The potential of gene therapy in the treatment of hepatocellular carcinoma

Gene therapy for people with hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma is the most common type of liver cancer, accounting for 70% to 85% of individuals with primary liver cancer. Gene therapy, which uses genes to treat or prevent diseases, holds potential for treatment, especially for tumours. Trials on the effects of gene therapy in people with hepatocellular carcinoma have been published or are ongoing.

OBJECTIVES

To evaluate the benefits and harms of gene therapy in people with hepatocellular carcinoma, irrespective of sex, administered dose, and type of formulation.

SEARCH METHODS

We identified randomised clinical trials through electronic searches in The Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, LILACS, Science Citation Index Expanded, and Conference Proceedings Citation Index-Science. We searched five online clinical trial registries to identify unpublished or ongoing trials. We checked reference lists of the retrieved studies for further trials. The date of last search was 20 January 2023.

SELECTION CRITERIA

We aimed to include randomised clinical trials assessing any type of gene therapy in people diagnosed with hepatocellular carcinoma, irrespective of year, language of publication, format, or outcomes reported.

DATA COLLECTION AND ANALYSIS

We followed Cochrane methodology and used Review Manager to prepare the review. The primary outcomes were all-cause mortality/overall survival (whatever data were provided), serious adverse events during treatment, and health-related quality of life. The secondary outcomes were proportion of people with disease progression, adverse events considered non-serious, and proportion of people without improvement in liver function tests. We assessed risk of bias of the included trials using RoB 2 and the certainty of evidence using GRADE. We presented the results of time-to-event outcomes as hazard ratios (HR), dichotomous outcomes as risk ratios (RR), and continuous outcomes as mean difference (MD) with their 95% confidence intervals (CI). Our primary analyses were based on intention-to-treat and outcome data at the longest follow-up.

MAIN RESULTS

We included six randomised clinical trials with 364 participants. The participants had unresectable (i.e. advanced inoperable) hepatocellular carcinoma. We found no trials assessing the effects of gene therapy in people with operable hepatocellular carcinoma. Four trials were conducted in China, one in several countries (from North America, Asia, and Europe), and one in Egypt. The number of participants in the six trials ranged from 10 to 129 (median 47), median age was 55.2 years, and the mean proportion of males was 72.7%. The follow-up duration ranged from six months to five years. As the trials compared different types of gene therapy and had different controls, we could not perform meta-analyses. Five of the six trials administered co-interventions equally to the experimental and control groups. All trials assessed one or more outcomes of interest in this review. The certainty of evidence was very low in five of the six comparisons and low in the double-dose gene therapy comparison. Below, we reported the results of the primary outcomes only. Pexastimogene devacirepvec (Pexa-Vec) plus best supportive care versus best supportive care alone There is uncertainty about whether there may be little to no difference between the effect of Pexa-Vec plus best supportive care compared with best supportive care alone on overall survival (HR 1.19, 95% CI 0.78 to 1.82; 1 trial (censored observation at 20-month follow-up), 129 participants; very low-certainty evidence) and on serious adverse events (RR 1.42, 95% CI 0.60 to 3.33; 1 trial at 20 months after treatment, 129 participants; very low-certainty evidence). The trial reported quality of life narratively as "assessment of quality of life and time to symptomatic progression was confounded by the high patient dropout rate." Adenovirus-thymidine kinase with ganciclovir (ADV-TK/GCV) plus liver transplantation versus liver transplantation alone There is uncertainty about whether ADV-TK/GCV plus liver transplantation may benefit all-cause mortality at the two-year follow-up (RR 0.39, 95% CI 0.20 to 0.76; 1 trial, 45 participants; very low-certainty evidence). The trial did not report serious adverse events other than mortality or quality of life. Double-dose ADV-TK/GCV plus liver transplantation versus liver transplantation alone There is uncertainty about whether double-dose ADV-TK/GCV plus liver transplantation versus liver transplantation may benefit all-cause mortality at five-year follow-up (RR 0.40, 95% CI 0.22 to 0.73; 1 trial, 86 participants; low-certainty evidence). The trial did not report serious adverse events other than mortality or quality of life. Recombinant human adenovirus-p53 with hydroxycamptothecin (rAd-p53/HCT) versus hydroxycamptothecin alone There is uncertainty about whether there may be little to no difference between the effect of rAd-p53/HCT versus hydroxycamptothecin alone on the overall survival at 12-month follow-up (RR 3.06, 95% CI 0.16 to 60.47; 1 trial, 48 participants; very low-certainty evidence). The trial did not report serious adverse events or quality of life. rAd-p53/5-Fu (5-fluorouracil) plus transarterial chemoembolisation versus transarterial chemoembolisation alone The trial included 46 participants. We had insufficient data to assess overall survival. The trial did not report serious adverse events or quality of life. E1B-deleted (dl1520) adenovirus versus percutaneous ethanol injection The trial included 10 participants. It did not report data on overall survival, serious adverse events, or health-related quality of life. One trial did not provide any information on sponsorship; one trial received a national research grant, one trial by the Pedersen foundation, and three were industry-funded trials. We found five ongoing randomised clinical trials.

