The drug release of PLGA-based nanoparticles and their application in treatment of gastrointestinal cancers.

The poly (lactic-co-glycolic acid) (PLGA) based nanoparticles have been applied for drug delivery due to their simple preparation, biodegradability, and ideal biocompatibility. In this study, the factors affecting the degradation of PLGA-based nanoparticles are reviewed, encompassing the ratio of PLA to PGA, relative molecular weight, crystallinity, and preparation process of PLGA nanoparticles. The drug release behavior of PLGA-based nanoparticles, such as the degradation environment, encapsulated drug properties of polymers, and drug loading rates, are also discussed. Since gastrointestinal cancer is one of the major global threats to human health, this paper comprehensively summarizes the application of PLGA nanoparticles in gastrointestinal cancers from diagnosis, chemotherapy, radiotherapy, and novel tumor treatment methods (immunotherapy, gene therapy, and photothermal therapy). Finally, the future application of PLGA-based drug delivery systems in treating gastrointestinal cancers is discussed. The bottleneck of application status and the prospect of PLGA-nanoparticles in gastrointestinal tumor application are presented. To truly realize the great and wide application of PLGA-based nanoparticles, collaborative progress in the field of nanomaterials and life sciences is needed.

PrivShieldROS: An Extended Robot Operating System Integrating Ethereum and Interplanetary File System for Enhanced Sensor Data Privacy.

With the application of robotics in security monitoring, medical care, image analysis, and other high-privacy fields, vision sensor data in robotic operating systems (ROS) faces the challenge of enhancing secure storage and transmission. Recently, it has been proposed that the distributed advantages of blockchain be taken advantage of to improve the security of data in ROS. Still, it has limitations such as high latency and large resource consumption. To address these issues, this paper introduces PrivShieldROS, an extended robotic operating system developed by InterPlanetary File System (IPFS), blockchain, and HybridABEnc to enhance the confidentiality and security of vision sensor data in ROS. The system takes advantage of the decentralized nature of IPFS to enhance data availability and robustness while combining HybridABEnc for fine-grained access control. In addition, it ensures the security and confidentiality of the data distribution mechanism by using blockchain technology to store data content identifiers (CID) persistently. Finally, the effectiveness of this system is verified by three experiments. Compared with the state-of-the-art blockchain-extended ROS, PrivShieldROS shows improvements in key metrics. This paper has been partly submitted to IROS 2024.

[Remediation Effect of Two Iron-modified Biochars on Slightly Alkaline Arsenic and Cadmium Contaminated Soil].

As a good passivation agent for heavy metals, modified biochar has been widely used in environmental remediation. In order to explore the effects of different modification methods on arsenic (As) and cadmium (Cd) passivation in soil by biochar, this study used co-precipitation and impregnation pyrolysis to prepare iron-modified biochar. Through adsorption experiments and soil culture experiments, the properties of biochar, adsorption capacity, and the As and Cd passivation ability in soil were analyzed. The results showed that both modification methods could increase the iron (Fe) content and zero charge point of biochar, and the Fe minerals supported by Fe-modified biochar (FeBC-1) prepared by co-precipitation were mainly Fe3O4, FeO(OH), and γ-Fe2O3. The Fe-modified biochar (FeBC-2) prepared by impregnation pyrolysis mainly consisted of α-Fe2O3 and γ-Fe2O3. FeBC-1 showed strong adsorption and removal ability for As and Cd, with a removal rate of 21.40%-34.14%, which could significantly promote the conversion of non-obligate adsorbed As to residual As in soil, whereas FeBC-2 only had a good adsorption effect on As. The adsorption capacity of BC, FeBC-1, and FeBC-2 for Cd were proportional to their CEC. The adsorption and removal effect of BC on Cd was better than that of FeBC-1 and FeBC-2, which could significantly promote the conversion of soil acid-soluble Cd to stable residue Cd.

Disrupting the platelet internal membrane via PI3KC2α inhibition impairs thrombosis independently of canonical platelet activation.

