Panoramic Tissue Examination That Integrates 3-Dimensional Pathology Imaging and Gene Mutation: Potential Utility in Non-Small Cell Lung Cancer.

Novel therapeutics have significantly improved the survival and quality of life of patients with malignancies in this century. Versatile precision diagnostic data were used to formulate personalized therapeutic strategies for patients. However, the cost of extensive information depends on the consumption of the specimen, raising the challenges of effective specimen utilization, particularly in small biopsies. In this study, we proposed a tissue-processing cascaded protocol that obtains 3-dimensional (3D) protein expression spatial distribution and mutation analysis from an identical specimen. In order to reuse the thick section tissue evaluated after the 3D pathology technique, we designed a novel high-flatness agarose-embedded method that could improve tissue utilization rate by 1.52 fold, whereas it reduced the tissue-processing time by 80% compared with the traditional paraffin-embedding method. In animal studies, we demonstrated that the protocol would not affect the results of DNA mutation analysis. Furthermore, we explored the utility of this approach in non-small cell lung cancer because it is a compelling application for this innovation. We used 35 cases including 7 cases of biopsy specimens of non-small cell lung cancer to simulate future clinical application. The cascaded protocol consumed 150-µm thickness of formalin-fixed, paraffin-embedded specimens, providing 3D histologic and immunohistochemical information approximately 38 times that of the current paraffin-embedding protocol, and 3 rounds of DNA mutation analysis, offering both essential guidance for routine diagnostic evaluation and advanced information for precision medicine. Our designed integrated workflow provides an alternative way for pathological examination and paves the way for multidimensional tumor tissue assessment.

A domain knowledge enhanced yield based deep learning classifier identifies perineural invasion in oral cavity squamous cell carcinoma.

Background: Perineural invasion (PNI), a form of local invasion defined as the ability of cancer cells to invade in, around, and through nerves, has a negative prognostic impact in oral cavity squamous cell carcinoma (OCSCC). Unfortunately, the diagnosis of PNI suffers from a significant degree of intra- and interobserver variability. The aim of this pilot study was to develop a deep learning-based human-enhanced tool, termed domain knowledge enhanced yield (Domain-KEY) algorithm, for identifying PNI in digital slides. Methods: Hematoxylin and eosin (H&E)-stained whole-slide images (WSIs, n = 85) were obtained from 80 patients with OCSCC. The model structure consisted of two parts to simulate human decision-making skills in diagnostic pathology. To this aim, two semantic segmentation models were constructed (i.e., identification of nerve fibers followed by the diagnosis of PNI). The inferred results were subsequently subjected to post-processing of generated decision rules for diagnostic labeling. Ten H&E-stained WSIs not previously used in the study were read and labeled by the Domain-KEY algorithm. Thereafter, labeling correctness was visually inspected by two independent pathologists. Results: The Domain-KEY algorithm was found to outperform the ResnetV2_50 classifier for the detection of PNI (diagnostic accuracy: 89.01% and 61.94%, respectively). On analyzing WSIs, the algorithm achieved a mean diagnostic accuracy as high as 97.50% versus traditional pathology. The observed accuracy in a validation dataset of 25 WSIs obtained from seven patients with oropharyngeal (cancer of the tongue base, n = 1; tonsil cancer, n = 1; soft palate cancer, n = 1) and hypopharyngeal (cancer of posterior wall, n = 2; pyriform sinus cancer, n = 2) malignancies was 96%. Notably, the algorithm was successfully applied in the analysis of WSIs to shorten the time required to reach a diagnosis. The addition of the hybrid intelligence model decreased the mean time required to reach a diagnosis by 15.0% and 23.7% for the first and second pathologists, respectively. On analyzing digital slides, the tool was effective in supporting human diagnostic thinking. Conclusions: The Domain-KEY algorithm successfully mimicked human decision-making skills and supported expert pathologists in the routine diagnosis of PNI.

Rapid Histological Assessment of Prostate Specimens in the Three-dimensional Space by Hydrophilic Tissue Clearing and Confocal Microscopy.

