Prediction of ovarian cancer prognosis using statistical radiomic features of ultrasound images.

Ovarian cancer is the deadliest gynecologic malignancy worldwide. Ultrasound is the most useful non-invasive test for preoperative diagnosis of ovarian cancer. In this study, by leveraging multiple ultrasound images from the same patient to generate personalized, informative statistical radiomic features, we aimed to develop improved ultrasound image-based prognostic models for ovarian cancer. A total of 2,057 ultrasound images from 514 ovarian cancer patients, including 355 patients with epithelial ovarian cancer, from two hospitals in China were collected for this study. The models were constructed using our recently developed Frequency Appearance in Multiple Univariate pre-Screening (FAMUS) feature selection algorithm and Cox proportional hazards model. The models showed high predictive performance for overall survival (OS) and recurrence-free survival (RFS) in both epithelial and nonepithelial ovarian cancer, with concordance indices (C-index) ranging from 0.773 to 0.794. Radiomic scores predicted 2-year OS and RFS risk groups with significant survival differences (log-rank test, P<1.0e-4 for both validation cohorts). OS and RFS hazard ratios between low- and high-risk groups were 15.994 and 30.692 (internal cohort) and 19.339 and 19.760 (external cohort), respectively. The improved performance of these newly developed prognostic models was mainly attributed to the use of multiple preoperative ultrasound images from the same patient to generate statistical radiomic features, rather than simply using the largest tumor ROI among them. The models also revealed that the roundness of tumor lesion shape was positively correlated with prognosis for ovarian cancer. In summary, the newly developed prognostic models based on statistical radiomic features from ultrasound images were highly predictive of the risk of cancer-related death and possible recurrence not only for patients with epithelial ovarian cancer but also for those with nonepithelial ovarian cancer. They thereby provide reliable, non-invasive markers for individualized prognosis evaluation and clinical decision-making for patients with ovarian cancer.

Structure of the type 38 Streptococcus pneumoniae capsular polysaccharide.

Streptococcus pneumoniae is one of the globally important encapsulated human pathogens and more than 100 different serotypes have been identified. Despite very extensive genetic and immune-serological studies, the capsular polysaccharide repeating unit structure of several serotypes has not been determined yet, including the type 38 (type 38 in Danish nomenclature; type 71 in US nomenclature). Physicochemical data revealed that type 38 polysaccharide is composed of a pentasaccharide repeat unit →3)-[ß-D-Galf(1 â†’ 2)]-ß-D-GalpA6(L-Ser)-(1 â†’ 3)-α-D-GlcpNAc-(1 â†’ 3)-α-D-Sugp-(1 â†’ 4)-α-D-Galp(2OAc)-(1 â†’ . The polysaccharide is O-acetylated at position C2 of the α-Gal residue at approximately (68-87 %) of the repeat units.

Resistance exercise preconditioning prevents disuse muscle atrophy by inhibiting apoptosis and protein degradation via SESN2 in C57BL/6J mice.

AIM: To compare the effects of different exercise preconditioning in the context of skeletal muscle atrophy and to investigate the potential involvement of Sestrin2 (SESN2), a stress-inducible protein that can be regulated by exercise, in exercise preconditioning on preventing disuse muscle atrophy. METHODS: Eight-week-old male C57BL/6J mice were randomly assigned to sedentary groups (SD), aerobic exercise groups (AE), resistance exercise groups (RE), and combined exercise groups (CE) with or without 7 days of immobilization. The duration of the exercise intervention was 10 weeks. The effects of different exercise preconditioning to prevent muscle atrophy were analyzed by evaluating skeletal muscle function and mass. Additionally, to investigate the potential underlying mechanism of exercise-induced protection of skeletal muscle, wild-type and SESN2--/-- mice were randomly divided into sedentary group and resistance exercise preconditioning group. C2C12 cells were treated with SESN2 adenoviruses and MK2206 (an AKT inhibitor) for 48 h to elucidate the underlined mechanism. RESULTS: RE was more effective in preserving skeletal muscle function, muscle mass and maintaining skeletal muscle protein homeostasis than AE and CE under immobilized condition. Importantly, exercise performance, muscle mass to body weight ratio, and the cross-sectional area of muscle fibers were significantly lower in SESN2-/- mice than wild-type mice after resistance exercise preconditioning. Mechanistically, the absence of SESN2 led to activation of the ubiquitin-proteasome system and induction of apoptosis. In vitro experiments showed that MK2206 treatment mitigated the regulatory effects of overexpression-SESN2 on protein hydrolysis and apoptosis. CONCLUSION: RE was more effective than AE or CE in preventing disuse muscle atrophy. SESN2 mediated the protective effects of resistance exercise preconditioning on skeletal muscle atrophy.

