Bioinformatics Screening Of Core Genes In Colon Cancer And Study On The Mechanism Of Dpep1 Promoting Colon Cancer Cell Proliferation

Background:Colorectal cancer is a common digestive system tumor,and its global incidence ranks third,and mortality ranks second.Since colon cancer has no obvious specific clinical symptoms in the early stage and lacks molecular markers for early diagnosis,most patients have already entered the middle and advanced stage when they are diagnosed.With the improvement of the public tumor database,more and more researchers are mining the key molecules that affect the occurrence and development of tumors using bioinformatics analysis.This study aimed to screen out the core genes that affect the occurrence and development of colon cancer through bioinformatics methods;among the core genes,the DPEP1 gene with significantly high expression in colon cancer tissue was selected,and clinical tissue samples were used to verify the expression level of DPEP1 in colon cancer tissue and adjacent normal tissue,and the correlation between its expression level and clinicopathological factors was analyzed;then,DPEP1 and ASCL2 with the highest correlation among the core genes were selected to explore their regulatory mechanism in colon cancer cells and to clarify the role of DPEP1 in colon cancer cell proliferation and chemotherapeutic drug resistance.Methods:1.Three datasets,GSE23878,GSE37182,and GSE74602,were downloaded from the GEO database.R language was used to perform differential expression analysis,weighted gene co-expression network analysis,and Venn analysis to screen out colon cancer core genes.The GO enrichment analysis and KEGG signaling pathway analysis of the core genes were carried out using the R language;expression level validation and Pearson correlation analysis of core genes were performed using the colon cancer dataset in the TCGA database.2.The m RNA level of DPEP1 in 144 cases of colon cancer tissues was detected by the quantitative reverse transcription polymerase chain reaction method.According to the median value,they were divided into high and low expression groups.Combined with the collected clinicopathological data of patients,the correlation between the expression level of DPEP1 and the clinicopathological characteristics of colon cancer patients was analyzed.3.The expression levels of DPEP1 and ASCL2 in colon cancer tissues and adjacent normal tissues were analyzed by immunohistochemical staining and western blotting;the effect of DPEP1 on the expression levels of ASCL2 in colon cancer cells was analyzed by ASCL2 protein stabilization and degradation experiments;The impact of ASCL2 on the expression level of DPEP1 in colon cancer cells was analyzed by western blotting,q RT-PCR,and dual-luciferase reporter gene assay.4.Western blot was used to analyze the effect of DPEP1 on the expression levels of stemness-related molecules;an MTT dosing experiment was used to analyze the impact of DPEP1 on the drug resistance of colon cancer cells.5.The effect of DPEP1 on colon cancer cell proliferation was analyzed by MTT and clone formation assays;the impact of DPEP1 on tumor growth was analyzed by a subcutaneous tumorigenesis model of nude mice.Results:1.From the three datasets GSE23878,GSE37182,and GSE74602,89 shared differentially expressed genes and 90 shared modular genes closely related to tumor phenotypes were obtained,and 11 colon cancer core genes(STC2,TRIP13,TESC,SLC7A5,TPX2,ARID3 A,ASCL2,NKD2,GPT2,DPEP1,and MMP3)were screened out.Among them,DPEP1 was a significantly differentially expressed gene in colon cancer tissues and had the highest correlation with ASCL2(R=0.6).2.The difference in DPEP1 expression level was correlated with tumor differentiation(P<0.001),lymph node metastasis(P=0.041),and TNM stage(P=0.042),while gender(P=0.617),age(P=0.054),T stage(P=1)and M stage(P=1)were not significantly correlated.3.DPEP1 and ASCL2 are highly expressed in colon cancer tissues.In colon cancer cells,DPEP1 can inhibit the degradation of ASCL2 protein through the ubiquitin pathway,and the transcription factor ASCL2 can increase the transcriptional activity of the DPEP1 promoter and the expression level of DPEP1,thereby forming a DPEP1/ASCL2 positive feedback loop to maintain the high expression levels of DPEP1 and ASCL2 in colon cancer cells.4.In colon cancer cells,DPEP1 can regulate stemness-related molecules and increase the resistance of colon cancer cells to irinotecan and oxaliplatin in an ASCL2-dependent manner.5.DPEP1 can promote colon cancer cell proliferation and subcutaneous tumor growth in nude mice.Conclusions:1.11 core genes involved in colon carcinogenesis were screened out,among which DPEP1 and ASCL2 had the highest correlation.2.The expression level of DPEP1 is correlated with clinicopathological characteristics(degree of tumor differentiation,lymph node metastasis,and TNM stage)of colon cancer patients.3.In colon cancer cells,DPEP1 maintains the high expression levels of DPEP1 and ASCL2 in cells by forming a DPEP1/ASCL2 positive feedback loop with ASCL2,thereby enhancing the resistance of colon cancer cells to chemotherapy drugs and promoting colon cancer cell proliferation.