The laminin receptor is a receptor for Micropterus salmoides rhabdovirus

Micropterus salmoides rhabdovirus (MSRV) is an important pathogen of largemouth bass. Despite extensive research, the functional receptors of MSRV remained unknown. This study identified the host protein, laminin receptor (LamR), as a cellular receptor facilitating MSRV entry into host cells. Our results demonstrated that LamR directly interacts with MSRV G protein, playing a pivotal role in the attachment and internalization processes of MSRV. Knockdown of LamR with siRNA, blocking cells with LamR antibody, or incubating MSRV virions with soluble LamR protein significantly reduced MSRV entry. Notably, we found that LamR mediated MSRV entry via clathrin-mediated endocytosis. Additionally, our findings revealed that MSRV G and LamR were internalized into cells and co-localized in the early and late endosomes. These findings highlight the significance of LamR as a cellular receptor facilitating MSRV binding and entry into target cells through interaction with the MSRV G protein.

IMPORTANCE

Despite the serious epidemic caused by Micropterus salmoides rhabdovirus (MSRV) in largemouth bass, the precise mechanism by which it invades host cells remains unclear. Here, we determined that laminin receptor (LamR) is a novel target of MSRV, that interacts with its G protein and is involved in viral attachment and internalization, transporting with MSRV together in early and late endosomes. This is the first report demonstrating that LamR is a cellular receptor in the MSRV life cycle, thus contributing new insights into host-pathogen interactions.

Shape Dependent Therapeutic Potential of Nanoparticulate System: Advance Approach for Drug Delivery

Drug delivery systems rely heavily on nanoparticles because they provide a targeted and monitored release of pharmaceuticals that maximize therapeutic efficacy and minimize side effects. To maximize drug internalization, this review focuses on comprehending the interactions between biological systems and nanoparticles. The way that nanoparticles behave during cellular uptake, distribution, and retention in the body is determined by their shape. Different forms, such as mesoporous silica nanoparticles, micelles, and nanorods, each have special properties that influence how well drugs are delivered to cells and internalized. To achieve the desired particle morphology, shape-controlled nanoparticle synthesis strategies take into account variables like pH, temperatures, and reaction time. Top-down techniques entail dissolving bulk materials to produce nanoparticles, whereas bottom-up techniques enable nanostructures to self-assemble. Comprehending the interactions at the bio-nano interface is essential to surmounting biological barriers and enhancing the therapeutic efficacy of nanotechnology in drug delivery systems. In general, drug internalization and distribution are greatly influenced by the shape of nanoparticles, which presents an opportunity for tailored and efficient treatment plans in a range of medical applications.

A Quantitative Method to Distinguish Cytosolic from Endosome-Trapped Cell-Penetrating Peptides

Cell-penetrating peptides are known to penetrate cells through endocytosis and translocation. The two pathways are hardly distinguished in current cell assays. We developed a reliable, simple and robust method to distinguish and quantify independently the two routes. The assay requires (DABCYL) 4-(dimethylaminoazo)benzene-4-carboxylic acid- and (CF) carboxyfluorescein-labeled peptides. When the labeled peptide is intact, the fluorescence signal is weak thanks to the dark quenching property of DABCYL. A 10-fold higher fluorescence signal is measured when the labeled peptide is degraded. By referring to a standard fluorescent curve according to the concentration of the hydrolyzed peptide, we have access to the internalized peptide quantity. Therefore, cell lysis after internalization permits to determine the total quantity of intracellular peptide. The molecular state of the internalized peptide (intact or degraded), depends on its location in cells (cytosol vs endo-lysosomes), and can be blocked by boiling cells. This boiling step results indeed in denaturation and inhibition of the cellular enzymes. The advantage of this method is the possibility to quantify translocation at 37 °C and to compare it to the 4 °C condition, where all endocytosis processes are inhibited. We found that ranking of the translocation efficacy is DABCYL-R6-(ϵCF)K≫DABCYL-R4-(ϵCF)K≥CF-R9.

Altered desensitization and internalization patterns of rodent versus human glucose-dependent insulinotropic polypeptide (GIP) receptors. An important drug discovery challenge

BACKGROUND AND PURPOSE

The gut hormone glucose-dependent insulinotropic polypeptide (GIP) signals via the GIP receptor (GIPR), resulting in postprandial potentiation of glucose-stimulated insulin secretion. The translation of results from rodent studies to human studies has been challenged by the unexpected effects of GIPR-targeting compounds. We, therefore, investigated the variation between species, focusing on GIPR desensitization and the role of the receptor C-terminus.

EXPERIMENTAL APPROACH

The GIPR from humans, mice, rats, pigs, dogs and cats was studied in vitro for cognate ligand affinity, G protein activation (cAMP accumulation), recruitment of beta-arrestin and internalization. Variants of the mouse, rat and human GIPRs with swapped C-terminal tails were studied in parallel.

