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PubMed2025

High p62 and ALDH1A3 Reduce the Effectiveness of Endocrine Therapy in Luminal B Breast Cancer.

BACKGROUND/AIM: High expression of p62 and ALDH1A3 indicates a poor clinical outcome in luminal B breast cancer, and p62 is involved in the progression of ALDH1-positive luminal B breast cancer stem cells. However, the association between endocrine therapy and high p62 and ALDH1A3 expression, in luminal B breast cancer remains unclear. MATERIALS AND METHODS: Two datasets with gene expression and clinical data for patients with primary breast cancer (METABRIC, n=2,509; The Cancer Genome Atlas, n=1,084) were downloaded and statistically analyzed. To evaluate the association between the p62 and ALDH1A3 expression levels and endocrine therapy, including tamoxifen and aromatase inhibitor, in patients with luminal B breast cancer, disease-specific survival was examined using Kaplan-Meier and multivariate Cox regression analyses. RESULTS: Patients with p62 high ALDH1A3 high luminal B breast cancer treated with endocrine therapy exhibited a poor prognosis. Moreover, patients with p62 high ALDH1A3 high luminal B breast cancer treated with tamoxifen showed a trend towards a poor prognosis, but those treated with aromatase inhibitors showed a significantly poor prognosis. These results suggest that endocrine therapy, especially aromatase inhibitors, exhibits a reduced effectiveness against p62 high ALDH1A3 high luminal B tumors. CONCLUSION: p62 and ALDH1A3 could be used together as a prognostic biomarker for predicting the efficacy of endocrine therapy for luminal B breast cancer.

ALDH1A3↗
PubMed2026

Activation of pro-survival autophagy by a small molecule promoting p62 oligomerization.

Autophagy is a critical mechanism of cellular quality control, orchestrated by selective autophagy receptor (SAR) proteins. Pharmacologically enhancing the cargo-targeting capacity of SARs presents an attractive but underexplored strategy for the precise therapeutic activation of autophagy. Here, we characterize SQ-1, a small-molecule activator of autophagy that engages the prototypical SAR protein p62/sequestosome-1 (SQSTM1). We show that SQ-1 sensitizes p62 to oxidation and promotes its disulfide-mediated oligomerization in response to mitochondrial reactive oxygen species (ROS). This ROS-dependent activation of p62-mediated selective autophagy enhances the clearance of ROS-generating mitochondria and restores cell viability in models of Niemann-Pick type C1 disease, which is marked by impaired autophagic flux. In summary, the unique mode of action of SQ-1 enables self-regulated autophagy activation, offering a potential therapeutic strategy for lysosomal storage disorders and a broader spectrum of age-related diseases characterized by defective autophagy.

Niemann-Pick type C1 disease↗
PubMed2026

p62/SQSTM1-KEAP1 complex prevents clearance of ubiquitinated Z alpha-1 antitrypsin and aggravates liver proteotoxicity.

Liver disease in Alpha-1 antitrypsin deficiency (AATD) is caused by the toxic accumulation of mutant Z alpha-1 antitrypsin (Z-AAT) within the endoplasmic reticulum (ER) of hepatocytes. Livers from PiZ transgenic mice expressing the human Z-AAT and AATD patients who are homozygotes for the allele expressing Z-AAT were found to have increased p62/SQSTM1, a multifunctional protein involved in protein homeostasis. The goal of this study was to elucidate the involvement of p62/SQSTM1 in the formation of Z-AAT globules that are responsible for liver injury in AATD. In the present study, we found that p62/SQSTM1 decorated ubiquitin-positive, Periodic-Acid Shiff-diastase-resistant Z-AAT globules and interacted with Z-AAT at the ER-cytosol interface. Genetic ablation of p62/SQSTM1 in PiZ mice (PiZ;p62-/-) led to marked reduction in hepatic Z-AAT globules and polymers, and decreased serum Z-AAT, highlighting a central role for p62/SQSTM1 in disease pathogenesis. Moreover, hepatocyte-specific somatic deletion of the ubiquitin-association (UBA) domain of p62/SQSTM1 reduced Z-AAT aggregation. Furthermore, KEAP1 was identified as a binding partner of p62/SQSTM1-Z-AAT complex, leading to nuclear translocation and activation of NRF2. Inhibition of KEAP1-p62/SQSTM1 interaction reduced the abundance of p62 and phosphorylated p62, decreased intracellular Z-AAT, and redistributed NRF2 to the cytoplasm. In conclusion, this study identifies p62/SQSTM1 as a regulator of Z-AAT proteostasis and link Z-AAT/p62 accumulation to KEAP1 sequestration and NRF2 pathway activation in liver disease due to Z-AAT.

