Data from Preclinical Evaluation of Transcriptional Targeting Strategy for Human Hepatocellular Carcinoma in an Orthotopic Xenograft Mouse Model

Abstract

<div>Abstract<p>Gene regulation of many key cell-cycle players in S-, G<sub>2</sub> phase, and mitosis results from transcriptional repression in their respective promoter regions during the G<sub>0</sub> and G<sub>1</sub> phases of cell cycle. Within these promoter regions are phylogenetically conserved sequences known as the cell-cycle–dependent element (CDE) and cell-cycle genes homology regions (CHR) sites. Thus, we hypothesize that transcriptional regulation of cell-cycle regulation via the CDE/CHR region together with liver-specific apolipoprotein E (apoE)-hAAT promoter could bring about a selective transgene expression in proliferating human hepatocellular carcinoma. We show that the newly generated vector AH-6CC-L2C could mediate hepatocyte-targeted luciferase gene expression in tumor cells and freshly isolated short-term hepatocellular carcinoma cultures from patient biopsy. In contrast, normal murine and human hepatocytes infected with AH-6CC-L2C expressed minimal or low luciferase activities. In the presence of prodrug 5-fluorocytosine (5-FC), AH-6CC-L2C effectively suppressed the growth of orthotopic hepatocellular carcinoma patient-derived xenograft mouse model via the expression of yeast cytosine deaminase (yCD) that converts 5-FC to anticancer metabolite 5-fluoruracil. More importantly, we show that combination treatment of AH-6CC-L2C with an EZH2 inhibitor, DZNep, that targets EpCAM-positive hepatocellular carcinoma, can bring about a greater therapeutic efficacy compared with a single treatment of virus or inhibitor. Our study showed that targeting proliferating human hepatocellular carcinoma cells through the transcriptional control of therapeutic gene could represent a feasible approach against hepatocellular carcinoma. <i>Mol Cancer Ther; 12(8); 1651–64. ©2013 AACR</i>.</p></div>