Bioactive ceramide induces cell death in part by promoting mitophagy. C18-ceramide levels are commonly reduced in head and neck squamous cell carcinoma, which correlates with poor prognosis, suggesting the potential of harnessing ceramide for cancer treatment. In this study, we evaluated the ability of the ceramide analog D-erythro-14-(1-pyridinium)-N-octadecanoyl-sphingosine selenite (LCL768) to induce mitophagy and metabolic stress in head and neck squamous cell carcinoma. Mechanistically, LCL768 induced ceramide synthase 1 (CerS1)–mediated endogenous C18-ceramide accumulation in mitochondria to mediate mitophagy, which did not require the CerS1 transporter p17/PERMIT but was dependent on DRP1 activation via nitrosylation at C644. DRP1 facilitated the anchoring of the endoplasmic reticulum (ER) and mitochondrial membranes by promoting the association between phosphatidylethanolamine in the ER and cardiolipin in mitochondrial membranes. Mutations of Drp1 that prevented its binding to ER and mitochondrial membranes blocked CerS1/C18-ceramide mitochondrial accumulation, inhibiting LCL768-mediated mitophagy. In addition, LCL768-driven mitophagy altered mitochondrial metabolism, resulting in fumarate depletion and leading to tumor suppression in vivo. Exogenous fumarate supplementation prevented LCL768-mediated mitophagy, mitochondrial trafficking of CerS1, ER–mitochondrial tethering, and tumor suppression in mice. Fumarate metabolism was associated with PARKIN succination at a catalytic cysteine (Cys431), inhibiting its association with PINK1 and ubiquitin, thereby preventing mitophagy. LCL768-induced fumarate depletion attenuated PARKIN succination to promote PARKIN activation and mitophagy, indicating a feedforward mechanism that regulates mitophagy and fumarate metabolism through PARKIN succination. These data provide a mechanism whereby LCL768/CerS1-C18-ceramide–mediated mitophagy and tumor suppression are regulated by Drp1 nitrosylation, fumarate depletion, and PARKIN succination, providing a metabolic stress signature for lethal mitophagy. Significance: The identification of a metabolic link between ceramide-induced mitophagy, fission, and fumarate depletion reveals an effective tumor suppressive strategy for head and neck squamous cell carcinoma.

Patients with Alzheimer's disease (AD) have a decreased incidence of cancer, with a cross-sectional analysis of a nationwide sample of adults finding 21-fold higher odds of cancer diagnosis in non-AD individuals compared with those with AD. In this study, we demonstrated that mitochondrial localization of AD-associated amyloid-β precursor protein (APP) and its cleavage product amyloid-β 40, but not mutant APP that lacks a mitochondrial localization signal, inhibits lipid stress–mediated hyperactive mitophagy in aging T cells, improving their antitumor functions. Growth of melanoma xenograft or carcinogen-induced oral cancer models was highly reduced in AD mice. Additionally, adoptive cell transfer–based immunotherapy using aging T cells isolated from AD mice suppressed tumor growth. The metabolic signature of stress-dependent mitophagy in T cells showed fumarate depletion, which was linked to decreased succination of Parkin and enhanced mitochondrial damage. Mechanistically, APP interaction with the TOMM complex at the outer mitochondrial membrane attenuated trafficking of ceramide synthase CerS6 to mitochondria in aging AD T cells, preventing ceramide-dependent mitophagy. Thus, APP restored mitochondrial fumarate metabolism and Parkin succination, improving antitumor functions of AD T cells in vitro and in vivo. Exogenous fumarate supplementation or healthy AD mitochondria transfer functionally mimicked the AD/APP phenotype in aging T cells, enhancing their antitumor activity to control tumor growth. Moreover, T cells isolated from aging donors showed elevated mitophagy with fumarate depletion, which was restored in T cells isolated from age-matched patients with AD. Together, these findings show that AD protects T cells against ceramide-dependent mitophagy and fumarate depletion to enhance antitumor functions. Significance: The reduced cancer risk in Alzheimer's disease patients is mediated by the amyloid-β 40 peptide, which inhibits aging-dependent mitophagy in T cells to improve antitumor immunity. See related commentary by Bieberich, p. 3579

Effects of exogenous fumarate on HNSCC tumor metabolism in response to LCL768.

Characteristics of AD cases and non-AD controls, 2016 to 2019 and 2021 Medical Expenditure Panel Survey (MEPS).

Demographic characteristics of human APP-high vs APP-low samples.

ATAD3 shuttles CerS6 to the mitochondria of aging T-cells and mitochondrial APP blocks this effect.