Toshihiro Imaizumi

Identification of a Gene Coding for a New Squamous Cell Carcinoma Antigen Recognized by the CTL

Peptide-based specific immunotherapy has resulted in tumor regression in some melanoma patients. However, tumor Ags and peptides for specific immunotherapy, except for treatment of melanomas, have not yet been well identified. In this study, we report a gene encoding a new squamous cell carcinoma (SCC) Ag recognized by cells of the HLA-A24-restricted and tumor-specific CTL line. This gene with 3958-bp length was transcribed from the chromosome 6q22 with six exons, and its mRNA was ubiquitously expressed in both SCCs and normal tissues, and partly expressed in adenocarcinomas. The deduced 958-aa sequence encoded by this gene showed no similarity to any known amino acid sequences. This gene product had a characteristic of an endoplasmic reticulum-resident protein. A 100-kDa protein was detected in the vast majority of SCCs from various tissues, in majority of renal cell carcinomas and brain tumors, and in about one-third of melanomas and adenocarcinomas from various organs other than the breast. In contrast, it was not expressed at all in any of the normal cells or tissues tested, including the testis and fetal liver. Three different peptides at positions 93–101, 161–169, and 899–907 of this Ag were recognized by this CTL line, and all of them induced HLA-A24-restricted and tumor-specific CTLs from PBMCs of SCC patients. Therefore, these peptides may be useful for peptide-based specific immunotherapy of HLA-A24+ patients with SCC in various organs, as well as for treatment of other cancer.

Therapeutic effect and mechanism of repetitive transcranial magnetic stimulation in Parkinson's disease

Abstract The therapeutic effect of repetitive transcranial magnetic stimulation (rTMS) on clinical performance was assessed by a double-blind study in 9 patients with Parkinsons disease (PD). Nine other patients underwent sham stimulation as controls. The modified Hoehn and Yahr (H&Y) staging scale, the Schwab and England Activities of Daily Living (ADL) scale, and the Unified Parkinsons disease rating scale (UPDRS) were used to assess changes of clinical performance. Patients were assessed prior to and following 2 months of rTMS. In addition, the mechanism of rTMS was investigated by dopamine and homovanillic acid (HVA) in the lumbar cerebrospinal fluid (CSF) of 17 patients before and after therapeutic rTMS for three or four months. rTMS was applied manually to the frontal areas 60 times per session, i. e., 30 times per side using a large circular coil, a pulse intensity of 700 V, and a frequency of 0.2 Hz. Sessions were continued once a week for 2 months. The 9 control patients showed no changes of symptoms between the initial evaluation and that after 2 months of sham rTMS. In contrast, all 9 patients receiving rTMS showed a significant decrease of the modified H&Y and UPDRS scores after 2 months, while the Schwab and England ADL Scale scores increased significantly. In the second CSF sample from patients receiving rTMS, HVA showed a significant decrease These results suggest that rTMS is beneficial for the symptoms of Parkinsons disease and that it may act via inhibition of dopaminergic systems.

Expression of the SART3 tumor-rejection antigen in brain tumors and induction of cytotoxic T lymphocytes by its peptides.

The authors recently reported on the SART3 tumor-rejection antigen, which possesses epitopes that can induce cytotoxic T lymphocytes (CTLs) in patients with epithelial cancer. To explore a new modality for treatment of patients with brain tumors, this study investigated the expression of the SART3 antigen in patients with brain tumors and the ability of SART3 peptides to induce CTLs from peripheral blood mononuclear cells (PBMCs) of these patients. The SART3 antigen was detected in the cytoplasmic fraction of all 18 glioma cell lines examined and in the majority (31 of 34; 91%) of brain tumor tissues irrespective of their histologies. It was also expressed in the nuclear fraction of all 18 glioma cell lines and in the majority (26 of 34; 76%) of brain tumor tissues. In contrast, the SART3 was not expressed in nontumorous brain tissues. Cytotoxic T lymphocytes were induced in patients with glioma by stimulation with two epitope peptides of SART3. These CTLs could eliminate glioma cells in a HLA-A24–restricted manner. Therefore, the SART3 peptides may be appropriate molecules for use in peptide-based specific immunotherapy of HLA-A24+ patients with brain tumors.

Expression of the tumor-rejection antigen SART1 in brain tumors.