Microscopic examination of biopsied and resected prostatic specimens is the mainstay in the diagnosis of prostate cancer. However, conventional analysis of hematoxylin and eosin (H&E)-stained tissue is time-consuming and offers limited two-dimensional (2D) information. In the current study, we devised a method-termed Prostate Rapid Optical examination for cancer STATus (proSTAT)-for rapid screening of prostate cancer using high-resolution 2D and three-dimensional (3D) confocal images obtained after hydrophilic tissue clearing of 100-µm-thick tissue slices. The results of the proSTAT method were compared with those of traditional H&E stains for the analysis of cores (n=15) obtained from radical prostatectomy specimens (n=5). Gland lumen formation, consistent with Gleason pattern 3, was evident following tracking of multiple optical imaging sections. In addition, 3D rendering allowed visualizing a tubular network of interconnecting branches. Rapid 3D fluorescent labeling of tumor protein p63 accurately distinguished prostate adenocarcinoma from normal tissue and benign lesions. Compared with conventional stains, the 3D spatial and molecular information extracted from proSTAT may significantly increase the amount of available data for pathological assessment of prostate specimens. Our approach is amenable to automation and-subject to independent validation-can find a wide spectrum of clinical and research applications.

Heparan sulfate targeting strategy for enhancing liposomal drug accumulation and facilitating deep distribution in tumors.

Nanoparticles (NPs), such as liposomes, effectively evade the severe toxicity of unexpected accumulation and passively shuttle drugs into tumor tissues by enhanced permeability and retention. In the case of non-small cell lung cancer and pancreatic ductal adenocarcinoma, cancer-associated fibroblasts promote the aggregation of a gel-like extracellular matrix that forms a physical barrier in the desmoplastic stroma of the tumor. These stroma are composed of protein networks and glycosaminoglycans (GAGs) that greatly compromise tumor-penetrating performance, leading to insufficient extravasation and tissue penetration of NPs. Moreover, the presence of heparan sulfate (HS) and related proteoglycans on the cell surface and tumor extracellular matrix may serve as molecular targets for NP-mediated drug delivery. Here, a GAG-binding peptide (GBP) with high affinity for HS and high cell-penetrating activity was used to develop an HS-targeting delivery system. Specifically, liposomal doxorubicin (L-DOX) was modified by post-insertion with the GBP. We show that the in vitro uptake of L-DOX in A549 lung adenocarcinoma cells increased by GBP modification. Cellular uptake of GBP-modified L-DOX (L-DOX-GBP) was diminished in the presence of extracellular HS but not in the presence of other GAGs, indicating that the interaction with HS is critical for the cell surface binding of L-DOX-GBP. The cytotoxicity of doxorubicin positively correlated with the molecular composition of GBP. Moreover, GBP modification improved the in vivo distribution and anticancer efficiency of L-DOX, with enhanced desmoplastic targeting and extensive distribution. Taken together, GBP modification may greatly improve the tissue distribution and delivery efficiency of NPs against HS-abundant desmoplastic stroma-associated neoplasm.

Cell Penetrating Peptide as a High Safety Anti-Inflammation Ingredient for Cosmetic Applications.

Cosmeceutical peptides have become an important topic in recent decades in both academic and industrial fields. Many natural or synthetic peptides with different biological functions including anti-ageing, anti-oxidation, anti-infection and anti-pigmentation have been developed and commercialized. Current cosmeceutical peptides have already satisfied most market demand, remaining: "cargos carrying skin penetrating peptide with high safety" still an un-met need. To this aim, a cell-penetrating peptide, CPPAIF, which efficiently transported cargos into epithelial cells was exanimated. CPPAIF was evaluated with cell model and 3D skin model following OECD guidelines without using animal models. As a highly stable peptide, CPPAIF neither irritated nor sensitized skin, also did not disrupt skin barrier. In addition, such high safety peptide had anti-inflammation activity without allergic effect. Moreover, cargo carrying activity of CPPAIF was assayed using HaCaT cell model and rapid CPPAIF penetration was observed within 30 min. Finally, CPPAIF possessed transepidermal activity in water in oil formulation without disruption of skin barrier. All evidences indicated that CPPAIF was an ideal choice for skin penetrating and its anti-inflammatory activity could improve skin condition, which made CPPAIF suitable and attractive for novel cosmeceutical product development.