Arterial thrombosis causes heart attacks and most strokes and is the most common cause of death in the world. Platelets are the cells that form arterial thrombi, and antiplatelet drugs are the mainstay of heart attack and stroke prevention. Yet, current drugs have limited efficacy, preventing fewer than 25% of lethal cardiovascular events without clinically relevant effects on bleeding. The key limitation on the ability of all current drugs to impair thrombosis without causing bleeding is that they block global platelet activation, thereby indiscriminately preventing platelet function in hemostasis and thrombosis. Here, we identify an approach with the potential to overcome this limitation by preventing platelet function independently of canonical platelet activation and in a manner that appears specifically relevant in the setting of thrombosis. Genetic or pharmacological targeting of the class II phosphoinositide 3-kinase (PI3KC2α) dilates the internal membrane reserve of platelets but does not affect activation-dependent platelet function in standard tests. Despite this, inhibition of PI3KC2α is potently antithrombotic in human blood ex vivo and mice in vivo and does not affect hemostasis. Mechanistic studies reveal this antithrombotic effect to be the result of impaired platelet adhesion driven by pronounced hemodynamic shear stress gradients. These findings demonstrate an important role for PI3KC2α in regulating platelet structure and function via a membrane-dependent mechanism and suggest that drugs targeting the platelet internal membrane may be a suitable approach for antithrombotic therapies with an improved therapeutic window.

Synthesis and biological evaluation of 8-aryl-2-morpholino-7-O-substituted benzo[e][1,3]oxazin-4-ones against DNA-PK, PI3K, PDE3A enzymes and platelet aggregation.

A series of 40 7-(O-substituted)-2-morpholino-8-aryl-4H-benzo[e][1,3]oxazin-4-one derivatives was synthesized. They were prepared via synthesis of a key precursor, 8-bromo-7-hydroxy-2-morpholino-4H-benzo[e][1,3]oxazin-4-one 13 which was amenable to ether synthesis at the 7-position and Suzuki coupling at the 8-position. The 2 protons of 7-OCH2 in compounds 18g, 18h, 18i, 18l and 18m prove to be magnetically non-equivalent, atropisomerism (axial chirality), as result of sterically hindered rotation of the bulky 8-aryl-substituent. The products were evaluated for their activities against PI3K isoforms, DNA-PK and PDE3. The results showed that this substitution pattern has a deleterious effect on PI3K activities, which may arise from steric hindrance in the active site. PI3Kδ was somewhat more tolerant of this substitution particularly where 8-(4-methoxylphenyl) substituents were present (IC50s∼2-3µM). Good activities against PDE3 were also obtained for compounds, with particular members of the 7-(2-pyridinyl) methoxy series 19 showing good inhibition (IC50s∼2-3µM), comparable to previously described analogues. A piperazinyl derivative 26a effectively inhibited ADP-induced platelet aggregation with an IC50 of 8µM.

Corrigendum: 14-3-3ζ regulates the mitochondrial respiratory reserve linked to platelet phosphatidylserine exposure and procoagulant function.

This corrects the article DOI: 10.1038/ncomms12862.

Inhibition of NMDA receptor function with an anti-GluN1-S2 antibody impairs human platelet function and thrombosis.

GluN1 is a mandatory component of N-methyl-D-aspartate receptors (NMDARs) best known for their roles in the brain, but with increasing evidence for relevance in peripheral tissues, including platelets. Certain anti-GluN1 antibodies reduce brain infarcts in rodent models of ischaemic stroke. There is also evidence that human anti-GluN1 autoantibodies reduce neuronal damage in stroke patients, but the underlying mechanism is unclear. This study investigated whether anti-GluN1-mediated neuroprotection involves inhibition of platelet function. Four commercial anti-GluN1 antibodies were screened for their abilities to inhibit human platelet aggregation. Haematological parameters were examined in rats vaccinated with GluN1. Platelet effects of a mouse monoclonal antibody targeting the glycine-binding region of GluN1 (GluN1-S2) were tested in assays of platelet activation, aggregation and thrombus formation. The epitope of anti-GluN1-S2 was mapped and the mechanism of antibody action modelled using crystal structures of GluN1. Our work found that rats vaccinated with GluN1 had a mildly prolonged bleeding time and carried antibodies targeting mostly GluN1-S2. The monoclonal anti-GluN1-S2 antibody (from BD Biosciences) inhibited activation and aggregation of human platelets in the presence of adrenaline, adenosine diphosphate, collagen, thrombin and a protease-activated receptor 1-activating peptide. When human blood was flowed over collagen-coated surfaces, anti-GluN1-S2 impaired thrombus growth and stability. The epitope of anti-GluN1-S2 was mapped to α-helix H located within the glycine-binding clamshell of GluN1, where the antibody binding was computationally predicted to impair opening of the NMDAR channel. Our results indicate that anti-GluN1-S2 inhibits function of human platelets, including dense granule release and thrombus growth. Findings add to the evidence that platelet NMDARs regulate thrombus formation and suggest a novel mechanism by which anti-GluN1 autoantibodies limit stroke-induced neuronal damage.

