Integrin Receptors Research Articles

Selective delivery of G-quadruplex ligand in glioma cell lines: the power of cyclic-RGD peptide

Compounds targeting non-canonical secondary structures of nucleic acids, known as G-quadruplexes, are highly cytotoxic, both for cancer and healthy cells, because of their action mechanism’s lack of appropriate selectivity. The targeted delivery of cytotoxic molecules to cancer cells is a valuable strategy to expand the repertoire of potential drugs, especially for cancer types for which new therapeutic tools are urgently needed, like glioblastoma. In this work, we conjugated a cyclic arginyl-glycyl-aspartic acid peptide to a naphthalene diimide, previously described as a highly performing stabilizing ligand for DNA G-quadruplexes, to specifically target glioma cells overexpressing RGD-binding integrin receptors. Our results, including confocal microscopy and cell toxicity assays, demonstrated improved efficacy and selective cellular absorption of the new conjugate without affecting the NDI’s ability to interact with the G4 target.

Mictlan-D3: A novel medium sized RGD-Disintegrin obtained from Crotalus mictlantecuhtli venom, in vitro tested against human breast Cancer and endothelial cells

Disintegrins are small non-enzymatic proteins present often at low concentration in the venom of viperid snakes. Isolated disintegrins are known for their lack of toxicity as well as their capacity to antagonize integrin receptors. Integrins are a major family of heterodimeric cell surface receptors that mediate cell-cell and cell-extracellular matrix (ECM) interactions. Integrins regulate key functions in cancer pathology and also tumor development. The aim of this study consisted in the isolation and characterization of disintegrins from rattlesnake new species Crotalus mictlantecutli venom. A disintegrin fraction obtained by RP-HPLC and named mictlan-D3, consist in two isoforms of 7439 and 7509 Da with 72 amino acid sequence containing the RGD binding motif. Mictlan-D3 inhibited MDA-MB-231 and HMEC-1 cell adhesion to laminin (LN), fibronectin (FN) and vitronectin (VN), highest inhibition was on MDA-MB-231 cell adhesion to LN by 81 % at 1 μM. The blockade of ⍺Vβ3 integrin was evaluated by wound healing migration assay. Mictlan-D3 inhibited MDA-MB-231 cell migration by 80 % and 38 % after 24 and 72 h of incubation respectively. HMEC-1 cell migration was inhibited by 67.6 % and 27.9 % after 24 and 72 h of incubation. Additionally, mictlan-D3. This work represent the first characterization of disintegrins from the Crotalus mictlantecutli venom.

Integrin-Specific Stimuli-Responsive Nanomaterials for Cancer Theranostics.

Background: Cancer is one of the leading causes of death worldwide. The tumor microenvironment makes the tumor difficult to treat, favoring drug resistance and the formation of metastases, resulting in death. Methods: Stimuli-responsive nanoparticles have shown great capacity to be used as a powerful strategy for cancer treatment, diagnostic, as well as theranostic. Nanocarriers are not only able to respond to internal stimuli such as oxidative stress, weakly acidic pH, high temperature, and the high expression of particular enzymes, but also to external stimuli such as light and paramagnetic characteristics to be exploited. Results: In this work, stimulus-responsive nanocarriers functionalized with arginine-glycine-aspartic acid (Arg-Gly-Asp) sequence as well as mimetic sequences with the capability to recognize integrin receptors are analyzed. Conclusions: This review highlights the progress that has been made in the development of new nanocarriers, capable of responding to endogenous and exogenous stimuli essential to combat cancer.

A Novel P-III Metalloproteinase from Bothrops barnetti Venom Degrades Extracellular Matrix Proteins, Inhibits Platelet Aggregation, and Disrupts Endothelial Cell Adhesion via α5β1 Integrin Receptors to Arginine-Glycine-Aspartic Acid (RGD)-Containing Molecules.

