Comparative morphology and tumourigenicity of human hepatocellular carcinoma cell lines in athymic rats and mice

Hepatic Artery Embolization Enhances Expression of Programmed Cell Death 1 Ligand 1 in an Orthotopic Rat Hepatocellular Carcinoma Model: In Vivo and in Vitro Experimentation

PURPOSE

To evaluate the effects of hepatic artery embolization (HAE) on the expression of programmed cell death 1 ligand 1 (PD-L1) in an orthotopic rat hepatocellular carcinoma (HCC) model.

MATERIALS AND METHODS

A rat HCC model was established in Sprague-Dawley rats with the RH7777 cell line. Six animals each were assigned to receive HAE or sham treatment. Liver tissues were harvested 24 h after the procedure. Immunohistochemistry (IHC) was used to compare expression of PD-L1 and hypoxia-inducible factor (HIF)-1α in the intratumoral and peritumoral regions and normal liver tissue. In vitro cell culture study was performed for 24 h under normoxic and hypoxic conditions, and protein expression of PD-L1 and HIF-1α and the effects of HIF-1α inhibitors were assessed.

RESULTS

IHC showed that PD-L1- and HIF-1α-positive areas were significantly larger in the HAE group vs the sham group in intratumoral (P = .006 and P < .001, respectively) and peritumoral regions (both P < .001). The expression of PD-L1 positively correlated with HIF-1α expression in the intratumoral region (r² = 0.551; P < .001). In vitro cell culture study revealed that protein expression of PD-L1 and HIF-1α were significantly higher when cells were incubated under hypoxic vs normoxic conditions (P = .028 and P = .010, respectively). PD-L1 expression was suppressed significantly when the HIF-1α inhibitor rapamycin was added to the culture medium (P = .024).

CONCLUSIONS

HAE enhances intratumoral and peritumoral PD-L1 expression in a rat HCC model. The HIF-1α pathway is a possible mechanism underlying increased intratumoral PD-L1 expression after HAE.

Multimodal imaging of a humanized orthotopic model of hepatocellular carcinoma in immunodeficient mice

The development of multimodal strategies for the treatment of hepatocellular carcinoma requires tractable animal models allowing for advanced in vivo imaging. Here, we characterize an orthotopic hepatocellular carcinoma model based on the injection of luciferase-expressing human hepatoma Huh-7 (Huh-7-Luc) cells in immunodeficient mice. Luciferase allows for an easy repeated monitoring of tumor growth by in vivo bioluminescence. The intrahepatic injection was more efficient than intrasplenic or intraportal injection in terms of survival, rate of orthotopic engraftment, and easiness. A positive correlation between luciferase activity and tumor size, evaluated by Magnetic Resonance Imaging, allowed to define the endpoint value for animal experimentation with this model. Response to standard of care, sorafenib or doxorubicin, were similar to those previously reported in the literature, with however a strong toxicity of doxorubicin. Tumor vascularization was visible by histology seven days after Huh-7-Luc transplantation and robustly developed at day 14 and day 21. The model was used to explore different imaging modalities, including microtomography, probe-based confocal laser endomicroscopy, full-field optical coherence tomography, and ultrasound imaging. Tumor engraftment was similar after echo-guided intrahepatic injection as after laparotomy. Collectively, this orthotopic hepatocellular carcinoma model enables the in vivo evaluation of chemotherapeutic and surgical approaches using multimodal imaging.

Piper and Vismia species from Colombian Amazonia differentially affect cell proliferation of hepatocarcinoma cells

There is an increasing interest to identify plant-derived natural products with antitumor activities. In this work, we have studied the effects of aqueous leaf extracts from Amazonian Vismia and Piper species on human hepatocarcinoma cell toxicity. Results showed that, depending on the cell type, the plants displayed differential effects; thus, Vismia baccifera induced the selective killing of HepG2, while increasing cell growth of PLC-PRF and SK-HEP-1. In contrast, these two last cell lines were sensitive to the toxicity by Piper krukoffii and Piper putumayoense, while the Piperaceae did not affect HepG2 growth. All the extracts induced cytotoxicity to rat hepatoma McA-RH7777, but were innocuous (V. baccifera at concentrations < 75 µg/mL) or even protected cells from basal death (P. putumayoense) in primary cultures of rat hepatocytes. In every case, cytotoxicity was accompanied by an intracellular accumulation of reactive oxygen species (ROS). These results provide evidence for the anticancer activities of the studied plants on specific cell lines and suggest that cell killing could be mediated by ROS, thus involving mechanisms independent of the plants free radical scavenging activities. Results also support the use of these extracts of the Vismia and Piper genera with opposite effects as a model system to study the mechanisms of the antitumoral activity against different types of hepatocarcinoma.

