研究者詳細 - 戸田　正博

論文 - 戸田　正博

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Identification of glioma-specific RFX4-E and -F isoforms and humoral immune response in patients

Matsushita Hirokazu, Uenaka Akiko, Ono Toshiro, Hasegawa Kosei, Sato Shuichiro, Koizumi Fumihito, Nakagawa Kazuhiko, Toda Masahiro, Shingo Tetsuro, Ichikawa Tomotsugu, Noguchi Yuji, Tamiya Takashi, Furuta Tomohisa, Kawase Takeshi, Date Isao, Nakayama Eiichi

Cancer Science 96 （ 11 ） 801 - 809 2005年11月

ISSN 1347-9032

For regulatory factor X4 (RFX4), two alternatively spliced variants, RFX4-A and -B, were reported in the testis. In this study, we identified transcript variants RFX4-C, -D, -E, and -F, and demonstrated by reverse transcription-polymerase chain reaction (RT-PCR) that RFX4-A, -B and -C mRNAs were expressed only in the testis, and RFX4-D mRNA was expressed only in normal brain tissues. In tumors, RFX4-E and -F in addition to RFX4-D mRNA were expressed in gliomas by rapid amplification of cDNA ends and RT-PCR analyses. Expression of RFX4 mRNA was not observed in other tumors, such as lung, esophageal, stomach, colon or liver cancers. Quantitative real-time RT-PCR using common primer pairs detecting all of the variant transcripts showed high expression in normal testis, low expression in the brain (1% compared to the expression in testis), and overexpression in 17 of 61 gliomas (28%). Western blot analysis using DC28 monoclonal antibody (mAb) produced against recombinant RFX4-D C-terminus protein showed expression of RFX4-A and -C proteins, but not RFX4-B protein, in the testis, and expression of RFX4-D protein in the brain. Moreover, expression of RFX4-E and -F proteins, but not RFX4-D protein, was observed in gliomas. Immunohistochemistry analysis using DC28 mAb showed positive staining in the nuclei of spermatocytes in the testis and glioma cells. Antibody against RFX4 was detected in the sera of 3 of 58 (5%) glioma patients by enzyme-linked immunosorbent assay, suggesting the immunogenicity of RFX4-E and -F proteins in glioma patients. © Japanese Cancer Association.

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Gene therapy for brain tumors using herpes simplex virus vector

Toda Masahiro

Nippon rinsho. Japanese journal of clinical medicine 63 Suppl 9 510 - 514 2005年

ISSN 0047-1852

Identification of an epigenetically silenced gene, RFX1, in human glioma cells using restriction landmark genomic scanning

Ohashi Yohei, Ueda Masakazu, Kawase Takeshi, Kawakami Yutaka, Toda Masahiro

Oncogene 23 （ 47 ） 7772 - 7779 2004年10月

ISSN 0950-9232

To identify the CpG islands differentially methylated in human glioma, we performed restriction landmark genomic scanning with a CpG methylation-sensitive enzyme. We found 12 spots, the intensity of which was entirely lost or decreased in both the human glioma tissues examined as compared with that in matched normal lymphocytes, indicating aberrant methylation of these CpG islands in gliomas. The expression of RFX1, one of the genes associated with the methylated CpG islands, was frequently decreased in human glioma cell lines and tissues. We also demonstrated that the isolated CpG island located in the seventh intron of the RFX1 gene had enhancer activity and was hypermethylated in all of the glioma tissues and cell lines analysed, but not in normal brains or lymphocytes. Treatment of glioma cells with a demethylating agent, 5-azacytidine, resulted in the expression of RFX1, indicating that the silencing of the RFX1 gene may be attributable to its methylation. RFX1 has been implicated in transcriptional downregulation of the proto-oncogene c-myc. By expression of the RFX1 gene, the cellular proliferative activity of glioma cells was suppressed. Taken together, these results suggest that the RFX1 gene may be epigenetically silenced in human gliomas and involved in glioma tumorigenesis.

