Parkin targets HIF-1α for ubiquitination and degradation to inhibit breast tumor progression

Risk of colorectal cancer in Parkinson's disease: a systematic review and meta-analysis of 11 million participants

BACKGROUND

In the last twenty years, epidemiological research has suggested a potential decreased susceptibility to cancer among individuals diagnosed with Parkinson's disease (PD), although conflicting findings exist regarding the connection between PD and Colorectal cancer (CRC). This systematic review and meta-analysis were conducted to investigate the contemporary epidemiological data on the risk of CRC in PD.

METHODS

A comprehensive search of the literature was conducted utilizing three databases: PubMed, Scopus, and Web of Science. We included observational studies (cross-sectional, case-control, and cohort) that examined the relationship between PD and CRC. We also analyzed data obtained from the Parkinson's Progression Markers Initiative (PPMI) to evaluate the frequency of CRC among individuals diagnosed with PD, control participants, and PD patients carrying the LRRK2 genetic variant.

RESULTS

We included 22 studies with a total of 1,3137,089 PD cases were included in our study. Our analysis demonstrated a significant relationship between PD and a reduced incidence of CRC (pooled RR = 0.80, 95% CI = 0.69-0.91). Subgroup analysis based on study design revealed a significant association in the cohort (pooled RR = 0.80, 95% CI = 0.66-0.93) and case-control studies (pooled RR = 0.77, 95% CI = 0.66-0.89). Also, sub-group analysis based on the study continent showed no significant association in North America (pooled RR = 0.83, 95% CI = 0.51-1.18, and Asia (pooled RR = 0.85, 95% CI = 0.55-1.15). However, analysis based on continents indicated significant results solely in Europe (pooled RR = 0.79, 95% CI = 0.71-0.86). PPMI analysis revealed distinct differences in CRC frequencies across the three groups (p < 0.001) with PD patients with LRRK2 genetic variant exhibited the highest frequency of colorectal cancer, followed closely by healthy subjects.

CONCLUSION

In conclusion, our study demonstrates a decreased risk of CRC in individuals with PD, suggesting an inverse association between the two diseases. Further research is warranted to elucidate the underlying mechanisms driving this correlation, paving the way for the development of targeted strategies for the prevention and management of both PD and CRC.

Targeting Autophagy for Pituitary Tumors

Pituitary tumors, arising from the pituitary gland, can be classified as functioning or non-functioning based on their hormone production. Previous studies demonstrated that impairment of cellular processes, such as autophagy, a crucial cellular recycling mechanism, has been implicated in pituitary tumorigenesis and hormone dysregulation. This review comprehensively examines the intricate relationship between autophagy and pituitary tumors. We explore the multifaceted role of autophagy in cancer, highlighting its dual nature as both a tumor suppressor and a promoter depending on the context. We also discuss the specific mechanisms of autophagy, including macroautophagy, mitophagy, crinophagy, and their relevance to pituitary tumorigenesis and hormone regulation. Furthermore, we analyze the current literature regarding the impact of various therapeutic interventions in pituitary tumor cells, with both autophagy-promoting and autophagy-inhibiting strategies. We address the challenges in interpreting autophagy activity and its complex interplay with hormone production. Current evidence suggests the potential of targeting autophagy as a therapeutic approach for pituitary tumors, emphasizing further research and clinical trials to determine the optimal strategy for individual patients and improve long-term outcomes.

Ncl liquid-liquid phase separation and SUMOylation mediate the stabilization of HIF-1α expression and promote pyroptosis in ischemic hindlimb

Liquid-liquid phase separation (LLPS) has emerged as a flexible intracellular compartment that modulates various pathological processes. Hypoxia-inducible factor-1α (HIF-1α) has been shown to play an essential role in inflammation after ischemic injury. However, the mechanisms underlying HIF-1α-induced inflammation in ischemic diseases have not been defined. This study found that HIF-1α mediated the progression of ischemia-induced muscle injury. After ischemic injury, SUMO1 is upregulated and rapidly activates NLRP3 inflammasome through the upregulation of HIF-1α, leading to enhanced inflammation and pyroptosis. Co-IP revealed an interaction between SUMO1 and HIF-1α and SUMOylation of HIF-1α at K477. Moreover, we demonstrated the important role of dynamic phase separation of Nucleolin (Ncl) in regulating HIF-1α mRNA stability through fluorescence recovery after photobleach (FRAP) analysis. The stability of HIF-1α is regulated by Ncl liquid-liquid phase separation and SUMOylation in ischemia-induced hindlimb injury. HIF-1α can promote the expression of NLRP3 and other inflammation-related molecules, leading to pyroptosis, suggesting that Ncl/LLPS/HIF-1α or SUMO1/HIF-1α pathway may be a new target for the treatment of inflammation in ischemic diseases. Although previous studies have found that HIF-1α is able to promote the expression of target genes after hypoxia, and these genes are used to maintain the stability of the intracellular environment to adapt to hypoxia. We found that HIF-1α is involved in the activation process of NLRP3 inflammasomes after hind limb ischemia, which enriches our understanding of the biological role of HIF-1α.

Roles of Post-Translational Modifications of Transcription Factors Involved in Breast Cancer Hypoxia

BC is the most commonly diagnosed cancer and the second leading cause of cancer death among women worldwide. Cellular stress is a condition that leads to disrupted homeostasis by extrinsic and intrinsic factors. Among other stressors, hypoxia is a driving force for breast cancer (BC) progression and a general hallmark of solid tumors. Thus, intratumoral hypoxia is an important determinant of invasion, metastasis, treatment failure, prognosis, and patient mortality. Acquisition of the epithelial-mesenchymal transition (EMT) phenotype is also a consequence of tumor hypoxia. The cellular response to hypoxia is mainly regulated by the hypoxia signaling pathway, governed by hypoxia-inducible factors (HIFs), mainly HIF1α. HIFs are a family of transcription factors (TFs), which induce the expression of target genes involved in cell survival and proliferation, metabolic reprogramming, angiogenesis, resisting apoptosis, invasion, and metastasis. HIF1α cooperates with a large number of other TFs. In this review, we focused on the crosstalk and cooperation between HIF1α and other TFs involved in the cellular response to hypoxia in BC. We identified a cluster of TFs, proposed as the HIF1α-TF interactome, that orchestrates the transcription of target genes involved in hypoxia, due to their post-translational modifications (PTMs), including phosphorylation/dephosphorylation, ubiquitination/deubiquitination, SUMOylation, hydroxylation, acetylation, S-nitrosylation, and palmitoylation. PTMs of these HIF1α-related TFs drive their stability and activity, degradation and turnover, and the bidirectional translocation between the cytoplasm or plasma membrane and nucleus of BC cells, as well as the transcription/activation of proteins encoded by oncogenes or inactivation of tumor suppressor target genes. Consequently, PTMs of TFs in the HIF1α interactome are crucial regulatory mechanisms that drive the cellular response to oxygen deprivation in BC cells.

HIF-1 and HIF-2 in cancer: structure, regulation, and therapeutic prospects

Hypoxia, or a state of low tissue oxygenation, has been characterized as an important feature of solid tumors that is related to aggressive phenotypes. The cellular response to hypoxia is controlled by Hypoxia-inducible factors (HIFs), a family of transcription factors. HIFs promote the transcription of gene products that play a role in tumor progression including proliferation, angiogenesis, metastasis, and drug resistance. HIF-1 and HIF-2 are well known and widely described. Although these proteins share a high degree of homology, HIF-1 and HIF-2 have non-redundant roles in cancer. In this review, we summarize the similarities and differences between HIF-1α and HIF-2α in their structure, expression, and DNA binding. We also discuss the canonical and non-canonical regulation of HIF-1α and HIF-2α under hypoxic and normal conditions. Finally, we outline recent strategies aimed at targeting HIF-1α and/or HIF-2α.

The interconnective role of the UPS and autophagy in the quality control of cancer mitochondria

Uncontrollable cancer cell growth is characterized by the maintenance of cellular homeostasis through the continuous accumulation of misfolded proteins and damaged organelles. This review delineates the roles of two complementary and synergistic degradation systems, the ubiquitin-proteasome system (UPS) and the autophagy-lysosome system, in the degradation of misfolded proteins and damaged organelles for intracellular recycling. We emphasize the interconnected decision-making processes of degradation systems in maintaining cellular homeostasis, such as the biophysical state of substrates, receptor oligomerization potentials (e.g., p62), and compartmentalization capacities (e.g., membrane structures). Mitochondria, the cellular hubs for respiration and metabolism, are implicated in tumorigenesis. In the subsequent sections, we thoroughly examine the mechanisms of mitochondrial quality control (MQC) in preserving mitochondrial homeostasis in human cells. Notably, we explored the relationships between mitochondrial dynamics (fusion and fission) and various MQC processes-including the UPS, mitochondrial proteases, and mitophagy-in the context of mitochondrial repair and degradation pathways. Finally, we assessed the potential of targeting MQC (including UPS, mitochondrial molecular chaperones, mitochondrial proteases, mitochondrial dynamics, mitophagy and mitochondrial biogenesis) as cancer therapeutic strategies. Understanding the mechanisms underlying mitochondrial homeostasis may offer novel insights for future cancer therapies.