Design and development of a robotized system coupled to µCT imaging for intratumoral drug evaluation in a HCC mouse model

Hepatocellular carcinoma (HCC) is one of the most common cancer related deaths worldwide. One of the main challenges in cancer treatment is drug delivery to target cancer cells specifically. Preclinical evaluation of intratumoral drugs in orthotopic liver cancer mouse models is difficult, as percutaneous injection hardly can be precisely performed manually. In the present study we have characterized a hepatoma model developing a single tumor nodule by implantation of Hep55.1C cells in the liver of syngeneic C57BL/6J mice. Tumor evolution was followed up by µCT imaging, and at the histological and molecular levels. This orthotopic, poorly differentiated mouse HCC model expressing fibrosis, inflammation and cancer markers was used to assess the efficacy of drugs. We took advantage of the high precision of a previously developed robotized system for automated, image-guided intratumoral needle insertion, to administer every week in the tumor of the Hep55.1C mouse model. A significant tumor growth inhibition was observed using our robotized system, whereas manual intraperitoneal administration had no effect, by comparison to untreated control mice.

FXR controls the tumor suppressor NDRG2 and FXR agonists reduce liver tumor growth and metastasis in an orthotopic mouse xenograft model

The farnesoid X receptor (FXR) is expressed predominantly in tissues exposed to high levels of bile acids and controls bile acid and lipid homeostasis. FXR^−/− mice develop hepatocellular carcinoma (HCC) and show an increased prevalence for intestinal malignancies, suggesting a role of FXR as a tumor suppressor in enterohepatic tissues. The N-myc downstream-regulated gene 2 (NDRG2) has been recognized as a tumor suppressor gene, which is downregulated in human hepatocellular carcinoma, colorectal carcinoma and many other malignancies.

We show reduced NDRG2 mRNA in livers of FXR^−/− mice compared to wild type mice and both, FXR and NDRG2 mRNAs, are reduced in human HCC compared to normal liver. Gene reporter assays and Chromatin Immunoprecipitation data support that FXR directly controls NDRG2 transcription via IR1-type element(s) identified in the first introns of the human, mouse and rat NDRG2 genes. NDRG2 mRNA was induced by non-steroidal FXR agonists in livers of mice and the magnitude of induction of NDRG2 mRNA in three different human hepatoma cell lines was increased when ectopically expressing human FXR. Growth and metastasis of SK-Hep-1 cells was strongly reduced by non-steroidal FXR agonists in an orthotopic liver xenograft tumor model. Ectopic expression of FXR in SK-Hep1 cells reduced tumor growth and metastasis potential of corresponding cells and increased the anti-tumor efficacy of FXR agonists, which may be partly mediated via increased NDRG2 expression. FXR agonists may show a potential in the prevention and/or treatment of human hepatocellular carcinoma, a devastating malignancy with increasing prevalence and limited therapeutic options.

Reliable establishment of human sarcoma xenografts in the nude rat

Purpose. The ability to establish consistent human tumor xenografts in experimental animals is a crucial part of preclinical investigations.The goal of this study was to develop a method of establishing a human tumor xenograft in the leg of a nude rat for evaluation of new surgical and molecular methods of treatments of human extremity sarcoma.

Methods and results. Initial attempts to produce sarcoma nodules by subcutaneous injection of a human leiomyosarcoma tumor cell suspension (SKLMS-1) resulted in tumor nodule formation in only four of 10 sites (40%).The xenograft method was modified to include younger nude rats of a different source and substrain (HSD:rnu/rnu, 5–9 weeks old), treated with 500 cGy whole-body irradiation, and the transplantation of tumor cells or small tumor fragments which had been embedded in Matrigel.These changes improved the tumor take rate per site to 52/52 (100%).Tumor nodules demonstrated rapid and progressive growth and histological features consistent with the original human sarcoma.

