Frequent amplification of c-myc in ground squirrel liver tumors associated with past or ongoing infection with a hepadnavirus.

Persistent infection with hepatitis B virus (HBV) is a major cause of hepatocellular carcinoma (HCC) in humans. HCC has also been observed in animals chronically infected with two other hepadnaviruses: ground squirrel hepatitis virus (GSHV) and woodchuck hepatitis virus (WHV). A distinctive feature of WHV is the early onset of woodchuck tumors, which may be correlated with a direct role of the virus as an insertional mutagen of myc genes: c-myc, N-myc, and predominantly the woodchuck N-myc2 retroposon. In the present study, we searched for integrated GSHV DNA and genetic alterations of myc genes in ground squirrel HCCs. Viral integration into host DNA was detected in only 3/14 squirrel tumors and did not result in insertional activation of myc genes, despite the presence of a squirrel locus homologous to the woodchuck N-myc2 gene. This suggests that GSHV may differ from WHV in its reduced ability to induce mutagenic integration events. However, the high frequency of c-myc amplification (6/14) observed in ground squirrel HCCs indicates that myc genes might be preferential effectors in the tumorigenic processes associated with rodent hepadnaviruses, a feature not reported so far in HBV-induced carcinogenesis. Together with previous observations, our results suggest that hepadnaviruses, despite close genetic and biological properties, may use different pathways in the genesis of liver cancer.     

Combined GM-CSF and IL-12 gene therapy synergistically suppresses the growth of orthotopic liver tumors

Immunotherapy is often effective only for small tumor burdens and, in many cases, is restricted to subcutaneous tumors. Here, we investigated the antitumor effects of combination therapy with GM-CSF and IL-12 on orthotopic liver tumors with intermediate or large tumor volumes, or on chemically-induced multifocal liver tumors in animals. Adenoviruses encoding GM-CSF or IL-12 were injected intratumorally to animals bearing transplanted tumors, or injected via intrahepatic artery in animals with primary multifocal liver tumors induced by diethylnitrosamine. Our results demonstrated that IL-12, but not GM-CSF, monotherapy displayed significant therapeutic effects, whereas combination therapy with both cytokines displayed synergistic antitumor effects not only on transplanted tumor models with intermediate or large tumor loads, but also on carcinogen-induced multifocal liver tumors. Effector cell analyses, revealed by in vivo cell subset depletion, flow cytometry analysis, and immunohistochemical staining of tumor infiltrates, indicated that NK cells were the prominent antitumor effectors for the IL-12-mediated antitumor activity, whereas CD8+ T cells, NKT cells, and macrophages were more important than NK cells in the combination therapy-mediated antitumor effects. Both IL-12 monotherapy and combination therapy could induce various types of effectors and high levels of IFN-gamma; however, the latter induced much higher levels than the former, which may explain why combination therapy is superior to IL-12 monotherapy. CONCLUSION: Combination therapy with GM-CSF and IL-12 represents a promising immunotherapy strategy for treating orthotopic, widespread liver tumors.     

Th1 cytokine-based immunotherapy for cancer

Cytokine-based immunotherapy is executed by harnessing cytokines to activate the immune system to suppress tumors. Thl-type cytokines including IL-1, IL-2, IL-12 and granulocyte-macrophage colony-stimulating factor are potent stimulators of Thl differentiation and Thl-based antitumor response. Many preclinical studies demonstrated the antitumor effects of Thl cytokines but their clinical efficacy is limited. Multiple factors influence the efficacy of immunotherapy for tumors. For instance immunosuppressive cells in the tumor microenvironment can produce inhibitory cytokines which suppress antitumor immune response. Most studies on cytokine immunotherapy focused on how to boost Thl response; many studies combined cytokine-based therapy with other treatments to reverse immunosuppression in tumor microenvironment. In addition, cytokines have pleiotropic functions and some cytokines show paradoxical activities under different settings. Better understanding the physiological and pathological functions of cytokines helps clinicians to design Thl-based cancer therapy in clinical practice.     

