Journal of Biomedical Science最新文献

Aging has become an important public health concern with the accelerated aging of the global population. The rising impetus to extend lifespan as well as healthspan has drawn attention to the gut microbiome, an indispensable yet modifiable determinant of the aging process. This narrative review addresses the complex interaction between the gut microbiome and aging, synthesizing findings in logical order. Evidence from model organisms supports the causal influence of gut microbes on host aging and longevity. Developmental evolution of the human gut microbiome throughout life stages reflects its adaptive nature affected by diet, lifestyle, hormone levels, and immune function, regulating aging through the gut-muscle and the gut-brain axes in late life. Signature characteristics of the long-lived gut microbiome, including increased diversity, elevated beneficial taxa, and enhanced gut homeostasis, lead to strategies to extend longevity. Intake of fiber, regular exercise, and pro-/pre-/postbiotic supplements are potential interventions on the gut microbiome to foster vitality in later years. Centering on these connected topics, this review identifies questions warranting investigation, with potential to improve therapeutic strategies for healthy aging.

Background: Programmed death-ligand 1 (PD-L1) is a well-recognized predictive biomarker for immunotherapy in non-oncogene-addicted non-small cell lung cancer (NSCLC). However, its role in epidermal growth factor receptor (EGFR)-mutant NSCLC remains unclear. This study aims to investigate the impact of PD-L1 on the signaling pathways in EGFR-mutant NSCLC.

Methods: The regulatory role of PD-L1 was investigated through in vitro manipulation of PD-L1 expression across several EGFR-mutant cell lines, followed by analysis via human receptor tyrosine kinase (RTK) array, Western blotting, protein tyrosine phosphatase (PTPs) activity assays, and mRNA expression profiling. In vivo experiments were carried out using xenograft mice implanted with parental, PD-L1 knock-out and PD-L1 overexpression NCI-H1975 cells. Osimertinib was orally administered to the mice until tumor progression to evaluate the impact of PD-L1 on osimertinib resistance.

Results: In human RTK array screening, c-MET phosphorylation was found to be increased in EGFR-mutant PD-L1 overexpressing cells. We found that PD-L1 overexpression upregulated c-MET phosphorylation, while PD-L1 knock-out and knock-down resulted in downregulation of c-MET phosphorylation. Furthermore, we showed that PD-L1 upregulates c-MET phosphorylation by suppressing PTP activity and reducing mRNA expression in selected PTPs. In xenograft mice, MET amplification only developed in PD-L1 overexpression, but not in PD-L1 knock-out and parental NCI-H1975 cells, at the time of osimertinib resistance.

Conclusion: In EGFR-mutant NSCLC, PD-L1 regulates c-MET phosphorylation and promotes MET amplification, contributing to osimertinib resistance.

Dietary restriction (DR) refers to a broad set of interventions that limit the intake of specific nutrients or overall food consumption, either in quantity or timing, without causing malnutrition. DR has long been considered the most robust intervention for increasing healthspan and lifespan. This includes, not exhaustively, caloric restriction (CR), protein restriction (PR), amino acid restriction (AAR), intermittent fasting (IF), and time-restricted fasting (TRF), each with overlapping but distinct metabolic and physiological effects. This brief review examines the current scientific understanding of how some of the most commonly employed DR regimens may impact metabolism, lifespan, and healthspan. Particular attention is given to the underlying biological mechanisms and supporting evidence derived from both human clinical studies and fundamental biological research conducted with model organisms ranging from yeast to non-human primates.

Background: While the Warburg effect links glycolysis to de novo lipid synthesis in carcinogenesis, the roles of lipids in cancer prognosis remain elusive. Here, a multi-omics approach was conducted in a cohort of hepatocellular carcinoma (HCC) to elucidate the role of lipid metabolites as prognostic markers.

Methods: Ninety-eight HCC patients were recruited between 2011 and 2013. Their specimens were subjected to transcriptomic and lipidomic profiling. The resulting data were then analyzed using strategic bioinformatics approaches to identify associations with HCC prognosis. Subsequently, lipid-related pathways implicated in these analyses were verified using cellular and molecular approaches.

Results: Our findings indicate that lipidomic profiling is a potential prognostic marker for HCC. Specifically, higher levels of ether-lipids were significantly associated with poor survival and adverse clinical features, such as advanced TNM stage and metastasis. Analysis of transcriptomic patterns within patient groups defined by lipidomic profiles revealed that ether-lipid abundance inversely correlated with PPAR signaling but positively correlated with the expression of metastasis-associated gene clusters (e.g., genes involved in ECM remodeling, adhesion, and migration). Functional studies verified that ether-lipids enhance cell mobility. Consistent with the proposed mechanism, treatment with a PPARα agonist reduced ether-lipid accumulation and cell mobility. Therefore, we delineated an axis whereby PPARα downregulation leads to ether-lipid accumulation, subsequently promoting cell mobility. Mechanistically, we propose that deficient PPARα-mediated lipophagy results in cellular ether-lipid accumulation. These lipids, in turn, promote cell mobility via Transient Receptor Potential Vanilloid 2 (TRPV2)-mediated cytoskeletal rearrangement.

