RERT-lncRNA调控EGLN2在肝细胞肝癌发生中的作用机制研究

As a new class of transcripts, long non-coding RNAs (lncRNAs) have been recently found to be pervasively transcribed in the genome. Multiple lines of evidence increasingly link dysregulations of lncRNAs to multiple human cancers. However, the biological functions of the vast majority remain unknown. Recent progress suggests that the involvement of lncRNAs in cancer could be far more prevalent than previously appreciated. Our previous studies have identified a novel polymorphism (rs10680577) within distal promoter of hypoxia-inducible factor prolyl hydroxylase 1 (PHD1, also known as EGLN2) which was significantly associated with both HCC incidence and prognosis in a Chinese population. Functional experiments revealed a strong genotype-phenotype correlation between rs10680577 and EGLN2. However, results from luciferase-based transient transfection system indicated that this correlation was not mediated by a differential promoter polymorphism-associated regulatory mechanism. On the other hand, we noticed that there existed a 2849-bp RAB4B-EGLN2 read-through long non-coding RNA (RERT-lncRNA) overlapping EGLN2 and the upstream RAB4B. Considering the fact that rs10680577 was located within RERT-lncRNA, we assume that rs10680577 may influence RERT-lncRNA expression by interrupting its folding structures, which in turn regulating EGLN2 expression, thus involved the development and prognosis of HCC. Based on our previous studies, in this proposal, we plan to further investigate the correlations and interactions among rs10680577, RERT-lncRNA and EGLN2, together with the impact of RERT-lncRNA overexpression on the proliferation, differentiation and metastasis of HCC tumor cells using genotype-phenotype correlation studies and functional analysis. Our proposal would help to fully elucidate the polymorphism-associated hepatocarcinogenesis mechanism conferred by lncRNAs and EGLN2 expressions and lay a foundation for further lncRNAs-related diagnosis and therapy of HCC.

长链非编码RNAs（lncRNAs）在基因组中广泛表达并以RNA的形式在多种层面调控基因表达。已有研究表明lncRNAs的异常表达与肿瘤的发生发展密切相关。我们近期的研究发现：位于prolyl羟化酶（EGLN2）远端启动子的一个遗传多态(rs10680577)与肝细胞肝癌（HCC）的发生、预后及EGLN2表达存在显著性相关，而这种相关不是该多态影响EGLN2启动子的转录而调控其表达。我们注意到EGLN2及其上游基因间存在一个通读长链非编码RNA（RERT-lncRNA），我们推测该多态可能通过影响长链非编码RNA的表达从而实现对其下游基因EGLN2的调控，进而参与HCC的发生和预后。本课题拟采用基因型-表型关联结合功能实验方法研究遗传多态、RERT-lncRNA和EGLN2三者间的依存关系及其对肿瘤细胞特征的影响，以期阐明遗传因素-lncRNA-EGLN2通路在HCC发生发展中的作用机制。

长链非编码RNAs（lncRNAs）在基因组中广泛表达并以RNA的形式在多种层面调控基因表达。研究表明lncRNAs的异常表达与肿瘤的发生发展密切相关。本课题经过大样本多中心病例对照结合后续功能实验研究发现中国人群中长链非编码RNA（RERT-lncRNA）中的一个四碱基（TTCA）插入缺失多态（rs10680577）与肝细胞肝癌（HCC）易感性存在显著关联，携带四碱基缺失基因型的个体患HCC的风险明显增加，而这种关联在经常吸烟患者中更为明显；rs10680577多态与RERT-lncRNA和prolyl羟化酶（EGLN2）的表达量均存在显著的基因型-表型关联，携带缺失基因型的组织和细胞较插入型，RERT-lncRNA和EGLN2的表达量均有明显的增加； RERT-lncRNA和EGLN2二者的表达量也存在显著线性相关，RERT-lncRNA的过表达能显著提高EGLN2的表达；同时结合生物信息学预测，rs10680577多态可能通过影响RERT-lncRNA的空间构象，影响RERT-lncRNA的表达，从而实现对其下游基因EGLN2表达的调控，进而参与HCC的发生。此外，课题组利用本项目剩余资金探讨了另外两个多态 rs35622507,rs199618935（分别位于KCNQ1OT1和PTPN11基因）与HCC易感性的关联性分析，结果显示这两个多态均与HCC发生存在显著关联，为HCC的早期诊断及预防提供了新的候选遗传标记。