Study On The Methylation Of SPG20 Gene In Esophageal Adenocarcinoma

Objective: Adenocarcinoma of esophagogastric junction is a serious hazard to human health of malignant tumor of digestive tract,With the development of tumor molecular biology, from the molecular level to cancer research has become a research focus. In recent years, the scholars have also done a lot of research on the molecular mechanism of adenocarcinoma of esophagogastric junction ’s occurrence and development.Spastic paraplegia gene type 20 located on chromosome 13q13.3, which can encode Spartin protein. When SPG20 took methylation,gene expression silence. It also can make the protein expression, cell growth and differentiation regulation arrhythmia. And eventually lead to the occurrence of cancer. The HER-2/neu oncogene, a member of the epidermal growth factor receptor or erb gene family. The gene is located on chromosome 17q21, which encode is transmembrane protein(p185). The protein has tyrosine activity.The protein and the ligand binds together.Through the signal transduction between cells,changed the growth, differentiation and proliferation of cells.Recen- tly, domestic and foreign scholars keen to study the anticancer therapy which using HER2 gene as a target.The study on detection of the methylation status of SPG20 gene and HER2 gene amplification level in adenocarcinoma of esophagogastric junction.Discussion on the methylation of SPG20 gene and HER2 gene amplification in the relationship between the occurrence and development of adenocarcinoma of esophagogastric junction. And it provides new theory and basis for the pathogenesis and targeted therapy of adenocarcinoma of esophagogastric junction.Methods:1 To collect fresh tissues of patients underwent surgery with adenocarcinoma of esophagogastric junction and tissues far from cancer in No.4 Hospital of Hebei Medical University from December, 2013 to August, 2014.2 Detection of SPG20 using pyrosequencing promoter methyl- ation levels in 63 cases of adenocarcinoma of esophagogastric junction and tissues far from cancer.3 The application of fluorescence in situ hybridization(FISH) assay for detection of HER2 gene amplification condition in 63 cases of adenocarcinoma of esophagogastric junction and tissues far from cancer.4 The research data will be processed through SPSSl7.0 statistical software, and apply X2 test and Fisher’S exact test.The test results to P<0.05 was considered statistically significant;When the comparison between the any two groups in three groups, the test results to P<0.0125 was considered statistically significant.Results: 1 The results of Pyrosequencing(Fig.1-Fig.4) 1.1 Hypermethylation of SPG20 gene in adenocarcinoma of esophagogastric junction and tissues far from cancer were respectively 71.43%(45/63) and 14.29%(9/63).The hypermethylation rate of SPG20 gene in adenocarcinoma of esophagogastric junction was significantly higher than that in tissues far from cancer(P<0.01)(Table 1). 1.2 The relationship between SPG20 gene hypermethylation in adenocarcinoma of esophagogastric junction and clinicopathological features(Table 2) 1.2.1 The SPG20 genemethylation rates of the group with lymph node metastasis and lymph node metastasis group were 82.93%(34/41) and 50%(11/22).Lymph node metastasis group SPG20 gene hypermethylat- ion rate was significantly higher than the group without lymph node metastasis(P<0.05). 1.2.2 The SPG20 gene high methylation rates in the TNM staging of group I, II, III were 40%(2/5),57.69%(15/26), 87.50%(28/32);There was a statistically significant difference between stage II and III(P < 0.0125); Other groups had no statistical significance(P>0.0125). 1.2.3 SPG20 gene methylation rate in low differentiation group, middle differentiation group, high differentiation group of adenocarcinoma of esophagogastric junction were 90.63%(29/32),68.18%(15/22),11.11%(1/9);There was a statistically significant difference between middle differentiation group and high differentiation group(P < 0.0125); there was a statistically significant difference between the low differentiation group and high differentiation group(P < 0.0125); No statistically significant differences between the low differentiation group and middle differentiation group(P > 0.0125). 1.2.4 The gender and age of patients with adenocarcinoma of esophagogastric junction has no significant with the high level of methylation of SPG20 gene(P>0.05). 2 The results of fluorescence in situ hybridization(Fig.5-Fig.8) 2.1 The positive rate of HER2 amplification in adenocarcinoma of esophagogastric junction gene was 26.98%(17/63), and tissues far from cancer was not found the HER2 gene amplification. 2.2 The relationship between HER2 amplification in adenocarcinoma of esophagogastric junction and clinicopathological features(Table 3) 2.2.1 The positive rate of HER2 amplification of the group with lymph node metastasis and lymph node metastasis group were 36.59%(15/41)and 9.09%(2/22).Lymph node metastasis group the positive rate of HER2 amplification was significantly higher than the group without lymph node metastasis(P<0.05). 2.2.2 The positive rate of HER2 amplification in the TNM staging of group I, II, III were 20.00%(1/5),7.69%(2/26),43.75%(14/32);There was a statistically significant difference between stage II and III(P < 0.0125); Other groups had no statistical significance(P>0.0125). 2.2.3 The gender and age of patients with adenocarcinoma of esophagogastric junction has no significant with the positive rate of HER2 amplification(P>0.05). 3 The correlation between methylation of SPG20 gene and HER2 gene amplification in adenocarcinoma of esophagogastric junction: The positive rate of HER2 gene amplification in SPG20 gene hypermethylation tissues was 35.56%(16/ 45),the positive rate of HER2 gene amplification in SPG20 gene hypomethylation tissues was 5.56%( 1/18),the difference was statistically signifycant(P<0.05)(Table 4).Conclusion:1 The hypermethylation rate of SPG20 gene in adenocarcinoma of esophagogastric junction was significantly higher than the tissues far from cancer, suggesting that hypermethylation of SPG20 gene may be related to carcinogenesis and development of adenocarcinoma of esophagogastric junction.2 Hypermethylation of SPG20 gene may be related with pathological staging of adenocarcinoma of esophagogastric junction, the degree of differentiation and Lymph node metastasis.It is suggested that SPG20 gene hypermethylation is related to the degree of progress of the adenocarcinoma of esophagogastric junction.3 Amplification of HER2 gene exists in adenocarcinoma of esophagogastric junction tissues, Tissues far from cancer have no HER2 gene amplification, suggesting that HER2 gene amplification may be associated with theincidence of adenocarcinoma of esophagogastric junction.4 The HER2 amplification may be related with pathological staging of adenocarcinoma of esophagogastric junction, the degree of differentiation and Lymph node metastasis.It is suggested that HER2 gene amplification is related to the degree of progress of the adenocarcinoma of esophagogastric junction.