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Identification of human tumor antigens and its implications for diagnosis and treatment of cancer

Kawakami Yutaka, Fujita Tomonobu, Matsuzaki Yuriko, Sakurai Toshiharu, Tsukamoto Makoto, Toda Masahiro, Sumimoto Hidetoshi

Cancer Science 95 （ 10 ） 784 - 791 2004年10月

ISSN 1347-9032

Human tumor antigens recognized by T cells have been identified by means of various molecular biological and immunological methods, including cDNA expression cloning with patients' T cells and antibodies, cDNA subtraction using RDA and PCR differential display, systematic gene analysis such as DNA sequencing, CGH, DNA chip/microarray and SAGE, in vitro T cell induction and immunization of HLA transgenic mice. The identification of human tumor antigens has led to a better understanding of the nature of tumor antigens, anti-tumor immune responses in patients before and after immunotherapy, and tumor escape mechanisms. The information obtained from these researches has enabled us to develop and improve immunotherapy by attempting to overcome the identified problems, including intrinsically low immunogenicity of tumor antigens and several escape mechanisms, such as regulatory T cell induction. The existence of immunogenic unique antigens derived from genetic alterations in tumor cells, and the varied immunogenicity of shared tumor antigens among patients due to differing expression in tumor cells and immunoreactivity of patients, indicates that individualized immunotherapy should ideally be performed. The identified antigens will also be useful for development of diagnostic methods and molecular targeting therapy for cancer.

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Implantation of Dendritic Cells in Injured Adult Spinal Cord Results in Activation of Endogenous Neural Stem/Progenitor Cells Leading to De Novo Neurogenesis and Functional Recovery

Mikami Yuji, Okano Hideyuki, Sakaguchi Masanori, Nakamura Masaya, Shimazaki Takuya, Okano Hirotaka James, Kawakami Yutaka, Toyama Yoshiaki, Toda Masahiro

Journal of Neuroscience Research 76 （ 4 ） 453 - 465 2004年05月

ISSN 0360-4012

We report a treatment for spinal cord injury involving implantation of dendritic cells (DCs), which act as antigen-presenting cells in the immune system. The novel mechanisms underlying this treatment produce functional recovery. Among the immune cells tested, DCs showed the strongest activity inducing proliferation and survival of neural stem/progenitor cells (NSPCs) in vitro. Furthermore, in DC-implanted adult mice, endogenous NSPCs in the injured spinal cord were activated for mitotic de novo neurogenesis. These DCs produced neurotrophin-3 and activated endogenous microglia in the injured spinal cord. Behavioral analysis revealed the locomotor functions of DC-implanted mice to have recovered significantly as compared to those of control mice. Our results suggest that DC-implantation exerts trophic effects, including activation of endogenous NSPCs, leading to repair of the injured adult spinal cord. © 2004 Wiley-Liss, Inc.

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Augmentation of Antitumor Immune Responses by Multiple Intratumoral Inoculations of Replication-Conditional HSV and Interleukin-12

Iizuka Yukihiko, Suzuki Ayuko, Kawakami Yutaka, Toda Masahiro

Journal of Immunotherapy 27 （ 2 ） 92 - 98 2004年03月

ISSN 1524-9557

Intratumoral inoculation with a herpes simplex virus (HSV) mutant, G207, as an in situ cancer vaccine has been shown to inhibit tumor growth by inducing tumor-specific immune responses. Here, as a step toward the clinical application of this therapeutic approach, we evaluated different protocols for enhancing the antitumor effect. First, in a bilaterally established tumor model with CT26 colon carcinoma, we demonstrated that multiple intratumoral inoculations with G207 induced a greater antitumor effect on both the inoculated and distant tumors than did 1 or 2 inoculations. Second, to boost this antitumor effect, we developed 2 strategies: multiple in situ cancer vaccines with G207 in combination with systemic administration of recombinant interleukin-12 (rIL-12) (G207/systemic rIL-12) or local administration of rIL-12 (G207/local rIL-12). The antitumor effects in both the inoculated and distant tumors by the combined treatments were significantly greater than by either G207 or rIL- 12 treatment alone. G207/systemic rIL-12 and G207/local rIL-12 mediated the complete regression of both the inoculated and distant tumors in 67% and 79% of the animals, respectively. These results indicate that multiple intratumoral inoculations of G207 and systemic or local rIL- 12 administration work synergistically to facilitate tumor regression and that this combination of treatments may have potential for treating cancer metastasis.

