Hepatitis D virus genomic RNA in the etiology of liver cancer

描述（由申请人提供）：该提案基于早期的研究，描述了一种新的“开-关”可逆开关机制，该机制调节多种基因的转录，主要是控制细胞分裂和肿瘤发生的原癌基因。其机制包括PSF蛋白的抑制和内源性rna的抑制逆转，内源性rna结合并释放PSF基因。R21提案的总体目的是确定丁型肝炎病毒（HDV gRNA）的基因组RNA是否与内源性PSF结合RNA具有相同的致瘤功能，包括与PSF结合并逆转原癌基因的抑制。流行病学研究表明，HDV和HCV感染可引起HCC，需要与HBV合并感染才能帮助产生HDV颗粒，这与HBV引起HCC的流行观点相矛盾。分子证据表明HDV gRNA在体外优先与PSF蛋白结合，功能证据表明转染HDV gRNA转基因NIH3T3细胞可使NIH3T3细胞转化为致瘤细胞，这为流行病学证据提供了支持。受这些开创性发现的鼓舞，我们提出以下实验。(i) HDV gRNA基因转染NIH3T3细胞后，检测HDV gRNA与PSF蛋白的结合及诱导原癌基因Rab23的转录；（ii）将一种HDV gRNA转基因基因转染到小鼠肝脏中，检测其在肝脏中肿瘤的形成。我们期望这些实验将进一步支持HDV gRNA在HCC病因学中的致瘤作用，并为HDV感染诱导的HCC的诊断和治疗提供新的分子靶点。

DESCRIPTION (provided by applicant): The proposal is based on earlier studies describing a novel "on-off" reversible switch mechanism that regulates transcription of multiple genes, mainly proto-oncogenes that control cell division and tumorigenesis. The mechanism involves repression by PSF protein and reversal of repression by endogenous RNAs that bind and release PSF from a gene. The general aim of the R21 proposal is to determine whether the genomic RNA of hepatitis D virus (HDV gRNA) has the same tumorigenic function as endogenous PSF-binding RNAs, involving binding to PSF and reversing repression of proto-oncogenes. Epidemiological studies suggest that infection by HDV, and also by HCV, can cause HCC, and co-infection with HBV is required to provide help for producing HDV particles, contradicting the prevailing view that HBV causes HCC. The epidemiological evidence is bolstered by molecular evidence showing that HDV gRNA binds preferentially to PSF protein in vitro, and by functional evidence showing that transfection of NIH3T3 cells with a HDV gRNA transgene results in transformation of the NIH3T3 cells to tumorigenic cells. Encouraged by these seminal findings, we propose the following experiments. (i) Test for binding of HDV gRNA to PSF protein and induced transcription of the proto- oncogene Rab23 in NIH3T3 cells transfected with a HDV gRNA transgene; (ii) Test for formation of tumors in a mouse liver by transfecting a HDV gRNA transgene into the liver. We expect these experiments will provide further support for the proposed tumorigenic role of HDV gRNA in the etiology of HCC and lead to new molecular targets for diagnosing and treating HCC induced by HDV infection. PUBLIC HEALTH RELEVANCE: The proposal will test a novel mechanism that generates hepatocellular carcinoma (HCC) resulting from infection with hepatitis D virus (HDV), which contradicts the prevailing view that HBV causes HCC. We expect the results will identify new molecular targets for diagnosis and therapy of HCC.