Acyl-CoA-binding protein (ACBP, encoded by diazepam binding inhibitor, DBI) is an abundant intracellular regulator of lipid metabolism that also circulates systemically, yet the mechanisms governing its release and its relationship to organ injury remain unresolved. Herein, we combine human multi-omics, mechanistic mouse models and controlled cell death assays to identify cell death-driven liberation of intracellular ACBP/DBI as a unifying mechanism underlying its elevation in disease. In a cohort of 1198 hospitalized adults, among whom 75% were acutely infected by SARS-CoV-2, plasma ACBP/DBI tightly correlated with inflammatory markers and biochemical signatures of cardiac, hepatic, renal, metabolic and hematologic dysfunction. SomaScan proteomics further revealed that ACBP/DBI co-varies with organ-enriched proteins, particularly those originating from skeletal muscle and pancreas, implicating tissue injury as a major determinant of its circulating abundance. Multiple forms of acute organ damage in mice, including hepatic or renal ischemia-reperfusion, bile duct ligation, pancreatitis and rhabdomyolysis, triggered rapid and robust increases in plasma ACBP/DBI. Using defined in vitro paradigms, we demonstrate that apoptosis, ferroptosis and necroptosis each cause loss of intracellular ACBP/DBI and its release upon plasma membrane permeabilization, independent of the upstream lethal pathway. These mechanistic insights translated in vivo: hepatocyte apoptosis, ferroptosis and necroptosis each elevated circulating ACBP/DBI in a manner attenuated by pathway-specific inhibitors. Finally, meta-analysis of >100,000 individuals across diverse populations revealed that elevated plasma ACBP/DBI consistently associates with systemic and organ-specific disease and predicts future morbidity. Together, our findings identify cell death-driven ACBP/DBI release as a conserved mechanism linking organ injury to increased plasma ACBP/DBI, positioning this molecule as an integrative biomarker of tissue damage across species, organs, and cell death modalities.

Rational drug design seeks small molecules, aptamers, or peptides to disrupt key cellular targets. Autophagy, crucial in tumor formation, dormancy, and chemotherapy response, especially in breast cancer, requires potent, specific modulators. This study leverages rational peptide design to develop p62-LIR-derived peptides predicted to target the LC3B interaction interface and modulate autophagy-associated readouts, aiming to sensitize BC cells to chemotherapy. The 6-15-mer peptides, based on the LC3 interacting region (LIR) domain of p62, were evaluated in silico for predicted binding to the LC3B LIR-docking region. Two peptides, LIR-P1 (DDWTHLSRPMKWKK) and LIR-P2 (VHSADRDWTHLSKEV), were selected based on their HADDOCK scores and synthesized for studies in MCF-7 and TNBC MDA-MB 231 cells. At a non-toxic concentration (200μg/ml), both peptides effectively blocked autophagic flux in BC cells, as shown by western blot analysis of LC3B and p62 protein turnover. Fluorescence microscopy showed that LIR-P2 exhibited higher cellular uptake than LIR-P1, while functional assays were consistent with inhibition of autophagic flux. The combination of LIR-P2 and 5-FU synergistically increased chemotherapy cytotoxicity in MCF-7 and MDA-MB 231 cells, showing LIR-P2's potential to enhance treatment, especially in unresponsive TNBC. These findings support further investigation of p62-derived peptides as candidate modulators of autophagy and chemotherapy response in breast cancer cells.