Identification of a human glioma antigen, SOX6, recognized by patients' sera

Ueda Ryo, Iizuka Yukihiko, Yoshida Kazunari, Kawase Takeshi, Kawakami Yutaka, Toda Masahiro

Oncogene 23 （ 7 ） 1420 - 1427 2004年02月

ISSN 0950-9232

To identify tumor antigens for glioma, a human testis cDNA library was screened by serological identification of antigens by recombinant expression cloning with sera from glioma patients. In this screening, the most frequently isolated antigen was SOX6, an Sry-related high-mobility group (HMG) box-containing gene. SOX6 is a transcriptional factor that is specifically expressed in the developing central nervous system and in the early stages of chondrogenesis in mouse embryos. IgG antibodies against SOX6 were detected in sera from 12 of 36 glioma patients (33.3%), 0 of 14 patients with other brain disease (0%), and one of 54 other cancer patients (1.9%). In sera from 37 healthy individuals, no IgG responses against SOX6 were detected, except in an elderly female. Furthermore, Western blot and ELISA analyses with sera from glioma patients revealed that the DNA-binding domain, the HMG box of SOX6, might be a dominant epitope of IgGs against SOX6. RT-PCR and Northern blot analysis revealed that the SOX6 gene was more highly expressed in glioma tissues than in normal adult tissues, except testis. Western blot analysis with an anti-SOX6 antibody demonstrated that the SOX6 protein was expressed in glioma tissues, but not in normal adult brain tissue. Immunohistochemical analysis with the anti-SOX6 antibody showed that all the glioma tissues analysed expressed SOX6 in tumor cells, but only a few SOX6-positive cells were detected in non-neoplastic tissues from the cerebral cortex. In summary, these results indicate that the developmentally regulated transcription factor SOX6 is aberrantly expressed in glioma and specifically recognized by IgGs from glioma patients' sera.

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Expression of a transcriptional factor, SOX6, in human gliomas

Ueda Ryo, Yoshida Kazunari, Kawakami Yutaka, Kawase Takeshi, Toda Masahiro

Brain Tumor Pathology 21 （ 1 ） 35 - 38 2004年

ISSN 1433-7398

By screening a human testis cDNA library with glioma patients' sera, we isolated a transcriptional factor, SOX6. Here, we analyzed SOX6 expression in gliomas having a range of malignancy grades using immunostaining. Murine Sox6 is a transcriptional factor that is specifically expressed in the developing central nervous system and in the early stages of chondrogenesis in mouse embryos. The reverse transcription-polymerase chain reaction (RT-PCR) revealed that the SOX6 gene was more highly expressed in glioma tissues and fetal brain than in normal adult brain and other cancer cells, except melanoma cells. Immunohistochemical analysis with the anti-SOX6 antibody showed that all the glioma tissues analyzed (14 glioblastomas, 14 anaplastic astrocytomas, 3 anaplastic oligoastrocytomas, 5 diffuse astrocytomas, 1 oligodendroglioma, and 1 pilocytic astrocytoma) expressed SOX6 in tumor cells, but only a few SOX6-positive cells were detected in nonneoplastic tissues from the cerebral cortex. These results indicate that the developmentally regulated transcription factor SOX6 may be a potential diagnostic marker for gliomas.

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Immunohistochemical analysis of SOX6 expression in human brain tumors

Ueda Ryo, Yoshida Kazunari, Kawakami Yutaka, Kawase Takeshi, Toda Masahiro

Brain Tumor Pathology 21 （ 3 ） 117 - 120 2004年

ISSN 1433-7398

We previously demonstrated that the developmentally regulated gene, SOX6, is strongly expressed in glioma cells and in the fetal brain, but only faintly in the normal adult brain. Recent studies have indicated that brain tumor cells may share antigens, signaling systems, and behavior with neural stem/progenitor cells. To test the validity of this proposition, we analyzed the expression of SOX6 in various human central nervous system (CNS) tumors. Immunohistochemical analysis revealed that astrocytic and oligodendroglial tumors expressed SOX6; neuronal-glial cell tumors (central neurocytoma) and embryonal tumors (medulloblastoma), which arise from multipotential stem cell precursors, also showed a high intensity of SOX6 staining. In contrast, ependymal tumors (ependymoma and subependymoma), meningioma, and schwannoma, which are all well differentiated tumors, showed either no staining or only faint staining for SOX6. These results suggest that SOX6 may be expressed in bipotential or multipotential cells capable of neuronal and glial differentiation, but not in fully differentiated cells. SOX6 may be a useful marker for the diagnosis of tumors arising from immature bipotential cells that may differentiate into neuronal and glial cells.

