Antiangiogenic activity of BAI1 in vivo: implications for gene therapy of human glioblastomas.

Glioblastomas are the most common primary brain tumors in adults. These tumors exhibit a high degree of vascularization, and malignant progression from astrocytoma to glioblastoma is often accompanied by increased angiogenesis and the upregulation of vascular endothelial growth factor and its receptors. In this study, we investigated the in vivo antiangiogenic and antitumor effects of brain-specific angiogenesis inhibitor 1 (BAI1) using human glioblastoma cell lines. Glioblastoma cells were transduced with an adenoviral vector encoding BAI1 (AdBAI1), and Northern and Western blot analyses, respectively, demonstrated BAI1 mRNA and protein expression in the transduced tumor cells. Using an in vivo neovascularization assay, we found that angiogenesis surrounding AdBAI1-transduced glioblastoma cells transplanted into transparent skinfold chambers of SCID mice was significantly impaired compared to control treated cells. Additionally, in vivo inoculation with AdBAI1 of established subcutaneous or intracerebral transplanted tumors significantly impaired tumor growth and promoted increased mouse survival. Morphologically, the tumors exhibited signs of impaired angiogenesis, such as extensive necrosis and reduced intratumoral vascular density. Taken together, these data strongly indicate that BAI1 may be an excellent gene therapy candidate for the treatment of brain tumors, especially human glioblastomas.

Haematopoietic progenitor cells from the common marmoset as targets of gene transduction by retroviral and adenoviral vectors.

To establish a new non-human primate model for human cytokine and gene therapy, we characterized lymphocytes and haematopoietic progenitor cells of the small New World monkey, the common marmoset. We first assessed the reactions of marmoset bone marrow (BM) and peripheral blood (PB) cells to mouse anti-human monoclonal antibodies (mAbs) for the purpose of isolating marmoset lymphocytes and haematopoietic progenitor cells. Both cell fractions stained with CD4 and CD8 mAbs were identified as lymphocytes by cell proliferation assay and morphological examination. Myeloid-specific mAbs such as CD14 and CD33 did not react with marmoset BM and PB cells. No available CD34 and c-kit mAbs could be used to purify the marmoset haematopoietic progenitor cells. Furthermore, we studied the in vitro transduction of the bacterial beta-galactosidase (LacZ) gene into CFU-GM derived from marmoset BM using retroviral and adenoviral vectors. The transduction efficiency was increased by using a mixed culture system consisting of marmoset BM stromal cells and retroviral producer cells. It was also possible to transduce LacZ gene into marmoset haematopoietic progenitor cells with adenoviral vectors as well as retroviral vectors. The percentage of adenovirally transduced LacZ-positive clusters was 15% at day 4 (multiplicity of infection=200), but only 1-2% at day 14. The differential use of viral vector systems is to be recommended in targeting different diseases. Our results suggested that marmoset BM progenitor cells were available to examine the transduction efficiency of various viral vectors in vitro.

MHC (major histocompatibility complex)-DRB genes and polymorphisms in common marmoset.

A New World monkey, the common marmoset (Callithrix jacchus), will be used as a preclinical animal model to study the feasibility of cell and gene therapy targeting immunological and hematological disorders. For elucidating the immunogenetic background of common marmoset to further studies, in the present study, polymorphisms of MHC-DRB genes in this species were examined. Twenty-one Caja-DRB exon 2 alleles, including seven new ones, were detected by means of subcloning and the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) methods followed by nucleotide sequencing. Based on the alignment of these allele sequences, we designed two pairs of specific primers and established a PCR-SSCP method for DNA-based histocompatibility typing of the common marmoset. According to the family segregation data and phylogenetic analyses, we presumed that Caja-DRB alleles could be classified into five different loci. Southern blotting analysis also supported the existence of multiple DRB loci. The patterns of nucleotide substitutions suggests that positive selection operates in the antigen-recognition sites of Caja-DRB genes.

Progress reports on immune gene therapy for stage IV renal cell cancer using lethally irradiated granulocyte-macrophage colony-stimulating factor-transduced autologous renal cancer cells.

There is no effective treatment for patients with stage IV renal cell cancer (RCC), although the introduction of new therapy is imminent. Cancer gene therapy is currently considered to be one of the most promising therapeutic modalities in the field of cancer treatment. Based on the results of animal studies, vaccination using autologous granulocyte-macrophage colony-stimulating factor-transduced renal cancer cells appears promising. Before initiating a clinical study using an ex vivo gene-transduced autologous cell vaccine-based immunogene therapy for RCC in Japan, in 1992 we initially planned a Japanese version of a clinical protocol in collaboration with a US group. In 1993, the original protocol was refined. We performed five preclinical qualification studies using RCC nephrectomy specimens from patients in 1997, and the results showed that preparation of RCC cells for autologous vaccines at the Clinical Cell Technology Facility, Research Hospital of the Institute of Medical Science, University of Tokyo, was feasible. Subsequently in August 1998, the Ministry of Health and Welfare and the Ministry of Education, Science, Culture, and Sport approved our clinical protocol. We have recruited two patients with stage IV RCC to our study so far. Here we report the background to the initiation of cancer gene therapy in Japan.

