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Published on: December 1, 2015
RNA inference-mediated caveolin-1 down-regulation decrease estrogen receptor alpha (ERα) signaling in human mammary
Xi Wang1, Shuang Feng, Hong Zhang
1College of Life Science, Liaoning Normal University, 116029, Dalian, China.
Abstract:
Several evidences support that caveolin-1 is associated with mammary cell transformation and oncogenesis. We have previously reported that a cell line, named MCF10A-ST1 (ST1), which only expressed 30% Cav-1 compared with parental cells MCF10A (human mammary epithelial cell line) was isolated by gene trapping. The decreased expression of Cav-1 is sufficient for phenotypic transformation of MCF10A cells, which involved in the loss of anchorage-dependent growth and migration in nude mice with the existence of E2. The previous study in our lab on microarray assay showed that the expression of cyclin D1 (cell cycle protein) was up-regulated in ST1 cell line. Here, we not only confirmed the results by Western Blot but also demonstrated that Cav-1 down-regulation accelerate the progression of mammary cells from G1 phase into S phase by Flow Cytometry (FCM). This proposed that the Cav-1 down-regulation could change the progress of cell cycle in the mammary cells. Otherwise, microarray assay also showed that the transcription factor (c-Jun) was up-regulated. But, the original carcinoma gene (c-Fos) and transcription factor (AP-1) have not obviously changed compared with MCF10A. ST1 cells obtained the morigenicity in nude mice with the existence of E2, and the immunoprecipitation showed the interactions of Cav-1 with ERα in both MCF10A and ST1. ERα expression was increased as further down-regulation of Cav-1. So, we hypothesize that Cav-1 down-regulation could induce the activation of ERα-associated signaling pathway, in order to adjust the development and proliferation. By siRNA technology, the down regulation of Cav-1 could activate MAP kinase and Akt signaling pathway, including the phosphorylation of ERK1/2 and Akt. However, the mechanism of Cav-1 down-regulation in the early transformation and signaling transduction of mammary epithelial cells is unclear. Here, we report that down-regulation of caveolin-1 protein expression leads to deregulate estrogen receptor alpha (ERα) signaling and consequently early transformation in mammary epithelia.
Insights
Down-regulation of caveolin-1 (Cav-1) in mammary cells promotes cell cycle progression and early transformation. This involves activating estrogen receptor alpha (ERα) signaling pathways, impacting cell proliferation and migration.
Area of Science:
- Cell Biology
- Molecular Oncology
- Biochemistry
Background:
- Caveolin-1 (Cav-1) is implicated in mammary cell transformation and oncogenesis.
- Previous studies identified an MCF10A cell line (ST1) with reduced Cav-1 expression, exhibiting phenotypic transformation.
- Decreased Cav-1 expression is sufficient for transformation, affecting anchorage-dependent growth and migration.
Purpose of the Study:
- To investigate the mechanistic link between caveolin-1 down-regulation and early mammary epithelial cell transformation.
- To elucidate the role of Cav-1 in cell cycle regulation and signaling pathways.
- To explore the interaction between Cav-1 and estrogen receptor alpha (ERα) in mammary cells.
Main Methods:
- Western Blotting to confirm protein expression changes.
- Flow Cytometry (FCM) to analyze cell cycle progression (G1 to S phase).
- Gene expression analysis (microarray) and immunoprecipitation to study protein interactions and signaling pathways.
- siRNA technology to down-regulate Cav-1 expression.
Main Results:
- Down-regulation of Cav-1 accelerates mammary cell cycle progression from G1 to S phase.
- Reduced Cav-1 expression leads to increased cyclin D1 and c-Jun expression.
- Cav-1 interacts with ERα, and its down-regulation increases ERα expression and activates MAP kinase and Akt signaling pathways.
- ST1 cells exhibit tumorigenicity in nude mice, correlating with Cav-1 levels and ERα activity.
Conclusions:
- Down-regulation of caveolin-1 protein expression deregulates estrogen receptor alpha signaling.
- This deregulation contributes to early transformation in mammary epithelial cells.
- Cav-1's role in cell cycle control and signaling pathways is critical for mammary cell homeostasis and oncogenesis.
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