Expression of death-associated protein kinase gene and methylation status of promoter region in acute leukemia / 中国实验血液学杂志

ABSTRACT

This study was purpose to investigate the expression of death-associated protein kinase (DAPK) gene in acute leukemia (AL) patients and the methylation status of its promoter region through experiments of DAPK methylation and expression, and to analyze the relation between them. The expression of DAPK gene in leukemia cells and normal bone marrow cells was detected by RT-PCR; the methylation status of DAPK gene promoter region in cells from AL patients and leukemia cell lines HL-60 and U937 was detected by nested methylation specific PCR (n-MSP); 2 randomly primers selected from randomly amplified products of second round nMS-PCR were cloned and sequenced in professional company. The results showed that the DAPK gene expressed in bone marrow specimens of all 10 normal controls, with average value of expression 0.92 ± 0.18, while the average value of DAPK expression in bone marrow specimens of AL patients was 0.61 ± 0.40 which was lower than that in normal controls (P < 0.05). The low or deletion of DAPK mRNA expression were found in bone marrow specimens of 9/17 (52.94%) cases of ALL and 42/102 (41.18%) cases of AML. The cell line U937 showed normal expression of DAPK gene, while cell line HL-60 showed the expression detection of DAPK gene. The methylation of DAPK promoter region existed in 33 out of bone marrow specimens of 102 AML patients and in 8 out of bone marrow specimens of 17 ALL patients, the methylation rates were 32.4% (33/102) and 47% respectively. The DAPK promoter region in bone marrow of 7 normal controls was unmethylated, while DAPK promoter region in U937 cells and HL-60 cells were unmethylated and methylated respectively. The DAPK mRNA expression in ALL and AML patients significantly negatively correlated with the methylation of its promoter region (r = -0.855, P < 0.05, in AML patients and r = -0.343, P < 0.05, in AML patients) suggesting the close relationship between them. It is concluded that the methylation of DAPK gene promoter region relates with abnormal expression or detection of DAPK mRNA in AL patients.