Viperid snake venoms are notably abundant in metalloproteinases (proteins) (SVMPs), which are primarily responsible for inducing hemorrhage and disrupting the hemostatic process and tissue integrity in envenomed victims. In this study, barnettlysin-III (Bar-III), a hemorrhagic P-III SVMP, was purified from the venom of the Peruvian snake Bothrops barnetti. Bar-III has a molecular mass of approximately 50 kDa and is a glycosylation-dependent functional metalloproteinase. Some biochemical properties of Bar-III, including the full amino acid sequence deduced from its cDNA, are reported. Its enzymatic activity is increased by Ca2+ ions and inhibited by an excess of Zn2+. Synthetic metalloproteinase inhibitors and EDTA also inhibit its proteolytic action. Bar-III degrades several plasma and ECM proteins, including fibrin(ogen), fibronectin, laminin, and nidogen. Platelets play a key role in hemostasis and thrombosis and in other biological process, such as inflammation and immunity, and platelet activation is driven by the platelet signaling receptors, glycoprotein (GP)Ib-IX-V, which binds vWF, and GPVI, which binds collagen. Moreover, Bar-III inhibits vWF- and convulxin-induced platelet aggregation in human washed platelets by cleaving the recombinant A1 domain of vWF and GPVI into a soluble ectodomain fraction of ~55 kDa (sGPVI). Bar-III does not reduce the viability of cultured endothelial cells; however, it interferes with the adhesion of these cells to fibronectin, vitronectin, and RGD peptides, as well as their migration profile. Bar-III binds specifically to the surface of these cells, and part of this interaction involves α5β1 integrin receptors. These results contribute to a better comprehension of the pathophysiology of snakebite accidents/incidents and could be used as a tool to explore novel and safer anti-venom therapeutics.

Exploring the Current Potential of Snake Venom Disintegrins as Chemotherapeutic Agents: A Narrative Update on their Clinical Translational Potential

A potential source of multiple enzymatic and nonenzymatic molecules that protect the host is snake venom. In these venoms, several kinds of peptides that have significant beneficial effects were discovered and characterized. Disintegrins act by blocking integrins on transmembrane cell surfaces, inhibiting tumor cells from adhering, migrating, forming new blood vessels, and spreading. This has an important effect on delaying the development, neovascularization, and growth of tumors. These cells are ideal candidates for novel therapies for the management of malignancies due to their tumor selectivity and decreased size. As research findings in various <i>in vivo</i> & <i>in vitro</i>, disintegrin proteins are low-molecular-weight polypeptides that are found in the venom of vipers and rattle snakes. They act by blocking the β1 and β3 integrin receptors. Angiogenesis and metastatic processes in cancer are mediated through β1 and β3 integrins. Hence, blocking β1 and β3 integrin receptors plays a prominent role in blocking the progression of cancer, and disintegrins seem to be promising candidates for antineoplastic therapies. The disintegrins with anticancer properties include Crotatroxin 2, Alternagin-C, Rubistatin, Leucurogin, Mojastin- 1, Contortrostatin, Acostatin, Vicrostatin, Tzabcan, Eristostatin, Purpureomaculatus, Saxatilin, Lebein, Salmosin, and Rhodostomin. The above mentioned disintegrins were considered in this study. This review is based on the origins of these disintegrins, their modes of targeting, their categorization, and their inherent anticancer potential.

An RGD-Conjugated Prodrug Nanoparticle with Blood-Brain-Barrier Penetrability for Neuroprotection Against Cerebral Ischemia-Reperfusion Injury.

Cerebral ischemia-reperfusion injury significantly contributes to global morbidity and mortality. Loganin is a natural product with various neuroprotective effects; however, it lacks targeted specificity for particular cells or receptors, which may result in reduced therapeutic efficacy and an increased risk of side effects. To address the limitations of loganin, we developed LA-1, a novel compound incorporating an Arg-Gly-Asp (RGD) peptide to target integrin receptor αvβ3, enhancing brain-targeting efficacy. LA-1 exhibited optimal nanoscale properties, significantly improved cell viability, reduced ROS production, and enhanced survival rates in vitro. In vivo, LA-1 decreased infarct sizes, improved neurological function, and reduced oxidative stress and neuroinflammation. Proteomic analysis showed LA-1 modulates PI3K/Akt and Nrf2/HO-1 pathways, providing targeted neuroprotection. These findings suggest LA-1's potential for clinical applications in treating cerebral ischemia-reperfusion injury.