ITGB4/GNB5 axis promotes M2 macrophage reprogramming in NSCLC metastasis

OBJECTIVE

Metastasis of non-small cell lung cancer (NSCLC) is a leading cause of high mortality. In recent years, the role of M2 macrophages in promoting tumor metastasis within the tumor microenvironment has garnered increasing attention. This study aims to investigate the role and potential mechanisms of the ITGB4/GNB5 axis in regulating M2 macrophage reprogramming and influencing NSCLC metastasis.

METHODS

This study first used single-cell sequencing technology to reveal the diverse subpopulation structure of NSCLC tumor tissues. Data analysis then identified the correlation between M2 macrophages and the malignant phenotype of NSCLC. Flow cytometry and immunohistochemistry were used to detect changes in M2 macrophages in NSCLC tissues. The impact of the ITGB4/GNB5 axis on M2 macrophage function was assessed through RNA sequencing and proteomic analysis. Finally, in vitro cell experiments and in vivo mouse models were used to validate the function and regulatory mechanisms of this axis.

RESULTS

Our study found diverse cellular subpopulations in NSCLC tumor tissues, with M2 macrophages closely associated with the malignant phenotype of NSCLC. We identified ITGB4 as a characteristic gene of NSCLC and predicted GNB5 as an interacting gene through database analysis. Activation of the ITGB4/GNB5 axis was shown to enhance M2 macrophage polarization, promoting their accumulation in the tumor microenvironment. This change further facilitated NSCLC invasion and metastasis by modulating related cytokines and signaling pathways. Animal experiments demonstrated that inhibition of the ITGB4/GNB5 axis significantly reduced tumor growth and metastasis.

CONCLUSION

The ITGB4/GNB5 axis reshapes the TME by promoting M2 macrophage polarization and functional enhancement, thereby facilitating tumor invasion and metastasis in NSCLC. This research provides new insights into the molecular mechanisms of NSCLC and offers potential molecular targets for future targeted therapies.

Ubiquitination Enzymes in Cancer, Cancer Immune Evasion, and Potential Therapeutic Opportunities

Ubiquitination is cells' second most abundant posttranslational protein modification after phosphorylation. The ubiquitin-proteasome system (UPS) is critical in maintaining essential life processes such as cell cycle control, DNA damage repair, and apoptosis. Mutations in ubiquitination pathway genes are strongly linked to the development and spread of multiple cancers since several of the UPS family members possess oncogenic or tumor suppressor activities. This comprehensive review delves into understanding the ubiquitin code, shedding light on its role in cancer cell biology and immune evasion. Furthermore, we highlighted recent advances in the field for targeting the UPS pathway members for effective therapeutic intervention against human cancers. We also discussed the recent update on small-molecule inhibitors and PROTACs and their progress in preclinical and clinical trials.

Proteasomal Dysfunction in Cancer: Mechanistic Pathways and Targeted Therapies

Proteasomes are the catalytic complexes in eukaryotic cells that decide the fate of proteins involved in various cellular processes in an energy-dependent manner. The proteasomal system performs its function by selectively destroying the proteins labelled with the small protein ubiquitin. Dysfunctional proteasomal activity is allegedly involved in various clinical disorders such as cancer, neurodegenerative disorders, ageing, and so forth, making it an important therapeutic target. Notably, compared to healthy cells, cancer cells have a higher protein homeostasis requirement and a faster protein turnover rate. The ubiquitin-proteasome system (UPS) helps cancer cells increase rapidly and experience less apoptotic cell death. Therefore, understanding UPS is essential to design and discover some effective inhibitors for cancer therapy. Hereby, we have focused on the role of the 26S proteasome complex, mainly the UPS, in carcinogenesis and seeking potential therapeutic targets in treating numerous cancers.

Targeting mammalian N-end rule pathway for cancer therapy

Regulated protein degradation plays a crucial role in maintaining proteostasis along with protein refolding and compartmentalisation which collectively control biological functions. The N-end rule pathway is a major ubiquitin-dependent protein degradation system. The short-lived protein substrates containing destabilizing amino acid residues (N-degrons) are recognized by E3 ubiquitin ligases containing UBR box domains (N-recognin) for degradation. The dysregulated pathway fails to maintain the metabolic stability of the substrate proteins which leads to diseases. The mammalian substrates of this pathway are involved in many hallmarks of cancer such as resisting cell death, evading growth suppression, chromosomal instability, angiogenesis, and deregulation of cellular metabolism. Besides, mutations in E3 N-recognin have been detected in human cancers. In this review, we discuss the mammalian N-end rule pathway components, functions, and mechanism of degradation of substrates, and their implications in cancer pathogenesis. We also discuss the impact of pharmacological and genetic inhibition of this pathway component on cancer cells and chemoresistance. We further highlight how this pathway can be manipulated for selective protein degradation; for instance, using PROTAC technique. The challenges and future perspectives to utilize this pathway as a drug target for cancer therapy are also discussed.

The role of mitochondria in tumor metastasis and advances in mitochondria-targeted cancer therapy

Mitochondria are central actors in diverse physiological phenomena ranging from energy metabolism to stress signaling and immune modulation. Accumulating scientific evidence points to the critical involvement of specific mitochondrial-associated events, including mitochondrial quality control, intercellular mitochondrial transfer, and mitochondrial genetics, in potentiating the metastatic cascade of neoplastic cells. Furthermore, numerous recent studies have consistently emphasized the highly significant role mitochondria play in coordinating the regulation of tumor-infiltrating immune cells and immunotherapeutic interventions. This review provides a comprehensive and rigorous scholarly investigation of this subject matter, exploring the intricate mechanisms by which mitochondria contribute to tumor metastasis and examining the progress of mitochondria-targeted cancer therapies.

Hypoxia-induced mitochondrial fission regulates the fate of bone marrow mesenchymal stem cells by maintaining HIF1α stabilization

For mesenchymal stem cells derived from bone marrow, a controlled reduction in ambient oxygen concentration has been recognized as a facilitator of osteogenic differentiation and the formation of calcium nodules. However, the specific molecular mechanisms underlying this phenotype remain unclear. The aim of this study was to elucidate the impact of hypoxia on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and to explore the involvement of mitophagy and the regulation of mitochondrial dynamics mediated by the mitochondrial dynamic regulatory factor FUN14 domain-containing 1 (FUNDC1). Our findings suggest that FUNDC1 is required for promoting osteogenic differentiation in BMSCs under hypoxic conditions. However, this effect was not dependent on FUNDC1-mediated mitophagy but rather on FUNDC1-mediated regulation of mitochondrial fission. At the mechanistic level, FUNDC1 binds more DNM1L and less OPA1 under hypoxic conditions, leading to an upsurge in mitochondrial division. This heightened mitochondrial division culminates in the increased translocation of Parkin to mitochondria, diminishing its interactions with HIF1α in the cytoplasm and consequently facilitating HIF1α deubiquitination and stabilization. In summary, FUNDC1-regulated mitochondrial division in hypoxic culture emerges as a critical determinant for the translocation of Parkin to mitochondria, ultimately maintaining HIF1α stabilization and promoting osteogenic differentiation.

Oxidative Stress and Cancer Therapy: Controlling Cancer Cells Using Reactive Oxygen Species

Cancer is a multifaceted disease influenced by various mechanisms, including the generation of reactive oxygen species (ROS), which have a paradoxical role in both promoting cancer progression and serving as targets for therapeutic interventions. At low concentrations, ROS serve as signaling agents that enhance cancer cell proliferation, migration, and resistance to drugs. However, at elevated levels, ROS induce oxidative stress, causing damage to biomolecules and leading to cell death. Cancer cells have developed mechanisms to manage ROS levels, including activating pathways such as NRF2, NF-κB, and PI3K/Akt. This review explores the relationship between ROS and cancer, focusing on cell death mechanisms like apoptosis, ferroptosis, and autophagy, highlighting the potential therapeutic strategies that exploit ROS to target cancer cells.