TCR-Vbeta repertoire analysis with RT-PCR was useful for the early detection of pulmonary relapsed T-cell lymphoma after autologous peripheral blood stem cell transplantation.

Pulmonary recurrence of malignant lymphoma is a rare event after stem cell transplantation. We report here a 45-year-old male who was successfully diagnosed with relapsed pulmonary T-cell lymphoma using an RT-PCR method. Clonal expansion of T cells expressing identical TCR V-D-J junction size (Vbeta5-Jbeta1.5) was demonstrated in lymphocyte groups obtained from both bronchoalveolar lavage fluid at relapse, and paraffin embedded lymph node samples resected when he was first diagnosed with angioimmunoblastic T-cell lymphoma. This method provided evidence to diagnose relapsed pulmonary angioimmunoblastic T-cell lymphoma in its early phase.

The common marmoset as a target preclinical primate model for cytokine and gene therapy studies.

Nonhuman primate models are useful to evaluate the safety and efficacy of new therapeutic modalities, including gene therapy, before the inititation of clinical trials in humans. With the aim of establishing safe and effective approaches to therapeutic gene transfer, we have been focusing on a small New World monkey, the common marmoset, as a target preclinical model. This animal is relatively inexpensive and easy to breed in limited space. First, we characterized marmoset blood and bone marrow progenitor cells (BMPCs) and showed that human cytokines were effective to maintain and stimulate in culture. We then examined their susceptibility to transduction by retroviral vectors. In a mixed culture system containing both marmoset stromal cells and retroviral producer cells, the transduction efficiency into BMPCs and peripheral blood progenitor cells (PBPCs) was 12% to 24%. A series of marmosets then underwent transplantation with autologous PBPCs transduced with a retroviral vector carrying the multidrug resistance 1 gene (MDR1) and were followed for the persistence of these cells in vivo. Proviral DNA was detectable by polymerase chain reaction (PCR) in peripheral blood granulocytes and lymphocytes in the recipients of gene transduced progenitors up to 400 days posttransplantation. To examine the function of the MDR1 gene in vivo, recipient maromsets were challenged with docetaxel, an MDR effluxed drug, yet the overall level of gene transfer attained in vivo (<1% in peripheral blood granulocytes) was not sufficient to prevent the neutropenia induced by docetaxel treatment. Using this model, we safely and easily performed a series of in vivo studies in our small animal center. Our results show that this small nonhuman primate, the common marmoset, is a useful model for the evaluation of gene transfer methods targeting hematopoietic stem cells.

Superiority of interleukin-12-transduced murine lung cancer cells to GM-CSF or B7-1 (CD80) transfectants for therapeutic antitumor immunity in syngeneic immunocompetent mice.

Interleukin-12 (IL-12) is a heterodimeric cytokine that consists of p40 and p35 subunits. IL-12 has been regarded as a potent inducer of host antitumor immunity through interferon-gamma (IFN-gamma) production and development of Th1 helper T cells from Th0 cells. Here, we demonstrate the immunomodulatory actions of an IL-12-transduced murine lung cancer cell line, Lewis lung carcinoma (LLC) (LLC/IL12) cells, in syngeneic C57BL/6 mice. We also report on their therapeutic potency. Three LLC/IL12 cells producing different levels of IL-12 were cloned and found to have diminished tumorigenicity in C57BL/6 mice depending on their level of IL-12 production. In vivo depletion assay demonstrated that the loss of tumorigenicity of LLC/IL12 depended on both CD4+ and CD8+ T cells, and that natural killer (NK) cells were involved, especially in the early phase of immunity. The strong systemic antitumor immunity against challenge with wild type LLC (LLC/wt) cells was also induced by LLC/IL12 cells. The systemic antitumor memory was found to be dependent mainly on the CD4+ T-cell subset. 51Cr-release assay revealed that the killer activity consisted of a specific killer activity directed at the parental LLC/wt cells and a nonspecific killer activity directed at both LLC/wt and syngeneic EL-4 thymoma cells. In addition, LLC/IL12 apparently had a much stronger antitumor effect against the established LLC/wt tumor than LLC transduced with B7-1 or GM-CSF cDNA. IL-12 can be considered an efficient candidate molecule for immunogene therapy for lung cancer in this experimental system.

