ObjectiveMethylthioadenosine phosphorylase (MTAP) is found to be frequently deleted in malignant cancers, but the role of MTAP underlying metastasis and stemness of liver cancer remains far from clear. 5-fluorouracil (5-Fu) is clinically used in treating advanced liver cancer, however, chemoresistance is one of the major barriers impeding its efficacy. Liver cancer stem cells are considered to be the reservoir for tumor progression and chemoresistance. This study aims to explore the role of MTAP in regulating stemness and chemoresistance of 5-Fu in liver cancer. It is designed to elucidate the molecular mechanisms underlying MTAP-manipulated stemness. How MTAP influences metastasis and chemoresistance against 5-Fu in liver cancer is also elaborated.MethodsThe correlation of MTAP expression with stemness marker CD133 was evaluated by flow cytometry. Colony formation assays were conducted to analyze the tumorigenic ability. Western blot assays were applied to delineate the molecular mechanisms underlying MTAP-regulated stemness. Trans-well assays were conducted to analyze the metastatic potential of liver cancer cells. In vivo experiments were performed using subcutaneous xenograft and lung metastasis model on nude mice. Tumor size and weight were analyzed upon 5-Fu treatment. Metastatic nodules on lungs were evaluated. Immunohistochemical and TUNNEL assays were performed on slides obtained from tumor tissues.ResultsMTAP overexpression inhibited expression of CD133 and colony formation, which is further ablated by MTAP inhibitor. MTAP deprivation augmented stemness and colony formation, which is reversed by protein arginine methyltransferase 5 (PRMT5) overexpression but not its catalytically inactive counterparts. Critically, SRY-box transcription factor 2 (SOX2) was found to be a downstream regulator of MTAP/PRMT5, leading to stemness of liver cancer cells. MTAP overexpression suppressed SOX2 expression, while MTAP inhibition augmented expression of SOX2. Critically, MTAP overexpression inhibited migration and invasion of liver cancer cells. In vivo experiments in animal model found that MTAP deprivation promotes tumor growth and metastatic nodules of liver cancer. Additionally, MTAP overexpression inhibits tumor growth. Moreover, MTAP deprivation contributes to chemoresistance shown by increased tumor size and weight treated by 5-Fu. In contrast, MTAP overexpression led to further decline in tumor size and weight elicited by 5-Fu treatment. Accordingly, SOX2 was inhibited in tumor tissues after MTAP overexpression. Marker of proliferation Ki67 (Ki67) expression was dampened while apoptosis was found in MTAP-overexpressed tumor tissues.ConclusionIn this study, plethora of experimental studies collectively demonstrated that MTAP deprivation enhances stemness of liver cancer by regulating SOX2, exerting anti-cancer and chemoresistant role against 5-Fu in liver cancer. It is also worth noting that MTAP inhibition promoted metastasis of liver cancer. MTAP overexpression augmented tumor shrinking elicited by 5-Fu and SOX2 was involved in this process. These results concluded that MTAP/PRMT5/SOX2 signaling axis was involved in regulating stemness and chemoresistance of liver cancer. These findings help to exploit novel therapies by targeting stemness in MTAP-depleted liver cancer. It shed novel light on unveiling MTAP-regulated stemness in antagonizing 5-Fu treatment in liver cancer. It also adds mounting evidence to the theoretical basis for accomplishing personalized chemotherapy of liver cancer patients by targeting MTAP or its downstream PRMT5/SOX2.
