| ObjectivesGlioblastoma multiforme ( GBM ) accounts for approximately one - third of all diagnosed brain tumors. Despite various treatment modalities, that include surgery, radiation and chemo - therapy, the prognosis for patients with GBM is very poor. New treatment methods are therefore warranted. Promising approaches include immunotherapy and gene therapy.The cloning and characterization of tumor associated antigens, and the i-dentification of the epitopes that can be recognized by cytotoxic T lymphocytes (CTLs) has opened new possibilities for cancer immunotherapy. In recent years, numerous attempts have been made to develop cancer immunotherapies, and encouraging results have been obtained both in vitro and in vivo. The characterization of glioma associated antigens such as tenacin, gp240 and EGFRvIII, make effective glioma immunotherapies feasible. The EGFRvIII mutation is present in 60 -70% of patients with glioblastoma multiforme ( GBM) and gliosarco-ma. This mutated receptor has not been detected in any normal tissue examined, which makes it a suitable target for glioma immunotherapy.With the development of simple protocols for maintenance and expansion of human DCs generated from bone marrow or PBMC, the use of DCs to present tumor antigen becomes a promising approach in cancer imunotherapy. In anti -tumor trials, DCs have been pulsed with peptides, tumor lysate or recombinant protein. Among these methods, peptide vaccination is the most widely investigated. Studies show that peptide pulsed DC immunization can generate tumor antigen specific cytolytic T cells against several kinds of human cancers. A major challenge for the development of peptide - based vaccines is the identification of the epitopes that may serve as targets for tumor - antigen specific CTLs.The majority of CTL epitopes of tumor - related antigens defined to date are associated with HLA a * 0201, which is the major subtype in most of the pre-dominant ethnic groups. Furthermore, HLA a * 0201 transgenic models have been successfully used to determine the immunogenicity of human CTL peptides derived from tumor associated antigens. HLA a * 0201 epitopes of GBM related antigens, therefore, may play an important role in GBM immunotherapy. Thus the identification of HLA a * 0201 GBM cell lines may be important for the evaluation of immunotherapies for glioblastoma in vitro or in animal models.Objective 1: In the present study, our first objective is to identify several HLA a * 0201 GBM cell lines by PCR - SSP followed by automatic sequencing. And further investigated whether these newly identified HLA a * 0201 glioma cell lines will be useful in the development of immunotherapies for treating GBM in experimental protocols that require specific HLA subtypes.In recent years, peptide epitopes for CTLs have been identified, but most of them are related to melanoma specific antigens such as tyrosinase, tyrosinase related protein 1 and 2, gp100, MAGE -1 and MAGE -3 et al. No EGFRvIII related MHC class I epitopes for CTLs have yet been characterized.Objective 2: In this experiment, the second objective is to identify EGFRvIII epitopes restricted by HLA a * 0201, and tested their capacity to elicit tumor specific CTLs.Over the last decade a significant number of tumor - tissue selective promoters and enhancer elements have been isolated that have potential for use in the gene therapy of malignancies. A gene, termed interleukin 13 receptor alpha 2 (IL - 13Ro2) , which has a possible glioma specific promoter , has been cloned from a human renal cell carcinoma cell line. Several lines of evidence indicate that IL - 13Ro2 is overexpressed in most human glioblstomas. In addition, the presence of IL - 13Ro2 in various regions of the brain and in other normal human organs is negligible. These characteristics of human IL - 13Ro2 make it an attractive target for treatments such as protein/peptide - based vaccines or immunotoxin therapy.Given the importance of IL - 13Ro2 as a target molecule for tumor treatment, the functional sig...
|
PDF Full Text Request