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Immuno-viral therapy as a new approach for the treatment of brain tumors

Toda Masahiro

Drug News and Perspectives 16 （ 4 ） 223 - 229 2003年05月

ISSN 0214-0934

The central nervous system (CNS) has been considered an immunologically privileged site; however, recent evidence suggests that activated T cells cross the intact blood-brain barrier and that a series of immunological events is initiated when T cells recognize CNS antigens. Therefore, brain tumors might be selectively eliminated by T cells activated with antigens specific for the tumors. Using a conditionally replicating herpes simplex virus-1 (HSV-1) mutant, G207, we developed a novel therapeutic approach for metastatic brain tumors that combines viral therapy with immunotherapy. G207 replicates selectively within tumor cells and causes tumor cell destruction without local or systemic toxicity, because its replication in normal cells is highly attenuated. Furthermore, the inoculation of tumors outside the CNS with G207 induces systemic immune responses not only to HSV but also to tumor antigens. In our strategy, in which both the metastatic brain tumor and the primary tumor outside the CNS are inoculated with G207, the HSV-infected brain tumor can be eliminated by the combined effects of the direct oncolysis and the induced anti-HSV and antitumor T cells. Recently, the safety of directly inoculating the human brain with G207 has been shown. These results indicate that our therapeutic approach using G207 may hold promise for the treatment of metastatic brain tumors. © 2003 Prous Science. All rights reserved.

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Immuno-viral therapy of brain tumors by combination of viral therapy with cancer vaccination using a replication-conditional HSV

Toda Masahiro, Iizuka Yukihiko, Kawase Takeshi, Uyemura Keiichi, Kawakami Yutaka

Cancer Gene Therapy 9 （ 4 ） 356 - 364 2002年

ISSN 0929-1903

Here we developed an effective therapeutic approach using a replication-conditional mutant of herpes simplex virus (HSV), G207, for the treatment of metastatic tumors in the immunologically privileged central nervous system. An experimental model of brain metastasis was developed using BALB/c mice that harbored both intracranial (i.c.) and subcutaneous (s.c.) mouse CT26 colon adenocarcinoma tumors. Intratumoral injections of G207 into s.c. tumors elicited cytotoxic T-cell responses not only to HSV but also to a tumor antigen; however, only a limited antitumor effect was observed on metastatic brain tumors. To improve this antitumor effect, G207 was also injected into the brain tumor. After intratumoral injections of G207 into both i.c. and s.c. CT26 tumors, a significant antitumor effect was observed in the metastatic brain tumors. This therapeutic efficacy was absent in athymic mice, indicating that the antitumor effect could be mediated by T cells. Cytotoxic T-cell responses to HSV and the tumor antigen were induced by injections of G207 into i.c. and s.c. CT26 tumors. These results suggest that HSV-infected brain tumors may be efficiently eliminated by the induced anti-HSV T cells as well as by antitumor T cells. Therefore, this strategy of immuno-viral therapy, involving direct viral oncolytic activities and inducing antitumor and antiviral immune responses, may be useful for the treatment of tumors in the immunologically privileged central nervous system.

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In situ cancer vaccination with a replication-conditional HSV for the treatment of liver metastasis of colon cancer

Endo Takashi, Toda Masahiro, Watanabe Masahiko, Iizuka Yukihiko, Kubota Tetsuro, Kitajima Masaki, Kawakami Yutaka

Cancer Gene Therapy 9 （ 2 ） 142 - 148 2002年

ISSN 0929-1903

In this study, we investigated the therapeutic efficacy of a replication-conditional mutant HSV, G207, for the treatment of liver metastasis of colon carcinoma. Three liver metastasis models in syngeneic BALB/c mice were developed: (i) splenic injection, (ii) splenic and subcutaneous (s.c.) injection, and (iii) orthotopic implantation of CT26 colon carcinoma. In the splenic injection model, G207 was injected into the established splenic tumor on day 7. In the splenic and s.c. injection model, G207 were injected into the established s.c. tumor on days 5 and 8. In the orthotopic implantation model, a piece of CT26 tumor tissue was transplanted onto the wall of the cecum and G207 was injected in the established cecum tumor on day 7. On day 21 or 28, animals were sacrificed and liver metastases were evaluated. In all three models in immunocompetent mice, liver metastases were significantly reduced by intratumoral inoculation with G207 compared to the control. In athymic mice, however, there was no significant therapeutic effect of intratumoral inoculation with G207 on liver metastases. Tumor-specific cytotoxic T-lymphocyte responses were induced in mice treated with G207 in the orthotopic implantation model. These results suggest that intratumoral inoculation of G207, as an in situ cancer vaccine, can be an effective approach against liver metastasis of colon cancer and the efficacy involves tumor-specific T-cell responses.

