Augmenting L3MBTL2-induced condensates suppresses tumor growth in osteosarcoma

STUB1-mediated ubiquitination of SLC25A10 regulates mitochondrial function and drives osteosarcoma progression: A novel therapeutic target

Osteosarcoma (OS) is a highly aggressive primary bone malignancy characterized by limited treatment options and poor clinical outcomes. Emerging evidence underscores the critical role of mitochondrial metabolism in tumor progression, positioning mitochondrial proteins as potential therapeutic targets. SLC25A10, a mitochondrial dicarboxylate carrier involved in redox homeostasis and fatty acid synthesis, has been implicated in various cancers; however, its role in OS remains unclear.In this study, we investigated the function of SLC25A10 in OS progression and its potential as a therapeutic target. Our results revealed that SLC25A10 expression is significantly upregulated in OS tissues and cell lines compared to normal bone tissue, and its elevated expression is associated with poor patient prognosis. Functional assays demonstrated that silencing SLC25A10 via shRNA or CRISPR/Cas9 significantly suppressed OS cell proliferation, migration, and mitochondrial function, resulting in mitochondrial membrane depolarization, oxidative damage, and apoptosis. In contrast, SLC25A10 overexpression promoted OS cell proliferation and migration. In vivo, knockout of SLC25A10 markedly inhibited the growth of subcutaneous OS xenografts in nude mice.Furthermore, we identified STUB1, an E3 ubiquitin ligase, as a negative regulator of SLC25A10. STUB1 knockdown reduced the ubiquitination of SLC25A10, leading to increased protein stability and elevated expression. Notably, lysine 254 (K254) was identified as a key site mediating STUB1-dependent ubiquitination of SLC25A10. STUB1-mediated downregulation of SLC25A10 suppressed OS cell proliferation and migration, indicating a tumor-suppressive role for STUB1 in OS through modulation of SLC25A10.Collectively, our findings demonstrate that SLC25A10 is essential for maintaining mitochondrial function and contributes to OS malignancy. Targeting SLC25A10 may represent a novel and promising therapeutic strategy for the treatment of osteosarcoma.

Multidimensional mechanisms of anxiety and depression in Parkinson's disease: Integrating neuroimaging, neurocircuits, and molecular pathways

Anxiety and depression are common non-motor symptoms of Parkinson's disease (PD) that significantly affect patients' quality of life. In recent years, our understanding of PD has advanced through multifaceted studies on the pathological mechanisms associated with anxiety and depression in PD. These classic psychiatric symptoms involve complex pathophysiology, with both distinct features and connections to the mechanisms underlying the aetiology of PD. Furthermore, the co-occurrence of anxiety and depression in PD blurs the boundaries between them. Therefore, a comprehensive summary of the pathogenic mechanisms associated with anxiety and depression will aid in better addressing the emergence of these classic psychiatric symptoms in PD. This article integrates neuroanatomical, neural projection, neurotransmitter, neuroinflammatory, brain-gut axis, neurotrophic, hypothalamic-pituitary-adrenal axis, and genetic perspectives to provide a comprehensive description of the core pathological alterations underlying anxiety and depression in PD, aiming to provide an up-to-date perspective and broader therapeutic prospects for PD patients suffering from anxiety or depression.

Aptamer-modified melittin micelles efficiently inhibit osteosarcoma deterioration by inducing immunogenic cell death

Osteosarcoma (OS) is the most common primary bone malignancy characterized by deposition of an immature osteoid matrix. OS treatment has proven challenging because of the high risk of metastatic progression and recurrence after chemotherapy. Melittin (MLT) is recognized as a potential antitumor candidate to overcome chemotherapy resistance and provoke superior immunostimulatory effects. However, the application of MLT to OS is hampered by severe toxic side effects and a lack of tumor-targeting ability. Herein, a self-assembled nanopolymer named LC09-MLT@F127 was developed by binding MLT with F127 micelles and then modifying an aptamer (LC09) for targeted drug delivery during OS treatment. LC09-MLT@F127 exhibited significant OS-targeting ability in vitro and in vivo owing to the aptamer LC09 decoration. Moreover, LC09-MLT@F127 significantly reduced the hemolytic toxicity of MLT while maintaining its tumor-killing ability. In an orthotopic transplantation model of OS, LC09-MLT@F127 induced immunogenic cell death and facilitated the maturation of dendritic cells (DCs), thereby resulting in the activation of tumor-specific immune responses and the inhibition of OS deterioration. Taken together, these finding suggest that LC09-MLT@F127 may be an encouraging MLT-based immunotherapy option for OS.

