The RASSF1A,RUNX3 DNA Methylation Status Of Tumor Tissues/Serum Circulating Tumor DNA And It’s Consistency Analysis In Gastric Cancer

Objective: Gastric cancer(GC)is one of the common malignant tumors.It ranks second in malignant tumors in China.Although the incidence of gastric cancer is decreasing year by year,the 5-year survival rate is only 35.9%.Therefore,early diagnosis,early treatment and efficacy evaluation of gastric cancer are still urgent problems to be solved.Epigenetic changes can lead to abnormal changes in gene function and malignant transformation of cells.Recent research shows that abnormal DNA methylation in the promoter region of genes leads to the inactivation of tumor suppressor genes and related genes in cells,and is a clear epigenetic marker in gastric cancer.There have been many reports of methylation of gastric cancer genes,and methylation of specific genes has been used as a target for detecting and diagnosing biopsy specimens and non-invasive body fluids such as serum.At the same time,circulating tumor DNA(ct DNA)is present in peripheral blood of patients with malignant tumors,and ct DNA has tumor-specific genetic information.Quantitative and qualitative methods to detect changes in circulating DNA of related tumor genes may provide patients with full real-time information.RASSF1A(ras-association domain family 1A)and RUNX3(RUNX-related transcription factor 3)are important tumor suppressor genes involved in the pathogenesis of gastric cancer.In this study,RASSF1 A and RUNX-related transcription factor 3 genes were found in circulating tumor DNA and gastric cancer tissues and control tissues of gastric cancer patients.The DNA methylation status of the promoter region was detected,and the consistency was analyzed.The sensitivity and specific new tumor markers were explored for the diagnosis of gastric cancer and high-risk population screening.Methods:We collected gastric cancer cases treated by gastrointestinal surgery in the First Hospital of Jilin University from January 2018 to January 2019.After informed consent of patients and their families,patients were given peripheral venous blood within one week before surgery,and gastric cancer was collected after surgery.Tissue and control mucosal tissue(5 cm or more from the edge of the tumor).Extract the corresponding tissue DNA and convert the extracted DNA using sulfite,and RASSF1 A and RUNX3 were amplified by methylation-specific quantitative PCR(MS-q PCR).Then,the results of DNA electrophoresis were analyzed to compare the methylation rates between different tissues,and the consistency of ct DNA in blood samples and DNA methylation status in tumor tissues was compared.The corresponding sensitivity and specificity were analyzed to determine the relationship between DNA methylation of RASSF1 A and RUNX3 in patients’ blood,tumor tissues and adjacent tissues.Finally,we analyzed the correlation between the methylation status of RASSF1 A and RUNX3 genes and the pathological stage of gastric cancer and tumor differentiation was analyzed.Results:(1)The DNA methylation rates of RASSF1 A gene promoter region in GC tissues and control tissues were 73.3%(22/30)and 16.7%(5/30);the DNA methylation rate of RUNX3 gene were 80.0%(24/30)and 13.3%(4/30).The DNA methylation detection rates of RASSF1 A and RUNX3 genes were significantly higher in gastric cancer tissues than in control control tissues(P < 0.001;P < 0.001).(2)The comparison of p TNM staging in patients with GC showed that the incidence of RASSF1 A methylation was in stage I,42.9%(3/7),66.7%(6/9)and 92.9% in stage II and III gastric cancer,respectively./14);The incidence of RUNX3 methylation was 42.9%(3/7),88.9%(8/9)and 92.9%(13/14)in stage I,stage II and stage III gastric cancer,respectively,in stage II At the stage III and stage III,the DNA methylation rate of RASSF1 A and RUNX3 in gastric cancer was significantly higher than that in stage I gastric cancer(P<0.05).In patients with methylation in the RASSF1 A and RUNX3 gene-driven promoter regions,DNA methylation levels were found to be closely related to tumor vascular invasion,neural invasion,and TNM staging.(3)The detection rates of RASSF1 A and RUNX3 methylation in peripheral blood ct DNA of gastric cancer patients were 70.0%(21/30)and 73.3%(22/30).The consistency of RASSF1 A and RUNX3 methylation in blood samples and tissue samples were 90.0% and 86.7%.The sensitivity of RASSF1 A and RUNX3 methylation in blood ct DNA were 90.9% and 87.5%,and the specificity of RASSF1 A and RUNX3 methylation detection were 87.5% and 83.3%.Conclusion:(1)The methylation of RASSF1 A and RUNX3 gene promoter regions was significantly higher in gastric cancer tissues than in normal control gastric tissues,and there was a significant correlation with the incidence of gastric cancer.(2)The relatively late TNM stage of gastric cancer was significantly associated with the high methylation rate of the RASSF1 A and RUNX3 gene promoter regions.At the same time,it was found that there was a significant correlation between DNA methylation positive of RASSF1 A and RUNX3 gene and tumor vascular invasion.There was a correlation between DNA methylation positive of RASSF1 A gene and neural invasion.Both methylation of genes were independent of the degree of tumor pathological differentiation.(3)Peripheral blood ct DNA is highly consistent with the methylation status of RASSF1 A and RUNX3 promoters in GC tissues.The ct DNA methylation status can accurately reflect the DNA methylation status of the corresponding gastric cancer tissues.(4)The RUNX3 and RASSF1 A methylation detection of blood sample ct DNA has high sensitivity and good specificity,which may become one of the tumor markers for the diagnosis of gastric cancer.It can be used as a potential non-invasive diagnostic combination index in gastric cancer blood,and it will have a good application prospect.