KEY RESULTS

The human GIPR is more prone to internalization than rodent GIPRs. Despite similar agonist affinities and potencies for Gαs activation, especially, the mouse GIPR shows reduced receptor desensitization, internalization and beta-arrestin recruitment. Using an enzyme-stabilized, long-acting GIP analogue, the species differences were even more pronounced. 'Tail-swapped' human, rat and mouse GIPRs were all fully functional in their Gαs coupling, and the mouse GIPR regained internalization and beta-arrestin 2 recruitment properties with the human tail. The human GIPR lost the ability to recruit beta-arrestin 2 when its own C-terminus was replaced by the rat or mouse tail.

CONCLUSIONS AND IMPLICATIONS

Desensitization of the human GIPR is dependent on the C-terminal tail. The species-dependent functionality of the C-terminal tail and the different species-dependent internalization patterns, especially between human and mouse GIPRs, are important factors influencing the preclinical evaluation of GIPR-targeting therapeutic compounds.

Modification of the Antibiotic, Colistin, with Dextrin Causes Enhanced Cytotoxicity and Triggers Apoptosis in Myeloid Leukemia

Introduction

Acute myeloid leukemia (AML) remains difficult to treat due to its heterogeneity in molecular landscape, epigenetics and cell signaling alterations. Precision medicine is a major goal in AML therapy towards developing agents that can be used to treat patients with different 'subtypes' in combination with current chemotherapies. We have previously developed dextrin-colistin conjugates to combat the rise in multi-drug resistant bacterial infections and overcome dose-limiting nephrotoxicity. Recent evidence of colistin's anticancer activity, mediated through inhibition of intracellular lysine-specific histone demethylase 1 (LSD1/KDM1A), suggests that dextrin-colistin conjugates could be used to treat cancer cells, including AML. This study aimed to evaluate whether dextrin conjugation (which reduces in vivo toxicity and prolongs plasma half-life) could enhance colistin's cytotoxic effects in myeloid leukemia cell lines and compare the intracellular uptake and localization of the free and conjugated antibiotic.

Results

Our results identified a conjugate (containing 8000 g/mol dextrin with 1 mol% succinoylation) that caused significantly increased toxicity in myeloid leukemia cells, compared to free colistin. Dextrin conjugation altered the mechanism of cell death by colistin, from necrosis to caspase 3/7-dependent apoptosis. In contrast, conjugation via a reversible ester linker, instead of an amide, had no effect on the mechanism of the colistin-induced cell death. Live cell confocal microscopy of fluorescently labelled compounds showed both free and dextrin-conjugated colistins were endocytosed and co-localized in lysosomes, and increasing the degree of modification by succinoylation of dextrin significantly reduced colistin internalization.

Discussion

Whilst clinical translation of dextrin-colistin conjugates for the treatment of AML is unlikely due to the potential to promote antimicrobial resistance (AMR) and the relatively high colistin concentrations required for anticancer activity, the ability to potentiate the effectiveness of an anticancer drug by polymer conjugation, while reducing side effects and improving biodistribution of the drug, is very attractive, and this approach warrants further investigation.

Synergistic effects of quercetin-loaded CoFe2O4@Liposomes regulate DNA damage and apoptosis in MCF-7 cancer cells: based on biophysical magnetic hyperthermia

INTRODUCTION

Breast cancer (BC) is the most common malignancy in women globally. Significant progress has been made in developing structural nanoparticles (NPs) and formulations for targeted smart drug delivery (SDD) of pharmaceuticals, improving the precision of tumor cell targeting in therapy.

SIGNIFICANCE

Magnetic hyperthermia (MHT) treatment using magneto-liposomes (MLs) has emerged as a promising adjuvant cancer therapy.

METHODS

CoFe2O4 magnetic NPs (MNPs) were conjugated with nanoliposomes to form MLs, and the anticancer drug quercetin (Que) was loaded into MLs, forming Que-MLs composites for antitumor approach. The aim was to prepare Que-MLs for DD systems (DDS) under an alternating magnetic field (AMF), termed chemotherapy/hyperthermia (chemo-HT) techniques. The encapsulation efficiency (EE), drug loading capacity (DL), and drug release (DR) of Que and Que-MLs were evaluated.

RESULTS

The results confirmed successful Que-loading on the surface of MLs, with an average diameter of 38 nm and efficient encapsulation into MLs (69%). In vitro, experimental results on MCF-7 breast cells using MHT showed high cytotoxic effects of novel Que-MLs on MCF-7 cells. Various analyses, including cytotoxicity, apoptosis, cell migration, western blotting, fluorescence imaging, and cell membrane internalization, were conducted. The Acridine Orange-ethidium bromide double fluorescence test identified 35% early and 55% late apoptosis resulting from Que-MLs under the chemo-HT group. TEM results indicated MCF-7 cell membrane internalization and digestion of Que-MLs, suggesting the presence of early endosome-like vesicles on the cytoplasmic periphery.