AUTHORS' CONCLUSIONS

The evidence is very uncertain about the effects of gene therapy on the studied outcomes because of high risk of bias and imprecision of outcome results. The trials were underpowered and lacked trial data on clinically important outcomes. There was only one trial per comparison, and we could not perform meta-analyses. Therefore, we do not know if gene therapy may reduce, increase, or have little to no effect on all-cause mortality or overall survival, or serious adverse events in adults with unresectable hepatocellular carcinoma. The impact of gene therapy on adverse events needs to be investigated further. Evidence on the effect of gene therapy on health-related quality of life is lacking.

Redox-responsive polymer inhibits macrophages uptake for effective intracellular gene delivery and enhanced cancer therapy

The development of advanced gene delivery carriers with stimuli-responsive release manner for tumor therapeutics is desirable, since they can exclusively release the therapeutic gene via their structural changes in response to the specific stimuli of the target site. Moreover, interactions between macrophages and drug delivery systems (DDSs) seriously impair the treatment efficiency of DDSs, thus macrophages uptake inhibition would to some extent improve the intracellular uptake of DDSs in tumor cells. Herein, a PEGylated redox-responsive gene delivery system was developed for effective cancer therapy. PEG modified glycolipid-like polymer (P-CSSO) was electrostatic interacted with p53 to form P-CSSO/p53 complexes, which exhibited an enhanced redox sensitivity in that the disulfide bond was degraded and the rate the plasmid released from P-CSSO was 2.29-fold that of nonresponsive platform (P-CSO-SA) in 10 mM levels of glutathione (GSH). PEGylation could significantly weaken macrophages uptake, while enhance the accumulation of P-CSSO in tumor cells both in vitro and in vivo. Compared with nonresponsive complexes (P-CSO-SA/p53) (59.2%) and Lipofectamine™ 2000/p53 complexes (52.0%), the tumor inhibition rate of P-CSSO/p53 complexes (77.1%) significantly increased, which was higher than CSSO/p53 complexes (69.9%). The present study indicates that tumor microenvironment sensitive and macrophages uptake suppressive P-CSSO/p53 is a powerful in vivo gene delivery system for enhanced anticancer therapy.

Reconstructed adeno-associated virus with the extracellular domain of murine PD-1 induces antitumor immunity

BACKGROUND

The negative signaling provided by interactions of the co-inhibitory molecule, programmed death-1 (PD-1), and its ligands, B7-H1 (PD-L1) and B7-DC (PD-L2), is a critical mechanism contributing to tumor evasion; blockade of this pathway has been proven to enhance cytotoxic activity and mediate antitumor therapy. Here we evaluated the anti-tumor efficacy of AAV-mediated delivery of the extracellular domain of murine PD-1 (sPD-1) to a tumor site.

MATERIAL AND METHODS

An rAAV vector was constructed in which the expression of sPD-1, a known negative regulator of TCR signals, is driven by human cytomegalovirus immediate early promoter (CMV-P), using a triple plasmid transfection system. Tumor-bearing mice were then treated with the AAV/sPD1 construct and expression of sPD-1 in tumor tissues was determined by semi quantitative RT-PCR, and tumor weights and cytotoxic activity of splenocytes were measured.

RESULTS

Analysis of tumor homogenates revealed sPD-1 mRNA to be significantly overexpressed in rAAV/sPD-1 treated mice as compared with control levels. Its use for local gene therapy at the inoculation site of H22 hepatoma cells could inhibit tumor growth, also enhancing lysis of tumor cells by lymphocytes stimulated specifically with an antigen. In addition, PD-1 was also found expressed on the surfaces of activated CD8+ T cells.

CONCLUSION

This study confirmed that expression of the soluble extracellular domain of PD-1 molecule could reduce tumor microenvironment inhibitory effects on T cells and enhance cytotoxicity. This suggests that it might be a potential target for development of therapies to augment T-cell responses in patients with malignancies.

14-kDa Phosphohistidine phosphatase plays an important role in hepatocellular carcinoma cell proliferation

14-kDa Phosphohistidine phosphatase (PHP14), the first histidine phosphatase protein identified in vertebrates, was recently revealed to play an essential role in lung cancer. The function of this gene in other tumors is unclear; however, in this study, we demonstrate that PHP14 is highly expressed in hepatocellular carcinoma (HCC) tissues and cell lines compared with adjacent non-cancerous human liver tissues and cells (P<0.05). We used lentivirus-mediated delivery of small interfering RNA (siRNA) to knockdown the expression of PHP14 in an HCC cell line and investigate the effects of PHP14 on cell growth in vitro. Cell proliferation was inhibited and cell apoptosis was significantly increased. PHP14-siRNA affected the cell cycle and promoted G1→S phase transition in HCC cells. These results demonstrate that the knockdown of PHP14 expression by lentivirus-delivered siRNA may be a useful therapeutic approach for the treatment of HCC.