Vaccine effect of granulocyte-macrophage colony-stimulating factor or CD80 gene-transduced murine hematopoietic tumor cells and their cooperative enhancement of antitumor immunity.

To develop immunogene therapy targeting minimal residual hematopoietic tumor cells in patients, we transduced murine GM-CSF or CD80 gene into murine WEHI 3B myelomonocytic leukemia and EL-4 thymic lymphoma cells using retroviral vectors and evaluated their effects on inducing antitumor responses in syngeneic host mice. Subcutaneously injected GM-CSF- and CD80 gene-transduced WEHI 3B (GMCSF/WEHI/3.2 or CD80/WEHI/1.8, respectively) cells lost their original tumorigenicity in immunocompetent syngeneic mice. Results from tumor inoculation experiments using athymic nude mice suggested that the rejection of GMCSF/WEHI/3.2 in immunocompetent mice depended fully on T cells and that of CD80/WEHI 1.8 depended partly on T cells and partly on NK cells. In both WEHI 3B and EL-4 models, irradiated GM-CSF gene-transduced cells provided strong immuno-protection against wild-type cells, but irradiated CD80 gene-transduced cells did not. A remarkably high cooperative effect was obtained when irradiated GMCSF/EL-4 and CD80/EL-4 were inoculated together. These results suggested that the tumor vaccine effect is efficiently enhanced by GM-CSF gene transduction and CD80 gene transduction induces some protective antitumor immunity in co-operation with GM-CSF gene transduction.

GM-CSF and B7-1 (CD80) co-stimulatory signals co-operate in the induction of effective anti-tumor immunity in syngeneic mice.

B7-1 (CD80) co-stimulatory molecule gene-transduced Lewis lung carcinoma (LLC) cells (LLC/B7 cells) resulted in remarkable loss of tumorigenicity in syngeneic C57BL/6 mice (87.5% rejection) compared to B7-negative, wild-type LLC (LLC/wt) cells (0% rejection). However, mice that had rejected LLC/B7 cells developed almost no systemic immunity protective against challenge with wild-type tumor cells after 4 weeks (11.8% rejection). Enhancement of MHC class I (H-2Kb) expression of LLC/B7 cells with in vitro interferon-gamma treatment did not result in enhancement of protective immunity. In vivo depletion assay revealed that abrogation of tumorigenicity in LLC/B7 depended on CD8+ T cells but not on CD4+ T cells. However, vaccination of C57BL/6 mice with irradiated LLC cells transduced with GM-CSF (LLC/GM) led to the induction of potent, specific immunity against challenge with the LLC/wt cells after 2 weeks (80.8% rejection). Next, we established a double transfectant of LLC cells expressing both B7-1 and GM-CSF (LLC/GM + B7). The tumorigenicity of these clonal cells was also remarkably suppressed (90% rejection) to the same degree as LLC/B7, whereas that of LLC/GM was not suppressed (0% rejection). Interestingly, mice that had rejected LLC/GM+B7 cells developed enhanced protective immunity against challenge with LLC/wt cells after 4 weeks (55.6% rejection) compared to the results of LLC/B7 cells (11.8%). To evaluate whether co-expression of GM-CSF and B7-1 enabled the tumor cells to activate cytotoxic T cells more efficiently than B7-1 alone, we performed an in vitro killing assay. We found that immunization with LLC/GM+B7 cells resulted in a 3-fold stronger cytotoxic response than that with LLC/B7. Our data indicate that co-transfection of the B7-1 co-stimulatory molecule and GM-CSF genes may be more effective for the induction of stronger protective immunity in this experimental system.

Transduction of LacZ gene into leukemia cells using viral vectors of retrovirus and adenovirus.

Recent developments in gene therapy techniques enable us to introduce new genetic information into hematopoietic cells. Among the various techniques, we focused on two viral vector systems, one using a retrovirus and the other an adenovirus. By using an adenoviral vector we could transduce and highly express bacterial beta-galactosidase (LacZ) gene under the control of the CAG (cytomegalovirus enhancer with chicken beta-actin promoter) promoter in various hematopoietic cells, although the expression persisted for only two weeks. The retroviral vector (MFG) could transduce the LacZ gene into hematopoietic cells almost as well as the adenoviral vector using the repetitive infection protocol. The retroviral system could maintain the expression of transduced cells quite longer than the adenoviral system. Differential use of these two vector systems may be helpful for the gene transduction into various kinds of hematopoietic cells (Lin et al., manuscript in preparation).