Lysozyme as the anti-proliferative agent to block the interaction between S100A6 and the RAGE V domain

Digital spatial profiling identifies molecular changes involved in development of colitis-associated colorectal cancer

Objective

Chronic colonic inflammation seen in inflammatory bowel disease (IBD) is a risk factor for colorectal cancer (CRC). Colitis-associated cancers (CAC) are molecularly different from sporadic CRC. This study aimed to evaluate spatially defined molecular changes associated with neoplastic progression to identify mechanisms of action and potential biomarkers for prognostication.

Design

IBD patients who had undergone colectomy for treatment of their IBD or dysplasia were identified from an institutional database. Formalin-fixed paraffin embedded samples from areas of normal, inflamed, dysplastic and adenocarcinoma tissue were identified for digital spatial profiling using the Nanostring GeoMx™ Cancer Transcriptome Atlas. RNA expression and quantification of 1812 genes was measured and analysed in a spatial context to compare differences in gene expression.

Results

Sixteen patients were included, nine patients had CAC, two had dysplasia only and five had colitis only. Significant, step-wise differences in gene expression were seen between tissue types, mainly involving progressive over-expression of collagen genes associated with stromal remodelling. Similarly, MYC over-expression was associated with neoplastic progression. Comparison of normal and inflamed tissue from patients who progressed to those who did not also showed significant differences in immune-related genes, including under-expression of thte chemokines CCL18, CCL25 and IL-R7, as well as CD3, CD6 and lysozyme. The known oncogene CD24 was significantly overexpressed.

Conclusion

Both tissue types and patient groups are molecularly distinguishable on the basis of their gene expression patterns. Further prospective work is necessary to confirm these differences and establish their clinical significance and potential utility as biomarkers.

High-accuracy prediction of colorectal cancer chemotherapy efficacy using machine learning applied to gene expression data

Introduction: FOLFOX and FOLFIRI chemotherapy are considered standard first-line treatment options for colorectal cancer (CRC). However, the criteria for selecting the appropriate treatments have not been thoroughly analyzed. Methods: A newly developed machine learning model was applied on several gene expression data from the public repository GEO database to identify molecular signatures predictive of efficacy of 5-FU based combination chemotherapy (FOLFOX and FOLFIRI) in patients with CRC. The model was trained using 5-fold cross validation and multiple feature selection methods including LASSO and VarSelRF methods. Random Forest and support vector machine classifiers were applied to evaluate the performance of the models. Results and Discussion: For the CRC GEO dataset samples from patients who received either FOLFOX or FOLFIRI, validation and test sets were >90% correctly classified (accuracy), with specificity and sensitivity ranging between 85%-95%. In the datasets used from the GEO database, 28.6% of patients who failed the treatment therapy they received are predicted to benefit from the alternative treatment. Analysis of the gene signature suggests the mechanistic difference between colorectal cancers that respond and those that do not respond to FOLFOX and FOLFIRI. Application of this machine learning approach could lead to improvements in treatment outcomes for patients with CRC and other cancers after additional appropriate clinical validation.

Enantioselective effects of chiral prothioconazole and its metabolites: Oxidative stress in HepG2 cells and lysozyme activity

Chiral pesticides may exhibit enantioselectivity in terms of bioconcentration, environmental fate, and reproductive toxicity. Here, chiral prothioconazole and its metabolites were selected to thoroughly investigate their enantioselective toxicity and mechanisms at the molecular and cellular levels. Multispectral techniques revealed that the interaction between chiral PTC/PTCD and lysozyme resulted in the formation of a complex, leading to a change in the conformation of lysozyme. Meanwhile, the effect of different conformations of PTC/PTCD on the conformation of lysozyme differed, and its metabolites were able to exert a greater effect on lysozyme compared to prothioconazole. Moreover, the S-configuration of PTCD interacted most strongly with lysozyme. This conclusion was further verified by DFT calculations and molecular docking as well. Furthermore, the oxidative stress indicators within HepG2 cells were also affected by chiral prothioconazole and its metabolites. Specifically, S-PTCD induced more substantial perturbation of the normal oxidative stress processes in HepG2 cells, and the magnitude of the perturbation varied significantly among different configurations (P > 0.05). Overall, chiral prothioconazole and its metabolites exhibit enantioselective effects on lysozyme conformation and oxidative stress processes in HepG2 cells. This work provides a scientific basis for a more comprehensive risk assessment of the environmental behaviors and effects caused by chiral pesticides, as well as for the screening of highly efficient and less biotoxic enantiomeric monomers.