Mitophagy: insights into its signaling molecules, biological functions, and therapeutic potential in breast cancer

Mitophagy, a form of selective autophagy that removes damaged or dysfunctional mitochondria, plays a crucial role in maintaining mitochondrial and cellular homeostasis. Recent findings suggest that defective mitophagy is closely associated with various diseases, including breast cancer. Moreover, a better understanding of the multifaceted roles of mitophagy in breast cancer progression is crucial for the treatment of this disease. Here, we will summarize the molecular mechanisms of mitophagy process. In addition, we highlight the expression patterns and roles of mitophagy-related signaling molecules in breast cancer progression and the potential implications of mitophagy for the development of breast cancer, aiming to provide better therapeutic strategies for breast cancer treatment.

The tumor suppressor Parkin exerts anticancer effects through regulating mitochondrial GAPDH activity

Cancer cells preferentially utilize glycolysis for energy production, and GAPDH is a critical enzyme in glycolysis. Parkin is a tumor suppressor and a key protein involved in mitophagy regulation. However, the tumor suppression mechanism of Parkin has still not been elucidated. In this study, we identified mitochondrial GAPDH as a new substrate of the E3 ubiquitin ligase Parkin, which mediated GAPDH ubiquitination in human cervical cancer. The translocation of GAPDH into mitochondria was driven by the PINK1 kinase, and either PINK1 or GAPDH mutation prevented the accumulation of GAPDH in mitochondria. Parkin caused the ubiquitination of GAPDH at multiple sites (K186, K215, and K219) located within the enzyme-catalyzed binding domain of the GAPDH protein. GAPDH ubiquitination was required for mitophagy, and stimulation of mitophagy suppressed cervical cancer cell growth, indicating that mitophagy serves as a type of cell death. Mechanistically, PHB2 served as a key mediator in GAPDH ubiquitination-induced mitophagy through stabilizing PINK1 protein and GAPDH mutation resulted in the reduced distribution of PHB2 in mitophagic vacuole. In addition, ubiquitination of GAPDH decreased its phosphorylation level and enzyme activity and inhibited the glycolytic pathway in cervical cancer cells. The results of in vivo experiments also showed that the GAPDH mutation increased glycolysis in cervical cancer cells and accelerated tumorigenesis. Thus, we concluded that Parkin may exert its anticancer function by ubiquitinating GAPDH in mitochondria. Taken together, our study further clarified the molecular mechanism of tumor suppression by Parkin through the regulation of energy metabolism, which provides an experimental basis for the development of new drugs for the treatment of human cervical cancer.

Hypoxia Pathways in Parkinson's Disease: From Pathogenesis to Therapeutic Targets

The human brain is highly dependent on oxygen, utilizing approximately 20% of the body's oxygen at rest. Oxygen deprivation to the brain can lead to loss of consciousness within seconds and death within minutes. Recent studies have identified regions of the brain with spontaneous episodic hypoxia, referred to as "hypoxic pockets". Hypoxia can also result from impaired blood flow due to conditions such as heart disease, blood clots, stroke, or hemorrhage, as well as from reduced oxygen intake or excessive oxygen consumption caused by factors like low ambient oxygen, pulmonary diseases, infections, inflammation, and cancer. Severe hypoxia in the brain can manifest symptoms similar to Parkinson's disease (PD), including cerebral edema, mood disturbances, and cognitive impairments. Additionally, the development of PD appears to be closely associated with hypoxia and hypoxic pathways. This review seeks to investigate the molecular interactions between hypoxia and PD, emphasizing the pathological role of hypoxic pathways in PD and exploring their potential as therapeutic targets.

The interplay between mitochondrial dynamics and autophagy: From a key homeostatic mechanism to a driver of pathology

The complex relationship between mitochondrial dynamics and autophagy illustrates how two cellular housekeeping processes are intimately linked, illuminating fundamental principles of cellular homeostasis and shedding light on disparate pathological conditions including several neurodegenerative disorders. Here we review the basic tenets of mitochondrial dynamics i.e., the concerted balance between fusion and fission of the organelle, and its interplay with macroautophagy and selective mitochondrial autophagy, also dubbed mitophagy, in the maintenance of mitochondrial quality control and ultimately in cell viability. We illustrate how conditions of altered mitochondrial dynamics reverberate on autophagy and vice versa. Finally, we illustrate how altered interplay between these two key cellular processes participates in the pathogenesis of human disorders affecting multiple organs and systems.

BMSC derived EVs inhibit colorectal Cancer progression by transporting MAGI2-AS3 or something similar

In this study, we investigated the molecular mechanisms underlying the impact of extracellular vesicles (EVs) derived from bone marrow stromal cells (BMSCs) on colorectal cancer (CRC) development. The focus was on the role of MAGI2-AS3, delivered by BMSC-EVs, in regulating USP6NL DNA methylation-mediated MYC protein translation modification to promote CDK2 downregulation. Utilizing bioinformatics analysis, we identified significant enrichment of MAGI2-AS3 related to copper-induced cell death in CRC. In vitro experiments demonstrated the downregulation of MAGI2-AS3 in CRC cells, and BMSC-EVs were found to deliver MAGI2-AS3 to inhibit CRC cell proliferation, migration, and invasion. Further exploration revealed that MAGI2-AS3 suppressed MYC protein translation modification by regulating USP6NL DNA methylation, leading to CDK2 downregulation and prevention of colorectal cancer. Overexpression of MYC reversed the functional effects of BMSC-EVs-MAGI2-AS3. In vivo experiments validated the inhibitory impact of BMSC-EVs-MAGI2-AS3 on CRC tumorigenicity by promoting CDK2 downregulation through USP6NL DNA methylation-mediated MYC protein translation modification. Overall, BMSC-EVs-MAGI2-AS3 may serve as a potential intervention to prevent CRC occurrence by modulating key molecular pathways.

Reprogramming exosomes for immunity-remodeled photodynamic therapy against non-small cell lung cancer

Traditional treatments against advanced non-small cell lung cancer (NSCLC) with high morbidity and mortality continue to be dissatisfactory. Given this situation, there is an urgent requirement for alternative modalities that provide lower invasiveness, superior clinical effectiveness, and minimal adverse effects. The combination of photodynamic therapy (PDT) and immunotherapy gradually become a promising approach for high-grade malignant NSCLC. Nevertheless, owing to the absence of precise drug delivery techniques as well as the hypoxic and immunosuppressive characteristics of the tumor microenvironment (TME), the efficacy of this combination therapy approach is less than ideal. In this study, we construct a novel nanoplatform that indocyanine green (ICG), a photosensitizer, loads into hollow manganese dioxide (MnO2) nanospheres (NPs) (ICG@MnO2), and then encapsulated in PD-L1 monoclonal antibodies (anti-PD-L1) reprogrammed exosomes (named ICG@MnO2@Exo-anti-PD-L1), to effectively modulate the TME to oppose NSCLC by the synergy of PDT and immunotherapy modalities. The ICG@MnO2@Exo-anti-PD-L1 NPs are precisely delivered to the tumor sites by targeting specially PD-L1 highly expressed cancer cells to controllably release anti-PD-L1 in the acidic TME, thereby activating T cell response. Subsequently, upon endocytic uptake by cancer cells, MnO2 catalyzes the conversion of H2O2 to O2, thereby alleviating tumor hypoxia. Meanwhile, ICG further utilizes O2 to produce singlet oxygen (1O2) to kill tumor cells under 808 nm near-infrared (NIR) irradiation. Furthermore, a high level of intratumoral H2O2 reduces MnO2 to Mn2+, which remodels the immune microenvironment by polarizing macrophages from M2 to M1, further driving T cells. Taken together, the current study suggests that the ICG@MnO2@Exo-anti-PD-L1 NPs could act as a novel drug delivery platform for achieving multimodal therapy in treating NSCLC.

Role of Autophagy and AMPK in Cancer Stem Cells: Therapeutic Opportunities and Obstacles in Cancer

Cancer stem cells represent a resilient subset within the tumor microenvironment capable of differentiation, regeneration, and resistance to chemotherapeutic agents, often using dormancy as a shield. Their unique properties, including drug resistance and metastatic potential, pose challenges for effective targeting. These cells exploit certain metabolic processes for their maintenance and survival. One of these processes is autophagy, which generally helps in energy homeostasis but when hijacked by CSCs can help maintain their stemness. Thus, it is often referred as an Achilles heel in CSCs, as certain cancers tend to depend on autophagy for survival. Autophagy, while crucial for maintaining stemness in cancer stem cells (CSCs), can also serve as a vulnerability in certain contexts, making it a complex target for therapy. Regulators of autophagy like AMPK (5' adenosine monophosphate-activated protein kinase) also play a crucial role in maintaining CSCs stemness by helping CSCs in metabolic reprogramming in harsh environments. The purpose of this review is to elucidate the interplay between autophagy and AMPK in CSCs, highlighting the challenges in targeting autophagy and discussing therapeutic strategies to overcome these limitations. This review focuses on previous research on autophagy and its regulators in cancer biology, particularly in CSCs, addresses the remaining unanswered questions, and potential targets for therapy are also brought to attention.