Rhamnose Binding Protein as an Anti-Bacterial Agent-Targeting Biofilm of Pseudomonas aeruginosa.

More than 80% of infectious bacteria form biofilm, which is a bacterial cell community surrounded by secreted polysaccharides, proteins and glycolipids. Such bacterial superstructure increases resistance to antimicrobials and host defenses. Thus, to control these biofilm-forming pathogenic bacteria requires antimicrobial agents with novel mechanisms or properties. Pseudomonas aeruginosa, a Gram-negative opportunistic nosocomial pathogen, is a model strain to study biofilm development and correlation between biofilm formation and infection. In this study, a recombinant hemolymph plasma lectin (rHPLOE) cloned from Taiwanese Tachypleus tridentatus was expressed in an Escherichia coli system. This rHPLOE was shown to have the following properties: (1) Binding to P. aeruginosa PA14 biofilm through a unique molecular interaction with rhamnose-containing moieties on bacteria, leading to reduction of extracellular di-rhamnolipid (a biofilm regulator); (2) decreasing downstream quorum sensing factors, and inhibiting biofilm formation; (3) dispersing the mature biofilm of P. aeruginosa PA14 to improve the efficacies of antibiotics; (4) reducing P. aeruginosa PA14 cytotoxicity to human lung epithelial cells in vitro and (5) inhibiting P. aeruginosa PA14 infection of zebrafish embryos in vivo. Taken together, rHPLOE serves as an anti-biofilm agent with a novel mechanism of recognizing rhamnose moieties in lipopolysaccharides, di-rhamnolipid and structural polysaccharides (Psl) in biofilms. Thus rHPLOE links glycan-recognition to novel anti-biofilm strategies against pathogenic bacteria.

Sialylation of vasorin by ST3Gal1 facilitates TGF-ß1-mediated tumor angiogenesis and progression.

ST3Gal1 is a key sialyltransferase which adds α2,3-linked sialic acid to substrates and generates core 1 O-glycan structure. Upregulation of ST3Gal1 has been associated with worse prognosis of breast cancer patients. However, the protein substrates of ST3Gal1 implicated in tumor progression remain elusive. In our study, we demonstrated that ST3GAL1-silencing significantly reduced tumor growth along with a notable decrease in vascularity of MCF7 xenograft tumors. We identified vasorin (VASN) which was shown to bind TGF-ß1, as a potential candidate that links ST3Gal1 to angiogenesis. LC-MS/MS analysis of VASN secreted from MCF7, revealed that more than 80% of its O-glycans are sialyl-3T and disialyl-T. ST3GAL1-silencing or desialylation of VASN by neuraminidase enhanced its binding to TGF-ß1 by 2- to 3-fold and thereby dampening TGF-ß1 signaling and angiogenesis, as indicated by impaired tube formation of HUVECs, suppressed angiogenesis gene expression and reduced activation of Smad2 and Smad3 in HUVEC cells. Examination of 114 fresh primary breast cancer and their adjacent normal tissues showed that the expression levels of ST3Gal1 and TGFB1 were high in tumor part and the expression of two genes was positively correlated. Kaplan Meier survival analysis showed a significantly shorter relapse-free survival for those with lower expression VASN, notably, the combination of low VASN with high ST3GAL1 yielded even higher risk of recurrence (p = 0.025, HR = 2.967, 95% CI = 1.14-7.67). Since TGF-ß1 is known to transcriptionally activate ST3Gal1, our findings illustrated a feedback regulatory loop in which TGF-ß1 upregulates ST3Gal1 to circumvent the negative impact of VASN.

Intrahepatic hepatitis B virus large surface antigen induces hepatocyte hyperploidy via failure of cytokinesis.

