A recurrent chromosomal inversion suffices for driving escape from oncogene-induced senescence via subTAD reorganization

Oncogene-induced senescence (OIS) is an inherent and important tumor suppressor mechanism. However, if not removed timely via immune surveillance, senescent cells also have detrimental effects. Although this has mostly been attributed to the senescence-associated secretory phenotype (SASP) of these cells, we recently proposed that “escape” from the senescent state is another unfavorable outcome. The mechanism underlying this phenomenon remains elusive. Here, we exploit genomic and functional data from a prototypical human epithelial cell model carrying an inducible CDC6 oncogene to identify an early-acquired recurrent chromosomal inversion that harbors a locus encoding the circadian transcription factor BHLHE40. This inversion alone suffices for BHLHE40 activation upon CDC6 induction and driving cell cycle re-entry of senescent cells, and malignant transformation. Ectopic overexpression of BHLHE40 prevented induction of CDC6-triggered senescence. We provide strong evidence in support of replication stress-induced genomic instability being a causative factor underlying “escape” from oncogene-induced senescence. [Display omitted] •Oncogene-driven repair produces early genetic lesions, allowing escape from senescence•Cells escaping senescence display mutational signatures observed in individuals with cancer•A recurrent inversion harboring a circadian gene suffices for bypassing senescence•Chromatin loop and compartment remodeling support the “escape” transcriptional program Zampetidis et al. demonstrate that a recurrent chromosomal inversion harboring the circadian gene BHLHE40 is sufficient to drive escape from oncogene-induced senescence. The inversion is the outcome of oncogene-mediated genomic instability followed by chromatin refolding changes that activate the gene, leading to cell cycle re-entry and aggressive behavior.