Integration of woodchuck hepatitis and N-myc rearrangement determine size and histologic grade of hepatic tumors

Integrations of woodchuck hepatitis virus (WHV) DNA and rearrangements of the N-myc 2 gene have been detected frequently in hepatocellular carcinoma (HCC) of Eastern woodchucks (Marmota monax) chronically infected with WHV. Fifty-five hepatocellular neoplasms and matched nontumor hepatic tissue specimens obtained postmortem from 13 chronic WHV carriers were analyzed and the frequency of WHV DNA integrations and of N-myc rearrangements compared in tumors of different size and histologic grade. Four small tumor nodules were classified histologically as adenomas and integrated sequences of WHV DNA were detected in two of the four tumor nodules. In one of the two nodules, there was evidence of N-myc rearrangement. Fifty-one neoplasms were classified as HCC. Seven were grade 1 HCCs. WHV DNA integrations were demonstrated in 43% but none had N-myc rearrangements. Twenty grade 2 HCCs had WHV DNA integrations in 80% and in 38% N-myc rearrangements were present. Twenty-four grade 3 HCCs had integrations of WHV DNA in 79% and N-myc rearrangements in 74%. In two other grade 3 HCCs, rearrangements of N-myc were detected in the absence of WHV DNA integrations. The 12 largest tumors in the series all were grade 2 or 3 HCCs, and in 83%, both WHV DNA integrations and N-myc rearrangements were demonstrated. In conclusion, molecular changes observed in this study suggest a progression of genetic alterations providing either a significant proliferative stimulation and/or a growth advantage in hepatocarcinogenesis of woodchucks with chronic WHV infection.     

Treatment of murine hepatocellular carcinoma using genetically modified cells to express interleukin-12

BACKGROUND AND AIM: The majority of patients cannot benefit from the conventional curative treatments that are currently used for hepatocellular carcinoma (HCC), which remains a world health problem. Interleukin (IL)-12 is one of the most potent anti-tumor cytokines. The aim of the present study was to examine the anti-tumor effect and toxicity of intrahepatic delivery of IL-12 using an ex vivo gene therapy approach in a murine model of HCC. METHODS: Syngenic fibroblasts or MM45T-Li HCC tumor cells were genetically modified in vitro to express IL-12 using a polycistronic TFG murine IL-12 retroviral vector (TFGmIL-12) coding for both p35 and p40 murine IL-12 subunits. Hepatocellular carcinoma was generated using direct intrahepatic inoculation of the tumor cell line into the left liver lobe of BALB/c mice. RESULTS: Direct liver expression of IL-12 by the injected genetically modified tumor cells induced a marked inhibition of tumor growth. This effect was associated with an early infiltration of macrophages, and lymphocytes forming numerous intralobular foci. There was no significant liver toxicity, as shown by normal biochemical liver tests. At a later time, the intralobular foci were rare and consisted mainly of CD4+ T cells, while CD8+ T cells were present in the lobule. Intrahepatic expression of IL-12 did not modify circulating or splenic B lymphocytes or natural killer (NK) cells. The inhibition of tumor growth was maintained in nude mice even when depleted in NK cells. Importantly, in a second model, treatment of established day 7 liver tumors in BALB/c mice using direct intra-tumor injection of syngenic fibroblasts that were genetically modified to express IL-12 significantly reduced tumor size. CONCLUSION: In conclusion, these data provide evidence that experimental HCC can be efficiently and safely treated using ex vivo IL-12 gene therapy, which seems promising for future clinical studies.     

