N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride) (W-7) causes increases in intracellular free Ca2+ levels in bladder female transitional carcinoma (BFTC) cells.
The effect of N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride) (W-7), a widely used calmodulin inhibitor, on intracellular free Ca2+ levels ([Ca2+]i) in bladder female transitional cancer (BFTC) cells was examined using fura-2 as a Ca2+ dye. W-7 (10-1000 microM) caused an increase in [Ca2+]i in a concentration-dependent manner with an EC50 of 75 microM. The [Ca2+]i response was composed of an initial rise and a sustained plateau without significant decaying during the measurement of 250 seconds. Extracellular Ca2+ removal dramatically decreased the Ca2+ signals by 50-90%. W-7 (100 microM) failed to induce a [Ca2+]i increase in Ca(2+)-free medium after pretreatment with thapsigargin (1 microM), an endoplasmic reticulum Ca2+ pump inhibitor; conversely, W-7 pretreatment abolished the Ca2+ release induced by thapsigargin. Addition of 3 mM Ca2+ increased [Ca2+]i after preincubation with 100 microM W-7 in Ca(2+)-free medium. W-7-induced Ca2+ release was not altered by inhibiting phospholipase C with 2 microM 1-(6-((17b-3-methoxyestra-1,3,5 (10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione) (U73122). Together, this study shows that W-7 caused [Ca2+]i increases in human bladder cancer cells by releasing intracellular Ca2+ from the endoplasmic reticulum and also by causing extracellular Ca2+ influx with the later playing a dominant role. The W-7-induced intracellular Ca2+ release was uncoupled to a prior elevation in intracellular levels of inositol 1,4,5-trisphosphate (IP3).
Jan
C R
CR
Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Taiwan 813. crjan@isca.vghks.gov.tw
Yu
C C
CC
Huang
J K
JK
D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002295:Carcinoma, Transitional Cell / Q000378:metabolism*; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004963:Estrenes / Q000494:pharmacology; D005260:Female; D005456:Fluorescent Dyes; D016257:Fura-2; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000037:antagonists & inhibitors / Q000378:metabolism; D011760:Pyrrolidinones / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology*; D019284:Thapsigargin / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors; D001749:Urinary Bladder Neoplasms / Q000378:metabolism*
D003470:Culture Media; D004791:Enzyme Inhibitors; D004963:Estrenes; D005456:Fluorescent Dyes; D011760:Pyrrolidinones; D013449:Sulfonamides; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C017967:W 7; D019284:Thapsigargin; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D010738:Type C Phospholipases; D002118:Calcium; D016257:Fura-2