The Emerging Role and Mechanism of E2/E3 Hybrid Enzyme UBE2O in Human Diseases

The ubiquitin-proteasome system (UPS) plays a pivotal role in determining protein fate, regulating signal transduction, and maintaining cellular homeostasis. Protein ubiquitination, a key post-translational modification, is orchestrated by the sequential actions of three primary enzymes, ubiquitin-activating enzyme (E1), ubiquitin-conjugating enzyme (E2), and ubiquitin protein ligase (E3), alongside the regulatory influence of deubiquitinases (DUBs) and various cofactors. The process begins with E1, which activates ubiquitin molecules. Subsequently, E2 receives the activated ubiquitin from E1 and transfers it to E3. E3, in turn, recognizes specific target proteins and facilitates the covalent attachment of ubiquitin from E2 to lysine residues on the target protein. Among the E2 enzymes, ubiquitin-conjugating enzyme E2O (UBE2O) stands out as a unique E2-E3 hybrid enzyme. UBE2O directly mediates the ubiquitination of a wide array of substrates, including 5'-AMP-activated protein kinase catalytic subunit alpha-2 (AMPKα2), MAX interactor 1 (Mxi1), and v-maf musculoaponeurotic fibrosarcoma oncogene homolog (c-Maf), among others. In this narrative review, we will explore the structural characteristics of UBE2O and elucidate its molecular functions. Additionally, we will summarize recent advancements in understanding the role of UBE2O in various tumors, Alzheimer's disease (AD), and metabolic diseases. Finally, we will discuss the potential of targeting UBE2O as a novel therapeutic strategy for the treatment of human diseases.

Long non-coding RNA AC133552.2: biomarker and therapeutic target in osteosarcoma via PANoptosis gene screening

Osteosarcoma, the most common primary bone cancer in children and adolescents, presents significant challenges, particularly in metastasis and recurrence, resulting in poor survival rates. This study explores the role of PANoptosis-a complex cell death mechanism involving pyroptosis, apoptosis, and necroptosis-in osteosarcoma by identifying relevant long non-coding RNAs (lncRNAs) and their prognostic significance. Bioinformatics analyses used RNA expression data from the GEO and TARGET databases to identify differentially expressed genes (DEGs) and PANoptosis-related genes (PRGs). Co-expression analysis revealed lncRNAs linked to PRGs, forming a risk prognostic model. Five PRGs and two lncRNAs were significantly associated with prognosis, with the model showing high predictive accuracy (AUC 0.876, 0.787, and 0.794 for 1, 3, and 5 years). Notably, lncRNA AC133552.2 was downregulated in osteosarcoma tissues, correlating with poor survival and reduced immune infiltration. Silencing AC133552.2 promoted cell proliferation and migration, while overexpression inhibited tumor growth and metastasis, confirmed in xenograft models. AC133552.2 emerges as a potential biomarker and therapeutic target, with future research needed to explore its molecular mechanisms and clinical application.

Novel susceptibility genes for sleep apnea revealed by a cross-tissue transcriptome-wide association study

Sleep apnea (SA) is a sleep disorder characterized by frequent interruptions in breathing during sleep and is widely recognized as a significant global public health concern. Although genome-wide association studies (GWAS) have identified several loci associated with SA susceptibility, the underlying genes and biological mechanisms remain largely unknown. A cross-tissue transcriptome-wide association study (TWAS) was performed to integrate SA GWAS summary statistics from 410,385 individuals (43,901 cases and 366,484 controls) and gene expression data from 49 distinct tissues and obtained from 838 post-mortem donors. Functional Summary-based Imputation was employed to validate these findings in whole blood tissue. Additionally, candidate susceptibility genes were further verified using Gene Analysis combined with Multi-marker Analysis of Genomic Annotation. Subsequent Mendelian randomization and colocalization analyses were conducted. In the cross-tissue TWAS analysis, 60 susceptibility genes were identified. Two novel susceptibility genes, GPD2 and L3MBTL2, were validated through both single tissue TWAS and MAGMA analysis. Mitochondrial glycerophosphate dehydrogenase (GPD2) may reduce the SA risk by regulating energy metabolism, while Lethal (3) malignant brain tumor-like protein 2 (L3MBTL2) may increase the risk of SA by disturbing DNA damage repair pathway and by regulating the process of the cell cycle. In summary, two novel biological macromolecules were identified in our study whose expression was predicted to be associated with SA risk, providing new insight into the genetic basis of this condition.

