Clinicopathological Features And The Mechanism Of TOX3 In Chinese Familial Gastric Cancer

Objectives:1.To study the genetic characteristics of familial gastric cancer(FGC)in China and to analyze its clinicopathological features.2.To study the effect of TOX3 on the biological behavior of gastric cancer cells and to analyze the correlation between TOX3 and the pathological grade of gastric cancer,and to provide evidences for early screening,genetic risk assessment and clinical guidance of Chinese patients with familial gastric cancer and family members.Methods:1.The pathological data of 20 pedigrees that fulfilled the screen criteria of FGC recommended by ICG-HCG have been collected and the family trees have been drawed.Medical data of 620 patients with sporadic gastric cancer(SGC)treated in the Department of Surgery,Zhong Shan Hospital,Xiamen University,between January 2011 and July 2016,were analyzed retrospectively.Gender,age,location of the tumor,histological type and family history of malignant tumor were recorded and analyzed.The different clinico-pathological-features between FGC and SGC were fully analyzed.2.To study the role of TOX3 in the development and progression of gastric cancer at the molecular level,cell level and tissue level.Western blot and Real-time PCR were used to detect the expression of TOX3 in gastric cancer cells and immortalized cells of gastric mucosa.The effect of TOX3 on the proliferation and migration of gastric cancer cells and the correlation with the clinicopathological features of FGC were studied by cloning assay,transwell experiment and wound healing test by constructing TOX3 stable knockdown cell line MGC803-shTOX3,respectively.Immunohistochemical(IHC)technique was performed to detect the expression of TOX3 in gastric cancer and adjacent normal tissues,and the correlation between protein expression and histopathological grade was analyzed.Results:1.There are 226 family members investigated in 20 pedigrees,including 76 patients with gastric cancer and 151 immediate relatives or mates.Data shown that,the proportion of cardiac gastric cancer in FGC was significantly higher as compared to SGC patients,while the proportion of gastric antrum cancer was significant lower than SGC patients.(82%vs 32.7%,13.1%vs 56%,P?0.0001).The proportion of adenocarcinoma and mucinous adenocarcinoma was 75.4%and 23%respectively for FGC patients and 87.3%and 11.1%for SGC patients,and the differences were statistically significant(P=0.026).Proportion of FGC patients with poor differentiation was significantly higher as compared to SGC patients.(83.6%vs 66.6%,P=0.023).There were no statistically significant differences in the gender,age of onset and clinical stage between FGC and SGC(P>0.05).2.Western blot and Real-time PCR showed that TOX3 expression in gastric cancer cells was much lower than that in gastric mucosa immortalized gastric mucosal cells.The results of clonal formation showed that the proliferation of MGC803 gastric cancer cell line was enhanced after TOX3 knockdown.The migration ability of MGC803 cell line was significantly enhanced after TOX3 knockdown compared with the control group,by transwell experiment and wound healing test.The expression of TOX3 in gastric cancer and adjacent normal tissues was detected by IHC.The expression of TOX3 in gastric cancer tissues was lower than that in adjacent normal tissues,which was positively correlated with the pathological grade of gastric cancer.Conclusion:1.Compared with SGC,the location of tumor in FGC was common proximal,especially in the cardiac area.The histological type in FGC was mainly adenocarcinoma,but mucinous adenocarcinoma increased gradually and the differentiation is poor.Family members of the FGC can through genetic risk assessment and take physical examination regularly to find early gastric cancer and improve the quality of life.2.Based on the results of molecular and cell level experiments,it can be deduced that TOX3 plays a role of tumor suppressor gene in the development of gastric cancer.3.According to the results of exon sequencing analysis,it is suggested that TOX3 is a susceptible gene for familial gastric cancer.The molecular and cellular biology experiments of this study further confirmed that TOX3 is a suspected gene of familial gastric cancer,and its specific mechanism need to further confirmed.