CONCLUSIONS

Que-MLs exhibited multi-modal chemo-HT effects, displaying high toxicity against MCF-7 BC cells and showing promise as a potent cytotoxic agent for BC chemotherapy.

Fullerene C60 Conjugate with Folic Acid and Polyvinylpyrrolidone for Targeted Delivery to Tumor Cells

The use of targeted drug delivery systems, including those based on selective absorption by certain receptors on the surface of the target cell, can lead to a decrease in the minimum effective dose and the accompanying toxicity of the drug, as well as an increase in therapeutic efficacy. A fullerene C60 conjugate (FA-PVP-C60) with polyvinylpyrrolidone (PVP) as a biocompatible spacer and folic acid (FA) as a targeting ligand for tumor cells with increased expression of folate receptors (FR) was obtained. Using 13C NMR spectroscopy, FT-IR, UV-Vis spectrometry, fluorometry and thermal analysis, the formation of the conjugate was confirmed and the nature of the binding of its components was established. The average particle sizes of the conjugate in aqueous solutions and cell culture medium were determined using dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA). The FA-PVP-C60 showed antiradical activity against •DPPH, •OH and O2•-, but at the same time, it was shown to generate 1O2. It was found that the conjugate in the studied concentration range (up to 200 μg/mL) is non-toxic in vitro and does not affect the cell cycle. To confirm the ability of the conjugate to selectively accumulate through folate-mediated endocytosis, its uptake into cells was analyzed by flow cytometry and confocal microscopy. It was shown that the conjugate is less absorbed by A549 cells with low FR expression than by HeLa, which has a high level of expression of this receptor.

LRP1 is the cell-surface endocytosis receptor for vaspin in adipocytes

Vaspin is a serine protease inhibitor that protects against adipose tissue inflammation and insulin resistance, two key drivers of adipocyte dysfunction and metabolic disorders in obesity. Inhibition of target proteases such as KLK7 has been shown to reduce adipose tissue inflammation in obesity, while vaspin binding to cell surface GRP78 has been linked to reduced obesity-induced ER stress and insulin resistance in the liver. However, the molecular mechanisms by which vaspin directly affects cellular processes in adipocytes remain unknown. Using fluorescently labeled vaspin, we found that vaspin is rapidly internalized by mouse and human adipocytes, but less efficiently by endothelial, kidney, liver, and neuronal cells. Internalization occurs by active, clathrin-mediated endocytosis, which is dependent on vaspin binding to the LRP1 receptor, rather than GRP78 as previously thought. This was demonstrated by competition experiments and RNAi-mediated knock-down in adipocytes and by rescuing vaspin internalization in LRP1-deficient Pea13 cells after transfection with a functional LRP1 minireceptor. Vaspin internalization is further increased in mature adipocytes after insulin-stimulated translocation of LRP1. Although vaspin has nanomolar affinity for LRP1 clusters II-IV, binding to cell surface heparan sulfates is required for efficient LRP1-mediated internalization. Native, but not cleaved vaspin, and also vaspin polymers are efficiently endocytosed, and ultimately targeted for lysosomal degradation. Our study provides mechanistic insight into the uptake and degradation of vaspin in adipocytes, thereby broadening our understanding of its functional repertoire. We hypothesize the vaspin-LRP1 axis to be an important mediator of vaspin effects not only in adipose tissue but also in other LRP1-expressing cells.

The anticancer activity of bovine lactoferrin is reduced by deglycosylation and it follows a different pathway in cervix and colon cancer cells

Bovine lactoferrin (bLF) is a glycosylated protein with purported beneficial properties. The aim of this work was to determine the role of bLF glycosylation in the adhesion, internalization, and growth inhibition of cancer cells. The viability of cervix (HeLa) and colon (Caco-2) cancer cells (MTT assay and epifluorescence microscopy) was inhibited by bLF, while deglycosylated bLF (bLFdeg) had no effect. Adhesion to cell surfaces was quantified by immunofluorescence assay and showed that bLF was able to bind more efficiently to both cell lines than bLFdeg. Microscopic observations indicated that bLF glycosylation favored bLF binding to epithelial cells and that it was endocytosed through caveolin-1-mediated internalization. In addition, the mechanism of action of bLF on cancer cell proliferation was investigated by determining the amount of phosphorylated intermediates of signaling pathways such as epidermal growth factor receptor (EGFR), extracellular signal-regulated kinase (ERK) and protein kinase B (known as Akt). Chemoluminescence immunoassay of phosphorylated intermediates showed that bLF inhibited Akt phosphorylation, consistent with its growth inhibiting activity. This assay also indicated that the bLF receptor/signaling pathways may be different in the two cell lines, Caco-2 and HeLa. This work confirmed the effect of glycosylated bLF in inhibiting cancer cell growth and that glycosylation is required for optimal surface adhesion, internalization, and inhibition of the ERK/Akt pathway of cell proliferation through glycosylated cell surface receptors.