Hepatitis B virus (HBV) is an aetiological factor for liver cirrhosis and hepatocellular carcinoma (HCC). Despite current antiviral therapies that successfully reduce the viral load in patients with chronic hepatitis B, persistent hepatitis B surface antigen (HBsAg) remains a risk factor for HCC. To explore whether intrahepatic viral antigens contribute directly to hepatocarcinogenesis, we monitored the mitotic progression of HBV-positive cells. Cytokinesis failure was increased in HBV-positive HepG2.2.15 and 1.3ES2 cells, as well as in HuH-7 cells transfected with a wild-type or X-deficient HBV construct, but not in cells transfected with an HBsAg-deficient construct. We show that expression of viral large surface antigen (LHBS) was sufficient to induce cytokinesis failure of immortalized hepatocytes. Premitotic defects with DNA damage and G2 /M checkpoint attenuation preceded cytokinesis in LHBS-positive cells, and ultimately resulted in hyperploidy. Inhibition of polo-like kinase-1 (Plk1) not only restored the G2 /M checkpoint in these cells, but also suppressed LHBS-mediated in vivo tumourigenesis. Finally, a positive correlation between intrahepatic LHBS expression and hepatocyte hyperploidy was detected in >70% of patients with chronic hepatitis B. We conclude that HBV LHBS provokes hyperploidy by inducing DNA damage and upregulation of Plk1; the former results in atypical chromatin structures, and the latter attenuates the function of the G2 /M DNA damage checkpoint. Our data uncover a mechanism by which genomic integrity of hepatocytes is disrupted by viral LHBS. These findings highlight the role of intrahepatic surface antigen as an oncogenic risk factor in the development of HCC. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Cell Penetrating Peptide Derived from Human Eosinophil Cationic Protein Decreases Airway Allergic Inflammation.

Cell penetrating peptide derived from human eosinophil cationic protein (CPPecp) is a 10-amino-acid peptide containing a core heparan sulfate (HS)-binding motif of human eosinophil cationic protein (ECP). It binds and penetrates bronchial epithelial cells without cytotoxic effects. Here we investigated airway-protective effects of CPPecp in BEAS-2B cell line and mite-induced airway allergic inflammation in BALB/c mice. In BEAS-2B cell, CPPecp decreases ECP-induced eotaxin mRNA expression. CPPecp also decreases eotaxin secretion and p-STAT6 activation induced by ECP, as well as by IL-4. In vivo studies showed CPPecp decreased mite-induced airway inflammation in terms of eosinophil and neutrophil count in broncho-alveolar lavage fluid, peri-bronchiolar and alveolar pathology scores, cytokine production in lung protein extract including interleukin (IL)-5, IL-13, IL-17A/F, eotaxin; and pause enhancement from methacholine stimulation. CPPecp treated groups also showed lower serum mite-specific IgE level. In this study, we have demonstrated the in vitro and in vivo anti-asthma effects of CPPecp.

Heparin-Promoted Cellular Uptake of the Cell-Penetrating Glycosaminoglycan Binding Peptide, GBPECP, Depends on a Single Tryptophan.

A 10-residue, glycosaminoglycan-binding peptide, GBPECP, derived from human eosinophil cationic protein has been recently designated as a potent cell-penetrating peptide. A model system containing peptide, glycan, and lipid was monitored by nuclear magnetic resonance (NMR) spectroscopy to determine the cell-penetrating mechanism. Heparin octasaccharide with dodecylphosphocholine (DPC) lipid micelle was titrated into the GBPECP solution. Our data revealed substantial roles for the charged residues Arg5 and Lys7 in recognizing heparin, whereas Arg3 had less effect. The aromatic residue Trp4 acted as an irreplaceable moiety for membrane insertion, as the replacement of Trp4 with Arg4 abolished cell penetration, although it significantly improved the heparin-binding ability. GBPECP bound either heparin or lipid in the presence or absence of the other ligand indicating that the peptide has two alternative binding sites: Trp4 is responsible for lipid insertion, and Arg5 and Lys7 are for GAG binding. We developed a molecular model showing that the two effects synergistically promote the penetration. The loss of either effect would abolish the penetration. GBPECP has been proven to enter cells through macropinocytosis. The GBPECP treatment inhibited A549 lung cancer cell migration and invasion, implying that the cellular microenvironment would be modulated by GBPECP internalization. The intracellular penetration of GBPECP leading to inhibition of epithelial cell migration and invasion depends on the presence of the tryptophan residue in its sequence compared with similar derivative peptides. Therefore, GBPECP shows substantial potential as a novel delivery therapeutic through rapid and effective internalization and interference with cell mobility.

