Inhibition of store-operated calcium entry contributes to the anti-proliferative effect of non-steroidal anti-inflammatory drugs in human colon cancer cells

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit proliferation and an giogenesis in colorectal cancer. We examined a possible involvement of stor e-operated calcium (SOC) entry in human colon carcinoma cells (HRT-18), whi ch require calcium for proliferation. Acetyl-salicylic-ac id (ASA), mefenam ic acid (MEF) and sulindac sulfide (SUS) inhibited cell proliferation with the following order of potency: SUS > MEF > > ASA, SUS but not MEF and ASA induced apoptosis following low-dose treatment, Furthermore, SUS and MEF si gnificantly altered the cell cycle distribution. The ability of NSAIDs to i nhibit SOC entry was assessed by measuring the intracellular calcium concen tration ([Ca2+](i)) in response to calcium store depletion using the endopl asmic calcium ATPase inhibitor thapsigargin. SUS and MEF, but not ASA signi ficantly inhibited SOC entry. A causal link between SOC entry inhibition an d anti-proliferative activity was tested using the inorganic SOC entry inhi bitor La3+ and the specific organic inhibitor N-1-n-octyl-3,5-bis-(4-pyridy l)triazole (DPT), Both La3+ and DPT inhibited cell proliferation and SOC en try. Analogous to MEF, the anti-proliferative effect of DPT was mediated by cell cycle arrest and not by induction of apoptosis, These data indicate a role of SOC entry for cell proliferation in cancer cells and suggest a nov el anti-proliferative NSAID mechanism in addition to its known influence on lipid metabolism. (C) 2001 Wiley-Liss, Inc.