Research On Expression And Promoter Methylation Of Tumor Suppressor Gene P27 In Acute Leukemia

Objective:To investigate the changes of tumor suppressor gene p27 and promoter methylation status in Acute leukemia(AL) patients,as well as explore their role in the development of AL and the relationship that exists between them,which provide the basis of molecular biology to fully understand the pathogenesis of AL, and also provide corresponding laboratory data for further diagnosis and targeted therapy of AL.Methods:Collected 65 cases of AL patients with newly diagnosed in February 2008～October 2009 as disease group,of which 34 cases were male,31 cases were female.The median age is 38.1 years old,ranging from 5 to 80 years old.65 cases include:acute myeloblastic leukemia(AML) 38 cases(M₀ lcases M₁ 2 cases,M₂ 11 cases,M₃ 10 cases,M₄ 6 cases,M₅ 6 cases,M₆ 2 cases),acute lymphoblastic leukemia(ALL) 24 cases,1 case of acute plasma cell leukemia,2 case of acute biphenotypic leukemia.41 patients with benign blood diseases as control group,of which 23 cases were male,18 cases were female.The median age is 32.5 years old, ranging from 12 to 65 years old.41 cases include:iron deficiency anemia 22 cases, idiopathic thrombocytopenic purpura 13 cases,hemolytic anemia 5 cases,1 case of primary hypersplenism.We used RT-PCR and MSP technology to research the mRNA expression level and promoter methylation of p27 gene in bone marrow mononuclear cells of AL patients.The results were statistically analyzed using SPSS 11.5 software package.Result:1,The results of p27 gene expression in AL patients showed that:65 cases of newly diagnosed AL patients,24 cases positive for p27 gene expression,the positive rate was 36.9%;41 cases of the control group,36 cases were positive for p27 gene expression,the positive rate was 87.8%.AL group compared with the control group have significant difference(P＜0.05).â‘¡The positive rates of p27 gene expression in AML and ALL group were 34.2%and 37.5%,which is lower than the control group,AML and ALL group to part compared with the control group,the differences both have statistically significance(P＜0.05);AML group compared with ALL group,the difference was no statistically significance(P＞0.05).â‘¢Comparing p27 gene expression positive rate of≥14 years old and＜14 years old AL patients, and also compared with the positive rate of p27 gene expression in male and female patients,there was no statistically significant difference(P＞0.05);Comparing p27 gene expression positive rate of peripheral blood white blood cell count≥20×10⁹/L and＜20×10⁹/L of AL patients,also compared with the positive rate of p27 gene expression in patients with extramedullary infiltration and with no extramedullary infiltration,and the difference has statistically significance(P＜0.05).The relevance analysis have shown that the relationship of p27 gene expression positive rate and peripheral blood white blood cell count and extramedullary infiltration was a negative correlation(r=-0.284 and -0.300,P＜0.05).2,The study results of p27 gene promoter methylation status in AL patients showed that:â‘ in the 65 cases of newly diagnosed AL patients,3 cases were detected for the p27 gene promoter methylation positive and methylation positive rate was 4.62%;41 cases of control group,there was no detectable p27 gene promoter methylation,methylation positive rate was 0.0%.AL group compared with the control group,the difference has no statistical significance(P＞0.05).â‘¡AML and ALL groups p27 gene promoter methylation rates were 5.26%and 4.17%,ALL group compared with the control group,the difference has no statistical significance(P＞0.05);AML group compared with the control group,the difference has no statistical significance(P＞0.05);AML compared with ALL groups,the difference was not significant(P＞0.05).3,The results on the relationship of p27 gene expression and promoter methylation in AL patients have shown:41 cases of p27 mRNA negative expression was detected in AL group,and only 3 cases with p27 gene promoter methylation,and the occurrence of the 3 cases the expression of p27 mRNA samples were negative. The difference has no statistically significant.Conclusion:1,There is p27 mRNA expression deletion in AL patients,and p27 expression deletion is existent in the AML and ALL at the same time,the relationship of p27 mRNA expression and peripheral blood white blood cell count or extramedullary infiltration was a negative correlation,suggesting that loss of p27 expression is the mechanisms of occurrence and development of AL.2,In our study,there is p27 gene promoter methylation in AL patients,but the methylation-positive rate is low,compared with the control group,the difference has no statistically significant.3,In our study,p27 gene promoter methylation-positive rate of AL patients is low,therefore,p27 gene promoter methylation is one of the mechanisms,whether induced p27 gene expression deletion or not still need further research.