenchymal markers Vimentin and SNAIL, decreased pSTAT3 Y705 and pNF-?B S536 and increased E-cadherin. In addition, downregulation of STAT3·activation was dependent on AMPK, but not NF-?B phosphorylation. Further, MTF inhibited cell proliferation and migration stimulated by IL-6. CONCLUSION:These results suggest that MTF inhibits IL-6-induced EMT, cell proliferation, and migration of primary breast cancer cells by preventing the activation of STAT3 and NF-?B. STAT3 inactivation occurs through AMPK, but not NF-?B.

Project description:Epithelial-to-mesenchymal transition (EMT) and its reversed process mesenchymal-to-epithelial transition (MET) play a critical role in epithelial plasticity during development and cancer progression. Among important regulators of these cellular processes are non-coding RNAs (ncRNAs). The imprinted DLK1-DIO3 locus, containing numerous maternally expressed ncRNAs including the lncRNA maternally expressed gene 3 (MEG3) and a cluster of over 50 miRNAs, has been shown to be a modulator of stemness in embryonic stem cells and in cancer progression, potentially through the tumor suppressor role of MEG3. In this study we analyzed the expression pattern and functional role of ncRNAs from the DLK1-DIO3 locus in epithelial plasticity of the breast. We studied their expression in various cell types of breast tissue and revisit the role of the locus in EMT/MET using a breast epithelial progenitor cell line (D492) and its isogenic mesenchymal derivative (D492M). Marked upregulation of ncRNAs from the DLK1-DIO3 locus was seen after EMT induction in two cell line models of EMT. In addition, the expression of MEG3 and the maternally expressed ncRNAs was higher in stromal cells compared to epithelial cell types in primary breast tissue. We also show that expression of MEG3 is concomitant with the expression of the ncRNAs from the DLK1-DIO3 locus and its expression is therefore likely indicative of activation of all ncRNAs at the locus. MEG3 expression is correlated with stromal markers in normal tissue and breast cancer tissue and negatively correlated with the survival of breast cancer patients in two different cohorts. Overexpression of MEG3 using CRISPR activation in a breast epithelial cell line induced partial EMT and enriched for a basal-like phenotype. Conversely, knock down of MEG3 using CRISPR inhibition in a mesenchymal cell line reduced the mesenchymal and basal-like phenotype of the cell line. In summary our study shows that maternally expressed ncRNAs are markers of EMT and suggests that MEG3 is a novel regulator of EMT/MET in breast tissue. Nevertheless, further studies are needed to fully dissect the molecular pathways influenced by non-coding RNAs at the DLK1-DIO3 locus in breast tissue.

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Dataset Information

Progesterone reverses the mesenchymal phenotypes of basal phenotype breast cancer cells via a membrane progesterone receptor mediated pathway.

Introduction

Methods

Results

Conclusions

Publications

Progesterone reverses the mesenchymal phenotypes of basal phenotype breast cancer cells via a membrane progesterone receptor mediated pathway.

Similar Datasets

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