van Bokhoven, A. | bioRxiv Science

bioRxiv2024

Evolutionary conserved reciprocal senescence and tumor suppressor signals limit lifetime cancer

Cellular senescence features a durable exit from the cell cycle triggered by stress or carcinogens. The INK4 locus is inactivated in various cancers, yet in senescence, p16Ink4a is activated. Whether senescence is tumor-suppressing or -promoting remains a conundrum. We discovered an evolutionally-conserved Vertebrata INK4-homolog. This ink4ab triggers senescence upon oxidative- and/or carcinogenic-stress. Adult Ink4ab-deficient animals failed to activate senescence and developed spontaneous cancers. Combined Ink4ab and Tp53 deficiency revealed a reciprocal senescence and apoptosis regulation, controlling tumorigenesis, including retinoblastoma. INK4-hematopoietic-deficient mice exhibited p19Arf-dependent enhanced senescence-like phenotypes, uncontrolled cell proliferation, defective stem cell differentiation, and splenomegaly, with single-splenocytes spatially-enriched in senescence-associated secretory profiles. Our studies reveal the evolutionary origin of paradigms co-regulating senescence and tumor suppression and offer strategies to exploit these reciprocal pathways for cancer prevention and therapy.

cancer biology↗

bioRxiv2022

Polymorphic KIR3DL3 expression modulates tissue-resident and innate-like T cells.

Most human killer cell immunoglobulin-like receptors (KIR) are expressed by Natural Killer (NK) cells and recognize HLA class I molecules as ligands. Uniquely, KIR3DL3 is a conserved but polymorphic inhibitory KIR recognizing a B7 family ligand, HHLA2, and is implicated for immune checkpoint targeting. Because the expression profile and biological function of KIR3DL3 remained elusive, we searched extensively for KIR3DL3 transcripts, revealing expression is highly enriched in {gamma}{delta} and CD8+ T cells rather than NK cells. These KIR3DL3 expressing cells are rare in the blood and thymus, but more common in the lungs and digestive tract. High resolution flow cytometry and single cell transcriptomics showed that peripheral blood KIR3DL3+ T cells have an activated transitional memory phenotype and are hypofunctional. The TCR usage is biased towards genes from early rearranged TCR- variable segments or V{delta}1 chains. Whereas we detected no impact of KIR3DL3 polymorphism on ligand binding, variants in the proximal promoter and at residue 86 can reduce expression. Together, we demonstrate that KIR3DL3 is upregulated in response to unconventional T cell stimulation and that individuals may vary in their ability to express KIR3DL3. These results have implications for the personalized targeting of KIR3DL3/HHLA2 checkpoint inhibition.

immunology↗