结直肠癌miRNA相关基因单核苷酸多态性与预后相关性研究现状

目的:总结microRNA(miRNA)相关基因单核苷酸多态性(single nucleotide polymorphism,SNP)与结直肠癌患者预后的相关性研究,探讨miRNA相关基因SNPs在结直肠癌患者中的预后价值。方法:应用Medline及PubMed全文数据库检索系统,以"miRNA、单核苷酸多态性、癌症和预后"等为关键词,检索2008-07-2013-10的相关文献。纳入标准:1)miRNA相关基因SNP在癌症中的研究现状;2)miRNA相关基因SNP与结直肠癌患者预后的相关性研究。符合要求并纳入分析的文献39篇。结果:miRNAs是一类非编码小RNAs,可以与靶基因mRNA分子3′非翻译区域特异性结合来负调控蛋白表达。miRNA的突变、缺失或表达水平异常与肿瘤的发生发展密切相关。miRNAs表达水平的异常可作为结直肠癌预后相关的标志。编码miRNA的基因及相关的靶基因结合位点中也存在SNP,其可能通过miRNA转录、miRNA前体形成以及miRNA与mRNA的结合这3种不同的机制影响miRNA的调控,从而来影响结直肠癌患者的预后。miRNA相关基因SNPs(pre-miR-423的rs6505162、pre-miR-608的rs4919510、mir608的rs4919510、mir219-1的rs213210以及let-7f-2的rs17276588),在结直肠癌患者中的预后价值可能与肿瘤分期及治疗有关。结论:miRNA相关基因SNPs可作为预测结直肠癌患者预后的替代标志。     

XRCC1 R399Q基因多态性与结直肠癌易感性的Meta分析

目的探讨X—rayrepair cross—complementing group1（XRCC1）RB99Q基因多态性与结直肠癌易感性的关系。方法通过计算机检索和手工检索,收集有关XRCC1 R399Q基因多态性与结直肠癌易感性关系的文献,筛选出符合条件的文献,应用Meta分析软件对各项研究进行异质性检验,计算合并OR值及其95％可信区间,并行敏感性分析和发表偏倚的评估。结果国内外共有21篇文献纳入研究（结直肠癌组6229例;对照组10692例）。Meta分析结果显示：XRCC1 R399Q基因多态性在整个人群中与结直肠癌无明显的关联性（OR QQvs、RR=1．10,95％CI=0．90～1．35;OR QQ/RQvs.RR=1．02,95％CI=0．90～1．16;OR QQvs.RR/RQ=1．12,95％CI=0．95～1．33）。通过种族的分层分析发现XRCC1 R399Q基因多态性与结直肠癌易感性在亚洲人群和欧洲人群中无差异。结论XRCC1 R399Q基因多态性与结直肠癌间不存在明显的易感性。     

建立在芯片与生物信息学预测基础上的miRNA靶基因鉴定研究进展

microRNA(rniRNA)是一类长度约22个核苷酸(nt)的非编码单链小RNA分子.近年来,大鼍的研究证明,miRNA参与了许多重要的生物学过程,其异常表达在肿瘤的发生发展中扮演着癌基因或抑癌基因的角色.关于与肿瘤相关miRNA的实验研究方案通常包括4个步骤:①通过基因芯片技术对癌组织与配对的正常组织中差异表达的miRNA进行筛查,确定候选miRNA;②通过生物信息学软件对所获差异表达的miRNA进行靶基因预测,为后续鉴定差异表达miRNA的靶基因提供线索;③通过RISC免疫共沉淀、稳定同位素标记蛋白质谱或miRNA-mRNA复合物分析等实验方法对miRNA的靶基因进行实验室鉴定;④分析差异表达的miRNA及其靶基因与病理、肿瘤复发转移情况以及生存期等临床指标之间的相关关系,确定mjRNA的肿瘤生物学意义.在本文中,结合我们实验室最近利用基因芯片技术研究食管癌中差异表达miRNA及其靶基因的实验结果,综述了目前miRNA及其靶基因鉴定方面的最新研究进展.     

