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DENSPM (N1,N11-Diethylnorspermine)
Polyamine analogue / SSAT inducer
Evidence Score
38
Synthetic polyamine analogue that mimics endogenous spermine/spermidine to potently upregulate spermidine/spermine N1-acetyltransferase (SSAT/SAT1), the rate-limiting catabolic enzyme of the polyamine pathway. SSAT induction depletes intracellular spermidine and spermine pools, while concurrent activation of spermine oxidase (SMOX) generates H2O2 as a stoichiometric byproduct. In SDH-deficient cells, spermidine and spermine are specifically elevated in SDHx-mutated pheochromocytoma/paraganglioma tissues versus wild-type counterparts (Rai et al., Metabolism 2020, PMID: 32562798; confirmed in SDHB KD hPheo1 cells). DENSPM treatment caused significantly greater caspase-3-dependent apoptosis and lipid remodeling in SDHB-deficient cells than in wild-type cells (Alli et al., Physiol Rep 2026, PMID: 42249664). The selectivity mechanism is synergistic ROS toxicity: SDH-deficient cells already generate excess mitochondrial ROS from impaired Complex II electron flow; SMOX-derived H2O2 from DENSPM catabolism pushes them past the apoptotic threshold that wild-type cells tolerate. DENSPM suppressed growth of hPheo1 cells in vitro and in mouse xenografts (PMID: 32562798). Phase 1 safety data established in lymphoma/solid tumors; key limitation is lack of Phase 2 data in any neuroendocrine tumor.
Complex II dysfunction causes electron leak in the electron transport chain, increasing reactive oxygen species (ROS). This drives DNA damage but also creates a therapeutic vulnerability.
Upstream event:
Impaired electron flow through Complex II → electron leak
Downstream effects:
Spermidine and spermine are significantly elevated in SDHx-mutated pheochromocytoma/paraganglioma tissues and in SDHB-knockdown cells compared with wild-type controls, implying that SDH loss drives upregulation of the polyamine biosynthesis pathway. Polyamines support rapid cell proliferation and mitochondrial function; in SDH-deficient cells already under chronic oxidative stress, this pathway represents a synthetic vulnerability. Polyamine analogues such as DENSPM deplete natural polyamines by inducing SSAT-mediated catabolism and generate additional ROS via spermine oxidase, pushing these cells past their apoptotic threshold.
Upstream event:
SDH loss → altered mitochondrial metabolism → upregulation of polyamine biosynthesis (elevated spermidine, spermine in SDHx-mutated tumors)
Downstream effects:
SAT1
Spermidine/spermine N1-acetyltransferase 1
Rate-limiting enzyme of polyamine catabolism and the principal intracellular target induced by polyamine analogues including DENSPM. SAT1 acetylates spermidine and spermine, targeting them for export or oxidation by polyamine oxidase (PAOX), thereby depleting intracellular polyamine pools. Elevated SSAT/SAT1 activity in response to DENSPM treatment drives further ROS generation via SMOX, creating a toxic cycle in SDH-deficient cells already under oxidative stress.
UniProt: P21673
Evidence from PubMed, OpenTargets, and ChEMBL will appear here once external data integration is enabled.
Coming in Phase 3
For research exploration only — not medical advice. Consult your doctor before acting on any information.
Have Claude analyze this drug's repurposing potential for SDH-deficient diseases.