OBJECTIVETo investigate the role of Apaf-1 gene promoter methylation and apoptosis inhibitor protein Apollon in pathogenesis of acute leukemia (AL) and their clinical significance.

METHODSMethylation specific PCR (MSP) was used to detect the methylation status of Apaf-1 gene promoter in 53 AL patients (28 AML, 10 ALL and 15 relapsed) and 10 healthy or nonmalignant blood diseases patients as control. RT-PCR was used to detect the expression levels of Apaf-1 mRNA and immunocytochemistry to detect the expression levels of Apollon protein.

RESULTSThe abnromal methylation of Apaf-1 gene promotor in AL was 18/53(33.9%). No Apaf-1 mRNA was detected in methylation positive patients. Only one case in healthy and nonmalignant individuals was deletion of Apaf-1 mRNA expression without abnormal methylation. The positive methylation rate in AL bone marrow mononuclear cells was significantly higher than that in controls (P < 0.05). The expressin levels of Apollon protein in AL patients was higher than that in control (P < 0.05). The positive methylation ratio and Apollon protein level were higher in white blood cell count > 10 × 10(9)/L than in ≤ 10 × 10(9)/L (P < 0.05). There is a positive correlaiton between positive methylation ratio and Apollon protein expression in AL patients.

CONCLUSIONAbnormal methylation of Apaf-1 gene promotor and high expression of Apollon might involved in leukemogenesis.