A Conserved Intramolecular Ion-Pair Plays a Critical but Divergent Role in Regulation of Dimerization and Transport Function among the Monoamine Transporters

The monoamine transporters, including the serotonin transporter (SERT), dopamine transporter (DAT), and norepinephrine transporter (NET), are the therapeutic targets for the treatment of many neuropsychiatric disorders. Despite significant progress in characterizing the structures and transport mechanisms of these transporters, the regulation of their transport functions through dimerization or oligomerization remains to be understood. In the present study, we identified a conserved intramolecular ion-pair at the third extracellular loop (EL3) connecting TM5 and TM6 that plays a critical but divergent role in the modulation of dimerization and transport functions among the monoamine transporters. The disruption of the ion-pair interactions by mutations induced a significant spontaneous cross-linking of a cysteine mutant of SERT and an increase in cell surface expression but with an impaired specific transport activity. On the other hand, similar mutations of the corresponding ion-pair residues in both DAT and NET resulted in an opposite effect on their oxidation-induced dimerization, cell surface expression, and transport function. Reversible biotinylation experiments indicated that the ion-pair mutations slowed down the internalization of SERT but stimulated the internalization of DAT. In addition, cysteine accessibility measurements for monitoring SERT conformational changes indicated that substitution of the ion-pair residues resulted in profound effects on the rate constants for cysteine modification in both the extracellular and cytoplasmatic substrate permeation pathways. Furthermore, molecular dynamics simulations showed that the ion-pair mutations increased the interfacial interactions in a SERT dimer but decreased it in a DAT dimer. Taken together, we propose that the transport function is modulated by the equilibrium between monomers and dimers on the cell surface, which is regulated by a potential compensatory mechanism but with different molecular solutions among the monoamine transporters. The present study provided new insights into the structural elements regulating the transport function of the monoamine transporters through their dimerization.

The phosphatidylinositol-5' phosphatase synaptojanin1 limits integrin-mediated invasion of Staphylococcus aureus

The gram-positive bacterium Staphylococcus aureus can invade non-professional phagocytic cells by associating with the plasma protein fibronectin to exploit host cell integrins. Integrin-mediated internalization of these pathogens is facilitated by the local production of phosphatidylinositol-4,5-bisphosphate (PI-4,5-P2) via an integrin-associated isoform of phosphatidylinositol-5' kinase. In this study, we addressed the role of PI-4,5-P2-directed phosphatases on internalization of S. aureus. ShRNA-mediated knockdown of individual phosphoinositide 5-phosphatases revealed that synaptojanin1 (SYNJ1) is counteracting invasion of S. aureus into mammalian cells. Indeed, shRNA-mediated depletion as well as genetic deletion of synaptojanin1 via CRISPR/Cas9 resulted in a gain-of-function phenotype with regard to integrin-mediated uptake. Surprisingly, the surface level of integrins was slightly downregulated in Synj1-KO cells. Nevertheless, these cells showed enhanced local accumulation of PI-4,5-P2 and exhibited increased internalization of S. aureus. While the phosphorylation level of the integrin-associated protein tyrosine kinase FAK was unaltered, the integrin-binding and -activating protein talin was enriched in the vicinity of S. aureus in synaptojanin1 knockout cells. Scanning electron microscopy revealed enlarged membrane invaginations in the absence of synaptojanin1 explaining the increased capability of these cells to internalize integrin-bound microorganisms. Importantly, the enhanced uptake by Synj1-KO cells and the exaggerated morphological features were rescued by the re-expression of the wild-type enzyme but not phosphatase inactive mutants. Accordingly, synaptojanin1 activity limits integrin-mediated invasion of S. aureus, corroborating the important role of PI-4,5-P2 during this process.IMPORTANCEStaphylococcus aureus, an important bacterial pathogen, can invade non-professional phagocytes by capturing host fibronectin and engaging integrin α5β1. Understanding how S. aureus exploits this cell adhesion receptor for efficient cell entry can also shed light on the physiological regulation of integrins by endocytosis. Previous studies have found that a specific membrane lipid, phosphatidylinositol-4,5-bisphosphate (PIP2), supports the internalization process. Here, we extend these findings and report that the local levels of PIP2 are controlled by the activity of the PIP2-directed lipid phosphatase Synaptojanin1. By dephosphorylating PIP2 at bacteria-host cell attachment sites, Synaptojanin1 counteracts the integrin-mediated uptake of the microorganisms. Therefore, our study not only generates new insight into subversion of cellular receptors by pathogenic bacteria but also highlights the role of host cell proteins acting as restriction factors for bacterial invasion at the plasma membrane.