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A simple and reliable behavioral analysis of locomotor function after spinal cord injury in mice

Mikami Yuji, Toda Masahiro, Watanabe Masahiko, Nakamura Masaya, Toyama Yoshiaki, Kawakami Yutaka

Journal of Neurosurgery 97 （ 1 SUPPL. ） 142 - 147 2002年

ISSN 0022-3085

To establish a simple and reliable method to assess the behavioral function after spinal cord injury (SCI) in mice, the authors used an automated animal movement analysis system, SCANET. Two different SCI lesions were created in adult female BALB/c and C57BL/6 mice by transecting both the posterior columns and the left lateral and anterior funiculi or only the left lateral and anterior funiculi at T-8. Control mice underwent laminectomy only. The SCANET system consists of a cage equipped with two crossing sensor frames arranged at different heights, by which small (MI) and large (M2) horizontal movements and the vertical movement involved in rearing (RG) can be monitored. The authors assessed locomotor function by determining the M1, M2, and RG scores; to this end, they used the SCANET system and a previously established behavior test, the 21-point open-field Basso-Beattie-Bresnahan (BBB) Locomotor Rating Scale. The results indicated that the RG scores were significantly and consistently different between the spinal cord-injured and control mice, irrespective of the mouse strain or injury model, but that MI and M2 scores were not. Moreover, there was a statistically positive correlation between the RG score and the BBB Scale score. For the assessment of locomotor function after SCI, use of the SCANET sytem in behavioral analysis is simple and the method is highly reproducible. The analysis of vertical movement is useful for assessing the recovery of limb function in mice following thoracic hemisection.

Increase of oligodendrocyte progenitor cells after spinal cord injury

Ishii Ken, Toda Masahiro, Nakai Yoko, Asou Hiroaki, Watanabe Masahiko, Nakamura Masaya, Yato Yoshiyuki, Fujimura Yoshikazu, Kawakami Yutaka, Toyama Yoshiaki, Uyemura Keiichi

Journal of Neuroscience Research 65 （ 6 ） 500 - 507 2001年09月

ISSN 0360-4012

The reaction of oligodendrocyte progenitor cells (OPCs) after spinal cord injury (SCI) is poorly understood. In this study, we examined oligodendroglial reactions after contusion SCI in adult rats by immunohistochemistry. OPCs were identified by staining with monoclonal antibodies (mAbs) A2B5 and O4. Each of the A2B5-, O4-positive OPCs and galactocerebroside-positive oligodendrocytes dramatically increased in the lesion of the dorsal posterior funiculus. Bromodeoxyuridine (BrdU) incorporation studies showed that most O4-positive cells in the lesion were labeled with BrdU, suggesting that these OPCs were proliferative. In contrast, the expression of myelin basic protein was decreased in the lesion compared with controls that received laminectomy only. From the injured cord, OPCs were isolated by immunopanning with mAb A2B5. We observed an increased number of OPCs from the injured spinal cords compared with those isolated from controls and unoperated animals. After several days in culture, the OPCs from the lesion expressed galactocerebroside. These results suggest that OPCs are induced and can differentiate following SCI in the adult rat. © 2001 Wiley-Liss, Inc.

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Expression of the neural RNA- binding protein Musashi1 in human gliomas

Toda Masahiro, Iizuka Yukihiko, Yu Wangjie, Imai Takao, Ikeda Eiji, Yoshida Kazunari, Kawase Takeshi, Kawakami Yutaka, Okano Hideyuki, Uyemura Keiichi

