A Novel RNA Oligonucleotide Improves Liver Function and Inhibits Liver Carcinogenesis In Vivo

Hepatocellular carcinoma (HCC) occurs predominantly in patients with liver cirrhosis. Here we show an innovative RNA-based targeted approach to enhance endogenous albumin production while reducing liver tumor burden. We designed short-activating RNAs (saRNA) to enhance expression of C/EBP (CCAAT/enhancer-binding protein-), a transcriptional regulator and activator of albumin gene expression. Increased levels of both C/EBP and albumin mRNA in addition to a 3-fold increase in albumin secretion and 50% decrease in cell proliferation was observed in C/EBP-saRNA transfected HepG2 cells. Intravenous injection of C/EBP-saRNA in a cirrhotic rat model with multifocal liver tumors increased circulating serum albumin by over 30%, showing evidence of improved liver function. Tumor burden decreased by 80% (P = 0.003) with a 40% reduction in a marker of preneoplastic transformation. Since C/EBP has known antiproliferative activities by way of retinoblastoma, p21, and cyclins, we used messenger RNA (mRNA) expression liver cancer-specific microarray in C/EBP-saRNA-transfected HepG2 cells to confirm down-regulation of genes strongly enriched for negative regulation of apoptosis, angiogenesis, and metastasis. Up-regulated genes were enriched for tumor suppressors and positive regulators of cell differentiation. A quantitative polymerase chain reaction (PCR) and western blot analysis of C/EBP-saRNA-transfected cells suggested that in addition to the known antiproliferative targets of C/EBP, we also observed suppression of interleukin (IL)6R, c-Myc, and reduced STAT3 phosphorylation. Conclusion: A novel injectable saRNA-oligonucleotide that enhances C/EBP expression successfully reduces tumor burden and simultaneously improves liver function in a clinically relevant liver cirrhosis/HCC model. (Hepatology 2014;58:216-227)