Targeting RBM39 suppresses tumor growth and sensitizes osteosarcoma cells to cisplatin

Osteosarcoma is one of the most common malignant primary bone tumors and lacks effective therapeutic targets. Recent studies have reported that RNA binding proteins (RBPs) could serve as promising therapeutic targets for cancers, as their critical roles in transcriptional regulation and RNA splicing. Nevertheless, the potential of pharmacologically inhibiting RBPs as a therapeutic strategy for patients with osteosarcoma remains unclear. In this study, we identified the RNA-binding protein RBM39 as a promising therapeutic target for osteosarcoma. RBM39 is essential for cell viability, and a higher expression of RBM39 was associated with poor prognosis in osteosarcoma. Mechanistically, RBM39 served as a coactivator of c-Jun to transcriptionally upregulate DKK1, leading to the activation of the GSK3β-NF-κB pathway. Importantly, our results reveal that the pharmacological depletion of RBM39 by using the anti-cancer aryl sulfonamide (E7820), a drug known for its oral bioavailability and safe administration, effectively represses osteosarcoma growth and sensitizes osteosarcoma cells to cisplatin treatment both in vitro and in vivo. Our findings unveil the crucial role of RBM39 in modulating tumor growth and cisplatin sensitivity in osteosarcoma cells, suggesting that the combination of aryl sulfonamides with cisplatin may benefit patients with osteosarcoma.

Identification and functional characterization of T-cell exhaustion-associated lncRNA AL031775.1 in osteosarcoma: a novel therapeutic target

Background

Osteosarcoma, an aggressive bone malignancy predominantly affecting children and adolescents, presents significant therapeutic challenges with a 5-year survival rate below 30% in metastatic cases. T-cell exhaustion, characterized by the overexpression of immune checkpoint molecules, contributes to osteosarcoma progression and immune evasion. Although targeting these inhibitory pathways has shown potential in restoring T-cell activity, the molecular regulators of T-cell depletion in osteosarcoma are poorly understood.

Methods

This study employed comprehensive bioinformatics analyses on osteosarcoma samples from the TARGET database, combined with normal tissue data from the GTEx database, to identify T-cell exhaustion-associated genes and their co-expressed long non-coding RNAs (lncRNAs). Gene ontology and KEGG pathway analyses were used to elucidate immune-related pathway enrichments. A six-lncRNA prognostic model was established using LASSO regression and validated in separate cohorts. Functional assays evaluated the impact of the lncRNA AL031775.1 on osteosarcoma cell behavior and T-cell function.

Results

Twenty-four key T-cell exhaustion-related genes were identified and significantly enriched in immune-related pathways, indicating their importance in the osteosarcoma immune microenvironment. The constructed six-lncRNA model stratified patients by survival prognosis, showing robust predictive performance across cohorts. Among the six identified lncRNAs, AL031775.1 is notably downregulated in osteosarcoma patients and significantly promotes osteosarcoma cell proliferation, migration, and invasion while contributing to T-cell exhaustion. In T cells, downregulation of AL031775.1 impairs antitumor immunity, upregulates immune checkpoint molecules LAG3, PD1, and CTLA4, and diminishes T-cell cytotoxic activity against tumor cells.

Conclusion

This study identifies a novel six-lncRNA prognostic model and highlights the therapeutic potential of AL031775.1 in managing osteosarcoma by enhancing T-cell immunity and counteracting tumor progression. Targeting AL031775.1 represents a promising approach to improve immunotherapy efficacy in osteosarcoma. These findings provide critical insights into the molecular regulation of T-cell exhaustion and suggest a new avenue for therapeutic intervention.

The deubiquitinase USP44 enhances cisplatin chemosensitivity through stabilizing STUB1 to promote LRPPRC degradation in neuroblastoma

BACKGROUND

Dysregulated deubiquitinating enzymes (DUBs) execute as intrinsic oncogenes or tumor suppressors and are involved in chemoresistance in cancers. However, the functions and exact molecular mechanisms remain largely unclear in neuroblastoma.

METHODS

Here, an R2 screening strategy based on the standard deviation values was used to identify the most important DUB, USP44, in neuroblastoma with stage 4. We validated the role of USP44 regulation upon cisplatin treatment in vitro and in vivo experiments, revealing the molecular mechanisms associated with USP44 regulation and cisplatin sensitivity in neuroblastoma.