Expression and modulation of Na(+) /H(+) exchanger 1 gene in hepatocellular carcinoma: A potential therapeutic target

BACKGROUND AND AIM

Na(+) /H(+) exchanger 1 (NHE1), a regulator of intracellular pH (pHi), plays a significant role in regulating tumor cell growth and apoptosis. In the present study, we determined its role in hepatocellular carcinoma (HCC).

METHODS

Immunohistochemistry was carried out to detect NHE1 expression in HCC tissue for the correlation of NHE1 with clinicopathological data from patients. NHE1-siRNA and 5- (N-ethyl-N-isopropyl) amiloride (EIPA, highly specific inhibitor of NHE1) were used to assess the function of NHE1 in HCC cells by using gene transfection, methyl thiazolyl tetrazolium (MTT), flow cytometry, and nude mouse xenograft assays as well as fluorescence spectroscopy.

RESULTS

We found that NHE1 expression was increased in HCC tissues and cells in which its expression was associated with the increased tumor size, venous invasion and advanced tumor stages. However, suppression of NHE1 expression by using NHE1-siRNA and EIPA reduced growth, but induced apoptosis of HCC cells. EIPA also inhibited tumor growth in nude mouse xenografts of HCC cells.

CONCLUSIONS

The data from our current study demonstrates that NHE1 was overexpressed in HCC and that inhibition of NHE1 could be a potential therapeutic target for HCC.

NT4(Si)-p53(N15)-antennapedia induces cell death in a human hepatocellular carcinoma cell line

AIM: To construct the recombinant lentivirus expression plasmid, pLenti6/V5-NT4 p53(N15)-antennapedia (Ant), and study its effect on HepG2 cells.

METHODS: Plasmid pLenti6/V5-NT4 p53(N15)-Ant was constructed incorporating the following functional regions, including signal peptide sequence and pro-region of neurotrophin 4, N-terminal residues 12-26 of p53 and 17 amino acid drosophila carrier protein, Ant. Hepatocellular carcinoma (HepG2) cells were used for transfection. 3-[4,5-dimethyl-thiazol-2yl]-2,5 diphenyl tetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) release assay, transmission electron microscopy (TEM) and flow cytometric analysis (FCM) were employed to investigate the effects of LV-NT4(Si)-p53(N15)-Ant in vitro on HepG2 cells. In vivo experiment was also performed to investigate the inhibitory effect of LV-NT4(Si)-p53(N15)-Ant on tumor growth in nude mice.

RESULTS: LV-NT4(Si)-p53(N15)-Ant significantly suppressed the growth of HepG2 cells. MTT assay showed that the growth of HepG2 cells was mucj more significantly inhibited by LV-NT4(Si)-p53(N15)-Ant than by LV-EGFP. The inhibition rate for HepG2 cell growth in the two groups was 46.9% and 94.5%, respectively, 48 h after infection with LV-NT4(Si)-p53(N15)-Ant, and was 33.9% and 95.8%, respectively, 72 h after infection with LV-NT4(Si)-p53(N15)-Ant (P < 0.01). Light microscopy and TEM showed morphological changes in HepG2 cells infected with LV-NT4(Si)-p53(N15)-Ant, but no significant changes in HepG2 cells infected with LV-EGFP. Changes were observed in ultra-structure of HepG2 cells infected with LV-NT4(Si)-p53(N15)-Ant, with degraded membranes, resulting in necrosis. LDH release from HepG2 cells was analyzed at 24, 48, 72 and 96 h after infection with LV-NT4(Si)-p53(N15)-Ant and LV-EGFP, which showed that LDH release was significantly higher in LV-NT4(Si)-p53(N15)-Ant treatment group (682 IU/L) than in control group (45 IU/L, P < 0.01). The longer the time was after infection, the bigger the difference was in LDH release. FCM analysis showed that LV-NT4(Si)-p53(N15)-Ant could induce two different kinds of cell death: necrosis and apoptosis, with apoptosis being the minor type and necrosis being the main type, suggesting that LV-NT4(Si)-p53(N15)-Ant exerts its anticancer effect on HepG2 cells by inducing necrosis. The in vivo study showed that LV-NT4(Si)-p53(N15)-Ant significantly inhibited tumor growth with an inhibition rate of 66.14% in terms of tumor size and weight.

CONCLUSION: LV-NT4(Si)-p53(N15)-Ant is a novel recombinant lentivirus expression plasmid and can be used in gene therapy for cancer.

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.

Molecular therapy and prevention of liver diseases

Molecular analyses have become an integral part of biomedical research as well as clinical medicine. The definition of the molecular and genetic basis of many human diseases has led to a better understanding of their pathogenesis and has in addition offered new perspectives for their diagnosis, therapy and prevention. Genetically, liver diseases can be classified as hereditary monogenic, acquired monogenic, complex genetic and diseases. Based on this classification, gene therapy is based on six concepts: gene repair, gene substitution, cell therapy, block of gene expression or function, DNA vaccination as well as gene augmentation. While recent developments are promising, various delivery, targeting and safety issues need to be addressed before gene therapy will enter clinical practice. In the future, molecular diagnosis and therapy liver diseases will be part of our patient management and complement existing diagnostic, therapeutic and preventive strategies.

