NPC-15199, a novel anti-inflammatory agent, mobilizes intracellular Ca ²⁺ in Bladder Female Transitional Carcinoma (BFTC) cells

This report demonstrates that NPC-15199 [(N-(9-fluorenylmethoxycarbonyl)L-leucine)], a novel anti-inflammatory agent, increases intraecllular Ca ²⁺ concentration ([Ca ²⁺ ] _i ) in human bladder female transitional cancer (BFTC) cells. Using fura-2 as a Ca ²⁺ probe, NPC-15199 (0.1-2 mM) was found to increase [Ca ²⁺ ] _i concentration-dependently. The response saturated at 2-5 mM NPC-15199. The [Ca ²⁺ ] _i increase comprised an initial rise, a slow decay, and a plateau. Ca ²⁺ removal partly inhibited the Ca ²⁺ signals. In Ca ²⁺ -free medium, pretreatment with 1 mM NPC-15199 abolished the [Ca ²⁺ ] _i increase induced by 1 μM thapsigargin (an endoplasmic reticulum Ca ²⁺ pump inhibitor); and after pretreatment with thapsigargin, NPC-15199-induced Ca ²⁺ release was dramatically inhibited. This indicates that NPC-15199 released internal Ca ²⁺ mostly from the endoplasmic reticulum. Adding 3 mM Ca ²⁺ increased [Ca ²⁺ ] _i in cells pretreated with 1 mM NPC-15199 in Ca ²⁺ -free medium. Together, the findings suggest that in BFTC bladder cancer cells, NPC-15199 induced Ca ²⁺ release from the endoplasmic reticulum and activating Ca ²⁺ entry.