Study On The Mechanism Of Myeloid-Derived Suppressor Cells In The Development Of Gastric Cancer

Objective:To investigate the expression of the markers associated with Myeloid-derived suppressor cells,Wnts and?-Catenin in gastric tissues of different lesions,and to explore how MDSC can promote the occurrence of gastric cancer and its correlation with the prognosis of gastric cancer.Method:The first part of the experiment is to divide fresh gastric tissue specimens into three groups:gastric cancer,precancerous lesions and non-atrophic gastritis,with 30patients of each group.The proportion of CD11b(+)Gr-1(+)MDSC in total CD45+leukocytes were tested for in three groups of tissue samples by flow cytometry.The differences of data in each group were analyzed.Then,the expression level of Wnts gene in the sorted MDSC was detected by RT-PCR,and the difference of Wnts expression levels among the three groups was analyzed.In the second part,another 261 tissue specimens were collected,including 79patients in the gastric cancer group,61 patients in the precancerous lesions group,and121 patients in the non-atrophic gastritis group.Three groups of gastric tissue specimens were made into tissue microarrays.The expression of MDSC and?-Catenin was detected by immunohistochemistry through serial sectioning,and the differences were analyzed.At the same time,the 261 subjects were followed up,the survival curve of each group was drawn via Kaplan-Meier method,and the log rank test was used to analyze the effect of MDSC on the prognosis of patients.Result:1 Flow cytometry results showed that the proportion of CD11b(+)Gr-1(+)MDSC in total CD45+WBC in the gastric cancer group(13.11 0.15%)was higher than that in the precancerous lesion group(7.23 0.45%),and the difference between the two groups was statistically significant(P<0.005).In the non-atrophic gastritis group,the proportion(0.62 0.35%)was lower than the expression level in the precancerous lesion group,and the difference between the two groups was statistically significant(P<0.005).2.The results of immunohistochemistry showed that the level of CD15,a related marker of MDSC,was 1628±155/cm~2 in the gastric cancer group,427±33/cm~2 in the precancerous lesion group,5±4/cm~2in the non-atrophic gastritis group.The results of statistical analysis showed that the level of CD15 in the gastric cancer group was significantly higher than that in the precancerous lesion group,the difference was statistically significant(P<0.005);the level of CD15 in the precancerous lesion group was higher than that in the non-atrophic gastritis group,the difference was statistically significant.(P<0.005).3.The results of RT-PCR indicated that Wnt4,Wnt5,Wnt5?and Wnt16 were up-regulated in gastric cancer group,which was higher than Wnts gene expression level in precancerous lesion group(P<0.05).The expression levels of Wnt4,Wnt5,Wnt5?and Wnt16 in precancerous lesion group were significantly higher than those in non-atrophic gastritis group,and the difference was statistically significant(P<0.05).4.The ectopic expression of?-catenin was identified by immunohistochemistry.The ectopic level of?-catenin in gastric cancer group was 81.4±0.98%,and the ectopic level of precancerous lesion was 33.6±0.54%.The ectopic level of non-atrophic gastritis was 0.3±0.04%.The ectopic level of?-catenin in the gastric cancer group was significantly higher than that in the precancerous lesion group,and the difference was statistically significant(P<0.005).In the non-atrophic gastritis group,the cytoplasm or nucleus of glandular cells was not stained,Compared with the precancerous lesion group,the ectopic expression of?-catenin was not obvious,and the difference was statistically significant(P<0.005).5.The survival time of gastric cancer in different patients was compared by Kaplan-Meier method.The results showed that the survival time of patients with poorly differentiated gastric cancer in gastric cancer group was(29.15±9.41)months,the survival time of patients with moderately differentiated gastric cancer(41.79±10.83)months,and the survival of precancerous lesions group.At the time of(54.92±7.41)months,the survival time of the non-atrophic gastritis group was 60months.Using log rank test,the survival time of patients was gradually shortened in non-atrophic gastritis,precancerous lesions and gastric cancer,and the difference was statistically significant(P<0.05).Conclusion:The number of MDSC is gradually increasing in non-atrophic gastritis,precancerous lesions,and gastric cancer.Abnormally accumulated MDSCs in the gastric cancer and up-regulated Wnt signal make?-Catenin express abundantly in the membrane and ectopic to the nucleus,thus promoting the development of gastric cancer and affecting its prognosis.