Adenovirus-delivered CIAPIN1 small interfering RNA inhibits HCC growth in vitro and in vivo

Hepatocellular carcinoma (HCC) is an aggressive cancer with a poor prognosis. The specific cellular gene alterations responsible for hepatocarcinogenesis are not well known. Cytokine-induced antiapoptotic molecule (CIAPIN1), a recently reported antiapoptotic molecule which plays an essential role in mouse definitive hematopoiesis, is considered a downstream effecter of the receptor tyrosine kinase–Ras signaling pathway. However, the exact function of this gene in tumors is not clear. In this study, we reported that CIAPIN1 is highly expressed in HCC as compared with non-tumor hepatic tissue (P < 0.05). We employed adenovirus-mediated RNA interference technique to knock down CIAPIN1 expression in HCC cells and observed its effects on HCC cell growth in vitro and in vivo. Among the four HCC and one normal human liver cell lines we analyzed, CIAPIN1 was highly expressed in HCC cells. Knock down of CIAPIN1 could inhibit HCC cell proliferation by inhibiting the cell cycle S-phase entry. Soft agar colony formation assay indicated that the colony-forming ability of SMMC-7721 cells decreased by ∼70% after adenovirus AdH1-small interfering RNA (siRNA)/CIAPIN1 infection. In vivo experiments showed that adenovirus AdH1-siRNA/CIAPIN1 inhibited the tumorigenicity of SMMC-7721 cells and significantly suppressed tumor growth when injected directly into tumors. These results suggest that knock down of CIAPIN1 by adenovirus-delivered siRNA may be a potential therapeutic strategy for treatment of HCC in which CIAPIN1 is overexpressed.

Application of doxorubicin-induced rAAV2-p53 gene delivery in combined chemotherapy and gene therapy for hepatocellular carcinoma

p53 gene transfer has been proposed as a potential therapeutic option for treatment of hepatocellular carcinoma (HCC). Compared to other commonly used gene transfer vectors such as adenovirus and retrovirus, recombinant adeno-associated virus serotype 2 (rAAV2) has shown promising results in human clinical trials. Significant enhancement in the gene transfer efficiency is needed, however, for HCC applications. In the present study, we applied chemotherapy drug Doxorubicin (DOX) to induce rAAV2 transduction of hepatomas. Using reporter assays, we showed that the DOX-treated hepatomas became more susceptible to rAAV2 infection in comparison to untreated controls: the permissiveness increased >350-fold and >120-fold for HepG2 (p53 wild-type) and Hep3B (p53 null) hepatomas, respectively. Using the induced permissiveness, we applied rAAV2-p53 transduction to restore p53 expression in the p53-null Hep3B hepatomas. Compared to rAAV2-p53 transduction alone, rAAV2-p53 transduction with DOX resulted in a >16-fold induction of p53 expression. The transduced Hep3B expressed as much as 380% more immunoreactive p53 in comparison to the wild-type p53 expression in the HepG2 hepatomas. Significantly, when Hep3B cells were treated with 0.5 muM of DOX and rAAV2-p53 (MOI = 10) for twelve hours, the cell viability dropped to 66% four days after the administration. This decrease in cell viability was similar to that of treatment with 1 microM of DOX alone in the absence of rAAV2. The 50% reduction in DOX administration--from 1 microM to 0.5 microM--revealed the antitumor property of the rAAV2-p53 transduction as well as the joint cytotoxicity of DOX and rAAV2-p53 against the p53-null hepatomas. We conclude that DOX mediates the enhancement effect on rAAV2 transduction of human hepatomas. Combined DOX and rAAV2-p53 administration may facilitate more efficient treatment for the HCC caused by p53 mutations.

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.

Inhibitory effect of recombinant adenovirus carrying immunocaspase-3 on hepatocellular carcinoma

Previously, Srinivasula devised a contiguous molecule (C-cp-3 or immunocaspase-3) containing the small and large subunits similar to that in the active form of caspas-3 and found C-cp-3 had similar cleavage activity to the active form of caspase-3. To search for a new clinical application of C-cp-3 to treat hepatocellular carcinoma, recombinant adenoviruses carrying the C-cp-3 and a-fetoprotein (AFP) promoter (Ad-rAFP-C-cp-3) were constructed through a bacterial homologous recombinant system. The efficiency of adenovirus-mediated gene transfer and the inhibitory effect of Ad-rAFP-C-cp-3 on the proliferation of hepatocarcinoma cells were determined by X-gal stain and MTT assay, respectively. The tumorigenicity of hepatocarcinoma cells transfected by Ad-rAFP-C-cp-3 and the antitumor effect of Ad-rAFP-C-cp-3 on transplanted tumor in nude mice were detected in vivo. The results suggested that Ad-rAFP-C-cp-3 can inhibit specifically proliferation of AFP-producing human hepatocarcinoma cells in vitro and in vivo and adenovirus-mediated C-cp-3 transfer could be used as a new method to treat human hepatocarcinoma.

