ABSTRACT
BACKGROUND: Emerging studies have shown the potential benefit of arming oncolytic viruses with therapeutic genes. However, most of these therapeutic genes are placed under the regulation of ubiquitous viral promoters. Our goal is to generate a safer yet potent oncolytic herpes simplex virus type-1 (HSV-1) for cancer therapy. METHODS: Using bacterial artificial chromosome (BAC) recombineering, a cell cycle-regulatable luciferase transgene cassette was replaced with the infected cell protein 6 (ICP6) coding region (encoded for UL39 or large subunit of ribonucleotide reductase) of the HSV-1 genome. These recombinant viruses, YE-PC8, were further tested for its proliferation-dependent luciferase gene expression. RESULTS: The ability of YE-PC8 to confer proliferation-dependent transgene expression was demonstrated by injecting similar amount of viruses into the tumour-bearing region of the brain and the contralateral normal brain parenchyma of the same mouse. The results showed enhanced levels of luciferase activities in the tumour region but not in the normal brain parenchyma. Similar findings were observed in YE-PC8-infected short-term human brain patient-derived glioma cells compared with normal human astrocytes. intratumoural injection of YE-PC8 viruses resulted in 77% and 80% of tumour regression in human glioma and human hepatocellular carcinoma xenografts, respectively. CONCLUSION: YE-PC8 viruses confer tumour selectivity in proliferating cells and may be developed further as a feasible approach to treat human cancers.
Subject(s)
Brain Neoplasms/therapy , Glioma/therapy , Herpesvirus 1, Human/physiology , Oncolytic Virotherapy/methods , Animals , Brain Neoplasms/genetics , Brain Neoplasms/virology , Carcinoma, Hepatocellular/genetics , Carcinoma, Hepatocellular/therapy , Carcinoma, Hepatocellular/virology , Cell Cycle/genetics , Cell Line, Tumor , Chlorocebus aethiops , Female , Glioma/genetics , Glioma/virology , Herpesvirus 1, Human/genetics , Humans , Liver Neoplasms/genetics , Liver Neoplasms/therapy , Liver Neoplasms/virology , Luciferases/genetics , Mice , Mice, Nude , Mice, SCID , Regulatory Elements, Transcriptional , Transcription, Genetic , Transgenes , Vero Cells , Viral Proteins/genetics , Xenograft Model Antitumor AssaysABSTRACT
Hepatocellular carcinoma (HCC) is usually refractory to the available treatments. For cancer gene therapy purposes, real-time imaging of therapeutic gene expression is of great importance because there are multiple factors that modulate the therapeutic gene expression in a complex tumor microenvironment. As a consequence, multiple doses of therapeutic viral vectors may be required for improved efficacy. In the present study, the luciferase reporter gene and the yeast cytosine deaminase (yCD) genes were bicistronically expressed using the foot-and-mouth disease virus 2A peptide under the regulation of the cytomegalovirus (CMV) promoter. The effectiveness of the yCD/5-FC (5-fluorocytosine) killing efficacy mediated by the herpes simplex virus type 1 (HSV-1) amplicon viral vector was shown using HCC and non-HCC cell lines in vitro. In addition, in vivo experiment also showed tumor regression of a primary HCC 26-1004 tumor xenograft in tumor expressing high levels of the yCD gene (as determined by noninvasive imaging) after intratumoral injection of 1.5 × 10(6) TU HGCX-L2C HSV-1 amplicon viral vector and 5-FC administration. The HSV-1 amplicon viral vector coupled with the yCD/5-FC prodrug activated suicide gene could potentially be of use in clinical gene therapy for HCC.
Subject(s)
Carcinoma, Hepatocellular/therapy , Cytosine Deaminase/genetics , Flucytosine/therapeutic use , Genes, Transgenic, Suicide , Genetic Therapy/methods , Liver Neoplasms/therapy , Animals , Carcinoma, Hepatocellular/genetics , Cell Line, Tumor , Foot-and-Mouth Disease Virus/genetics , Genes, Reporter , Genetic Vectors , Green Fluorescent Proteins , Herpesvirus 1, Human/genetics , Humans , Liver Neoplasms/genetics , Luciferases/genetics , Luminescent Measurements/methods , Mice , Mice, Nude , Xenograft Model Antitumor AssaysABSTRACT
Targeting cell infection using herpes simplex virus type 1 (HSV-1) vectors is a complicated issue as the process involves multiple interactions of viral envelope glycoproteins and cellular host surface proteins. In this study, we have inserted a human glioma-specific peptide sequence (denoted as MG11) into a peptide display HSV-1 amplicon vector replacing the heparan sulfate-binding domain of glycoprotein C (gC). The modified MG11:gC envelope recombinant vectors were subsequently packaged into virions in the presence of helper virus deleted for gC. Our results showed that the tropism of these HSV-1 recombinant virions was increased for human glioma cells in culture as compared with wild-type virions. The binding of these recombinant virions could also be blocked effectively by pre-incubating the cells with the glioma-specific peptide, indicating that MG11 peptide and the recombinant virions competed for the same or similar receptor-binding sites on the cell surface of human glioma cells. Furthermore, preferential homing of these virions was shown in xenograft glioma mouse model following intravascular delivery. Taken together, these results validated the hypothesis that HSV-1 binding to cells can be redirected to human gliomas through the incorporation of MG11 peptide sequence to the virions.