Conclusion: This study identifies lipidome patterns as a risk factor for patient prognosis. Mechanistically, deficient PPARα-mediated lipophagy leads to the accumulation of ether-lipids within cancer cells, which in turn promotes cell mobility via calcium-dependent, TRPV2 channel-mediated cytoskeletal rearrangement.

Background: PPM1D (protein phosphatase Mg²⁺/Mn²⁺ dependent 1D) is a Ser/Thr phosphatase that negatively regulates p53 and functions as an oncogenic driver. Its gene amplification and overexpression are frequently observed in various malignancies and disruption of PPM1D degradation has also been reported as a cause of cancer progression. However, the precise mechanisms regulating PPM1D stability remain to be elucidated.

Methods: PPM1D stability and degradation pathways were examined using cycloheximide chase assays in multiple cell lines. Proteasome and lysosome inhibitors were used to determine the degradation mechanism, while ubiquitination dependency was assessed using TAK-243, an E1 ubiquitin-activating enzyme inhibitor. In vitro degradation assays with purified 20S proteasome were performed to evaluate direct proteasomal degradation. Immunoprecipitation followed by mass spectrometry was performed to identify proteasomal regulators of PPM1D, with their functional roles validated through knockdown experiments. Finally, cell viability assays were conducted to assess the therapeutic potential of combined proteasome and PPM1D inhibition.

Results: Cycloheximide chase assays demonstrated that wild-type PPM1D is a short-lived protein, whereas a C-terminal truncation mutant exhibits increased stability. PPM1D undergoes rapid, ubiquitin-independent proteasomal degradation via its C-terminal 35 amino acid residues. Additionally, the region spanning residues 450-501 is necessary for ubiquitination-mediated suppression of the ubiquitin-independent degradation pathway. We also found that PPM1D is directly degraded by the 20S proteasome, with the regulatory proteasome subunits PSMD14 and PSME3 acting as activators in this process. Proteasome inhibition resulted in PPM1D accumulation, potentially reducing therapeutic efficacy. Combined proteasome and PPM1D inhibition synergistically enhanced the antitumor effect.

Conclusions: The rapid degradation of the cancer driver PPM1D is achieved through direct recognition by the proteasome, and proteasome inhibitors may reduce therapeutic efficacy due to the accumulation of PPM1D. PPM1D may serve as a suitable model substrate for elucidating the mechanism of ubiquitin-independent proteasomal degradation and represents a potential novel therapeutic target for cancer treatment based on proteasome inhibition.

Oncometabolites are aberrant metabolic byproducts that arise from mutations in enzymes of the tricarboxylic acid (TCA) cycle or related metabolic pathways and play central roles in tumor progression and immune evasion. Among these, 2-hydroxyglutarate (2-HG), succinate, and fumarate are the most well-characterized, acting as competitive inhibitors of α-ketoglutarate-dependent dioxygenases to alter DNA and histone methylation, cellular differentiation, and hypoxia signaling. More recently, itaconate, an immunometabolite predominantly produced by activated macrophages, has been recognized for its dual roles in modulating inflammation and tumor immunity. These metabolites influence cancer development through multiple mechanisms, including epigenetic reprogramming, redox imbalance, and post-translational protein modifications. Importantly, their effects are not limited to cancer cells but extend to various components of the tumor microenvironment, such as T cells, macrophages, dendritic cells, and endothelial cells, reshaping immune responses and contributing to immune suppression. In this review, we highlight the emerging insights into the roles of TCA cycle-associated oncometabolites in cancer biology and immune regulation. We discuss how these metabolites impact both tumor-intrinsic processes and intercellular signaling within the tumor microenvironment. Finally, we examine therapeutic strategies targeting oncometabolite pathways, including mutant IDH inhibitors, α-ketoglutarate mimetics, and immunometabolic interventions, with the goal of restoring immune surveillance and improving cancer treatment outcomes.

Background: Enteroviruses, including Coxsackie B (CVB) viruses, can cause severe diseases such as myocarditis, pancreatitis, and meningitis. Vaccines can prevent these complications, but conserved non-neutralizing epitopes in the viral capsid may limit their effectiveness. The immunodominant PALXAXETG motif, located in the VP1 N-terminus, is a highly conserved region in enteroviruses that elicits non-neutralizing antibody responses. Virus-like particles (VLPs) offer a safe and effective vaccine platform because of their structural similarity to native viruses but lack viral genetic material. Importantly, VLPs can be structurally modified to exclude specific epitopes.