Lack of Laminar Shear Stress Facilitates the Endothelial Uptake of Very Small Superparamagnetic Iron Oxide Nanoparticles by Modulating the Endothelial Surface Layer

Purpose

To study whether the absence of laminar shear stress (LSS) enables the uptake of very small superparamagnetic iron oxide nanoparticles (VSOP) in endothelial cells by altering the composition, size, and barrier function of the endothelial surface layer (ESL).

Methods and Results

A quantitative particle exclusion assay with living human umbilical endothelial cells using spinning disc confocal microscopy revealed that the dimension of the ESL was reduced in cells cultivated in the absence of LSS. By combining gene expression analysis, flow cytometry, high pressure freezing/freeze substitution immuno-transmission electron microscopy, and confocal laser scanning microscopy, we investigated changes in ESL composition. We found that increased expression of the hyaluronan receptor CD44 by absence of shear stress did not affect the uptake rate of VSOPs. We identified collagen as a previously neglected component of ESL that contributes to its barrier function. Experiments with inhibitor halofuginone and small interfering RNA (siRNA) demonstrated that suppression of collagen expression facilitates VSOP uptake in endothelial cells grown under LSS.

Conclusion

The absence of laminar shear stress disturbs the barrier function of the ESL, facilitating membrane accessibility and endocytic uptake of VSOP. Collagen, a previously neglected component of ESL, contributes to its barrier function.

Targeting cell surface glucose-regulated protein 94 in gastric cancer with an anti-GRP94 human monoclonal antibody

Gastric cancer (GC), a leading cause of cancer-related mortality, remains a significant challenge despite recent therapeutic advancements. In this study, we explore the potential of targeting cell surface glucose-regulated protein 94 (GRP94) with antibodies as a novel therapeutic approach for GC. Our comprehensive analysis of GRP94 expression across various cancer types, with a specific focus on GC, revealed a substantial overexpression of GRP94, highlighting its potential as a promising target. Through in vitro and in vivo efficacy assessments, as well as toxicological analyses, we found that K101.1, a fully human monoclonal antibody designed to specifically target cell surface GRP94, effectively inhibits GC growth and angiogenesis without causing in vivo toxicity. Furthermore, our findings indicate that K101.1 promotes the internalization and concurrent downregulation of cell surface GRP94 on GC cells. In conclusion, our study suggests that cell surface GRP94 may be a potential therapeutic target in GC, and that antibody-based targeting of cell surface GRP94 may be an effective strategy for inhibiting GRP94-mediated GC growth and angiogenesis. [BMB Reports 2024; 57(4): 188-193].

Current Utility of Transgastric Percutaneous Drainage for the Management of Pancreatitis-Related Retrogastric Walled-Off Necrotic Collections: A Prospective Observational Study

Introduction Pancreatic fluid collection (PFC) is one of the most frequent complications associated with acute pancreatitis. The route of drainage is guided by the size and site of collection. The present study aims to assess the clinical and technical success of transgastric percutaneous drainage (PCD) for managing retrogastric walled-off pancreatic necrosis (WOPN). Materials and methods A total of 44 patients with acute pancreatitis diagnosed with WOPN who underwent transgastric PCD with ultrasound or CT guidance as part of standard clinical management were included in the study. Patients were observed for improvement in clinical parameters, and treatment outcomes were noted in terms of technical success, clinical success, adverse events, need for additional procedures, hospital stay, and duration of placement of all drains. Data for the internalization of transgastric PCD was also observed in the study. Results Technical success during the drain placement was observed in 93% (n=41) of patients.Internalization of the transgastric drain was attempted in 12 patients and successful in 11 (91%). The median duration of hospital stay from the time of placement of the first PCD until discharge and the median duration of all PCDs placed were higher in patients where the transgastric drain was not internalized as compared to patients where the transgastric drain was internalized. Conclusion In WOPN, transgastric drain placement and successful internalization in any form help in the early resolution of peripancreatic and abdominal collections. It also reduces the time to percutaneous catheter removal, which in turn reduces the morbidity and decreases the need for additional interventions or surgery.

The "Young Athlete Body Project"-A pilot study evaluating the acceptability of and results from an eating disorder prevention program for adolescent athletes

BACKGROUND

The high frequency of eating disorders (EDs) in sports speaks of a need for early-stage preventive measures.

OBJECTIVES

This study evaluated the acceptability of an age, sex, and sports adapted version of the "Body Project" and changes in mental health symptoms.