Sequestosome 1 (p62/SQSTM1) is a multifunctional adaptor protein whose dysregulation promotes tumorigenesis through autophagy, metabolic reprogramming, and immune modulation. However, its role across cancer types and impact on the tumor immune microenvironment remain poorly defined. Here, we performed a comprehensive pan-cancer analysis to delineate the molecular and immunological landscape of p62 across human malignancies. TCGA analysis revealed rare mutations and limited prognostic impact of genomic alterations but marked transcriptomic upregulation in LIHC, LUAD, BRCA, KIRP, KICH, KIRC, and READ, correlating with poor survival, advanced stage, and higher T classification, particularly in BRCA and LUAD. Pathway analysis showed strong positive associations between p62 and metabolic adaptation and stress tolerance pathways, including oxidative phosphorylation, reactive oxygen species, and DNA repair, in most cancers. Notably, high p62 expression inversely correlated with immune cell infiltration in most epithelial cancers, such as BRCA, COAD, ESCA, HNSC, KIRC, LIHC, LUAD, LUSC, PAAD, PRAD, READ, THCA, while coinciding with elevated expression of immunosuppressive checkpoints such as PD-L1, B7-H3, EBAG9, PVR, and TGFB1, supporting a link between p62-driven metabolic remodeling and an immune-excluded tumor microenvironment. In contrast, GBM, LGG, OV, SARC, and TGCT showed positive correlations between p62 and immunoscore, with enrichment of interferon and pro-inflammatory pathways, reflecting a distinct immune-activated phenotype. Collectively, these findings identify p62 as a central regulator of tumor metabolism and immunity, suggesting that its context-dependent activity may dictate the balance between immune suppression and activation across cancers, and highlight two natural-product-derived PB1 inhibitors (ZINC70669789 and ZINC08877690) as promising candidates for therapeutic development.

Lysosomes contribute to the development of drug resistance through various mechanisms that include drug sequestration and the activation of adaptive stress pathways. While inhibitors of DNA-to-RNA transcription exhibit potent anticancer effects, the role of lysosomes in modulating responses to such transcription inhibitors remains largely unexplored. This study investigates this aspect in the context of two potent POLR1 (RNA polymerase I) transcription inhibitors, CX-3543 (quarfloxin) and CX-5461 (pidnarulex). Unexpectedly, CX-3543 was found to accumulate within lysosomes, leading to lysosomal membrane permeabilization (LMP) and the subsequent activation of cellular stress adaptation pathways, including those regulated by the transcription factor TFEB and autophagy. Disrupting TFEB or autophagy increased cell sensitivity to CX-3543, highlighting the cytoprotective role of these processes in counteracting CX-3543-induced cell death. Moreover, targeting lysosomal membranes with chloroquine derivatives or blue light exposure induced substantial LMP, releasing compound CX-3543 from lysosomes. This effect enhanced both the inhibition of DNA-to-RNA transcription and CX-3543-induced cell death. Similar effects were observed when chloroquine derivatives were combined with CX-5461. Additionally, combining CX-3543 with the chloroquine derivative DC661 more effectively reduced the fibrosarcoma growth in immunocompetent mice than either agent alone. Altogether, our results reveal an unanticipated lysosome-related mechanism that contributes to cancer cell resistance to POLR1 inhibitors and propose a strategy to overcome this resistance.Abbreviations: ATG7: autophagy related 7; ATG13: autophagy related 13; Baf A1: bafilomycin A1; CTSB: cathepsin B; DKO: double knockout; G4: Guanine quadruplex; KO: knockout; LAMP1: lysosomal associated membrane protein 1; LAMP2: lysosomal associated membrane protein 2; LGALS3: galectin 3; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MTORC1: mechanistic target of rapamycin kinase complex 1; NCL: nucleolin; POLR1: RNA polymerase I; SQSTM1/p62: sequestosome 1; TFEB: transcription factor EB; TFE3: transcription factor E3; ULK1: unc-51 like autophagy activating kinase 1.

Lysosomes are involved in the transport, degradation, and recycling of macromolecules through the autophagy and endocytosis pathways. Cholesterol is taken up by cells through the internalization of low-density lipoprotein (LDL) via LDL receptor-mediated endocytosis or micropinocytosis. Free cholesterol generated by the action of acid lipases contained in lysosomes can be transferred to other organelles. Dysfunctions in either cholesterol uptake or release from lysosomes can compromise the function and integrity of these organelles, thereby contributing to the pathogenesis of lysosomal storage disorders. We previously showed that some cationic amphiphilic drugs (CADs) mimic the phenotype of lysosomal storage disorders by inducing lysosomal cholesterol accumulation followed by lysosomal damage. Here, we describe two fluorescence microscopic methods for the visualization of cholesterol accumulation in lysosomes in response to the CAD leelamine. In the first method, the cell-permeable cholesterol analog labeled with the fluorophore BODIPY is used. In the second method, endogenous cholesterol-rich microdomains are labeled with filipin complex. Both methods imply the additional visualization of the lysosomal associated membrane protein 2 (LAMP2) by immunofluorescence. Finally, the role of lysosomal cholesterol accumulation in the induction of lysosomal membrane permeabilization (LMP) was assessed through a method based on the recruitment of Galectin-3 on damaged lysosomes.