Unraveling the Interaction of Diflunisal with Cyclodextrin and Lysozyme by Fluorescence Spectroscopy

Understanding the interaction between the drug:carrier complex and protein is essential for the development of a new drug-delivery system. However, the majority of reports are based on an understanding of interactions between the drug and protein. Here, we present our findings on the interaction of the anti-inflammatory drug diflunisal with the drug carrier cyclodextrin (CD) and the protein lysozyme, utilizing steady-state and time-resolved fluorescence spectroscopy. Our findings reveal a different pattern of molecular interaction between the inclusion complex of β-CD (β-CD) or hydroxypropyl-β-CD (HP-β-CD) (as the host) and diflunisal (as the guest) in the presence of protein lysozyme. The quantum yield for the 1:2 guest:host complex is twice that of the 1:1 guest:host complex, indicating a more stable hydrophobic microenvironment created in the 1:2 complex. Consequently, the nonradiative decay pathway is significantly reduced. The interaction is characterized by ultrafast solvation dynamics and time-resolved fluorescence resonance energy transfer. The solvation dynamics of the lysozyme becomes 10% faster under the condition of binding with the drug, indicating a negligible change in the polar environment after binding. In addition, the fluorescence lifetime of diflunisal (acceptor) is increased by 50% in the presence of the lysozyme (donor), which indicates that the drug molecule is bound to the binding pocket on the surface of the protein, and the average distance between active tryptophan in the hydrophobic region and diflunisal is calculated to be approximately 50 Å. Excitation and emission matrix spectroscopy reveals that the tryptophan emission increases 3-5 times in the presence of both diflunisal and CD. This indicates that the tryptophan of lysozyme may be present in a more hydrophobic environment in the presence of both diflunisal and CD. Our observations on the interaction of diflunisal with β-CD and lysozyme are well supported by molecular dynamics simulation. Results from this study may have an impact on the development of a better drug-delivery system in the future. It also reveals a fundamental molecular mechanism of interaction of the drug-carrier complex with the protein.

S100A6: molecular function and biomarker role

S100A6 (also called calcyclin) is a Ca2+-binding protein that belongs to the S100 protein family. S100A6 has many functions related to the cytoskeleton, cell stress, proliferation, and differentiation. S100A6 also has many interacting proteins that are distributed in the cytoplasm, nucleus, cell membrane, and outside the cell. Almost all these proteins interact with S100A6 in a Ca2+-dependent manner, and some also have specific motifs responsible for binding to S100A6. The expression of S100A6 is regulated by several transcription factors (such as c-Myc, P53, NF-κB, USF, Nrf2, etc.). The expression level depends on the specific cell type and the transcription factors activated in specific physical and chemical environments, and is also related to histone acetylation, DNA methylation, and other epigenetic modifications. The differential expression of S100A6 in various diseases, and at different stages of those diseases, makes it a good biomarker for differential diagnosis and prognosis evaluation, as well as a potential therapeutic target. In this review, we mainly focus on the S100A6 ligand and its transcriptional regulation, molecular function (cytoskeleton, cell stress, cell differentiation), and role as a biomarker in human disease and stem cells.

Independent antioxidant and anticancer properties of a novel thermostable lysozyme isolated from Bacillus paralicheniformis: in silico and in vitro studies