Effect and mechanism of Adipokine Omentin-1 on cardiac hypertrophy in heart failure with preserved ejection fraction

Abstract Background Omentin-1 secreted by epicardial adipose tissue can inhibit ventricular remodeling and improve early cardiac function after myocardial infarction. Our previous studies have identified the omentin-1 receptor as integrin receptors αvβ3 and αvβ5. However, the effect of omentin-1 on heart failure with preserved ejection fraction (HFpEF) remains poorly understood. Purpose The present study aims to study the role and mechanism of omentin-1 in cardiac function and myocardial cell structure in HFpEF. Methods and Results The influences of omentin-1 were investigated in HFpEF mice (HFD (60% calories from lard) and L-NAME (0.5 g/L in drinking water)), which were treated in vivo. Echocardiography showed better diastolic function in HFpEF mice treated with omentin-1 (5 ug/kg/h) subcutaneously for 4 weeks, and tissue staining showed alleviated myocardial fibrosis and myocardial hypertrophy. The RNA sequencing analysis revealed variations in the gene expression related to ketone body metabolism in HFpEF mice after omentin-1 treatment (600 ng/ml). The supernatant was obtained from mouse bone marrow macrophages treated with ultrapure endotoxin and ATP and was utilized as the macrophage-conditioned medium for culturing primary cardiomyocytes, which were stimulated with isoproterenol for 48 hours to construct the HFpEF cardiomyocyte model. In the heart tissue of HFpEF mice and HFpEF cardiomyocytes treated with omentin-1, there was a notable increase in the expression of a pivotal enzyme of ketone body metabolism- succinyl-CoA transferase (SCOT), and a decrease in the expression of hypertrophy signal. The myocardial hypertrophy model was established by stimulating the myocardial cell line H9C2 with isoproterenol. Following the inhibition of the integrin receptor and PI3K-AKT pathway, the impacts of omentin-1 on SCOT and myocardial hypertrophy signal expression in hypertrophic cardiomyocytes were eliminated. Conclusion This study provides evidence for the effects of omentin-1 on cardiac function and myocardial structure in HFpEF and proposes that omentin-1 may stimulate the downstream PI3K/AKT pathway via integrin receptors on cardiomyocytes, leading to increased expression of SCOT and improvement of cardiomyocyte hypertrophy.

Proteomic profiling reveals CEACAM6 function in driving gallbladder cancer aggressiveness through integrin receptor, PRKCD and AKT/ERK signaling

Gallbladder cancer (GBC) presents as an aggressive malignancy with poor patient outcome. Like other epithelial cancers, the mechanisms of GBC cancer progression remain vague and efforts in finding targeted therapies fall below expectations. This study combined proteomic analysis of formalin-fixed paraffin-embedded (FFPE) GBC samples, functional and molecular characterization of potential oncogenes and identification of potential therapeutic strategies for GBC. We identified Carcinoembryonic Antigen-related Cell Adhesion Molecule 6 (CEACAM6) as one of the significantly most upregulated proteins in GBC. CEACAM6 overexpression has been observed in other cancer entities but the molecular function remains unclear. Our functional analyses in vitro and in vivo mouse models revealed that CEACAM6 supported the initial steps of cancer progression and metastasis by decreasing cell adhesion and promoting migration and invasion of GBC cells. Conversely, CEACAM6 knockdown abolished GBC aggressiveness by increasing cell adhesion while reducing cell migration, cell proliferation, and colony formation. BirA-BioID followed by mass-spectrometry revealed Integrin Beta-1 (ITGB1) and Protein Kinase C Delta (PRKCD) as direct molecular and functional partners of CEACAM6 supporting GBC cell migration. ERK and AKT signaling and their downstream target genes were regulated by CEACAM6 and thus the treatment with AKT inhibitor capivasertib or ERK inhibitor ulixertinib mitigated the CEACAM6-induced migration. These findings demonstrate that CEACAM6 is crucially involved in gallbladder cancer progression by promoting migration and inhibiting cell adhesion through ERK and AKT signaling providing specific options for treatment of CEACAM6-positive cancers.

Synthetic hydrogel substrate for human induced pluripotent stem cell definitive endoderm differentiation

Human induced pluripotent stem cells (hiPSCs) can give rise to multiple lineages derived from three germ layers, endoderm, mesoderm and ectoderm. Definitive endoderm (DE) cell types and tissues have great potential for regenerative medicine applications. Current hiPSC differentiation protocols focus on the addition of soluble factors; however, extracellular matrix properties are known to also play a role in dictating cell fate. Matrigel™ is the gold standard for DE differentiation, but this xenogeneic, poorly defined basement membrane extract limits the clinical translatability of DE-derived tissues. Here we present a fully defined PEG-based hydrogel substrate to support hiPSC-derived DE differentiation. We screened hydrogel formulations presenting different adhesive peptides and matrix stiffness. Our results demonstrate that presenting a short peptide, cyclic RGD, on the engineered PEG hydrogel supports the transition from undifferentiated hiPSCs to DE using a serum-free, commercially available kit. We show that increasing substrate stiffness (G’ = 1.0–4.0 kPa) results in an increased linear response in DE differentiation efficiency. We also include a temporal analysis of the expression of integrin and syndecan receptors as the hiPSCs undergo specification towards DE lineage. Finally, we show that focal adhesion kinase activity regulates hiPSC growth and DE differentiation efficiency. Overall, we present a fully defined matrix as a synthetic alternative for Matrigel™ supporting DE differentiation.

