title: Suppression of phosphoinositide 3-kinase signaling and alteration of multiple ion currents in drug-induced long QT syndrome.
abstract: Many drugs, including some commonly used medications, can cause abnormal heart rhythms and sudden death, as manifest by a prolonged QT interval in the electrocardiogram. Cardiac arrhythmias caused by drug-induced long QT syndrome are thought to result mainly from reductions in the delayed rectifier potassium ion (K(+)) current I(Kr). Here, we report a mechanism for drug-induced QT prolongation that involves changes in multiple ion currents caused by a decrease in phosphoinositide 3-kinase (PI3K) signaling. Treatment of canine cardiac myocytes with inhibitors of tyrosine kinases or PI3Ks caused an increase in action potential duration that was reversed by intracellular infusion of phosphatidylinositol 3,4,5-trisphosphate. The inhibitors decreased the delayed rectifier K(+) currents I(Kr) and I(Ks), the L-type calcium ion (Ca(2+)) current I(Ca,L), and the peak sodium ion (Na(+)) current I(Na) and increased the persistent Na(+) current I(NaP). Computer modeling of the canine ventricular action potential showed that the drug-induced change in any one current accounted for less than 50% of the increase in action potential duration. Mouse hearts lacking the PI3K p110α catalytic subunit exhibited a prolonged action potential and QT interval that were at least partly a result of an increase in I(NaP). These results indicate that down-regulation of PI3K signaling directly or indirectly via tyrosine kinase inhibition prolongs the QT interval by affecting multiple ion channels. This mechanism may explain why some tyrosine kinase inhibitors in clinical use are associated with increased risk of life-threatening arrhythmias.
authors.affiliation: Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY 11794, USA.
authors.forename: Zhongju
authors.initials: Z
authors.lastname: Lu
authors.forename: Chia-Yen C
authors.initials: CY
authors.lastname: Wu
authors.forename: Ya-Ping
authors.initials: YP
authors.lastname: Jiang
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Ballou
authors.forename: Chris
authors.initials: C
authors.lastname: Clausen
authors.forename: Ira S
authors.initials: IS
authors.lastname: Cohen
authors.forename: Richard Z
authors.initials: RZ
authors.lastname: Lin
mesh_terms: D000200:Action Potentials; D000818:Animals; D020746:Calcium Channels, L-Type / Q000187:drug effects / Q000378:metabolism; D058534:Class I Phosphatidylinositol 3-Kinases; D003198:Computer Simulation; D051668:Delayed Rectifier Potassium Channels / Q000187:drug effects / Q000378:metabolism; D004285:Dogs; D004562:Electrocardiography; D005260:Female; D008133:Long QT Syndrome / Q000139:chemically induced* / Q000201:enzymology / Q000235:genetics / Q000503:physiopathology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008955:Models, Cardiovascular; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000201:enzymology; D019869:Phosphatidylinositol 3-Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000633:toxicity*; D018570:Risk Assessment; D015398:Signal Transduction / Q000187:drug effects*; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
chemical_list: D020746:Calcium Channels, L-Type; D058534:Class I Phosphatidylinositol 3-Kinases; D051668:Delayed Rectifier Potassium Channels; D019869:Phosphatidylinositol 3-Kinases; D018129:Phosphatidylinositol Phosphates; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D026941:Sodium Channel Blockers; D015222:Sodium Channels; C060974:phosphatidylinositol 3,4,5-triphosphate; C546639:Pik3ca protein, mouse; C546640:Pik3cb protein, mouse