Legumain-Triggered Macrocyclization of Radiofluorinated Tracer for Enhanced PET Imaging.

Enhancing the accumulation and retention of small-molecule probes in tumors is an important way to achieve accurate cancer diagnosis and therapy. Enzyme-stimulated macrocyclization of small molecules possesses great potential for enhanced positron emission tomography (PET) imaging of tumors. Herein, we reported an 18F-labeled radiotracer [18F]AlF-RSM for legumain detection in vivo. The tracer was prepared by a one-step aluminum-fluoride-restrained complexing agent ([18F]AlF-RESCA) method with high radiochemical yield (RCY) (88.35 ± 3.93%) and radiochemical purity (RCP) (>95%). More notably, the tracer can be transformed into a hydrophobic macrocyclic molecule under the joint action of legumain and reductant. Simultaneously, the tracer could target legumain-positive tumors and enhance accumulation and retention in tumors, resulting in the amplification of PET imaging signals. The enhancement of radioactivity enables PET imaging of legumain activity with high specificity. We envision that, by combining this highly efficient 18F-labeled strategy with our intramolecular macrocyclization reaction, a range of radiofluorinated tracers can be designed for tumor PET imaging and early cancer diagnosis in the future.

Lysosome-targeting and legumain-triggered 68Ga-labeled probe for enhanced tumor PET imaging.

Legumain is overexpressed in diverse tumors, serving as a significant tumor biomarker. Our study aimed to develop a new positron emission tomography (PET) probe [68Ga]Ga-NOTA-SF-AANM for imaging the expression level of legumain in vivo. The radio-labeling of [68Ga]Ga-NOTA-SF-AANM was accomplished within 15 min. The probe has good stability in vitro. NOTA-SF-AANM exhibited rapid response to recombinant human legumain enzyme, enabling intramolecular condensation cyclization. Cellular uptake and lysosomal co-localization experiments demonstrated that the probe was able to differentiate specifically between MDA-MB-468 and PC-3 cancer cells with varying degrees of legumain expression. PET imaging displayed a significant and persistent signal (3.59 ± 0.30 %ID/mL at 60 min) in MDA-MB-468 tumors, while PC-3 tumors exhibited lower radioactivity (1.08 ± 0.35 %ID/mL at 60 min), further validating the specific targeting of [68Ga]Ga-NOTA-SF-AANM towards legumain. [68Ga]Ga-NOTA-SF-AANM is a promising tool for precise diagnosis of legumain-related diseases due to its advantages in radio-labeling and accurate monitoring of legumain expression levels.

ß-Galactosidase-Activated and Red Light-Induced RNA Modification Strategy for Prolonged NIR Fluorescence/PET Bimodality Imaging.

Improving the retention of small-molecule-based therapeutic agents in tumors is crucial to achieve precise diagnosis and effective therapy of cancer. Herein, we propose a ß-galactosidase (ß-Gal)-activated and red light-induced RNA modification (GALIRM) strategy for prolonged tumor imaging. A ß-Gal-activatable near-infrared (NIR) fluorescence (FL) and positron emission tomography (PET) bimodal probe 68Ga-NOTA-FCG consists of a triaaza triacetic acid chelator NOTA for 68Ga-labeling, a ß-Gal-activated photosensitizer CyGal, and a singlet oxygen (1O2)-susceptible furan group for RNA modification. Studies have demonstrated that the probe emits an activated NIR FL signal upon cleavage by endogenous ß-Gal overexpressed in the lysosomes, which is combined with the PET imaging signal of 68Ga allowing for highly sensitive imaging of ovarian cancer. Moreover, the capability of 68Ga-NOTA-FCG generating 1O2 under 690 nm illumination could be simultaneously unlocked, which can trigger the covalent cross-linking between furan and nucleotides of cytoplasmic RNAs. The formation of the probe-RNA conjugate can effectively prevent exocytosis and prolong retention of the probe in tumors. We thus believe that this GALIRM strategy may provide entirely new insights into long-term tumor imaging and efficient tumor treatment.

Danlou tablet attenuates ischemic stroke injury and blood‒brain barrier damage by inhibiting ferroptosis.