RGD peptide promotes follicle growth through integrins αvβ3/αvβ5 in three-dimensional culture.

Three-dimensional ovarian tissue culture is a unique model to define the effects of molecules on folliculogenesis. Using this model, we determined that RGD-integrin interaction plays a role in antrum formation and theca cell differentiation. We recently developed a three-dimensional (3D) ovarian tissue culture system supported by bacterial-derived dextran hydrogel. Arg-Gly-Asp (RGD) is an extracellular matrix-derived triple peptide. Immature ovarian tissues cultured in RGD-modified dextran hydrogel significantly promoted antral follicle growth and oocyte quality compared with those cultured in dextran hydrogel alone. In this study, we examined the mechanism of follicle growth stimulated by RGD treatment in the 3D system. First, we detected that direct contact between RGD-modified dextran hydrogel and ovarian interstitial cells is necessary to promote antral follicle growth. Therefore, we hypothesized that RGD stimulates antral follicle growth through RGD-binding integrin receptors expressed in the interstitial cell mass. Using quantitative PCR (qPCR) and immunochemical staining, we identified that integrins ⍺vβ3 and ⍺v5 are predominantly expressed in the ovarian interstitial compartment. To assess the effect of RGD-integrin interaction on follicle growth, ovarian tissues were cultured with cilengitide (Ci), an inhibitor specific for ⍺vβ3 and ⍺vβ5. Ci treatment suppressed RGD-induced follicle growth and oocyte quality in a dose-dependent manner. When the interstitial cell aggregates were cultured with RGD, cell migration and theca-related gene expression were significantly upregulated. Ci treatment dramatically suppressed these RGD-induced activities. In coculturing the interstitial aggregate and secondary follicles with RGD, migrating cells formed the outermost cell layers around the follicles, like theca layers, which were totally blocked by Ci treatment. In conclusion, our results suggest that RGD stimulates theca cell differentiation in the ovarian interstitial cells through integrins ⍺vβ3 and ⍺v5 to promote antral follicle growth in our 3D system.

Preventing osteoporotic bone loss in mice by promoting balanced bone remodeling through M-CSFRGD, a dual antagonist to c-FMS and αvβ3 receptors

Osteoporosis is a common, age-related disease caused by imbalanced bone remodeling. Current treatments either shut down bone resorption or robustly stimulate bone formation. Here, we describe a novel compound that inhibits osteoclast activity without causing apparent disruptions to bone formation by targeting both c-FMS (i.e., osteoclast differentiation) and αvβ3 integrin (i.e., osteoclastic bone resorption) receptors. We show that human serum albumin (HSA)-conjugated M-CSFRGD protein (M-CSFRGD-HSA) effectively inhibits the activity of both receptors, with a three-fold higher serum half-life compared to the unconjugated M-CSFRGD. We then treated ovariectomized mice with different doses of M-CSFRGD-HSA, alendronate, or a monospecific control protein. The bispecific M-CSFRGD-HSA was superior to a monospecific control in alleviating bone loss and reducing osteoclast distribution and function. M-CSFRGD-HSA and alendronate effectively prevented ovariectomy-induced bone loss, but M-CSFRGD-HSA had a milder inhibitory effect on osteoclast distribution and activity. Moreover, alendronate halted bone formation, while M-CSFRGD-HSA-treated mice showed an increased level of serum amino-terminal propeptide of type I collagen, a bone formation marker. Our data indicate that the mild reduction in osteoclast activity facilitated by the bispecific M-CSFRGD-HSA allows the maintenance of certain levels of bone formation and may be superior to treatments that induce osteoclast depletion.