MMP-13 is involved in oral cancer cell metastasis.

The oral cancer cell line OC3-I5 with a highly invasive ability was selected and derived from an established OSCC line OC3. In this study, we demonstrated that matrix metalloproteinases protein MMP-13 was up-regulated in OC3-I5 than in OC3 cells. We also observed that expression of epithelial-mesenchymal transition (EMT) markers including Twist, p-Src, Snail1, SIP1, JAM-A, and vinculin were increased in OC3-I5 compared to OC3 cells, whereas E-cadherin expression was decreased in the OC3-I5 cells. Using siMMP-13 knockdown techniques, we showed that siMMP-13 not only reduced the invasion and migration, but also the adhesion abilities of oral cancer cells. In support of the role of MMP-13 in metastasis, we used MMP-13 expressing plasmid-transfected 293T cells to enhance MMP-13 expression in the OC3 cells, transplanting the MMP-13 over expressing OC3 cells into nude mice led to enhanced lung metastasis. In summary, our findings show that MMP-13 promotes invasion and metastasis in oral cancer cells, suggesting altered expression of MMP-13 may be utilized to impede the process of metastasis.

Hepatitis B virus PreS2-mutant large surface antigen activates store-operated calcium entry and promotes chromosome instability.

Hepatitis B virus (HBV) is a driver of hepatocellular carcinoma, and two viral products, X and large surface antigen (LHBS), are viral oncoproteins. During chronic viral infection, immune-escape mutants on the preS2 region of LHBS (preS2-LHBS) are gain-of-function mutations that are linked to preneoplastic ground glass hepatocytes (GGHs) and early disease onset of hepatocellular carcinoma. Here, we show that preS2-LHBS provoked calcium release from the endoplasmic reticulum (ER) and triggered stored-operated calcium entry (SOCE). The activation of SOCE increased ER and plasma membrane (PM) connections, which was linked by ER- resident stromal interaction molecule-1 (STIM1) protein and PM-resident calcium release- activated calcium modulator 1 (Orai1). Persistent activation of SOCE induced centrosome overduplication, aberrant multipolar division, chromosome aneuploidy, anchorage-independent growth, and xenograft tumorigenesis in hepatocytes expressing preS2- LHBS. Chemical inhibitions of SOCE machinery and silencing of STIM1 significantly reduced centrosome numbers, multipolar division, and xenograft tumorigenesis induced by preS2-LHBS. These results provide the first mechanistic link between calcium homeostasis and chromosome instability in hepatocytes carrying preS2-LHBS. Therefore, persistent activation of SOCE represents a novel pathological mechanism in HBV-mediated hepatocarcinogenesis.

A Heparan Sulfate-Binding Cell Penetrating Peptide for Tumor Targeting and Migration Inhibition.

As heparan sulfate proteoglycans (HSPGs) are known as co-receptors to interact with numerous growth factors and then modulate downstream biological activities, overexpression of HS/HSPG on cell surface acts as an increasingly reliable prognostic factor in tumor progression. Cell penetrating peptides (CPPs) are short-chain peptides developed as functionalized vectors for delivery approaches of impermeable agents. On cell surface negatively charged HS provides the initial attachment of basic CPPs by electrostatic interaction, leading to multiple cellular effects. Here a functional peptide (CPPecp) has been identified from critical HS binding region in hRNase3, a unique RNase family member with in vitro antitumor activity. In this study we analyze a set of HS-binding CPPs derived from natural proteins including CPPecp. In addition to cellular binding and internalization, CPPecp demonstrated multiple functions including strong binding activity to tumor cell surface with higher HS expression, significant inhibitory effects on cancer cell migration, and suppression of angiogenesis in vitro and in vivo. Moreover, different from conventional highly basic CPPs, CPPecp facilitated magnetic nanoparticle to selectively target tumor site in vivo. Therefore, CPPecp could engage its capacity to be developed as biomaterials for diagnostic imaging agent, therapeutic supplement, or functionalized vector for drug delivery.