MicroRNA及其基因甲基化在结直肠癌的临床应用研究进展

微小RNA（microRNA,miRNA）是一类长18-25个核苷酸的非编码单链小分子RNA。近些年来,越来越多的研究提示miRNA表达异常参与肿瘤干细胞的自我更新、多能性维持、分化和分裂增殖等过程的调控。在消化系统肿瘤中尤其是在结直肠癌方面miRNA相关的研究较为深入。多项研究结果显示,miRNA及其基因甲基化在结直肠癌的早期检测及诊断、化疗疗效预测及预后预测方面都有着重要的意义。     

代谢酶基因多态性与结直肠癌易感性

外源致癌物进入机体后,需经一系列酶系统代谢活化或转化,成为终致癌物或毒性降低后排出体外.代谢酶的基因多态性使酶的活性有差异,可能为结直肠癌易感性的重要机制.现综述Ⅱ相代谢酶基因多态性与结直肠癌易感性的关系.     

中国人群XRCC1 Arg399Gln 基因多态性与结直肠癌易感性关系的Meta分析

摘 要：［目的］探讨X线修复交叉互补基因1（X-ray repair cross complementing group 1,XRCC1）Arg399Gln基因多态性与中国人群结直肠癌易感性的关系。［方法］在PubMed、MEDLINE、EMBASE、中国知网、维普、中国生物医学文献及万方数据库中检索建库至2016年4月10日之间发表的有关XRCC1 Arg399Gln基因多态性与中国人群结直肠癌易感性关系的相关文献。按照纳入和排除标准独立选择文献、提取资料,采用Stata 12.0软件进行Meta分析,计算合并比值比（OR）及其95%可信区间（95%CI）,并进行敏感性分析和发表偏倚的估计。［结果］ 共纳入11项研究,包括3502例患者和4828例对照者。Meta分析结果显示,在Gln/Gln vs Arg/Gln遗传模型中,XRCC1 Arg399Gln基因多态性与中国人群结直肠癌发生风险有显著相关性,与基因型Arg/Gln相比,基因型Gln/Gln增加了中国人群罹患结直肠癌的风险（OR=1.23,95%CI：1.04~1.46,P=0.016）。其余遗传模型中两者间无明显相关性。［结论］ 在Gln/Gln vs Arg/Gln遗传模型中,XRCC1 Arg399Gln基因多态性与中国人群结直肠癌易感性相关,基因型Gln/Gln增加中国人群罹患结直肠癌的风险。     

代谢酶基因多态性与结直肠癌易感性

外源致癌物进入机体后，需经一系列酶系统代谢活化或转化，成为终致癌物或毒性降低后排出体外。代谢酶的基因多态性使酶的活性有差异，可能为结直肠癌易感性的重要机制。现综述Ⅱ相代谢酶基因多态性与结直肠癌易感性的关系。     

胸苷酸合成酶基因多态性和饮酒习惯与结直肠癌易感性的关系

目的:研究胸苷酸合成酶(thymidylate synthase,TS)基因5′-非翻译区(untranslated region, UTR)、3′-UTR多态性及其与饮酒之间的联合作用和结直肠癌易感性的关系.方法: 采用以医院为基础的结直肠癌病例对照研究(结直肠癌新发病例300例,对照300例)方法,PCR-RFLP方法进行基因分型.结果:辽宁人群携带2R/2R基因型者发生结直肠癌风险程度下降,OR值为0 35(95%CI:0 12～0 98).TS 5′-UTR和3′-UTR与吸烟程度之间存在交互作用,P值分别为0 006和0 001;在吸烟≥16包年者中,TS 3′-UTR del6/del6基因型者患结直肠癌的风险明显下降,OR值为0 17(95%CI:0 05～0 56).TS 5′-UTR与饮酒年限之间存在交互作用,P=0 04.结论: TS 5′-UTR2R/2R基因是结直肠癌的保护因素,TS多态性与吸烟、饮酒之间存在一定的交互作用.     

