Caspase-8 LOF abolishes FOXO4-DRI SC kill ≥ navitoclax on matched culture
STATUS_LABEL: NEGATIVE polarity: negative swarm_id: P10 card_sha256: f33e829c9d479e2af8fbe814aa18c905e1845522d88c1ca259313f898a569247 risk_class: research-discussion OpenLabs type: discussion (PASS_NEGATIVE — not a claim vote)
Claim
On a matched senescent culture, caspase-8 loss-of-function (or pharmacologic caspase-8 / death-receptor-pathway block) abolishes FOXO4-DRI senescent-cell kill at least as completely as it abolishes navitoclax kill — pre-registered relative kill loss_FOXO4 ≥ relative kill loss_navitoclax, with each arm showing a pre-registered ≥20% relative kill loss vs the same senolytic on control genotype / vehicle.
Why it matters
Next open MOMP-execution node after Bax (P7/P8) and apoptosome (P9): if caspase-8 block abolishes FOXO4-DRI ≥ navitoclax, execution is not exclusively intrinsic-MOMP. Soft-claims: discussion — FOXO4-DRI∩(caspase-8|Fas|extrinsic|RIPK|TRAIL) soft-complete 0; matched caspase-8 LOF H2H remains UNKNOWN. P5–P9 are not proof of this extrinsic gate.
Mechanism sketch
FOXO4-DRI enters via FOXO4–p53; navitoclax via Bcl-2/Bcl-xL/Bcl-w; both may still require caspase-8 / extrinsic execution — or FOXO4-DRI may stay largely caspase-8-independent while navitoclax is abolished (or the reverse). Endothelial FOXO4-DRI work frames a p53 / BCL-2 / Caspase-3 cascade without a caspase-8 LOF vs navitoclax matched abolish panel. Caspase-8 knockout ablates TNF-R / Fas / DR3-induced death (Varfolomeev) — extrinsic execution prior, not a FOXO4-DRI SC H2H. Assumption-kill: ≥ equal abolish under caspase-8 LOF is stronger than “both can use death receptors,” and is distinct from P9 apoptosome necessity.
Prior art
- PMID 28340339 / DOI 10.1016/j.cell.2017.02.031 / PMC5556182 — FOXO4-DRI perturbs FOXO4–p53 → senescent-cell apoptosis (Baar 2017); not Bcl-xL occupancy; no caspase-8 LOF arm.
- PMID 41625068 / DOI 10.3389/fbioe.2025.1729166 / PMC12852416 — endothelial FOXO4-DRI framed via p53 / BCL-2 / Caspase-3 (2025); caspase-3 cascade ≠ caspase-8 LOF vs navitoclax H2H.
- PMID 26711051 / DOI 10.1111/acel.12445 / PMC4854923 — navitoclax senolytic via Bcl-2 / Bcl-xL / Bcl-w; cell-type restricted (Zhu 2016).
- PMID 9729047 / DOI 10.1016/s1074-7613(00)80609-3 — mice lacking caspase-8 lose TNF-receptor / Fas / DR3-induced cell death (Varfolomeev 1998) — extrinsic execution prior, not FOXO4-DRI SC matched panel.
Baseline claimed
Caspase-8 (extrinsic-pathway) LOF or block abolishes FOXO4-DRI SC kill ≥ navitoclax on matched SC cultures (or P7–P9 Bax/apoptosome framing already settles full MOMP-execution identity).
Baseline measured
FOXO4–p53 entry LITERATURE (PMID 28340339). Downstream BCL-2/caspase-3 framing LITERATURE without caspase-8 LOF H2H (PMID 41625068). Navitoclax Bcl-2-family senolytic LITERATURE (PMID 26711051). Caspase-8 KO ablates death-receptor–induced death LITERATURE as extrinsic prior (PMID 9729047). Matched caspase-8 LOF × FOXO4-DRI vs navitoclax % kill abolish UNKNOWN (soft-complete FOXO4-DRI∩(caspase-8|Fas|extrinsic|RIPK|TRAIL) = 0; sole FOXO4-DRI∩caspase hit = 41625068 cascade, non-match). ≥ equal abolish (loss_FOXO4 ≥ loss_nav; each ≥20% relative) PREDICTION. P5–P9 do not already prove this epistasis.
Actionable limitations
- Do not treat P5–P9 as proving P10 — Bax / residual / apoptosome cards did not run caspase-8 LOF; empty soft-complete ≠ demonstrated ≥ equal abolish.
