Nuclear Acetyl-CoA as a SASP Rheostat: Tuning Senescent Cells Between Tumor Suppression and Chronic Inflammation

James Fischer (MD/PhD)· Mar 21, 2026

Mechanism: Nuclear acetyl-CoA levels, regulated by ACSS2, act as a rheostat shifting senescent cell SASP from pro-inflammatory to tumor-suppressive by differentially acetylating NF-κB versus FOXO3 promoters. Readout: Readout: High nuclear acetyl-CoA increases IL-6/IL-8 secretion and accelerates tumor growth, while ACSS2 inhibition reduces inflammation and suppresses tumor growth.

Hypothesis

Nuclear acetyl-CoA levels in senescent cells act as a rheostat that shifts the senescence-associated secretory phenotype (SASP) from a tumor‑suppressive, growth‑arresting state to a pro‑inflammatory, tissue‑damaging state by differentially acetylating histones at NF‑κB versus FOXO3 target promoters.

Mechanistic Rationale

Senocytes integrate metabolic cues into epigenetic decisions via acetyl-CoA–dependent histone acetylation. When nuclear acetyl-CoA is abundant, ACSS2–generated acetyl groups preferentially acetylate H3K27 at promoters of NF‑κB‑driven SASP components (IL-6, IL-8, CCL2), enhancing their transcription and creating a feed‑forward inflammatory loop. Conversely, limited nuclear acetyl-CoA reduces acetylation at these sites while permitting basal acetylation of FOXO3‑controlled promoters (e.g., IGFBP7, p21) that enforce cell-cycle arrest and secrete factors with tumor-suppressive and wound-healing properties. This bias explains the observed context-dependence of SASP: tissues with high acetate uptake or ACSS2 activity (e.g., inflamed macrophages) favor a detrimental SASP, whereas low-acetyl-CoA niches preserve a protective secretome.

Testable Predictions

Pharmacological elevation of nuclear acetyl-CoA (via acetate supplementation or ACSS2 over-expression) in senescent fibroblasts will increase NF-κB-p65 binding and H3K27ac at IL6 and IL8 promoters, while decreasing FOXO3 occupancy at IGFBP7.
CRISPR-mediated knock-down of ACSS2 in senescent cells will shift SASP composition toward higher IGFBP7 and lower IL-6, independent of p16^INK4a^ levels.
In vivo, intermittent acetate dosing in aged mice will elevate SASP inflammatory markers in liver and lung, whereas ACSS2 inhibition will reduce circulating IL-6 without affecting senescent cell burden measured by SA-β-gal.
Tumor models co-implanted with senescent stromal cells will show accelerated growth when stromal ACSS2 is high, but suppressed growth when ACSS2 is low, linking the rheostat to paracrine tumor suppression.

Experimental Design

In vitro: Induce senescence in human IMR-90 fibroblasts via irradiation. Treat groups with (a) sodium acetate (5 mM), (b) ACSS2 siRNA, (c) both, plus controls. Perform ChIP-seq for H3K27ac and p65, RNA-seq for SASP, and secretion assays (ELISA) for IL-6, IL-8, IGFBP7. Validate FOXO3 promoter acetylation by ChIP-qPCR.
Ex vivo: Isolate senescent cells from young and old mouse livers, manipulate ACSS2 with AAV-mediated over-expression or shRNA, then transplant into syngeneic hosts bearing sub-cutaneous MC38 tumors. Monitor tumor growth and serum cytokines.
In vivo: Feed aged (20-month) C57BL/6 mice either normal water or water supplemented with 2 % sodium acetate for 4 weeks, with a parallel cohort receiving the ACSS2 inhibitor compound-30. Assess hepatic and lung SASP via multiplex cytometry, quantify senescent cells by p16^INK4a^ immunostaining, and evaluate fibrosis histology.

Potential Implications

If validated, this hypothesis reframes senolytics not as blunt removal tools but as opportunities to metabolically re-program the SASP. Targeting nuclear acetyl-CoA flux could preserve the tumor-suppressive and wound-healing arms of senescence while dampening its chronic inflammatory burden, offering a precision strategy that avoids the tissue-repair deficits seen with continuous senolytic clearance.

Hypothesis

Mechanistic Rationale

Testable Predictions

Pharmacological elevation of nuclear acetyl-CoA (via acetate supplementation or ACSS2 over-expression) in senescent fibroblasts will increase NF-κB-p65 binding and H3K27ac at IL6 and IL8 promoters, while decreasing FOXO3 occupancy at IGFBP7.

CRISPR-mediated knock-down of ACSS2 in senescent cells will shift SASP composition toward higher IGFBP7 and lower IL-6, independent of p16^INK4a^ levels.

In vivo, intermittent acetate dosing in aged mice will elevate SASP inflammatory markers in liver and lung, whereas ACSS2 inhibition will reduce circulating IL-6 without affecting senescent cell burden measured by SA-β-gal.

Tumor models co-implanted with senescent stromal cells will show accelerated growth when stromal ACSS2 is high, but suppressed growth when ACSS2 is low, linking the rheostat to paracrine tumor suppression.

Experimental Design

In vitro: Induce senescence in human IMR-90 fibroblasts via irradiation. Treat groups with (a) sodium acetate (5 mM), (b) ACSS2 siRNA, (c) both, plus controls. Perform ChIP-seq for H3K27ac and p65, RNA-seq for SASP, and secretion assays (ELISA) for IL-6, IL-8, IGFBP7. Validate FOXO3 promoter acetylation by ChIP-qPCR.

Ex vivo: Isolate senescent cells from young and old mouse livers, manipulate ACSS2 with AAV-mediated over-expression or shRNA, then transplant into syngeneic hosts bearing sub-cutaneous MC38 tumors. Monitor tumor growth and serum cytokines.

In vivo: Feed aged (20-month) C57BL/6 mice either normal water or water supplemented with 2 % sodium acetate for 4 weeks, with a parallel cohort receiving the ACSS2 inhibitor compound-30. Assess hepatic and lung SASP via multiplex cytometry, quantify senescent cells by p16^INK4a^ immunostaining, and evaluate fibrosis histology.

Potential Implications