The Expression And Effects Of Heat Shock Proteins (HSP90) In The Acute Myeloid Leukemia Cells

Objective: To study the expression of HSP90in acute myelocytic leukemia cellsand its relationship with FAB subtypes and prognosis. To explore the effect of theheat shock protein90(HSP90) inhibitor on the acute myelocytic leukemia celllineHL-60and its related mechanism．Methods: RT-PCR was used to detect the mRNA expression of HSP90inmarrow mononuclear cells from80patients with acute myelocytic leukemia (45male,35female), and10healthy volunteers (normal controls, NC). The possible correlationbetween HSP90mRNA and FAB subtypes, and the prognosis was analyzed. Therewas an over-expression of HSP90mRNA in HL-60cell lines, used as positivecontrols. The HL-60cells were treated with different concentrations of17-DMAG.The (OD) value was detected through MTT assay and the inhibition rate wascalculated. The protein level of the signaling molecule Akt and HSP90were evaluatedthrough Western BlotResults:1. The high HSP90mRNA expression was detected in leukemia celllines tested, with HSP90mRNA0.523in HL-60cell line.HSP90mRNA expressionin newly diagnosed AML group (the positive rate100%, the mean level0.523±0.225)was significantly higher than that in normal control (positive rate:100%，mean level:0.193±0.054)(P＜0.05).2. The expression level of HSP90mRNA(positive rate100%, mean level0.243±0.087) in complete remission group were higher than those in normalcontrol,respectively, although they were not statistically significant(P>0.05). Thelevel in remission group was lower than in untreated group (P<0.05).The HSP90mRNA level in relapsed group(the mean level0.875±0.194) was also significantlyhigher than NC(P＜0.05). There was difference in both the levels of HSP90mRNA (P＜0.05).3. The expression level of HSP90mRNA was unequal among different subtypesand the lower level was detected in M3and higher level in M5, but there was nostatistical difference (P>0.05).4. The in vitro effect of17一DMAG with different concentrations and timesinhibit the proliferation of HL-60cell line in a dose and time—dependent.5. After the HL-60were treated with different concentration and the sameoperation times of17一DMAG, the decrease of Akt and HSP90were proved byWestern Blot. The expression of Akt and HSP90were down-regulated as the increaseof17-DMAG density.Conclusions:1. HSP90was expressed both in normal individuals and patients.The expression level was higher in untreated and relapsed AML patients, which couldbecome lower when remission was attained.2. The expression level of HSP90was not associated with FAB subtypes.3. The expression level of HSP90can be used as an index in monitoring anddiagnose AML4.17-DMAG can inhibit the proliferation of the HL-60cell, which may berelated to the depletion of Akt protein by inhibiting HSP90protein in the cells.5. HSP90can be used as a new therapeutic target of leukemia.