Discussion. Successful human leiomyosarcoma establishment in these nude rats permits the investigation of sarcoma biology and treatment with surgical procedures for which a mouse model would be inadequate. In this study we identified modifications in technique which enhanced the xenografting of a leiomyosarcoma cell line in nude rats; these techniques may increase tumor take rates for other tumor types as well.

Identification of SOX4 target genes using phylogenetic footprinting-based prediction from expression microarrays suggests that overexpression of SOX4 potentiates metastasis in hepatocellular carcinoma

A comprehensive microarray analysis of hepatocellular carcinoma (HCC) revealed distinct synexpression patterns during intrahepatic metastasis. Recent evidence has demonstrated that synexpression group member genes are likely to be regulated by master control gene(s). Here we investigate the functions and gene regulation of the transcription factor SOX4 in intrahepatic metastatic HCC. SOX4 is important in tumor metastasis as RNAi knockdown reduces tumor cell migration, invasion, in vivo tumorigenesis and metastasis. A multifaceted approach integrating gene profiling, binding site computation and empirical verification by chromatin immunoprecipitation and gene ablation refined the consensus SOX4 binding motif and identified 32 binding loci in 31 genes with high confidence. RNAi knockdown of two SOX4 target genes, neuropilin 1 and semaphorin 3C, drastically reduced cell migration activity in HCC cell lines suggesting that SOX4 exerts some of its action via regulation of these two downstream targets. The discovery of 31 previously unidentified targets expands our knowledge of how SOX4 modulates HCC progression and implies a range of novel SOX4 functions. This integrated approach sets a paradigm whereby a subset of member genes from a synexpression group can be regulated by one master control gene and this is exemplified by SOX4 and advanced HCC.

In vitro and in vivo suppression of growth of hepatocellular carcinoma cells by novel traditional Chinese medicine-platinum anti-cancer agents

Protein phosphatase 2A (PP2A) is a new target for platinum (Pt)-based cancer chemotherapeutic agents. A series of novel Pt complexes containing demethylcantharidin, a modified component of a traditional Chinese medicine (TCM), [Pt(C8H8O5)(NH2R)2] 1-5 have been shown to inhibit PP2A both in its purified form and in cell homogenates. In this study, the potential efficacy of compounds 1-5 in suppressing the growth of PP2A-highly expressed liver cancer was evaluated. The in vitro anti-proliferative activity of compounds 1-5 was investigated in human hepatocellular carcinoma (HCC) cell lines using the MTT assay. Compounds 1-5 were about 2-20 and 20-200 times more potent than cisplatin and carboplatin, respectively, in SK-Hep1 and HepG2 cells. The in vivo anti-tumor efficacies of 1-5 were evaluated in a s.c. inoculated SK-Hep1 xenograft model in nude mice. Compounds 1-5 demonstrated definite in vivo activity (giving rise to an optimal %T/C as low as 14.5%) without inducing undue toxicity, contrasting the lack of activity of cisplatin and carboplatin. In a cisplatin-resistant model established in vivo in human HCC, compounds 1-5 could still elicit the same level of tumor growth suppression as in the control tumors, demonstrating the circumvention of cisplatin cross-resistance. An acute toxicity study in ICR mice showed that compounds 1-5 are not nephrotoxic at LD10. The high potency of the novel TCM-Pt compounds against liver cancer and the minimal toxicity suggest that they have significant potential to be developed into useful Pt-based anti-tumor drugs.