ETHNOPHARMACOLOGICAL RELEVANCE: Danlou tablet (DLT) is a traditional Chinese medicinal formulation known for replenishing Qi, promoting blood circulation, and resolving stasis. Its pharmacological actions primarily involve anti-inflammatory, antioxidant stress reduction, antiapoptotic, proangiogenic, and improved energy metabolism. DLT has been confirmed to have favorable therapeutic effects on ischemic stroke (IS). However, the underlying mechanism through which DLT affects IS-induced brain injury remains unknown. AIM OF THE STUDY: This study aims to investigate the effects and underlying mechanisms of danlou tablet on ischemic stroke based on network pharmacology and experimental verification. MATERIALS AND METHODS: Using a transient middle cerebral artery occlusion (tMCAO) mouse model, the impact of DLT on the blood‒brain barrier (BBB) and brain injury in mice was assessed. Network pharmacology and bioinformatics analyses were utilized to explore the potential mechanisms of DLT in treating IS. Endothelial cells were cultured to observe the effects of DLT on vascular endothelial cells after oxygen-glucose deprivation/reperfusion, and these findings were validated in the brains of tMCAO mice. RESULTS: DLT alleviated oxidative stress and brain damage in tMCAO mice, mitigating BBB damage. A total of 185 potential targets through which DLT regulates IS were identified, including COX2, a known critical marker of ferroptosis, which identified as a key target. In vitro and in vivo experiments demonstrated that DLT significantly (p < 0.05) improved cell death and vascular barrier damage in IS, reducing intracellular oxidative stress and COX2 protein levels while increasing SLC7A11 and GPX4 protein levels. CONCLUSIONS: This study demonstrated that DLT maintained BBB integrity and alleviated brain injury of tMCAO mice by inhibiting ferroptosis. The study partially unraveled the mechanism through which DLT functioned in treating IS and further clarified the pivotal active components of DLT, thereby providing a theoretical scientific basis for treating IS with DLT.

Dual-Targeting PET Tracers Enable Enzyme-Mediated Self-Assembly for the PET Imaging of Legumain Activity.

Legumain, a lysosomal cysteine protease overexpressed in a variety of tumors, has been considered a promising biomarker for various cancers. Precise detection of legumain activity in the lysosome represents an important strategy for early diagnosis and prognosis of tumors. Small-molecule probes with the property of target-enabled self-assembly hold great potential for molecular imaging. In this study, we reported two dual-targeting radiotracers ([18F]SF-AAN-M and [18F]SF-AAN-HEM) with a property of legumain-mediated self-assembly for positron emission tomography (PET) imaging. Both the radiotracers were synthesized with high labeling yield (>50%) and the radiochemical purity was over 99% via one-step straightforward 18F-labeling. Both tracers were efficiently activated by the reducing agent and legumain to self-assemble into aggregates and showed enhanced retention in legumain-overexpressed MDA-MB-468 cells and tumors, indicating that the introduction of lysosome-targeting morpholine increased the tumor uptake and extended the retention of radiotracers in legumain-overexpressed tumors. In addition, [18F]SF-AAN-HEM with a hydrophilic (histidine-glutamate)3 tag displayed significantly reduced liver uptake with no conspicuous reduction in tumor uptake, affording high signal-to-noise ratios (tumor/liver and tumor/muscle). All of these results suggest that dual-targeting tracer [18F]SF-AAN-HEM could provide a promising tool for in vivo monitoring legumain activity in tumors.

Preparation and Bioevaluation of 18F-Labeled Small-Molecular Radiotracers via Sulfur(VI) Fluoride Exchange Chemistry for Imaging of Programmed Cell Death Protein Ligand 1 Expression in Tumors.

