Identification of a glioma antigen, GARC‐1, using cytotoxic T lymphocytes induced by HSV cancer vaccine

Abstract

Despite several ongoing clinical trials of immunotherapies against glioma, few glioma-specific antigens recognized by cytotoxic T lymphocytes (CTLs) have been identified. We recently demonstrated that intratumoral inoculation with herpes simplex virus (HSV) as a cancer vaccine activates tumor-specific CTLs. To identify glioma antigens recognized by CTLs, we used the HSV cancer vaccine to vaccinate mice harboring a syngeneic mouse glioma cell line, GL261. From the splenocytes of the immunized mice, we generated an H-2D b -restricted CTL line, GCL-1, that was specific for GL261. Then, a cDNA expression library generated from GL261 was screened with GCL-1, and a new gene encoding glioma antigen, GARC-1, was isolated. Sequence analysis revealed that the GARC-1 gene isolated from GL261 had a point mutation causing an amino acid change (Asp to Asn at position 81). T-cell epitope analysis revealed that the mutated peptide GARC-1 77-85 (AALLN-KLYA) but not the wild-type peptide (AALLDKLYA), was recognized by GCL-1. These results suggest that HSV cancer vaccination may be a useful method for inducing tumor-specific CTLs and identifying tumor antigens. Furthermore, this GL261/ GARC-1 murine glioma model may be useful for the development of immunotherapy for brain tumors. ' 2005 Wiley-Liss, Inc.Key words: glioma; antigen; CTL; immunotherapy; HSV; G207; GL261; cancer vaccine Malignant brain tumors continue to be a major unsolved health problem throughout the world. Despite aggressive combined treatment modalities, little improvement has been made in the prognosis and survival of patients with malignant gliomas over the last decade. [1][2][3] The standard management of patients with malignant gliomas entails surgical resection followed by radiotherapy and chemotherapy. However, tumor progression inevitably occurs in almost all patients. 4 Therefore, the development of new therapeutic modalities for malignant gliomas is needed.Although the central nervous system (CNS) has long been considered an immunologically privileged site, recent studies have demonstrated that this privileged state is not absolute. [5][6][7][8] The presence of active immunity within the CNS supports the possibility of manipulating the immune system to create effective immunotherapy protocols against gliomas. 9,10 Recent progress in tumor immunology has highlighted the molecules involved in specific tumor immunity, including tumor rejection antigens recognized by CTLs. 11-15 Some of the antigenic peptides encoded by the tumor antigen genes have been used as a peptide-based vaccine in clinical trials for cancer patients, with tumor regression observed in some melanoma patients. 16,17 Despite several ongoing clinical trials of immunotherapies against glioma, however, few glioma antigens recognized by CTLs have been identified. To better understand the immune responses in the CNS and to design immunotherapeutic strategies against gliomas, glioma-specific antigens must be identified.A number of lytic viruses have been used in attempts to induce antitumor imm...

Combination of an agonistic anti-CD40 monoclonal antibody and the COX-2 inhibitor celecoxib induces anti-glioma effects by promotion of type-1 immunity in myeloid cells and T-cells

“…GL261 cells express T-cell epitopes derived from melanoma antigens gp100, tyrosinase-related protein 2 (TRP-2), EphA2 and GARC-1 [46–48]. However, in our data, the combination therapy did not induce detectable responses against these endogenously expressed antigen-epitopes in parental GL261 cells (Fig.…”

Downregulation of KIF23 suppresses glioma proliferation

“…Thus, SEREX is an effective method for the identification of useful tumor antigens. Several lytic viruses have been used in an attempt to induce antitumor immunoreactions by modifying tumor cells [28]. Most of these cancer vaccines have included oncolysates or membranes from tumor cells infected with the vaccinia virus [29], parainfluenza virus [30], Newcastle disease virus [31], etc.…”

Induction of protective and therapeutic antitumor immunity by a DNA vaccine with a glioma antigen, SOX6

“…Four hour 51 Cr release assays were performed as previously described. 11 In brief, target cells (GL261 and EL-4) were incubated with 50 lCi of Na 2 51 CrO 4 ( 51 Cr) for 60 min. Target cells (1 3 10 4 ) were then mixed with effector cells (Sp-SOX6 and Sp-vector) for 4 hr at the indicated effector-to-target ratios.…”