RESULTS

We found that low USP44 expression was associated with an inferior prognosis in neuroblastoma patients. Overexpression of USP44 enhanced neuroblastoma cell sensitivity to cisplatin in vitro and in vivo. Mechanistically, USP44 recruited and stabilized the E3 ubiquitin ligase STUB1 by removing its K48-linked polyubiquitin chains at Lys30, and STUB1 further reinforced the K48-linked polyubiquitination of LRPPRC at Lys453 and promoted its protein degradation, thus enhancing the accumulation of mitochondrial reactive oxygen species (mROS), in turn facilitating neuroblastoma cell apoptosis and cisplatin sensitivity. Additionally, overexpression of LRPPRC reversed the promoting effect of USP44 on cell apoptosis in cisplatin-treated neuroblastoma cells.

CONCLUSIONS

Our findings demonstrate that the USP44-STUB1-LRPPRC axis plays a pivotal role in neuroblastoma chemoresistance and provides potential targets for neuroblastoma therapy and prognostication.

"Intrinsic disorder-protein modification-LLPS-tumor" regulatory axis: From regulatory mechanisms to precision medicine

Liquid-Liquid Phase Separation (LLPS) is an important mechanism for the formation of functional droplets. Protein modification is an important pathway to regulate LLPS, in which series of modifying groups realize dynamic regulation by changing the charge and spatial resistance of the modified proteins. Meanwhile, uncontrolled protein modifications associated with LLPS dysregulation are highly correlated with tumorigenesis and development, suggesting the existence of a potential regulatory axis between the three. In this review, we pioneered "protein modification-LLPS-tumor" regulatory axis and summarized protein modifications that regulate LLPS in cancer cells (including phosphorylation, acetylation, methylation, ubiquitination, SUMOylation, lactate, ADP-ribosylation, O-glycosylation, and acylation) and their associated modification mechanisms. Finally, we outline advances in precision medicine based on this regulatory axis. The aim of this review is to expand the understanding of protein modifications regulating LLPS under normal or abnormal cellular conditions and to provide possible ideas for precision therapy.

Ubiquitination in osteosarcoma: unveiling the impact on cell biology and therapeutic strategies

Ubiquitination, a multifaceted post-translational modification, regulates protein function, degradation, and gene expression. The pivotal role of ubiquitination in the pathogenesis and progression of cancer, including colorectal, breast, and liver cancer, is well-established. Osteosarcoma, an aggressive bone tumor predominantly affecting adolescents, also exhibits dysregulation of the ubiquitination system, encompassing both ubiquitination and deubiquitination processes. This dysregulation is now recognized as a key driver of osteosarcoma development, progression, and chemoresistance. This review highlights recent progress in elucidating how ubiquitination modulates tumor behavior across signaling pathways. We then focus on the mechanisms by which ubiquitination influences osteosarcoma cell function. Finally, we discuss the potential for targeting the ubiquitin-proteasome system in osteosarcoma therapy. By unraveling the impact of ubiquitination on osteosarcoma cell physiology, we aim to facilitate the development of novel strategies for prognosis, staging, treatment, and overcoming chemoresistance.

PRKDC Induces Chemoresistance in Osteosarcoma by Recruiting GDE2 to Stabilize GNAS and Activate AKT

Chemoresistance is one of the major causes of poor prognosis in osteosarcoma. Alternative therapeutic strategies for osteosarcoma are limited, indicating that increasing sensitivity to currently used chemotherapies could be an effective approach to improve patient outcomes. Using a kinome-wide CRISPR screen, we identified PRKDC as a critical determinant of doxorubicin (DOX) sensitivity in osteosarcoma. The analysis of clinical samples demonstrated that PRKDC was hyperactivated in osteosarcoma, and functional experiments showed that the loss of PRKDC significantly increased sensitivity of osteosarcoma to DOX. Mechanistically, PRKDC recruited and bound GDE2 to enhance the stability of protein GNAS. The elevated GNAS protein levels subsequently activated AKT phosphorylation and conferred resistance to DOX. The PRKDC inhibitor AZD7648 and DOX synergized and strongly suppressed the growth of osteosarcoma in mouse xenograft models and human organoids. In conclusion, the PRKDC-GDE2-GNAS-AKT regulatory axis suppresses DOX sensitivity and comprises targetable candidates for improving the efficacy of chemotherapy in osteosarcoma. Significance: Targeting PRKDC suppresses AKT activation and increases sensitivity to doxorubicin in osteosarcoma, which provides a therapeutic strategy for overcoming chemoresistance.