Antiangiogenic gene therapy for hepatocellular carcinoma using angiostatin gene

Recent studies have reported that antiangiogenic gene delivery into cancer cells inhibits growth of certain tumors in vivo. Hepatocellular carcinoma (HCC) is a hypervascular cancer, and antiangiogenic gene therapy might be suitable for HCC. In the present study, we investigated the antiangiogenic effects of angiostatin gene transduction into HCC both in vitro and in vivo. Angiostatin gene was cloned into a pSecTag2B mammalian expression vector to construct pSecTag2B-ANG. pSecTag2B or pSecTag2B-ANG were transfected into an HCC cell line, PLC/PRF/5, and then stable transfectants were obtained by Zeocin selection. pSecTag2B or pSecTag2B-ANG transfection did not alter the expression of vascular endothelial growth factor (VEGF), a potent angiogenic stimulator, or pigment epithelium-derived factor (PEDF), an angiogenic inhibitor, in PLC/PRF/5 cells. However, conditioned media (CM) derived from pSecTag2B-ANG-transfected PLC/PRF/5 cells (CM-ANG) suppressed the proliferation and migration of human umbilical vein endothelial cells (HUVEC) by 35% and 50%, respectively, relative to their effects on nontransfected cells. In in vivo experiments, pSecTag2B-ANG stable transfected (CM-Mock) and nontransfected cells (CM-N) were mixed at various proportions and the mixed cells were subcutaneously implanted into athymic mice. Suppression of tumor growth was noted in mice implanted with angiostatin gene-transfected cells, and such suppression was proportional with the percentage of transfected cells. Analysis of the vascular density in these tumors showed that the tumor growth suppression effect of angiostatin gene correlated with suppression of tumor vascularity. In conclusion, antiangiogenic gene therapy using angiostatin gene is potentially suitable for the treatment of patients with HCC.     

MAGE-1基因在肝细胞性肝癌中的表达

目的探讨ＭＡＧＥ－１基因编码的肿瘤相关抗原作为肝细胞性肝癌（ＨＣＣ）主动免疫治疗攻击靶点的可能性。方法用ＲＴ－ＰＣＲ的方法检测了３９例ＨＣＣ及癌旁组织、３种人肝癌细胞株和５例非ＨＣＣ病例肝组织中ＭＡＧＥ－１基因的表达。结果ＨＣＣ癌组织中ＭＡＧＥ－１基因表达率明显高于癌分组织中的表达率,５８．９％（２／３９）对１０．３％（４／３９）,Ｐ＜００１。３种细胞株均为阳性表达。结论ＭＡＧＥ－１基因可作为主动免疫治疗的攻击靶点,以进一步研究设计新的ＨＣＣ免疫治疗策略。     

Multicentric occurrence of hepatocellular carcinoma: diagnosis and clinical significance

To evaluate current knowledge on the multicentric occurrence (MO) of hepatocellular carcinoma (HCC) and its clinical significance was the purpose of this review. The criteria for MO of HCC are defined as follows: (1) the recurrent tumor consists of well differentiated HCC occurring in a different hepatic segment from moderately or poorly differentiated preexisting HCC, (2) both the primary and recurrent tumors are well differentiated HCC, (3) the recurrent tumors contain regions of dysplastic nodules in peripheral areas and, (4) multiple HCCs, indicating the “nodule‐in‐nodule” form, in which nodules consisting of moderately or poorly differentiated HCC cells are contained in a nodule of well differentiated HCC cells. However, these criteria assume rare or no metastasis of well differentiated HCC, and are also not applicable to cases in which some HCCs of multicentric origin are rapidly dedifferentiated, presenting morphologic features of moderately or poorly differentiated tumors. Diagnostic methods, besides histopathologic methods, for determining multicentric origin in multiple HCCs in the liver, or recurrent tumor(s) of HCC, include clonal analysis of the integration pattern of hepatitis B virus (HBV) DNA in HBV carrier patients, and analysis of thep53 mutation patterns or loss of heterozygosity of chromosomal DNA. The prognosis of patients with MO of HCC after curative resection is significantly better than that of patients with intrahepatic HCC metastasis. Moreover, the Liver Cancer Study Group of Japan has reported that patients with hepatic resection for small‐sized HCCs showed higher survival rates than a nonsurgical treatment group. Consequently, HCC with MO, whether this is synchronous or metachronous, should be surgically removed as the treatment of first choice.     

