Gene therapy for hepatocellular carcinoma: progress but many stones yet unturned!

Radiofrequency hyperthermia-enhanced herpes simplex virus-thymidine kinase/ganciclovir direct intratumoral gene therapy of hepatocellular carcinoma

PURPOSE

To determine the feasibility of using radiofrequency hyperthermia (RFH) and to enhance the therapeutic effect of herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) for the treatment of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Human HCC cells (HepG2) were first transfected with lentivirus/luciferase. For both in vitro confirmation and in vivo validation, luciferase-labeled HCC cells and HCC tumour xenografts on mice received different treatments: (i) combination therapy of intratumoral HSV-TK/GCV-mediated gene therapy plus magnetic resonance imaging heating guidewire (MRIHG)-mediated RFH; (ii) gene therapy only; (iii) RFH only; and (iv) phosphate-buffered saline (PBS) as control. Cell proliferation was quantified. Tumour changes were monitored by ultrasound imaging and bioluminescence optical imaging before and at days 7 and 14 after treatments, which were correlated with subsequent histology.

RESULTS

In vitro, the lowest cell proliferation was seen in the combination therapy group compared with control groups (29 ± 6% vs. 56 ± 9%, 93 ± 4%, and 100 ± 5%, p < .05). Ultrasound imaging of treated animal xenografts showed smaller relative tumour volume in combination therapy group than those in three control groups (0.74 ± 0.19 vs. 1.79 ± 0.24, 3.14 ± 0.49 and 3.22 ± 0.52, p < .05). Optical imaging demonstrated significant decrease of bioluminescence signals of tumours in the combination therapy group, compared to those in three control groups (1.2 ± 0.1 vs. 1.9 ± 0.2% vs. 3.3 ± 0.6% vs. 3.5 ± 0.4%, p < .05). These imaging findings were correlated well with histologic confirmation.

CONCLUSION

RFH can enhance HSV-TK/GCV-mediated gene therapy of HepG2 cell line and mice human HCC xenografts, which may open new avenues for effective management of HCC using MR/RFH integrated interventional gene therapy.

The role of death receptor 3 in the biological behavior of hepatocellular carcinoma cells

Death receptor 3 (DR3) belongs to the tumor necrosis factor (TNF) receptor superfamily, primarily found in lymphoid tissues. Reports have determined that DR3 may also be distributed in numerous types of tumors. Therefore, it is thought that DR3 may have an important role in the process of tumorigenesis. The aim of the present study was to observe the effect of silencing DR3 expression on hepatocarcinoma cell growth, apoptosis and invasion in order to elucidate the role of DR3 in tumor development. The hepatocarcinoma cell lines (HepG2, Huh7, SMMC7721 and Bel-7402) and normal human liver cells (HL-7702) were transfected with three stealth RNA interference (RNAi) sequences that target the DR3 gene. Reverse transcription quantitative polymerase chain reaction was used to detect the expression levels of DR3 in hepatocarcinoma cell lines and normal liver HL-7702 cells. MTT assay and flow cytometry (FCM) were used to determine the rates of cell proliferation and apoptosis, respectively. Following silencing of the DR3 gene, western blot analysis was used to determine the protein expression of P53, Fas, Caspase8, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and Caspase3. DR3 messenger RNA (mRNA) expression in hepatocarcinoma cell lines was significantly increased compared with that in the normal liver cell line. Three targeted DR3 gene small interfering RNAs significantly inhibited DR3 gene expression in Bel-7402 cells at the nucleic acid level. AF02670.1_stealth_883 and cocktail demonstrated the most efficient inhibition of DR3 gene expression at 48 and 72 h following transfection, with mRNA inhibition rates of 89.46 and 92.75%, and 90.53 and 94.25% (P<0.01), respectively. Cell viability was significantly reduced by AF02670.1_stealth_883 and RNAi cocktail at 24, 48 and 72 h following transfection. The inhibition rates of cell proliferation were 50.76 and 61.76% (P<0.05) at 72 h following transfection. FCM revealed that AF02670.1_stealth_883 and RNAi cocktail also induced apoptosis in Bel-7402 cells at 72 h following transfection. Reduction of NF-κB and P53 levels was observed (P<0.05) in Bel-7402 cells following DR3 silencing, whereas levels of Fas, Caspase3 and Caspase8 were markedly elevated (P<0.05). DR3 expression levels in hepatocellular carcinoma cells were significantly higher than those in normal cells. DR3 silencing effectively inhibited proliferation and invasion of hepatocellular carcinoma cells in vitro. However, silencing of the DR3 gene affect levels of apoptosis antigen-3 ligand in cells, therefore indicating that it may be involved with other pathways that regulate apoptosis in HCCs. In conclusion, the results of the present study indicated that DR3 may be a promising therapeutic target molecule for further study of hepatocellular carcinoma gene therapy.

