| Gastric cancer is one of the most common malignant tumors in the world.About8% of all tumor deaths are attributed to gastric cancer.In the course of chemotherapy for advanced gastric cancer,there are many cases of tumor resistance,which is mostly related to the high heterogeneity of gastric cancer,that is,gastric cancer is a collection of different molecular entities,rather than a single homogeneous disease.Therefore,we urgently need to study the heterogeneity of gastric cancer to solve the problem of heterogeneity in the diagnosis and treatment of gastric cancer.In this study,we will use whole exome sequencing(WES)to explore the tumor heterogeneity of gastric cancer,and provide the basis for the diagnosis and treatment of gastric cancer,and for finding more molecular targets of gastric cancer.Objective:We used WES to study the gene mutation of different sites and metastasis of gastric cancer to explore the heterogeneity of it.Method:According to the inclusion and exclusion criteria,two samples of gastric cancer were selected,sampling in the center and 3,6,9,12 o’clock as well as the metastasis,frozen in liquid nitrogen tank and then kept in the refrigerator at-80 ℃.Using Agilent SureSureSelectHumanAll Exon V5 kit to capture exons from genomic DNA,and then using HiSeq PE150 mode(two terminal sequencing)to sequence and analyze the whole exon,using speedseq to compare and search for mutations,single nucleotide polymorphism(SNP)analysis and gene copy number analysis,and then comparing the Catalogue Of Somatic Mutations In Cancer(COSMIC),analyze the consequences of SNP: synonymous mutation;non synonymous mutation;stop codon mutation;then draw the SNP mutation heat map of 12 points of two groups of data,and count thenumber of mutation genes;screen out the targeted gene mutation points by comparing the results with The Drug Gene Interaction Database(DGIdb).Finally,the heterogeneity analysis of the selected data was used to guide the selection of sequencing samples in clinical practice.Result:1.In SNP,the change of C: G → T:A base is the most common;the most common consequence of SNP mutation is synonymous mutation and non synonymous mutation,synonymous mutation is slightly more than non synonymous mutation;In the two group,the non-trunk mutation accounts for 12.6% and 17.9% respectively;the overlap rate of private mutation is 0%,the overlap rate of trunk mutation is 50.2% and59.0%,and the overlap rate of branch mutation is 33.3% and 22.6% respectively.2.After the SNPs of the two groups were screened in the COSMIC and DGIdb,they shared 15 major mutations:NOTCH2、TP53、ALK、MSH6、SETD2、GATA2、APC、HLA-DRB5、HLA-DRB1、EGFR、PRSS1、MTAP、PTCH1、ORM1、CACNA1B;3.When the number of random samples of primary gastric cancer was 2,the maximum and minimum of targeted non-trunk mutations were 100% and 75% in the first group,and 100% and 43% in the second group;When the number of random samples of primary and metastatic gastric cancer was 2,the maximum and minimum of targeted non-trunk mutations were 100% and75% in the first group,and 100% and 43% in the second group;Conclusion:1.Gastric cancer has high intratumor and interpatient heterogeneity;2.NOTCH2、TP53、ALK、MSH6、SETD2、GATA2、APC、HLA-DRB5、HLA-DRB1、EGFR、PRSS1、MTAP、PTCH1、ORM1、CACNA1B,these 15 mutations may be potential therapeutic targets of gastric antrum pyloric tumors for further study,which exist targeted drugs;3.In order to obtain gene mutation of gastric cancer patients for molecular targeted therapy,2-point sampling or 3-point sampling is an economic and effective sampling method;... |