A hepatocellular carcinoma cell line producing mature hepatitis B viral particles

Current in vitro models for hepatitis B virus (HBV) are based on human hepatoblastoma cell lines transfected with HBV genome. The objective of this work was to develop an in vitro, hepatocellular carcinoma (HCC)-based system supporting HBV full replication and producing mature viral particles. The FLC4 human HCC cell line was stably transfected with a plasmid carrying a head-to-tail dimer of the adwHBV genome. One of the clones, FLC4A10II, exhibited prolonged expression of HBV, as was demonstrated by secreted levels of HBsAg, HBeAg, and HBV DNA in the culture medium of the growing cells. Furthermore, the cells produced HBV particles that were detected by a cesium chloride density gradient performed on the culture medium. Analysis by Southern blot revealed that HBV DNA has integrated into the FLC4A10II cell genome. The presence of HBV in the FLC4A10II cells did not cause alterations in cell morphology and the cells continued to resemble mature hepatocytes. They do exhibit a high mitotic activity. The new HBV stably transfected cell line, FLC4A10II, can serve as an important tool for further exploration of HBV host-pathogen interaction, viral life cycle, and for assessing new antiviral agents.

Inducing oral immune regulation of hepatitis B virus envelope proteins suppresses the growth of hepatocellular carcinoma in mice

BACKGROUND

Hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) expresses hepatitis B surface antigen (HBsAg) on its cell surface, and this may serve as a tumor-associated antigen. It was shown previously that adoptive transfer of immunity against HBsAg facilitates the suppression of experimental human HCC-expressing HBsAg in athymic mice. The authors recently showed that it was possible to augment the anti-HBV immune response through induction of oral immune regulation for HBV-associated antigens. The objective of this study was to evaluate the effect of oral immune regulation for HBV antigens on the growth of HBsAg-expressing HCC.

METHODS

Recipient athymic Balb/c mice were irradiated sublethally and injected with 10(7) human hepatoma cells followed by the adoptive transfer of 2 x 10(6) splenocytes from donor mice. Four groups of donor Balb/c mice were studied: Two groups were immune modulated through oral administration of HBV antigens (HBsAg, PreS1, and Pre S2) or bovine serum albumin (BSA). Two control groups were immunized for HBsAg and fed HBV antigens or BSA. Recipient mice were followed for tumor volume and serum alpha-fetoprotein (aFP) levels. The humoral immune response was determined by measuring serum HBs antibodies. HBV specific T-cell immune modulation was assessed in vitro by HBV specific T-cell proliferation and interferon gamma (IFNgamma) ELISPOT assays as well as cytokine expression by reverse transcriptase-polymerse chain reaction assays.

RESULTS

The adoptive transfer of orally immune modulated HBV splenocytes induced complete tumor suppression in recipient mice compared with control mice transplanted with nonimmune modulated cells (BSA), which showed significant tumor growth (serum aFP levels were 3.5 ng/mL and 2320.0 ng/mL, respectively). Control mice transplanted with anti-HBs immunized cells (with or without oral immune modulation) manifested similar tumor suppression (3.5 ng/mL and 0.5 ng/mL, respectively). Immunoregulation for HBV antigens augmented the HBV specific T-cell immune response, as manifested by an increase in HBV specific T-cell proliferation and IFNgamma ELISPOT assays in mice orally immune regulated with HBV proteins compared with naïve mice. Tumor suppression was mediated through increased IFNgamma production in immune regulated and immunized mice.

CONCLUSIONS

The induction of oral immune regulation for HBV antigens modulated the antitumor immune response, thus suppressing the growth of HCC in mice. This effect was mediated by the enhancement of anti-HBV specific T-cell immunity.

Induction of immune tolerance toward tumor-associated-antigens enables growth of human hepatoma in mice

