ABSTRACT
<p><b>OBJECTIVE</b>To investigate the role of Apaf-1 gene promoter methylation and apoptosis inhibitor protein Apollon in pathogenesis of acute leukemia (AL) and their clinical significance.</p><p><b>METHODS</b>Methylation 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.</p><p><b>RESULTS</b>The 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.</p><p><b>CONCLUSION</b>Abnormal methylation of Apaf-1 gene promotor and high expression of Apollon might involved in leukemogenesis.</p>