Abstract 1467: A large set of miRNAs is deregulated since the earliest steps of human HCC

Abstract Introduction: Hepatocellular carcinoma (HCC) is the result of a stepwise process preceded by the development of premalignant lesions. To assess the involvement of microRNAs (miRNAs) in hepatocarcinogenesis it is critical to understand whether and which miRNAs are involved in the early stages of tumor development. To this end, changes in expression of miRNAs were investigated in low and high grade dysplastic nodules (LGDNs, HGDNs), early HCCs (eHCCs) and progressed HCCs (pHCCs). Materials and Methods: Small RNA sequencing (smallRNA-Seq) was applied to search for liver miRNAs and to profile their expression patterns in 14 cirrhotic nodules (CNs), 9 LGDNs, 6 HGDNs, 6 eHCCs and 20 pHCCs) from 17 patients with liver lesions of different etiology (HCV, HBV and alcohol). To investigate miRNAs differentially expressed in pHCCs towards their matched cirrhotic tissue, we applied the Random-Variance Model (F-test) and Multivariate Permutation Test (Fold Change, FC ≥ 2.0). QRT-PCR analysis was also performed on 14 additional patients with the same etiology of the first cohort for validation of the smallRNA-Seq results. Results: We identified a 62 miRNA expression signature that differentiates pHCCs from matched CNs. Notably, 52/62 miRNAs dysregulated in pHCCs were likewise altered in LGDN and HGDN, suggesting their possible role in HCC onset. Indeed, 28 miRNAs showed lower expression in CN that was significantly increased in LGDNs and remained high up to pHCCs. In contrast, 24 miRNAs displayed an opposite behavior, as their expression was very low or absent all throughout the tumorigenic process, compared to CNs. Interestingly, 2 miRNAs (let-7a-5p, miR-101-3p) showed a progressive decrease, suggesting that they are involved in later stages of the process. To further support the finding that dysregulation of miRNAs is a very early event in HCC development, we performed qRT-PCR in a series of LGDN, HGDN, eHCC and pHCCs from 14 additional patients. We selected for this analysis a handful of miRNAs found dysregulated by NGS analysis. The results demonstrate that all the 6 miRNAs examined (miR-429, miR-141-3p, miR-200a-3p and miR-200b-3p, miR-375 and miR-21-5p), were dysregulated at all stages of the tumorigenic process as compared to CNs. Conclusion: The results demonstrate that miRNAs deregulation may be a critical player in human hepatocarcinogenesis, from early stages to pHCC. They also suggest that some miRNAs might represent biomarkers useful for differential diagnosis of dysplastic and neoplastic liver lesions. Note: This abstract was not presented at the meeting. Citation Format: Francesca Rizzo, Luca Di Tommaso, Pia Sulas, Elena Coviello, Chiara Novello, Alessandro Weisz, Massimo Roncalli, Amedeo Columbano. A large set of miRNAs is deregulated since the earliest steps of human HCC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1467. doi:10.1158/1538-7445.AM2017-1467