Oncolytic adenovirus-mediated E1A gene therapy induces tumor-cell apoptosis and reduces tumor angiogenesis leading to inhibition of hepatocellular carcinoma growth in animal model

Oncolytic adenovirus (rAd)-mediated E1A gene therapy of cancer has become a novel therapeutic modality. In this study, we constructed a recombinant oncolytic adenovirus (rAd-E1A) expressing the tumor suppressor E1A gene. We demonstrated that the rAd-E1A replicated in HepG2 and SMMC-7721 human hepatocellular carcinoma (HCC) cells but attenuated in the normal liver cell line HL-7702. It induced HCC cell apoptosis through upregulation of apoptosis-associated Bax, caspase-3, and Fas and downregulation of survivin and Bcl-2 in a p53-dependent pathway. It also downregulated the expression of angiogenesis- associated vascular endothelial growth factor (VEGF) and CD34 genes and reduced tumor vessel formation and angiogenesis. In mice bearing SMMC-7721 tumors, intratumoral injections of rAd- E1A significantly inhibited HCC growth. Therefore, the oncolytic adenovirus-mediated E1A gene therapy may be a useful therapeutic approach for HCC treatment.

Gene therapy of liver tumors with human liver-specific nanoparticles

The development of safe and efficient liver-specific gene delivery approaches offers new perspectives for the treatment of liver disease, in particular, liver cancer. We evaluated the therapeutic potential of hepatotropic nanoparticles for gene therapy of liver tumor. These nanoparticles do not contain a viral genome and display the hepatitis B virus L antigen, which is essential to confer hepatic specificity. It has not been shown whether a therapeutic effect could be obtained using L nanoparticles in a human liver tumor xenograft model. Rats bearing human hepatic (NuE) and non-hepatic tumors were injected with L nanoparticles containing a green fluorescent protein (GFP) expression plasmid. GFP expression was observed only in NuE-derived tumors but not in the non-hepatic tumor. The potential for treatment of liver tumors was analyzed using L nanoparticles containing the herpes simplex virus thymidine kinase gene, in conjunction with ganciclovir pro-drug administration. The growth of NuE-derived tumors in L particle-injected rats was significantly suppressed, but not of the non-hepatic tumor control. In summary, this is the first demonstration that nanoparticles could be used for delivery of therapeutic genes with anti-tumor activity into human liver tumors. This intravenous delivery system may be one of the major advantages as compared to many other viral vector systems.

Inhibitory effect of recombinant adenovirus carrying melittin gene on hepatocellular carcinoma

OBJECTIVES

To search for a new clinical application of melittin (Mel): treating hepatocellular carcinoma with Mel gene.

METHODS

Recombinant adenoviruses carrying the Mel gene and alpha-fetoprotein (AFP) promoter (Ad-rAFP-Mel) were constructed through a bacterial homologous recombinant system. The efficiency of adenovirus-mediated gene transfer and the inhibitory effect of Ad-rAFP-Mel on the proliferation of hepatocarcinoma cells were determined by X-gal stain and MTT assay, respectively. The tumorigenicity of hepatocarcinoma cells transfected by Ad-rAFP-Mel and the antitumor effect of Ad-rAFP-Mel on transplanted tumor in nude mice were detected in vivo.

RESULTS

The Mel mRNA was transcribed in BEL-7402 hepatocellular carcinoma cells transducted by Ad-rAFP-Mel. The efficiency of adenovirus-mediated gene transferred to BEL-7402 cells was 100% when the multiplicity of infection of Ad-rAFP-Mel was 10 in vitro, and was also high in vivo. The inhibitive rates of Ad-rAFP-Mel and Ad-rAFP for BEL7402 cells were 66.2 +/- 2.7% and 2.9 +/- 2.3% (t=30.83, P=6.6 x 10(-6)) by MTT assay. The inhibitive rates of Ad-CMV-Mel for BEL7402, SMMC7721 and L02 cells were 58.9 +/- 9.6%, 65.9 +/- 3.8% and 31.7 +/- 1.2%, respectively, and of Ad-rAFP-Mel were 66.2 +/- 2.7%, 16.1 +/- 6.6% and 7.5 +/- 3.3%, respectively (t=1.27, P=0.27; t=11.31, P=3.5 x 10(-4); and t=12.12, P=2.7 x 10(-4) versus the Ad-CMV-Mel group in the same cells). The tumorigenicity rates of hepatocarcinoma cells transfected by Ad-rAFP-Mel were decreased. A significant antineoplastic effect was detected on transplanted tumor in nude mice by intratumoral injection of Ad-rAFP-Mel.

CONCLUSIONS

Ad-rAFP-Mel can inhibit specifically proliferation of AFP-producing human hepatocarcinoma cells in vitro and in vivo. This suggests that animal toxin gene can be used as an antitumor gene.

