Study On The Related Mechanism Of CD4 And CD8 Double Negative T Cells In The Treatment Of Pancreatic Cancer

Objective To study the toxic effects of CD4 and CD8 double negative T cells(DNT cells)on pancreatic cancer cells and whether the DNAM-1(CD226)/CD155 signaling pathway is involved in the killing of pancreatic cancer,and the expression of CD155protein in pancreatic ductal adenocarcinoma tissue is analyzed,and it provides ideas for the possibility of double negative T cells in the clinical treatment of pancreatic cancer patients.Method The antibody adsorption method was used to purify and expand the double negative T cells in the blood of healthy people.In vitro,the CCK-8 method was used to study the killing effect of double negative T cells on pancreatic cancer cells,the human recombinant protein blocking experiment was used to study the toxicity mechanism of DNT cells on pancreatic cancer cells,and the TUNEL method was used to detect the apoptosis of pancreatic cancer cells.A nude mouse model of pancreatic cancer was established,and the nude mice were divided into DNT cell treatment group,gemcitabine treatment group and blank control group to study the killing mechanism of double negative T cells on pancreatic cancer cells in vivo.The expression of CD155protein in pancreatic ductal adenocarcinoma was detected by immunohistochemistry,and the relationship between CD155 protein and clinicopathological characteristics of patients with pancreatic cancer was analyzed.Results The double-negative T cells in the peripheral blood were effectively expanded by the antibody adsorption method and the cell purity reached 96.4%after culture.This study shows that in the in vitro co-culture experiment,double negative T cells can inhibit the growth of pancreatic cancer cells(P=0.0005),and after double negative T cells are co-cultured with pancreatic cancer cells,the expression of related proteins CD155,granzyme B and perforin in DNAM-1/CD155 signaling pathway is increased in pancreatic cancer cells.When double negative T cells were pretreated with DNAM-1receptor blocker DX11,the toxicity of DNT cells to pancreatic cancer cells was reduced,and the expressions of its related proteins CD155,granzyme B and perforin decreased,compared with those without DX11 treatment,there is a significant difference(P=0.037).In the in vivo experiment of pancreatic cancer in nude mice,the results of this experiment showed that the volume and weight of the tumor in the blank control group were higher than double negative T cell group and the gemcitabine group,and the difference was statistically significant(P<0.01),but there was no significant difference between the two treatment groups in tumor weight and volume.The expression of DNAM-1/CD155 pathway-related proteins CD155,granzyme B and perforin in the tumors of the DNT cell treatment group and gemcitabine treatment group were increased compared with the blank control group.The results of immunohistochemistry experiments showed that the expression of CD155 protein in pancreatic ductal adenocarcinoma tissue was higher than that in adjacent tissues,and the difference was statistically significant(χ~2=13.60,P<0.01),and the expression of CD155 protein is related to the degree of differentiation of pancreatic ductal adenocarcinoma(P<0.001),nerve infiltration(P<0.001),and lymph node metastasis(P=0.001).Conclusion Double negative T cells have a killing effect on pancreatic cancer cells and can inhibit the growth of pancreatic cancer cells,and the DNAM-1/CD155 signaling pathway may be involved in the toxicity of pancreatic cancer cells.We have found that the expression of CD155 protein in pancreatic ductal adenocarcinoma tissue is higher than that in normal adjacent tissues,and the increase in CD155 protein expression is related to the degree of differentiation,nerve infiltration and lymph node metastasis of pancreatic ductal adenocarcinoma.