| Background and ObjectivesColorectal polyps refer to the protuberant lesions on the surface of intestinal mucosa,mostly in the rectum and sigmoid colon.And it has a certain tendency of malignancy.The development from benign colorectal polyps to malignant colorectal cancer is a multi-factor and multi-step process.If we can intervene in the stage of polyposis adenoma,we can effectively prevent the occurrence of colorectal cancer.At present,there are some drawbacks in the diagnosis of colorectal polyps.With the development of molecular biology,the research on molecular markers of colorectal cancer and colorectal polyps has become more and more in-depth.Peripheral blood susceptibility markers and miRNAs are relatively stable,less invasive and easy to detect.They have great application prospects as molecular markers of colorectal polyps.Therefore,the purpose of this study is to apply case-control study design to detect the molecular markers associated with colorectal polyps in peripheral blood,and combining traditional factors to establish risk assessment model and diagnostic model to explore the biological mechanism of the development from colorectal polyps to colorectal cancer,so as to assist in the diagnosis of colorectal cancer.Part 1 Evaluation of genetic susceptibility markers for colorectal polyp and construction of risk assessment modelMaterials and MethodsUsing case-control study design,1016 cases of colorectal polyp were included in the screening population for colorectal cancer in Jiashan County,Zhejiang Province,matching 999 normal individuals in the same period.The main characteristics,lifestyle and habits of the subjects were obtained by questionnaires,and 5 ml blood sample was extracted from each subject.Combined with GWAS Catalog database and meta-analysis and review of previous reports,64 susceptibility loci related to colorectal cancer were selected.The susceptibility loci were genotyped by MassArray technique.SPSS 20.0 software was used for statistical analysis.Simple count genetic risk score(SC-GRS),odds ratio weighted genetic risk score,(OR-GRS)and explained variance weighted genetic risk score(EV-GRS)were used to analyze the associations between positive susceptibility loci and colorectal polyp.ROC curve was used to evaluate the risk assessment model of colorectal polyp.ResultsSixty-four susceptibility loci were detected in 1016 colorectal polyp cases and 999 normal controls.Fifty-two susceptibility loci were included after excluding the unqualified loci.Among them,11 loci significantly associated with colorectal polyp risk were identified,including CCND2-AS1 rs10774214,IPOQ rs1501299,FASTKD3 rs1801394,COLCA1/COLCA2 rs3802842,SMAD7 rs12953717,SMAD7 rs4939827,ABCB1 rs1045642,miR-34b/c rs4938723,TGF-β1 rs1800469,VEGFA rs2010963,ERCC5 rs17655.Based on these 11 positive susceptibility loci,SC-GRS,OR-GRS and EV-GRS were calculated respectively.The cumulative risk effect showed an increasing trend with the increasing of GRS.Combining age,sex,BMI,smoking,drinking,tea drinking and family cancer history with GRS model,the AUC(95%CI)can reach 0.676(0.649-0.702),0.682(0.656-0.708)and 0.682(0.656-0.708),respectively.Part 2 Evaluation of plasma microRNA markers for colorectal polyp and construction of diagnostic modelMaterials and MethodsIn the discovery stage-internal validation stage-external validation stage,we recruited the colorectal polyp cases,normal controls in the screening population of Jiashan County,Zhejiang Province,and colorectal cancer cases in the Department of anorectal cancer,Shaoxing Hospital,Zhejiang University.In the discovery stage,we used Agilent Human miRNA chip through pooled sample design to screen candidate miRNAs.In the internal validation stage,the candidate miRNAs were quantitatively detected in independent samples,and the differentially expressed miRNAs were further screened.In the external validation stage,the quantitative detection of differentially expressed miRNAs in 300 cases of colorectal cancer,300 cases of colorectal polyp and 300 normal controls was carried out to explore the associations between the differentially expressed miRNAs and colorectal polyp.The diagnostic model of colorectal polyp was established,and the ROC curve was used to evaluate it.ResultsAfter discovery stage and internal validation stage,the external validation of hsa-mir-16-5p,hsa-mir-223-3p and hsa-mir-21-5p was performed in 300 cases of colorectal cancer,300 cases of colorectal polyp and 300 normal controls.Quantitative analysis showed that the expression levels of three miRNAs in colorectal polyp group were significantly higher than those in colorectal cancer group and normal control group(P<0.001).The diagnostic models of colorectal polyp based on hsa-mir-16-5p,hsa-mir-223-3p and hsa-mir-21-5p have good diagnostic efficacy.The AUC(95%CI)of these models can reach 0.818(0.786-0.851),0.746(0.710-0.782)and 0.680(0.644-0.716),respectively.The AUC(95%CI)of the combined diagnostic model was 0.838(0.806-0.870).After combining traditional risk factors such as age,gender,BMI,smoking,drinking,tea and family cancer history,the AUC(95%CI)of the combined model was 0.861(0.831-0.890).In the differential diagnosis model of colorectal polyp,the combined model with traditional risk factors has better diagnostic efficiency.ConclusionsThe first part of this study applied case-control study design to identify the susceptibility loci CCND2-AS1 rs10774214,IPOQ rs1501299,FASTKD3 rs1801394,COLCA1/COLCA2 rs3802842,SMAD7 rsl2953717,SMAD7 rs4939827,ABCB1 rs1045642,miR-34b/c rs4938723,TGF-β1 rs1800469,VEGFA rs2010963,ERCC5 rsl7655 were associated with the risk of colorectal polyp.SC-GRS,OR-GRS and EV-GRS were calculated by synthesizing 11 positive susceptibility loci.The risk assessment model of colorectal polyp based on traditional factors had better diagnostic efficacy.Its AUC(95%CI)could reach 0.676(0.649,0.702),0.682(0.656,0.708)and 0.682(0.656,0.708),respectively.The seond part of this study applied case-control study design to find out the expression levels of hsa-mir-16-5p,hsa-mir-223-3p and hsa-mir-21-5p in patients with colorectal polyp were significantly higher than those in patients with colorectal cancer and normal controls.The diagnostic models of colorectal polyp were constructed with hsa-mir-16-5p,hsa-mir-223-3p and hsa-mir-21-5p.The AUC(95%CI)could reach 0.818(0.786-0.851),0.746(0.710-0.782)and 0.680(0.644-0.716),respectively.The AUC(95%CI)of combined model was 0.827(0.796-0.858).After merging traditional risk factors,the model was further improved. |
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