Clozapine, a neuroleptic agent, inhibits Akt by counteracting Ca2+/calmodulin in PTEN-negative U-87MG human glioblastoma cells.
Clozapine (CZP), a dibenzodiazepine derivative with a piperazinyl side chain, is in clinical use as an antipsychotic drug. This study investigated the effect of CZP on the modulation of the PI3K/Akt/GSK-3beta pathway in PTEN-negative U-87MG glioblastoma cells. Treatment with CZP rapidly inhibited the basal and EGF-induced phosphorylation of Akt. The inhibition of Akt resulted in the dephosphorylation of GSK-3beta and increased GSK-3beta kinase activity. A voltage-sensitive Ca(2+) channel blocker and calmodulin (CaM) antagonists inhibited Akt phosphorylation, whereas elevation of the intracellular Ca(2+) concentration prevented CZP-induced dephosphorylation of Akt and GSK-3beta, suggesting that Ca(2+)/CaM participates in the inhibition of Akt by CZP in U-87MG cells. In addition, similar to LY294002, CZP arrested cell cycle progression at G0/G1 phase, which was accompanied by decreased expression of cyclin D1. The reduction in the cyclin D1 level induced by CZP was abrogated by the inhibition of GSK-3beta, the inhibition of proteasome-dependent proteolysis, or an increase in the intracellular Ca(2+) concentration. These results suggest that the antipsychotic drug CZP modulates the PI3K/Akt/GSK-3beta pathway by counteracting Ca(2+)/CaM in PTEN-negative U-87MG glioblastoma cells.
Shin
Soon Young
SY
Division of Molecular and Life Science, College of Science and Technology, Hanyang University, Ansan, South Korea.
Choi
Byeong Hyeok
BH
Ko
Jesang
J
Kim
Se Hyun
SH
Kim
Yong Sik
YS
Lee
Young Han
YH
D014150:Antipsychotic Agents / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D045744:Cell Line, Tumor; D003024:Clozapine / Q000494:pharmacology*; D003598:Cytoskeletal Proteins / Q000378:metabolism; D017353:Gene Deletion; D005909:Glioblastoma / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism; D051059:PTEN Phosphohydrolase / Q000235:genetics; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured
D014150:Antipsychotic Agents; D002147:Calmodulin; D003598:Cytoskeletal Proteins; C512806:NIN protein, human; D009687:Nuclear Proteins; D051057:Proto-Oncogene Proteins c-akt; D051059:PTEN Phosphohydrolase; D003024:Clozapine; D002118:Calcium