During habitation on low-Earth-orbit (LEO) space stations, astronauts are exposed to a combination of orbital microgravity, space radiation, an enclosed and artificially controlled cabin environment, altered sleep-wake rhythms, and sustained operational and psychosocial demands. These factors can modify sensorimotor inputs, body-fluid distribution, arousal state, and task-related neural processing, thereby affecting brain function and behavior. Because evidence from real spaceflight remains limited by small samples, heterogeneous mission durations, and different measurement time points, this review integrates findings from real human spaceflight with relevant ground-based analog studies while treating real orbital studies as the primary source of evidence. We focus on electroencephalography (EEG) and event-related potentials (ERPs), structural and functional neuroimaging, and sensorimotor and cognitive outcomes, with particular attention to the direction, anatomical distribution, temporal course, and possible physiological significance of the reported changes. EEG studies indicate that long-duration spaceflight is associated with increased resting-state beta activity, particularly in sensorimotor and frontotemporal regions, together with state-dependent alterations in beta-band functional connectivity. In contrast, alpha source power and functional connectivity associated with the default mode network are reduced during long-duration missions, and some of these effects may persist into the early postflight period. Task-related electrophysiological findings further suggest that sustained mental workload can weaken frontocentral theta-temporoparietal gamma phase-amplitude coupling, whereas in-flight decision-making is accompanied by reduced P300 amplitude and reorganization of feedback-related potentials. Short-duration missions, however, have shown relative preservation of posterior dominant rhythms and some ERP measures, indicating that mission duration, recording state, and task demands substantially influence the observed electrophysiological phenotype. Neuroimaging provides complementary evidence at structural and network levels. Long-duration spaceflight has been associated with upward brain displacement, ventricular and cerebrospinal fluid expansion, regional gray- and white-matter remodeling, and alterations in white-matter structural connectivity. Functional magnetic resonance imaging (fMRI) studies further indicate reorganization of vestibular-sensorimotor, visual, and default mode networks. Some network changes recover after return to Earth, whereas others may remain detectable for months. Importantly, most MRI measurements are obtained after landing rather than in orbit; therefore, postflight findings may reflect a mixture of in-flight adaptation, the rapid transition back to 1 g, and subsequent readaptation rather than a single spaceflight effect. Behavioral evidence is most consistent for sensorimotor function. Early after return, astronauts frequently show impaired postural control, gait, spatial orientation, and coordination, consistent with reweighting among vestibular, visual, and proprioceptive information. By comparison, simple cognition and some critical operational tasks are often preserved. More subtle or high-load processes-including sustained attention, feedback evaluation, temporal processing, error monitoring, and metacognitive calibration may be more sensitive than global cognitive performance. This dissociation between neural change and preserved behavior suggests that altered brain activity should not automatically be interpreted as functional deterioration. Integrating the available modalities, we propose that LEO space-station habitation is better characterized by system-specific and stage-dependent neural adaptation than by a generalized increase or decline in brain function. The most coherent cross-modal pattern involves sensorimotor reorganization: reduced gravitational reference and weight-bearing feedback under microgravity may drive reweighting of vestibular, visual, and proprioceptive inputs, accompanied by changes in beta activity and vestibular-sensorimotor networks and followed by transient postflight sensorimotor deficits. A second major process involves fluid-related structural remodeling, in which cephalad fluid shifts and altered hydrostatic gradients may contribute to changes in cerebrospinal fluid spaces, ventricular volume, and brain tissue configuration. Resting-state and cognitive electrophysiological changes likely represent additional adjustments in network regulation and resource allocation, but their functional interpretation remains more dependent on sleep, workload, recording conditions, and individual differences. Future studies should move beyond isolated pre-post comparisons and group averages toward standardized longitudinal designs spanning preflight, multiple in-flight time points, and postflight recovery. Synchronized assessment of brain function, behavior, sleep, and key environmental parameters should be used to characterize individual adaptation trajectories and determine which neural changes reflect successful compensation, which predict delayed recovery, and which have genuine value for brain-health risk prediction and individualized countermeasures.
