Latest Articles
Metabolism
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Nature
Cytosolic acetyl-coenzyme A is a signalling metabolite to control mitophagy
Acetyl-coenzyme A (AcCoA) sits at the nexus of nutrient metabolism and shuttles between the canonical and non-canonical tricarboxylic acid cycle1,2, which is dynamically regulated by nutritional status, such as fasting3. Here we find that mitophagy is triggered after a reduction in cytosolic AcCoA levels through short-term fasting and through inhibition of ATP-citrate lyase (encoded byACLY), mitochondrial citrate/malate antiporter (encoded bySLC25A1) or acyl-CoA synthetase short chain family member 2 (encoded byACSS2), and the mitophagy can be counteracted by acetate supplementation. Notably, NOD-like receptor (NLR) family member X1 (NLRX1) mediates this effect. Disrupting NLRX1 abolishes cytosolic AcCoA reduction-induced mitophagy both in vitro and in vivo. Mechanically, the mitochondria outer-membrane-localized NLRX1 directly binds to cytosolic AcCoA within a conserved pocket on its leucine-rich repeat (LRR) domain. Moreover, AcCoA binds to the LRR domain and enhances its interaction with the nucleotide-binding and oligomerization (NACHT) domain, which helps to maintain NLRX1 in an autoinhibited state and prevents the association between NLRX1 and light chain 3 (LC3). Furthermore, we find that the AcCoA–NLRX1 axis underlies the KRAS-inhibitor-induced mitophagy response and promotes drug resistance, providing a metabolic mechanism of KRAS inhibitor resistance. Thus, cytosolic AcCoA is a signalling metabolite that connects metabolism to mitophagy through its receptor NLRX1.
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Nature
Lymph node environment drives FSP1 targetability in metastasizing melanoma
Ferroptosis has emerged as an actionable target to eliminate therapy-resistant and metastatic cancers1. However, which ferroptosis surveillance systems may offer a therapeutic window to leverage redox maladaptation in cancer remains unclear. In melanoma, glutathione peroxidase 4 (GPX4) impedes ferroptosis during haematogenous metastasis, but is dispensable during lymphatic metastasis2. Here, using a metastatic mouse melanoma model selected for lymph node metastasis, we show that lymph-node-derived metastatic cells exhibit markedly diminished expression of glutamate–cysteine ligase (GCLC) and reduced glutathione (GSH) levels relative to their parental counterparts. This metabolic shift occurs within the hypoxic lymphatic niche. Under comparable low-oxygen conditions, GPX4 undergoes ubiquitination and proteasomal degradation. In response, lymph node metastatic cells acquire increased reliance on ferroptosis suppressor protein 1 (FSP1), which is localized with perinuclear lysosomes. These findings reveal that the reduced reliance on the GPX4 axis enables melanoma cells to shift toward FSP1 dependency. Notably, intratumoural monotherapy with selective FSP1 inhibitors (viFSP1 and FSEN1) effectively suppresses melanoma growth in lymph nodes, but not in subcutaneous tumours, emphasizing a microenvironment-specific dependency on FSP1. Thus, targeting FSP1 in the lymph nodes holds strong potential for blocking melanoma progression.
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Nature
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Neuroblastoma is a highly lethal childhood tumour derived from differentiation-arrested neural crest cells1,2. Like all cancers, its growth is fuelled by metabolites obtained from either circulation or local biosynthesis3,4. Neuroblastomas depend on local polyamine biosynthesis, and the inhibitor difluoromethylornithine has shown clinical activity5. Here we show that such inhibition can be augmented by dietary restriction of upstream amino acid substrates, leading to disruption of oncogenic protein translation, tumour differentiation and profound survival gains in theTh-MYCNmouse model. Specifically, an arginine- and proline-free diet decreases the amount of the polyamine precursor ornithine and enhances tumour polyamine depletion by difluoromethylornithine. This polyamine depletion causes ribosome stalling, unexpectedly specifically at codons with adenosine in the third position. Such codons are selectively enriched in cell cycle genes and low in neuronal differentiation genes. Thus, impaired translation of these codons, induced by combined dietary and pharmacological intervention, favours a pro-differentiation proteome. These results suggest that the genes of specific cellular programmes have evolved hallmark codon usage preferences that enable coherent translational rewiring in response to metabolic stresses, and that this process can be targeted to activate differentiation of paediatric cancers.
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Nature
Molecular subtypes of human skeletal muscle in cancer cachexia
Cancer-associated muscle wasting is associated with poor clinical outcomes1, but its underlying biology is largely uncharted in humans2. Unbiased analysis of the RNAome (coding and non-coding RNAs) with unsupervised clustering using integrative non-negative matrix factorization3provides a means of identifying distinct molecular subtypes and was applied here to muscle of patients with colorectal or pancreatic cancer. Rectus abdominis biopsies from 84 patients were profiled using high-throughput next-generation sequencing. Integrative non-negative matrix factorization with stringent quality metrics for clustering identified two highly coherent molecular subtypes within muscle of patients with cancer. Patients with subtype 1 (versus subtype 2) showed clinical manifestations of cachexia: high-grade weight loss, low muscle mass, atrophy of type IIA and type IIX muscle fibres, and reduced survival. On the basis of differential expression between the subtypes, we identified biological processes that may contribute to cancer-associated loss of muscle mass and function, including altered posttranscriptional regulation and perturbation of neuronal systems; cytokine storm and cellular immune response; pathways related to extracellular matrix; and metabolic abnormalities spanning xenobiotic metabolism, haemostasis, signal transduction, embryonic and/or pluripotent stem cells, and amino acid metabolism. Differential expression between subtypes indicated the involvement of multiple intertwined higher-order gene regulatory networks, suggesting that network interactions of (hub) long non-coding RNAs, microRNAs and mRNAs could represent targets for future research.