METHODS

This noncontrolled pilot study included a class of athletes from 18 sports (N = 73, 13-14 years) at a sport-specialized junior high school in six small-group workshops. We interviewed 34 athletes on program acceptability, and all athletes responded to questionnaires at pretest, posttest, and 6-month follow-up including the Body Appreciation Scale 2-Children, Social Attitudes towards Appearance Questionnaire-4 revised, Eating Disorder Examination Questionnaire Short form-12 modified, and questions about body appearance pressure (BAP).

RESULTS

Athletes found the program acceptable and beneficial, but some missed physically oriented activities or did not identify with the focus, particularly boys. There were acceptable levels in mental health constructs before the workshops. There were temporary changes in the percentage of boys experiencing "BAP in society" by -14.8% points (95% CI: -.6 to .0, p = .04), % in total group experiencing "BAP at school" by +11% points (95% CI: .0-.2, p = .05), thinness idealization by girls (g = .6, p = .002) and total group (g = .4, p = .006), and muscularity idealization by boys (g = .3, p = .05) and total group (g = .23, p = .04).

DISCUSSION

Athletes experienced benefits from the Young Athlete Body Project. Seeing stabilization in outcomes may mean a dampening of the otherwise expected worsening in body appreciation and ED symptoms over time.

PUBLIC SIGNIFICANCE

Adolescent athletes are at risk for developing EDs. Due to lack of prevention programs for this group, we adapted and evaluated a well-documented effective program, the Body Project, to fit male and female athletes <15 years. The athletes accepted the program and experienced participation benefits, with stronger acceptance among girls. Our promising findings encourage larger scaled randomized controlled trials to further evaluate a refined version this program among very young athletes.

Emerging Issues and Initial Insights into Bacterial Biofilms: From Orthopedic Infection to Metabolomics

Bacterial biofilms, enigmatic communities of microorganisms enclosed in an extracellular matrix, still represent an open challenge in many clinical contexts, including orthopedics, where biofilm-associated bone and joint infections remain the main cause of implant failure. This study explores the scenario of biofilm infections, with a focus on those related to orthopedic implants, highlighting recently emerged substantial aspects of the pathogenesis and their potential repercussions on the clinic, as well as the progress and gaps that still exist in the diagnostics and management of these infections. The classic mechanisms through which biofilms form and the more recently proposed new ones are depicted. The ways in which bacteria hide, become impenetrable to antibiotics, and evade the immune defenses, creating reservoirs of bacteria difficult to detect and reach, are delineated, such as bacterial dormancy within biofilms, entry into host cells, and penetration into bone canaliculi. New findings on biofilm formation with host components are presented. The article also delves into the emerging and critical concept of immunometabolism, a key function of immune cells that biofilm interferes with. The growing potential of biofilm metabolomics in the diagnosis and therapy of biofilm infections is highlighted, referring to the latest research.

Heparan sulfate promotes TRAIL-induced tumor cell apoptosis

TRAIL (TNF-related apoptosis-inducing ligand) is a potent inducer of tumor cell apoptosis through TRAIL receptors. While it has been previously pursued as a potential anti-tumor therapy, the enthusiasm subsided due to unsuccessful clinical trials and the fact that many tumors are resistant to TRAIL. In this report, we identified heparan sulfate (HS) as an important regulator of TRAIL-induced apoptosis. TRAIL binds HS with high affinity (KD = 73 nM) and HS induces TRAIL to form higher-order oligomers. The HS-binding site of TRAIL is located at the N-terminus of soluble TRAIL, which includes three basic residues. Binding to cell surface HS plays an essential role in promoting the apoptotic activity of TRAIL in both breast cancer and myeloma cells, and this promoting effect can be blocked by heparin, which is commonly administered to cancer patients. We also quantified HS content in several lines of myeloma cells and found that the cell line showing the most resistance to TRAIL has the least expression of HS, which suggests that HS expression in tumor cells could play a role in regulating sensitivity towards TRAIL. We also discovered that death receptor 5 (DR5), TRAIL, and HS can form a ternary complex and that cell surface HS plays an active role in promoting TRAIL-induced cellular internalization of DR5. Combined, our study suggests that TRAIL-HS interactions could play multiple roles in regulating the apoptotic potency of TRAIL and might be an important point of consideration when designing future TRAIL-based anti-tumor therapy.