Unraveling the Triad: Hypoxia, Oxidative Stress and Inflammation in Neurodegenerative Disorders

The mammalian brain's complete dependence on oxygen for ATP production makes it highly susceptible to hypoxia, at high altitudes or in clinical scenarios including anemia or pulmonary disease. Hypoxia plays a crucial role in the development of various brain disorders, such as Alzheimer's, Parkinson's, and other age-related neurodegenerative diseases. On the other hand, a decrease in environmental oxygen levels, such as prolonged stays at high elevations, may have beneficial impacts on the process of ageing and the likelihood of death. Additionally, the utilization of controlled hypoxia exposure could potentially serve as a therapeutic approach for age-related brain diseases. Recent findings indicate that the involvement of HIF-1α and the NLRP3 inflammasome is of significant importance in the development of Alzheimer's disease. HIF-1α serves as a pivotal controller of various cellular reactions to oxygen deprivation, exerting influence on a multitude of physiological mechanisms such as energy metabolism and inflammatory responses. The NLRP3 plays a crucial role in the innate immune system by coordinating the initiation of inflammatory reactions through the assembly of the inflammasome complex. This review examines the information pertaining to the contrasting effects of hypoxia on the brain, highlighting both its positive and deleterious effects and molecular pathways that are involved in mediating these different effects. This study explores potential strategies for therapeutic intervention that focus on restoring cellular balance and reducing neuroinflammation, which are critical aspects in addressing this severe neurodegenerative condition and addresses crucial inquiries that warrant further future investigations.

Mitophagy at the crossroads of cancer development: Exploring the role of mitophagy in tumor progression and therapy resistance

Preserving a functional mitochondrial network is crucial for cellular well-being, considering the pivotal role of mitochondria in ensuring cellular survival, especially under stressful conditions. Mitophagy, the selective removal of damaged mitochondria through autophagy, plays a pivotal role in preserving cellular homeostasis by preventing the production of harmful reactive oxygen species from dysfunctional mitochondria. While the involvement of mitophagy in neurodegenerative diseases has been thoroughly investigated, it is becoming increasingly evident that mitophagy plays a significant role in cancer biology. Perturbations in mitophagy pathways lead to suboptimal mitochondrial quality control, catalyzing various aspects of carcinogenesis, including establishing metabolic plasticity, stemness, metabolic reconfiguration of cancer-associated fibroblasts, and immunomodulation. While mitophagy performs a delicate balancing act at the intersection of cell survival and cell death, mounting evidence indicates that, particularly in the context of stress responses induced by cancer therapy, it predominantly promotes cell survival. Here, we showcase an overview of the current understanding of the role of mitophagy in cancer biology and its potential as a target for cancer therapy. Gaining a more comprehensive insight into the interaction between cancer therapy and mitophagy has the potential to reveal novel targets and pathways, paving the way for enhanced treatment strategies for therapy-resistant tumors in the near future.

Novel hypoxia-induced HIF-1αactivation in asthma pathogenesis

BACKGROUND

Asthma's complexity, marked by airway inflammation and remodeling, is influenced by hypoxic conditions. This study focuses on the role of Hypoxia-Inducible Factor-1 Alpha (HIF-1α) and P53 ubiquitination in asthma exacerbation.

METHODS

High-throughput sequencing and bioinformatics were used to identify genes associated with asthma progression, with an emphasis on GO and KEGG pathway analyses. An asthma mouse model was developed, and airway smooth muscle cells (ASMCs) were isolated to create an in vitro hypoxia model. Cell viability, proliferation, migration, and apoptosis were assessed, along with ELISA and Hematoxylin and Eosin (H&E) staining.

RESULTS

A notable increase in HIF-1α was observed in both in vivo and in vitro asthma models. HIF-1α upregulation enhanced ASMCs' viability, proliferation, and migration, while reducing apoptosis, primarily via the promotion of P53 ubiquitination through MDM2. In vivo studies showed increased inflammatory cell infiltration and airway structural changes, which were mitigated by the inhibitor IDF-11,774.

CONCLUSION

The study highlights the critical role of the HIF-1α-MDM2-P53 axis in asthma, suggesting its potential as a target for therapeutic interventions. The findings indicate that modulating this pathway could offer new avenues for treating the complex respiratory disorder of asthma.

Involvement of tumor immune microenvironment metabolic reprogramming in colorectal cancer progression, immune escape, and response to immunotherapy

Metabolic reprogramming is a k`ey hallmark of tumors, developed in response to hypoxia and nutrient deficiency during tumor progression. In both cancer and immune cells, there is a metabolic shift from oxidative phosphorylation (OXPHOS) to aerobic glycolysis, also known as the Warburg effect, which then leads to lactate acidification, increased lipid synthesis, and glutaminolysis. This reprogramming facilitates tumor immune evasion and, within the tumor microenvironment (TME), cancer and immune cells collaborate to create a suppressive tumor immune microenvironment (TIME). The growing interest in the metabolic reprogramming of the TME, particularly its significance in colorectal cancer (CRC)-one of the most prevalent cancers-has prompted us to explore this topic. CRC exhibits abnormal glycolysis, glutaminolysis, and increased lipid synthesis. Acidosis in CRC cells hampers the activity of anti-tumor immune cells and inhibits the phagocytosis of tumor-associated macrophages (TAMs), while nutrient deficiency promotes the development of regulatory T cells (Tregs) and M2-like macrophages. In CRC cells, activation of G-protein coupled receptor 81 (GPR81) signaling leads to overexpression of programmed death-ligand 1 (PD-L1) and reduces the antigen presentation capability of dendritic cells. Moreover, the genetic and epigenetic cell phenotype, along with the microbiota, significantly influence CRC metabolic reprogramming. Activating RAS mutations and overexpression of epidermal growth factor receptor (EGFR) occur in approximately 50% and 80% of patients, respectively, stimulating glycolysis and increasing levels of hypoxia-inducible factor 1 alpha (HIF-1α) and MYC proteins. Certain bacteria produce short-chain fatty acids (SCFAs), which activate CD8+ cells and genes involved in antigen processing and presentation, while other mechanisms support pro-tumor activities. The use of immune checkpoint inhibitors (ICIs) in selected CRC patients has shown promise, and the combination of these with drugs that inhibit aerobic glycolysis is currently being intensively researched to enhance the efficacy of immunotherapy.

Parkin deficiency promotes liver cancer metastasis by TMEFF1 transcription activation via TGF-β/Smad2/3 pathway

Parkin (PARK2) deficiency is frequently observed in various cancers and potentially promotes tumor progression. Here, we showed that Parkin expression is downregulated in liver cancer tissues, which correlates with poor patient survival. Parkin deficiency in liver cancer cells promotes migration and metastasis as well as changes in EMT and metastasis markers. A negative correlation exists between TMEFF1 and Parkin expression in liver cancer cells and tumor tissues. Parkin deficiency leads to upregulation of TMEFF1 which promotes migration and metastasis. TMEFF1 transcription is activated by Parkin-induced endogenous TGF-β production and subsequent phosphorylation of Smad2/3 and its binding to TMEFF1 promotor. TGF-β inhibitor and TMEFF1 knockdown can reverse shParkin-induced cell migration and changes of EMT markers. Parkin interacts with and promotes the ubiquitin-dependent degradation of HIF-1α/HIF-1β and p53, which accounts for the suppression of TGF-β production. Our data have revealed that Parkin deficiency in cancer leads to the activation of the TGF-β/Smad2/3 pathway, resulting in the expression of TMEFF1 which promotes cell migration, EMT, and metastasis in liver cancer cells.

