The nuclear condensates of ESE3/EHF induce cellular senescence without the associated inflammatory secretory phenotype in pancreatic ductal adenocarcinoma

Abstract

Senescent cells are in a stable state of cell cycle arrest, leading to a natural barrier to tumorigenesis. Senescent cells secrete a pool of molecules, including cytokines, chemokines, proteases, and growth factors, termed the senescence-associated secretory phenotype (SASP), paradoxically contributing to pro-tumorigenic processes. However, the mechanism for regulating senescence and SASP in tumor cells remains unclear. Here, SPiDER senescence probe-based CRISPR/Cas9 library screening has identified ETS homologous factor (EHF) could effectively induce cellular senescence but without SASP, which could further significantly inhibit PDAC progression. Mechanically, tumoral EHF could form liquid-like condensates and further transcriptionally repress the expression of telomerase reverse transcriptase (TERT) and associated inflammatory factors, such as IL-6, CXCL12, etc. The reduction of TERT led to the telomere shortening and dysfunction of cancer cells, which further drove cellular senescence in PDAC. Moreover, EHF-mediated repression of inflammatory factors effectively declined the infiltration of immunosuppressive cells including MDSCs, Tregs, neutrophils, and promoted the accumulation of CD8⁺T cells and NK cells, which enhanced tumor immune surveillance. Furthermore, high throughput drug screening identified that Bilobetin could effectively promote the phase separation of EHF, which could further induce tumoral senescence but without SASP. In vivo, preclinical translational research uncovered that Bilobetin could ameliorate immunosuppressive tumor microenvironment (TME) and sensitize PDAC to anti-PD-1 therapy. Overall, our study revealed EHF as a potential candidate to overcome the paradoxical function of cellular senescence and elucidated the effects of its phase separation state on gene regulation, which provided new insights and strategies for PDAC treatment.