Mollugin ameliorates murine allergic airway inflammation by inhibiting Th2 response and M2 macrophage activation.

Mollugin, isolated from Rubia cordifolia L, is a pharmacological compound with anti-inflammatory activity. This study aimed to investigate whether mollugin protects mice against shrimp tropomyosin (ST)-induced allergic airway inflammation. Mice were sensitized with ST combined with Al(OH)3 administered intraperitoneally (i.p.) once weekly for 3 wk followed by ST challenge for 5 d. Mice were i.p.-administered daily with mollugin for 7 d. Results showed that mollugin attenuated ST-induced infiltration of eosinophils and epithelial mucus secretion in the lung tissues and suppressed lung eosinophil peroxidase activity. Additionally, mollugin lowered the Th2 cytokine, IL-4 and IL-5, production and downregulated the mRNA levels of Il-4, Il-5, Il-13, eotaxin, Ccl-17, Muc5ac, arginase-1, Ym-1, and Fizz-1 in the lung tissues. Network pharmacology was employed to predict core targets, and the molecular docking approach was used to verify the compound targets. The results of the molecular docking study of mollugin into p38 MAPK or poly(ADP-ribose) polymerase 1 (PARP1) binding sites revealed that its mechanism was possibly similar to that of SB203580 (a p38 MAPK inhibitor) or olaparib (a PARP1 inhibitor). Immunohistochemistry analysis revealed that mollugin mitigated ST-induced elevation of arginase-1 expression and macrophage levels in the lungs and bronchoalveolar lavage fluid, respectively. Furthermore, arginase-1 mRNA level and phosphorylation of p38 MAPK were inhibited in IL-4-stimulated peritoneal macrophages. In ST-stimulated mouse primary splenocytes, mollugin notably inhibited IL-4 and IL-5 production and downregulated PARP1 and PAR protein expression. According to our findings, mollugin ameliorated allergic airway inflammation by inhibiting Th2 response and macrophage polarization.

Hyperthermia-sensitive Liposomes Containing Brucea Javanica Oil for Synergistic Photothermal-/Chemo-Therapy in Breast Cancer Treatment.

INTRODUCTION: High mortality and limited therapeutic efficacy of clinical treatment make breast cancer a stubborn disease in women. The hypovascular issue is the main challenge needed to be overcome in breast cancer treatment. METHODS: For this purpose, hyperthermia-sensitive liposomes containing indocyanine green (ICG) and brucea javanica oil (BJO) (LP(BJO/ICG)) were constructed for near-infrared (NIR) laser-induced photothermal- /chemo-antitumor therapy. ICG, an FDA-approved photothermal agent, was employed in this study to perform photothermal therapy (PTT) effect as well as relieve hypovascular conditions in breast cancer tissue. RESULTS: BJO triggered release from the hyperthermia-sensitive LP (BJO/ICG) due to disassembly of liposomes under the PTT effect caused by ICG under NIR laser irradiation. It was found that mice in LP (BJO/ICG) group showed the slowest tumor growth under NIR laser irradiation, illustrating the strongest antitumor effect among all groups. CONCLUSION: This responsive-release drug delivery platform can be a promising candidate for the treatment of breast cancer.