Adoptive transfer of immunity against hepatitis B surface antigen (HBsAg) was previously shown to facilitate suppression of experimental human hepatocellular carcinoma (HCC) expressing HBsAg in athymic mice. We have shown that oral tolerance induces antigen-specific immune suppression of HBsAg by feeding hepatitis B virus (HBV) antigens. In the present study we evaluated the effect of oral tolerance induction toward HBV or HCC antigens on the growth of experimental HCC-expressing HBsAg in mice. Tolerance induction was induced in mice by 5 oral feedings of 1 microg HBV antigens or HCC-extracted proteins (50 microg protein) before vaccination with recombinant HBsAg. Splenocytes (2 x 10(6)) from these mice were transferred to sublethally irradiated athymic BALB/c mice previously transplanted subcutaneously with 10(7) human hepatoma Hep3B cells. Adoptive transfer of splenocytes immunized toward HBsAg prevented tumor growth. At 4 weeks after splenocyte transplantation, tumor volume and serum alpha-fetoprotein (AFP) levels in athymic mice transplanted with splenocytes immunized to HBsAg were undetectable as compared with 1,048 +/- 738 mm(3) and 2,500 +/- 1,431 ng/ml in recipients of naïve splenocytes (p < 0.0001). Mice receiving splenocytes tolerized toward Hep3B cells, as manifested by reduced serum HBs antibody levels, reduced HBV-specific stimulation index and reduced HBV-specific-IFN gamma spot-forming cells, had early tumor growth evident by elevated AFP serum levels, weight loss and mortality, which were suppressed at 6 weeks. Mice transplanted with splenocytes tolerized toward HBV antigens did not have direct evidence of tumor growth. Induction of oral tolerance toward HCC-extracted proteins enabled transient tumor growth in this model. This effect was mediated through downregulation of the anti-HBV immune response.

In vitro and in vivo suppression of growth of hepatocellular carcinoma cells by albendazole

Tubulin protein is a major target of drug molecules, and consequently, tubulin inhibitors have attracted great attention as antimitotic antitumor agents for chemotherapeutic use. It has been shown that, the benzimidazole carbamate group of antiparasitics including albendazole act by inhibiting tubulin polymerization. In this study, albendazole was tested in culture against a range of human, rat and mice hepatocellular carcinoma (HCC) cells and in vivo against human SKHEP-1 tumor growth in nude mice. Albendazole induced a dose-dependent inhibition of [(3)H]thymidine incorporation in all cell lines examined and a dramatic decline in cell numbers in SKHEP-1 cells. The inhibitory effect of albendazole was evident at the 100 nM concentration and at 1000 nM, proliferation in all cell lines examined was inhibited by more than 80%, while, proliferation of HepG2, Hep3B and SKHEP-1 were suppressed by more than 90%, compared to control. Cell cycle analysis revealed that, depending on the dose employed, albendazole can arrest SKHEP-1 cells at both G0-G1 (250 nM) and G2-M (1000 nM) phases of the cycle. Albendazole treatment (300 mg/kg per day oral for 20 days) of nude mice inoculated subcutaneously with SKHEP-1, led to profound suppression of tumor growth. Immunohistochemical analysis of these tumors revealed that compared to control, those treated with albendazole have lower growth fractions. These findings demonstrate that albendazole strongly suppresses both in vitro and in vivo proliferation of HCC cells.

Downregulation of a tumor promotion immune response via induction of oral tolerance towards tumor-associated-antigens: can we 'eat the tumor'?

The mechanism by which hepatocellular carcinoma (HCC) develops and the role of the hepatitis B virus (HBV) in inducing tumors, are not yet well understood. Patients persistently infected with HBV tend to have a defective immune response against the virus, which fails to clear the virus and also induces liver injury. This defective response may also have an inducible effect on the virus and on cells that express HBV antigens, as well as play a role in the growth of neoplasm. It is possible that one of the mechanisms of tumor growth is related to a deviant immune response towards viral or tumor associated antigens. We describe two responses against the tumor. A 'good' response that would suppress the tumor and a 'bad' response that would promote it and theorize that the net balance between 'bad' and 'good' responses of the immune system towards a cancerous cell and/or antigen will predict whether a tumor grows or is suppressed. Oral tolerance involves the induction of immunological hyporesponsiveness towards specific antigens. It was shown that oral tolerance induces antigen-specific immune suppression towards tumor-associated-antigens by feeding of HBV or other tumor proteins. We hypothesize that induction of immune tolerance towards tumor-associated antigens will suppress the immune response towards these antigens, thus reducing the 'bad' response. The proposed new treatment strategy would redirect the focus from augmenting anti-tumor immune responses to inducing host tolerance towards the tumor.