A biologically inspired lung-on-a-chip device for the study of protein-induced lung inflammation.

This study reports a biomimetic microsystem that reconstitutes the lung microenvironment for monitoring the role of eosinophil cationic protein (ECP) in lung inflammation. ECP induces the airway epithelial cell expression of CXCL-12, which in turn stimulates the migration of fibrocytes towards the epithelium. This two-layered microfluidic system provides a feasible platform for perfusion culture, and was used in this study to reveal that the CXCL12-CXCR4 axis mediates ECP induced fibrocyte extravasation in lung inflammation. This 'lung-on-a-chip' microdevice serves as a dynamic transwell system by introducing a flow that can reconstitute the blood vessel-tissue interface for in vitro assays, enhancing pre-clinical studies. We made an attempt to develop a new microfluidic model which could not only simulate the transwell for studying cell migration, but could also study the migration in the presence of a flow mimicking the physiological conditions in the body. As blood vessels are the integral part of our body, this model gives an opportunity to study more realistic in vitro models of organs where the blood vessel i.e. flow based migration is involved.

A recombinant horseshoe crab plasma lectin recognizes specific pathogen-associated molecular patterns of bacteria through rhamnose.

Horseshoe crab is an ancient marine arthropod that, in the absence of a vertebrate-like immune system, relies solely on innate immune responses by defense molecules found in hemolymph plasma and granular hemocytes for host defense. A plasma lectin isolated from the hemolymph of Taiwanese Tachypleus tridentatus recognizes bacteria and lipopolysaccharides (LPSs), yet its structure and mechanism of action remain unclear, largely because of limited availability of horseshoe crabs and the lack of a heterogeneous expression system. In this study, we have successfully expressed and purified a soluble and functional recombinant horseshoe crab plasma lectin (rHPL) in an Escherichia coli system. Interestingly, rHPL bound not only to bacteria and LPSs like the native HPL but also to selective medically important pathogens isolated from clinical specimens, such as Gram-negative Pseudomonas aeruginosa and Klebsiella pneumoniae and Gram-positive Streptococcus pneumoniae serotypes. The binding was demonstrated to occur through a specific molecular interaction with rhamnose in pathogen-associated molecular patterns (PAMPs) on the bacterial surface. Additionally, rHPL inhibited the growth of P. aeruginosa PAO1 in a concentration-dependent manner. The results suggest that a specific protein-glycan interaction between rHPL and rhamnosyl residue may further facilitate development of novel diagnostic and therapeutic strategies for microbial pathogens.

Low-molecular-weight heparin and unfractionated heparin decrease Th-1, 2, and 17 expressions.

BACKGROUND: We evaluated the effects of T helper cell differentiation in a mite-allergic animal model treated with inhaled heparins of different molecular weight. METHOD: BALB/c mice were divided into four groups: 1. Control, 2. Mite intratracheal (mIT), 3. Inhaled heparin (hIN), 4. Inhaled low-molecular-weight heparin (lmwhIN). Groups 2, 3, and 4 were sensitized twice with Der p allergen subcutaneously on day 1 and day 8. Der p allergen was administered intratracheally on day 15. Groups 3 and 4 were treated with heparin or low-molecular-weight (lmw) heparin intranasally from day 1 to 22. Splenocytes from sacrificed mice stimulated with 16 µg/ml of Der p were cultured for 72 hours. Supernatants of splenocyte were collected to analyze the effect of Interleukin (IL)17-A/F, Interferon(IFN)-γ, IL-4, IL-13, and IL-10. Serum was also collected for Der P-specific IgE level on day 23. Total RNA was extracted from spleen tissue for mRNA expression. Gene expression of Foxp3, IL-10 IFN-γ, GATA3, IL-5, and RORγt were analyzed. RESULTS: Both hIN and lmwhIN groups had lower serum IgE level than that of the mIT group (both p<0.0001). Both hIN and lmwhIN groups showed significantly decreased transcripts of GATA-3, IFN-γ, IL-5, and RORγt mRNA in their spleen. Regarding the supernatant of splenocyte culture stimulated with Der p, compared with the mIT group, there were significant decreases in IL-17A/F, IFN-γ, IL-4, IL-13, and IL-10 secretion in inhaled hIN and lmwhIN groups. CONCLUSIONS: From this balb/c mice study, the analyses of mRNA and cytokines revealed that both intranasal heparin and lmw heparin treatment decreased the expression of Th1, Th2, and Th17 in spleen. The underlying mechanism(s) warrant further studies.