结直肠癌相关成纤维细胞的microRNA的差异表达谱

目的:分析结直肠癌相关成纤维细胞(carcinoma associated fibroblasts,CAFs)与正常成纤维细胞(normal fibroblasts,NFs)的微小RNA(miRNA)表达谱差异。方法:收集结直肠癌组织和癌旁正常肠黏膜共3对,抽提、纯化RNA,加入荧光标记后与miRNA寡核苷酸基因芯片杂交,应用SAM软件进行数据分析,对有显著差异的miRNA进行实时荧光定量PCR验证,采用靶基因分析软件分析miRNA功能。结果:hsa-miR-138,hsa-miR-210,hsa-99a等12个miRNA在肿瘤组织中显著上调,中位假基因验出率(FDR)<5%;has-miR-29b、has-miR-494、has-miR-126等28个miRNA显著下调(FDR<5%)。结论:结直肠癌与正常结肠黏膜之间存在明显的miRNA差异表达谱,这些miRNA的差异性表达可能与结直肠癌的发病、侵袭、转移相关。     

利用网络分析预测As2O3治疗结直肠癌的靶基因

目的:探究三氧化二砷（arsenic trioxide,As2O3）作用于结直肠癌的靶基因。方法:利用pharmGKB数据库和drugbank5.0数据库分别提取三氧化二砷的直接靶基因,利用STRING10.5数据库筛选与三氧化二砷已知靶基因互相作用的蛋白,利用webGestalt数据库对互作蛋白进行通路分析和GO注释,运用cBioProtal数据库和The Human Protein Atlas 数据库对重点通路的核心基因进行变异和表达分析。结果:pharmGKB数据库和drugbank5.0数据库共提取出11个直接靶基因,STRING10.5数据库筛选出384个互作蛋白,webGestalt数据库的GO注释这384个靶基因主要集中于19类分子功能,在前10条通路中筛选出3条与结直肠癌有关的通路,3个核心基因在结直肠癌中存在点突变和基因缺失,其中NF-κB1和RELA在结直肠癌组织中存在高表达。结论:三氧化二砷可能通过 NF-κB信号通路治疗结直肠癌。     

Combinations of single nucleotide polymorphisms identified in genome-wide association studies determine risk for colorectal cancer

Genome-wide association studies (GWASs) have identified single nucleotide polymorphisms (SNPs) associated with colorectal cancer (CRC) risk, but whether these SNPs have additive effects on the risk of CRC remains unclear. We performed a systematic analysis of GWAS-identified SNPs using GWAS datasets from China (2,248 patients and 3,173 controls) and Europe (4,461 patients and 4,140 controls). We analyzed 58 independent variants from DNA samples from Chinese populations and found 19 SNPs that were significantly associated with CRC risk. We identified two genetic risk scores (GRSs) based on 58 and 19 SNPs, which were significantly associated with an increased risk of CRC. A decision curve analysis showed higher predictive power for the 58 SNPs. Using all the 58 SNPs to assess 5-year absolute risk (AR), we found that, at a cutoff of 0.4% (two times the median AR) and 0.6% (three times the median AR), approximately 32.76 and 16.45% of Chinese individuals were grouped as high risk for developing CRC, respectively. Risk stratification analysis further indicated that the population in the top 30% risk group accounted for 46.71% of the CRC cases. In addition, the 58 SNPs could explain approximately 1.13% of the phenotypic variance in Chinese populations. Similar findings were found in European populations. Combinations of SNPs identified in GWASs may therefore be useful for identifying individuals at high risk for CRC.     

