To Study the Role of Vtrna2-1 in Repression of Tumor Recurrence and Vascular Invasion in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is still one of the leading cause death cancers worldwide. The liver resection is the major treatment for early stage HCC; nevertheless more than 50% of patients would suffer tumor recurrence and intrahepatic metastasis after resection; highlight the tumor recurrence is still an emergent issue for clinician or scientist.Vault RNA 2-1 (vtRNA2-1, also called nc886) is a novel transcript driven by POLIII promoter to generate a 108 nucleotide non-coding transcript that locate to chromosome 5q31. The expression of VTRNA2-1 is epigenetically controlled via its promoter that contained 13 CpG dinucleotides. The vtRNA2-1 was physically directly associated with the double-stranded RNA (dsRNA)-dependent kinase, protein kinase R (PKR) that also known as eukaryotic translation initiation factor 2-alpha kinase 2 (EIF2AK2). Knockdown expression of vtRNA2-1 lead to activation of PKR and its downstream NF-kB for cell survival; therefore, the vtRNA2-1 transcript was considered as tumor-suppressing. However; increasing evidences showed that VTRNA2-1 may function as oncogene and with other signaling cascade for tumor progression. In our study, we found that the differential hypermethylation of the VTRNA2-1 promoter (Tumor-Normal) was associated with a poor outcome in HCC patient survival after partial hepatectomies via log-rank test (P=0.004). Patients pertaining to the differential hypermethylation group tended to present with a larger tumor size (P=0.001), increased major hepatectomy (P=0.001), pathological vascular invasion (P=0.036) and increased stage III AJCC (P=0.03). These results suggested that silencing of VTRNA2-1 via methylation strongly associated increasing tumor growth and invasion in clinical specimen of HCCs; indicating expression of VTRNA2-1 might repress both pathological processing of cancers with unknown mechanisms. To address the issues, the objective of this grant will be to disclose the mechanism involved in VTRNA2-1 repress tumor recurrence and vascular invasion in hepatocellular carcinoma. We will achieve following specific aims within two years' project: (1). To evaluate VTRNA2-1 mediated signaling pathway in repression of tumors growth and invasion; (2). To study the interaction between VTRNA2-1 and candidate signaling molecules identified from specific aim-1; (3). Functional dissect VTRNA2-1 and the minimal VTRNA2-1 fragment in cancer cell growth, migration and cancer cell growth. During the first year, the VTRNA2-1 RNA fragment will be transfected into HCC cell lines, the transcriptome, and kinase phosphorylation will be revealed via gene expression microarray and phospho-kinase array; respectively. Integrated both gene expression versus kinase array data, the potential signaling pathway triggered via vtRNA2-1 will be analyzed via ingenuity pathway analysis (IPA). Functional analysis such as cell proliferation, cancer cell migration, endothelial cell migration and Chick Chorioallantoic Membrane (CAM) Assay will be analyzed via HCC cell lines with or without specific inhibitors targeting to vtRNA2-1 triggered signaling pathways. In the second year, the direct/or indirect physical interaction between VTRNA2-1 and signaling molecules will be revealed; the minimal function RNA domain of VTRNA2-1 will be also disclosed. By this way, we could understand role of VTRNA2-1 in its repression mechanism on tumor growth and vascular invasion of HCC. The minimal VTRNA2-1 fragment will be also test its inhibitory effect on cancer cells growth, migration.

Project ID:PC10908-0298
External Project ID:MOST109-2635-B182-002