Nowadays, one of the most effective methods of tumor immunotherapy is blocking programmed cell death protein 1/programmed cell death protein ligand 1 (PD-1/PD-L1) immune checkpoints. However, there is still a significant challenge in selecting patients to benefit from immune checkpoint therapies. Positron emission tomography (PET), a noninvasive molecular imaging technique, offers a new approach to accurately detect PD-L1 expression and allows for a better prediction of response to PD-1/PD-L1 target immunotherapy. Here, we designed and synthesized a novel group of aryl fluorosulfate-containing small-molecule compounds (LGSu-1, LGSu-2, LGSu-3, and LGSu-4) based on the phenoxymethyl-biphenyl scaffold. After screening by the time-resolved fluorescence resonance energy transfer (TR-FRET) assay, the most potent compound LGSu-1 (half maximal inhibitory concentration (IC50): 15.53 nM) and the low-affinity compound LGSu-2 (IC50: 189.70 nM) as a control were selected for 18F-radiolabeling by sulfur(VI) fluoride exchange chemistry (SuFEx) to use for PET imaging. [18F]LGSu-1 and [18F]LGSu-2 were prepared by a one-step radiofluorination reaction in over 85% radioconversion and nearly 30% radiochemical yield. In B16-F10 melanoma cell assays, [18F]LGSu-1 (5.00 ± 0.06%AD) showed higher cellular uptake than [18F]LGSu-2 (2.55 ± 0.04%AD), in which cell uptake could be significantly blocked by the nonradioactivity LGSu-1. In vivo experiments, micro-PET imaging of B16-F10 tumor-bearing mice and radiographic autoradiography of tumor sections showed that [18F]LGSu-1 was more effectively accumulated in the tumor due to the higher binding affinity with PD-L1. The above experimental results confirmed the potential of the small-molecule probe LGSu-1 as a targeting PD-L1 imaging tracer in tumor tissues.

Bioinformatics analysis and in vivo validation of ferroptosis-related genes in ischemic stroke.

Ischemic stroke (IS) is a neurological condition associated with high mortality and disability rates. Although the molecular mechanisms underlying IS remain unclear, ferroptosis was shown to play an important role in its pathogenesis. Hence, we applied bioinformatics analysis to identify ferroptosis-related therapeutic targets in IS. IS-related microarray data from the GSE61616 dataset were downloaded from the Gene Expression Omnibus (GEO) database and intersected with the FerrDb database. In total, 33 differentially expressed genes (DEGs) were obtained and subjected to functional enrichment and protein-protein interaction (PPI) network analyses. Four candidate genes enriched in the HIF-1 signaling pathway (HMOX1, STAT3, CYBB, and TLR4) were selected based on the hierarchical clustering of the PPI dataset. We also downloaded the IR-related GSE35338 dataset and GSE58294 dataset from the GEO database to verify the expression levels of these four genes. ROC monofactor analysis demonstrated a good performance of HMOX1, STAT3, CYBB, and TLR4 in the diagnosis of ischemic stroke. Transcriptional levels of the above four genes, and translational level of GPX4, the central regulator of ferroptosis, were verified in a mouse model of middle cerebral artery occlusion (MCAO)-induced IS by qRT-PCR and western blotting. Considering the regulation of the HIF-1 signaling pathway, dexmedetomidine was applied to the MCAO mice. We found that expression of these four genes and GPX4 in MCAO mice were significantly reduced, while dexmedetomidine reversed these changes. In addition, dexmedetomidine significantly reduced MCAO-induced cell death, improved neurobehavioral deficits, and reduced the serum and brain levels of inflammatory factors (TNF-α and IL-6) and oxidative stress mediators (MDA and GSSG). Further, we constructed an mRNA-miRNA-lncRNA network based on the four candidate genes and predicted possible transcription factors. In conclusion, we identified four ferroptosis-related candidate genes in IS and proposed, for the first time, a possible mechanism for dexmedetomidine-mediated inhibition of ferroptosis during IS. These findings may help design novel therapeutic strategies for the treatment of IS.

The 2-(2-benzofuranyl)-2-imidazoline provides neuroprotection against focal cerebral ischemia-reperfusion injury in diabetic rats: Influence of microglia and possible mechanisms of action.

Increased microglial NADPH oxidase (NOX2) production may make an important contribution to the increased incidence and severity of ischemic stroke associated with diabetes. Imidazoline receptors are closely associated with neuroprotection, but the neuroprotective effects of the selective I2-imidazoline receptor ligand 2-(2-benzofuranyl)-2-imidazoline (2BFI) in diabetes has not been established. The effect of 2BFI on microglial NOX2 production was investigated using a co-culture of neurons and microglia, and the effect on cerebral ischemia-reperfusion (IR) injury was determined in diabetic rats. Garcia neurological scores, brain infarct volumes, brain water content, TUNEL staining, blood-brain barrier, and immunofluorescent labeling for microglia were evaluated. Western blots were used to determine gp91phox and Tyr1472 expression. Anti-inflammatory cytokine (IL-10) and inflammatory cytokine secretion was determined using ELISA kits. The brain infarct volumes, TUNEL-positive neurons, expression of microglia, brain water content, blood-brain barrier structure damage, and gp91phox and Tyr1472 expression were increased, the Garcia neurological scores were significantly decreased in the IR group, and 2BFI relieved these alterations. The IL-10 concentration was increased in the IR group; 2BFI significantly improved this increase. The neuron apoptosis and necrosis rates, and production of reactive oxygen species (ROS) and inflammatory cytokines, including IL-6, IL-8, TNF-α, and 8-iso-PGF2α, were significantly increased by high glucose stimulation combined with oxygen-glucose deprivation treatment, which were inhibited by 2BFI. The 2BFI ameliorated cerebral ischemia-reperfusion injury in diabetes and decreased neuron death in an in vitro model. The mechanism underlying these findings may be related to the decreased production of inflammatory factors and reactive oxygen species from microglia.

