Gene therapy of neoplastic liver diseases

Review of the Application of Dual Drug Delivery Nanotheranostic Agents in the Diagnosis and Treatment of Liver Cancer

Liver cancer has high incidence and mortality rates and its treatment generally requires the use of a combination treatment strategy. Therefore, the early detection and diagnosis of liver cancer is crucial to achieving the best treatment effect. In addition, it is imperative to explore multimodal combination therapy for liver cancer treatment and the synergistic effect of two liver cancer treatment drugs while preventing drug resistance and drug side effects to maximize the achievable therapeutic effect. Gold nanoparticles are used widely in applications related to optical imaging, CT imaging, MRI imaging, biomarkers, targeted drug therapy, etc., and serve as an advanced platform for integrated application in the nano-diagnosis and treatment of diseases. Dual-drug-delivery nano-diagnostic and therapeutic agents have drawn great interest in current times. Therefore, the present report aims to review the effectiveness of dual-drug-delivery nano-diagnostic and therapeutic agents in the field of anti-tumor therapy from the particular perspective of liver cancer diagnosis and treatment.

Intra-arterial interleukin-12 gene delivery combined with chemoembolization: anti-tumor effect in a rabbit hepatocellular carcinoma (HCC) model

BACKGROUND

Interleukin-12 (IL-12), a cytokine naturally secreted by activated dendritic cells and monocytes/macrophages, is known as a key anti-tumor agent in many tumor models, including hepatocellular carcinoma (HCC) models.

PURPOSE

To evaluate the anti-tumor effect of intra-arterial IL-12 gene delivery alone and in combination with transcatheter arterial chemoembolization (TACE) in rabbit VX2 liver cancer model.

MATERIAL AND METHODS

Rabbits with VX2 liver tumors were randomized into four groups, eight in each group. After laparotomy and insertion of a 30-gauge needle into the proper hepatic artery, the following interventional procedure protocols were applied: 0.9% saline solution (group A, control), TACE (group B, TACE alone, lipiodol + mitomycin), intra-arterial interleukin-12 gene infusion (group C, IL-12 alone), and intra-arterial interleukin-12 gene infusion in combination with TACE (group D, IL-12 plus TACE). Growth ratio was estimated by computed tomography. To analyze apoptotic index, tumor tissues were explanted for terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) staining, 14 days after therapy.

RESULTS

Significant differences of the relative tumor growth ratio were observed in TACE alone group and IL-12 plus TACE group in comparison with control (P < 0.05, ANOVA, Tukey's HSD correction) but not between IL-12 alone and control, or IL-12 plus TACE group and TACE alone group (P > 0.05). Significant changes of the apoptotic index were observed in group D in comparison with remaining three groups (P < 0.05). The difference between group C and group A was not significant statistically (P > 0.05).

CONCLUSION

Intra-arterial interleukin-12 gene therapy combined with TACE has a potent anti-tumor effect in rabbit VX2 liver cancer in comparison with TACE alone.

Inhibition of pancreatic carcinoma growth by adenovirus-mediated human interleukin-24 expression in animal model

Interleukin-24 (IL-24) has been shown to be a tumor-suppressor gene and the protein product found to be constitutively expressed by melanocytes, nerve cells, and some primary melanomas. The potential effect of adenovirus (AdV)-mediated IL-24 gene therapy was explored on human pancreatic carcinoma by using a pancreatic carcinoma cell line, patu8988. A recombinant adenovirus, AdVGFP/IL-24, expressing the marker, green fluorescent protein (GFP), and the tumor-suppressor gene, IL-24, was constructed. AdVGFP/IL-24 treatment of pancreatic carcinoma cells in vitro significantly induced pancreatic carcinoma cell cytotoxicity and apoptosis, compared with AdVGFP without IL-24 expression. In nude mice bearing patu8988 tumors, intratumoral injections of AdVGFP/IL-24 significantly inhibited pancreatic carcinoma growth. In addition, the molecular mechanism of tumor suppression was elucidated by downregulating the expression of vascular endothelial growth factor, CD34, and Bcl-2, as well as inhibiting tumor angiogenesis. Therefore, AdVGFP/IL-24 has the potential to serve as a novel tool for pancreatic carcinoma gene therapy.

Adenovirus-mediated Il-24 expression suppresses hepatocellular carcinoma growth via induction of cell apoptosis and cycling arrest and reduction of angiogenesis

Previous studies have shown that interleukin (IL)-24 as a novel tumor suppressor gene has tumor-suppressor activity in a broad spectrum of human cancer cells both in vitro and in vivo. In this study, we explored the potential effect of adenovirus-mediated IL-24 gene therapy on human hepatocellular carcinoma (HCC) by using a HCC cell line, SMMC-7721. We constructed a recombinant adenovirus, AdVGFP/IL-24 expressing the marker green fluorescent protein (GFP) and the tumor-suppressor gene, IL-24. We demonstrated that AdVGFP/IL-24 treatment of SMMC-7721 cells in vitro significantly induced HCC cell cytotoxicity and apoptosis, and altered HCC cell cycling with an S-phase reduction and G2/M phase arrest, compared with AdVGFP, without IL-24 expresssion (p < 0.05). Furthermore, we also showed that the treatment of SMMC-7721 tumors by an intratumoral injection of AdVGFP/IL-24 significantly suppressed in vivo HCC growth in athymic nude mice, compared with AdVGFP treatment (p < 0.05). In addition, we also elucidated the molecular mechanism responsible for AdVGFP/IL-24-associated tumor suppression. These include: (1) upregulation of p53-independent apoptosis-associated caspase-3 and (2) downregulation of angiogenesis-associated vascular endothelial growth factor and CD34. Therefore, this study will provide a framework for future clinical applications of AdVGFP/IL-24 in HCC gene therapy.

p53-expressing conditionally replicative adenovirus CNHK500-p53 against hepatocellular carcinoma in vitro

AIM: To develop a conditionally replicative gene-viral vector system called CNHK500-p53, which contains dual promoters within the E1 region, and combines the advantages of oncolytic virus and gene therapies for hepatocellular carcinoma (HCC).

