GPAT2 expression regulates arachidonic acid induced apoptosis in the breast adenocarcinoma cell line MDA-MB-231.

FERREMI, FIORELLA; CATTANEO, ELIZABETH R; GONZALEZ BARO, MARIA R.; MONTANARO, MAURO A

Waterville Valley

Congreso; Gordon Research Conferences Molecular and Cellular Biology of Lipids; 2019

GRC

Arachidonic acid -derived eicosanoids and theirdownstream pathways have been implicated in cell growth control and apoptoticpathways in breast cancer, promoting malignancy in several types of tumors.Glycerol-3-phosphate acyltransferase 2 (GPAT2) is an acyltransferase that,differing from the other GPAT isoforms, exclusively uses arachidonoyl-CoA as asubstrate for glycerolipid synthesis. Because high levels of arachidonicacid induce apoptosis, whereas metabolic pathways that diminish the content ofunesterified arachidonic acid may prevent it, we focused our studies on the role of GPAT2 onthe regulation of apoptosis in breast cancer. Using RNAi technology,we silenced GPAT2 in breast cancer derived MDA-MB-231 cells, which endogenouslyexpress high levels of GPAT2.  Previously, we had demonstrated that GPAT2 isexpressed in several types of human cancers, and the expression in the MDA-MB-231cell line contributed to the tumor phenotype. Treating these cell lines for 2days with 100 µM arachidonic acid decreased the cell proliferation rate andpromoted apoptosis in MDA-SH (GPAT2-silenced)cells, compared to the GPAT2-expressingMDA-SCR control cells (TUNEL assay), suggesting that GPAT2 prevents apoptosisin MDA cells by sequestering free arachidonic acid. To understand therelationship between GPAT2 expressionand the apoptosis induction triggered by arachidonic acid, we measured the mRNAexpression levels of genes that are involved in arachidonic acid utilizationand eicosanoid biosynthesis, such as AKR1C3(encoding prostaglandin F synthase), ALOX5(encoding arachidonate 5-lipoxygenase) and EPHX2(encoding epoxide hydrolase 2), and used flow cytometry to study the inductionof apoptosis triggered by arachidonic acid. Our results clearly show that GPAT2 silencing induces the expressionof other arachidonic acid metabolizing enzymes, link GPAT2 with arachidonicacid induced apoptosis, and provide information about the molecular mechanismsthrough which GPAT2 might contribute to the control of tumor growth. Funding: Universidad Nacional de La Plata 11/M-202, Agencia Nacional dePromoción Científica y Tecnológica PICT-2014 3214 and PICT-2017 3877,Argentina.