Study On The Mechanism Of G-CSF-priming-regimen In Treating AML Subtypes Hard To Cure

Background and objective:Relapse AML,refractory AML,AML in the old and secondary AML are all AML subtypes hard to cure.They characterize in insensitive to chemotherapy,short duration of CR(complete remission), easy to relapse.Yamada et al brought forward CAG regimen,which has been proved effective in treating AML subtypes hard to cure.This regimen can treat these AML subtypes with the CR rate at 62%-86%,media survival of 8-17 months,the adverse reaction of CAG regimen is more moderate than that of standard chemotherapy or salvage therapy.Patients' life quality gets better when they are treated with CAG regimen.The basic theory of CAG regimen is as follows.(1) The mechanism of CAG regimen is to spur quiescent cells into the S-phase,so that tumor cells are more sensitive to chemical therapy.(2) CFU-AML can be killed preferentially by prolonged exposure to low dosage of Ara-c in the presence of G-CSF with relative preservation of normal CFU-GM.(3) the Acla-mediated cytotoxicity of CFU-AML,which is effective in treating MDR cells,is reported to be enhanced by short-term combination with G-CSF. (4) The low dose of medcine can reduce the mortality associated with chemical therapy,and increase the endurance of patients.Method:Part one:study on the optimum time of the use of G-CSF in vitro Methods by using U937 cell as a model,observe the changes of cell morphology;and cell growth inhibition were evaluated by methyl thiazolyltetrazolium(MTT) assay;the ratio of apoptosis and cells in S-phase by flow cytometry assay. Part two:study on the mechanism of different priming regimens(CAG HAG DAG) in vitroMethods by using U937 cell as a model,after incubated with CAG,HAG,DAG,observe the changes of cell morphology;and cell growth inhibition were evaluated by methyl thiazolyltetrazolium(MTT) assay;the ratio of apoptosis and cells in S-phase by flow cytometry assay.Part three:primary study on the mechanism of CAG regimen in vivo. Observe the outcome,adverse reaction of the 2AML patients treated with CAG regimen.Mononuclear cells were isolated from heparinized bone marrow samples.Observation the the changes of cell morphology;the ratio of apoptosis and cells in S-phase by flow cytometry assay.Results:Part one:After cultured with CAG,apoptosis can be observed in the U937 cell.Cell growth inhibition are almost the same in the different groups after 48 hours.The ratio of apoptosis cells is associated with that of S-phase cells.Part two:Cell growth inhibition are almost the same in the three groups after cultured with different drugs for 48hours.The ratio of apoptosis and S-phase cells are higher in CAG and HAG group than in DAG group.Part three:The two patient with AML achieved complete remission after CAG regimen.Apoptosis cells can be found in the bone marrow smear and by the flow cytometry assay.Conclusion:U937 cells can be predicatively restrained by priming-regimen in vitro.The mechanism of CAG and HAG is mainly to induce apoptosis in vitro,while that of DAG is to enhance the cytotoxocity of chemical drugs. G-CSF used with Ara-C and DNR at the same time is demonstrated to be effective in vitro.CAG regimen treats AML by means of inducing apoptosis, its relationship with cell cycle is under further study.