Gp91phox (NOX2) in Activated Microglia Exacerbates Neuronal Damage Induced by Oxygen Glucose Deprivation and Hyperglycemia in an in Vitro Model.

BACKGROUND/AIMS: Peri-operative cerebral ischemia reperfusion injury is one of the most serious peri-operative complications that can be aggravated in patients with diabetes. A previous study showed that microglia NOX2 (a NADPH oxidase enzyme) may play an important role in this process. Here, we investigated whether increased microglial derived gp91phox, also known as NOX2, reduced oxygen glucose deprivation (OGD) after induction of hyperglycemia (HG). METHODS: A rat neuronal-microglial in vitro co-culture model was used to determine the effects of gp91phox knockdown on OGD after HG using six treatment groups: A rat microglia and neuron co-culture model was established and divided into the following six groups: high glucose + scrambled siRNA transfection (HG, n = 5); HG + gp91phoxsiRNA transfection (HG-gp91siRNA, n = 5); oxygen glucose deprivation + scrambled siRNA transfection (OGD, n = 5); OGD + gp91phoxsiRNA transfection (OGD-gp91siRNA, n = 5); HG + OGD + scrambled siRNA transfection (HG-OGD, n = 5); and HG + OGD + gp91phoxsiRNA transfection (HG-OGD-gp91siRNA, n = 5). The neuronal survival rate was measured by the MTT assay, while western blotting was used to determine gp91phox expression. Microglial derived ROS and neuronal apoptosis rates were analyzed by flow cytometry. Finally, the secretion of cytokines, including IL-6, IL-8, TNF-α, and 8-iso-PGF2α was determined using an ELISA kit. RESULTS: Neuronal survival rates were significantly decreased by HG and OGD, while knockdown of gp91phox reversed these rates. ROS production and cytokine secretion were also significantly increased by HG and OGD but were significantly inhibited by knockdown of gp91phoxsiRNA. CONCLUSION: Knockdown of gp91phoxsiRNA significantly reduced oxidative stress and the inflammatory response, and alleviated neuronal damage after HG and OGD treatment in a rat neuronal-microglial co-culture model.

Association between single nucleotide polymorphisms in the OPRM1 gene and intraoperative remifentanil consumption in northern Chinese women.

BACKGROUND: Recent studies have suggested that some single nucleotide polymorphisms (SNPs) in the human µ-opioid receptor gene (OPRM1) affect the postoperative analgesic efficacy of opioids and their side effects. In this study, we assessed the association between SNPs in the OPRM1 gene and intraoperative remifentanil consumption as well as perioperative side effects during gynecological hysteroscopic surgery in women from Northern China. METHODS: We analyzed 178 women undergoing gynecological hysteroscopic surgery. SNP genotyping was performed using the SNaPshot method. The state anxiety index (SAI) and pressure pain threshold (PPT) of all patients were assessed preoperatively. Monitored anesthesia care was maintained by the intravenous infusion of remifentanil. Intraoperative remifentanil usage and perioperative side effects were recorded. Statistical analyses were performed using SPSS software. RESULTS: Patients carrying one or two copies of the minor allele (G allele) of rs558025 required significantly more intraoperative remifentanil than patients without the minor allele (p = 0.001, corrected p = 0.006). There were no significant associations between the six SNPs and various clinical characteristics. No significant associations between the six SNPs and PPT or SAI were found in our study. CONCLUSIONS: SNP rs558025 in the OPRM1 gene was associated with intraoperative remifentanil consumption during gynecological hysteroscopic surgery in our subjects.