Rapid cloning and expression of hepatocellular carcinoma associated cDNA fragments

AIM: To clone and characterize novel genes that might be involved in hepatocellular carcinoma.

METHODS: An EST fragment differentially expressed between hepatocellular carcinoma (HCC) and its adjacent nontumorous liver tissues had been cloned using suppression subtractive hybridization (SSH). With this approach, we identified a novel EST that consisted of 447bp. In order to gain its full-length cDNA fragment, two gene-specific primers were designed for 3'-rapid amplification of cDNA end RACE. One HCC cell line, HepG2, was maintained in the RPMI1640 media and recommended culture conditions. Total RNA was extracted from HepG2 by the SV Total RNA Isolation System (Promega). RACE reactions were prepared using the SMART^TM RACE cDNA amplification kit (Clontech). Initial amplification was carried out with gene-specific primer 3'GSP2(5'-CGCATAGT ACCAGTATCGACAAAGG-3'), followed by nested PCR using gene-specific primer 3'NGSP2(5'-TCCACATTACGGACCCGACGGATT-3'). These amplified cDNA fragments obtained from RACE were subcloned into the PMD18-T vector (TaKaRa) and sequenced by ABI PRISM377 DNA sequencer. Basic local aligment search tools were carried out using BLASTN and dbEST and nr database. Northern blot was applied to detect the expression of these cDNA fragments between HCC and its adjacent nontumorous liver tissues. A total of 3 liver specimens were collected from the Southwest Hospital of Chongqing in China. The final diagnosis of HCC was confirmed by histological examination. Total RNA was extracted from either HCC or its adjacent nontumorous liver tissues in the same way. These cDNA fragments were excised from the PMD18-T vector, purified and ³²P-labeled as cDNA probes using the random primed labeling method. Northern blot was prepared by using the ExpressHyb^TM hybridization solution (Clontech) according to the protocol provided by the manufacturer. Combination of Northern blot and virtual Northern (http://www.ncbi.nlm.nih.gov/SAGE)(series analysis of gene expression, SAGE), expression of these cDNA fragments in multiple carcinoma and normal tissues were analyzed.

RESULTS: Five EST fragments (694 447-3, 724 447-3, 697 447-3, 711 447-3, 692 447-3) were cloned, including two EST fragments with ploy (A) tail (694 447-3, 724 447-3). Compared with ESTs in GeneBank, the two EST fragments with ploy (A) tail represented novel genes with a common sequence. Five EST fragments accession numbers in Genebank were CK730344, CK730345, CK730346, CK730347, CK730348, respectively. Northern blot revealed that 694 447-3, 724 447-3 presented higher expression in HCC than that in its adjacent nontumorous liver tissues. Virtual Northern blot (SAGE) revealed that 694 447-3, 724 447-3 presented higher expression in multiple cancers that contained in brain, colon, breast, lung and stomach than that in their normal tissues.

CONCLUSION: Two novel human hepatocellular carcinoma-associated cDNA fragments are identified. RACE technique is a rapid and effective method for seeking for disease related genes in specific tissues.

An oncolytic adenoviral vector of Smac increases antitumor activity of TRAIL against HCC in human cells and in mice

Hepatocellular carcinoma (HCC) displays a high resistance to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated cell death. To increase sensitivity of HCC cells to TRAIL, we have constructed an oncolytic adenoviral vector (ZD55) and used this vector to deliver second mitochondria-derived activator of caspases (Smac) and TRAIL genes (ZD55-Smac and ZD55-TRAIL, respectively) into HCC cells. Our data showed that human HCC cells express high levels of inhibitor of apoptosis proteins (IAPs). Transfected HCC cells expressing exogenous X-linked IAPs (XIAPs) displayed more resistance to TRAIL. The expression of Smac led to rapid and potent activation of apoptosis in HCC cells after infection with ZD55-Smac. The activation of caspases and induction of apoptosis could be enhanced further through coinfection with ZD55-TRAIL. The combined treatment of ZD55-Smac and ZD55-TRAIL resulted in significant reduction of XIAP expression levels. In addition, our in vivo data in mice showed only a partial response in the established tumor treated either by ZD55-Smac or ZD55-TRAIL alone. By contrast, complete tumor regression was observed by combination of ZD55-Smac and ZD55-TRAIL in all treated animals. This strong antitumoral activity achieved by this combination was due to a dramatic induction of tumor cell apoptosis in the treated tumors. In conclusion, our data indicate that Smac antagonizes the IAPs in HCC tumor cells and enhances tumor cell death induced by TRAIL in the oncolytic adenoviral vector. The combination of Smac and TRAIL delivered by way of the oncolytic adenoviral vector would provide a useful strategy for therapy of HCC and might also be applied to other IAPs abundant in cancers.

Prolonged and inducible transgene expression in the liver using gutless adenovirus: a potential therapy for liver cancer

BACKGROUND AND AIMS

Gene therapy of liver diseases would benefit from systems allowing prolonged, regulable, and tissue-specific transgene expression. We attempted to produce a vector fulfilling these requirements.

