| Objectives:1. To explore the associations between genetic variations of long non-coding RNA (lncRNA) and the risk of colorectal cancer.2. To investigate the effect of lncRNA genetic variations on the prognosis of colorectal cancer.3. To screen differentially expressed lncRNA associated with colorectal cancer.4. To validate part of differentially expressed lncRNA, and to explore the influence of the abnormal expression of those lncRNA on the prognosis of colorectal cancer.Methods:Case-control study was carried out to analyze the associations of lncRNA genetic variations with colorectal cancer susceptibility. Sequenome MassARRAY genotyping technology was used to determine the genotypes of candidate SNPs. Pearson Chi-square test, Cochran-Armitage trend test and unconditional Logistic regression were applied to examine the associations of the candidate SNPs with risk of colorectal cancer. Log-Rank test and Cox proportional hazards model were used to explore the effect of the SNP on overall survival of colorectal cancer patients. Using GEO database and analyzing the data set of lncRNA expression spectrum of colorectal cancer, we selected the differentially expressed lncRNA. GO and KEGG analyses were carried out to detcect the potential biological processes and signaling pathways the differentially expressed lncRNA might be involved in. Real-time quantitative PCR method was used to validate part of differentially expressed lncRNA. By the ROC curve, we assessed the ability of lncRNA to identify colorectal tumor tissues. Log-Rank test and Cox proportional hazards model were used to explore the effects of differentially expressed lncRNA on overall survival of colorectal cancer patients.Results:1. In the case-control study, we included 695 patients with colorectal cancer and 701 healthy controls. In the analysis of environmental risk factors, we found that smoking, drinking and family history of cancer were the risk factors of colorectal cancer, with the ORs of 1.42 (95% CI=1.14-1.81),1.93 (95%CI=1.43-2.59) and 1.73 (95%CI= 1.27-2.34), respectively. Smoking, drinking, obesity and family history of cancer showed no significant correlation with the overall survival of colorectal cancer patients (P>0.05).2. In the research on the relationship between genetic variations of lncRNA and colorectal cancer risk and prognosis,16 SNPs in lncRNA gene were analyzed. We did not find significant associations of the 16 SNPs with colorectal cancer susceptibility. But through stratified analyses, we found that among people younger than 58, PRNCR1 rs 13252298 GG genotype was borderline associated with the risk of colorectal cancer, with OR of 0.52 (95%CI=0.26-1.04). Among those older than 58, once UCA1 rs 12462414 added a T allele, the risk of colorectal cancer increaseed 33% (OR=1.33,95%CI=1.03-1.71). Among females, once UCA1 rs12462414 added a T allele, the risk of colorectal cancer increaseed 40%(OR=1.40,95%CI=1.04-1.87). Survival analysis found that, H19 rs2107425 CT genotype could increase the mortality risk of colorectal cancer compared with CC genotype, and the association was borderline with HR of 1.55 (P5%CI=0.99-2.41). H19 rs217727 each A allele increased, the the mortality risk of colorectal cancer increased 35%(HR=1.35, 95%CI=1.02-1.77). The colorectal cancer mortality risk for MALAT1 rs619586 GG genotype carriers was 10.31 times of that for AA carriers (95% CI=1.32-80.59).3. Through the analysis of GEO lncRNA expression profile about colorectal cancer, we found that 2474 lncRNA differentially expressed in colorectal tumor tissues, of which 1613 up-regulated. GO analysis found that differentially expressed lncRNA might be involved in thoese biological processes:interleukin-6 receptor binding, growth factor receptor binding, protein binding, regulation of cell growth, insulin-like growth factor binding, and so on. KEGG analysis found that differentially expressed lncRNA might be involved in these signaling pathways:fat digestion and absorp, intestinal immune network for IgA production, NOD-like receptors signaling pathways, inflammatory bowel disease, and so on.4. The validation analysis found that the expression level of lncRNA AK022914, AP000525.8 and UCA1 in the tissue of colorectal cancer were higher than that in normal tissues, and C17orf91 was lower expressed (P<0.05), which were consistent with the results of the chip. ROC analysis showed the AUC for AK022914, AP000525.8, UCA1 and C17orf91 were 70.5%,67.1%,68.5% and 67.1%, respectively. AK022914 had the best ability to identify colorectal tumor tissues and normal tissues, and its sensitivity and specificity could reach to 71.2% and 71.2%, respectively. UCA1 rs 12462414 genetic variation was found no significant correlation with the expression level of lncRNA UCA1. Survival analysis found that lower expression of lncRNA C17orf91 could significantly reduce the mortality risk of colorectal cancer (HR=0.21,95%CI=0.06-0.75).Conclusion:1. Smoking, drinking and family history of cancer were the risk factors of colorectal cancer.2. The lncRNA genetic variations were not associated with the risk of colorectal cancer. But among people older than 58 and women, UCA1 rs 12462414 genetic variation could increase the risk of colorectal cancer.3. The lncRNA H19 rs217727 and MALAT1 rs619586 genetic variations were associated with the overall survival of patients with colorectal cancer.4. The lncRNA AK022914, AP000525.8 and UCA1 were up-reglated in colorectal cancer tissues, and C17orf91 were down-regulated, which were possibly correlated with the occurrence of colorectal cancer.5. LncRNA C17orf91 lower expression could improve the overall survival of patients with colorectal cancer. The conclusions were still needed to be validated in large samples, and more biological researches were warranted to make clear the functions and mechanisms of lncRNA in occurrence and development of colorectal cancer. |
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