Tumor-specific suicide gene therapy for hepatocellular carcinoma by transcriptionally targeted retroviral replicating vectors

Abstract

Replicating virus vectors are attractive tools for anticancer gene therapy, but the potential for adverse events due to uncontrolled spread of the vectors has been a major concern. To design a tumor-specific retroviral replicating vector (RRV), we replaced the U3 region of the RRV ACE-GFP with a regulatory sequence consisting of the hepatitis B virus enhancer II (EII) and human α-fetoprotein (AFP) core promoter to produce ACE-GFP-EIIAFP, a hepatocellular carcinoma (HCC)-targeting RRV. Similar to ACE-GFP, ACE-GFP-EIIAFP exhibited robust green fluorescent protein (GFP) expression in HCC cells and, most importantly, it exhibited HCC-specific replication and did not replicate in non-HCC tumor cells or normal liver cells. We sequenced the promoter region of ACE-GFP-EIIAFP collected from serial infection cycles to examine the genomic stability of the vector during its replicative spread, and found that the vector could retain the hybrid promoter in the genome for at least six infection cycles. In vitro studies revealed that ACE-CD-EIIAFP and ACE-PNP-EIIAFP, which express the yeast cytosine deaminase and Escherichia coli purine nucleoside phosphorylase, respectively, exert a highly potent cytotoxic effect on HCC cells in the presence of their respective prodrugs. In vivo, ACE-CD-EIIAFP-mediated suicide gene therapy efficiently suppressed HCC tumor growth and no detectable RRV signal was observed in extratumoral tissues. These results suggest that the tumor-specific, suicide-gene-encoding RRV may fulfill the promise of retroviral gene therapy for cancer.

Concepts for the Production of Viruses and Viral Vectors in Cell Cultures

“…Stable vectors are required because of the long residence times in vivo. These treatments typically involve doses of 100-1000 mL with a virus density of at least Gene therapy is currently used in ongoing clinical trials for the treatment of cancer [8], hereditary diseases [9], infectious diseases such as HIV infection [10,11] and tissue engineering [12]. The replication of the virus particle must be inactivated to ensure that the vector itself does not cause a disease.…”

Insights for hepatitis C virus related hepatocellular carcinoma genetic biomarkers: Early diagnosis and therapeutic intervention

“…Using of specific retroviral replicating vector (RRV) could inhibit the growth of HCC tumor and generate suicide gene therapy effectively with no detectable RRV signal in extratumoral tissues. The resulted tumor-specific suicide-gene-encoding RRV may achieve the engagement application of retroviral gene therapy for HCC cancer[111]. …”

Management strategies for hepatocellular carcinoma: old certainties and new realities

“…HCC onset and progression are related to molecular signatures from cirrhotic livers and single nucleotide polymorphism, and personalized clinical decision making to improve survival of HCC patients needs a translational approach, particularly in patients with refractory advanced/metastatic HCC referred for experimental therapies. HCC is a complex disease hallmarked by genomic diversity and classification of high-risk populations with a poor prognosis related to early tumor recurrence due to metastasis and late tumor recurrence due to de novo carcinogenesis after curative treatment would be valuable to design chemopreventive trials or to target cancer genes by biotherapies and tumor-specific suicide gene therapy [39][40][41][42][43]. Molecular profiling of HCC permits the progress of novel approaches to disease diagnosis, prognosis prediction, and treatment management as a paradigm of stratified medicine adapted to tumor biology through integration of clinical staging systems and molecular-based information to support clinical decision making.…”