Chidamide Combined with(+)-JQ-1 to Kill MLL-Rearrangement Acute Myeloid Leukemia Cells by Disrupting the DNA Damage Response Pathway
Objective:To investigate the mechanism of DNA damage and repair in MLL-rearranged acute myeloid leukemia(MLL-r AML)cells by the combination of Chidamide and the BRD4 inhibitor(+)-JQ-1.Methods:MLL-r AML cell lines Molm-13,MV4-11 and non-MLL-r AML cell line Kasumi were divided into control group(contr),Chidamide group(chida),(+)-JQ-1 group and Combination group(combi),respectively.Cell viability of Molm-13 was measured by CCK-8 to determine optimal the concentrations of Chidamide and(+)-JQ-1.The cell cycle was detected by flow cytometry,and apoptosis-related factors Bcl-2,Bax and caspase-3 were detected by Western blot.DNA damage marker γH2AX was detected by immunofluorescence.The protein expressions of DNA damage factor γH2AX,DNA damage checkpoint kinases p-ATR,p-CHK1,p-ATM,p-CHK2 and DNA damage repair factors Rad51 and 53BP1 were detected by Western blot.The expression of DNA damage repair factors Rad51 and 53BP1 mRNA was detected by qRT-PCR.Results:Under the treatment of Chidamide(300 nmol/L)and(+)-JQ-1(400 nmol/L),the proportion of G1 phase cells in MLL-r AML cell lines Molm-13 and MV4-11 was increased in combination group compared with control group.In non-MLL-r AML cell line Kasumi,compared with control group,the proportion of G1 phase cells in combination group was increased(P＜0.05).In Molm-13 and MV4-11 cell lines,compared with control group,the expression level of DNA damage marker γH2AX in combination group was increased(P＜0.05).The expression levels of DNA damage checkpoint and damage repair factors p-ATR,p-CHK1,p-ATM,p-CHK2,Rad51,53BP1 were decreased(P＜0.05).In Kasumi cell line,compared with control group,there was no significant change in the expression of some of the above factors in combination group(P＞0.05),but the expression trend of some factors was opposite.In MLL-r AML cell lines Molm-13 and MV4-11,compared with control group,the expression levels of Bax and caspase-3 protein were increased in combination group,while the expression levels of Bcl-2 protein were decreased(P＜0.05).In non-MLL-r AML cell line Kasumi,there was no significant change in apoptotic factor protein expression in combination group compared with control group(P＞0.05).Conclusion:Chidamide combined with(+)-JQ-1 can inhibit the proliferation of MLL-r AML cells,inhibit the initiation of protective self-repair of these leukemia cells by inhibiting the DNA damage response pathway,and ultimately increase the apoptosis of these cells,but non-MLL-r AML cells have no similar results.
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