GLIA 34 （ 1 ） 1 - 7 2001年

ISSN 0894-1491

Tumor cells arising from a particular tissue may exhibit the same gene expression patterns as their precursor cells. To test this proposition, we have analyzed the expression of a neural RNA-binding protein, Musashi1, in primary human central nervous system (CNS) tumors. In rodents, Musashi1 is expressed predominantly in proliferating multipotent neural precursor cells, but not in newly generated postmitotic neurons. The expression of Musashi1 is downregulated with the successive progression of neurogenesis. In normal adult human tissues, we detected low levels of Musashi1 expression in brain and testis by RT-PCR analysis. In an RNA panel of 32 cancer tissues and cell lines, elevated expression of Musashi1 was seen in all five malignant gliomas studied, in contrast to the slight expression seen in other tumor cells, including those in several melanomas and a prostate cancer. Western blot analysis showed strong Musashi1 expression in malignant gliomas compared with nonneoplastic brain tissue. Glioblastomas, the most malignant form of glioma, showed higher Musashi1 expression than less malignant gliomas by immunohistochemical analysis. Tumors with strong Musashi1 expression tended to have high proliferative activity. Thus, the expression of Musashi1 correlated with the grade of the malignancy and proliferative activity in gliomas. These results suggest that primary CNS tumors may share gene expression patterns with primitive, undifferentiated CNS cells and that Musashi1 may be a useful marker for the diagnosis of CNS tumors. © 2001 Wiley-Liss, Inc.

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Combination suicide/cytokine gene therapy as adjuvants to a defective herpes simplex virus-based cancer vaccine

Toda M., Martuza R. L., Rabkin S. D.

Gene Therapy 8 （ 4 ） 332 - 339 2001年

ISSN 0969-7128

We have used syngeneic, established bilateral subcutaneous tumor models to examine the antitumor activity of herpes simplex virus (HSV) vectors, including the induction of an immune response against non-inoculated distant tumors. In such a model with CT26 murine colon adenocarcinoma, unilateral intratumoral inoculation of replication-deficient HSV-1 tsK inhibited the growth of both the inoculated and noninoculated established tumors. To enhance this limited antitumor immune response, we generated a defective HSV vector, dvIL12-tk encoding both interleukin-12 (IL-12) and HSV thymidine kinase (TK), with tsK as the helper virus. In a 'suicide gene' strategy, ganciclovir (GCV) treatment after intratumoral inoculation of dvlacZ-tk/tsK, encoding E. coli lacZ instead of IL-12, resulted in enhanced antitumor activity. Antitumor activity was also enhanced by local expression of IL-12 from dvIL-12-tk/tsK. The combination of IL-12 cytokine therapy with GCV treatment was the most efficacious approach, with significantly greater inhibition of tumor growth than IL-12 or TK + GCV alone. These results illustrate the power of combining different cancer therapy approaches; 'suicide gene' therapy, cytokine therapy, and HSV vector infection. HSV vectors are particularly well suited to this because they can accommodate the insertion of large and multiple gene sequences.

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Tumor growth inhibition by intratumoral inoculation of defective herpes simplex virus vectors expressing granulocyte - Macrophage colony-stimulating factor

Toda Masahiro, Martuza Robert L., Rabkin Samuel D.

Molecular Therapy 2 （ 4 ） 324 - 329 2000年10月

ISSN 1525-0016

To evaluate the potential of defective herpes simplex virus (HSV) amplicon vectors as in vivo cytokine gene transfer vehicles for active immunotherapy, we generated a defective HSV vector that encodes the murine granulocyte - macrophage colony-stimulating factor (GM-CSF) gene, using a replication-defective HSV as helper virus. A variety of murine tumor cell lines were efficiently infected in vitro with the defective GM-CSF vector (dvGM), and this led to the synthesis and secretion of murine GM-CSF. In an established bilateral subcutaneous tumor model with Harding-Passey murine melanoma, unilateral intratumoral inoculation of dvGM significantly inhibited tumor growth of both the inoculated and noninoculated contralateral tumors. This tumor inhibition was dose-dependent and resulted in increased survival of the dvGM-treated mice. Inoculation of a lacZ-expressing defective vector had no effect on tumor growth. We conclude that this defective HSV vector system offers an effective method for cytokine gene delivery in vivo and that GM-CSF expression in tumors has antitumor activity.

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Comparison of Fas- versus perforin-mediated pathways of cytotoxicity in TCR- and Thy-1-activated murine T cells

Kojima Hidefumi, Toda Masahiro, Sitkovsky Michail V.