Ischemic stroke accounts for approximately 80% of all stroke cases worldwide and remains a leading cause of long‑term neurological disability and mortality. Intravenous thrombolysis and endovascular thrombectomy constitute the mainstay of acute reperfusion therapies, yet their clinical utility is severely constrained by narrow therapeutic time windows. Even when large‑vessel recanalization is successfully achieved, a considerable proportion of patients still suffer poor functional outcomes due to futile reperfusion and ischemia‑reperfusion injury. Historically, preclinical studies have largely focused on direct neuronal protection against calcium overload, oxidative stress and ferroptosis. Unfortunately, most promising neuroprotective agents that exhibited robust benefits in rodent models have failed to demonstrate satisfactory efficacy in phase‑Ⅱ and phase‑Ⅲ clinical trials. One critical contributor to such translational failure is the disregard for the pathological disturbance within the cerebral vascular microenvironment. Instead of merely regarding neuronal death as an autonomous cellular event, accumulating evidence indicates that sequential biochemical disruption of perivascular microenvironment acts as an initiating amplifier that propagates damage toward brain parenchyma after ischemic insult. The cerebral vascular microenvironment centers on brain microvessels and comprises endothelial cells, endothelial glycocalyx, basement membrane, pericytes, astrocytic end‑feet, perivascular microglia, as well as interstitial ions, inflammatory mediators, reactive oxygen species and extracellular matrix components. Distinct from the concept of neurovascular unit which emphasizes functional coupling between neurons, glia and vessels, the vascular microenvironment highlights dynamic biochemical homeostasis in perivascular interstitial space. Following cerebral ischemia, injured brain tissue can be spatially divided into the irreversibly damaged infarct core, metabolically‑stressed ischemic penumbra and mildly‑affected peripheral regions. These three zones lack rigid anatomical boundaries and evolve dynamically depending on reperfusion timing, presenting divergent features in blood perfusion, blood‑brain barrier integrity, cellular viability and immune‑inflammatory profiles. Four interrelated pathological cascades jointly disrupt microenvironmental homeostasis: calcium‑overload‑triggered cytotoxic cascades; blood‑brain barrier breakdown resulting from glycocalyx shedding, tight‑junction dissociation and matrix metalloproteinase‑driven basement‑membrane degradation; inflammatory‑immune dysregulation dominated by microglial phenotypic reprogramming; and mutual crosstalk between coagulation disturbance and neuroinflammation that exacerbates secondary brain injury. Multiple molecular layers orchestrate these pathological alterations. Excessive activation of HIF‑1α, NF‑κB and MAPK/ERK signaling pathways promotes barrier leakage, pro‑inflammatory factor secretion and extracellular‑matrix remodeling. Epigenetic modulation mediated by non‑coding RNAs including miRNAs and lncRNAs reshapes vascular microenvironment via three major patterns: modulating endothelial‑pericyte barrier integrity, switching microglia‑astrocyte inflammatory phenotypes, and driving metabolic reprogramming among multiple cell populations within microdomains. In addition, metabolic shift toward glycolysis among endothelial cells, microglia, astrocytes and compromised neurons establishes self‑amplifying vicious cycles of energy depletion and oxidative stress in perivascular niches. Targeted theranostic approaches oriented toward vascular microenvironment bring new opportunities for precision medicine of ischemic stroke. Magnetic nanoprobes and near‑infrared fluorescent probes respond to elevated reactive oxygen species, pH shift and inflammatory signals, enabling in situ visualization of pathological signatures of microenvironment and risk evaluation of hemorrhagic transformation. Function‑tailored nanodelivery systems exert multi‑modal protective effects: reactive oxygen species‑responsive polymeric micelles deliver calcium chelators to block calcium‑overload‑initiated injury cascades; nanozymes scavenge reactive oxygen/nitrogen species and revert microglial pro‑inflammatory polarization; biomimetic membrane‑coated nanoparticles accumulate at micro‑thrombosis sites to break thrombo‑inflammatory loops and mitigate no‑reflow phenomenon; ferroptosis‑inhibitor‑loaded nanocarriers eliminate excessive labile iron within perivascular toxic microdomains. During subacute and recovery phases, spatiotemporally controlled release of angiogenic factors by nanocarriers facilitates maturation of newly‑formed microvessels rather than blind vascular sprouting, which helps reconstruct intact blood‑brain barrier and restore microenvironmental homeostasis. Nevertheless, substantial translational bottlenecks still impede clinical transformation of these nanomedicines, including potential biosafety risks caused by in vivo material accumulation, protein‑corona‑induced impairment of targeting capacity, intrinsic blood brain barrier transport obstacles, lack of unified quality‑control criteria for large‑scale manufacture, reliance on high‑end clinical imaging instruments, and prominent interspecies discrepancies between experimental animals and human patients. On the basis of summarizing spatiotemporal pathological characteristics, multi‑level regulatory mechanisms and cutting‑edge microenvironment‑oriented diagnostic and interventional strategies, the present review advocates a conceptual shift from isolated neuronal protection to comprehensive reconstruction of perivascular vascular microenvironment homeostasis. Such perspective provides theoretical foundations for expanding therapeutic time windows and inspires future development of novel therapeutic modalities for ischemic stroke.
