title: Forward and reverse changes in Ig/myc translocation carrying tumors.
abstract: Translocation of the c-myc protooncogene to an immunoglobulin locus is a rate-limiting step in the genesis of three B cell derived tumors: Burkitt lymphoma (BL) in humans, mouse plasmacytoma (MPC), and rat immunocytoma (RIC). The translocation appears as a rate-limiting step in the genesis of all three tumors. Its consequences have been best analyzed in BL. They involve a non-immunological and an immunological component. The former acts by preventing the B cell from leaving the cycling compartment and entering the resting stage when programmed to do so. The latter acts by the down-regulation of certain human leucocyte antigen (HLA) class I polymorphic specificities, adhesion molecules and Epstein-Barr virus (EBV) encoded proteins. Together, they contribute to the escape of the BL cell from the host immune response. We have also described a non-clonogenic, non-tumorigenic "revertant", subline among five EBV-convertants of an originally highly tumorigenic, EBV-negative BL line. The other four convertants have remained highly tumorigenic. Suppression of tumorigenicity is associated with a switch to a lymphoblastoid line (LCL)-like phenotype, accompanied by the appearance of several activation markers. It is suggested that the LCL-type immunoblast comes under the influence of host feedback that normally contribute to the constancy of the B cell pool.
authors.affiliation: Department of Tumor Biology, Karolinska Institute, Stockholm, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Klein
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000473:pathology*; D014408:Biomarkers, Tumor / Q000032:analysis; D002051:Burkitt Lymphoma / Q000235:genetics / Q000473:pathology*; D002454:Cell Differentiation; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D002883:Chromosomes, Human, Pair 14 / Q000648:ultrastructure; D002898:Chromosomes, Human, Pair 8 / Q000648:ultrastructure; D015972:Gene Expression Regulation, Neoplastic; D005803:Genes, Immunoglobulin; D016259:Genes, myc; D004854:Herpesvirus 4, Human / Q000502:physiology; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D051379:Mice; D010641:Phenotype; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics*; D014178:Translocation, Genetic; D014407:Tumor Cells, Cultured / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D007143:Immunoglobulin Heavy Chains; D016271:Proto-Oncogene Proteins c-myc