Cancer treatment is often confounded by development of resistance to chemotherapy. This research explores the complex relationship between p62 (also known as SQSTM1), a multifunctional protein central in cancer signaling pathways - especially the NF-κB pathway - and chemoresistance. Our data indicate that disruption of the interaction between p62 and the serine/threonine protein kinase RIP1 is a viable strategy to counteract NF-κB activation and overcome chemoresistance. Employing a comprehensive drug repositioning approach, we utilized bioinformatics tools to perform docking, virtual screening, absorption, distribution, metabolism, and excretion analyses, toxicity analysis, and molecular dynamics simulations to identify FDA-approved drugs that prevent the binding of p62 to RIP1. Notable candidates, particularly montelukast and asunaprevir, blocked the p62-RIP1 interaction, establishing a basis for potential therapeutic interventions against chemoresistant cancers. This study highlights the critical role of the ZZ domain of p62 protein in chemotherapy resistance and sheds light on the possibility of repurposing existing drugs for novel applications in cancer treatment. Our findings provide a solid groundwork for preclinical studies.

Sertraline and indatraline are two antidepressants that function as serotonin reuptake inhibitors and have demonstrated promising anticancer potential, although their precise mechanisms of action remain unclear. Both compounds trigger cholesterol accumulation within lysosomes followed by lysosomal membrane permeabilization, ultimately leading to the activation of immunogenic cell death (ICD). This, in turn, triggers a T cell-mediated adaptive immune response that facilitates significant tumor control.

Lysosomotropism refers to the ability of certain basic lipophilic compounds to accumulate in lysosomes via pH partitioning. Various drugs including anticancer agents are trapped in lysosomes, and this process can prevent such drugs from reaching their primary target, thereby limiting their effectiveness. Strategies aimed at preventing drug sequestration or inducing drug release from lysosomes have garnered considerable interest. Chloroquine is a widely used anti-malarial drug that triggers lysosome membrane permeabilization (LMP) to liberate sequestered drugs from these organelles. In this study, we first evaluate the lysosomotropism of various fluorescent anticancer agents in silico. Next, we outline a simple, fast and robust method for the visualization and quantification of their lysosomal sequestration and release by fluorescence microscopy. The method is used on live cells and consists of two steps: (i) visualization of the compounds in lysosomes by analyzing their colocalization with a specific fluorescent lysosomal marker, and (ii) assessment of drug release from lysosomes. Furthermore, we present fluorescence microscopy protocols for monitoring LMP by analyzing the subcellular localization of LGALS3 (Galectin-3), which normally distributes diffusely in the cytoplasm but translocates into lysosomes upon LMP. This can be achieved on fixed cells by detecting endogenous LGALS3 with immunostaining or by the visualization of a transgenic LGALS3-mCherry fusion protein on live cells. Altogether, these methods facilitate qualitative and quantitative fluorescence imaging of lysosomal sequestration and liberation of lysosomotropic drugs.

In a recent paper published in Cell, Li et al. suggest that selective serotonin reuptake inhibitors (SSRIs) antidepressants act on serotonin transporters on CD8+ T cells to enhance antitumor immunity. Beyond this mechanism, SSRIs can act on malignant cells, as well as on other immune cells, to improve cancer immunosurveillance.