METHODS

We generated gutless adenoviral vectors containing a mifepristone (RU486)-inducible system for controlled and liver-specific expression of human interleukin-12 (hIL-12) (GL-Ad/RUhIL-12) and mouse IL-12 (mIL-12) (GL-Ad/RUmIL-12). The properties of these vectors were tested both in vitro and in vivo.

RESULTS

Infection of cells with GL-Ad/RUhIL-12 resulted in high level of hIL-12 expression in the presence of RU486 only in hepatocytic cells. In animals injected with GL-Ad/RUhIL-12, the administration of RU486 induced a transient rise of serum hIL-12 that peaked at 10 hours and completely disappeared by 72 hours. The peak value of hIL-12 was dependent on the doses of the vector and the inducer. High and sustained serum levels of hIL-12 could be attained by continuing administration of RU486 every 12 or 24 hours. Repetitive induction of hIL-12 could be obtained over, at least, a period of 48 weeks after a single injection of GL-Ad/RUhIL-12. Although the vector was detected in many tissues after systemic injection, transcription of the transgene was only found in the liver. Treatment of liver metastases with 5 x 10(8) infectious units of GL-Ad/RUmIL-12 plus RU846 resulted in complete tumor regression in all animals.

CONCLUSION

Gutless adenoviral vectors allow liver-specific and regulable transgene expression for prolonged periods of time. These vectors are promising tools for gene therapy of liver cancer and could also be useful for other forms of hepatic disease.

Gene therapy of hepatocarcinoma: a long way from the concept to the therapeutical impact

Hepatocellular carcinoma (HCC), the most prevalent histological form of primary liver cancer is one of the most frequent cancer worldwide. This pathology still requires the development of new therapeutical approaches. Gene therapy strategies focusing on the genetic manipulation of accessory cells involved in the immune reaction against cancer cells, or on the direct transduction of tumor cells with transgenes able to "suicide" cancer cells have been largely developed for more than ten years.

Hepatoma cell-specific ganciclovir-mediated toxicity of a lentivirally transduced HSV-TkEGFP fusion protein gene placed under the control of rat alpha-fetoprotein gene regulatory sequences

Suicide gene therapy combining herpes simplex virus thymidine kinase gene transfer and ganciclovir administration can be envisioned as a powerful therapeutical approach in the treatment of hepatocellular carcinoma; however, safety issues regarding transgene expression in parenchyma cells have to be addressed. In this study, we constructed LATKW, a lentiviral vector expressing the HSV-TkEGFP gene placed under the control of the promoter elements that control the expression of the rat alpha-fetoprotein, and assayed its specific expression in vitro in hepatocarcinoma and nonhepatocarcinoma human cell lines, and in epidermal growth factor stimulated human primary hepatocytes. Using LATKW, a strong expression of the transgene was found in transduced hepatocarcinoma cells compared to a very low expression in nonhepatocarcinoma human cell lines, as assessed by Northern blot, RT-PCR, FACS analysis and ganciclovir-mediated toxicity assay, and no expression was found in lentivirally transduced normal human hepatocytes. Altogether, these results demonstrate the possibility to use a lentivirally transduced expression unit containing the rat alpha-fetoprotein promoter to restrict the HSV-TK-mediated induced GCV sensitivity to human hepatocarcinoma cells.

Antitumoral effects of recombinant adenovirus YKL-1001, conditionally replicating in alpha-fetoprotein-producing human liver cancer cells

Selectively replicating recombinant adenovirus has emerged as a novel strategy for the treatment of incurable human cancers. One of the major characteristics of hepatocellular carcinoma is the transcriptional reactivation of alpha-fetoprotein (AFP). In this study, we evaluated the liver cancer-specific oncolytic potential of E1B 55kDa-deleted recombinant adenovirus (YKL-1001), which retained other E1 genes driven by the AFP promoter. Transient transfection study using luciferase indicated the selective activation of the AFP promoter only in human liver cancer cells secreting AFP (HepG2, Hep3B). YKL-1001 induced both cytopathic effects exclusively in AFP-positive liver cancer cells and the growth inhibition of pre-established Hep3B xenografts. Finally, hematoxylin-eosin staining and the immunohistochemistry to the adenoviral hexon showed a large distributed necrotic area and this implied a wide spread of YKL-1001. Therefore, the present study demonstrated that YKL-1001 holds significant promise as an oncolytic agent for hepatocellular carcinoma.