AATD↗
PubMed2026

Enoxaparin induces apoptosis and autophagy, modulates inflammatory signaling, and reduces oxidative DNA damage in breast and liver cancer cells.

Cancer progression involves intricate interactions between inflammatory signaling, programmed cell death mechanisms, and oxidative stress. Although enoxaparin is widely used for managing cancer-associated thrombosis, its direct cellular effects on tumor biology remain insufficiently characterized. This study aimed to evaluate the impact of enoxaparin on apoptosis, autophagy, inflammatory mediators, and oxidative DNA damage in breast (MDA-MB-231) and liver (HepG2) cancer cell lines. MDA-MB-231, HepG2, and non-cancerous HEK-293 cells were treated with varying concentrations (5, 10, 20, 40, and 80 mg/mL) of enoxaparin for 24 and 48 h. Cell viability was assessed using the MTT assay, while apoptosis was quantified by TUNEL analysis. Immunofluorescence staining was employed to evaluate the expression of NF-κB, IL-6, TNF-α, LC3, and p62. Oxidative DNA damage was determined by measuring extracellular 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels using a competitive ELISA. Statistical analyses were conducted to compare the treated and control groups. Enoxaparin significantly reduced cell viability in MDA-MB-231 and HepG2 cells without inducing cytotoxicity in HEK-293 cells. Apoptosis was markedly increased in both cancer cell lines following treatment. Enoxaparin differentially modulated inflammatory signaling; NF-κB expression was significantly increased in MDA-MB-231 cells, accompanied by suppression of IL-6 and TNF-α, whereas no significant inflammatory changes were observed in HepG2 cells. Enoxaparin treatment was observed to increase LC3 and p62 expression in both MDA-MB-231 and HepG2 cells, triggering autophagy-related pathways. Moreover, enoxaparin significantly reduced extracellular 8-OHdG levels, suggesting a reduction in oxidative DNA damage. Enoxaparin exhibits multifaceted anticancer effects by promoting apoptosis and autophagy, selectively modulating inflammatory pathways, and reducing oxidative DNA damage in breast and liver cancer cells.

Humans↗
PubMed2025

Suppression of OTUD4 protects against myocardial ischemia-reperfusion injury by increasing autophagic flux and inhibiting apoptosis in cardiomyocytes.

Dysregulated autophagic flux plays a critical role in myocardial ischemia-reperfusion injury (MIRI), complicating cardiac reperfusion therapy. In this study, we identified OTUD4 as a potential regulator of autophagic flux in MIRI using CRISPR/Cas9 sgRNA sequencing. However, the underlying mechanism is poorly understood. The purpose of this study is to investigate the effects of OTUD4 on autophagic flux in OGD-R treated AC16 cells (IRI model in vitro) and LAD artery ligation induced myocardial ischemia-reperfusion mice (MIRI model in vivo). In the in vitro IRI cell model, OTUD4 knockdown significantly reversed impaired autophagic flux, increased mitochondrial membrane potential, and decreased LDH activity, ROS production, autophagy and apoptosis. Overexpression of OTUD4 showed the opposite result. In the in vivo MIRI model, OTUD4 knockdown also significantly decreased infarct area, improved cardiac structure and function, reduced serum BNP and LDH levels, attenuated cardiac tissue injury/fibrosis/myocardial hypertrophy, and ultimately exerted myocardial protective effects against ischemia-reperfusion injury. Importantly, OTUD4 knockdown inhibited autophagosome-associated markers (LC3II/LC3I, Beclin1, ATG9), autophagy substrate p62, increased lysosomal activity marker LAMP2, and activated the autophagy pathway (AKT/mTOR), thereby promoting the recovery of impaired autophagic flux in the MIRI model. Moreover, OTUD4 showed strong interaction with UBAC1, and OTUD4 deficiency decreases UBAC1 protein expression by impairing its deubiquitination, thereby regulating autophagy. In short, blocking OTUD4 restored damaged autophagic flux in I/R induced myocardial injury both in vivo and in vitro, inhibited myocardial cell apoptosis, and greatly improved cardiac function in ischemia-reperfusion mice. KEY MESSAGES: OTUD4 was identified as a key negative regulator of autophagy flux in myocardial ischemia-reperfusion injury (MIRI) via genome-wide CRISPR/Cas9 screening. OTUD4 knockdown exerts cardioprotective effects by reducing apoptosis and ROS generation and improving heart function in both in vitro and in vivo models. The interaction between OTUD4 and UBAC1 was confirmed, and OTUD4 maintains UBAC1 stability through deubiquitination, providing new insights into the ubiquitination regulatory mechanism in myocardial injury. Targeting OTUD4 has therapeutic potential for MIRI, as OTUD4 knockdown alleviated MIRI in both in vitro and in vivo models, suggesting the possibility of developing OTUD4 inhibitors for cardiac reperfusion treatment.