Adenoviral-mediated RNA interference targeting URG11 inhibits growth of human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the second most common malignancy in Asia, with a 5-year survival rate of less than 5% due to high recurrence after surgery and resistance to chemotherapy. A variety of therapeutic interventions to treat HCC, particularly gene therapy, have recently been investigated in tumor model systems to provide a more complete understanding of hepatocarcinogenesis and effectively design therapeutic strategies to treat this disease. In our study, we constructed an adenoviral vector expressing small interfering RNA (siRNA) targeting a newly discovered gene named upregulated gene 11 (URG11). We introduced this vector into HCC cells to investigate the role of URG11 in HCC carcinogenesis. We observed that upon URG11 knockdown, HCC cell proliferation was inhibited through downregulation of several G1-S phase related molecules including cyclin D1 and apoptosis was induced as a result of Bcl-2 downregulation. Besides decreased expression of cyclin D1, CDK4, pRb and Bcl-2, URG11 also suppressed several other proteins including CAPN9, which was identified by cDNA microarray and 2D gel electrophoresis. Moreover, Ad-URG11-siRNA significantly suppressed HCC tumor growth in nude mice. In conclusion, Ad-URG11-siRNA can significantly suppress HCC tumor growth in vitro and in vivo by silencing the URG11 gene, and the use of this vector for gene therapy may represent a novel strategy to treat human HCC.

Study on relationship between expression level and molecular conformations of gene drugs targeting to hepatoma cells in vitro

AIM: To increase exogenous gene expression level by modulating molecular conformations of targeting gene drugs.

METHODS: The full length cDNAs of both P₄₀ and P₃₅ subunits of human interleukin 12 were amplified through polymerase chain reaction (PCR) and cloned into eukaryotic expressing vectors pcDNA3.1 (±) to construct plasmids of P (+)/IL-12, P (+)/P₄₀ and P (-)/P₃₅. These plasmids were combined with ASOR-PLL to form two targeting gene drugs [ASOR-PLL-P (+)/IL-12 and ASOR-PLL-P (+)/P₄₀ + ASOR-PLL-P (-)/P₃₅] in optimal ratios. The conformations of these two drugs at various concentrations adjuvant were examined under electron microscope (EM) and the drugs were transfected into HepG2 (ASGr+) cells. Semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) was performed with total RNA extracted from the transfected cells to determine the hIL12 mRNA transcript level. The hIL12 protein in the cultured supernatant was measured with enzyme-linked immunosorbent assay (ELISA) 48 hours after transfection.

RESULTS: Targeting gene drugs, whose structures were granular and circle-like and diameters ranged from 25 nm to 150 nm, had the highest hIL-12 expression level. The hIL-12 expression level in the group co-transfected with ASOR-PLL-P (+)/P₄₀ and ASOR-PLL-P (-)/P₃₅ was higher than that of ASOR-PLL-P (+)/IL-12 transfected group.

CONCLUSION: The molecular conformations of targeting gene drugs play an important role in exogenous gene expression level, the best structures are granular and circle-like and their diameters range from 25 nm to 150 nm. The sizes and linking styles of exogenous genes also have some effects on their expression level.

A phase I study of autologous dendritic cell-based immunotherapy for patients with unresectable primary liver cancer

BACKGROUND/AIMS

To evaluate the safety and feasibility of immunotherapy based on autologous dendritic cells (DC) for patients with unresectable primary liver cancer (PLC).

METHODS

A total of ten patients were enrolled and immunized with DCs. Autologous DCs were generated ex vivo in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4). Cells were then pulsed with tumor lysate (TL), tumor necrosis factor-alpha (TNF-alpha) and keyhole limpet hemocyanin (KLH). Non-adherent cells were collected on day 9 and cells were administered into the inguinal lymph node. Each patient received 1-10 x 10(6) cells four times at weekly intervals.

RESULTS

Immunization was well tolerated in all patients without significant toxicity. DC vaccination induced delayed-type hypersensitivity (DTH) against KLH in seven out of ten patients. In one patient, one of the two liver tumors (tumor in segment 7, 13 mm in diameter) decreased in size to 7 mm and showed necrotic change on computed tomography examination after eight immunizations. In two patients, serum levels of tumor markers decreased after vaccination.

CONCLUSION

The present clinical trial suggested that immunization by TL-pulsed DCs is feasible in patients with unresectable PLC without any toxicity. Further improvement in the clinical results of immunotherapy might be expected by modifying the therapeutic protocol.

