Significance Of SENEX Gene MRNA Expression In Patients With Acute Myeloid Leukemia

Background Acute myeloid leukemia(AML)is the most common type of adult leukemia,originated in the myeloid stem / progenitor cell mutation caused by malignant blood clonal disease.However its etiology still remains poorly understood.Although AML treatment and diagnosis technology has development rapidly,but there are still some patients with treatment problems such as recurrent and refractory.Recently the overall 5-year survival rate of AML patients is only approximately 30 to 40 percent,and refractory recurrent AML patients are lower than 15 percent.Leukemia cells are difficult to completely remove that caused recurrent /refractory problems.Analyzed the reason,we suggested that the existence of a self-protection mechanism in leukemia cells that escaped immune system or chemotherapy.Cells are going into a state of relatively static and stable when under pressure such as internal and external factors called cellular senescence.As research deepens,found that aging does not necessarily lead to irreversible apoptosis.SIPS is spurred by pressure such as internal and external factors that caused aging in advance,but as pressure removed or environmental changed,aging cells may be recovery and into the cell cycle.However studies that indicated that tumor cells were into aging in advance under DNA damage factors such as radiation and chemotherapy.SENEX is an anti-apoptotic new gene associated with cellular senescence.Studies showed that SENEX gene can be triggering senescence by SIPS into cellular senescence has anti-apoptotic and immune-suppressing effect.The characteristics of SENEX gene are helpful to study the problem of relapsed and resistance to chemotherapy in clinic,thus,to aim at SENEX involved in AML development and progress has an important value.Objective The subjects regarded AML patients as the research object.Firstly,to detect the m RNA expression of SENEX gene in acute myeloid leukemia(AML)by q RT-PCR,and then evaluate the characteristics and differences in SENEX gene expression of various stage AML patients and controls.Clear whether the SENEX gene is up-regulated in AML cells,and then we combined with clinicopathological parameters of AML to investigate the clinical significance of SENEX gene expression in AML patients;Using by transfected with Si RNA in vitro experiments to explore whether the SENEX gene in AML by initiating the aging signal pathway,inhibit the role of pro-apoptotic genes to play the role of protection of leukemia cells.Methods Firstly,a total of 67 patients with AML were enrolled in this study,including 21 patients were new diagnosed(AML-ND),27 patients were completely remission in bone marrow(AML-CR)and 19 patients with relapses(AML-Relapse),12 patients with iron deficiency anemia with age-matched non-hematologic malignancies were selected as experimental control group.In this study,SENEX gene m RNA expression of bone marrow mononuclear cells was detected by real-time quantitative PCR in 21 AML-ND patients,27 AML-CR patients,19 AML-Relapse patients and 12 controls,the data was analyzed that the differences in four groups and clinical features and the correlation between the SENEX m RNA expression and clinicopathological parameters and curative effect of AML.Secondly,in vitro experiments,selected cytotoxic drug Ara-c to induce NB4 cell lines to establish cellular senescence model,and the control group was treated with same amount of PBS,and the other study group that treated with si RNA transfected before Ara-c treatment.Then after 72 hours,detection and analysis of SENEX m RNA expression in Ara-c group,Ara-c combined with Si RNA group and controls.In addition,we also detected and analyzed the apoptosis rate of Ara-c treated group,Ara-c combined with Si RNA group and controls.Finally,the expression of SENEX gene in NB4 cell line was silenced by si RNA,and then the expression of pro-apoptotic gene(p53,Caspase-3)in this study group and control group was detected,and the pro-apoptotic genes correlation with SENEX gene was also analyzed.Results 1.SENEX gene expression levels were significantly associated with the progression of AML disease.The level of SENEX m RNA expression in AML-ND and AML-Relapse group was significantly higher than controls,and AML-ND group was also increased compared as AML-CR group.SENEX gene expression levels in various subtype AML patients were analyzed,and then the data showed that the level of SENEX m RNA in subtype of AML-M3 was highest in other subtypes.There was a positive correlation between the expression of SENEX m RNA and the ratio of bone marrow blasts in AML patients.In addition,to analysis the clinical features of patients with AML,after first chemotherapy,we found that SENEX gene expression in AML patients achieved CR(n=14)was significantly lower than patients with no CR(n=7).However,the prognosis of these 7 cases with no CR is all poor.2.In vitro experiment,the expression level of SENEX gene in Ara-c stimulated group was significantly higher than that in PBS control group,and the cells of Ara-c stimulation group were almost in the early stage of apoptosis.However,the percentage of cells at early stage of apoptosis in Ara-c+Si RNA group was significantly decreased than in Ara – c group.3.Si RNA-SENEX transfection,the data showed that silencing down SENEX gene expression could up-regulate the expression of pro-apoptotic gene(p53,Caspase-3).Conclusion Abnormal expression of SENEX gene may be closely related to the development and prognosis of AML.SENEX gene may be involved in apoptotic pathway of AML leukemia cells.SENEX gene may be resistance to apoptosis of leukemia cells by inhibiting pro-apoptotic genes.