Animals↗
PubMed2026

Mitophagy-mediated ferroptosis involved in 2,5-hexanedione-induced neurotoxicity in rats.

n-Hexane, a widespread environmental and industrial pollutant, poses serious health risks, particularly neurotoxicity. Chronic exposure primarily induces sensorimotor neuropathy via its metabolite 2,5-hexanedione (HD), yet the mechanisms underlying HD-induced neuronal injury remain unclear. Recent evidence implicates ferroptosis, an iron-dependent form of regulated cell death, in neurodegenerative processes. In this study, Sprague-Dawley (SD) rats were exposed to HD to establish a neuropathy model. Ferroptosis involvement was assessed using the iron chelator deferoxamine (DFO) and the ferroptosis inhibitor Ferrostatin-1. The potential role of mitophagy in HD-induced ferroptosis was evaluated by monitoring mitophagy markers and by autophagy inhibition with chloroquine (CQ). In vitro, SH-SY5Y cells were transfected with PINK-1 siRNA to explore mitophagy-mediated regulation of ferroptosis. HD exposure led to iron accumulation, lipid peroxidation, mitochondrial abnormalities, and decreased GPX4 in rat spinal neurons. DFO or ferrostatin-1 treatment ameliorated these changes and preserved mitochondrial integrity. Mechanistic analyses revealed HD-induced activation of mitophagy, as shown by upregulation of Beclin-1, LC3II, Drp-1, and PINK-1, with concomitant downregulation of P62 in spinal mitochondria. CQ suppressed mitophagy, reduced iron deposition and lipid peroxidation, and improved motor function. Similarly, PINK-1 knockdown in SH-SY5Y cells mitigated HD-induced mitophagy and ferroptosis. These findings demonstrate that HD induces neuronal ferroptosis via mitophagy activation. Inhibition of ferroptosis or mitophagy effectively attenuates HD-induced neurotoxicity, suggesting potential therapeutic strategies to reduce neural damage from environmental n-hexane exposure.

Animals↗
PubMed2024

Proteomic Characterization of Ubiquitin Carboxyl-Terminal Hydrolase 19 Deficient Cells Reveals a Role for USP19 in the Secretion of Lysosomal Proteins.