Multi omics analysis of mitophagy subtypes and integration of machine learning for predicting immunotherapy responses in head and neck squamous cell carcinoma

Mitophagy serves as a critical mechanism for tumor cell death, significantly impacting the progression of tumors and their treatment approaches. There are significant challenges in treating patients with head and neck squamous cell carcinoma, underscoring the importance of identifying new targets for therapy. The function of mitophagy in head and neck squamous carcinoma remains uncertain, thus investigating its impact on patient outcomes and immunotherapeutic responses is especially crucial. We initially analyzed the differential expression, prognostic value, intergene correlations, copy number variations, and mutation frequencies of mitophagy-related genes at the pan-cancer level. Through unsupervised clustering, we divided head and neck squamous carcinoma into three subtypes with distinct prognoses, identified the signaling pathway features of each subtype using ssGSEA, and characterized subtype B as having features of an immune desert using various immune infiltration calculation methods. Using multi-omics data, we identified the genomic variation characteristics, mutated gene pathway features, and drug sensitivity features of the mitophagy subtypes. Utilizing a combination of 10 machine learning algorithms, we have developed a prognostic scoring model called Mitophagy Subgroup Risk Score (MSRS), which is used to predict patient survival and the response to immune checkpoint blockade therapy. Simultaneously, we applied MSRS to single-cell analysis to explore intercellular communication. Through laboratory experiments, we validated the biological function of SLC26A9, one of the genes in the risk model. In summary, we have explored the significant role of mitophagy in head and neck tumors through multi-omics data, providing new directions for clinical treatment.

The implication of serum HLA-G in angiogenesis of multiple myeloma

BACKGROUND

Despite the advances of therapies, multiple myeloma (MM) remains an incurable hematological cancer that most patients experience relapse. Tumor angiogenesis is strongly correlated with cancer relapse. Human leukocyte antigen G (HLA-G) has been known as a molecule to suppress angiogenesis. We aimed to investigate whether soluble HLA-G (sHLA-G) was involved in the relapse of MM.

METHODS

We first investigated the dynamics of serum sHLA-G, vascular endothelial growth factor (VEGF) and interleukin 6 (IL-6) in 57 successfully treated MM patients undergoing remission and relapse. The interactions among these angiogenesis-related targets (sHLA-G, VEGF and IL-6) were examined in vitro. Their expression at different oxygen concentrations was investigated using a xenograft animal model by intra-bone marrow and skin grafts with myeloma cells.

RESULTS

We found that HLA-G protein degradation augmented angiogenesis. Soluble HLA-G directly inhibited vasculature formation in vitro. Mechanistically, HLA-G expression was regulated by hypoxia-inducible factor-1α (HIF-1α) in MM cells under hypoxia. We thus developed two mouse models of myeloma xenografts in intra-bone marrow (BM) and underneath the skin, and found a strong correlation between HLA-G and HIF-1α expressions in hypoxic BM, but not in oxygenated tissues. Yet when stimulated with IL-6, both HLA-G and HIF-1α could be targeted to ubiquitin-mediated degradation via PARKIN.

CONCLUSION

These results highlight the importance of sHLA-G in angiogenesis at different phases of multiple myeloma. The experimental evidence that sHLA-G as an angiogenesis suppressor in MM may be useful for future development of novel therapies to prevent relapse.

TRIM Expression in HNSCC: Exploring the Link Between Ubiquitination, Immune Infiltration, and Signaling Pathways Through Bioinformatics

Objective

Ubiquitination is an important post-translational modification. However, the significance of the TRIM family of E3 ubiquitin ligases in head and neck squamous cell carcinoma (HNSCC) has not been determined. In this study, the roles of TRIM E3 ubiquitin ligases in lymphovascular invasion in head and neck squamous cell carcinoma (HNSCC) were evaluated.

Materials and Methods

TRIM expression and related parameters were obtained from UbiBrowser2.0, UALCAN, TIMER, TISIDB, LinkedOmics, STRING, and GeneMANIA databases. Immunohistochemistry was used to confirm their expression.

Results

TRIM2, TRIM11, TRIM28, and TRIM56 were upregulated in HNSCC with lymphovascular invasion. TRIM expression was strongly associated with immune infiltration, including key treatment targets, like PD-1 and CTL4. Co-expressed genes and possible ubiquitination substrates included tumor-related factors. The TRIMs had predicted roles in ubiquitination-related pathways and vital signaling pathways, eg, MAPK, PI3K-Akt, and JAK-STAT signaling pathways.

Conclusion

Ubiquitination mediated by four TRIMs might be involved in the regulation of tumor immunity, laying the foundation for future studies of the roles of the TRIM family on the prediction and personalized medicine in HNSCC. The four TRIMs might exert oncogenic effects by promoting lymphovascular invasion in HNSCC.

An E3 ligase TRIM1 promotes colorectal cancer progression via K63-linked ubiquitination and activation of HIF1α

Accumulating studies have shown that E3 ligases play crucial roles in regulating cellular biological processes and signaling pathways during carcinogenesis via ubiquitination. Tripartite-motif (TRIM) ubiquitin E3 ligases consist of over 70 members. However, the clinical significance and their contributions to tumorigenesis remain largely unknown. In this study, we analyzed the RNA-sequencing expression of TRIM E3 ligases in colorectal cancer (CRC) and identified 10 differentially expressed genes, among which TRIM1 expression predicted poor prognosis of CRC patients. We demonstrated that TRIM1 expression is positively associated with CRC pathological stages, and higher expression is positively correlated with infiltrating levels of immune cells and immunotherapy biomarkers. TRIM1 expression promotes the proliferation and migration of colorectal cancer cells in vitro and in vivo. Transcriptional analysis showed that TRIM1 is responsible for metabolism promotion and immune suppression. Mechanistically, we found that TRIM1 binds HIF1α and mediates its K63-linked ubiquitination, which is required for HIF1α nuclear translocation and subsequent activation. Ubiquitination occurs at Lys214 in the loop between the two PAS domains of HIF1α, and mutation of Lys214 severely disturbs the function of HIF1α. Besides, HIF1α ubiquitination enhances its binding with proteins involved in cellular trafficking and nucleocytoplasmic transport pathway. Collectively, our results indicate TRIM1's role in predicting prognosis and reveal how TRIM1 functions to upregulate HIF1α expression and promote tumor cell proliferation.

Metabolic Roles of HIF1, c-Myc, and p53 in Glioma Cells

The metabolic reprogramming that promotes tumorigenesis in glioblastoma is induced by dynamic alterations in the hypoxic tumor microenvironment, as well as in transcriptional and signaling networks, which result in changes in global genetic expression. The signaling pathways PI3K/AKT/mTOR and RAS/RAF/MEK/ERK stimulate cell metabolism, either directly or indirectly, by modulating the transcriptional factors p53, HIF1, and c-Myc. The overexpression of HIF1 and c-Myc, master regulators of cellular metabolism, is a key contributor to the synthesis of bioenergetic molecules that mediate glioma cell transformation, proliferation, survival, migration, and invasion by modifying the transcription levels of key gene groups involved in metabolism. Meanwhile, the tumor-suppressing protein p53, which negatively regulates HIF1 and c-Myc, is often lost in glioblastoma. Alterations in this triad of transcriptional factors induce a metabolic shift in glioma cells that allows them to adapt and survive changes such as mutations, hypoxia, acidosis, the presence of reactive oxygen species, and nutrient deprivation, by modulating the activity and expression of signaling molecules, enzymes, metabolites, transporters, and regulators involved in glycolysis and glutamine metabolism, the pentose phosphate cycle, the tricarboxylic acid cycle, and oxidative phosphorylation, as well as the synthesis and degradation of fatty acids and nucleic acids. This review summarizes our current knowledge on the role of HIF1, c-Myc, and p53 in the genic regulatory network for metabolism in glioma cells, as well as potential therapeutic inhibitors of these factors.

The Emerging Role of Deubiquitinases in Radiosensitivity

Radiation therapy is a primary treatment for cancer, but radioresistance remains a significant challenge in improving efficacy and reducing toxicity. Accumulating evidence suggests that deubiquitinases (DUBs) play a crucial role in regulating cell sensitivity to ionizing radiation. Traditional small-molecule DUB inhibitors have demonstrated radiosensitization effects, and novel deubiquitinase-targeting chimeras (DUBTACs) provide a promising strategy for radiosensitizer development by harnessing the ubiquitin-proteasome system. This review highlights the mechanisms by which DUBs regulate radiosensitivity, including DNA damage repair, the cell cycle, cell death, and hypoxia. Progress on DUB inhibitors and DUBTACs is summarized, and their potential radiosensitization effects are discussed. Developing drugs targeting DUBs appears to be a promising alternative approach to overcoming radioresistance, warranting further research into their mechanisms.

Association between Parkinson's Disease and Cancer: New Findings and Possible Mediators

Epidemiological evidence points to an inverse association between Parkinson's disease (PD) and almost all cancers except melanoma, for which this association is positive. The results of multiple studies have demonstrated that patients with PD are at reduced risk for the majority of neoplasms. Several potential biological explanations exist for the inverse relationship between cancer and PD. Recent results identified several PD-associated proteins and factors mediating cancer development and cancer-associated factors affecting PD. Accumulating data point to the role of genetic traits, members of the synuclein family, neurotrophic factors, the ubiquitin-proteasome system, circulating melatonin, and transcription factors as mediators. Here, we present recent data about shared pathogenetic factors and mediators that might be involved in the association between these two diseases. We discuss how these factors, individually or in combination, may be involved in pathology, serve as links between PD and cancer, and affect the prevalence of these disorders. Identification of these factors and investigation of their mechanisms of action would lead to the discovery of new targets for the treatment of both diseases.