METHODS: CNHK500-p53 was constructed by using human telomerase reverse transcriptase (hTERT) promoter to drive adenovirus E1a gene and hypoxia response element (HRE) promoter to drive adenovirus E1b gene. p53 gene expressing cassette was inserted into the genome of replicative virus. Viral replication experiments, cytopathic effect (CPE) and methyl thiazolyl tetrazolium (MTT) assay were performed to test the selective replication and oncolytic efficacy of CNHK500-p53.

RESULTS: Immunohistochemistry verified that infection with CNHK500-p53 was associated with selective replication of adenovirus and production of p53 protein in telomerase-positive and hypoxia-inducible factor-dependent HCC cells. p53 protein secreted from HepG2, infected with CNHK500-p53 was significantly higher than that infected with nonreplicative adenovirus Ad-p53 in vitro (388 ± 34.6 μg/L vs 76.3 ± 13.17 μg/L). Viral replication experiments showed that replication of CNHK500-p53 and CNHK500 or WtAd5, was much stronger than that of Ad-p53 in tested HCC cell lines. CPE and MTT assay indicated that CNHK500-p53 selectively replicated in and killed HCC cells while leaving normal cells unaffected.

CONCLUSION: A more efficient gene-viral system is developed by combining selective oncolysis with exogenous expression of p53 against HCC cells.

Histone deacetylase inhibitors for treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers in the world. Surgical resection has been considered the optimal treatment approach, but only a small proportion of patients are suitable candidates for surgery, and the relapse rate is high. Approaches to prevent recurrence, including chemoembolization before and adjuvant therapy after surgery, have proven to have a limited benefit; liver transplantation is successful in treating limited-stage HCC because only a minority of patients qualify for transplantation. Therefore, new therapeutic strategies are urgently needed. Because in addition to the classical genetic mechanisms of deletion or inactivating point mutations, epigenetic alterations, such as hyperacetylation of the chromatin-associated histones (responsible for gene silencing), are believed to be involved in the development and progression of HCC, novel compounds endowed with a histone deacetylase (HDAC) inhibitory activity are an attractive therapeutic approach. In particular, pre-clinical results obtained using HA-But, an HDAC inhibitor in which butyric acid residues are esterified to a hyaluronic acid backbone and characterized by a high affinity for the membrane receptor CD44, indicated that this class of compounds may represent a promising approach for hepatocellular carcinoma treatment.

Systemic efficacy of combined suicide/cytokine gene therapy in a murine model of hepatocellular carcinoma

BACKGROUND/AIMS

Gene therapy might be a promising therapeutic approach for advanced hepatocellular carcinoma (HCC) not amenable to any effective traditional treatment. The aim of the study was to evaluate the in vitro and in vivo efficacy of combined gene therapy of HCC with two different MoMLV-derived retroviral vectors, an MFG- and a LXSN-derived vector, both containing HSV-TK and hIL-2.

RESULTS

In vitro experiments on HCC cells showed efficient killing of transduced cells and efficient bystander effect after ganciclovir (GCV) treatment, with higher antitumor activity when the MFG-based vector was used. In vivo studies in a murine syngenic model of HCC demonstrated that treatment with GCV led to complete regression of tumors composed of transduced cells and regression of distant non-transduced tumors. Tumor transduction and efficacy of treatment was also demonstrated after in vivo delivery of vectors. Microarray analysis of tumor samples in mice receiving gene therapy showed up-regulation of genes involved in immune response and signal transduction.

CONCLUSIONS

We demonstrated the in vitro and in vivo efficacy of combined retroviral-mediated gene therapy for HCC, with significant systemic therapeutic efficacy in vivo.

Critical overview and outlook: pathogenesis, prevention, and treatment of hepatitis and hepatocarcinoma caused by hepatitis B virus

Viral hepatitis B is an enigmatic disease in which the host's own immune response to persistent viral infection may bring about host destruction through antiviral inflammatory responses which might otherwise present as a benign or inapparent disease. The simple solution to the hepatitis B problem is by immunoprophylaxis using the vaccine licensed in 1981, which prevents both infection and the late sequelae of liver cirrhosis and hepatocarcinoma. Immunotherapeutic vaccines against persistent hepatitis B infection have not been successful and new explorations are being directed to therapies which include antisense, ribozymes, gene silencing by RNA interference (RNAi) and aptamer approaches. Limited benefits from nucleoside therapy and limitations in opportunity for liver transplantation have left a large void of curative treatments. Findings with respect to e antigen tolerance provide a basis for exploration to determine whether passively administered e antigen might suppress cell-mediated immunity, creating a commensal state in which virus persists but without pathologic damage to the host. Therapy of hepatocarcinoma by conventional chemotherapy, radiation, or surgical resection and ablation gives little hope for restoration of health unless the tumor is detected very early. The large engagement of the world medical science community to develop therapeutic vaccines against cancer is now in major clinical trials to determine the hope and credibility for the immunization approach. Vaccines based on tumor peptides which are linked to heat shock proteins and directed to host dendritic cells give reason for excitement and may be the "best show in town". A new era of tumor therapy will need to be based on new discoveries in immune function which are required to pursue immunotherapy on a more rational basis. The many facets of current hepatitis B virology, pathogenesis, immunoprophylaxis, immunotherapeusis, chemotherapy, and tumor pathogenesis and therapy are discussed here, in depth, but in keeping with needed brevity.