Semester

Summer

Date of Graduation

2011

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Biology

Committee Chair

Phillip Keeting

Abstract

Breast cancer remains one of the leading causes of cancer related death among women worldwide. Numerous reports have provided evidence of a role of inflammation in the onset and progression of many cancers, including breast cancer. A mechanism that leads to inflammation involves the arachidonic acid (AA) pathway, which leads to the production of a group of pro-inflammatory bioactive lipids, collectively known as the eicosanoids. Despite evidence of AA and the eicosanoids in cancer, limited work has been done on the enzyme cytosolic phospholipase A2 (cPLA2) that provides the unesterified AA that can be used for eicosanoid generation. The present studies were undertaken to investigate the expression of the cPLA 2 isozymes cPLA2alpha, -beta, -gamma, in the human breast cancer cell lines MDA-MB 231 and MCF-7, and in the immortalized non-tumorigenic human breast cell line MCF-10A. Additionally, surgically removed cancerous human breast tissue was also assessed for cPLA2 isozyme expression. The present study indicates the presence of the cPLA2 isozymes -alpha, -beta, - gamma in the tumorigenic breast cancer cell lines MDA-MB 231 and MCF-7. The isozymes were not detected in the non-tumorigenic MCF-10A cell line. Stimulation of the cells by Ca2+ ionophore A 23187 elicited a redistribution of the Ca2+ dependent cPLA2 isoforms -alpha and -beta within the MDA-MB 231 and the MCF-7 cells. AACOCF3, a cPLA2alpha..inhibitor, pretreatment caused a decreased cPLA2alpha signal, observed also in assays of cPLA 2beta and cPLA2gamma. Assays of cPLA2 isozyme expression in the human breast tissues were unable to demonstrate the presence of any of the cPLA2 isozyme proteins. The results of this research indicate that the tumorigenic human breast cell lines MDA-MB 231 and MCF-7 express the cPLA2alpha, cPLA2beta and cPLA 2gamma proteins, and that the cPLA2 proteins could not be detected in the non-tumorigenic human breast cell line, MCF-10A. The A23187 elicited redistribution of cPLA2alpha and cPLA2beta proteins within the cells, and decreased signal in AACOCF3 pretreated specimens provides evidence supporting antisera specificity. Although cPLA2alpha is recognized to be the principal enzyme responsible for AA release leading to eicosanoid biosynthesis, cPLA2beta and cPLA2gamma, which share ∼30% homology with cPLA2alpha, may also participate in releasing AA and could support pro-inflammatory eicosanoid biosynthesis. Further investigations will be necessary to fully define the regulation of the cPLA2 isozymes in the MDA-MB 231 and MCF-7 cells. The expression of the cPLA2 isozymes in cancerous human breast tissue remains undescribed.

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