Associations between single-nucleotide polymorphisms and epidural ropivacaine consumption in patients undergoing breast cancer surgery.

Up to date, few published studies indicated the associations between genetic polymorphisms and epidural local anesthetics consumption. In this study, we investigated the associations between seven single-nucleotide polymorphisms (SNPs) and epidural ropivacaine consumption during breast cancer surgery in women from northeastern China. These seven SNPs (rs3803662 and rs12443621 in TNCR9, rs889312 in MAP3K1, rs3817198 in LSP1, rs13387042 at 2q35, rs13281615 at 8q24, and rs2046210 at 6q25.1) were identified by recent genome-wide association studies associated with tumor susceptibility. A total of 418 breast cancer women received thoracic epidural anesthesia with ropivacaine for elective mastectomy with axillary clearance. Their blood samples were genotyped for the seven SNPs using the SNaPshot method. For SNP rs13281615, the subjects with genotype AG and GG consumed a greater amount of the total epidural ropivacaine and the mean ropivacaine dose than the subjects with genotype AA (p=0.047 and p=0.003, respectively). Furthermore, no statistical differences were found in the total dose of ropivacaine, the mean consumption of ropivacaine, the onset of ropivacaine, or the initial dose of lidocaine among the three genotypic groups for the other six SNPs studied. Our study indicated that SNP rs13281615 at 8q24 was associated with the consumption of epidural ropivacaine during breast cancer surgery in northeastern Chinese women. It might provide new insights into the mechanisms of ropivacaine action and metabolism and facilitate the development of personalized medicine.

Propofol improved neurobehavioral outcome of cerebral ischemia-reperfusion rats by regulating Bcl-2 and Bax expression.

Propofol is an intravenous anesthetic with neuroprotective effects against cerebral ischemia-reperfusion (I/R) injury. Few studies regarding the neuroprotective and neurobehavioral effects of propofol have been conducted, and the underlying mechanisms are still unclear. Because I/R may result in neuronal apoptosis, the apoptosis regulatory genes B-cell leukemia-2 (Bcl-2) and Bcl-2-associated X protein (Bax) may be involved in the neuroprotective process. In this study, 120 Wistar rats were randomly divided into three groups (sham, I/R-induced, and propofol-treated). Cerebral ischemia was induced by clamping the bilateral common carotid arteries for 10min. Propofol (1.0mg/kg/min) was administered intravenously for 1h before the induction of ischemia. Neuronal damage was evaluated by neurobehavioral scores and histological examination of the brain sections at the level of the dorsal hippocampus at 6h, 24h, 48h, 72h, 4days, 5days, 6days, and 7days after I/R. The apoptotic rate of hippocampal neurons was detected by flow cytometry. The expression of Bcl-2 and Bax was evaluated using immunohistochemical and Western blot methods. The results of this study showed that neurobehavioral scores were higher in propofol-treated rats compared with I/R-induced rats with no propofol treatment. Moreover, the hippocampal expression of Bcl-2 was significantly higher, while the expression of Bax was significantly lower in propofol-treated rats compared with I/R-induced rats at 24h after ischemia. Hence, this study suggests that the neuroprotective effects of propofol against neuronal apoptosis may be a consequence of the regulation of Bcl-2 and Bax.

Propofol inhibited the delayed rectifier potassium current (I(k)) via activation of protein kinase C epsilon in rat parietal cortical neurons.

Propofol has been shown to exert neuroprotective effects. Delayed rectifier potassium current (I(K)) was reported to be closely related to neuronal damage. This study was designed to test the effects of propofol on I(K) in rat parietal cortical neurons and the involvement of PKC in this activity. Whole-cell patch-clamp recordings were performed in rat parietal cortical neurons. The amplitudes of I(K) were recorded before and after the addition of different concentrations of propofol. Propofol concentration-dependently inhibited I(K) with an IC50 value of 36.3±2.7 µM. Moreover, propofol caused a downward shift of the I-V curve of I(K) in a concentration dependent manner. The kinetics of I(K) was altered by propofol, with decreased activation and delayed recovery of I(K). Pretreatment with calphostin-C (a non-selective inhibitor of PKC) or PKC epsilon translocation inhibitor peptide (PKC epsilon inhibitor) abrogated the inhibition of I(K) by propofol. In conclusion, propofol inhibited I(K) via the activation of PKC epsilon in rat cerebral parietal cortical neurons.