Photodynamic therapy for esophageal cancer: a useful and realistic option

The use of light therapy for tissue destruction is highly attractive for the endoscopic and minimally invasive therapy of esophageal cancer. Photodynamic therapy (PDT) offers the possibility of palliation of advanced obstructing tumors. However, there are other competing techniques, which can be used to open the esophageal lumen. It has also proved very effective in providing prolonged palliation of patients with advanced irresectable cancer. Completely obstructing tumors, tortuous and long lesions, and tumors near the upper end of the esophagus are particularly suitable for photodynamic therapy. Patients with obstruction to an esophageal prosthesis are also well palliated with PDT. A more interesting and exciting development is its use for the eradication of early asymptomatic mucosal disease. Photodynamic therapy is particularly useful for the eradication of field cancerous change in patients with pre-malignant Barrett's esophagus, or early tumors in patients unfit for radical therapy.

Hepatocellular carcinoma--cause, treatment and metastasis

In the recent decades, the incidence of hepatocellular carcinoma (HCC) has been found to be increasing in males in some countries. In China, HCC ranked second of cancer mortality since 1990s. Hepatitis B and C viruses (HBV and HCV) and dietary aflatoxin intake remain the major causative factors of HCC. Surgery plays a major role in the treatment of HCC, particularly for small HCC. Down-staging unresectable huge HCC to smaller HCC and followed by resection will probably be a new approach for further study. Liver transplantation is indicated for small HCC, however, some issues remain to be solved. Different modes of regional cancer therapy for HCC have been tried. Systemic chemotherapy has been disappointing in the past but the future can be promising. Biotherapy, such as cytokines, differentiation inducers, anti-angiogenic agents, gene therapy and tumor vaccine will probably play a role, particularly in the prevention of tumor recurrence. HCC invasiveness is currently the major target of study. Tremendous works have been done at the molecular level, which will provide clues for biomarker of HCC progression as well as targets for intervention.

Hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the sixth most common cancer of men and eleventh most common cancer of women world-wide. However, because almost every individual who develops liver cancer dies of the disease, HCC is the third most common cause of the cancer deaths in men and seventh most common in women. The treatment of choice for hepatocellular carcinoma remains surgical resection or liver transplantation, in carefully selected cases. In patients with hepatocellular carcinoma not amenable to surgical intervention a variety of different therapeutic interventions have been investigated. These include direct ablation of the tumour using agents such as ethanol or acetic acid, transcatheter arterial chemoembolization, or systemic chemotherapy. The evaluation of their efficacy is compromised by the paucity of adequately powered randomised clinical trials. The main challenge facing the research community over the next decade is to prioritise the most promising treatments and take these forward into multicentre controlled trials. Even if these fail to improve results, they will help reduce the variation in clinical practice by eliminating anecdotal treatment.

Antigen-specific immunotherapy for human papillomavirus 16 E7-expressing tumors grown in the liver

BACKGROUND/AIMS

We have previously reported a recombinant vaccinia-based vaccine (vac-Sig/E7/LAMP-1) that demonstrated a significant anti-tumor effect in a subcutaneous tumor challenge model. Since the liver is one of the most common sites for tumor metastasis and organ microenvironments may modulate tumor cell responses to therapies, the aim of the present study was to evaluate the potency of vac-Sig/E7/LAMP-1 in treating E7-expressing tumors grown in the liver.

METHODS

For in vivo tumor prevention experiments, mice were vaccinated intraperitoneally with vac-Sig/E7/LAMP-1 followed by intrahepatic tumor challenge. For in vivo tumor regression experiments, mice were first challenged with tumor cells and then vaccinated with vac-Sig/E7/LAMP-1 intraperitoneally. In addition, enzyme-linked immunospot assays were used to determine the frequency of E7-specific T cell precursors.

RESULTS

For in vivo tumor protection experiments, tumor growth was observed in all of the mice vaccinated with wild-type vaccinia and 60% of the mice vaccinated with wild-type E7 vaccinia. All of the mice vaccinated with vac-Sig/E7/LAMP-1 remained tumor-free 30 days after tumor challenge. For the tumor regression assays, all of the mice vaccinated with vac-Sig/E7/LAMP-1 remained tumor-free 30 days after vaccination. In contrast, all of those mice receiving culture medium, wild-type vaccinia, or wild-type E7 vaccinia developed tumors in the liver. In addition, mice vaccinated with vac-Sig/E7/LAMP-1 had the highest E7-specific CD8+ T cell precursors.

CONCLUSIONS

Our data suggest that vac-Sig/E7/LAMP-1 is an effective vaccine for controlling E7-expressing tumors grown in the liver and our model suggests that antigen-specific immunotherapy may represent a powerful tool for treating liver tumors with characterized tumor-specific antigens. In addition, our data indicate that the number of E7-specific CD8+ T cell precursors directly correlated with the anti-tumor effect generated by Sig/E7/LAMP-1 vaccinia.