Molecular targets for prevention of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in some areas of the world with an extremely poor prognosis. The major etiologic risk factors for HCC development include toxins (alcohol, aflatoxin B1), androgens and estrogens, hepatitis B virus (HBV) and hepatitis C virus (HCV) infection as well as various inherited metabolic disorders, such as alpha-1-antitrypsin deficiency and hemochromatosis. The molecular pathogenesis of HCC development is very complex and involves alterations in the structure or expression of several tumor suppressor genes, oncogenes and, possibly, mechanisms leading to a genetic instability due to mismatch repair deficiency or chromosomal instability and aneuploidy due to defective chromosomal segregation. Central to the molecular pathogenesis of HCCs are mutations of various genes and a genetic instability which in most cases result from chronic liver disease and the associated enhanced liver cell regeneration and mitotic activity. The prognosis of HCC patients is generally very poor. Most studies report a five year survival rate of less than 5% in symptomatic HCC patients. Furthermore, these tumors have been shown to be quite resistant to radio- or chemotherapy. Investigations of the natural history and clinical course of HCCs revealed long-term survival of patients only with small asymptomatic HCCs that could be treated surgically or by non-surgical interventions. Apart from exploring and refining new HCC treatment strategies, the implementation of existing and the development of novel measures to prevent HCC development are most important. Primary HCC prevention includes among others universal hepatitis B vaccination, antiviral therapy of patients with chronic hepatitis B or C, reduction of food contamination with aflatoxins, elimination of excessive alcohol etc. Also for some genetic diseases there is the potential for HCC prevention by identifying affected family members at risk, such as patients with precirrhotic hemochromatosis. Reduction of iron overload by phlebotomy has been shown to eliminate the progression hemochromatosis to liver cirrhosis and HCC. Preventive measures, therefore, should have a major impact on the incidence of HCCs in patients with acquired and inherited liver diseases. Further, the prevention of a local recurrence or the development of new HCC lesions in patients after successful surgical or non-surgical HCC treatment (secondary prevention) is of paramount importance and is expected to significantly improve disease-free and overall patient survival. Based on rapid scientific advances, molecular diagnosis, gene therapy and molecular prevention are becoming increasingly part of our patient management and will eventually complement and in part replace existing diagnostic, therapeutic and preventive strategies. Overall, this should result in a reduction of the incidence of HCCs, one of the most devastating malignancies worldwide.     

Antiangiogenic property of pigment epithelium-derived factor in hepatocellular carcinoma

Pigment epithelium-derived factor (PEDF) is one of the most powerful endogenous antiangiogenic reagents discovered to date. Its antiangiogenic potential in neoplastic disease remains unclear. In this study, we investigated antiangiogenic property of PEDF in hepatocellular carcinoma (HCC), a typical hypervascular tumor. In HCC cell lines, constitutive messenger RNA and protein expression of PEDF varied. Genomic DNA encoding the PEDF gene was the same in the cell lines examined by Southern blotting. In chemically induced hypoxic conditions, secreted PEDF protein was suppressed in contrast to elevation of vascular endothelial growth factor protein. When PEDF was overexpressed by gene transfer, proliferation and migration of endothelial cells were inhibited in conditioned media derived from all HCC cell lines. However, the serum concentration of PEDF, as measured by enzyme-linked immunosorbent assay, was decreased in patients with cirrhosis or HCC complicated by cirrhosis compared to healthy volunteers and patients with chronic hepatitis. According to the endothelial cell proliferation assay, the serum PEDF of patients with HCC had antiangiogenic activity. Moreover, intratumoral injection of a PEDF-expressing plasmid in athymic mouse models caused significant inhibition of preestablished tumor growth. In conclusion, PEDF plays a role in the angiogenic properties of HCC. Reduction of serum PEDF concentration associated with the development of chronic liver diseases may contribute to the progression of HCC. In addition, gene therapy using PEDF may provide an efficient treatment for HCC.     

Molecular targets for therapy of hepatitis B virus-induced hepatocellular carcinoma

Chronic hepatitis B virus (HBV) infection is the most frequent risk factor for development of hepatocellular carcinoma (HCC) worldwide. Studies of the molecular genetics and pathophysiology of HCC suggest that there are significant differences in the allelic imbalance, genome copy number, and gene expression patterns of HBV-induced HCC as compared to HCCs from other causes, which are presumably reflected to differences in the mode of presentation and outcomes of HBV-induced HCCs. Unique features of HBV-induced carcinogenesis include the role of HBV DNA integration in carcinogenesis and the powerful synergism between HBV and dietary aflatoxins in the pathogenesis of HCC. A more complete understanding of the biology of HBV-induced HCCs may reveal well-defined differences in the molecular pathways that regulate growth of these HCCs and allow better-targeted approaches to prevention and therapy of HBV-induced HCCs. This review will attempt to summarize the current knowledge about carcinogenic pathways in HBV-induced HCCs, review the agents currently in development for targeted therapy of HCCs, and propose potentially novel approaches to therapy of HBV-induced HCC.     