HIF-1 contributes to autophagy activation via BNIP3 to facilitate renal fibrosis in hypoxia in vitro and UUO in vivo

The molecular basis of renal interstitial fibrosis, a major pathological feature of progressive kidney diseases, remains poorly understood. Autophagy has been implicated in renal fibrosis, but whether it promotes or inhibits fibrosis remains controversial. Moreover, it is unclear how autophagy is activated and sustained in renal fibrosis. The present study was designed to address these questions using the in vivo mouse model of unilateral ureteral obstruction and the in vitro model of hypoxia in renal tubular cells. Both models showed the activation of hypoxia-inducible factor-1 (HIF-1) and autophagy along with fibrotic changes. Inhibition of autophagy with chloroquine reduced renal fibrosis in unilateral ureteral obstruction model, whereas chloroquine and autophagy-related gene 7 knockdown decreased fibrotic changes in cultured renal proximal tubular cells, supporting a profibrotic role of autophagy. Notably, pharmacological and genetic inhibition of HIF-1 led to the suppression of autophagy and renal fibrosis in these models. Mechanistically, knock down of BCL2 and adenovirus E1B 19-kDa-interacting protein 3 (BNIP3), a downstream target gene of HIF, decreased autophagy and fibrotic changes during hypoxia in BUMPT cells. Together, these results suggest that HIF-1 may activate autophagy via BNIP3 in renal tubular cells to facilitate the development of renal interstitial fibrosis.NEW & NOTEWORTHY Autophagy has been reported to participate in renal fibrosis, but its role and underlying activation mechanism is unclear. In this study, we report the role of HIF-1 in autophagy activation in models of renal fibrosis and further investigate the underlying mechanism.

A comprehensive review on signaling attributes of serine and serine metabolism in health and disease

Serine is a metabolite with ever-expanding metabolic and non-metabolic signaling attributes. By providing one‑carbon units for macromolecule biosynthesis and functional modifications, serine and serine metabolism largely impinge on cellular survival and function. Cancer cells frequently have a preference for serine metabolic reprogramming to create a conducive metabolic state for survival and aggressiveness, making intervention of cancer-associated rewiring of serine metabolism a promising therapeutic strategy for cancer treatment. Beyond providing methyl donors for methylation in modulation of innate immunity, serine metabolism generates formyl donors for mitochondrial tRNA formylation which is required for mitochondrial function. Interestingly, fully developed neurons lack the machinery for serine biosynthesis and rely heavily on astrocytic l-serine for production of d-serine to shape synaptic plasticity. Here, we recapitulate recent discoveries that address the medical significance of serine and serine metabolism in malignancies, mitochondrial-associated disorders, and neurodegenerative pathologies. Metabolic control and epigenetic- and posttranslational regulation of serine metabolism are also discussed. Given the metabolic similarities between cancer cells, neurons and germ cells, we further propose the relevance of serine metabolism in testicular homeostasis. Our work provides valuable hints for future investigations that will lead to a deeper understanding of serine and serine metabolism in cellular physiology and pathology.

The ubiquitin codes in cellular stress responses

Ubiquitination/ubiquitylation, one of the most fundamental post-translational modifications, regulates almost every critical cellular process in eukaryotes. Emerging evidence has shown that essential components of numerous biological processes undergo ubiquitination in mammalian cells upon exposure to diverse stresses, from exogenous factors to cellular reactions, causing a dazzling variety of functional consequences. Various forms of ubiquitin signals generated by ubiquitylation events in specific milieus, known as ubiquitin codes, constitute an intrinsic part of myriad cellular stress responses. These ubiquitination events, leading to proteolytic turnover of the substrates or just switch in functionality, initiate, regulate, or supervise multiple cellular stress-associated responses, supporting adaptation, homeostasis recovery, and survival of the stressed cells. In this review, we attempted to summarize the crucial roles of ubiquitination in response to different environmental and intracellular stresses, while discussing how stresses modulate the ubiquitin system. This review also updates the most recent advances in understanding ubiquitination machinery as well as different stress responses and discusses some important questions that may warrant future investigation.

Parkin inhibits proliferation and migration of bladder cancer via ubiquitinating Catalase

PRKN is a key gene involved in mitophagy in Parkinson's disease. However, recent studies have demonstrated that it also plays a role in the development and metastasis of several types of cancers, both in a mitophagy-dependent and mitophagy-independent manner. Despite this, the potential effects and underlying mechanisms of Parkin on bladder cancer (BLCA) remain unknown. Therefore, in this study, we investigated the expression of Parkin in various BLCA cohorts derived from human. Here we show that PRKN expression was low and that PRKN acts as a tumor suppressor by inhibiting the proliferation and migration of BLCA cells in a mitophagy-independent manner. We further identified Catalase as a binding partner and substrate of Parkin, which is an important antioxidant enzyme that regulates intracellular ROS levels during cancer progression. Our data showed that knockdown of CAT led to increased intracellular ROS levels, which suppressed cell proliferation and migration. Conversely, upregulation of Catalase decreased intracellular ROS levels, promoting cell growth and migration. Importantly, we found that Parkin upregulation partially restored these effects. Moreover, we discovered that USP30, a known Parkin substrate, could deubiquitinate and stabilize Catalase. Overall, our study reveals a novel function of Parkin and identifies a potential therapeutic target in BLCA.

Genetic and pharmacologic p32-inhibition rescue CHCHD2-linked Parkinson's disease phenotypes in vivo and in cell models

BACKGROUND

Mutations in CHCHD2 have been linked to Parkinson's disease, however, their exact pathophysiologic roles are unclear. The p32 protein has been suggested to interact with CHCHD2, however, the physiological functions of such interaction in the context of PD have not been clarified.

METHODS

Interaction between CHCHD2 and p32 was confirmed by co-immunoprecipitation experiments. We studied the effect of p32-knockdown in the transgenic Drosophila and Hela cells expressing the wild type and the pathogenic variants of hCHCHD2. We further investigated the rescue ability of a custom generated p32-inhibitor in these models as well as in the human fibroblast derived neural precursor cells and the dopaminergic neurons harboring hCHCHD2-Arg145Gln.

RESULTS

Our results showed that wildtype and mutant hCHCHD2 could bind to p32 in vitro, supported by in vivo interaction between human CHCHD2 and Drosophila p32. Knockdown of p32 reduced mutant hCHCHD2 levels in Drosophila and in vitro. In Drosophila hCHCHD2 models, inhibition of p32 through genetic knockdown and pharmacological treatment using a customized p32-inhibitor restored dopaminergic neuron numbers and improved mitochondrial morphology. These were correlated with improved locomotor function, reduced oxidative stress and decreased mortality. Consistently, Hela cells expressing mutant hCHCHD2 showed improved mitochondrial morphology and function after treatment with the p32-inhibitor. As compared to the isogenic control cells, large percentage of the mutant neural precursor cells and dopaminergic neurons harboring hCHCHD2-Arg145Gln contained fragmented mitochondria which was accompanied by lower ATP production and cell viability. The NPCs harboring hCHCHD2-Arg145Gln also had a marked increase in α-synuclein expression. The p32-inhibitor was able to ameliorate the mitochondrial fragmentation, restored ATP levels, increased cell viability and reduced α-synuclein level in these cells.

CONCLUSIONS

Our study identified p32 as a modulator of CHCHD2, possibly exerting its effects by reducing the toxic mutant hCHCHD2 expression and/or mitigating the downstream effects. Inhibition of the p32 pathway can be a potential therapeutic intervention for CHCHD2-linked PD and diseases involving mitochondrial dysfunction.

Identification of gene biomarkers for brain diseases via multi-network topological semantics extraction and graph convolutional network

BACKGROUND

Brain diseases pose a significant threat to human health, and various network-based methods have been proposed for identifying gene biomarkers associated with these diseases. However, the brain is a complex system, and extracting topological semantics from different brain networks is necessary yet challenging to identify pathogenic genes for brain diseases.

