Abstract
Abstract Eicosanoids participate in the dysregulation of cell proliferation during tumorigenesis. The up-regulation of cyclooxygenase-2 (COX-2) and down-regulation of 15-prostaglandin dehydrogenase (15-PGDH) have been linked to the switch for a pro-proliferative and pro-angiogenic tumor microenvironment. Previous studies have characterized the effects of increased prostaglandin E2 in tumor progression but the role of many other endogenous lipid mediators has yet to be determined. COX-2 can metabolize arachidonic acid (AA) to hydroxyeicosatetraenoic acids (HETEs), which in turn can be further oxidized by dehydrogenases into oxo-eicosatetraenoic acids (oxo-ETEs). We have previously reported that 11-oxo-ETE and 15-oxo-ETE are major COX-2/15-PGDH derived metabolites formed from human cells expressing COX-2 treated with AA. Although no known G-protein coupled receptor has been reported for either of these metabolites, both 11-oxo- and 15-oxo-ETE have been described from human clinical samples. This study provides a description of the uptake and distribution of 11-oxo-ETE and 15-oxo-ETE as well as their anti-proliferative activity in both human umbilical vein endothelial cells (HUVECs) and LoVo human colon adenocarcinoma cells. Quantification of the intracellular and extracellular levels of 11-oxo- and 15-oxo-ETE was conducted using liquid chromatography electron capture atmospheric pressure chemical ionization mass spectrometry with [13C]-labeled 15-oxo-ETE as an internal standard. The intracellular concentrations of 11-oxo- and 15-oxo-ETE reached peak amounts within 1h followed by a rapid decline. Earlier studies have indicated that glutathione (GSH)-S-transferase further metabolized 11-oxo-ETE to form the 11-oxo-ETE-GSH (OEG)-adduct. In additional experiments, pretreatment with ethacrynic acid (EA), a known inhibitor of GSTs, increased recovery from the cellular extract. In addition, the methyl-ester of both 11-oxo- and 15-oxo-ETE was used for the targeted intracellular delivery of these COX-2/15-PGDH derived eicosanoids. Finally, we have shown that both 11-oxo- and 15-oxo-ETE as well as their methyl ester derivatives significantly inhibit cell proliferation as determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) cell proliferation assay and Bromodeoxyuridine (BrdU) incorporation in multiple human cell lines. The present study has established the cellular uptake of the short-lived COX-2/15-PGDH derived eicosanoids 11-oxo- and 15-oxo-ETE and potent inhibition of new DNA synthesis and proliferation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-10. doi:1538-7445.AM2012-LB-10
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