title: The Hsp90 inhibitor geldanamycin selectively sensitizes Bcr-Abl-expressing leukemia cells to cytotoxic chemotherapy.
abstract: The Bcr-Abl fusion protein drives leukemogenesis and can render leukemia cells resistant to conventional chemotherapy. Geldanamycin (GA), a drug which destabilizes Hsp90-associated proteins, depletes cells of Bcr-Abl, an Hsp90 client, but not of Abl. Both HL60 cells transfected with Bcr-Abl and naturally Ph1-positive K562 leukemia cells are resistant to most cytotoxic drugs, but were found to be sensitive to GA. Furthermore, GA sensitized Bcr-Abl-expressing cells to doxorubicin (DOX) and paclitaxel (PTX). In contrast, in parental HL60 cells, 90 nM GA inhibited PARP cleavage, nuclear fragmentation, and cell death caused by 500 ng/ml DOX. Like GA, STI 571 (an inhibitor of the Abl kinase) sensitized Bcr-Abl-expressing cells to DOX. Unlike GA, STI 571 did not antagonize the cytotoxic effects of DOX in parental HL60 cells. These results indicate that sensitization of Bcr-Abl-expressing cells, but not desensitization of HL60 cells, depends on inhibition of Bcr-Abl. Thus, GA differentially affects leukemia cells depending on their Bcr-Abl expression and selectively increases apoptosis in Bcr-Abl-expressing cells.
authors.affiliation: Department of Developmental Therapeutics, Medicine Branch, National Cancer Institute, NIH, Bethesda and Rockville, MD 20892, USA.
authors.forename: M V
authors.initials: MV
authors.lastname: Blagosklonny
authors.forename: T
authors.initials: T
authors.lastname: Fojo
authors.forename: K N
authors.initials: KN
authors.lastname: Bhalla
authors.forename: J S
authors.initials: JS
authors.lastname: Kim
authors.forename: J B
authors.initials: JB
authors.lastname: Trepel
authors.forename: W D
authors.initials: WD
authors.lastname: Figg
authors.forename: Y
authors.initials: Y
authors.lastname: Rivera
authors.forename: L M
authors.initials: LM
authors.lastname: Neckers
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D016227:Benzoquinones; D004317:Doxorubicin / Q000494:pharmacology; D004347:Drug Interactions; D004351:Drug Resistance; D016044:Fusion Proteins, bcr-abl / Q000096:biosynthesis / Q000187:drug effects*; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors*; D006801:Humans; D047029:Lactams, Macrocyclic; D007938:Leukemia / Q000378:metabolism / Q000473:pathology*; D017239:Paclitaxel / Q000494:pharmacology; D011809:Quinones / Q000494:pharmacology*; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D016227:Benzoquinones; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D011809:Quinones; D004317:Doxorubicin; D016044:Fusion Proteins, bcr-abl; D017239:Paclitaxel; C001277:geldanamycin