Although oncogene-induced senescence (OIS) is a potent tumor-suppressor mechanism, recent studies revealed that cells could escape from OIS with features of transformed cells. However, the mechanisms that promote OIS escape remain unclear, and evidence of post-senescent cells in human cancers is missing. Here, we unravel the regulatory mechanisms underlying OIS escape using dynamic multidimensional profiling. We demonstrate a critical role for AP1 and POU2F2 transcription factors in escape from OIS and identify senescence-associated chromatin scars (SACSs) as an epigenetic memory of OIS detectable during colorectal cancer progression. POU2F2 levels are already elevated in precancerous lesions and as cells escape from OIS, and its expression and binding activity to cis-regulatory elements are associated with decreased patient survival. Our results support a model in which POU2F2 exploits a precoded enhancer landscape necessary for senescence escape and reveal POU2F2 and SACS gene signatures as valuable biomarkers with diagnostic and prognostic potential.

The age-related decline in immunity is accompanied by the accumulation of senescent CD8⁺ T cells. Using senescent cell isolation coupled with multi-omics profiling, we reveal the transition to senescence to be controlled by chromatin state-specific transcription factor (TF) networks in younger and older donors independent of age. These TF networks mediate widespread enhancer remodeling, repressing cell identity genes while upregulating inflammatory and secretory pathways. Inhibition or downregulation of AP1, KLF5, or RUNX2 modulates the transcriptional output and partially restores the blunted response to stimulation of senescent CD8⁺ T cells. Senescent CD8⁺ T cell gene signatures also predict responsiveness to chimeric antigen receptor (CAR)-T cell therapy in diffuse large B cell lymphomas. Overall, our study defines the gene-regulatory mechanisms underlying human CD8⁺ T cell senescence, highlights TF network perturbation as a viable strategy to manipulate the senescence state, and identifies senescent CD8⁺ T cell gene signatures as prognostic tools for immunotherapy outcome.

Aberrant oncogenic signaling causes cells to transition into oncogene-induced senescence (OIS) to limit uncontrolled proliferation. Despite being a potent tumor suppressor mechanism, OIS is an unstable cell state susceptible to reprogramming that can promote tumorigenesis. Therefore, elucidating the underlying gene regulatory mechanisms that commit cells to OIS is critical to identifying actionable targets to modulate the senescence state. We previously showed that timely execution of the OIS program is governed by hierarchical transcription factor (TF) networks. However, the gene regulatory mechanisms that prime cells to commit to the OIS fate early upon oncogene hyperactivation are currently not known. Here, we leveraged our time-resolved multi-omic profiling approach to generate TF networks during the first 24 h of oncogenic HRAS^G12V activation. Using this approach, we demonstrate that the commitment to OIS requires the rearrangement of the TF network on a pre-established epigenomic landscape, priming the cells for the substantial chromatin remodeling that underpins the transition to OIS. Our results provide a detailed map of the chromatin landscape before cells transition to OIS thus offering a platform for manipulation of senescence outcomes of potentially therapeutic value.