Anti-proliferative and apoptotic effects of celecoxib on human chronic myeloid leukemia in vitro J. Subhashini, S.V.K. Mahipal, P. Reddanna * Department of Animal Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India Received 17 May 2004; received in revised form 30 October 2004; accepted 2 November 2004 Abstract Celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, is the only non-steroidal anti-inflammatory drug so far which has been approved by the FDA for adjuvant treatment of patients with familial adenomatous polyposis. The molecular mechanism responsible for the anti-cancer effects of celecoxib is not fully understood. There is little data on the potential role of COX-2 in lymphoma pathogenesis. In view of the reported induction of apoptosis in cancer cells by cyclooxygenase-2 inhibitors, the present study is undertaken to test the effect of celecoxib on human chronic myeloid leukemia cell line, K562 and other hematopoietic cancer cell lines like Jurkat (human T lymphocytes), HL60 (human promyelocytic leukemia) and U937 (human macrophage). Treatment of these cells with celecoxib (10–100 mM) dose-dependently, reduced cell growth with arrest of the cell cycle at G0/G1 phase and induction of apoptosis. Further mechanism of apoptosis induction was elucidated in detail in K562 cell line. Apoptosis was mediated by release of cytochrome c into the cytoplasm and cleavage of poly (ADP-ribose) polymerase-1 (PARP-1). This was followed by DNA fragmentation. The level of anti-apoptotic protein Bcl-2 was decreased without any change in the pro-apoptotic Bax. Celecoxib also inhibited NF-kB activation. Celecoxib thus potentiates apoptosis as shown by MTT assay, cytochrome c leakage, PARP cleavage, DNA fragmentation, Bcl-2 downregulation and possibly by inhibiting NF-kB activation. q 2004 Elsevier Ireland Ltd. All rights reserved. Keywords: Celecoxib; Chronic myelogenous leukemia; Apoptosis; PARP; Cytochrome c; Bcl-2; NF-kB 1. Introduction Cancer is the largest single cause of death in both men and women, claiming over 6 millions each year in the world. For many years, the cytotoxic actions of chemotherapeutic drugs were ascribed solely to their ability to induce genotoxic damage. During the past decade, however, the evidence is gradually accumu- lating that many cancer chemotherapeutic agents induce cell death by a process known as programmed cell death, or apoptosis. Although, the precise path- ways by which chemotherapeutic agents kill tumors have been controversial, the killing of tumors through the induction of apoptosis has been now recognized as a novel strategy for the identification of anti-cancer drugs [1]. Thus, much effort has been directed towards 0304-3835/$ - see front matter q 2004 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.canlet.2004.11.002 Cancer Letters 224 (2005) 31–43 www.elsevier.com/locate/canlet * Corresponding author. Tel./fax: C91 40 23010745. E-mail addresses: preddanna@yahoo.com (P. Reddanna), prsl@uohyd.ernet.in (P. Reddanna).