Characterization of prognostic potential and functional roles of miR-1290 in hepatocellular carcinoma

Abstract

Abstract of thesis entitled Characterization of prognostic potential and functional roles of miR-1290 in hepatocellular carcinoma Submitted by LAM Yin Fan for the degree of Doctor of Philosophy at The University of Hong Kong in December 2019

Background and Objective: Hepatocellular Carcinoma (HCC) is one the most common malignancy worldwide. Liver resection and liver transplantation are the best surgical treatments for HCC patients. However, post-surgical HCC recurrence remains a significant clinical problem causing a very poor prognosis of HCC patients. Increasing evidences have proved that exosomal miRNAs represent specific and functional biomarkers. Here, we sought to identify HCC recurrence-associated exosomal miRNAs in HCC patients. We aimed to develop novel prognostic and therapeutic strategies to combat post-surgical HCC recurrence.

Materials and Methods: Pre-operative serum exosomes were isolated from HCC patients undergone hepatectomy. Low density array (LDA) analysis was performed to compare the miRNA profiles between patients with (N=6) and without (N=6) extrahepatic recurrence after hepatectomy. Differentially expressed miRNAs were validated using quantitative RT-PCR in a cohort of 71 HCC patients. The prognostic value of exosomal miRNAs in predicting HCC recurrence and survival of HCC patients after hepatectomy was evaluated. Lentivirus approach was used to stably knockdown the miR-1290 expression in HCC cells. Functional roles of miR-1290 in HCC cell growth and metastasis were investigated through in vitro and in vivo experiments. miR-1290 targeted genes were identified by RNA sequencing analysis and validated by in vitro assay and clinical samples.

Results: Isolated exosomes were characterized by NanoSight analysis, electron microscopy and western blot. Exosomal miR-1290 and miR-1246 were significantly overexpressed in HCC patients with post-surgical tumor recurrence compared to HCC patients without post-surgical tumor recurrence. Kaplan-Meier analysis showed either exosomal miR-1290 or miR-1246 was significantly associated with HCC recurrence and poor survival of HCC patients after liver resection. ROC analysis showed both exosomal miR-1290 (p=0.0009) and miR-1246 (p=0.006) could significantly predict HCC recurrence after liver resection. Importantly, combination of exosomal miR-1290, miR-1246 and alpha-fetoprotein could achieve a specificity of 83.8% in predicting tumor recurrence. Thus, the above data indicated that exosomal miRNAs could be potential prognostic biomarkers for HCC recurrence after hepatectomy. Knockdown of miR-1290 significantly repressed the proliferation and invasion of HCC cells by inhibiting the EMT process. Moreover, knockdown of miR-1290 significantly reduced the growth rate and metastatic ability of HCC cells in vivo. GLIPR1 was identified as the targeted gene of miR-1290 in HCC cells by RNA sequencing analysis. The expression level of GLIPR1 mRNA was inversely correlated with miR-1290 expression in HCC peritumoral tissue.

Conclusions: Serum exosomal miR-1290 and miR-1246 are promising prognostic biomarkers for predicting HCC recurrence after tumor resection. Targeted inhibition of miR-1290 may be a new therapeutic strategy to combat HCC progression and metastasis.