Antibody-Drug Conjugates: The Dynamic Evolution from Conventional to Next-Generation Constructs

Introduced almost two decades ago, ADCs have marked a breakthrough in the targeted therapy era, providing clinical benefits to many cancer patients. While the inherent complexity of this class of drugs has challenged their development and broad application, the experience gained from years of trials and errors and recent advances in construct design and delivery have led to an increased number of ADCs approved or in late clinical development in only five years. Target and payload diversification, along with novel conjugation and linker technologies, are at the forefront of next-generation ADC development, renewing hopes to broaden the scope of these targeted drugs to difficult-to-treat cancers and beyond. This review highlights recent trends in the ADC field, focusing on construct design and mechanism of action and their implications on ADCs' therapeutic profile. The evolution from conventional to innovative ADC formats will be illustrated, along with some of the current hurdles, including toxicity and drug resistance. Future directions to improve the design of next-generation ADCs will also be presented.

Cellular Uptake of Engineered Extracellular Vesicles: Biomechanisms, Engineered Strategies, and Disease Treatment

Extracellular vesicles (EVs), lipid-enclosed nanosized membrane vesicles, are regarded as new vehicles and therapeutic agents in intercellular communication. During internal circulation, if EVs are not effectively taken up by recipient cells, they will be cleared as "cellular waste" and unable to deliver therapeutic components. It can be seen that cells uptake EVs are the prerequisite premise for sharing intercellular biological information. However, natural EVs have a low rate of absorption by their recipient cells, off-target delivery, and rapid clearance from circulation, which seriously reduces the utilization rate. Affecting the uptake rate of EVs through engineering technologies is essential for therapeutic applications. Engineering strategies for customizing EV uptake can potentially overcome these limitations and enable desirable therapeutic uses of EVs. In this review, the mechanism and influencing factors of natural EV uptake will be described in detail. Targeting each EV uptake mechanism, the strategies of engineered EVs and their application in diseases will be emphatically discussed. Finally, the future challenges and perspectives of engineered EVs are presented multidimensionally.

Peptide L13S Derived from the BRN2 POU Domain Reduces Metastasis In Vivo and Inhibits Cell Migration and Invasion In Vitro

BACKGROUND/AIM

The Brain-Specific Homeobox/POU Domain Protein 2 (BRN2) transcription factor supports melanoma progression by regulating the expression of several genes involved in cell migration and invasion. We hypothesized that a peptide designed based on the POU domain of BRN2 could block the BRN2 transcription activity and, consequently, reduce metastasis.

MATERIALS AND METHODS

Cell viability was accessed by Trypan Blue exclusion dye assay and xCelligence platform. Wound-healing scratch assay and transwell invasion with matrigel membrane assay were performed to analyze cell migration and invasion. The internalization mechanism of the L13S peptide was investigated using confocal microscopy and wound-healing scratch assay. The impact of L13S on cell protein expression was analyzed through western blotting. In vivo assays were conducted to evaluate the protective effect and toxicity of L13S in a metastatic model using murine melanoma cells.

RESULTS

Here, we show that the peptide named L13S can inhibit the migration and invasion of murine melanoma cells (B16F10-Nex2) as well as the migration of human melanoma cells (SK-MEL-25 and A375) by regulating the expression of proteins involved in motility. Mechanistically, we found that L13S is internalized by murine melanoma cells via macropinocytosis and binds actin filaments and nuclei. More importantly, in vivo studies indicated that the peptide was able to significantly inhibit lung metastasis in syngeneic models without off-target effects and with virtually no cytotoxicity toward normal organs.

CONCLUSION

L13S peptide is a strong candidate for further development as an anticancer agent for the treatment of melanoma metastasis.

Different EGF-induced receptor dimer conformations for signaling and internalization

The structural basis of the activation and internalization of EGF receptors (EGFR) is still a matter of debate despite the importance of this target in cancer treatment. Whether agonists induce dimer formation or act on preformed dimers remains discussed. Here, we provide direct evidence that EGF-induced EGFR dimer formation as best illustrated by the very large increase in FRET between snap-tagged EGFR subunits induced by agonists. We confirm that Erlotinib-related TK (tyrosine kinase) inhibitors also induce dimer formation despite the inactive state of the binding domain. Surprisingly, TK inhibitors do not inhibit EGF-induced EGFR internalization despite their ability to fully block EGFR signaling. Only Erlotinib-related TK inhibitors promoting asymmetric dimers could slow down this process while the lapatinib-related ones have almost no effect. These results reveal that the conformation of the intracellular TK dimer, rather than the known EGFR signaling, is critical for EGFR internalization. These results also illustrate clear differences in the mode of action of TK inhibitors on the EGFR and open novel possibilities to control EGFR signaling for cancer treatment.