Preferential binding of DAP-PGs by major peptidoglycan recognition proteins found in cell-free hemolymph of Manduca sexta.

Peptidoglycan recognition proteins (PGRPs) detect invading bacteria to trigger or modulate immune responses in insects. While these roles are established in Drosophila, functional studies are not yet achieved at the PGRP family level in other insects. To attain this goal, we selected Manduca sexta PGRP12 and five of the nine secreted PGRPs for recombinant expression and biochemical characterization. We cloned PGRP2-5, 12 and 13 cDNAs, produced the proteins in full (PGRP2-5, 13) or in part (PGRP3s, 12e, 13N, 13C) in Sf9 cells, and tested their bindings of two muramyl pentapeptides by surface plasmon resonance, two soluble peptidoglycans by competitive ELISA, and four insoluble peptidoglycans and eight whole bacteria by a pull-down assay. Preferential binding of meso-diaminopimelic acid-peptidoglycans (DAP-PGs) was observed in all the proteins containing a peptidoglycan binding domain and, since PGRP6, 7 and 9 proteins were hardly detected in cell-free hemolymph, the reportoire of PGRPs (including PGRP1 published previously) in M. sexta hemolymph is likely adapted to mainly detect Gram-negative bacteria and certain Gram-positive bacteria with DAP-PGs located on their surface. After incubation with plasma from naïve larvae, PGRP2, 3f, 4, 5, 13f and 13N considerably stimulated prophenoloxidase activation in the absence of a bacterial elicitor. PGRP3s and 12e had much smaller effects. Inclusion of the full-length PGRPs and their regions in the plasma also led to proHP8 activation, supporting their connections to the Toll pathway, since HP8 is a Spӓtzle-1 processing enzyme in M. sexta. Together, these findings raised concerns on the common belief that the Toll-pathway is specific for Gram-positive bacteria in insects.

Deletion of the miR-144/451 cluster aggravates lethal sepsis-induced lung epithelial oxidative stress and apoptosis.

Background: Sepsis is associated with a high mortality rate. A major cause of death in sepsis patients is respiratory failure, which is characterized by oxidative injury, epithelial apoptosis, and increased lung permeability. MicroRNAs (miRs) are important regulators of sepsis progression. Methods: This study aimed to explore the role of miR-144/451 in sepsis in mice. Experimental sepsis was induced in C57BL/6 mice by cecal ligation and puncture (CLP). Results: CLP significantly induced systemic inflammation, lung permeability, and lung epithelial apoptosis with downregulated messenger RNA (mRNA) levels of antioxidant enzymes. The miR-144/451 knockout mice had a lower 48-hour survival rate, higher plasma tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) levels, and greater pulmonary permeability compared with wild-type mice after CLP. CLP also markedly increased interstitial hemorrhage, collapsed more alveolar sacs, and increased the number of terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)-positive and Bcl-2-associated X (Bax)-positive cells in miR-144/451 knockout lung tissues, with elevated mRNA levels of Bax and reduced activities of catalase (Cat), glutathione peroxidase 1(Gpx1). MiR-451 negatively regulated 14-3-3ζ expression evidenced in miR-144/451 knockout lungs and the A549 cell line. In lipopolysaccharide (LPS)-induced A549 cells, miR-451 overexpression remarkably suppressed the production of reactive oxygen species, inhibited cell apoptosis, and enhanced levels of FoxO3 protein and related enzymes. Conclusions: Deletion of the miR-144/451 cluster aggravated sepsis-induced oxidative injury of lung epithelial cells.

Heparan Sulfate Proteoglycans as Attachment Factor for SARS-CoV-2.

Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) is causing an unprecedented global pandemic demanding the urgent development of therapeutic strategies. Microarray binding experiments, using an extensive heparan sulfate (HS) oligosaccharide library, showed that the receptor binding domain (RBD) of the spike of SARS-CoV-2 can bind HS in a length- and sequence-dependent manner. A hexasaccharide composed of IdoA2S-GlcNS6S repeating units was identified as the minimal binding epitope. Surface plasmon resonance showed the SARS-CoV-2 spike protein binds with a much higher affinity to heparin (K D = 55 nM) compared to the RBD (K D = 1 µM) alone. It was also found that heparin does not interfere in angiotensin-converting enzyme 2 (ACE2) binding or proteolytic processing of the spike. However, exogenous administered heparin or a highly sulfated HS oligosaccharide inhibited RBD binding to cells. Furthermore, an enzymatic removal of HS proteoglycan from physiological relevant tissue resulted in a loss of RBD binding. The data support a model in which HS functions as the point of initial attachment allowing the virus to travel through the glycocalyx by low-affinity high-avidity interactions to reach the cell membrane, where it can engage with ACE2 for cell entry. Microarray binding experiments showed that ACE2 and HS can simultaneously engage with the RBD, and it is likely no dissociation between HS and RBD is required for binding to ACE2. The results highlight the potential of using HS oligosaccharides as a starting material for therapeutic agent development.

Huangkui Capsule Attenuates Lipopolysaccharide-Induced Acute Lung Injury and Macrophage Activation by Suppressing Inflammation and Oxidative Stress in Mice.

Background: Huangkui capsule (HKC) comprises the total flavonoid extract of flowers of Abelmoschus manihot (L.) Medicus. This study aimed to explore the effects of HKC on lipopolysaccharide- (LPS-) induced acute lung injury (ALI) in mice and LPS-stimulated RAW 264.7 cells. Methods: Enzyme-linked immunosorbent assay, histopathology, spectrophotometry, and quantitative real-time polymerase chain reaction were used for the assessments. Statistical analysis was performed using a one-way analysis of variance. Results: LPS significantly increased lung inflammation, neutrophil infiltration, and oxidative stress and downregulated lung miR-451 expression. Treatment with HKC dramatically, reduced the total cell count in the bronchoalveolar lavage fluid (BALF), and inhibited myeloperoxidase activity in the lung tissues 24 h after LPS challenge. Histopathological analysis demonstrated that HKC attenuated LPS-induced tissue oedema and neutrophil infiltration in the lung tissues. Additionally, the concentrations of tumour necrosis factor- (TNF-) α and interleukin- (IL-) 6 in BALF and IL-6 in the plasma reduced after HKC administration. Moreover, HKC could enhance glutathione peroxidase and catalase activities and upregulate the expression of miR-451 in the lung tissues. In vitro experiments revealed that HKC inhibited the production of nitric oxide, TNF-α, and IL-6 in LPS-induced RAW 264.7 cells and mouse primary peritoneal macrophages. Additionally, HKC downregulated LPS-induced transcription of TNF-α and IL-6 in RAW 264.7 cells. Conclusions: These findings suggest that HKC has anti-inflammatory and antioxidative effects that may protect mice against LPS-induced ALI and macrophage activation.

Heparan sulfate proteoglycans as attachment factor for SARS-CoV-2.

Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) is causing an unprecedented global pandemic demanding the urgent development of therapeutic strategies. Microarray binding experiments using an extensive heparan sulfate (HS) oligosaccharide library showed that the receptor binding domain (RBD) of the spike of SARS-CoV-2 can bind HS in a length- and sequence-dependent manner. Hexa- and octa-saccharides composed of IdoA2S-GlcNS6S repeating units were identified as optimal ligands. Surface plasma resonance (SPR) showed the SARS-CoV-2 spike protein binds with much higher affinity to heparin (KD = 55 nM) compared to the RBD (KD = 1 uM) alone. We also found that heparin does not interfere in angiotensin-converting enzyme 2 (ACE2) binding or proteolytic processing of the spike. Our data supports a model in which HS functions as the point of initial attachment for SARS-CoV-2 infection. Tissue staining studies using biologically relevant tissues indicate that heparan sulfate proteoglycan (HSPG) is a critical attachment factor for the virus. Collectively, our results highlight the potential of using HS oligosaccharides as a therapeutic agent by inhibiting SARS-CoV-2 binding to target cells.

