title: Arsenic trioxide and proteasome inhibitor bortezomib synergistically induce apoptosis in leukemic cells: the role of protein kinase Cdelta.
abstract: Arsenic trioxide (ATO) and proteasome inhibitor bortezomib have been successfully applied to treat acute promyelocytic leukemia (APL) and multiple myeloma (MM), respectively. Their synergistic effects with other anticancer drugs have been widely studied. Here, we investigated the potential synergy of bortezomib and ATO on Bcr-Abl(+) leukemic K562 cells. The results showed that cotreatment of bortezomib at 32 nM, a half concentration for growth arrest, and ATO at 1 microM, a dose with no significant cytotoxic effect, synergistically induced apoptosis in the cell line, followed by enhanced mitochondrial dysfunction, release of cytochrome c and apoptosis-inducing factor, caspase-3 cleavage and degradation of poly-adenosine diphosphate-ribose polymerase together with the decreased Bcr-Abl protein. These two drugs synergistically induced proteolytic activation of protein kinase Cdelta (PKCdelta) with enhanced activation of two mitogen-activated protein kinases phospho-c-Jun NH(2)-terminal kinase and p38. The specific PKCdelta inhibitor rottlerin markedly decreased bortezomib plus ATO-induced apoptosis, suggesting that PKCdelta plays an important role in bortezomib plus ATO-induced apoptosis. Moreover, apoptosis synergy of bortezomib and ATO could also be seen in some kinds of acute leukemic cell lines and primary cells. Totally, our results indicate that combined regimen of bortezomib and ATO might be a potential therapeutic remedy for the treatment of leukemia.
authors.affiliation: Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Rui-Jin Hospital, Shanghai, China.
authors.forename: H
authors.initials: H
authors.lastname: Yan
authors.forename: Y-C
authors.initials: YC
authors.lastname: Wang
authors.forename: D
authors.initials: D
authors.lastname: Li
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: W
authors.initials: W
authors.lastname: Liu
authors.forename: Y-L
authors.initials: YL
authors.lastname: Wu
authors.forename: G-Q
authors.initials: GQ
authors.lastname: Chen
mesh_terms: D000328:Adult; D017209:Apoptosis / Q000187:drug effects*; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology*; D001897:Boronic Acids / Q000494:pharmacology*; D000069286:Bortezomib; D045744:Cell Line, Tumor; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007938:Leukemia / Q000188:drug therapy* / Q000473:pathology; D008875:Middle Aged; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010087:Oxides / Q000494:pharmacology*; D011480:Protease Inhibitors / Q000494:pharmacology; D051745:Protein Kinase C-delta / Q000378:metabolism / Q000502:physiology*; D011719:Pyrazines / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D001152:Arsenicals; D001897:Boronic Acids; D010087:Oxides; D011480:Protease Inhibitors; D011719:Pyrazines; D000069286:Bortezomib; D051745:Protein Kinase C-delta; D020928:Mitogen-Activated Protein Kinases; D000077237:Arsenic Trioxide