Study On Reversion Of Multidrug Resistance In Human Leukemic Cell Line K562/ADM By Paeonol

Object:To investigate the reversion of multidrug resistance in human leukemic cell line K562/ADM by Paeonol and to explore the possible mechanism.Methods:The 3,4,5-dimethylth-iazol-2-yl-2,5-diphenyl-tetrazolium bromide (MTT) assay was used to determine the suppression of the proliferation of K562,K562/ADM cells by Paeonol in vitro. The IC50 of ADM after exposed to Paeonol within non-toxicity doses and low-toxicity doses was determined. The effects of Paeonol on the expression of mdr-1,MRP,LRP were assessed by reverse transcription-polymerase chain reaction (RT-PCR). Immunohistochemistry was used to determine the expression of P-gp and P53,bcl-2 after Paeonol treatment. TdT-mediated dUTP nick end labeling was used to determine the changes of cell apoptosis by Paeonol. Western blot was used to determine the expression of P38 Kinase in P38 MAP Kinase signal pathway.Results:It was observed that Paeonol can restrain the proliferation of K562,K562/ADM cells in the concentration from 5 to 100μgml-1 and reduce the cell IC50 of ADM under the non-toxicity doses 5μgml-1 and the low-toxicity doses 12.5μgml-1. After exposure to Paeonol combined with ADM for 48h,the gene expression of mdr-1,MRP,LRP was depressed to a certain extent according to the result of RT-PCR and the expression of P-gp,P53 and bcl-2 was also depressed according to the result of Immunohistochemistry; the expression of P38 Kinase which is one of the members of P38 MAP Kinase signal pathway was reduced by Paeonol. The AI was significantly increased after Paeonol combined with ADM.Conclusion:Paeonol may down-regulate the gene expression of mdr-1,MRP,LRP and the protein expression of P-gp; Paeonol may also down-regulate the protein expression of P53,bcl-2, so that it could promote cell apoptosis. Paeonol may reduce the expression of P38 Kinase in P38 MAP Kinase signal pathway, Therefore, Paeonol may promote cell apoptosis to reverse the multidrug resistance by down-regulating the expression of gene and protein; It may be another possible mechanism of reversion of the multidrug resistance that Paeonol may reduce the expression of P38 Kinase in P38 MAP Kinase signal pathway.