The Role Of DNA Methylation Difference In Lymph Node Metastasis Of Early Gastric Cancer

Objective:According to the latest statistics of GLOBOCAN 2020,gastric cancer has become the most common cancer in the world,and its mortality is also in the forefront of the world.China has become a high incidence rate and high mortality area of gastric cancer in the world.The diagnosis of gastric cancer has increased every year,which seriously threatens the health of the Chinese people and has increased the huge economic burden on the Chinese population.According to the data of China gastrointestinal Federation,the main staging of gastric cancer in China is advanced stage,accounting for 80.3%of all gastric cancer patients.In recent years,with the gradual emphasis on gastric cancer screening in China,the proportion of patients with early gastric cancer is increasing year by year,and the prognosis is relatively good.For patients with early gastric cancer without lymph node metastasis,endoscopic EMR or ESD surgery is feasible on the premise of meeting the indications.This method has the same effect as general gastric cancer surgery for the diagnosis and treatment of patients,and can improve the postoperative life experience of patients,greatly reducing the economic burden and mental pressure of patients.However,for patients with early gastric cancer with lymph node metastasis,endoscopic resection alone is obviously insufficient.For this reason,the prediction of lymph node metastasis of early gastric cancer is an important premise and basis to guide the clinical rational choice of surgical methods.Methods:The samples were collected from the patients who were treated by surgery during hospitalization,and paraffin tissue of pathology department.The patients were diagnosed as early gastric cancer.Then,the data were collected according to the DNA methylation state,and the data were collected according to the final pathological stage of the patients.Then,the genes of the methylation sites were analyzed through the analysis of the relevant data,and the difference map of methylation was established.At the same time,the differences of methylation markers with/without lymph node metastasis in the patients with and without lymph node metastasis were distinguished by DNA methylation detection To explore the methylation status of early gastric cancer gene with/without lymph node metastasis,in order to predict the risk of lymph node metastasis in patients with early gastric cancer by methylation detection.Results:Among 100 cases of early gastric cancer tissues collected,20 cases of lymph node metastasis(LN+)and 80 cases of lymph node non metastasis(LN-)were primary and paracancerous samples.We constructed 100 genome-wide high-throughput(EPIC)databases and DNA SEQ of these samples.Through the sequencing analysis of 20 In+and 80 In-samples,volcano map and methylation were made β P value distribution and P value histogram.From the above results,there are differences in CpG sites between In+and LN-tissue samples.Univariate analysis showed that T stage(P=0.02),vascular nerve invasion(P＝0.023)and Gnas methylation expression(P=0.001)were risk factors for LN + in early gastric cancer.In multivariate analysis,T stage(HR=9.906,95%CI:1.48～60.15,P=0.048),vascular invasion(HR=20.035,95%CI:1.64～240.77,P=0.032)and Gnas(HR=33.620,95%CI:3.25～322.2,P=0.006)were risk factors for positive lymph node metastasis in early gastric cancer,indicating that Gnas,T stage and vascular invasion can all indicate lymph node metastasis in early gastric cancer.Through the survival analysis of tgca database,we found that the high expression of Gnas in early gastric cancer shortens the overall survival of patients,on the contrary,the overall survival of patients increases.This result shows that Gnas exists as a poor prognosis in early gastric cancer.Conclusions;(1)DNA genetic testing based on next-generation sequencing technology(NGS)can distinguish lymph node metastasis from early gastric cancer,and there are differential CpG sites between LN+and LN-;(2)We found that GNAS methylation in gastric cancer tissues showed significant difference in whether lymph node metastasis occurred in early gastric cancer tissues,indicating that there was a significant correlation between GNAS gene and whether lymph node metastasis occurred in early gastric cancer;(3)Univariate and multivariate analysis showed that Gnas was a risk factor for lymph node metastasis of early gastric cancer.Tgca database analysis also revealed that Gnas indicated poor prognosis,indicating that Gnas has a high application value in predicting poor prognosis of early gastric cancer.