In this study, we evaluated the independent anticancer properties of a novel heat-stable lysozyme derived from the thermophilic bacterium Bacillus paralicheniformis (BplzC) to identify potential alternative therapies to address the suboptimal outcomes of current cancer treatments. Using the String 10.5 database, an in-silico protein-protein interaction study predicted that BplzC was a strong functional partner of cytochrome c, indicating a potential role in cancer cell apoptosis. Further, the HDOCK server predicted that BplzC strongly bound to cell death receptors, such as cytokines FAS receptor, leading to activation of cytochrome c and subsequent apoptosis in the cancer cell line. In vitro assays demonstrated uniform apoptotic activity of BplzC against various cancer cell lines, while showing no apoptotic activity against normal non-cancer cell lines. And showing no apoptotic activity against normal non-cancer cell lines suggested a very specific mode of action and without any adverse side effects. Additionally, BplzC exhibited ROS scavenging activity and reducing ability comparable to ascorbic acid, and significantly accelerated HEK293 cell migration. Our findings suggest that BplzC has specific cytotoxic effects on cancer cells and may be a valuable natural source of antioxidants for future use in the nutritional and pharmaceutical sectors.

Identification of Protein Quality Markers in Toad Venom from Bufo gargarizans

Toad venom is a traditional Chinese medicine with high medicinal value. The existing quality evaluation standards of toad venom have obvious limitations because of the lack of research on proteins. Thus, it is necessary to screen suitable quality markers and establish appropriate quality evaluation methods for toad venom proteins to guarantee their safety and efficacy in clinical applications. SDS-PAGE, HPLC, and cytotoxicity assays were used to analyze differences in protein components of toad venom from different areas. Functional proteins were screened as potential quality markers by proteomic and bioinformatic analyses. The protein components and small molecular components of toad venom were not correlated in content. Additionally, the protein component had strong cytotoxicity. Proteomics analysis showed that 13 antimicrobial proteins, four anti-inflammatory and analgesic proteins, and 20 antitumor proteins were differentially expressed extracellular proteins. A candidate list of functional proteins was coded as potential quality markers. Moreover, Lysozyme C-1, which has antimicrobial activity, and Neuropeptide B (NPB), which has anti-inflammatory and analgesic activity, were identified as potential quality markers for toad venom proteins. Quality markers can be used as the basis of quality studies of toad venom proteins and help to construct and improve safe, scientific, and comprehensive quality evaluation methods.

Proteins and their functionalization for finding therapeutic avenues in cancer: Current status and future prospective

Despite the remarkable advancement in the health care sector, cancer remains the second most fatal disease globally. The existing conventional cancer treatments primarily include chemotherapy, which has been associated with little to severe side effects, and radiotherapy, which is usually expensive. To overcome these problems, target-specific nanocarriers have been explored for delivering chemo drugs. However, recent reports on using a few proteins having anticancer activity and further use of them as drug carriers have generated tremendous attention for furthering the research towards cancer therapy. Biomolecules, especially proteins, have emerged as suitable alternatives in cancer treatment due to multiple favourable properties including biocompatibility, biodegradability, and structural flexibility for easy surface functionalization. Several in vitro and in vivo studies have reported that various proteins derived from animal, plant, and bacterial species, demonstrated strong cytotoxic and antiproliferative properties against malignant cells in native and their different structural conformations. Moreover, surface tunable properties of these proteins help to bind a range of anticancer drugs and target ligands, thus making them efficient delivery agents in cancer therapy. Here, we discuss various proteins obtained from common exogenous sources and how they transform into effective anticancer agents. We also comprehensively discuss the tumor-killing mechanisms of different dietary proteins such as bovine α-lactalbumin, hen egg-white lysozyme, and their conjugates. We also articulate how protein nanostructures can be used as carriers for delivering cancer drugs and theranostics, and strategies to be adopted for improving their in vivo delivery and targeting. We further discuss the FDA-approved protein-based anticancer formulations along with those in different phases of clinical trials.

S100A6 Protein-Expression and Function in Norm and Pathology

S100A6, also known as calcyclin, is a calcium-binding protein belonging to the S100 protein family. It was first identified and purified more than 30 years ago. Initial structural studies, focused mostly on the mode and affinity of Ca²⁺ binding and resolution of the resultant conformational changes, were soon complemented by research on its expression, localization and identification of binding partners. With time, the use of biophysical methods helped to resolve the structure and versatility of S100A6 complexes with some of its ligands. Meanwhile, it became clear that S100A6 expression was altered in various pathological states and correlated with the stage/progression of many diseases, including cancers, indicative of its important, and possibly causative, role in some of these diseases. This, in turn, prompted researchers to look for the mechanism of S100A6 action and to identify the intermediary signaling pathways and effectors. After all these years, our knowledge on various aspects of S100A6 biology is robust but still incomplete. The list of S100A6 ligands is growing all the time, as is our understanding of the physiological importance of these interactions. The present review summarizes available data concerning S100A6 expression/localization, interaction with intracellular and extracellular targets, involvement in Ca²⁺-dependent cellular processes and association with various pathologies.

