The Effects Of Matrine On The Expression Of MICA In K562and K562/ADM Cell Lines And Its Impact On NK Cytotoxicity

Objective:Leukemia is a malignant cloning disease of hematopoietic stem cells. The methods of treatment mainly include chemotherapy, radiation therapy, hematopoietic stem cell transplantation and molecular target therapy, immunotherapy, but the relapse of leukemia after treatment and multiple resistance is currently one of the difficulties in the treatment. In recent years, with the deep research of immune pathogenesis of leukemia, immunotherapy has been playing an important role in leukemia therapy, especially in the areas of minimal residue disease. Leukemia cells which produce the tolerance to chemotherapy drug and to immune cells directly affect the effect of immunotherapy. NK cells form the first line of defense in tumor immune, and is got the attention in leukemia immunotherapy. NKG2D is the activating receptors on NK cells, which cross linking with its ligand will activate the NK cells. But some leukemia cells without NKG2D ligand or lower expressed can escape the immune surveillance function of NK cells. So how to increase the expression level of NKG2D receptors or ligand may can reverse the immune tolerance to NK cells, and improve immune curative effect. MICA is most closely related with the cytotoxic sensitivity of NK cell in the six NKG2D ligand. This study aims to investigate the mechanism underlying the effects of matrine to enhance the cytotoxic sensitivity of K562and K562/ADM cells to natural killer cells.Methods:The IC50of K562and K562/ADM treated with Matrine for48h was determined with the cck-8assay and this level of Matrine was chosen to treat K562and K562/ADM cells. The expression of MICA ligands on the target cells was determined by flow cytometry, the genes expression of MICA ligands of K562and K562/ADM cells before and after incubation with matrine was determined by RT-PCR. The cytotoxic sensitivity of the K562and K562/ADM cells to NK cells before and after treating with matrine was measured by LDH releasing assay.Results:The expression rates of MICA on the K562and K562/ADM cells incubated with matrine increased from (45.09±4.25)%,(17.03±4.94)%to (59.66±3.43)%,(28.30±8.42)%. respectively. The mRNA expression of MICA on the surface of K562and K562/ADM cells treated with matrine increased to1.53±0.15、2.69±0.40, respectively. At the E:T ratio of5:1、10:1and20:1, the cytotoxic sensitivity of the treated K562and K562/ADM was higher than un-treated cells, showing significant differences in the cytotoxic sensitivity of the target cells in both groups produced by matrine treatment (P<0.05).Conclusion:The different expression of MICA mRNA and protein on the surface of K562and K562/ADM cells is correlated with the cytotoxic sensitivity of NK cell. The matrine could obviously up-regulate the expression of MICA ligands on the surface of K562and K562/ADM cells and enhance the cytotoxicity of NK cell against the K562and K562/ADM cells.