Strain-dependent glutathionylation of fibronectin fibers impacts mechano-chemical behavior and primes an integrin switch

The extracellular matrix (ECM) is a protein polymer network that physically supports cells within a tissue. It acts as an important physical and biochemical stimulus directing cell behaviors. For fibronectin (Fn), a predominant component of the ECM, these physical and biochemical activities are inextricably linked as physical forces trigger conformational changes that impact its biochemical activity. Here, we analyze whether oxidative post-translational modifications, specifically glutathionylation, alter Fn’s mechano-chemical characteristics through stretch-dependent protein modification. ECM post-translational modifications represent a potential for time- or stimulus-dependent changes in ECM structure-function relationships that could persist over time with potentially significant impacts on cell and tissue behaviors. In this study, we show evidence that glutathionylation of Fn ECM fibers is stretch-dependent and alters Fn fiber mechanical properties with implications on the selectivity of engaging integrin receptors. These data demonstrate the existence of multimodal post-translational modification mechanisms within the ECM with high relevance to the microenvironmental regulation of downstream cell behaviors.

The role and regulation of integrins in cell migration and invasion.

Integrin receptors are the main molecular link between cells and the extracellular matrix (ECM) as well as mediating cell-cell interactions. Integrin-ECM binding triggers the formation of heterogeneous multi-protein assemblies termed integrin adhesion complexes (IACs) that enable integrins to transform extracellular cues into intracellular signals that affect many cellular processes, especially cell motility. Cell migration is essential for diverse physiological and pathological processes and is dysregulated in cancer to favour cell invasion and metastasis. Here, we discuss recent findings on the role of integrins in cell migration with a focus on cancer cell dissemination. We review how integrins regulate the spatial distribution and dynamics of different IACs, covering classical focal adhesions, emerging adhesion types and adhesion regulation. We discuss the diverse roles integrins have during cancer progression from cell migration across varied ECM landscapes to breaching barriers such as the basement membrane, and eventual colonization of distant organs.

Theranostic Approaches for Gastric Cancer: An Overview of In Vitro and In Vivo Investigations

Gastric cancer (GC) is the second most common cause of cancer-related death worldwide and a serious public health concern. This high death rate is mostly caused by late-stage diagnoses, which lead to poor treatment outcomes. Radiation immunotherapy and targeted therapies are becoming increasingly popular in GC treatment, in addition to surgery and systemic chemotherapy. In this review, we have focused on both in vitro and in vivo research, which presents a summary of recent developments in targeted therapies for gastric cancer. We explore targeted therapy approaches, including integrin receptors, HER2, Claudin 18, and glutathione-responsive systems. For instance, therapies targeting the integrin receptors such as the αvβ3 and αvβ5 integrins have shown promise in enhancing diagnostic precision and treatment efficacy. Furthermore, nanotechnology provides novel approaches to targeted drug delivery and imaging. These include glutathione-responsive nanoplatforms and cyclic RGD peptide-conjugated nanoparticles. These novel strategies seek to reduce systemic toxicity while increasing specificity and efficacy. To sum up, the review addresses the significance of personalized medicine and advancements in gastric cancer-targeted therapies. It explores potential methods for enhancing gastric cancer prognosis and treatment in the future.

MicroRNA-375 modulates neutrophil chemotaxis via targeting Cathepsin B in zebrafish

Neutrophils are crucial for defense against numerous infections, and their migration and activations are tightly regulated to prevent collateral tissue damage. We previously performed a neutrophil-specific miRNA overexpression screening and identified several microRNAs, including miR-375, as potent modulators for neutrophil activity. Overexpression of miR-375 decreases neutrophil motility and migration in zebrafish and human neutrophil-like cells. We screened the genes downregulated by miR-375 in zebrafish neutrophils and identified that Cathepsin B (Ctsba) is required for neutrophil motility and chemotaxis upon tail wounding and bacterial infection. Pharmacological inhibition or neutrophil-specific knockout of ctsba significantly decreased the neutrophil chemotaxis in zebrafish and survival upon systemic bacterial infection. Notably, Ctsba knockdown in human neutrophil-like cells also resulted in reduced chemotaxis. Inhibiting integrin receptor function using RGDS rescued the neutrophil migration defects and susceptibility to systemic infection in zebrafish with either miR-375 overexpression or ctsba knockout. Our results demonstrate that miR-375 and its target Ctsba modulate neutrophil activity during tissue injury and bacterial infection in vivo, providing novel insights into neutrophil biology and the overall inflammation process.

