Experimental Study On Effects Of Kaempferol Against Gastric Cancer And Its Regulation Of Dendritic Cell Activities

BackgroundGastric cancer is one of the most common malignancy with high mortality in the world. Recently, Traditional Chinese medicine on anti-tumor research has become a research focus at home and abroad.Rencent research shows that flavonoids can effectively inhibit the development of tumor.The anti-tumor studies of Scutellaria barbata have been discussed by Chinese and Western integrative medicine laboratory in our school for many years.They show that these active ingredients of Scutellaria barbata can suppress tumor growth through a variety of mechanisms.We selected one active ingredient of Scutellaria barbata, kaempferol, as the object of this study.It has been reported that kaempferol could inhibit proliferation and induce apoptosis of tumor cells.But kaempferol in gastric cancer research is rare..Objective1To identify whether kaempferol can inhibit proliferation and induce apoptosis in human gastric cancer cell line SGC-7901in vitro, and investigate its mechanism preliminary;2To investigate whether kaempferol can regulate the function of dendritic cells derived from peripheral blood mononucleated cells of patients with gastric cancer.Methods1The cell proliferation was tested by MTT assay.Flow cytometry was used to detect the cell apoptosis, the mechanisms of apoptosis and MHC Class I chain-related protein A (MICA) expressions. Expression and secretion of vascular endothelial cell growth factor (VEGF) was measured by immunofluorescence assay and enzyme-linked immunosorbent assay (ELISA), respectively.2Peripheral blood mononuclear cells (PBMC) were isolated from the fresh blood of patients with gastric cancer by lymphocyte separation medium (Ficoll), and than induced into dendritic cells (DCs) with GM-CSF and IL-4.3Flow cytometry was used to evaluate the expression of HLA-DR and CD86molecules on DCs and the impact of the phagocytic activity of immature DC (iDC).Results 1Kaempferol inhibited proliferation of SGC-7901cells:Compared with the control group of solvent, different concentrations of kaempferol can observably inhibit the proliferation of SGC-7901cells (P<0.05),with dose and time dependent (P<0.05).2Kaempferol induced apoptosis of SGC-7901cells:Treated with60μg/ml and180μg/ml of kaempferol for12hours,the apoptosis rate of SGC-7901was significantly higher than the solvent control group, in a dose-dependent manner (P<0.05).3Kaempferol increased the level of reactive oxygen species (ROS) in SGC-7901cells: After kaempferol (20,40,80μg/ml) acting on SGC-7901cells for24hours,intracellular ROS level was increased in a dose-dependent manner, as compared with the solvent control group (P<0.05).4Kaempferol suppressed the secretion and the expression of VEGF of SGC-7901cells: Kaempferol inhibited the VEGF secretion of gastric cancer cells(P<0.05). Immunofluorescence assay results showed that intracellular expression of VEGF level was also reduced with stimulation of kaempferol dose-dependently.5Kaempferol down-regulated the expression of MICA on SGC-7901cells:Compared with the negative group, the expression of MICA was decreased with culture of kaempferol (P<0.05).6Kaempferol inhibited the maturation of DCs:Kaempferol down-regulated the expression of HLA-DR and CD86molecules on DCs, compared with the negative group (P<0.05), In addition, kaempferol suppressed LPS-stimulated DC maturarion (P <0.05).7SGC-7901cells treated with kaempferol increased the phagocytic activity of iDCs: iDCs which were co-cultured with SGC-7901cells treated with kaempferol for12hours, could swallow much more easily than the negative group. The higher concentration of drug effecting on cells, the stronger was phagocytic activity of DC (P<0.05).Conclusion1Kaempferol has effects of anti-proliferation and apoptosis-promoting on the gastric cancer cell line.The mechanism may be related to enhancing the level of intracellular ROS release.2Kaempferol suppresses the secretion and the expression of VEGF of SGC-7901cells.It also down-regulates the expression of MICA of SGC-7901cells. 3Kaempferol down-regulates maturation of DCs induced from PBMC.However, SGC-7901cells treated with kaempferol are easier to be swallowed up by the immature DCs.