Molecular recognition of two bioactive coumarin derivatives 7-hydroxycoumarin and 4-methyl-7-hydroxycoumarin by hen egg white lysozyme: Exploring the binding mechanism, thermodynamic parameters and structural changes using multispectroscopic and computational approaches

Multispectroscopic and computational methods of exploring the interaction between a carrier protein and therapeutic compounds provide a preliminary investigation into establishing the efficacy of such compounds. Here, two coumarin derivatives, 7-hydroxycoumarin (7-HC) and 4-methyl-7-hydroxycoumarin (4-Me-7-HC), were selected to carry out numerous biophysical interaction studies with a model carrier protein, hen egg white lysozyme (HEWL). Fluorescence spectroscopy studies conducted between HEWL and 7-HC/4-Me-7-HC revealed the binding constants (K_b) were in the range of 10⁴ M^-1, indicating a moderate nature of binding. The quenching mechanism observed during complexation process was an unusual static quenching due to the effect of temperature on the rate constant. Thermodynamic parameters revealed a positive ΔH and ΔS for HEWL-7-HC/4-Me-7-HC, indicating hydrophobic forces played a dominant role in the interaction process. FRET studies suggested a possible non-radiative energy transfer from the donor (HEWL) to the acceptor (coumarins). Molecular docking studies revealed the interaction of 7-HC/4-Me-7-HC with intrinsic fluorophores, Trp63 and Trp108, Trp108 being an essential residue for binding as proven by molecular dynamic (MD) simulation. MD simulation studies also indicated conformational stability gained by HEWL upon interaction with 7-HC and 4-Me-7-HC. The microenvironment surrounding the Trp residues showed a significant Stoke's shift on carrying out 3-D fluorescence. CD studies revealed a decrease in the alpha helical content of HEWL upon interacting with the ligands. Enzymatic assay conducted for HEWL in the presence of 7-HC/4-Me-7-HC saw an increase in the activity of HEWL, suggesting a change in structural conformation and stability of the protein, altering its activity.Communicated by Ramaswamy H. Sarma.

Lysozyme and Its Application as Antibacterial Agent in Food Industry

Lysozymes are hydrolytic enzymes characterized by their ability to cleave the β-(1,4)-glycosidic bonds in peptidoglycan, a major structural component of the bacterial cell wall. This hydrolysis action compromises the integrity of the cell wall, causing the lysis of bacteria. For more than 80 years, its role of antibacterial defense in animals has been renowned, and it is also used as a preservative in foods and pharmaceuticals. In order to improve the antimicrobial efficacy of lysozyme, extensive research has been intended for its modifications. This manuscript reviews the natural antibiotic compound lysozyme with reference to its catalytic and non-catalytic mode of antibacterial action, lysozyme types, susceptibility and resistance of bacteria, modification of lysozyme molecules, and its applications in the food industry.

Recombinant expression of hen egg white lysozyme with the assistance of xylanase fusion partner in Pichia pastoris

Due to its bacteriolytic activity, hen egg white lysozyme (HEWL) is widely used in the feed, food, and pharmaceutical industries. However, its application is hindered by low protein expression levels in microbial expression systems. In this work, a novel fusion protein expression strategy was proposed for increasing the expression level of HEWL. First, HEWL, fused with a highly expressed fusion protein partner xylanase XynCDBFV, is expressed in Pichia pastoris. Secondly, a linker including endogenous protease cleavage sites was introduced between two fusion proteins in order to separate them directly during the secretion process. Finally, the results show that the supernatant of XynCDBFV-HEWL has a higher HEWL expression level and activity compared with HEWL only. It should be noted that the expression of HEWL reaches to about 3.5 g/L, and the activity of HEWL against Micrococcus lysodeikticus reaches to 1.50 × 10⁵ U/mL in a fed-batch fermentation, which is currently the highest level of recombinant expression of an egg white-derived lysozyme. Taken together, we acquired bioactive HEWL for large-scale recombinant production in Pichia pastoris using a novel fusion protein expression strategy, which could then be used for a variety of applications.