Novel RGD-decorated micelles loaded with doxorubicin for targeted breast cancer chemotherapy

Nanotechnology has emerged as a promising innovative avenue for therapeutic intervention in cancer research. However, achieving satisfactory accumulation of nanoparticles in the tumor and fabricating optimized nanoparticles remain challenging. In this work, we developed a novel polymeric micelle system to actively target integrin receptors, which are usually overexpressed in breast cancer. We first synthesized a targeted peptide-modified cyclic (Arg-Gly-Asp-D-Phe-Cys) (c(RGDfc))-polyethylene glycol-acitretin amphipathic conjugate (RPA) and prepared doxorubicin (DOX)-loaded RPADm (RPA@DOX) micelles with a high drug loading content of more than 11 %. Compared with unmodified DOX-containing micelles, RPADm demonstrated increased cytotoxicity and cellular uptake by MCF-7 cells. Importantly, competitive binding experiments confirmed that the observed enhancement effect was attributed to the modification of c(RGDfc) on the surface of the micelles. Furthermore, due to its active tumor-targeting ability, compared with the other DOX-based formulations, the RPADm exhibited the highest tumor distribution and strongest therapeutic efficacy in MCF-7 tumor-bearing nude mice. Additionally, the safety evaluation experiments revealed that the DOX-loaded micelles had no obvious systemic toxicity. These results suggest that the developed micelles modified with c(RGDfc) are promising candidates for tumor-active targeting therapies.

Collagen I Increases Palmitate-Induced Lipotoxicity in HepG2 Cells via Integrin-Mediated Death.

Various strategies have been employed to improve the reliability of 2D, 3D, and co-culture in vitro models of nonalcoholic fatty liver disease, including using extracellular matrix proteins such as collagen I to promote cell adhesion. While studies have demonstrated the significant benefits of culturing cells on collagen I, its effects on the HepG2 cell line after exposure to palmitate (PA) have not been investigated. Therefore, this study aimed to assess the effects of PA-induced lipotoxicity in HepG2 cultured in the absence or presence of collagen I. HepG2 cultured in the absence or presence of collagen I was exposed to PA, followed by analyses that assessed cell proliferation, viability, adhesion, cell death, mitochondrial respiration, reactive oxygen species production, gene and protein expression, and triacylglycerol accumulation. Culturing HepG2 on collagen I was associated with increased cell proliferation, adhesion, and expression of integrin receptors, and improved cellular spreading compared to culturing them in the absence of collagen I. However, PA-induced lipotoxicity was greater in collagen I-cultured HepG2 than in those cultured in the absence of collagen I and was associated with increased α2β1 receptors. In summary, the present study demonstrated for the first time that collagen I-cultured HepG2 exhibited exacerbated cell death following exposure to PA through integrin-mediated death. The findings from this study may serve as a caution to those using 2D models or 3D scaffold-based models of HepG2 in the presence of collagen I.

Peptide-functionalized gold nanoparticles for boron neutron capture therapy with the potential to use in Glioblastoma treatment

Glioblastoma is a highly aggressive glioma with limited treatment options. Boron neutron capture therapy (BNCT) offers a promising approach for refractory cancers, utilizing boron-10 (10B) and thermal neutrons to generate cytotoxic particles. Effective BNCT depends on selective targeting and retention of 10B in tumors. Current BNCT drugs face issues with rapid clearance and poor tumor accumulation. To address this, we developed gold nanoparticles (AuNPs) functionalized with cyclic arginine-glycine-aspartic acid (cRGD) peptides as a nanocarrier for Sodium Mercaptododecaborate (BSH), resulting in AuNPs-BSH&PEG-cRGD. In vitro, AuNPs-BSH&PEG-cRGD increased 10B content in GL261 glioma cells by approximately 2.5-fold compared to unmodified AuNPs-BSH&PEG, indicating enhanced targeting due to cRGD's affinity for integrin receptor αvβ3. In a subcutaneous glioma mouse model, 6 h post-intratumoral administration, the 10B concentration in tumors was 17.98 μg/g for AuNPs-BSH&PEG-cRGD, significantly higher than 0.45 μg/g for BSH. The tumor-to-blood (T/B) and tumor-to-normal tissue (T/N) ratios were also higher for AuNPs-BSH&PEG-cRGD, suggesting improved targeting and retention. This indicates that AuNPs-BSH&PEG-cRGD may enhance BNCT efficacy and minimize normal tissue toxicity. In summary, this study provides a novel strategy for BSH delivery and may broaden the design vision of BNCT nano-boron capture agents.

