The Effect Of CBX7 On The Biological Function Of Esophageal Squamous Cell Carcinoma And Its Mechanism

Part 1 Expression of CBX7 in ESCC tumor and its clinicalsignificance Purpose: To study the expression level of CBX7 in ESCC tumor and adjuvant tissues,and investigate the association between the protein expression level and clinicopathologic characteristics.Methods: The tissue specimens were purchased from Shanghai Microbiology Technology Co.,Ltd.and included 100 cases of surgically removed esophageal squamous carcinoma(I-III)tissue and 79 cases of peripheral cancer tissue.The expression of each point CBX7 protein was detected by immunohistochemical method.The difference of positive expression rate of CBX7 protein in esophageal squamous carcinoma tissue and its adjacent tissue was analyzed.The software SPSS 22.0 was used to analyze the positive expression rate.Results: The positive expression of CBX7 in 100 patients with esophageal squamous carcinoma was 78,the negative expression group was 22.In 79 cases of peripheral cancer tissue,the positive expression of CBX7 was 77 and the negative expression group was 2.The positive expression rate of CBX7 was 78 % in esophageal squamous carcinoma and 97.5 % in peripheral carcinoma.There was a significant difference between the two groups(P<0.001).Conclusion: The expression of CBX7 protein in human esophageal squamous carcinoma tissue is unusually low,and it may participate in the development and malignant evolution of esophageal squamous carcinoma.Part 2 The biological role and mechanism of CBX7 in ESCCPurpose: To establish CBX7-overexpressed and knockdown ESCC cell lines and investigate the role of CBX7 in proliferation,migration,cell cycle,cell apoptosis and tumorigenicity of ESCC.Moreover,to explore the underlying mechanism involved in CBX7 induced apoptosis.Methods:1.Lentivirus was used to establish CBX7 overexpressed cell lines.We use transient small interference RNA to knock down the CBX7 level in the ECA109 and TE13 cell lines.Western-blot was used to check the expression of CBX7.2.CCK8,EDU and Cell Cloning Formation Experiment clone were used to detect proliferation.Transwell assay without Martigel was used to detect immigration.3.We use flow cytometry analysis to detect cell apoptosis and cell cycle.Then,Western blot was performed to test the expression of Bcl-2,Bax,and Caspase-3 in different cell lines.4.Xenograft tumor model was constructed by subcutaneous injection of TE13 cells,then we further observed the role of CBX7 in tumorigenesis.Results:1.We successfully constructed the CBX7 over-expression ECA109 cells(ECA109 Lenti-CBX7)and the overexpression control ECA109 cells(ECA109 Lenti-ctrl),CBX7 knockdown ECA109 cells(ECA109 si-CBX7)and knockdown control(ECA109 si-ctrl).We also successfully constructed the CBX7 over-expression TE13 cells(TE13 Lenti-CBX7)and the overexpression control TE13 cells(TE13 Lenti-ctrl),CBX7 knockdown TE13 cells(TE13 si-CBX7)and knockdown control(TE13 si-ctrl).2.The proliferation rate was significantly decreased in CBX7 overexpressing cells compared with cells in empty(P<0.05).The transwell assays without Matrigel indicated that lower levels of CBX7 expression correlated with faster migration rates(P<0.05),and that higher levels of CBX7 expression with lower migration rates.3.CBX7 can significantly promote apoptosis.Analysis of WESETERN BLOT showed that CBX7 can promote the decrease of anti-apoptosis protein Bcl-2,and increase the expression of apoptosis protein Bax and cleaved caspase-3.The effects of CBX7 on cell cycle were not statistically significant.4.Over-expression of CBX7 and their effects on tumor growth was also confirmed in xenografts.Conclusion: CBX7 plays a role in the proliferation,migration,apoptosis of ESCC.CBX7 is a tumor suppressor of ESCC.