Abstract 5671: Cyclooxygenase-2-dependent and -independent effects of etoricoxib in human cervical cancer cell lines
Authors: Tripathi Shweta , Dwarkanath B.s. , Chandna Sudhir , Saluja Daman , Chopra Madhu 
Published: February 2011

Abstract
Introduction: Cyclooxygenase (COX), also known as prostaglandin endoperoxidase or prostaglandin G/H synthase, is a rate limiting enzyme involved in the conversion of arachidonic acid to prostaglandins. Two forms of cyclooxygenase, COX-1 and COX-2, have been identified. COX-1 is constitutively expressed in many tissues, while COX-2 is an inducible enzyme involved in inhibition of apoptosis, potentiation of cell growth and angiogenesis and as such is a target for drug development. Recently clinical, cellular and animal experimental studies have indicated its relevance to tumor invasion and metastasis. Etoricoxib is a novel non-steroidal anti-inflammatory drug (NSAIDs) that stops the production of inflammatory prostaglandins, without stopping the production of prostaglandins that protect the stomach and intestine. There is persuasive evidence that COX-2 inhibitors suppress tumor growth due to their ability to inhibit cell proliferation and induce apoptosis. The purpose of this study was to elucidate the mechanism of action by which Etoricoxib induces the arrest of Human cervical tumor cells growth.
Methods: Cell viability was measured by MTT assay and trypan blue exclusion method. Apoptosis was examined by DNA fragmentation and Comet Assay and the distribution of cells in the cell cycle was estimated by flow cytometry. Western Blotting was used to explore various mechanisms of Etoricoxib induced apoptosis.
Results: Etoricoxib in the concentration range of 100-200μM was 2-3 folds more cytotoxic (MTT assay) in the tumorigenic cell lines HeLa (cervical COX-2 positive), C-33A (cervical COX-2 negative), U-87, MCF-7, Hep3B, MiaPaCa-2 as compared to the non-tumorigenic cell lines (Cos-7, NIH3T3, HEK). These results correlated well with the observations on inhibition of cell growth and were comparable to the results reported for Celecoxib, another COX-2 selective inhibitor. Interestingly, Methotrexate widely used anticancer agent, showed 70-80% cytotoxicity in the non tumorigenic cell lines as compared to only 20% cytotoxicity with etoricoxib, suggesting thereby that it is selectively toxic to tumor cells unlike many other anticancer drugs. Comet assay results in HeLa cells showed a dose and time dependent increase in DNA damage suggestive of drug induced DNA damage at early times, followed by apoptotic DNA fragmentation and necrotic DNA degradation at later times. Western blotting results showed up regulation of Caspase-3, indicative of the role of etoricoxib in inhibition of HeLa cell growth via. apoptosis, The Bcl-2/BAX ratio in HeLa cells decreased with increasing concentrations of etoricoxib at different time points. Also, In conclusion this study shows that in the human cervical cancer cell lines, Hela & C33A, Etoricoxib suppresses proliferation, induces apoptosis and causes cell death by DNA damage in both Cox-2 dependent as well as independent pathway in a dose and time dependent manner.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5671.