Combined Antiangiogenic and Immune Therapy of Prostate Cancer

Experimental studies of antiangiogenic or immune therapy of cancer have generated a great deal of optimism. However, the results of clinical testing of these therapies are below expectations. We hypothesized that the antitumor efficacy can be increased when immune destruction of tumor cell is combined with destruction of tumor vasculature by antiangiogenic drugs. In the present study the therapeutic efficacy of combined antiangiogenic and immune therapy has been tested against the highly aggressive, MHC class I negative murine RM1 prostate tumor. SU6668 was used as the antiangiogenic drug and recombinant murine B7.2-IgG fusion protein was used to stimulate T cell-mediated immune destruction of tumor cells. SU6668 is an inhibitor of the tyrosine kinase activity of three angiogenic receptors VEGFR2 (Flk-1/KDR), PDGFRβ and FGFR1 that play a crucial role in tumor-induced vascularization. Our studies show that B7.2-IgG treatment of mice with established RM1 prostate tumors resulted in a significant inhibition of tumor growth. Both CD4⁺ and CD8⁺ T cells were responsible for this effect. SU6668 therapy substantially inhibited tumor vascularization and tumor growth. When tumor-bearing mice were treated with SU6668 in combination with B7.2-IgG, the antitumor effects were substantially higher than in mice treated separately with SU6668 or B7.2-IgG. Prolonged treatment of mice with SU6668 did not inhibit the immunoreactivity of T lymphocytes. On the contrary, T cells from mice treated with a combination of SU6668 and B7.2-IgG showed higher proliferative responses and cytokine production following anti-CD3 stimulation than T cells of mice treated separately with these modalities. These results indicate that antiangiogenic and immune therapies using SU6668 and B7.2-IgG are compatible and manifest complementary antitumor effects. Combined antiangiogenic and immune therapy might represent a new strategy for cancer treatment.     

Adeno-associated virus-mediated expression of apolipoprotein (a) kringles suppresses hepatocellular carcinoma growth in mice

Hepatocellular carcinoma (HCC) constitutes more than 90% of all primary liver cancers. HCC is a hypervascular tumor that develops from dedifferentiation of small avascular HCC and is therefore a good target for anti-angiogenic gene therapy. Recent studies have identified apolipoprotein(a) [apo(a)] kringles LK68 and LK8 (LKs) as having a potential antiangiogenic and anti-tumor activity, and the current study evaluates the therapeutic potential of gene therapy with recombinant adeno-associated virus carrying genes encoding LKs (rAAV-LK) in the treatment of hypervascular HCC. We generated rAAV-LK to obtain persistent transgene expression in vivo, which is essential for anti-angiogenic therapy. The rAAV-produced LKs substantially inhibited proliferation and migration of human umbilical vein endothelial cells (HUVECs) in vitro, validating their anti-angiogenic potential. Intramuscular administration of rAAV-LK gave 60% to 84% suppression (P < .05) of tumor growth in mice bearing subcutaneously transplanted HCC derived from Huh-7 and Hep3B cells, respectively. Histological and immunohistochemical analyses of HCC tumor sections showed that a single administration of rAAV-LK gave rise to persistent expression of LKs that inhibited tumor angiogenesis and triggered tumor apoptosis, and, thus, significantly suppressed tumor growth. The administration of rAAV-LK provided a significant survival benefit (P < .05), and 3 of 10 rAAV-LK-treated mice were still alive without visible tumors and without clinical symptoms 188 days after treatment. In conclusion, rAAV-LK is a potential candidate for anti-angiogenic gene therapy in the treatment of HCC.     