RESULTS

In this study, we present a multi-network representation learning framework called M-GBBD for the identification of gene biomarker in brain diseases. Specifically, we collected multi-omics data to construct eleven networks from different perspectives. M-GBBD extracts the spatial distributions of features from these networks and iteratively optimizes them using Kullback-Leibler divergence to fuse the networks into a common semantic space that represents the gene network for the brain. Subsequently, a graph consisting of both gene and large-scale disease proximity networks learns representations through graph convolution techniques and predicts whether a gene is associated which brain diseases while providing associated scores. Experimental results demonstrate that M-GBBD outperforms several baseline methods. Furthermore, our analysis supported by bioinformatics revealed CAMP as a significantly associated gene with Alzheimer's disease identified by M-GBBD.

CONCLUSION

Collectively, M-GBBD provides valuable insights into identifying gene biomarkers for brain diseases and serves as a promising framework for brain networks representation learning.

Natural compounds modulating mitophagy: Implications for cancer therapy

Cancer is considered as the second leading cause of mortality, and cancer incidence is still growing rapidly worldwide, which poses an increasing global health burden. Although chemotherapy is the most widely used treatment for cancer, its effectiveness is limited by drug resistance and severe side effects. Mitophagy is the principal mechanism that degrades damaged mitochondria via the autophagy/lysosome pathway to maintain mitochondrial homeostasis. Emerging evidence indicates that mitophagy plays crucial roles in tumorigenesis, particularly in cancer therapy. Mitophagy can exhibit dual effects in cancer, with both cancer-inhibiting or cancer-promoting function in a context-dependent manner. A variety of natural compounds have been found to affect cancer cell death and display anticancer properties by modulating mitophagy. In this review, we provide a systematic overview of mitophagy signaling pathways, and examine recent advances in the utilization of natural compounds for cancer therapy through the modulation of mitophagy. Furthermore, we address the inquiries and challenges associated with ongoing investigations concerning the application of natural compounds in cancer therapy based on mitophagy. Overcoming these limitations will provide opportunities to develop novel interventional strategies for cancer treatment.

LUBAC promotes angiogenesis and lung tumorigenesis by ubiquitinating and antagonizing autophagic degradation of HIF1α

Hypoxia-inducible factor 1 (HIF1) is critically important for driving angiogenesis and tumorigenesis. Linear ubiquitin chain assembly complex (LUBAC), the only known ubiquitin ligase capable of catalyzing protein linear ubiquitination to date, is implicated in cell signaling and associated with cancers. However, the role and mechanism of LUBAC in regulating the expression and function of HIF1α, the labile subunit of HIF1, remain to be elucidated. Herein we showed that LUBAC increases HIF1α protein expression in cultured cells and tissues of human lung cancer and enhances HIF1α DNA-binding and transcriptional activities, which are dependent upon LUBAC enzymatic activity. Mechanistically, LUBAC increases HIF1α stability through antagonizing HIF1α decay by the chaperone-mediated autophagy (CMA)-lysosome pathway, thereby potentiating HIF1α activity. We further demonstrated that HIF1α selectively interacts with HOIP (the catalytic subunit of LUBAC) primarily in the cytoplasm. LUBAC catalyzes linear ubiquitination of HIF1α at lysine 362. Linear ubiquitination shields HIF1α from interacting with heat-shock cognate protein of 70 kDa and lysosome-associated membrane protein type 2 A, two components of CMA. Consequently, linear ubiquitination confers protection against CMA-mediated destruction of HIF1α, increasing HIF1α stability and activity. We found that prolyl hydroxylation is not a perquisite for LUBAC's effects on HIF1α. Functionally, LUBAC facilitates proliferation, clonogenic formation, invasion and migration of lung cancer cells. LUBAC also boosts angiogenesis and exacerbates lung cancer growth in mice, which are greatly compromised by inhibition of HIF1α. This work provides novel mechanistic insights into the role of LUBAC in regulating HIF1α homeostasis, tumor angiogenesis and tumorigenesis of lung cancer, making LUBAC an attractive therapeutic target for cancers.

HIF-1α signaling: Essential roles in tumorigenesis and implications in targeted therapies

The hypoxic microenvironment is an essential characteristic of most malignant tumors. Notably, hypoxia-inducible factor-1 alpha (HIF-1α) is a key regulatory factor of cellular adaptation to hypoxia, and many critical pathways are correlated with the biological activity of organisms via HIF-1α. In the intra-tumoral hypoxic environment, HIF-1α is highly expressed and contributes to the malignant progression of tumors, which in turn results in a poor prognosis in patients. Recently, it has been indicated that HIF-1α involves in various critical processes of life events and tumor development via regulating the expression of HIF-1α target genes, such as cell proliferation and apoptosis, angiogenesis, glucose metabolism, immune response, therapeutic resistance, etc. Apart from solid tumors, accumulating evidence has revealed that HIF-1α is also closely associated with the development and progression of hematological malignancies, such as leukemia, lymphoma, and multiple myeloma. Targeted inhibition of HIF-1α can facilitate an increased sensitivity of patients with malignancies to relevant therapeutic agents. In the review, we elaborated on the basic structure and biological functions of HIF-1α and summarized their current role in various malignancies. It is expected that they will have future potential for targeted therapy.

p53-responsive CMBL reprograms glucose metabolism and suppresses cancer development by destabilizing phosphofructokinase PFKP

Aerobic glycolysis is critical for cancer progression and can be exploited in cancer therapy. Here, we report that the human carboxymethylenebutenolidase homolog (carboxymethylenebutenolidase-like [CMBL]) acts as a tumor suppressor by reprogramming glycolysis in colorectal cancer (CRC). The anti-cancer action of CMBL is mediated through its interactions with the E3 ubiquitin ligase TRIM25 and the glycolytic enzyme phosphofructokinase-1 platelet type (PFKP). Ectopic CMBL enhances TRIM25 binding to PFKP, leading to the ubiquitination and proteasomal degradation of PFKP. Interestingly, CMBL is transcriptionally activated by p53 in response to genotoxic stress, and p53 activation represses glycolysis by promoting PFKP degradation. Remarkably, CMBL deficiency, which impairs p53's ability to inhibit glycolysis, makes tumors more sensitive to a combination therapy involving the glycolysis inhibitor 2-deoxyglucose. Taken together, our study demonstrates that CMBL suppresses CRC growth by inhibiting glycolysis and suggests a potential combination strategy for the treatment of CMBL-deficient CRC.

UBE3B promotes breast cancer progression by antagonizing HIF-2α degradation

Mutations in E3 ubiquitin ligase UBE3B have been linked to Kaufman Oculocerebrofacial Syndrome (KOS). Accumulating evidence indicates that UBE3B may play an important role in cancer. However, the precise role of UBE3B in cancer and the underlying mechanism remain largely uncharted. Here, we reported that UBE3B is an E3 ligase for hypoxia-inducible factor 2α (HIF-2α). Mechanically, UBE3B physically interacts with HIF-2α and promotes its lysine 63 (K63)-linked polyubiquitination, thereby inhibiting the Von Hippel-Lindau (VHL) E3 ligase complex-mediated HIF-2α degradation. UBE3B depletion inhibits breast cancer cell proliferation, colony formation, migration, and invasion in vitro and suppresses breast tumor growth and lung metastasis in vivo. We further identified K394, K497, and K503 of HIF-2α as key ubiquitination sites for UBE3B. K394/497/503R mutation of HIF-2α dramatically abolishes UBE3B-mediated breast cancer growth and lung metastasis. Intriguingly, the protein levels of UBE3B are upregulated and positively correlated with HIF-2α protein levels in breast cancer tissues. These findings uncover a critical mechanism underlying the role of UBE3B in HIF-2α regulation and breast cancer progression.

Function, mechanism and drug discovery of ubiquitin and ubiquitin-like modification with multiomics profiling for cancer therapy

Ubiquitin (Ub) and ubiquitin-like (Ubl) pathways are critical post-translational modifications that determine whether functional proteins are degraded or activated/inactivated. To date, >600 associated enzymes have been reported that comprise a hierarchical task network (e.g., E1-E2-E3 cascade enzymatic reaction and deubiquitination) to modulate substrates, including enormous oncoproteins and tumor-suppressive proteins. Several strategies, such as classical biochemical approaches, multiomics, and clinical sample analysis, were combined to elucidate the functional relations between these enzymes and tumors. In this regard, the fundamental advances and follow-on drug discoveries have been crucial in providing vital information concerning contemporary translational efforts to tailor individualized treatment by targeting Ub and Ubl pathways. Correspondingly, emphasizing the current progress of Ub-related pathways as therapeutic targets in cancer is deemed essential. In the present review, we summarize and discuss the functions, clinical significance, and regulatory mechanisms of Ub and Ubl pathways in tumorigenesis as well as the current progress of small-molecular drug discovery. In particular, multiomics analyses were integrated to delineate the complexity of Ub and Ubl modifications for cancer therapy. The present review will provide a focused and up-to-date overview for the researchers to pursue further studies regarding the Ub and Ubl pathways targeted anticancer strategies.

