title: Tcrδ translocations that delete the Bcl11b haploinsufficient tumor suppressor gene promote atm-deficient T cell acute lymphoblastic leukemia.
abstract: ATM is the master regulator of the cellular response to DNA double strand breaks (DSBs). Deficiency of ATM predisposes humans and mice to αβ T lymphoid cancers with clonal translocations between the T cell receptor (TCR) α/δ locus and a 450 kb region of synteny on human chromosome 14 and mouse chromosome 12. While these translocations target and activate the TCL1 oncogene at 14q32 to cause T cell pro-lymphocytic leukemia (T-PLL), the TCRα/δ;14q32 translocations in ATM-deficient T cell acute lymphoblastic leukemia (T-ALL) have not been characterized and their role in cancer pathogenesis remains unknown. The corresponding lesion in Atm-deficient mouse T-ALLs is a chromosome t(12;14) translocation with Tcrδ genes fused to sequences on chromosome 12; although these translocations do not activate Tcl1, they delete the Bcl11b haploinsufficient tumor suppressor gene. To assess whether Tcrδ translocations that inactivate one copy of Bcl11b promote transformation of Atm-deficient cells, we analyzed Atm(-/-) mice with mono-allelic Bcl11b deletion initiating in thymocytes concomitant with Tcrδ recombination. Inactivation of one Bcl11b copy had no effect on the predisposition of Atm(-/-) mice to clonal T-ALLs. Yet, none of these T-ALLs had a clonal chromosome t(12;14) translocation that deleted Bcl11b indicating that Tcrδ translocations that inactivate a copy of Bcl11b promote transformation of Atm-deficient thymocytes. Our data demonstrate that antigen receptor locus translocations can cause cancer by deleting a tumor suppressor gene. We discuss the implications of these findings for the etiology and therapy of T-ALLs associated with ATM deficiency and TCRα/δ translocations targeting the 14q32 cytogenetic region.
authors.affiliation: a Division of Oncology; Department of Pediatrics; Children's Hospital of Philadelphia ; Philadelphia , PA USA.
authors.forename: Lori A
authors.initials: LA
authors.lastname: Ehrlich
authors.forename: Katherine
authors.initials: K
authors.lastname: Yang-Iott
authors.forename: Craig H
authors.initials: CH
authors.lastname: Bassing
mesh_terms: D000483:Alleles; D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D002875:Chromosomes; D005434:Flow Cytometry; D006801:Humans; D007621:Karyotyping; D008677:Metaphase; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010641:Phenotype; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D014178:Translocation, Genetic; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: C511143:Bcl11b protein, mouse; D011518:Proto-Oncogene Proteins; D016692:Receptors, Antigen, T-Cell, gamma-delta; D012097:Repressor Proteins; C490393:Tcl1 protein, mouse; D025521:Tumor Suppressor Proteins; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse
keywords: A-T, Ataxia Telangiectasia, Ea, TCRa transcriptional enhancer; ALL, acute lymphoblastic leukemia; ATM; ATM, Ataxia Telangiectasia mutated; BCL11B; DSB, DNA double strand break; SKY, spectral karyotyping; T-ALL; T-ALL, T cell acute lymphoblastic leukemia; TCR, T cell receptor; thymocytes; transformation; translocations