Genetic variants in C‐type lectin genes are associated with colorectal cancer susceptibility and clinical outcome

Inflammatory responses play a vital role at different stages of colorectal carcinogenesis. C‐type lectins mediate inflammatory/immune responses and participate in immune escape of pathogens and tumors. Our study aimed to evaluate the correlation between polymorphisms in three C‐type lectin genes, CD209, MBL2 and REG4, and colorectal cancer (CRC) risk and clinical outcome. We genotyped 15 potentially functional single nucleotide polymorphisms (SNPs) and assessed their associations with CRC risk in a case‐control study of 1353 CRC cases and 767 healthy controls from the Czech Republic. We also analyzed these SNPs in relation to overall and event‐free survival in 414 patients. Two CD209 SNPs were associated with CRC risk after adjustment for multiple comparison. Minor allele carriers of the promoter SNP rs2287886 had an increased risk of CRC (OR 1.30, 95% CI 1.08–1.56), while minor allele carriers of the 3′UTR SNP, rs7248637, had a decreased risk (OR 0.74, 95% CI 0.60–0.91). Multivariate survival analyses, including age, gender, TNM stage and grade, showed that patients without distant metastasis at the time of diagnosis and carrying the rs2994809 T allele had a decreased overall and event‐free survival (HR 2.11, 95% CI 1.20–3.72 and HR 2.00, 95% CI 1.18–3.39, respectively). We show that SNPs in CD209 may affect CRC risk, while a SNP in REG4 may be a useful marker for CRC progression.     

Identification of candidate genes carrying polymorphisms associated with the risk of colorectal cancer by analyzing the colorectal mutome and microRNAome

BACKGROUND:

The presence of single‐nucleotide polymorphisms (SNPs) within the 3′‐untranslated regions of genes could affect the binding between a microRNA (miRNA) and its target, with consequences on gene expression regulation. Considering the important role of miRNAs in carcinogenesis, it is hypothesized here that these SNPs could also affect the individual risk of colorectal cancer (CRC).

METHODS:

To test this hypothesis, a list was developed of 140 somatically mutated genes deduced from previous works on the mutome of the CRC. A further selection was conducted of SNPs within target sites for miRNAs that are expressed only in the colorectum (the colorectal microRNAome) and having adequate population frequencies. This yielded 12 SNPs that were genotyped in a case‐control association study on 717 colorectal cases and 1171 controls from the Czech Republic.

RESULTS:

Statistically significant associations were found between the risk of CRC and the variant alleles of KIAA0182 (rs709805) (odds ratio = 1.57; 95% confidence interval = 1.06‐2.78, for the variant homozygotes) and NUP210 genes (rs354476) (odds ratio = 1.36; 95% confidence interval = 1.02‐1.82, for the variant homozygotes).

CONCLUSIONS:

The results support the study hypothesis and highlight the importance of SNPs within miRNA‐dependent regulatory regions. Further studies on the role exerted by NUP210 and KIAA0182 in colorectal carcinogenesis are warranted. Cancer 2012. © 2012 American Cancer Society.     

Association between microRNA genetic variants and susceptibility to colorectal cancer in Chinese population

MicroRNAs (miRNAs) play an important role in the pathogenesis of neoplasm. Single nucleotide polymorphisms (SNPs) within miRNAs can change their phenotype and function. We attempted to analyze the relationship between two SNP loci in miRNAs and colorectal cancer (CRC) in Chinese Han population. We genotyped the polymorphism of two common miRNA SNPs, miR-146a (rs2910164 G > C) and miR-499 (rs3746444 T > C), in a case–control study of 276 CRC cases and 373 healthy controls using polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP). The genotypes and allele frequencies of the two SNP loci were first compared between patients and controls and then further analyzed among subgroups of patients with different clinicopathological profiles. The rs2910164 CG genotype was significantly associated with a decreased risk of CRC [CG versus GG, odds ratio (OR)?=?0.567; 95 % confidence intervals (CIs)?=?0.338–0.952; p?=?0.031]. No significant differences of miR-499 genotype and allele distribution were detected between patients and controls. Comparison between groups divided by clinicopathologic features showed that the polymorphism of miR-146a was associated with the degree of tumor differentiation (p?=?0.014), and the G allele of rs2910164 trended to a mature differentiation (OR?=?0.553; 95 % CI?=?0.315–0.971; p?=?0.038). MiR-146a (rs2910164 G > C) polymorphism is associated with CRC susceptibility and histological differentiation in Chinese Han population.     

