Effect Of Tumor-associated Fibroblasts （TAF）on PD-L1 Expression In MNK45 And SGC7901

Research background Gastric cancer is one of the world’s most common digestive system malignant tumor, especially in the east Asian countries such as South Korea, Japan and China, the morbidity and mortality of gastric cancer are ranked first in northwest region of china. Tumor cells can escape from the immune surveillance. Previous studies have focused on the changes of tumor cells in immune escape, and little is known about the effect of tumor microenvironment(TME) on immune escape. TAF is an important part of the TME, it is different from the normal fibroblasts,has special physiological and biochemical characteristics, TAF can inhibit the function of immune cells, but the specific mechanism has not been clarified. CD8 + T cells play significance role in tumor immunity, there is a kinds of molecules in T cell membrane playing negative regulatory role,named co-inhibition molecules. The main co-inhibition molecules include CTLA-4 and PD-1.PD-1 in a variety of cells surface, when PD-1 meet their corresponding ligand PD-L1, is activated,activated PD-1 inhibit kinase activity of T cells. Aim of this study was to investigate the effect of TAF on the expression of PD-L1 in gastric cancer cells.Method Take gastric cancer cell lines MNK45, SGC7901 non-contact co-culturing with TAF via trans well 48 hour as experiment group. Take single MNK45, SGC7901 cells as control group, and the two groups were in the same culture condition. The number of MNK45,SGC7901 were counted by microscope in two groups. FCM detection PD-L1 protein expression rate in two groups. PCR detection PD-L1 mRNA level in two groups. The differences of PD-L1 expression between the two groups were compared by T test.Result The number of gastric cancer cells in the experiment group was more than the control group, the expression rate of PD-L1 protein and the mRNA level in the experiment group were higher than that in control group, there were statistical differences between the two groups.Conclusion TAF promote the growth in gastric cancer cell lines MNK45, SGC7901,increase the expression of PD- L1 in MNK45, SGC7901 cells.