Synthesis of linear and angular aryl-morpholino-naphth-oxazines, their DNA-PK, PI3K, PDE3A and antiplatelet activity.

To continue our study of 2-morpholino-benzoxazine based compounds, which show useful activity against PI3K family enzymes or antiplatelet activity, we designed and synthesized a series of linear 6.7-fused, 5,6-angular fused and 7,8-angular fused-aryl-morpholino-naphth-oxazines. The compounds were prepared from substituted 2-hydroxynaphthoic acid to give the corresponding thioxo analogues 8, 9, 15 and 19. The thioxo products were then converted to the morpholino substituted analogue. The aryl group was introduced by Suzuki coupling of bromo precursors. The products were evaluated for activity at PI3K family enzymes and as platelet aggregation inhibitors and compared to reported unsubstituted analogues. The linear 6.7-fused product 13a and 13b were moderated potent but selective PI3Kδ isoform inhibitors (IC50=7.7 and 5.61µM). Good antiplatelet activity was noticed for the angular 7,8-fused compounds 22a, b, k and l with IC50=3.0,14.0, 2.0 and 5.0µM respectively. The antiplatelet activity is independent of PDE3.

14-3-3ζ regulates the mitochondrial respiratory reserve linked to platelet phosphatidylserine exposure and procoagulant function.

The 14-3-3 family of adaptor proteins regulate diverse cellular functions including cell proliferation, metabolism, adhesion and apoptosis. Platelets express numerous 14-3-3 isoforms, including 14-3-3ζ, which has previously been implicated in regulating GPIbα function. Here we show an important role for 14-3-3ζ in regulating arterial thrombosis. Interestingly, this thrombosis defect is not related to alterations in von Willebrand factor (VWF)-GPIb adhesive function or platelet activation, but instead associated with reduced platelet phosphatidylserine (PS) exposure and procoagulant function. Decreased PS exposure in 14-3-3ζ-deficient platelets is associated with more sustained levels of metabolic ATP and increased mitochondrial respiratory reserve, independent of alterations in cytosolic calcium flux. Reduced platelet PS exposure in 14-3-3ζ-deficient mice does not increase bleeding risk, but results in decreased thrombin generation and protection from pulmonary embolism, leading to prolonged survival. Our studies define an important role for 14-3-3ζ in regulating platelet bioenergetics, leading to decreased platelet PS exposure and procoagulant function.

Development of single and mixed isoform selectivity PI3Kδ inhibitors by targeting Asn836 of PI3Kδ.

A series of PI3Kδ inhibitors derived from the pan-PI3K inhibitor ZSTK474 was prepared that target a non-conserved region of the catalytic site. Dependent upon the substituents present, these analogues show different levels of isoform selectivity and sensitivity to the mutation N836D in PI3Kδ. As a marker of 'on-target' activity and permeability, a selection of the most potent PI3Kδ inhibitors were shown to inhibit pAkt production in the Nawalma Burkitt lymphoma cell line.

Discovery and antiplatelet activity of a selective PI3Kß inhibitor (MIPS-9922).

A series of amino-substituted triazines were developed and examined for PI3Kß inhibition and anti-platelet function. Structural adaptations of a morpholine ring of the prototype pan-PI3K inhibitor ZSTK474 yielded PI3Kß selective compounds, where the selectivity largely derives from an interaction with the non-conserved Asp862 residue, as shown by site directed mutagenesis. The most PI3Kß selective inhibitor from the series was studied in detail through a series of in vitro and in vivo functional studies. MIPS-9922, 10 potently inhibited ADP-induced washed platelet aggregation. It also inhibited integrin αIIbß3 activation and αIIbß3 dependent platelet adhesion to immobilized vWF under high shear. It prevented arterial thrombus formation in the in vivo electrolytic mouse model of thrombosis without inducing prolonged bleeding or excess blood loss.