Gene therapy of hepatocellular carcinoma and gastrointestinal tumors

Primary liver cancer and liver metastases from gastrointestinal tumors lack effective therapy. Gene therapy is a promising therapeutic approach and is based on the introduction of genetic material into cells to generate a curative biological effect. Adenoviral vectors can very efficiently transduce a wide variety of malignant epithelial cells both in vitro and in vivo. A variety of gene therapy-based anticancer strategies have been effective in animal tumor models, including replacement of tumor suppressor genes, selective activation of prodrugs, genetic immunotherapy, and antiangiogenic actions. Enzymes used for genetic activation include viral thymidine kinase (tk), which may activate nucleoside analogs such as ganciclovir. We and others have demonstrated the efficacy of the tk/ganciclovir system in the treatment of hepatocellular carcinoma and metastatic colorectal cancer in experimental models. Also, this strategy can be safely applied to patients with liver tumors. Interleukin-12 (IL-12) is among the most potent cytokines in stimulating antitumor immunity. In models of primary and metastatic liver cancer we showed that intratumoral administration of recombinant adenovirus encoding IL-12 activates natural killer cells, induces specific antitumor immunity, and displays a powerful antiangiogenic effect, resulting in tumor regression. There is a synergistic effect with the gene transfer of the chemokine IP-10. Also, intratumoral injection of either dendritic cells transfected ex vivo with recombinant adenovirus encoding IL-12 (Ad.IL-12) or an adenovirus coding for the CD40 ligand have shown an intense antitumor effect against experimental colorectal cancer. In summary, a variety of gene therapy strategies have been effective against animal models of gastrointestinal tumors. Clinical trials should determine whether human patients can be treated safely and effectively by such strategies.

Practical management of hepatocellular carcinoma

Primary hepatocellular carcinoma (HCC) is one of the ten commonest tumours in the world and occurs mainly in patients with cirrhosis. To date, in Western countries, curative treatment options include partial liver resection or liver transplantation in selected patients with small tumours. Unfortunately, most patients are detected with non-resectable or non-transplantable HCC due to disease extension, hepatic dysfunction or comorbid factors. These patients may benefit from local ablative therapy, such as percutaneous ethanol injection or radiofrequency ablation, with curative intent in patients with small tumours. In advanced HCC chemoembolization has a high response rate, but there is no clear evidence of a survival benefit. In this review we discuss practical considerations in the treatment of HCC and propose an algorithm for the selection of different treatment modalities.

Prognosis of a large cohort of patients with hepatocellular carcinoma in a single European centre

BACKGROUND/AIM

Only a few follow up data are available for patients with hepatocellular carcinoma (HCC) in Europe and the USA. Therefore, we analysed all HCC patients admitted to our hospital between 1988 and 1999.

METHODS

We documented aetiology, stage (HCC: Okuda and UICC classifications, liver cirrhosis: Child-Pugh score), and diagnostic and therapeutic measures of 281 consecutive HCC patients. Survival time was calculated as a function of staging and therapy.

RESULTS

Cirrhosis was diagnosed in all patients. Seventy-two patients underwent liver resection, 28 liver transplantation, 31 transarterial chemoembolization and 14 percutaneous ethanol injection. One hundred and thirty-six patients received no treatment. The Okuda and the Child-Pugh classification predicted a significant decrease of median survival time, whereas the UICC classification was less powerful.

CONCLUSIONS

HCC occurred only in patients with liver cirrhosis. Survival time correlated with therapy (or no therapy) and with the Child-Pugh Score. In European patients the Okuda classification is superior to the UICC classification and should be compared to novel classification systems.

Non-surgical treatment of hepatocellular carcinoma

Primary hepatocellular cancer is a disease with a poor prognosis for which there is little consensus on treatment and a paucity of comparative trials. The coexistence of cancer with cirrhosis complicates treatment, and also confers a high risk for the development of further tumours. Surgery, either by hepatic resection or orthotopic liver transplantation, is only a feasible option in a minority of patients. This article surveys the non-surgical approaches to the treatment of hepatocellular cancers-local ablation techniques, arterial embolization with and without chemotherapy, conventional chemotherapy and hormonal modulation, and targeted and external irradiation.

Retrovirus-mediated gene therapy for hepatocellular carcinoma with reversely oriented therapeutic gene expression regulated by alpha-fetoprotein enhancer/promoter

In the present study, to achieve more selective and efficient therapeutic gene expression in hepatoma cells, we compared the therapeutic efficacies of the retroviral vectors expressing the herpes simplex virus thymidine kinase (HSV-tk) gene by the alpha-fetoprotein (AFP) enhancer/promoter in the forward (LNAFE0.3TK) and reverse (LN[AFE0.3TK]R) orientation to the vector long terminal repeats. By Northern blotting, the level of the HSV-tk mRNA in LN[AFE0.3TK]R-infected HepG2 human hepatoma cells was much higher than that in LNAFE0.3TK-infected cells. Consistent with this, LN[AFE0.3TK]R infection into HepG2 cells caused a greater cytotoxicity by ganciclovir exposure together with a stronger bystander effect than LNAFE0.3TK infection. In an animal model, intratumorous injection of LN[AFE0.3TK]R with ganciclovir treatment resulted in pronounced growth inhibition of HepG2 tumor. Thus, the reversely oriented therapeutic gene expression under the control of AFP enhancer/promoter is a possible candidate for the retrovirus-mediated gene therapy for hepatocellular carcinoma.