Novel effects of gossypol, a chemical contraceptive in man: mobilization of internal Ca(2+) and activation of external Ca(2+) entry in intact cells.
The effect of gossypol on Ca(2+) signaling in Madin Darby canine kidney (MDCK) cells was investigated by using fura-2 as a Ca(2+) probe. Gossypol evoked a rise in cytosolic free Ca(2+) levels ([Ca(2+)](i)) concentration-dependently between 2 and 20 microM. The response was decreased by external Ca(2+) removal. In Ca(2+)-free medium pretreatment with gossypol nearly abolished the [Ca(2+)](i) increase induced by carbonylcyanide m-chlorophenylhydrazone (CCCP), a mitochondrial uncoupler, and thapsigargin, an inhibitor of the endoplasmic reticulum Ca(2+) pump; but pretreatment with CCCP and thapsigargin only partly inhibited gossypol-induced Ca(2+) release. Addition of 3 mM Ca(2+) induced a [Ca(2+)](i) increase after pretreatment with 5 microM gossypol in Ca(2+)-free medium. This Ca(2+) entry was decreased by 25 microM econazole, 50 microM SKF96365 and 40 microM aristolochic acid (a phospholipase A(2) inhibitor). Pretreatment with aristolochic acid inhibited 5 microM gossypol-induced internal Ca(2+) release by 55%, but suppression of phospholipase C with 2 microM 1-(6-((17beta-3-methoxyestra-1,3, 5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione) had no effect. Gossypol (5 microM) also increased [Ca(2+)](i) in human bladder cancer cells and neutrophils. Collectively, we have found that gossypol increased [Ca(2+)](i) in MDCK cells by releasing Ca(2+) from multiple Ca(2+) stores in a manner independent of the production of inositol-1,4,5-trisphosphate, followed by Ca(2+) influx from external space.
Jan
C R
CR
Department of Medical Education and Research, Kaohsiung Veterans General Hospital, 386 Ta Chung 1st Rd., Kaohsiung, Taiwan. crjan@isca.vghks.gov.tw
Lin
M C
MC
Chou
K J
KJ
Huang
J K
JK
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D002460:Cell Line; D003272:Contraceptive Agents, Male / Q000494:pharmacology*; D003600:Cytosol / Q000378:metabolism; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D006072:Gossypol / Q000494:pharmacology*; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D007668:Kidney; D009504:Neutrophils; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D011760:Pyrrolidinones / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors; D001749:Urinary Bladder Neoplasms
D003272:Contraceptive Agents, Male; D004791:Enzyme Inhibitors; D004963:Estrenes; D007295:Inositol Phosphates; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D010741:Phospholipases A; D010738:Type C Phospholipases; D006072:Gossypol; D002118:Calcium