Class II but Not Second Class-Prospects for the Development of Class II PI3K Inhibitors.

The Class II PI3 kinases are emerging from the shadows of their Class I cousins. The data emerging from PIK3C2 genetic modification studies and from siRNA knockdown suggest important roles in physiology and pathology. With some well-studied Class I isoform inhibitors showing strong Class II activity and a wealth of crystallographic information available, the structural similarity of these isoforms to Class I provides both the opportunity and the challenge in design of selective pharmacological inhibitors.

L-Aminoacyl-triazine derivatives are isoform-selective PI3Kß inhibitors that target non-conserved Asp862 of PI3Kß

A series of aminoacyl-triazine derivatives based upon the pan-PI3K inhibitor ZSTK474 were identified as potent and isoform selective inhibitors of PI3Kß. The compounds showed selectivity based upon stereochemistry with L-amino acyl derivatives preferring PI3Kß while their D-congeners favoured PI3Kδ. The mechanistic basis of this inhibition was studied using site-directed mutants. One Asp residue, D862 was identified as a critical participant in binding to the PI3Kß-selective inhibitors distinguishing this class from other reported PI3Kß-selective inhibitors. The compounds show strong inhibition of cellular Akt phosphorylation and growth of PTEN-deficient MD-MBA-468 cells.

Mechanisms of PI3Kß-selective inhibition revealed by reciprocal mutagenesis.

The p110ß isoform of PI3 kinase (PI3Kß) has been implicated in pathological disorders such as thrombosis and cancer and a number of PI3Kß-selective inhibitors have recently progressed into clinical studies. Although crystallography studies identify a binding site conformation favored by the inhibitors, no specific interaction explains the observed selectivity. Using site-directed mutagenesis we have identified a specific tyrosine residue of the binding site Y778 that dictates the ability of the PI3Kß isoform to bind these inhibitors. When mutated to isoleucine, PI3Kß has reduced ability to present a specific cryptic binding site into which a range of reported PI3Kß inhibitors can bind, and conversely when tyrosine is introduced into the same position in PI3Kα, the same inhibitors gain potency. The results provide a cogent explanation for the selectivity profiles displayed by these PI3K inhibitors and maybe others as well.

Regioselective synthesis of 5- and 6-methoxybenzimidazole-1,3,5-triazines as inhibitors of phosphoinositide 3-kinase.

Phosphoinositide 3-kinases (PI3K) hold significant therapeutic potential as novel targets for the treatment of cancer. ZSTK474 (4a) is a potent, pan-PI3K inhibitor currently under clinical evaluation for the treatment of cancer. Structural studies have shown that derivatisation at the 5- or 6-position of the benzimidazole ring may influence potency and isoform selectivity. However, synthesis of these derivatives by the traditional route results in a mixture of the two regioisomers. We have developed a straightforward regioselective synthesis that gave convenient access to 5- and 6-methoxysubstituted benzimidazole derivatives of ZSTK474. While 5-methoxy substitution abolished activity at all isoforms, the 6-methoxy substitution is consistently 10-fold more potent. This synthesis will allow convenient access to further 6-position derivatives, thus allowing the full scope of the structure-activity relationships of ZSTK474 to be probed.

Definition of the binding mode of a new class of phosphoinositide 3-kinase α-selective inhibitors using in vitro mutagenesis of non-conserved amino acids and kinetic analysis.

The binding mechanism of a new class of lipid-competitive, ATP non-competitive, p110α isoform-selective PI3K (phosphoinositide 3-kinase) inhibitors has been elucidated. Using the novel technique of isoform reciprocal mutagenesis of non-conserved amino acids in the p110α and p110ß isoforms, we have identified three unique binding mechanisms for the p110α-selective inhibitors PIK-75, A-66S and J-32. Each of the inhibitor's p110α-isoform-selective binding was found to be due to interactions with different amino acids within p110. The PIK-75 interaction bound the non-conserved region 2 amino acid p110α Ser(773), A-66S bound the region 1 non-conserved amino acid p110α Gln(859), and J-32 binding had an indirect interaction with Lys(776) and Ile(771). The isoform reciprocal mutagenesis technique is shown to be an important analytical tool for the rational design of isoform-selective inhibitors.

Synthesis and Pharmacological Evaluation of 4-Iminothiazolidinones for Inhibition of PI3 Kinase.