International Immunology 12 （ 3 ） 365 - 374 2000年

ISSN 0953-8178

T cell-mediated cytotoxicity can be triggered by cross-linking of TCR or Thy-1 surface proteins. While the TCR-triggered signaling initiates both perforin- and Fas ligand (FasL)-Fas-mediated mechanisms of cytotoxicity, it was not clear which mechanism was utilized by Thy-1-triggered signals and which pathway of cytotoxicity was triggered at low levels of antigen expression. It is shown that glycophosphatidylinositol-linked surface glycoprotein Thy-1 preferentially activates FasL-Fas- but not perforin-mediated cytotoxicity. This is explained by the lesser intensity of Thy-1-mediated signaling in T cells. The data suggest that Thy-1-triggered Fas-mediated cytotoxicity is completely dependent on cross-talk between Thy-1 and TCR signals since mutations in TCR-CD3 complex molecules or inhibition of tyrosine kinases or calcineurin abolished or strongly inhibited Thy-1-triggered FasL-Fas-mediated cytotoxicity. Lower concentrations of antigenic peptide or levels of cross-linking with anti-TCR-CD3 mAb are required to trigger Fas-mediated than perforin-mediated cytotoxicity by different cytotoxic T lymphocyte (CTL) lines and clones, and it is shown that cross-linking of Thy-1 is much less efficient in triggering accumulation of second messengers (intracellular Ca²⁺) than cross-linking of TCR on CTL. Taken together, these data reflect the possibility of differential activation of FasL and/or perforin pathways of cytotoxicity depending on the nature of activating stimuli and surface receptor.

Suppression of an actin-binding protein, drebrin, by antisense transfection attenuates neurite outgrowth in neuroblastoma B104 cells

Toda Masahiro, Shirao Tomoaki, Uyemura Keiichi

Developmental Brain Research 114 （ 2 ） 193 - 200 1999年05月

ISSN 0165-3806

Drebrins, actin-binding proteins, are dominantly expressed during embryogenesis and accumulated in neurite processes of postmigratory neurons. While the cytoskeletal proteins are the important factors for regulating neurite outgrowth, the cellular mechanism in neurons is still unclear. To address the role of drebrins in the neurite outgrowth, we have studied the effect of suppression of drebrin on a rat neuroblastoma B104 cell line, which constitutively expresses drebrin. Deprivation of serum or addition of gangliosides in the culture medium induced remarkable neurite outgrowth of B104 cells. We transfected B104 cells with an antisense construct of human drebrin E cDNA and found that the drebrin expression was significantly reduced in the stable antisense cell lines. In response to serum deprivation and gangliosides treatment, their ability to extend neurite processes was significantly attenuated. In contrast, the cell proliferation of the antisense transfectants was arrested by serum deprivation similar to control B104 cells. These data suggest that the drebrins are required for neurite outgrowth in neuronal cells.

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Herpes simplex virus as an in situ cancer vaccine for the induction of specific anti-tumor immunity

Toda Masahiro, Rabkin Samuel D., Kojima Hidefumi, Martuza Robert L.

Human Gene Therapy 10 （ 3 ） 385 - 393 1999年02月

ISSN 1043-0342

The success of cancer gene therapy is likely to require the targeting of multiple antitumor mechanisms. One strategy involves the use of attenuated, replication-competent virus vectors, such as herpes simplex virus type 1 (HSV-1) mutant G207, which is able to replicate in human tumor cells with resultant cell death and tumor growth inhibition, yet is nonpathogenic in normal tissue. In this study, we demonstrate that infection of established tumors with G207 also induces a highly specific systemic anti-tumor immune response. In a syngeneic, bilateral established subcutaneous tumor model, with mouse CT26 colorectal carcinoma cells in BALB/c mice or M3 melanoma cells in DBA/2 mice, unilateral intratumoral inoculation with G207 caused a significant reduction in the growth of both the inoculated and contralateral noninoculated tumors. This elicited anti-tumor response is dependent on viral infection of the tumor, as intradermal inoculation of G207 in BALB/c mice had no effect on CT26 tumor growth. Treatment of subcutaneous CT26 tumors by intratumoral inoculation of G207 induced a tumor-specific T cell response, CD8⁺ cytotoxic T lymphocyte (CTL) activity was generated that recognized a dominant 'tumor-specific' major histocompatibility complex (MHC) class I-restricted epitope (AH1) from CT26 cells. In immune-competent animals, G207 is acting as an in situ tumor vaccine. Therefore, intratumoral G207 inoculation is able to inhibit tumor growth both by local cytotoxic viral replication in tumor cells and induction of a systemic anti-tumor immune response.

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