Cholesterol serves as a vital lipid that regulates numerous physiological processes. Nonetheless, its role in regulating cell death processes remains incompletely understood. In this study, we investigated the role of cholesterol trafficking in immunogenic cell death. Through cell-based drug screening, we identified two antidepressants, sertraline and indatraline, as potent inducers of the nuclear translocation of TFEB (transcription factor EB). Activation of TFEB was mediated through the autophagy-independent lipidation of MAP1LC3/LC3 (microtubule associated protein 1 light chain 3). Both compounds promoted cholesterol accumulation within lysosomes, resulting in lysosomal membrane permeabilization, disruption of autophagy and cell death that could be reversed by cholesterol depletion. Molecular docking analysis indicated that sertraline and indatraline have the potential to inhibit cholesterol binding to the lysosomal cholesterol transporters, NPC1 (NPC intracellular cholesterol transporter 1) and NPC2. This inhibitory effect might be further enhanced by the upregulation of NPC1 and NPC2 expression by TFEB. Both antidepressants also upregulated PLA2G15 (phospholipase A2 group XV), an enzyme that elevates lysosomal cholesterol. In cancer cells, sertraline and indatraline elicited immunogenic cell death, converting dying cells into prophylactic vaccines that were able to confer protection against tumor growth in mice. In a therapeutic setting, a single dose of each compound was sufficient to significantly reduce the outgrowth of established tumors in a T-cell-dependent manner. These results identify sertraline and indatraline as immunostimulatory agents for cancer treatment. More generally, this research shed light on novel therapeutic avenues harnessing lysosomal cholesterol transport to regulate immunogenic cell death.Abbreviation: ATG5: autophagy related 5; ATG13: autophagy related 13; DKO: double knockout; ICD: immunogenic cell death; KO: knockout; LAMP1: lysosomal associated membrane protein 1; LAMP2: lysosomal associated membrane protein 2; LGALS3: galectin 3; LDL: low-density lipoprotein; LMP: lysosomal membrane permeabilization; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTX: mitoxantrone; NPC1: NPC intracellular cholesterol transporter 1; NPC2: NPC intracellular cholesterol transporter 2; TFE3: transcription factor E3; TFEB: transcription factor EB; ULK1: unc-51 like autophagy activating kinase 1.

In a recent issue in Nature Cell Biology, Sung Min Son et al. unveil a novel layer in the regulation of the mTORC1/autophagy axis by EP300 which can undergo nucleocytoplasmic shuttling in response to alterations in nutrient availability. The study highlights that, in Hutchinson-Gilford progeria syndrome, overabundant cytoplasmic EP300 results in mTORC1 hyperactivation and impaired autophagy, potentially contributing to premature and accelerated aging.

Acute myeloid leukemia (AML) with FLT3-ITD mutation represents a quarter of AML patients and is associated with high relapse rate and dismal prognosis. FLT3 tyrosine kinase inhibitors (TKIs) were developed in order to target this genetic alteration and among these TKIs, AC220 (quizartinib) combined with chemotherapy has already shown an increased overall survival for patients with AML with FLT3-ITD mutation. Even though this increase in overall survival was significant, it remains discrete, and relapse rate is still high, so there is an unmet medical need. All-trans retinoic acid (ATRA) is well known for its effectiveness in acute promyelocytic leukemia (APL) treatment and has already been shown to have synergistic effects combined with another TKI, sorafenib. In this study, quizartinib, a more potent FLT3-TKI, was tested in combination with ATRA in the AML FLT3-ITD positive cell lines MOLM-13 and MV4-11. ATRA has effectively improved AC220 induced cell death via caspase activation. In addition, ATRA in combination with AC220 treatment notably enhanced BECN1 cleavage compared to AC220 treatment alone. Finally, in a xenotransplantation model ATRA plus AC220 was more efficient to reduce the leukemic burden than monotherapy with ATRA or AC220. Taken together, our results are a proof of the concept that ATRA and AC220 have synergistic anti-leukemic effects.

Acyl-CoA binding protein (ACBP) encoded by diazepam binding inhibitor (DBI) is an extracellular inhibitor of autophagy acting on the gamma-aminobutyric acid A receptor (GABAAR) γ2 subunit (GABAARγ2). Here, we show that lipoanabolic diets cause an upregulation of GABAARγ2 protein in liver hepatocytes but not in other major organs. ACBP/DBI inhibition by systemically injected antibodies has been demonstrated to mediate anorexigenic and organ-protective, autophagy-dependent effects. Here, we set out to develop a new strategy for developing ACBP/DBI antagonists. For this, we built a molecular model of the interaction of ACBP/DBI with peptides derived from GABAARγ2. We then validated the interaction between recombinant and native ACBP/DBI protein and a GABAARγ2-derived eicosapeptide (but not its F77I mutant) by pull down experiments or surface plasmon resonance. The GABAARγ2-derived eicosapeptide inhibited the metabolic activation of hepatocytes by recombinant ACBP/DBI protein in vitro. Moreover, the GABAARγ2-derived eicosapeptide (but not its F77I-mutated control) blocked appetite stimulation by recombinant ACBP/DBI in vivo, induced autophagy in the liver, and protected mice against the hepatotoxin concanavalin A. We conclude that peptidomimetics disrupting the interaction between ACBP/DBI and GABAARγ2 might be used as ACBP/DBI antagonists. This strategy might lead to the future development of clinically relevant small molecules of the ACBP/DBI system.