Evaluation of genetic variants in association with colorectal cancer risk and survival in Asians

Genome‐wide association studies (GWAS) have identified over 40 genetic loci associated with colorectal cancer (CRC) risk. The association of single nucleotide polymorphisms (SNPs) at these loci with CRC risk and survival has not been adequately evaluated in East Asians. GWAS‐identified CRC risk variants were used to construct weighted genetic risk scores (GRSs). We evaluated these GRSs in association with CRC risk in 3,303 CRC cases and 3,553 controls using logistic regression models. Associations with overall and CRC‐specific survival were assessed in 731 CRC patients using Cox regression models. The association between the GRSs (overall and Asian‐specific) and CRC risk was approximately twofold (highest vs . lowest quintile), and the shape of the dose–response was linear (p _trend = 1.24 × 10^?13 and 3.02 × 10^?14 for overall GRS and Asian‐specific GRS, respectively). The association of the GRS with CRC risk was stronger among those with a family history of CRC (p _interaction = 0.007). Asian‐specific GRS using previously reported survival SNPs increased risk for mortality and the shape of the dose–response was linear for CRC‐specific and all‐cause mortality (p _trend = 0.01 and 0.006, respectively). Furthermore, the minor alleles of rs6983267 and rs1957636 were associated with worse CRC‐specific and overall survival. We show that GRSs constructed using GWAS‐identified common variants are strongly associated with CRC risk in Asians. We confirm previous findings for the possible association between some SNPs with survival, and provide evidence for two additional CRC risk variants that may be related to CRC survival.     

Interleukin promoter polymorphisms and prognosis in colorectal cancer

There is strong evidence that cancer-associated inflammation promotes tumor growth and progression. This is especially true for colorectal cancer (CRC). Interleukins (ILs) are important modulators for inflammation. We examined whether promoter polymorphisms in key IL genes (IL4, IL4R, IL6, IL8 and IL10) are associated with the risk or clinical outcome of CRC. Five single-nucleotide polymorphisms (SNPs) were analyzed in genomic DNA from a cohort including 308 Swedish incident cases of CRC with data on Dukes' stage and up to 16 years of follow-up and 585 healthy controls. The selected SNPs have previously been shown to be functional and/or associated with cancer. None of the analyzed SNPs associated with the risk of CRC. When stratifying by tumor stage, significantly more patients carrying at least one G allele of IL10-1082 had tumors with Dukes' stages A + B than with stages C + D (P(trend) = 0.035 for genotype distribution). Analyzing associations with overall survival time, we found the rare T allele of IL4-590 to be related to a longer survival [CT versus CC Cox proportional hazard ratio 0.69, 95% confidence intervals 0.46-1.03, TT versus CC 0.32 (0.10-1.03)]. For IL6-174, the CG genotype was associated with a longer survival when compared with the CC genotype [0.64 (0.40-1.01)]. The present study was particularly suitable for survival analysis because all patients were sampled before the diagnosis of CRC. Our results suggest that the SNPs IL4-590 and IL6-174 may be useful markers for CRC prognosis. The predicted biological effect of these SNPs in relation to promotion of cancer progression is consistent with the observed increased survival time.     

Genetically determined elevated C-reactive protein associated with primary colorectal cancer risk: Mendelian randomization with lifestyle interactions

