| BackgroundAs one of the most common gastrointestinal malignant tumors in China,early gastric cancer is easily missed due to its inconspicuous symptoms and gastroscopic features.Many patients are already in advanced stages when they are diagnosed,resulting in poor prognosis.Therefore,early diagnosis is the key to improving the prognosis.Traditional biomarkers such as carcinoembryonic antigen,glycoantigen 724,glycoantigen 199 and glycoantigen 125 and have limited roles in clinical applications due to their low sensitivity and specificity.The rapid development of various sequencing technologies in recent years has made it possible to conduct all-round in-depth studies of diseases from multiple perspectives such as genetic,transcriptional,protein and metabolic levels,but their results still require quantities of clinical studies before they can be applied.Therefore,this study is divided into two parts:firstly,we screened potential gastric cancer biomarkers by transcriptome sequencing,and secondly,we performed preliminary validation of some of the screened biomarkers to assess their feasibility for clinical application.Part Ⅰ:Transcriptomics-based biomarker study of gastric cancerAims:We aim to analyze the differentially expressed genes during gastric carcinogenesis by transcriptome sequencing,analyze the pathways they are involved in,search for potential biomarkers for gastric cancerMethods:Patients with non-atrophic gastritis,intestinal metaplasia and gastric cancer who underwent gastroscopy or surgery in Qilu Hospital,Shandong University from May 2019 to October 2020 were included.Gastric tissue specimens were taken for subsequent transcriptome sequencing,differentially expressed genes were then screened.Functional annotation,GO enrichment analysis,KEGG pathway analysis and protein-protein interaction were performed for the differentially expressed genes.Then luster analysis,GO and KEGG enrichment analysis and protein-protein interaction network analysis were performed for the differentially expressed genes.Results:A total of 30 patients were included.They were divided into 3 groups(NAG,IM and GC),10 cases in each group.A total of 60,612 genes were detected by transcriptome sequencing.There were 6,242 differentially expressed genes between GC group and NAG group,including SERPINEI,ADAMTS4,MARCO,KLK7,BGN,and KLK10 etc.GO enrichment analysis showed that these differential genes were involved in signal transduction,and cell differentiation etc.,and most of them were related to protein binding,metal ion binding etc.KEGG enrichment analysis revealed that the development of gastric cancer may be closely related to cytokine receptor interaction pathway and cell adhesion factor pathway etc.Conclusions:1.genes such as SERPINE1,ADAMTS4,MARCO,KLK7,BGN and KLK10 may be potential biomarkers and therapeutic targets for gastric cancer and need to be further investigated.2.Gastric cancer differential genes are involved in signal transduction,cell differentiation etc.,and most gene functions are related to protein binding,metal ion binding etc.3.The development of gastric cancer may be closely related to cytokine receptor interaction pathway,cell adhesion factor pathway etc.Part Ⅱ:Study of the relationship between KLK7 and KLK10 expression,clinicopathological characteristics and prognosis of gastric cancer patientsAims:To validate the expression of the screened differentially expressed genes KLK7 and KLK10 in gastric cancer and precancerous disease and the relationship with clinicopathological features and prognosis,and to initially screen for biomarkers that can assist in the diagnosis and guide the prognosis of gastric cancer.Methods:Patients with non-atrophic gastritis,chronic atrophic gastritis,intestinal metaplasia,early gastric cancer,and progressive gastric cancer who underwent gastroscopy or surgery in Qilu Hospital of Shandong University from May 2019 to October 2020 were included.Gastric tissue specimens were retained for immunohistochemical staining and analysis.The expression of the screened differentially expressed genes KLK7 and KLK10 in gastric cancer was verified by Oncomine database,and then by immunohistochemistry.The relationship between their expression and patients’ gender,age,gastric cancer size,differentiation,depth of infiltration,etc.was analyzed.The relationship between expression and prognosis was analyzed by Kaplan-Meier Plotter database.Results:1.Information of included patients:74 patients were included in this study,including 17 cases of gastritis,15 cases of atrophy,13 cases of intestinal metaplasia,16 cases of early gastric cancer,and 13 cases of progressive gastric cancer.2.Expression of KLK7 and KLK10 in Oncomine database:KLK7 and KLK10 were hardly expressed in normal gastric tissues,but significantly elevated in gastric cancer(P<0.001)3.Immunohistochemical analysis of KLK7 and KLK10 expression:KLK7 was mainly expressed in the cell membrane and KLK10 was mainly expressed in the cytoplasm;Their expression were both significantly higher in gastric cancer tissues(P<0.05).4.Relationship between expression and clinicopathological characteristics:KLK7 expression was correlated with the degree of differentiation and depth of infiltration of gastric cancer in patients,but not with patient’s gender,age,size of gastric cancer,lymph node metastasis and TNM stage;KLK10 was not correlated with patient’s gender,age,size of gastric cancer etc.5.Expression and prognosis:the overall survival rate of patients with high KLK7 and KLK10 expression was lower than patients with low expression(P<0.05).Conclusions:1.the expression of KLK7 and KLK10 was significantly higher in gastric cancer,which can be used to assist in the diagnosis of gastric cancer.2.KLK7 expression correlated with the degree of differentiation and depth of infiltration of gastric cancer in patients,while there was no significant correlation between KLK10 and pathological features of patients.3.High expression of KLK7 and KLK10 was correlated with poor prognosis of gastric cancer. |
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