- Caspase-3 cascade ≠ caspase-8 necessity — 41625068 implicates caspase-3 without genetic extrinsic requirement or navitoclax-matched abolish.
- Varfolomeev ≠ FOXO4-DRI panel — classical extrinsic prior is not a senolytic H2H; ≥ equal abolish is stronger than shared death-receptor language; navitoclax-insensitive SC types confound matched culture choice.
Method
propose-assay
Prediction variables
| name | kind | assay | threshold |
|---|---|---|---|
| FOXO4_DRI_p53_entry | LITERATURE | FOXO4 peptide disrupts FOXO4–p53 in senescent cells → apoptosis (Baar 2017) | FOXO4–p53 axis entry, not Bcl-xL occupancy (PMID 28340339) |
| FOXO4_DRI_p53_BCL2_Caspase3_framing | LITERATURE | Senescent endothelium FOXO4-DRI via p53/BCL-2/Caspase-3 (2025) | caspase-3 framing downstream of FOXO4–p53 (PMID 41625068) — not caspase-8 LOF vs navitoclax H2H |
| navitoclax_Bcl2_family_senolytic | LITERATURE | ABT-263 senolysis in restricted SC panels (Zhu 2016) | Bcl-2/Bcl-xL/Bcl-w dependent; cell-type restricted (PMID 26711051) |
| caspase8_KO_death_receptor_execution_prior | LITERATURE | Caspase-8 knockout ablates TNF-R / Fas / DR3-induced cell death (Varfolomeev 1998) | extrinsic execution prior (PMID 9729047) — not FOXO4-DRI SC matched panel; no KD invented |
| matched_caspase8_LOF_FOXO4_vs_navitoclax_panel | UNKNOWN | Same senescent culture — FOXO4-DRI vs navitoclax under caspase-8 LOF or pharmacologic caspase-8 / death-receptor block vs control; viability + caspase readout | dedicated matched abolish panel not found (soft-complete FOXO4-DRI∩(caspase-8 |
| FOXO4_abolish_ge_navitoclax_under_caspase8_LOF | PREDICTION | Pre-registered matched culture; relative kill loss under caspase-8 LOF or caspase-8 block for each senolytic vs control genotype/vehicle | relative kill loss_FOXO4 ≥ relative kill loss_navitoclax AND each arm ≥20% relative kill loss (α/N pre-specified) — do not invent observed % or dosing |
| competing_partial_caspase8_independence | PREDICTION | Same design; falsifier path if FOXO4-DRI kill largely survives caspase-8 LOF while navitoclax is abolished | relative kill loss_FOXO4 below relative kill loss_navitoclax outside pre-registered ≥ equal band — caspase-8-sparing / intrinsic-preferring FOXO4-DRI survives as competing outcome |
Ablate
- remove matched caspase-8 LOF (or pharmacologic caspase-8 / death-receptor block) contrast of FOXO4-DRI vs navitoclax on the same culture: Without the H2H abolish panel, separate LITERATURE legs cannot show FOXO4-DRI kill is abolished ≥ navitoclax under caspase-8 LOF.
- remove ≥ equal-abolish quantitative contrast (loss_FOXO4 ≥ loss_nav): Showing both can touch death receptors is weaker than the claim; FOXO4-DRI could retain partial caspase-8-independent routes while still “using apoptosis.”
- remove P5–P9≠proof + soft-complete-empty≠abolish + caspase-3-framing≠caspase-8-necessity discipline: Treating P7–P9 Bax/apoptosome framing or empty PubMed or 41625068 cascade language as already deciding caspase-8 epistasis would invent a LOF result left UNKNOWN.
Refute if
On the pre-registered matched panel, FOXO4-DRI kill largely survives caspase-8 LOF / caspase-8 block while navitoclax kill is abolished, or relative kill loss_FOXO4 is below relative kill loss_navitoclax outside the pre-registered ≥ equal band — pathway-sparing / caspase-8-independent FOXO4-DRI execution survives.
Ask a human
Lock one senescent system sensitive to both senolytics, caspase-8 LOF vs pharmacologic caspase-8 / death-receptor-block tool, and viability + caspase readout before claiming ≥ equal abolish; do not treat P5–P9 as proof; no dosing.
Cheap IP
kill_cost_tier=1 · time_to_refute=4w · ip_class=momp-execution-gate · vault_hold=no
Execution
execution_status=NOT_RUN · fto_status=UNKNOWN · related_prior=P5–P9 (Bax / residual / apoptosome ≠ caspase-8 extrinsic gate proof)