In vitro and in vivo inhibition of liver cancer cells by 1,25-dihydroxyvitamin D3

Inhibitory effects of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) on the proliferation of a variety of cancer cell lines have been extensively reported. We have studied the effect of 1,25-(OH)2D3 (10(-11)-10(-6) M) on the proliferation of a number of human and rat liver cancer cell lines. Additionally, the effect of 1,25-(OH)2D3 (0.02-0.5 microg/kg per day) on the rate of growth of liver cancer cell line xenografts in nude mice was also investigated. In vitro, proliferation of Hep-3B, PLC/PRF/5, and SKHEP-1 cells was significantly inhibited by 1,25-(OH)2D3, while HTC and Novikoff cells were more resistant to the inhibitory effects of the drug. In vivo, treatment of SKHEP-1 tumor bearing nude mice with different doses of 1,25-(OH)2D3 significantly retarded tumor growth without the development of hypercalcemia.

A long-term hepatitis B viremia model generated by transplanting nontumorigenic immortalized human hepatocytes in Rag-2-deficient mice

Development of new therapies for human hepatitis B virus infection (HBV) would be greatly facilitated by the availability of a suitable small-animal model for HBV virus production in vivo. To develop a murine model for HBV production, we established an immortalized, cloned liver cell line by transferring the Simian Virus 40 Large T-Antigen into primary human hepatocytes. These cells were stably transfected with a full-length HBV genome to generate a clone that expresses HBV genes and replicates HBV. The HBV-producing cells were transplanted into the livers of mice with combined immunodeficiency (Rag-2 deficient) by intrasplenic injection. Survival of the engrafted human hepatocytes was shown in several ways: fluorescent in situ hybridization (FISH) with a human-chromosome-specific DNA probe (human alpha satellite), dot-blot hybridization of the genomic DNA extracted from liver biopsy specimens with a human-specific Alu repetitive DNA probe, Blur-8, as well as with an HBV DNA probe, and secretion of human proteins into plasma. Histological examination of mouse liver up to 8 months following human cell transplant shows completely normal architecture. Determination of plasma HBV DNA levels indicated that engrafted cells secreted 3x10(7) to 3x10(8) virions per mL into the blood, and HBsAg was detected in plasma. This new murine model of HBV viremia should be useful for in vivo HBV studies.

Altered regulation of Src tyrosine kinase by transforming growth factor beta1 in a human hepatoma cell line

Transforming growth factor betas (TGF-betas) are the potent growth inhibitors for various cell types. Certain transformed cells, however, show poor response to TGF-beta-induced growth inhibition, which contributes to their uncontrolled proliferation. Recently, we have reported that TGF-beta1 induces degradation of activated Src tyrosine kinase in rat fibroblasts. To elucidate the alteration in TGF-beta signaling pathway in tumor cells that cannot respond to the cytokine, we compared the effects of TGF-beta1 on Src kinase in two human hepatoma cell lines, TGF-beta1-insensitive Mahlavu cells and TGF-beta1-sensitive HepG2 cells. TGF-beta1 decreased Src kinase activity in HepG2 cells, but increased cellular Src levels and Src kinase activity in Mahlavu cells. Co-incubation of Mahlavu cells with TGF-beta1 and 12-O-tetradecanoyl phorbol 13-acetate (TPA) decreased Src protein levels and Src kinase activity, inducing TGF-beta1 sensitivity. TGF-beta1 induced tyrosine dephosphorylation of Ras guanosine triphosphatase-activating protein (Ras-GAP) and Ras inactivation in HepG2 cells, but induced Ras-GAP phosphorylation and Ras activation in Mahlavu cells. The Src kinase inhibitor abolished the increase of Src kinase activity in TGF-beta1-treated Mahlavu cells, and induced TGF-beta1 sensitivity. These findings suggest that regulation of Src kinase by TGF-beta1 is altered in Mahlavu cells. The altered regulation of Src may contribute to TGF-beta1 insensitivity in this cell line, at least in part through activation of Ras.

Engraftment of human kidney tissue in rat radiation chimera: I. A new model of human kidney allograft rejection

BACKGROUND

We have recently shown that lethally irradiated normal strains of mice and rats, reconstituted with bone marrow from severe combined immune deficiency (SCID) mice, can be engrafted with human peripheral blood mononuclear cells (PBMC).