Bone sialoprotein stimulates cancer cell adhesion through the RGD motif and the αvβ3 and αvβ5 integrin receptors.

Being implicated in bone metastasis development, bone sialoprotein (BSP) expression is upregulated in patients with cancer. While BSP regulates cancer cell adhesion to the extracellular matrix, to the best of our knowledge, the specific adhesive molecular interactions in metastatic bone disease remain unclear. The present study aimed to improve the understanding of the arginine-glycine-aspartic acid (RGD) sequence of BSP and the integrin receptors αvβ3 and αvβ5 in BSP-mediated cancer cell adhesion. Human breast cancer (MDA-MB-231), prostate cancer (PC-3) and non-small cell lung cancer (NSCLC; NCI-H460) cell lines were cultured on BSP-coated plates. Adhesion assays with varying BSP concentrations were performed to evaluate the effect of exogenous glycine-arginine-glycine-aspartic acid-serine-proline (GRGDSP) peptide and anti-integrin antibodies on the attachment of cancer cells to BSP. Cell attachment was assessed using the alamarBlue® assay. The present results indicated that BSP supported the adhesion of cancer cells. The RGD counterpart GRGDSP peptide reduced the attachment of all tested cancer cell lines to BSP by ≤98.4%. Experiments with anti-integrin antibodies demonstrated differences among integrin receptors and cancer cell types. The αvβ5 antibody decreased NSCLC cell adhesion to BSP by 84.3%, while the αvβ3 antibody decreased adhesion by 14%. The αvβ3 antibody decreased PC-3 cell adhesion to BSP by 46.4%, while the αvβ5 antibody decreased adhesion by 9.5%. Adhesion of MDA-MB-231 cells to BSP was inhibited by 54.7% with αvβ5 antibody. The present results demonstrated that BSP-induced cancer cell adhesion occurs through the binding of the RGD sequence of BSP to the cell integrin receptors αvβ3 and αvβ5. Differences between cancer types were found regarding the mediation via αvβ3 or αvβ5 receptors. The present findings may explain why certain cancer cells preferentially spread to the bone tissue, suggesting that targeting the RGD-integrin binding interaction could be a promising novel cancer treatment option.

Phosphorylated vimentin-triggered fibronectin matrix disaggregation enhances the dissemination of Treponema pallidum subsp. pallidum across the microvascular endothelial barrier.

Fibronectin (FN) is an essential component of the extracellular matrix (ECM) that protects the integrity of the microvascular endothelial barrier (MEB). However, Treponema pallidum subsp. pallidum (Tp) breaches this barrier through elusive mechanisms and rapidly disseminates throughout the host. We aimed to understand the impact of Tp on the surrounding FN matrix of MEB and the underlying mechanisms of this effect. In this study, immunofluorescence assays (IF) were conducted to assess the integrity of the FN matrix surrounding human microvascular endothelial cell-1 (HMEC-1) with/without Tp co-culture, revealing that only live Tp exhibited the capability to mediate FN matrix disaggregation in HMEC-1. Western blotting and IF were employed to determine the protein levels associated with the FN matrix during Tp infection, which showed the unaltered protein levels of total FN and its receptor integrin α5β1, along with reduced insoluble FN and increased soluble FN. Simultaneously, the integrin α5β1-binding protein-intracellular vimentin maintained a stable total protein level while exhibiting an increase in the soluble form, specifically mediated by the phosphorylation of its 39th residue (pSer39-vimentin). Besides, this process of vimentin phosphorylation, which could be hindered by a serine-to-alanine mutation or inhibition of phosphorylated-AKT1 (pAKT1), promoted intracellular vimentin rearrangement and FN matrix disaggregation. Moreover, within the introduction of additional cellular FN rather than other Tp-adhered ECM protein, in vitro endothelial barrier traversal experiment and in vivo syphilitic infectivity test demonstrated that viable Tp was effectively prevented from penetrating the in vitro MEB or disseminating in Tp-challenged rabbits. This investigation revealed the active pAKT1/pSer39-vimentin signal triggered by live Tp to expedite the disaggregation of the FN matrix and highlighted the importance of FN matrix stability in syphilis, thereby providing a novel perspective on ECM disruption mechanisms that facilitate Tp dissemination across the MEB.