The thiazolidinedione, compound 1, has previously shown pan-inhibition of the phosphoinositide 3-kinase (PI3K) class I isoforms. We hypothesized the derivatization of the thiazolidinedione core of compound 1 could introduce isoform selectivity. We report the synthesis, characterization, and inhibitory activity of a novel series of 4-iminothiazolidin-2-ones for inhibition of the class I PI3K isoforms. Their synthesis was successfully achieved by multiple pathways described in this paper. Initial in vitro data of 28 analogues demonstrated poor inhibition of all class I PI3K isoforms. However, we identified an alternate target, the phosphodiesterases, and present preliminary screening results showing improved inhibitory activity.

Thiophene inhibitors of PDE4: crystal structures show a second binding mode at the catalytic domain of PDE4D2.

PDE4 inhibitors have been identified as therapeutic targets for a variety of conditions, particularly inflammatory diseases. We have serendipitously identified a novel class of phosphodiesterase 4 (PDE4) inhibitor during a study to discover antagonists of the parathyroid hormone receptor. X-ray crystallographic studies of PDE4D2 complexed to four potent inhibitors reveal the atomic details of how they inhibit the enzyme and a notable contrast to another recently reported thiophene-based inhibitor.

Isoform-selective inhibition of phosphoinositide 3-kinase: identification of a new region of nonconserved amino acids critical for p110α inhibition.

The combination of molecular modeling and X-ray crystallography has failed to yield a consensus model of the mechanism for selective binding of inhibitors to the phosphoinositide 3-kinase (PI3K) p110 α-isoform. Here we have used kinetic analysis to determine that the p110α-selective inhibitor 2-methyl-5-nitro-2-[(6-bromoimidazo[1,2-α]pyridin-3-yl)methylene]-1-methylhydrazide-benzenesulfonic acid (PIK-75) is a competitive inhibitor with respect to a substrate, phosphatidylinositol (PI) in contrast to most other PI3K inhibitors, which bind at or near the ATP site. Using sequence analysis and the existing crystal structures of inhibitor complexes with the p110γ and -δ isoforms, we have identified a new region of nonconserved amino acids (region 2) that was postulated to be involved in PIK-75 p110α selectivity. Analysis of region 2, using in vitro mutation of identified nonconserved amino acids to alanine, showed that Ser773 was a critical amino acid involved in PIK-75 binding, with an 8-fold-increase in the IC(50) compared with wild-type. Kinetic analysis showed that, with respect to PI, the PIK-75 K(i) for the isoform mutant S773D increased 64-fold compared with wild-type enzyme. In addition, a nonconserved amino acid, His855, from the previously identified region 1 of nonconserved amino acids, was found to be involved in PIK-75 binding. These results show that these two regions of nonconserved amino acids that are close to the substrate binding site could be targeted to produce p110α isoform-selective inhibitors.

Reduction of doxorubicin resistance in P-glycoprotein overexpressing cells by hybrid cell-penetrating and drug-binding peptide.

Drug efflux by the membrane transporter P-glycoprotein (P-gp) plays a key role in multidrug resistance (MDR). In order to bypass P-gp, thus overcoming MDR, a hybrid peptide comprising a cell penetrating peptide (Tat) and a drug binding motif (DBM) has been developed to noncovalently bind and deliver doxorubicin (Dox) into MDR cells. The uptake of Dox into the leukemia cell line K562 and its P-gp overexpressing subline KD30 increased in the presence of DBM-Tat peptide. Confocal microscopy indicated that DBM-Tat associated Dox was directed to a perinuclear area of KD30 cells, while this was not observed in parent K562 cells. When KD30 cells were pretreated with the endosomotropic agent chloroquine (CLQ), peptide associated Dox redistributed into the cytosol, indicating that endocytosis was the predominant uptake route. Altered drug uptake kinetics observed by cellular accumulation assay also supported an endocytic uptake. In the presence of CLQ, DBM-Tat was able to enhance the cytotoxicity of Dox by 68.4% at 5 microM peptide concentration in KD30 cells but there were only minor effects on Dox cytotoxicity in K562 cells even in the presence of CLQ. Thus, combining Dox with DBM-Tat reduces P-gp mediated drug efflux, without a requirement for drug modification or inhibiting P-gp function.