METHODS

The feasibility of transplanting human renal tissue under the kidney capsule of the SCID/Lewis and SCID/nude radiation chimera and the effects of intraperitoneal infusion of allogeneic human PBMC on the human renal implants were investigated by histology, electron microscopy, immunohistochemistry, and fluorescence-activated cell sorter analysis.

RESULTS

Sequential evaluation of the human renal implants from 10 days to 2 months after transplantation showed that human parenchymal elements survive in the implants up to 2 months after transplantation. The overall architecture of the transplanted kidney tissue and the normal structure of individual cells in the glomeruli and tubuli were preserved. Infusion of allogeneic human PBMC after kidney implantation resulted in patchy cellular infiltrates, composed mainly of activated human T cells, and led to prompt rejection of the human renal tissue, whereas no signs of inflammation were observed in human renal implants of chimeric rats that did not receive human PBMC. Treatment with OKT3 antibody, anti-human CD25 antibody, or CTLA4Ig fusion protein in vivo ameliorated the rejection process.

CONCLUSIONS

Human adult kidney fragments transplanted into SCID-like rats transiently retain competent parenchymal structures. When these grafts are combined with allogeneic human PBMC, acute cellular rejection develops. We suggest that this chimeric model might be useful for the investigation of the effects of experimental manipulation on the kinetics of the inflammatory response during human renal allograft rejection.

Suppression of human hepatoma in mice through adoptive transfer of immunity to the hepatitis B surface antigen

BACKGROUND/AIMS

Adoptive transfer of immunity against hepatitis B surface antigen (HBsAg) has previously been shown to occur in mice and humans through transplantation of bone marrow cells from donors immunized against HBsAg (anti-HBs) to non-immune recipients. In the present study we evaluated the effect of adoptive transfer of immunity to HBsAg on the growth of HbsAg-secreting hepatocellular carcinoma (HCC) xenografts in athymic mice.

METHODS

Immunocompetent mice were immunized with recombinant HBsAg. Bone marrow cells from anti-HBs+ mice were injected intravenously to irradiated athymic Balb/c mice which had been previously transplanted subcutaneously with Hep3B human hepatoma cells. Treatment groups included mice receiving bone marrow transplantation from HBV-immunized (anti-HBs positive) and non-immunized (anti-HBs negative) donors.

RESULTS

At 9 weeks post bone marrow transplantation, tumor volume and serum alpha-fetoprotein levels in athymic mice receiving HBV-immune bone marrow cells were 11.5 mm3 and 363 ng/ml, respectively, as compared to 1579 mm3 and 19,000 ng/ml, in recipients of non-immune bone marrow transplantation (p<0.005). T-cell depletion of antiHBs+ immune bone marrow prior to transplantation decreased the anti-tumor effect but did not abolish it. A mild nonspecific, bone marrow-derived, graft versus tumor effect was observed in mice transplanted with human hepatoma cells that do not express HBsAg.

CONCLUSIONS

Adoptive transfer of immunity to HBV facilitates suppression of experimental human HCC expressing HBsAg. This effect is the result of a combination of specific anti-viral surface antigen effect and a nonspecific graft versus tumor effect.

Evaluation of the potent anti-hepatitis B virus agent (-) cis-5-fluoro-1-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine in a novel in vivo model

A murine model was developed to investigate the in vivo activity of anti-hepatitis B virus (HBV) agents. Mice with subcutaneous tumors of HBV-producing 2.2.15 cells showed reductions in levels of HBV in serum and in intracellular levels of HBV when the mice were orally dosed with (-) cis-5-fluoro-1-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine (FTC). No effects on tumor size or alpha-fetoprotein levels were observed. FTC can selectively inhibit HBV replication at nontoxic doses.

