[Study on signal transduction pathway in differentiation and apoptosis of leukemia cells induced by heat shock protein inhibitor].
OBJECTIVE
To explore the signal transduction pathway in the differentiation and apoptosis of leukemia cells induced by heat shock protein 90 (HSP90) inhibitor 17-Allyl amide-17-demethoxygeldanamycin (17AAG).


METHODS
Kasumi-1 cells were treated with increasing concentrations or exposure time of 17AAG. The total kit protein (CD117), phosphorylated kit protein and its downstream signaling molecules were measured by Western blot analysis. Mutated kit protein from control and 17AAG-treated Kasumi-1 cells was immunoprecipitated and immunoblotted for associated chaperones.


RESULTS
Total kit protein and kit activity were decreased in 17AAG treated cells, but c-kit mRNA level was not. Total AKT protein and phospho-AKT, as well as phospho-STAT3 were rapidly down-regulated in Kasumi-1 cell after treatment with 17AAG. There was no change in total STAT3 protein. Immunoprecipitation showed that 1 microM 17AAG treatment for 1 hour caused kit associated HSP90 decrease and HSP70 increase.


CONCLUSIONS
17AAG-induced apoptosis of Kasumi-1 cells is associated with a decline in Asn822Lys mutated kit protein level and phosphorylated kit, and with a downregulation in its downstream activated signaling molecules involved in proliferation. AKT is a client protein of HSP90. The changes of kit associated HSP90 and HSP70 satisfy the circulation mode of molecular chaperone complex.
Yu
Wen-Juan
WJ
Institute of Hematology and Blood Diseases Hospital, CAMS and PUMC, Tianjin 300020, China.
Rao
Qing
Q
Wang
Min
M
Tian
Zheng
Z
Xu
Zhi-Fang
ZF
Wang
Jian-Xiang
JX
D017209:Apoptosis / Q000187:drug effects; D016227:Benzoquinones / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors*; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D047029:Lactams, Macrocyclic / Q000494:pharmacology*; D007938:Leukemia / Q000378:metabolism* / Q000473:pathology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D014407:Tumor Cells, Cultured
D016227:Benzoquinones; D018841:HSP90 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D050796:STAT3 Transcription Factor; C112765:tanespimycin; D019009:Proto-Oncogene Proteins c-kit; D051057:Proto-Oncogene Proteins c-akt