Systemic inflammation-related etiologic pathways via inflammatory cytokines in the development of colorectal cancer (CRC) have not been convincingly determined and may be confounded by lifestyle factors or reverse causality. We investigated the genetically predicted C-reactive protein (CRP) phenotype in the potential causal pathway of primary CRC risk in postmenopausal women in a Mendelian randomization (MR) framework. We employed individual-level data of the Women’s Health Initiative Database for Genotypes and Phenotypes Study, which consists of 5 genome-wide association (GWA) studies, including 10,142 women, 737 of whom developed primary CRC. We examined 61 GWA single-nucleotide polymorphisms (SNPs) associated with CRP by using weighted/penalized MR weighted-medians and MR gene-environment interactions that allow some relaxation of the strict variable requirements and attenuate the heterogeneous estimates of outlying SNPs. In lifestyle-stratification analyses, genetically determined CRP exhibited its effects on the decreased CRC risk in non-viscerally obese and high-fat diet subgroups. In contrast, genetically driven CRP was associated with an increased risk for CRC in women who smoked ≥ 15 cigarettes/day, with significant interaction of the gene-smoking relationship. Further, a substantially increased risk of CRC induced by CRP was observed in relatively short-term users (< 5 years) of estrogen (E)-only and also longer-term users (5 to > 10 years) of E plus progestin. Our findings may provide novel evidence on immune-related etiologic pathways connected to CRC risk and suggest the possible use of CRP as a CRC-predictive biomarker in women with particular behaviors and CRP marker-informed interventions to reduce CRC risk.     

SNPs in the Insulin-Like Growth Factor Gene and Obesity Impact on Colorectal Cancer in Egyptians

Background and aims: The insulin pathway may play a role in development of colorectal cancer (CRC). In this study, we investigated associations between CRC and obesity in Egyptians with reference to single nucleotide polymorphisms (SNPs) in the insulin-like growth factor-1 (IGF-I) gene. We also studied serum levels of IGF-1in Egyptian CRC patients with different BMI values. Methods: This prospective study included 66 CRC patients and 30 healthy individuals, for whom body mass index (BMI) was estimated, patients and controls being categorized into overweight or obese in one group and average weight in the other. Serum levels of IGF-1 were assessed by ELISA and SNPs in the IGF-I gene at rs6214C/T, rs6220 T/C and rs35767 C/T were examined by PCR- RFLP. Results: Serum levels of IGF-1 were significantly lower in both CRC average weight and overweight cases. IGF-1 could negatively predict CRC at a cut-off of 154 ng/ml with 87.5% sensitivity and 72.6 specificity. IGF-1 rs6214 CT and TT (T allele) genotypes were associated with a significantly increased risk of CRC. Univariate logistic regression showed that CRC risk significantly decreases by 0.14 for each one unit increase in IGF1. Conclusion: BMI could be considered as effect modifier for CRC risk. IGF-1 SNP rs6214 (TT and CT) are significantly associated with risk regardless of the BMI.     

microRNA-320a inhibits tumor invasion by targeting neuropilin 1 and is associated with liver metastasis in colorectal cancer

MicroRNAs (miRNAs) have been implicated in regulating diverse cellular pathways. Although there is emerging evidence that various miRNAs function as oncogenes or tumor suppressors in colorectal cancer (CRC), the role of miRNAs in mediating liver metastasis remains unexplored. The expression profile of miRNAs in liver metastasis and primary CRC tissues was analyzed by miRNA microarrays and verified by real-time polymerase chain reaction (PCR). In 62 CRC patients, the expression levels of miR-320a were determined by real-time PCR, and the effects on migration and invasion of miR-320a were determined using a transwell assay. miR-320a target genes were confirmed by luciferase assay, real-time PCR and western blot analysis. A set of miRNAs was found to be dysregulated in the liver metastasis tissues compared to matched primary CRC tissues, and the expression levels of miR-320a were significantly decreased in the liver metastasis tissues examined. miR-320a was correlated with tumor progression in CRC. miR-320a was downregulated in liver metastatic colon cancer cells and inhibited liver metastatic colon cancer cell migration and invasion. miR-320a directly binds to the 3'UTR of neuropilin 1 (NRP-1), a protein that functions as a co-receptor of vascular epithelial growth factor. miR-320a downregulated the expression of NRP-1 at both the mRNA and protein levels. These data demonstrated that miR-320a may be useful for identifying CRC patients that are at an elevated risk for developing liver metastasis. Our findings suggest that miR-320a may be a novel therapeutic candidate for the treatment of colorectal cancer.