Effect Of Total Saponins Of Panaxginseng On JAK2,STAT5 Expression Of K562 Cells

Objective:Leukemia is a very common malignancy in human being, whose pathogeny is due to abnormal proliferation and disdifferentiation of bone marrow hematopoietic stem cells . So far, traditional chemotherapy and radiotherapy are still the main therapies, but they have many side effects and high recurrence rate, and greatly damage the normal immunity and hematopoiesis too. Many Chinese herbal medicines can affect proliferation and differentiation of hematopoietic stem cells at the level of protein and molecule, then achieve the effect of recovering the hematopoietic function. Total saponins of Panax ginseng (TSPG) is one of the main effective ingredient extracted from Panax Ginseng. Our previous study suggested that TSPG could not only improve the proliferation and signal transduction of hamatopoietic stem/progenitor cell but also inhibited the proliferation of leukemia cells, and induced them apoptosis and differentiation toward the mature cell. But these mechanism remain to be studied. We surposed that JAK2,STAT5 may play vital role in the control of proliferation , differentiation and apoptosis of K562 cell by TSPG treatment, due to JAK2/STAT5 signal pathway is very important in regulation of the proliferation , differentiation and apoptosis of leukemic cell. In this study, we examined the effect of TSPG on the expression of the JAK2,STAT5 in the K562 cell by the method of immuocytochemistry , Western blotting and ELISA as well, and established a foundation for pursuit the molecule target of TSPG acting on proliferation , differentiation and apoptosis of leukemic cell, and provided a guidance for clinic treatment of hematologic desease.Methods:1. to culture the leukemia cell (K562 cell line) in vitro.2. to detect the effect of TSPG on expression of JAK2,STAT5 in K562 cell using immuocytochemistry.3. To assay the content of the JAK2 protein in plasma and STAT5 protein in plasma and nucleus of K562 cell before or after the TSPG treatment by means of ELISA.4. To observe the effect of TSPG on the JAK2 expression in plasma and STAT5 expression in plasma and nucleus of K562 cell by means of Western blottingResults:1. By means of Immunocytochemical stain for JAK2, plasma of K562 cell showed brown in the control group, while the stain of K562 cytoplasm was light after TSPG 200 mg/L treatment for 12 h. The average optical density of cytoplasm in the TSPG group (0.178±0.08 )was significantly lower than that in the control group (0.245±0.06) (P<0.05) .2. By means of ELISA and western blotting , the expression of JAK2 in the K562 cell was gradually decreased in time-dependent manner after TSPG treatment.3. By means of Immunocytochemical stain for STAT5, The cytoplasma and nucleus of K562 cell in control group is weakly stained; after stimulated by 200 mg/L TSPG for 12h, both cytoplasma and nucleus of K562 cell is darkly stained. Compared with control group, the amount of STAT5 in cytoplasma and nucleus of K562 cell induced by 200μg/ml TSPG is increased in time-dependent manner.4. By means of ELISA and Western blotting, the expression of STAT5 in the plasma and nuclus of K562 cell was increased gradually after TSPG treatment.Conclusion:1. TSPG decreased the expression of JAK2 protein, this might relate to the apoptosis induction and growth inhibition of K562 cell by TSPG treatment.2. TSPG increased the expression of STAT5 in K562 cell, this might be the one of the mechanism by which TSPG induce K562 cell to differentiate into erythroid cell.