Low expression of PINK1 and PARK2 predicts poor prognosis in patients with esophageal squamous cell carcinoma

BACKGROUND

The Parkinson's disease (PD) gene family expression is strongly linked to tumor development and progression; PINK1 and PARK2 are essential members of the PD gene family. However, the relationship between PINK1 and PARK2 and esophageal squamous cell carcinoma (ESCC) remains unknown. This research aims to clarify the prognostic value of PINK1 and PARK2 in ESCC.

METHODS

PINK1 and PARK2 protein levels in 232 ESCC specimens, and 125 matched adjacent normal tissues were detected by immunohistochemistry. The relationship between PINK1 and PARK2 protein expression and clinicopathological features were analyzed. Kaplan-Meier survival analysis was performed to estimate the prognostic value of the PINK1 and PARK2 proteins in patients. Cox univariate and multivariate analyses were used to assess the risk factors affecting the OS for patients with ESCC.

RESULTS

PINK1 and PARK2 had low expression in ESCC. Patients with low PINK1 had worse differentiation and advanced T and TNM stages. Lower PARK2 expression was linked to lymph node metastases and an advanced TNM stage. Furthermore, reduced PINK1 and PARK2 levels were associated with a poor prognosis for ESCC. Cox univariate and multivariate analyses revealed that PINK1, PARK2, and tumor size were closely associated with the prognosis of patients with ESCC, and PARK2 was an independent risk factor for patients with ESCC. Finally, the PINK1 and PARK2 proteins were closely related and shared the same signal pathway.

CONCLUSIONS

PINK1 and PARK2 could work as tumor suppressors in ESCC and are likely to become new treatment targets for ESCC.

Baohuoside I inhibits resistance to cisplatin in ovarian cancer cells by suppressing autophagy via downregulating HIF-1α/ATG5 axis

Since chemotherapy's therapeutic impact is diminished by drug resistance, treating ovarian cancer is notably challenging. Thereafter, it is critical to develop cutting-edge approaches to treating ovarian cancer. Baohuoside I (derived from Herba Epimedii) is reported to have antitumor properties in various malignancies. It is unknown, however, what role Baohuoside I plays in cisplatin (DDP)-resistant ovarian cancer cells. 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT), colony formation, and flow cytometry assay were used to investigate the impact of Baohuoside I on ovarian cancer A2780 cells and DDP-resistant A2780 (A2780/DDP) cells. The level of microtubule associated protein 1 light chain 3 (LC3) was determined using immunofluorescence staining. Utilizing the mRFP-GFP-LC3B tandem fluorescent probe allowed us to analyse the autophagy flux. Analysis of mRNA and protein level was performed using RT-qPCR and Western blot analysis, respectively. The interaction between hypoxia inducible factor 1 subunit alpha (HIF-1α) and autophagy related 5 (ATG5) promoter was investigated by dual luciferase and ChIP assay. Additionally, evaluation of Baohuoside I's role in ovarian cancer was performed using a nude mouse xenograft model. Baohuoside I decreased the viability and proliferation and triggered the apoptosis of both A2780 and A2780/DDP cells in a concentration-dependent manner. Baohuoside I also increased the sensitivity of A2780/DDP cells to DDP. Concurrently, HIF-1α could promote A2780/DDP cells resistance to DDP. In addition, HIF-1α could induce the autophagy of A2780/DDP cells through transcriptionally activating ATG5, and Baohuoside I imporved the chemosensitivity of A2780/DDP cells to DDP by downregulating HIF-1α. Moreover, Baohuoside I could inhibit the chemoresistance to DDP in ovarian cancer in vivo. Baohuoside I sensitizes ovarian cancer cells to DDP by suppressing autophagy via downregulating the HIF-1α/ATG5 axis. Consequently, Baohuoside I might be evaluated as a new agent for enhancing the chemotherapeutic efficacy of drug treatment for ovarian cancer.

14-3-3σ-NEDD4L axis promotes ubiquitination and degradation of HIF-1α in colorectal cancer

A hypoxic microenvironment contributes to tumor progression, with hypoxia-inducible factor-1α (HIF-1α) being a critical regulator. We have reported that 14-3-3σ is negatively associated with HIF-1α expression; however, its role in hypoxia-induced tumor progression remains poorly characterized. Here we show that 14-3-3σ suppresses cancer hypoxia-induced metastasis and angiogenesis in colorectal cancer (CRC). 14-3-3σ opposes HIF-1α expression by regulating the protein stability of HIF-1α, thereby decreasing HIF-1α transcriptional activity and suppressing tumor progression. Mechanistic studies show that the 14-3-3σ-interacting protein neural precursor cell-expressed developmentally down-regulated 4-like (NEDD4L) is an E3 ligase that targets HIF-1α. 14-3-3σ promotes the binding of S448-phosphorylated NEDD4L to HIF-1α, thereby enhancing HIF-1α poly-ubiquitination and subsequent proteasome-mediated degradation. Consistent with this anti-tumorigenic function for 14-3-3σ, low 14-3-3σ expression levels correlate with poor CRC patient survival, and 14-3-3σ enhances the response of CRC to bevacizumab. These results reveal an important mechanism for 14-3-3σ in tumor suppression through HIF-1α regulation.

Mitochondria in endothelial cells angiogenesis and function: current understanding and future perspectives

Endothelial cells (ECs) angiogenesis is the process of sprouting new vessels from the existing ones, playing critical roles in physiological and pathological processes such as wound healing, placentation, ischemia/reperfusion, cardiovascular diseases and cancer metastasis. Although mitochondria are not the major sites of energy source in ECs, they function as important biosynthetic and signaling hubs to regulate ECs metabolism and adaptations to local environment, thus affecting ECs migration, proliferation and angiogenic process. The understanding of the importance and potential mechanisms of mitochondria in regulating ECs metabolism, function and the process of angiogenesis has developed in the past decades. Thus, in this review, we discuss the current understanding of mitochondrial proteins and signaling molecules in ECs metabolism, function and angiogeneic signaling, to provide new and therapeutic targets for treatment of diverse cardiovascular and angiogenesis-dependent diseases.

The ubiquitin-proteasome system in breast cancer

Ubiquitin-proteasome system (UPS) is a selective proteolytic system that is associated with the expression or function of target proteins and participates in various physiological and pathological processes of breast cancer. Inhibitors targeting the 26S proteasome in combination with other drugs have shown promising therapeutic effects in the clinical treatment of breast cancer. Moreover, several inhibitors/stimulators targeting other UPS components are also effective in preclinical studies, but have not yet been applied in the clinical treatment of breast cancer. Therefore, it is vital to comprehensively understand the functions of ubiquitination in breast cancer and to identify potential tumor promoters or tumor suppressors among UPS family members, with the aim of developing more effective and specific inhibitors/stimulators targeting specific components of this system.

E3 ubiquitin ligases in cancer stem cells: key regulators of cancer hallmarks and novel therapeutic opportunities

BACKGROUND

Human malignancies are composed of heterogeneous subpopulations of cancer cells with phenotypic and functional diversity. Among them, a unique subset of cancer stem cells (CSCs) has both the capacity for self-renewal and the potential to differentiate and contribute to multiple tumor properties. As such, CSCs are promising cellular targets for effective cancer therapy. At the molecular level, hyper-activation of multiple stemness regulatory signaling pathways and downstream transcription factors play critical roles in controlling CSCs establishment and maintenance. To regulate CSC properties, these stemness pathways are controlled by post-translational modifications including, but not limited to phosphorylation, acetylation, methylation, and ubiquitination.

CONCLUSION

In this review, we focus on E3 ubiquitin ligases and their roles and mechanisms in regulating essential hallmarks of CSCs, such as self-renewal, invasion and metastasis, metabolic reprogramming, immune evasion, and therapeutic resistance. Moreover, we discuss emerging therapeutic approaches to eliminate CSCs through targeting E3 ubiquitin ligases by chemical inhibitors and proteolysis-targeting chimera (PROTACs) which are currently under development at the discovery, preclinical, and clinical stages. Several outstanding issues such as roles for E3 ubiquitin ligases in heterogeneity and phenotypical/functional evolution of CSCs remain to be studied under pathologically and clinically relevant conditions. With the rapid application of functional genomic and proteomic approaches at single cell, spatiotemporal, and even single molecule levels, we anticipate that more specific and precise functions of E3 ubiquitin ligases will be delineated in dictating CSC properties. Rational design and proper translation of these mechanistic understandings may lead to novel therapeutic modalities for cancer procession medicine.