Hepatitis-related hepatocellular carcinoma: Insights into cytokine gene polymorphisms

Hepatocellular carcinoma(HCC) is a primary liver cancer, which is one of the most prevalent cancers among humans. Many factors are involved in the liver carcinogenesis as lifestyle and environmental factors. Hepatitis virus infections are now recognized as the chief etiology of HCC; however, the precise mechanism is still enigmatic till now. The inflammation triggered by the cytokine-mediated immune response, was reported to be the closest factor of HCC development. Cytokines are immunoregulatory proteins produced by immune cells, functioning as orchestrators of the immune response. Genes of cytokines and their receptors are known to be polymorphic, which give rise to variations in their genes. These variations have a great impact on the expression levels of the secreted cytokines. Therefore, cytokine gene polymorphisms are involved in the molecular mechanisms of several diseases. This piece of work aims to shed much light on the role of cytokine gene polymorphisms as genetic host factor in hepatitis related HCC.     

Clonality of large regenerative nodules in liver cirrhosis

Abstract: The role of the large regenerative nodule (RN) in hepatocarcinogenesis is not clear, although the incidence of hepatocellular carcinoma (HCC) is high in cirrhotic liver. This study was aimed at clarifying the preneoplastic nature of large RN without atypia. We analyzed the clonality of HCCs and large RNs, ranging in size from 0.6 to 1.2 cm, of cirrhotic liver by X-linked human androgen receptor (HUMARA) gene assay, using the principle of random X chromosome methylation and inactivation in females. Eleven cases of HCC and five cases of large RN without atypia from ten female patients were selected. All HCCs, large RNs and paired non-tumorous tissue from adjacent liver were selectively microdissected from deparaffinized hematoxylin and eosin stained slides. Genomic DNA was isolated and digested with Hha I. Polymerase chain reaction (PCR) amplification of the HUMARA gene was performed using a PCR mixture containing [α-³²P]-dCTP. The PCR products were separated by gel electrophoresis and analysed by autoradiography. HUMARA was informative in nine out of ten female patients. In the informative 10 HCCs from nine patients, 9 HCCs were monoclonal and one case was polyclonal. The HCC case that showed polyclonality contained many inflammatory cells in the tumor. All of the large RNs were polyclonal. No allelic loss of chromosome 18q was present in the large RNs in constrast to the 3 out of 7 HCCs, which showed allelic deletion in chromosome 18q. We conclude that all or most of the cells composing the large RNs without atypia are polyclonal and the size of a nodule may not be important in hepatocarcinogenesis. This clonality assay may be informative for the differentiation between regenerative and preneoplastic nodules in cirrhotic liver.     

Efficient human interferon-alpha gene transfer to neuroendocrine tumor cells with long-term and stable expression

Interferon (IFN)-alpha has been used in the treatment of neuroendocrine (NE) tumors; however, the feasibility of IFN-alpha gene therapy has not been evaluated in NE tumor cells. In this study, human IFN-alpha2 (hIFN-alpha2) gene has been transferred into a NE tumor cell line BON. hIFN-alpha2-expressing BON cells were subcutaneously inoculated in nude mice. The results demonstrated that hIFN-alpha2 exerted significant antiproliferative effects on NE tumor cell lines (BON and LCC18) and other tumor cell lines (CA46 and SW480) as well as porcine aorta cell line. Furthermore, hIFN-alpha2 demonstrated its antineovascular activity in mice tumor and a direct antiangiogenic effect in chicken chorioallantoic membrane assay. hIFN-alpha2-expressing BON cells had a stable and long-term expression. Mice implanted with hIFN-alpha2-expressing BON cells showed a lower incidence, a delayed development and a significantly longer doubling time of the tumor compared to both wild-type (WT) and vector group. In addition, IFN-alpha significantly inhibited cell adhesion of WT BON cells. hIFN-alpha2-expressing BON tumors had a high level of hIFN-alpha2 protein. Finally, mice implanted with a mixture of WT and hIFN-alpha2-expressing BON cells (1:1) presented a delayed tumor development and had an even lower incidence of tumors than those implanted with hIFN-alpha2-expressing BON cells only. The doubling time of tumor was also longest in the mixture group. Our data suggest that hIFN-alpha2 gene therapy might be possible to be used as a new treatment for NE tumor patients. Further studies on the regulation of hIFN-alpha expression are needed, especially in combination with other cytokines, which could lead to a better understanding and improvements of hIFN-alpha gene therapy.