Methods: Here, we produced a modified CVB1 virus-like particle (VLP) vaccine lacking 15 amino acids from the PALXAXETG motif (designated VLPΔpalxa) using the baculovirus-insect cell expression system. To confirm the structural integrity, we determined the crystal structure of the modified VLP with 3.2 Å resolution. We then conducted comprehensive immunogenicity studies in mice, including dose titration, comparison of two versus three immunizations, and post-vaccination viral challenge. In addition, we evaluated the impact of the AS04 adjuvant on the immunogenicity of unmodified and modified CVB1-VLP vaccines and the formalin-inactivated CVB1 vaccine.

Results: The yield of CVB1-VLPΔpalxa was 29.5 mg/L, and the particles were shown to assemble similarly to unmodified CVB1-VLP. CVB1-VLPΔpalxa induced robust antibody responses, with neutralizing antibody titres comparable to or exceeding those elicited by unmodified VLP or inactivated virus vaccines. A 2 µg dose was identified as optimal, providing the highest neutralizing antibody titres. A third immunization significantly increased antibody levels, and all non-adjuvanted vaccines protected the mice from CVB1 challenge after the third dose. The addition of AS04 significantly enhanced the antibody response, particularly in both VLP groups.

Conclusions: We demonstrated that with targeted structural modification of the CVB1-VLP capsid, immunodominant antibody responses against the conserved PALXAXETG motif can be avoided. We demonstrate that structural modification of CVB1-VLP is a viable strategy. Since the deleted epitope is known to be non-neutralizing, its deletion may help focus the immune response on more protective targets and thereby improve vaccine efficacy. The modified VLPs, particularly when adjuvanted, offer a promising approach for developing safe and effective enterovirus vaccines.

Background: Exposure of mammals to ototoxic compounds causes hair cell (HC) loss in the vestibular sensory epithelia of the inner ear. In chronic exposure models, this loss often occurs by extrusion of the HC from the sensory epithelium towards the luminal cavity. HC extrusion is preceded by several steps that begin with detachment and synaptic uncoupling of the cells from the afferent terminals of their postsynaptic vestibular ganglion neurons. The purpose of this study was to identify gene expression mechanisms that drive these responses to chronic ototoxic stress.

Methods: We conducted four RNA-seq experiments that generated five comparisons of control versus treated animals. These involved two species (rat and mouse), two compounds (streptomycin and 3,3'-iminodipropionitrile, IDPN), and three time points in our rat/IDPN model. We compared differentially expressed genes and their associated Gene Ontology terms, and several genes of interest were validated by in-situ hybridisation and immunofluorescence analyses.

Results: Common and model-unique expression responses were identified. The earliest and most robust common response was downregulation of HC-specific genes, including stereocilium (Atp2b2, Xirp2), synaptic (Nsg2), and ion channel genes (Kcnab1, Kcna10), together with new potential biomarkers of HC stress (Vsig10l2). A second common response across species and compounds was the upregulation of the stress mediator Atf3. Model- or time-restricted responses included downregulation of cell-cell adhesion and mitochondrial ATP synthesis genes, and upregulation of the interferon response, unfolded protein response, and tRNA aminoacylation genes.

Conclusions: The present results provide key information on the responses of the vestibular sensory epithelium to chronic ototoxic stress, potentially relevant to other types of chronic stress.

Extracellular vesicles (EVs) are heterogeneous populations of membrane-bound particles released from almost all cell types in an organism and play pivotal roles in cell-cell communication. EVs carry nucleic acids, proteins, metabolites and other bioactive substances, which are taken by the recipient cells to alter cell physiology and functions. The cargo landscapes of EVs are influenced by the cell contexts and the biogenesis mechanisms of EVs, in which certain molecules govern both biogenesis and cargo sorting. In this review, we discuss the biogenesis and secretion mechanisms of various types of EVs, including several atypical EVs. In addition, given that the tumor immune microenvironment (TIME) is intricately controlled by the communication between tumor cells and various immune cells, we summarize the latest update about how tumor-derived EVs influence the phenotypes of various immune cells in tumor microenvironment for tumor immune evasion, and, conversely, how EVs secreted from immune cells in TIME control the malignancies of tumor cells. In particular, we discuss the roles of several atypical EVs in regulating TIME. Lastly, we highlight the advantages of utilizing EVs as liquid biopsies for cancer diagnosis, the application and challenge of EVs in different anti-tumor therapies, and the recent clinical trials that exploit EVs as drug carriers. As the continuous advances in our understanding of the complex biogenesis mechanisms and the pleiotropic actions of EVs in TIME as well as the technology improvements in harnessing EVs' clinical benefits, we can expect to further unlock the biomedical potential of EVs in cancer and other diseases.