Ubiquitin carboxyl-terminal hydrolase 19 (USP19) is a unique deubiquitinase, characterized by multiple variants generated by alternative splicing. Several variants bear a C-terminal transmembrane domain that anchors them to the endoplasmic reticulum. Other than regulating protein stability by preventing proteasome degradation, USP19 has been reported to rescue substrates from endoplasmic reticulum-associated protein degradation in a catalytic-independent manner, promote autophagy, and address proteins to lysosomal degradation via endosomal microautophagy. USP19 has recently emerged as the protein responsible for the unconventional secretion of misfolded proteins including Parkinson's disease-associated protein α-synuclein. Despite mounting evidence that USP19 plays crucial roles in several biological processes, the underlying mechanisms are unclear due to lack of information on the physiological substrates of USP19. Herein, we used high-resolution quantitative proteomics to analyze changes in the secretome and cell proteome induced by the loss of USP19 to identify proteins whose secretion or turnover is regulated by USP19. We found that ablation of USP19 induced significant proteomic alterations both in and out of the cell. Loss of USP19 impaired the release of several lysosomal proteins, including legumain (LGMN) and several cathepsins. In order to understand the underlaying mechanism, we dissected the USP19-regulated secretion of LGMN in several cell types. We found that LGMN was not a deubiquitinase substrate of USP19 and that its USP19-dependent release did not require their direct interaction. LGMN secretion occurred by a mechanism that involved the Golgi apparatus, autophagosome formation, and lysosome function. This mechanism resembled the recently described "lysosomal exocytosis," by which lysosomal hydrolases are secreted, when ubiquitination of p62 is increased in cells lacking deubiquitinases such as USP15 and USP17. In conclusion, our proteomic characterization of USP19 has identified a collection of proteins in the secretome and within the cell that are regulated by USP19, which link USP19 to the secretion of lysosomal proteins, including LGMN.

Humans↗
PubMed2026

Crotonylome profiling identifies MLKL crotonylation in lupus nephritis associated with RAB1A-mTOR signalling and autophagy changes in tubular epithelial cells.

OBJECTIVE: To investigate whether MLKL crotonylation is associated with tubular autophagy-lysosome pathway homeostasis in lupus nephritis (LN) and to explore its relationship with RAB1A-mechanistic target of rapamycin (mTOR) signalling. METHODS: Crotonylome proteomics was performed in peripheral blood mononuclear cells from patients with LN, patients with systemic lupus erythematosus without nephritis and healthy controls. Renal biopsy tissues were evaluated for tubulointerstitial fibrosis and autophagy-lysosome pathway-related markers. Mechanistic studies were conducted in lipopolysaccharide-stimulated HK-2 cells. Autophagic flux was assessed using bafilomycin A1. The dependency of mTOR/autophagy changes on RAB1A was tested by siRNA-mediated knockdown. RESULTS: MLKL was identified as a differentially crotonylated protein in LN, with increased crotonylation at K95 and K219. Kidney tissues from patients with LN showed increased fibronectin and collagen III deposition compared with controls, whereas no significant difference was observed between class IV and class V LN. LC3 signal did not differ significantly between groups, whereas LAMP1 expression and LC3-LAMP1 co-localisation were reduced in LN. In HK-2 cells, crotonylation-deficient MLKL mutants were associated with increased LC3-II and reduced p62, whereas K219Q showed the opposite pattern. Autophagic flux assays using bafilomycin A1 showed that K219R-expressing cells had higher LC3-II levels than WT cells both before and after lysosomal inhibition, with comparable BafA1-induced LC3-II accumulation, consistent with increased autophagosome formation rather than impaired lysosomal degradation. HDAC1 knockdown increased MLKL crotonylation and was accompanied by mTOR activation. MLKL crotonylation enhanced RAB1A guanriphosphat osphate (GTP) binding without altering total RAB1A abundance. RAB1A knockdown in MLKL WT-expressing cells attenuated mTOR phosphorylation and partly reversed the autophagy-suppressive marker profile. Sodium crotonate induced an autophagy-suppressive marker profile that was partly reversed by rapamycin. CONCLUSION: MLKL crotonylation is associated with activation of the RAB1A-mTOR axis and altered tubular autophagy-lysosome pathway homeostasis in LN. These findings suggest that tubular injury-related changes in LN may not be fully reflected by glomerulus-based classification alone.

Humans↗
PubMed2026

Oncolytic HSV-1-Mediated JAG1 Blockade Induces Glioma Senescence-Associated Secretory Phenotype to Increase Macrophage Activation and Cetuximab-Mediated Senolysis.