Discovery of Ebselen as an Inhibitor of 6PGD for Suppressing Tumor Growth.

INTRODUCTION: The 6-phosphogluconate dehydrogenase (6PGD) was upregulated in many solid cancers and plays an important role in tumorigenesis. In the present study, we want to discover an old drug as an inhibitor of 6PGD for suppressing tumor growth. METHODS: We determined the expression of 6PGD in cancer tissues using Gene Expression Omnibus (GEO) profiles and explored the importance of 6PGD expression in cancer progression by using Kaplan-Meier Plotter. We identified Ebselen as a 6PGD inhibitor by using 6PGD in vitro enzyme activity assay. Cell viability, cell proliferation, tumor growth and cell metabolism assay were used to explore the role of 6PGD and its inhibitor in cancer cells. RESULTS: We found that the expression of 6PGD was upregulated in different cancer tissues and it can promote tumorigenesis. Here, we analyzed our 6PGD inhibitor screening data again and found an old drug Ebselen, which blocks cancer cell proliferation and tumor growth by inhibiting 6PGD enzyme activity, while knocking down 6PGD would partially abolish the inhibition of Ebselen on cell proliferation and cell metabolism. CONCLUSION: Our results suggested that the conventional drug Ebselen could serve as a novel inhibitor of 6PGD for suppressing cancer growth by inhibiting 6PGD enzyme activity.

Targeting G6PD reverses paclitaxel resistance in ovarian cancer by suppressing GSTP1.

Ovarian cancer is one of the leading causes of mortality in women worldwide. Currently, paclitaxel is one of the most effective chemotherapies. However, resistance to paclitaxel is a major cause of therapy failure and the precise mechanism of paclitaxel resistance remains unclear. In this study, we demonstrated that the oxidative pentose phosphate pathway (PPP) enzyme glucose-6-phosphate dehydrogenase (G6PD) promotes paclitaxel resistance. We showed that G6PD expression was higher in paclitaxel-resistant cancer cells than in their paclitaxel-sensitive counterparts. Furthermore, we demonstrated that suppressing G6PD using shRNA, or an inhibitor, either as single agents or in combination, sensitized paclitaxel-resistant cancer cells to paclitaxel treatment and thereby improving the therapeutic efficacy of paclitaxel. Interestingly, we found that the upregulation of G6PD in paclitaxel-resistant cells was due to the decreased expression of protein arginine methyltransferase 6 (PRMT6), which targets the promoter of G6PD. We further identified that G6PD promotes paclitaxel resistance by regulating the expression of glutathione S-transferase P1 (GSTP1), which confers resistance to chemotherapy by detoxifying several anticancer drugs. Taken together, our results suggest that G6PD is a novel potential target to overcome paclitaxel resistance.

The three-dimensional structure and recognition mechanism of Manduca sexta peptidoglycan recognition protein-1.

Peptidoglycan recognition proteins (PGRPs) recognize bacteria through their unique cell wall constituent, peptidoglycans (PGs). PGRPs are conserved from insects to mammals and all function in antibacterial defense. In the tobacco hornworm Manduca sexta, PGRP1 and microbe binding protein (MBP) interact with PGs and hemolymph protease-14 precursor (proHP14) to yield active HP14. HP14 triggers a serine protease network that produces active phenoloxidase (PO), Spätzle, and other cytokines to stimulate immune responses. PGRP1 binds preferentially to diaminopimelic acid (DAP)-PGs of Gram-negative bacteria and Gram-positive Bacillus and Clostridium species than Lys-PGs of other Gram-positive bacteria. In this study, we synthesized DAP- and Lys-muramyl pentapeptide (MPP) and monitored their associations with M. sexta PGRP1 by surface plasmon resonance. The Kd values (0.57 µM for DAP-MPP and 45.6 µM for Lys-MPP) agree with the differential recognition of DAP- and Lys-PGs. To reveal its structural basis, we produced the PGRP1 in insect cells and determined its structure at a resolution of 2.1 Å. The protein adopts a fold similar to those from other PGRPs with a classical L-shaped PG-binding groove. A unique loop lining the shallow groove suggests a different ligand-binding mechanism. In summary, this study provided new insights into the PG recognition by PGRPs, a critical first step that initiates the serine protease cascade.

