Correlation Between Immune Checkpoint And Microsatellite Instability High Frequency Colon Cancer Based On Bioinformatics Analysis And Clinical Gene Sequencing Verification

Objective:Colon cancer is one of the most common malignant tumors in the world,ra-nking third in incidence but second in mortality.The incidence of microsatellite instability high(MSI-H)frequency colon cancer is only 15%,and its pathogene-sis is still unclear.Exploring the mechanism of MSI-H frequency colon cancer c-an help us find new therapeutic targets and improve the prognosis of patiens.O-ur study mainly analyzes the HUB genes associated with MSI-H frequency colo-n cancer using bioinformatics methods,performs survival analysis,and selects H-UB genes with differential immune checkpoint expression and interaction.Inaddi-tion,we also screen for different major histocompatibility complex(MHC)also k-nown as human leukocyte antigens(HLA)to intervene in the immune checkpoint pathway.Finally,we explore the expression of these HUB genes through high throughput sequencing technology and provide a theoretical basis for the diagnosi-s and treatment of MSI-H frequency colon cancer.Methods:1.We constructed a Cox risk model based on the expression matrix of MSI-H frequency colon cancer-related genes.We divided the MSI-H frequency colon cancer tissue samples from the TCGA database into a training set 70% and a validation set30%.2.We used univariate Cox regression to screen for prognostic genes associated with MSI-H frequency colon cancer,perform risk scores,and then use LASSO Cox regression to construct a prognostic model and analyze the relationship between HUB genes and MSI-H frequency colon cancer prognosis.3.We further screened for immune checkpoint and HLA genes that are differentially expressed in MSI-H frequency colon cancer to provide a theoretical basis for targeted therapy.4.We used high-throughput sequencing experiments to verify the expression of HUB genes in MSI-H frequency colon cancer tissues.Results:1.We divided the samples into low-risk and high-risk groups based on the median of the prognostic risk score.Both the training and validation sets showed that the prognosis of the low-risk group was better than that of the high-risk group.Through LASSO Cox regression analysis,we finally screened for 4 prognostic genes.2.The AUC value of the prognostic genes was greater than 0.5 in both the training and validation sets,indicating the accuracy of the 4 HUB genes used in the MSI-H frequency colon cancer prognostic risk model.3.The immune checkpoint,HLA,and CD44 genes that were screened can also serve as targets for MSI-H frequency colon cancer treatment.4.We screened a total of 887 differentially expressed m RNAs through high-throughput sequencing,with 212 m RNAs upregulated and 675 m RNAs downregulated in MSI-H frequency colon cancer tissues compared to normal colon cancer tissues.5.Combining the differentially expressed genes screened from the TCGA database with the results of high-throughput sequencing of MSI-H frequency colonl cancer blood samples,we found that SORBS2 and DPYD genes were highly expressed in MSI-H frequency colon cancer blood tissues,AGR2 gene was highly expressed in some MSI-H frequency colon cancer blood tissues,and MMP3 gene was not expressed in either the MSI-H frequency colon cancer blood tissues or the normal colon cancer blood tissues.Conclusions:1.The differential genes screened from the TCGA database were screened out by univariate COX regression to screen 13 differential genes,of which 4 were low-risk genes and 9 were high-risk genes.2.Through LASSO COX regression analysis,four prognostic genes,including AGR2,MMP3,SORBS2 and DPYD,were finally established,and the Kaplan-Meier survival curve was plotted,and the AUC value was > 0.5,which further verified the accuracy of our model,and confirmed that the high expression survival time of AGR2,MMP3 and SORBS23 genes in MSI-H frequency colon cancer had a long survival time and a good prognosis.However,3 genes promote tumor occurrence and tumor metastasis.The survival time of DPYD high expression is relatively short and the prognosis is poor,but it can inhibit the occurrence and development of tumors and belongs to a human protective gene.Provides prognostic-related markers for MSI-H frequency colon cancer.3.Differential analysis,further screening of immune checkpoints and HLA that are different from HUB gene,provides a new therapeutic target for MSI-H frequency colon cancer.4.The correlation analysis further elaborated that CD44 has a positive correlation with immune checkpoints.5.A total of 887 differential m RNAs were screened by high-throughput sequencing,of which 212 m RNA expression was upregulated and 675 m RNA expression was downregulated(MSI-H frequency colon cancer tissue compared to ordinary colon cancer).6.Combined with the differential genes screened in the TCGA database and the high-throughput sequencing results of MSI-H frequency colon cancer blood samples,it was concluded that SORBS2 and DPYD genes were highly expressed in MSI-H frequency colon cancer blood tissues.AGR2 gene is highly expressed in some MSI-H frequency colon cancer blood tissues;The MMP3 gene is not expressed in either MSI-H frequency colon cancer blood tissue or common colon cancer blood tissue.7.It is possible to provide new ideas for the diagnosis and treatment of MSI-H colon cancer based on our screening of four HUB genes,immune checkpoints with significant differences with HLA and CD44,and immune checkpoints with relevance to MSI-H colon cancer.