title: Carboxyamidotriazole-induced inhibition of mitochondrial calcium import blocks capacitative calcium entry and cell proliferation in HEK-293 cells.
abstract: Blocking calcium entry may prevent normal and pathological cell proliferation. There is evidence suggesting that molecules such as carboxyamidotriazole, widely used in anti-cancer therapy based on its ability to block calcium entry in nonexcitable cells, also have antiproliferative properties. We found that carboxyamidotriazole and the capacitative calcium entry blocker 2-aminoethoxydiphenyl borate inhibited proliferation in HEK-293 cells with IC50 values of 1.6 and 50 microM, respectively. Capacitative calcium entry is activated as a result of intracellular calcium store depletion. However, non-capacitative calcium entry pathways exist that are independent of store depletion and are activated by arachidonic acid and diacylglycerol, generated subsequent to G protein coupled receptor stimulation. We found that carboxyamidotriazole completely inhibited the capacitative calcium entry and had no effect on the amplitude of arachidonic-acid-activated non-capacitative calcium entry. However, investigation of the effects of carboxyamidotriazole on mitochondrial calcium dynamics induced by carbachol, capacitative calcium entry and exogenously set calcium loads in intact and digitonin-permeabilized cells revealed that carboxyamidotriazole inhibited both calcium entry and mitochondrial calcium uptake in a time-dependent manner. Mitochondrial inner-membrane potential was altered by carboxyamidotriazole treatment, suggesting that carboxyamidotriazole antagonizes mitochondrial calcium import and thus local calcium clearance, which is crucial for the maintenance of capacitative calcium entry.
authors.affiliation: Department of Pharmacology and Physiology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA.
authors.forename: Olivier
authors.initials: O
authors.lastname: Mignen
authors.forename: Christine
authors.initials: C
authors.lastname: Brink
authors.forename: Antoine
authors.initials: A
authors.lastname: Enfissi
authors.forename: Aditi
authors.initials: A
authors.lastname: Nadkarni
authors.forename: Trevor J
authors.initials: TJ
authors.lastname: Shuttleworth
authors.forename: David R
authors.initials: DR
authors.lastname: Giovannucci
authors.forename: Thierry
authors.initials: T
authors.lastname: Capiod
mesh_terms: D001896:Boron Compounds / Q000494:pharmacology; D002118:Calcium / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D017136:Ion Transport / Q000187:drug effects; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors; D014230:Triazoles / Q000494:pharmacology*
chemical_list: D001896:Boron Compounds; D002121:Calcium Channel Blockers; D014230:Triazoles; C062058:carboxyamido-triazole; C109986:2-aminoethoxydiphenyl borate; D002118:Calcium