Synthesis of a Glycosylphosphatidylinositol Anchor Derived from Leishmania donovani That Can Be Functionalized by Cu-Catalyzed Azide-Alkyne Cycloadditions.

A flexible assembly strategy has been developed for the synthesis of Leishmania donovani GPI anchors that bear a clickable alkyne tag. This strategy is based on the use of the 2-naphthylmethyl (Nap) ethers and levulinoyl (Lev) ester for permanent protection of hydroxyls. Removal of seven Nap ethers by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone made it possible to prepare GPIs having an alkyne functionality that could be modified by Cu(I)-catalyzed [3 + 2] cycloadditions to install tags for imaging studies.

Heparan Sulfate Microarray Reveals That Heparan Sulfate-Protein Binding Exhibits Different Ligand Requirements.

Heparan sulfates (HS) are linear sulfated polysaccharides that modulate a wide range of physiological and disease-processes. Variations in HS epimerization and sulfation provide enormous structural diversity, which is believed to underpin protein binding and regulatory properties. The ligand requirements of HS-binding proteins have, however, been defined in only a few cases. We describe here a synthetic methodology that can rapidly provide a library of well-defined HS oligosaccharides. It is based on the use of modular disaccharides to assemble several selectively protected tetrasaccharides that were subjected to selective chemical modifications such as regioselective O- and N-sulfation and selective de-sulfation. A number of the resulting compounds were subjected to enzymatic modifications by 3-O-sulfotransferases-1 (3-OST1) to provide 3-O-sulfated derivatives. The various approaches for diversification allowed one tetrasaccharide to be converted into 12 differently sulfated derivatives. By employing tetrasaccharides with different backbone compositions, a library of 47 HS-oligosaccharides was prepared and the resulting compounds were used to construct a HS microarray. The ligand requirements of a number of HS-binding proteins including fibroblast growth factor 2 (FGF-2), and the chemokines CCL2, CCL5, CCL7, CCL13, CXCL8, and CXCL10 were examined using the array. Although all proteins recognized multiple compounds, they exhibited clear differences in structure-binding characteristics. The HS microarray data guided the selection of compounds that could interfere in biological processes such as cell proliferation. Although the library does not cover the entire chemical space of HS-tetrasaccharides, the binding data support a notion that changes in cell surface HS composition can modulate protein function.

Integrated Approach to Identify Heparan Sulfate Ligand Requirements of Robo1.

An integrated methodology is described to establish ligand requirements for heparan sulfate (HS) binding proteins based on a workflow in which HS octasaccharides are produced by partial enzymatic degradation of natural HS followed by size exclusion purification, affinity enrichment using an immobilized HS-binding protein of interest, putative structure determination of isolated compounds by a hydrophilic interaction chromatography-high-resolution mass spectrometry platform, and chemical synthesis of well-defined HS oligosaccharides for structure-activity relationship studies. The methodology was used to establish the ligand requirements of human Roundabout receptor 1 (Robo1), which is involved in a number of developmental processes. Mass spectrometric analysis of the starting octasaccharide mixture and the Robo1-bound fraction indicated that Robo1 has a preference for a specific set of structures. Further analysis was performed by sequential permethylation, desulfation, and pertrideuteroacetylation followed by online separation and structural analysis by MS/MS. Sequences of tetrasaccharides could be deduced from the data, and by combining the compositional and sequence data, a putative octasaccharide ligand could be proposed (GlA-GlcNS6S-IdoA-GlcNS-IdoA2S-GlcNS6S-IdoA-GlcNAc6S). A modular synthetic approach was employed to prepare the target compound, and binding studies by surface plasmon resonance (SPR) confirmed it to be a high affinity ligand for Robo1. Further studies with a number of tetrasaccharides confirmed that sulfate esters at C-6 are critical for binding, whereas such functionalities at C-2 substantially reduce binding. High affinity ligands were able to reverse a reduction in endothelial cell migration induced by Slit2-Robo1 signaling.