Adoptive transfer of immunity to hepatitis B virus in mice by bone marrow transplantation from immune donors

Recipients of allogeneic bone marrow transplantation are immunosuppressed as a result of their primary disease and by myeloablative therapy. Such patients are dependent on multiple blood products and are at risk for hepatitis B virus infection. Active immunization against hepatitis B in the immediate pre- and post-transplant periods is ineffective, presumably because of decreased T cell-dependent B-cell responses. This study was designed to evaluate, in a mouse model system, the transfer of immunity against hepatitis B to bone marrow transplant recipients through immunization of bone marrow donors against hepatitis B before transplantation. Bone marrow donor BALB/c mice were immunized with a recombinant hepatitis B vaccine. Seroconversion to HBs antibody occurred within 4 wk of primary immunization, and antibody levels in treated donor mice rose above 300 mIU/ml after a single booster injection. Bone marrow recipient mice, conditioned by sublethal irradiation, were injected intravenously with bone marrow cells obtained from syngeneic HBs antibody-positive immune donors. Antibody was detected in 10% of bone marrow recipients within 30 days of transplantation and in 56% 1 mo after a booster injection that led to a secondary rise in HBs antibody. Adoptive transfer of immunity to hepatitis B also occurred after transplantation of T cell-depleted bone marrow cells from hepatitis B-immune donors, albeit at a lower HBs antibody level. These results indicate that immunity to hepatitis B can be transferred in mice by bone marrow transplantation from hepatitis B-immune donors to immunosuppressed recipients.(ABSTRACT TRUNCATED AT 250 WORDS)

SK HEP-1: A human cell line of endothelial origin

SK-HEP-1 is an immortal, human cell line derived from the ascitic fluid of a patient with adenocarcinoma of the liver. We have determined that these cells are of endothelial origin. Despite the location of the tumor from which SK HEP-1 was derived, the cell line does not have properties of hepatocytes. Northern blot analysis of total cellular RNA shows no messenger RNA for the hepatic-specific proteins albumin, alpha-fibrinogen, or gamma-fibrinogen. Endothelial characteristics are seen by transmission electron microscopy. These features include numerous pinocytotic vesicles, electron dense granules consistent with Weibel-Palade bodies, and abundant intermediate filaments, identified immunocytochemically as vimentin. Cultures grown on plastic dishes grow in bundles of polygonal to spindle-shaped cells. Proteins characteristic for endothelial cells are identified by immunocytochemistry. Addition of basement membrane material (Matrigel) or type I collagen to the cultures induces these cells to organize into a tubular network.

HLA-class-I and -class-II expression on renal tumor xenografts and the relation to sensitivity for alpha-IFN, gamma-IFN and TNF

In this study we evaluated the usefulness of the histocompatibility leucocyte antigen (HLA) class-I and class-II expression on renal-cell carcinoma (RCC) xenografts as predictive markers for response to cytokine therapy. Eight different RCC xenografts growing in BALBC nu/nu mice were treated with 0.5 or 5.0 ng/g recombinant human alpha- or gamma-interferon (IFN), or 500 ng/g recombinant human tumor necrosis factor (TNF). Modulation of HLA class-I, -II expression was evaluated immunohistochemically using the monoclonal antibodies (MAbs) W6.32 and B8.11.2 and at the mRNA level using the plasmids pDP001 and DR alpha 120. HLA class-I expression in all lines was upregulated by alpha- and gamma-IFN and was highest in the high-IFN-dose-treated tumors. TNF also stimulated HLA-class-I expression and up-regulated class-I expression still further when combined with IFN. Highest up-regulation of HLA-class-I in all tumors was measured in the alpha-IFN-5.0/TNF-500-ng/g-treated mice, although this was not necessarily the treatment regimen resulting in the most pronounced effect on tumor growth. Hence, maximum upregulation of class-I antigens at a given regimen was not always indicative for the highest achievable anti-tumor effect. HLA-class-II expression which was present on only 3 of the untreated tumors was up-regulated by both alpha and gamma-IFN. TNF itself did not up-regulate class-II expression but enhanced the class-II expression on the alpha-IFN-treated tumors but not on the gamma-IFN-treated tumors. Irrespective of the basic expression level, inducibility of both HLA-class-I and -class-II antigens appear to be correlated to the direct effects on growth of renal-tumor xenografts towards alpha-IFN, gamma-IFN and TNF. Modulation of HLA antigens was studied in the nude mouse, hence T-cell-mediated effector mechanisms cannot explain the good correlation between inducibility and response. Nonetheless, our studies indicate that the extent of modulation of HLA-class-I and -II can serve as predictive marker for response to cytokine therapy, which may serve as a valuable criterion for inclusion of patients in cytokine treatment regimens.