长链非编码RNA遗传变异与膀胱癌发病风险及其分子机制探讨

Long noncoding RNAs (lncRNAs) is widely defined as functional RNA longer than 200 nucleotides, without protein-coding capability. lncRNAs play a vital role in cancer occurrence and development. Genetic variants in lncRNAs also have been shown to be associated with susceptibility of cancer, while the detailed mechanism was still unclear. Previously, we have detected expression levels of cancer-related lncRNAs in bladder cancer (BC) tissues and found 5 lncRNAs were differently expressed in BC (i.e. H19, SNHG16, UCA1, MEG3 and PTENP1), suggesting that they may participate in carcinogenesis of BC. Based on the previous results, we plan to use case-control studies to assess the association between selected tagSNPs in the 5 lncRNAs and BC risk in our present study, as well as detect the potential interactions between gene-gene and gene-environment and analyze the relationship of genotype-clinical phenotype. Furthermore, we will also conduct some molecular biology assays to investigate effects of the associated SNPs on functions of lncRNAs and the underlying mechanism. Finally, we will detect expression levels of lncRNAs in plasma and evaluate practical value of lncRNAs as potential biomarkers of BC. This project will provide theoretical basis for the role of lncRNA in carcinogenesis of BC, and contribute to screening of susceptible population, individualized prevention, early diagnoses and treatment of BC.

长链非编码RNA（lncRNA）是长度超200个核苷酸的非编码功能性RNA，参与肿瘤发生发展，其遗传变异也与肿瘤发病风险密切关联，但确切机制尚不清楚。本课题组前期基于文献报道并经膀胱癌组织验证，筛选出5个差异表达lncRNAs（H19、SNHG16、UCA1、MEG3和PTENP1），提示其参与膀胱癌发生。本项目基于前期预研结果，拟运用病例-对照方法和标签SNPs策略，探讨5个候选lncRNAs基因遗传变异与膀胱癌发病风险的关系，并分析基因-基因、基因-环境交互作用及基因型-临床表型关系；进而采用分子生物学方法，探讨SNPs对lncRNAs功能学影响及其机制；最后，检测血浆lncRNAs表达水平，初步评估其作为膀胱癌生物标志物的价值。本研究为揭示lncRNAs在膀胱癌发生发展中的作用及其机制提供理论依据，并通过筛选潜在生物标志物，为膀胱癌易感人群筛查及个体化预防，早期诊断及治疗等提供参考。

LncRNA是一类长度超过 200 个核苷酸的非编码RNA。已有研究结果表明，lncRNAs可能是潜在的肿瘤生物标志物，lncRNAs上的单核苷酸多态性（SNPs）可通过多种途径影响lncRNAs正常功能的发挥，参与肿瘤的发生发展。本课题组基于文献报道并经膀胱癌组织进一步验证，筛选出差异表达 lncRNAs，探讨其参与膀胱癌发生发展的关联性及机制研究。LncRNA UCA1的rs12982687和吸烟存在明显的交互作用（OR = 1.29，95% CI = 1.06-1.58，P = 0.014），rs12982687C>T变异可以改变UCA1的二级结构、与miR-873-5p的结合能力、表达水平以及细胞恶性表型，影响尼古丁对膀胱癌细胞的促增殖及上调UCA1的作用。LncRNA H19的标签SNPs中，携带rs217727AA基因型个体罹患膀胱癌的发病风险比GG/GA基因型个体显著增加（OR = 1.31，95% CI = 1.03-1.67，P = 0.026）。LncRNA MEG3的所有SNPs，经本课题组膀胱癌全基因组关联性研究芯片分型、千人基因组计划数据进行填补之后，rs117763835，rs116907618，rs12431658，rs116328816以及rs35458454与膀胱癌发病风险显著相关。LncRNA SNHG16 rs4667885与膀胱癌的发病风险显著相关，通过eQTL发现当rs4647885存在C等位基因型时（TC+CC），SNHG16的表达显著低于只存在T等位基因型（TT）。SNHG16在细胞质中表达丰度显著高于细胞核中。最终显示其可发挥着ceRNA样作用来竞争性结合miR-140-5p，从而增加了GIT1的表达水平来影响膀胱癌的发生发展。血浆外泌体中lncRNA PTENP1在膀胱癌病人显著低表达（P = 0.031），ROC曲线下面积为0.613（95% CI：0.51-0.72），灵敏度为60%，特异度为64%，具有一定的诊断价值。PTENP1可以作为细胞间的通讯介质，并可通过miR-17调节PTEN表达。本研究揭示了lncRNAs上与膀胱癌易感性相关的SNPs，并通过一系列分子生物学技术探讨了关联SNPs的生物学功能，进一步评估了血浆lncRNAs作为膀胱癌易感标志物的价值，为膀胱癌的个体化预防和靶向治疗提供参考。