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Proteomic analysis reveals that 14-3-3sigma is down-regulated in human breast cancer cells
A S Vercoutter-Edouart1, J Lemoine, X Le Bourhis
1Equipe Facteurs de Croissance, Laboratoire de Biologie du Développement, UPRES-EA 1033, Villeneuve d'Ascq, France.
Abstract:
The class of molecular chaperones known as 14-3-3 is involved in the control of cellular growth by virtue of its apparent regulation of various signaling pathways, including the Raf/mitogen-activated protein kinase pathway. In breast cancer cells, the sigma form of 14-3-3 has been shown to interact with cyclin-dependent kinases and to control the rate of entry into mitosis. To test for a direct role for 14-3-3 in breast epithelial cell neoplasia, we have quantitated 14-3-3 protein levels using a proteomic approach based on two-dimensional electrophoresis and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF). We show here that 14-3-3sigma protein is strongly down-regulated in the prototypic breast cancer cell lines MCF-7 and MDA-MB-231 and in primary breast carcinomas as compared with normal breast epithelial cells. In contrast, levels of the alpha, beta, delta, or zeta isoforms of 14-3-3 were the same in both normal and transformed cells. The data support the idea that 14-3-3sigma is involved in the neoplastic transition of breast epithelial cells by virtue of its role as a tumor suppressor; as such, it may constitute a robust marker with clinical efficacy for this pathology.
Insights
14-3-3sigma protein, a key regulator of cell growth, is significantly reduced in breast cancer cells and tumors. This downregulation suggests 14-3-3sigma acts as a tumor suppressor, potentially serving as a clinical marker for breast cancer.
Area of Science:
- Molecular biology
- Cancer research
- Proteomics
Background:
- 14-3-3 proteins are molecular chaperones regulating cellular growth and signaling pathways like Raf/MAPK.
- The 14-3-3sigma isoform interacts with cyclin-dependent kinases, controlling cell cycle progression into mitosis.
- Previous studies suggest a role for 14-3-3 in breast cancer, necessitating further investigation.
Purpose of the Study:
- To investigate the role of 14-3-3 proteins in breast epithelial cell neoplasia.
- To quantify 14-3-3 protein levels in normal and cancerous breast cells and tissues.
Main Methods:
- Proteomic analysis utilizing two-dimensional electrophoresis.
- Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry for protein quantitation.
Main Results:
- 14-3-3sigma protein levels were significantly decreased in breast cancer cell lines (MCF-7, MDA-MB-231) and primary breast carcinomas compared to normal breast epithelial cells.
- Levels of other 14-3-3 isoforms (alpha, beta, delta, zeta) remained unchanged between normal and cancerous cells.
Conclusions:
- The data indicate that 14-3-3sigma is involved in the neoplastic transformation of breast epithelial cells.
- 14-3-3sigma functions as a tumor suppressor in breast cancer.
- Downregulated 14-3-3sigma may serve as a valuable clinical biomarker for breast cancer detection and prognosis.