UNLABELLED: Oncolytic HSV-1 (oHSV) treatment induces Notch signaling and myelosuppression in the tumor microenvironment (TME) of preclinical cancer models. Clinically, the Notch ligand JAG1 was upregulated in patients with recurrent high-grade glioma treated with the oHSV CAN-3110 and correlated with poor prognosis. To better understand endogenous JAG1-mediated signaling in glioma cells and tumor-associated macrophages (TAM), we engineered a JAG1-antagonizing oHSV (OD-0J1) and interrogated its impact on cancer and myeloid cells in the TME. OD-0J1 antagonized JAG1-mediated Notch signaling and suppressed tumor growth in athymic nude and humanized mice, an effect reliant on Notch signaling in tumor cells. Kinome profiling revealed that OD-0J1 treatment suppressed CDK1, resulting in activation of the G2-M cell cycle checkpoint. Cell cycle arrest led to senescence and correlated with increased reactive oxygen species, p62, and autophagosome accumulation and senescence-associated β-galactosidase activity. OD-0J1-induced senescence resulted in increased production of inflammatory chemokines and damage-associated molecular patterns (DAMP), such as IL1β, HMGB1, and extracellular ATP. Coculturing macrophages with OD-0J1-infected tumor cells led to stimulation of chemotactic and proinflammatory pathways, as well as increased Fc receptor activation. Single-cell RNA sequencing and flow cytometric analysis of F4/80+ cells isolated from tumors showed a shift from tumor-supporting TAMs to inflammatory macrophages upon OD-0J1 treatment. Heightened EGFR activation in senescent cells was a mechanism to escape cell death, which created a unique opportunity for cetuximab as a senolytic agent. Combination therapy reduced EGFR signaling and induced macrophage-mediated antibody-dependent cellular cytotoxicity, thereby increasing the antitumor therapeutic efficacy of OD-0J1. SIGNIFICANCE: Leveraging JAG1 antagonism in the context of oncolytic virotherapy rewires macrophage polarization within the tumor microenvironment, which has wide implications for sensitizing tumors to antibodies, senolytic agents, and BiTE therapies.

Humans↗
PubMed2026

lncRNA JPX promotes radioresistance in nasopharyngeal carcinoma via the miR-1301-3p/PIK3R2-mediated autophagy pathway.

BACKGROUND: Nasopharyngeal carcinoma (NPC) represents an aggressive head and neck malignancy with high metastatic potential. Radioresistance remains a major therapeutic obstacle associated with poor prognosis. Although the long non-coding RNA (lncRNA) JPX has been implicated in various cancers, its specific role in NPC radioresistance requires further elucidation. This study aimed to investigate whether JPX modulates radiosensitivity through autophagy regulation and to delineate the underlying molecular mechanisms. METHODS: JPX expression was analyzed in NPC cell lines and The Cancer Genome Atlas (TCGA) datasets, with subcellular localization determined through cellular fractionation. Functional characterization was performed using short hairpin RNA (shRNA)-mediated knockdown in CNE-2 and HONE-1 cell lines. Radiosensitivity was evaluated by clonogenic survival assays at a clinically relevant radiation dose, with cell viability assessed by MTT as a screening measure. while autophagy activity was assessed through Western blot analysis of LC3-II and p62. Molecular interactions were validated using dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. RESULTS: JPX was significantly upregulated in head and neck squamous cell carcinoma (HNSCC) tissues and NPC cell lines, showing predominant cytoplasmic localization. Clinical association analysis in the TCGA-HNSCC cohort revealed that elevated JPX expression correlated with advanced tumor stage and poor overall survival, although NPC-specific clinical validation remains to be established. Genetic silencing of JPX attenuated autophagic flux and enhanced radiosensitivity. Mechanistic investigations revealed that JPX functions as a competitive endogenous RNA (ceRNA) functionally associating with miR-1301-3p, thereby alleviating miR-1301-3p-mediated repression of PIK3R2 and subsequently activating pro-survival autophagy pathways. CONCLUSIONS: The findings demonstrate that JPX promotes radioresistance in NPC through a ceRNA mechanism involving the miR-1301-3p/PIK3R2/autophagy regulatory axis. The JPX/miR-1301-3p/PIK3R2 axis thus emerges as a potential mechanistic candidate for radiosensitization; however, this notion remains strictly provisional and requires rigorous validation in authenticated NPC models, in vivo systems, and patient-derived samples before any translational consideration can be justified. Despite the cell line limitations acknowledged herein, our findings provide a mechanistic framework for understanding JPX-mediated radioresistance that warrants further investigation in more physiologically relevant models.

JPX↗