| ObjectiveMulti - drug resistance ( MDR) is a main reason to cause leukemia chemotherapy failed . The MDR is characterized by cross - resistance to avariety of drugs with different structure and function ,Its creation has primarily below several aspects reason : The (1) depends on the energy of the cell membrane efflux pump , such as P-gp, MRP(multi -drug resistance relevant protein) ; The (2) straches with the cytosolic enzymes such as GSTs(glutathion -S - thansferas-es) ; The (3) lies the MDR ,such as LRP(lung resistant relevant protein) , that lead with the cell nucleus spot protein ; The (4) lies the MDR , such as TOPO II (topoisomerase II) that lead with the enzymes inside the cell nucleus. Among them , P-gp is the more classical one ,as to its mechanism study too more very clear. But to not the classical one ,such as GSTs etc. investigation is still little.GSTs may contribute to the cellular resistance by detoxifying cytostatic a-gents . According to its in the already decided in cell of different, GSTs generally can be divided into a , u, , IT ( PI) , 6 and membrane combinating micro-somal 5 types, among them, GST - Pi is the most close with malignant tumor relation, inviting to account for 90% of its total amount . The drug resistant function of GST-Pi is mainly caused by its detoxifying , its mechanisms thinks now below several aspects : (I) GSTs may catalyse the conjugation of reduced glutathione (GSH) to electrophilic molecules , such as the alkylating agents , which may enhance the solubility and excretion of the drug ; (2) GSTs may also detoxify the radicals formed by drug , e. g. the oxygen and hydroxyl radicals generated by anthracyclines ; (3) GSTs can also sequester drugs by direct binding , e. g. of alkylation agents and steroids ; (4) GSTs still has the activity of GSH peroxidase . In this paper , to understand the relation between GST-Pi and MDR in AL ,we analyzed the expression of GST-Pi and P-gp in 160 cases AL byimmunohistochemistry , at the same time , the GST-Pi activity in 25 cases were also examined by Habig etc methods . The results showed that the expression of GST-Pi and P-gp in relapsed / refractory groups were higher than in primary / sensitive groups , there were close relation between the expression of GST-Pi and P-gp in relapsed / refractory groups , GST-Pi and P-gp were the important factors in the effect of prognosis in AL; the co - expression of GST-Pi and P-gp lead to a poorer prognosis . there were a higher relation between the expression and activity of GST-Pi.Methods1. cell culture : Drug resistant cell lines OVCAR3 and K - 562 were cultured routinely in our laboratory . Exponentially growing cells were used for all experiments . The tow cell lines were used as positive controls for GST-Pi and P-gp , respectively.2. Patient samples ; 160 cases AL patients ,95 were male , 55 were female average age was 41 , all cases were confirmed according to FAB diagnostic standard . Among them , there were 104 AML cases and 50 ALL cases . According to the outcome , 92 primary / sensitive cases and 68 relapsed / refractory cases . 10 of non - tumor cases were used as normal controls . Standard induced remission chemotherapy were used.3. Isolation of mononuclear cells ; 3 - 5 ml heparipheral bone marrow fluid (blasts >70% ) were collected , mononuclear cells were isolated with Ficoll density gradient centrifugation.4. Detection of GST-Pi and P-gp expression : GST-Pi and P-gp expression were monitored by immunohistochemistry and were judged positive ceil > 25% and 20% , respectively.5. Detection of GST-Pi activity :GST-Pi activity was monitored by Habig etc. methods.6. Statistical methods:X test ,t test and liner correlation analysis were used.Results1. Expression of GST-Pi and P-gp in primary/sensitive groups and relapsed/refractory groupsThe total positive rates of GST-Pi and P-gp were 40. 6% and 53. 1% , respectively ; the positive rates of GST-Pi in primary/sensitive groups and relapsed/refractory groups were 24. 5% and...
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