Label-Free Detection of Glycan-Protein Interactions for Array Development by Surface-Enhanced Raman Spectroscopy (SERS).

A glyco-array platform has been developed, in which glycans are attached to plasmonic nanoparticles through strain-promoted azide-alkyne cycloaddition. Glycan-protein binding events can then be detected in a label-free manner employing surface-enhanced Raman spectroscopy (SERS). As proof of concept, we have analyzed the binding of Gal1, Gal3, and influenza hemagglutinins (HAs) to various glycans and demonstrated that binding partners can be identified with high confidence. The attraction of SERS for optical sensing is that it can provide unique spectral signatures for glycan-protein complexes, confirm identity through statistical validation, and minimizes false positive results common to indirect methods. Furthermore, SERS is very sensitive and has multiplexing capabilities thereby allowing the simultaneous detection of multiple analytes.

Controlled Multi-functionalization Facilitates Targeted Delivery of Nanoparticles to Cancer Cells.

A major objective of nanomedicine is to combine in a controlled manner multiple functional entities into a single nanoscale device to target particles with great spatial precision, thereby increasing the selectivity and potency of therapeutic drugs. A multifunctional nanoparticle is described for controlled conjugation of a cytotoxic drug, a cancer cell targeting ligand, and an imaging moiety. The approach is based on the chemical synthesis of polyethylene glycol that at one end is modified by a thioctic acid for controlled attachment to a gold core. The other end of the PEG polymers is modified by a hydrazine, amine, or dibenzocyclooctynol moiety for conjugation with functional entities having a ketone, activated ester, or azide moiety, respectively. The conjugation approach allowed the controlled attachment of doxorubicin through an acid-labile hydrazone linkage, an Alexa Fluor dye through an amide bond, and a glycan-based ligand for the cell surface receptor CD22 of B-cells using strain promoted azide-alkyne cycloaddition. The incorporation of the ligand for CD22 led to rapid entry of the nanoparticle by receptor-mediated endocytosis. Covalent attachment of doxorubicin via hydrazone linkage caused pH-responsive intracellular release of doxorubicin and significantly enhanced the cytotoxicity of nanoparticles. A remarkable 60-fold enhancement in cytotoxicity of CD22 (+) lymphoma cells was observed compared to non- targeted nanoparticles.

Preparation of well-defined antibody-drug conjugates through glycan remodeling and strain-promoted azide-alkyne cycloadditions.

Antibody-drug conjugates hold considerable promise as anticancer agents, however, producing them remains a challenge and there is a need for mild, broadly applicable, site-specific conjugation methods that yield homogenous products. It was envisaged that enzymatic remodeling of the oligosaccharides of an antibody would enable the introduction of reactive groups that can be exploited for the site-specific attachment of cytotoxic drugs. This is based on the observation that glycosyltransferases often tolerate chemical modifications in their sugar nucleotide substrates, thus allowing the installation of reactive functionalities. An azide was incorporated because this functional group is virtually absent in biological systems and can be reacted by strain-promoted alkyne-azide cycloaddition. This method, which does not require genetic engineering, was used to produce an anti-CD22 antibody modified with doxorubicin to selectively target and kill lymphoma cells.