Supplementary Materials, Figures 1-5 from Disruption of Sphingosine 1-Phosphate Lyase Confers Resistance to Chemotherapy and Promotes Oncogenesis through Bcl-2/Bcl-xL Upregulation

Supplementary Figure Legends 1-2 from c-Jun NH2-Terminal Kinase Activation Is Essential for DRAM-Dependent Induction of Autophagy and Apoptosis in 2-Methoxyestradiol–Treated Ewing Sarcoma Cells

Lung cancer (LC) remains a leading cause of mortality worldwide, and new therapeutic strategies are urgently needed. One such approach revolves around the utilization of four-stranded nucleic acid secondary structures, known as G-quadruplexes (G4), which are formed by G-rich sequences. Ligands that bind selectively to G4 structures present a promising strategy for regulating crucial cellular processes involved in the progression of LC, rendering them potent agents for lung cancer treatment. In this review, we offer a summary of recent advancements in the development of G4 ligands capable of targeting specific genes associated with the development and progression of lung cancer.

Supplementary Figure 2 from c-Jun NH2-Terminal Kinase Activation Is Essential for DRAM-Dependent Induction of Autophagy and Apoptosis in 2-Methoxyestradiol–Treated Ewing Sarcoma Cells

Guanine-quadruplex structures (G4) are unusual nucleic acid conformations formed by guanine-rich DNA and RNA sequences and known to control gene expression mechanisms, from transcription to protein synthesis. So far, a number of molecules that recognize G4 have been developed for potential therapeutic applications in human pathologies, including cancer and infectious diseases. These molecules are called G4 ligands. When the biological effects of G4 ligands are studied, the analysis is often limited to nucleic acid targets. However, recent evidence indicates that G4 ligands may target other cellular components and compartments such as lysosomes and mitochondria. Here, we summarize our current knowledge of the regulation of lysosome by G4 ligands, underlying their potential functional impact on lysosome biology and autophagic flux, as well as on the transcriptional regulation of lysosomal genes. We outline the consequences of these effects on cell fate decisions and we systematically analyzed G4-prone sequences within the promoter of 435 lysosome-related genes. Finally, we propose some hypotheses about the mechanisms involved in the regulation of lysosomes by G4 ligands.

Autophagy is a catabolic lysosomal-dependent pathway involved in the degradation of cellular materials, supplying precursor compounds and energy for macromolecule synthesis and metabolic needs [...]

Acyl-coenzyme A (CoA)–binding protein (ACBP), also known as diazepam-binding inhibitor (DBI), is an extracellular feedback regulator of autophagy. Here, we report that injection of a monoclonal antibody neutralizing ACBP/DBI (α-DBI) protects the murine liver against ischemia/reperfusion damage, intoxication by acetaminophen and concanavalin A, and nonalcoholic steatohepatitis caused by methionine/choline-deficient diet as well as against liver fibrosis induced by bile duct ligation or carbon tetrachloride. α-DBI downregulated proinflammatory and profibrotic genes and upregulated antioxidant defenses and fatty acid oxidation in the liver. The hepatoprotective effects of α-DBI were mimicked by the induction of ACBP/DBI-specific autoantibodies, an inducible Acbp/Dbi knockout or a constitutive Gabrg2 F77I mutation that abolishes ACBP/DBI binding to the GABA A receptor. Liver-protective α-DBI effects were lost when autophagy was pharmacologically blocked or genetically inhibited by knockout of Atg4b . Of note, α-DBI also reduced myocardium infarction and lung fibrosis, supporting the contention that it mediates broad organ-protective effects against multiple insults.