Activation of proto-oncogenes by disruption of chromosome neighborhoods [RNA-Seq]

Mutations such as gene fusion, translocation and focal amplification are a frequent cause of proto-oncogene activation during tumorigenesis, but such mutations do not explain all cases of proto-oncogene activation. Here we show that disruption of local chromosome conformation can also activate proto-oncogenes in human cells. We mapped chromosome structures in T-cell acute lymphoblastic leukemia (T-ALL), and found that active oncogenes and silent proto-oncogenes generally occur within insulated neighborhoods formed by the looping of two interacting CTCF sites co-occupied by cohesin. Recurrent microdeletions frequently overlap neighborhood boundary sites in T-ALL genomes, and we demonstrate that site-specific perturbation of loop boundaries is sufficient to activate the respective proto-oncogenes in non-malignant cells. We found somatic genomic rearrangements affecting loop boundaries in many cancers. These results suggest that chromosome structural organization is fundamental to identify functional somatic alterations in cancer genomes. Paired-end 80x80 Poly-A RNA-seq in Jurkat T-ALL