Crystal structures of starch binding domain from Rhizopus oryzae glucoamylase in complex with isomaltooligosaccharide: insights into polysaccharide binding mechanism of CBM21 family.

Glucoamylases are responsible for hydrolysis of starch and polysaccharides to yield ß-D-glucose. Rhizopus oryzae glucoamylase (RoGA) is composed of an N-terminal starch binding domain (SBD) and a C-terminal catalytic domain connected by an O-glycosylated linker. Two carbohydrate binding sites in RoSBD have been identified, site I is created by three highly conserved aromatic residues, Trp47, Tyr83, and Tyr94, and site II is built up by Tyr32 and Phe58. Here, the two crystal structures of RoSBD in complex with only α-(1,6)-linked isomaltotriose (RoSBD-isoG3) and isomaltotetraose (RoSBD-isoG4) have been determined at 1.2 and 1.3 Å, respectively. Interestingly, site II binding is observed in both complexes, while site I binding is only found in the RoSBD-isoG4 complex. Hence, site II acts as the recognition binding site for carbohydrate and site I accommodates site II to bind isoG4. Site I participates in sugar binding only when the number of glucosyl units of oligosaccharides is more than three. Taken together, two carbohydrate binding sites in RoSBD cooperate to reinforce binding mode of glucoamylase with polysaccharides as well as the starch.

Effects of novel human cathepsin S inhibitors on cell migration in human cancer cells.

Elevated cathepsin S (Cat S) level is correlated with higher migration ability in tumor cells. This study investigates the inhibitory effect of novel synthetic α-ketoamide compounds on cathepsin activity and cancer cell migration. The effect of several α-ketoamide compounds on the activity of recombinant cathepsins (Cat S, Cat L and Cat K) was examined. Two highly metastatic cancer cell lines were incubated with three Cat S-specific compounds (6n, 6 w and 6r) to analyze their effect on cellular Cat S activity and cell migration. At a 100 nM concentration, compounds 6n, 6r and 6 w effectively inhibited Cat S activity. Cat S activity and cell migration were significantly reduced in CL1-3 cells after treatment with either 6n or 6 w at 5 µM. Similar results were also obtained when A2058 cells were treated with 6n. These results highlight the therapeutic potential of α-ketoamide compounds, especially 6n and 6 w, to prevent or delay cancer metastasis.

Functional characterization of ECP-heparin interaction: a novel molecular model.

Human eosinophil cationic protein (ECP) and eosinophil derived neurotoxin (EDN) are two ribonuclease A (RNaseA) family members secreted by activated eosinophils. They share conserved catalytic triad and similar three dimensional structures. ECP and EDN are heparin binding proteins with diverse biological functions. We predicted a novel molecular model for ECP binding of heparin hexasaccharide (Hep6), [GlcNS(6S)-IdoA(2S)]3, and residues Gln(40), His(64) and Arg(105) were indicated as major contributions for the interaction. Interestingly, Gln(40) and His(64) on ECP formed a clamp-like structure to stabilize Hep6 in our model, which was not observed in the corresponding residues on EDN. To validate our prediction, mutant ECPs including ECP Q40A, H64A, R105A, and double mutant ECP Q40A/H64A were generated, and their binding affinity for heparins were measured by isothermal titration calorimetry (ITC). Weaker binding of ECP Q40A/H64A of all heparin variants suggested that Gln(40)-His(64) clamp contributed to ECP-heparin interaction significantly. Our in silico and in vitro data together demonstrate that ECP uses not only major heparin binding region but also use other surrounding residues to interact with heparin. Such correlation in sequence, structure, and function is a unique feature of only higher primate ECP, but not EDN.