Localized hepatocellular carcinoma: therapeutic options

Hepatocellular carcinoma (HCC) is among the most common malignancies worldwide. Recent surveillance programs have allowed early detection and diagnosis, but overall survival of patients with HCC remains poor. This article provides a definition for localized HCC and summarizes the array of treatments that have emerged and the salient literature and findings for each. Among the treatments reviewed here are surgical resection, orthotopic liver transplantation, and local ablative therapies such as cryosurgery, percutaneous ethanol injection therapy, and transarterial chemoembolization.

Locoregional treatments for hepatocellular carcinoma

Improvements in diagnostic techniques have enhanced our understanding of the natural history of hepatocellular carcinoma (HCC). This has facilitated a proper evaluation of the available treatment options for this neoplasm through both phase II studies and randomized controlled trials. Surgical resection and liver transplantation constitute the first two radical options, and when they are contra-indicated, patients may benefit from percutaneous ethanol injection or thermal ablation by radiofrequency current. These options may also achieve a complete response and constitute the last potentially radical therapies for small HCC. In contrast, for large multinodular tumours, the available treatment options have not been shown to improve survival. Arterial embolization with or without associated chemotherapy has been widely used. However, randomized controlled trials have failed to show a survival benefit, emphasizing the need to develop new treatment strategies.

Gene mutation of transforming growth factor beta1 type II receptor in hepatocellular carcinoma

Alteration of transforming growth factor beta1 (TGF-beta1) type II receptor (RII) appears to cause unresponsiveness to TGF-beta1 in tumorigenic cells. Defect in the mononucleotide repeat sequence, i.e., poly A region of TGF-beta1RII gene has been reported to be related to replication error-positive cancer cells. We examined if there is any TGF-beta1RII mutation in a coding microsatellite in hepatocellular carcinoma (HCC). Genomic DNAs were extracted from formalin-fixed, paraffin-embedded liver tissues obtained at surgery or autopsy in 3 normal individuals and 96 patients with hepatitis C virus-induced chronic liver disease; 3 with chronic hepatitis, 20 with liver cirrhosis and 73 with HCC. The DNA was PCR-amplified at 2 segments of TGF-beta1RII: poly A region which includes the (A)10 microsatellite sequence, and poly GT region. PCR products were directly sequenced. DNA from normal and patients with chronic liver disease contained the 10 wild-type adenines but 3 cases with liver cirrhosis in whom there were only 9 adenines within poly A tract. This microdeletion of one A resulted in a frameshift and truncated a predicted length of amino acids. In HCC lesions, the same deletion was noted in 4 cases (25%) of well-differentiated type, 10 (40%) of moderately differentiated type, 18 (53%) of poorly differentiated type. None of the lesions had mutations within the GT region. Our findings indicate that one adenine deletion of poly A microsatellite tract within TGF-beta1RII is frequently detected in patients with HCC, and the mutation may cause the abrogation of the function of TGF-beta1RII gene.

Enhanced antitumor effects of bone marrow transplantation in combination with fibroblast-mediated IL-2 and IL-3 gene therapy

BACKGROUND

Bone marrow transplantation (BMT) and gene therapy are potent approaches to the recovery of bone marrow depression and induction of antitumor immunity after chemotherapy for the treatment of malignancies. In the present study, enhanced antitumor effect of BMT in combination with fibroblast-mediated interleukin (IL)-2 and IL-3 gene therapy was observed in tumor-bearing mice after chemotherapy.

METHODS

BALB/c mice were inoculated s.c. with J558L plasmacytoma cells and injected i.p. with cyclophosphamide 300 mg/kg 3 days later. 24 hours after chemotherapy syngeneic bone marrow cells in combination with NIH3T3 fibroblast cells engineered to produce IL-2 (NIH3T3-IL-2) and/or NIH3T3 cells engineered to produce IL-3 (NIH3T3-IL-3) were implanted into the tumor-bearing mice.

RESULTS

BMT in combination with implantation of either NIH3T3-IL-2 or NIH3T3-IL-3 cells exerted significant inhibition on the growth of J558L tumors and prolonged the survival period of the tumor-bearing mice as compared with the treatments with Hanks solution, BMT alone, or BMT plus implantation of NIH3T3 cells transduced with Neo gene. Synergistic antitumor effect was observed in mice after combined BMT and cytokine gene therapy. The cytotoxicities of natural killer cells, cytotoxic T lymphocytes, and macrophages in mice increased markedly after the combined treatment. Recovery of CFU-GM, CFU-MK and CFU-E formation in mice after combined therapy was accelerated obviously in mice after combined therapy.

CONCLUSIONS

BMT in combination with fibroblast-mediated IL-2 and IL-3 gene therapy elicited augmented antitumor effects synergistically in tumor-bearing mice after chemotherapy mainly through induction of antitumor immune response and accelerated recovery of hematopoiesis.