ObjectiveTreadmill exercise intervention was evaluated for its effects on addictive behavior, learning and memory, and hippocampal neuroinflammation in methamphetamine (MA)-addicted mice, and transcriptomic screening was performed to identify candidate molecules involved in exercise-mediated attenuation of MA-related neuronal injury.MethodsTwo-month-old male C57BL/6 mice were randomly assigned to four groups: control (C), exercise control (CE), methamphetamine (M), and methamphetamine plus exercise (ME). Mice in the M and ME groups received intraperitoneal injections of MA (1 mg/kg) once daily for 7 consecutive days to establish the addiction model, whereas mice in the C and CE groups received equal volumes of saline. Subsequently, mice in the CE and ME groups underwent treadmill exercise at 12 m/min for 60 min/d for 2 weeks. Conditioned place preference (CPP), the Y-maze, and the Morris water maze (MWM) were used to assess addictive behavior, spatial recognition memory, and spatial learning and memory, respectively. Hippocampal neuronal ultrastructure was examined by transmission electron microscopy (TEM), and microglia-related responses were evaluated by immunofluorescence staining for ionized calcium-binding adapter molecule 1 (Iba-1) in the hippocampal CA1 region. Previously generated and publicly available RNA-seq data from brain tissue of the C, M, and ME groups were reanalyzed, with three biological samples per group. Differentially expressed genes (DEGs) were re-screened using the criteria of P＜0.05 and fold change＞1.5 or ＜0.67, followed by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. NLR family CARD domain containing 5 (Nlrc5) was further validated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and Western blot was used to determine the protein expression of NLRC5, nuclear factor kappa B (NF‑κB), interleukin-1β (IL-1β), postsynaptic density-95 (PSD-95), and synaptophysin.ResultsTreadmill exercise significantly attenuated MA-induced conditioned place preference and improved learning and memory performance in both the Y-maze and MWM tests. Exercise increased exploration time and distance in the novel arm of the Y-maze, shortened escape latency, and increased the number of platform crossings in the MWM. Average swimming speed during the probe trial did not differ significantly among groups, suggesting that the MWM differences were not attributable to obvious differences in swimming performance. TEM revealed that MA exposure induced mitochondrial swelling, disrupted cristae, reduced organelle abundance, and nuclear envelope abnormalities in hippocampal neurons, whereas these ultrastructural changes were alleviated after exercise. Immunofluorescence staining showed that MA increased Iba-1 fluorescence intensity in the hippocampal CA1 region, while treadmill exercise significantly reduced this change. Transcriptomic analysis identified 160 DEGs associated with MA exposure and 58 DEGs associated with exercise intervention, with 9 overlapping DEGs. KEGG enrichment analysis showed that MA-related DEGs were enriched in the NOD-like receptor signaling pathway. Among the overlapping DEGs, Nlrc5, which was downregulated after MA exposure and restored following exercise intervention, was selected as a candidate gene for further validation. RT-qPCR confirmed that treadmill exercise reversed the MA-induced decrease in Nlrc5 mRNA expression. Western blot analysis further showed that treadmill exercise increased NLRC5, PSD-95, and synaptophysin protein expression while reducing NF-κB and IL-1β expression.ConclusionTwo weeks of treadmill exercise attenuated MA-induced conditioned place preference and ameliorated learning and memory impairment, alleviated hippocampal neuroinflammation and neuronal ultrastructural damage, and restored the expression of synapse-related proteins. Transcriptomic screening combined with molecular validation demonstrated that exercise intervention was accompanied by restoration of NLRC5 expression, reduced NF‑κB and IL-1β expression, and increased PSD-95 and synaptophysin expression. These findings suggest that NLRC5 may represent a candidate molecule involved in exercise-mediated amelioration of MA-related neuronal injury. However, the present results mainly demonstrate coordinated changes in NLRC5 expression, inflammatory indicators, and cognitive outcomes rather than a direct causal relationship, and the specific role of NLRC5 requires further functional validation.