We have reported a tumor‐rejection antigen, SART1259, possessing tumor epitopes capable of inducing cytotoxic T lymphocytes (CTLs) in epithelial‐cancer patients. This study investigated the expression of SART1259 antigen in brain tumors, to explore for a potential molecule for use in specific immunotherapy of patients with brain tumors. The SART1259 antigen was detected in the cytosol fraction of 13 of 18 (72%) glioma cell lines and in 12 of 34 (35%) brain‐tumor tissues, with a higher rate of expression among malignant gliomas (5/10, 50%) and schwannomas (3/4). HLA‐A24‐restricted and SART1‐specific CTLs recognized the HLA‐A24+ and SART1259+ glioma cells, and the levels of recognition correlated both with HLA‐A24‐antigen expression level and with the concentration of the SART1 peptide antigen. Therefore, the SART1259 antigen could be a target molecule for specific immunotherapy of patients with brain tumors expressing HLA‐class‐I antigens. Int. J. Cancer 83:760–764, 1999.

A case of adult-onset Alexander disease with Arg416Trp human glial fibrillary acidic protein gene mutation

Heterozygous point mutations in the coding region of the human glial fibrillary acidic protein (GFAP) gene have been reported in patients with various forms of Alexander disease (AD). We report a case of genetically confirmed adult-onset AD with palatal myoclonus, pyramidal tract signs, cerebellar signs, and marked atrophy of the medulla oblongata and spinal cord, autonomic dysfunction and heterozygous R416W GFAP mutation. Interestingly, this R416W mutation has also been reported in both infantile and juvenile forms of Alexander disease. The fact that a R416W mutation causes various types of AD suggests that clinical severities of AD are due not only to the different sites and nature of mutations in GFAP, but also to other modifying factor(s).

Sequence Analysis of Genes Encoding Rodent Homologues of the Human Tumor‐rejection Antigen SART‐1

Human SART‐1 (hSART‐1) gene encodes a 125 kD protein with a leucine‐zipper motif expressed in the nucleus of all proliferating cells, and a 43 kD protein expressed in the cytosol of most epithelial cancers. In this study, two rodent genes (rSART‐1 and mSART‐1) homologous to hSART‐1 were cloned from cDNA libraries of murine brain and a rat tumor cell line, respectively. mSART‐1 and rSART‐1 were highly homologous to hSART‐1 with 86% and 84% identity at the nucleotide level, and 95% and 91% at the protein level, respectively. The leucine zipper domain and two basic amino acid portions that bind DNA, as well as peptide sequences recognized by human cyto‐toxic T lymphocytes (CTLs), were all conserved in these rodent genes. Nuclear protein homologous to the 125 kD hSART‐1800 protein, but not to the 43 kD cytosol SART‐1259 protein, was detectable with specific antibody in the nuclear fractions of rodent tumor cell lines, and normal rodent fetal liver and testis. These rodent genes should be a novel tool for studies on the biological roles of the SART‐1 gene, and also in the construction of animal models of specific immuno‐therapy using SART‐1 gene products.

Cytokines Required for Induction of Histocompatibility Leukocyte Antigen‐class I‐restricted and Tumor‐specific Cytotoxic T Lymphocytes by a SART1‐derived Peptide

Although there have been several reports on peptides of human tumor‐rejection antigens capable of inducing histocompatibility leukocyte antigen (HLA)‐class I‐restricted and tumor‐specific cytotoxic T lymphocytes (CTLs), it is not yet clear which cytokines are required for CTL induction. This study has investigated the cytokine combinations required for optimal induction of CTLs by SARTI690–698 peptide, which is capable of inducing HLA‐A24‐restricted and tumor‐specific CTLs in peripheral blood mononuclear cells (PBMCs). Pretreatment of PBMCs as a source of antigen‐presenting cells (APCs) with interferon (IFN)‐γ, or to some extent with IFN‐α, but not with any of the other cytokines tested, augmented the peptide‐induced CTL activity in HLA‐A24 heterozygotes, but not in HLA‐A24 homozygotes. This IFN‐γ ‐mediated augmentation was inhibited by either interleukin (IL)‐4 or IL‐10. IL‐2 alone in culture, along with weekly stimulation by peptide‐pulsed APCs, was sufficient for the differentiation and proliferation of CTLs for the initial several weeks of culture. This IL‐2‐mediated activation of CTLs was inhibited by the addition of IFN‐γ, IL‐4, or IL‐10 to the IL‐2 culture. For further expansion of the CTLs, dendritic cells (DCs) induced from PBMCs with IL‐4 and granulocyte macrophage colony‐stimulating factor (GM‐CSF) were required as APCs. These results indicate that IFN‐γ and IL‐2 are important in the activation of APCs and CTLs, respectively, while GM‐CSF and IL‐4 are needed for the induction of DCs, which in turn are required for further expansion of mature CTLs. These results are important in allowing for a better understanding of the cellular and molecular basis of tumor‐specific immunity, and also for the development of peptide‐based specific immunotherapy.