Intracellular Trafficking of Size-Tuned Nanoparticles for Drug Delivery

Polymeric nanoparticles (NPs) are widely used as drug delivery systems in nanomedicine. Despite their widespread application, a comprehensive understanding of their intracellular trafficking remains elusive. In the present study, we focused on exploring the impact of a 20 nm difference in size on NP performance, including drug delivery capabilities and intracellular trafficking. For that, poly(ethylene glycol) methyl ether-block-poly(lactide-co-glycolide) (PLGA-PEG) NPs with sizes of 50 and 70 nm were precisely tailored. To assess their prowess in encapsulating and releasing therapeutic agents, we have employed doxorubicin (Dox), a well-established anticancer drug widely utilized in clinical settings, as a model drug. Then, the beneficial effect of the developed nanoformulations was evaluated in breast cancer cells. Finally, we performed a semiquantitative analysis of both NPs' uptake and intracellular localization by immunostaining lysosomes, early endosomes, and recycling endosomes. The results show that the smaller NPs (50 nm) were able to reduce the metabolic activity of cancer cells more efficiently than NPs of 70 nm, in a time and concentration-dependent manner. These findings are corroborated by intracellular trafficking studies that reveal an earlier and higher uptake of NPs, with 50 nm compared to the 70 nm ones, by the breast cancer cells. Consequently, this study demonstrates that NP size, even in small increments, has an important impact on their therapeutic effect.

Generation and Characterization of SORT1-Targeted Antibody-Drug Conjugate for the Treatment of SORT1-Positive Breast Tumor

Antibody-drug conjugates (ADCs) have greatly improved the outcomes of advanced breast tumors. However, the treatment of breast tumors with existing ADCs is still hindered by many issues, such as tumor antigen heterogeneity and drug resistance. Therefore, ADCs against new targets would provide options for the treatment of these challenges. Sortilin-1 (SORT1) may be a promising target for ADC as it is upregulated in breast cancer. To evaluate the possibility of SORT1 as an ADC target, a humanized antibody_8D302 with high affinity against SORT1 was generated. Additionally, 8D302 was conjugated with MMAE and DXd to generate two ADCs_8D302-MMAE and 8D302-DXd, respectively. Both 8D302-MMAE and 8D302-DXd showed effective cytotoxicity against SORT1 positive breast tumor cell lines and induced bystander killing. Consequently, 8D302-MMAE showed relatively better anti-tumor activity than 8D302-DXd both in vitro and in vivo, but 8D302-DXd had superior safety profile and pharmacokinetics profile over 8D302-MMAE. Furthermore, SORT1 induced faster internalization and lysosomal trafficking of antibodies and had a higher turnover compared with HER2. Also, 8D302-DXd exhibited superior cell cytotoxicity and tumor suppression over trastuzumab-DXd, a HER2-targeted ADC. We hypothesize that the high turnover of SORT1 enables SORT1-targeted ADC to be a powerful agent for the treatment of SORT1-positive breast tumor.

Cellular Uptake and Cytotoxicity of Clostridium perfringens Iota-Toxin

Clostridium perfringens iota-toxin is composed of two separate proteins: a binding protein (Ib) that recognizes a host cell receptor and promotes the cellular uptake of a catalytic protein and (Ia) possessing ADP-ribosyltransferase activity that induces actin cytoskeleton disorganization. Ib exhibits the overall structure of bacterial pore-forming toxins (PFTs). Lipolysis-stimulated lipoprotein receptor (LSR) is defined as a host cell receptor for Ib. The binding of Ib to LSR causes an oligomer formation of Ib in lipid rafts of plasma membranes, mediating the entry of Ia into the cytoplasm. Ia induces actin cytoskeleton disruption via the ADP-ribosylation of G-actin and causes cell rounding and death. The binding protein alone disrupts the cell membrane and induces cytotoxicity in sensitive cells. Host cells permeabilized by the pore formation of Ib are repaired by a Ca2+-dependent plasma repair pathway. This review shows that the cellular uptake of iota-toxin utilizes a pathway of plasma membrane repair and that Ib alone induces cytotoxicity.

Existential Matters and Quality of Dying: A Model of Maturation Processes

Background: How people face mortality is a crucial matter for medicine. Yet, there is not a coherent and comprehensive understanding of how people can process the experience such that it is not traumatic. Methods: This article offers a "logic model" of how existential maturation occurs, using analogies from cell biology to explain the process. Results: This model depicts 10 mechanisms that together deal with mortality-salient events. Collectively, they are termed the existential function, which is seen as an innate, ever-evolving, integral part of the mind. An operational boundary selectively manages how realities are taken in. Processing is initiated with other essential people, ushering in reiterative steps of listening, finding, exploring, making meaning, and adjusting. The result is adaptive, integrated, mortality-acknowledging dispositions of mind. The process allows quality of life at the end of life and healthy mourning; impediments to it make for existential suffering and complicated grief. Conclusions: This conceptual model describes how people can face mortality. Its merit depends on its source in human experience, its explanatory power, its ability to guide people as they face mortality, and its ability to stimulate productive perspectives. It is therefore offered as an invitation for discussion, research, revision, and evolution.