title: Myc oncogene activation in B and T lymphoid tumours.
abstract: The chromosome translocations characteristic of certain B lymphoid tumours associate the myc oncogene and immunoglobulin loci. The typical t(12;15) in murine plasmacytomas and analogous t(14;8) in Burkitt lymphomas couple the myc coding region to one of the switch recombination regions within the immunoglobulin heavy (H) chain locus; hence the switch machinery may promote some translocations. Significantly, translocation induces constitutive myc expression, the untranslocated myc allele remaining silent. The predilection for breakpoints near the 5' end of the c-myc gene may reflect selection for altered myc regulation. In most tumours, the stimulatory effect of the H locus context is not understood, but an H locus enhancer participates in some tumours, including one displaying a novel transposition. The variant (6;15) translocations found in about 15% of plasmacytomas involve the myc band and the region of chromosome 6 where the kappa locus lies. The t(6;15) is shown here to represent an exchange between C kappa and a chromosome 15 locus (designated pvt-1) which lies unexpectedly far from c-myc. The association of myc expression with pvt-1 alterations suggest that myc can be activated at a distance. Myc has also been implicated in some T lymphomas by detection of proviral inserts near myc and also, surprisingly, within the pvt-1 locus. Inserts near myc appear to activate its expression via the retroviral enhancer.
authors.forename: J M
authors.initials: JM
authors.lastname: Adams
authors.forename: S
authors.initials: S
authors.lastname: Cory
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D002051:Burkitt Lymphoma / Q000235:genetics / Q000276:immunology; D002471:Cell Transformation, Neoplastic; D014644:Genetic Variation; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D008223:Lymphoma / Q000235:genetics* / Q000276:immunology; D051379:Mice; D009857:Oncogenes; D010954:Plasmacytoma / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D014178:Translocation, Genetic
chemical_list: D007143:Immunoglobulin Heavy Chains