Advancements in Biodegradable Active Films for Food Packaging: Effects of Nano/Microcapsule Incorporation

Food packaging plays a fundamental role in the modern food industry as a main process to preserve the quality of food products from manufacture to consumption. New food packaging technologies are being developed that are formulated with natural compounds by substituting synthetic/chemical antimicrobial and antioxidant agents to fulfill consumers' expectations for healthy food. The strategy of incorporating natural antimicrobial compounds into food packaging structures is a recent and promising technology to reach this goal. Concepts such as "biodegradable packaging", "active packaging", and "bioactive packaging" currently guide the research and development of food packaging. However, the use of natural compounds faces some challenges, including weak stability and sensitivity to processing and storage conditions. The nano/microencapsulation of these bioactive compounds enhances their stability and controls their release. In addition, biodegradable packaging materials are gaining great attention in the face of ever-growing environmental concerns about plastic pollution. They are a sustainable, environmentally friendly, and cost-effective alternative to conventional plastic packaging materials. Ultimately, a combined formulation of nano/microencapsulated antimicrobial and antioxidant natural molecules, incorporated into a biodegradable food packaging system, offers many benefits by preventing food spoilage, extending the shelf life of food, reducing plastic and food waste, and preserving the freshness and quality of food. The main objective of this review is to illustrate the latest advances in the principal biodegradable materials used in the development of active antimicrobial and antioxidant packaging systems, as well as the most common nano/microencapsulated active natural agents incorporated into these food-packaging materials.

Dietary recombinant human lysozyme improves the growth, intestinal health, immunity and disease resistance of Pacific white shrimp Litopenaeus vannamei

The present study was conducted to investigate the effects of dietary recombinant human lysozyme (RHL) on the growth, immune response, anti-oxidative activity, intestinal morphology, intestinal microflora and disease resistance of shrimp Litopenaeus vannamei. Shrimps with an initial body weight of 2.36 ± 0.02 g were fed diets supplemented with 0 (control group, R0), 0.0025% (R1), 0.005% (R2), 0.01% (R3), 0.02% (R4) and 0.04% (R5) of RHL, respectively. After a 10-week feeding trial, the final body weight, survival rate, weight gain ratio and protein efficiency rate of the shrimps in dietary RHL supplemented groups were significantly higher than that in the control group, while feed conversion ratio was significantly lower (P < 0.05). The total haemocyte count, total anti-oxidative capacity, respiratory burst, activities of phagocytosis, nitric oxide synthase, phenol oxidase and lysozyme in serum were significantly higher in dietary RHL supplemented groups than those in the control group (P < 0.05). Meanwhile, the intestinal pile height and wall thickness were significantly higher in dietary RHL supplemented groups than those in the control group (P < 0.05). Dietary RHL significantly improved the expressions of immune-related genes in gill, such as lipopolysaccharide-β-glucan binding protein, Toll, immune deficiency, heat shock protein 70 and Crustin (P < 0.05). The abundance of proteobacteria and bacteroidetes in intestine was higher, while the abundance of firmicutes and cyanobacteria was lower than those in the control group at the phylum level. In addition, dietary RHL supplementation significantly improved the protective ability of shrimp against V. parahaemolyticus infection (P < 0.05). Based on the broken-line model analysis for weight gain ratio after the feeding trial, the optimal level of dietary RHL supplementation for shrimp was estimated to be 0.006375%.

Synthesis of Novel Suramin Analogs With Anti-Proliferative Activity via FGF1 and FGFRD2 Blockade

A promising approach in cancer therapy is the inhibition of cell proliferation using small molecules. In this study, we report the synthesis of suramin derivatives and their applications. We used NMR spectroscopy and docking simulations to confirm binding sites and three-dimensional models of the ligand-protein complex. The WST-1 assay was used to assess cell viability and cell proliferation in vitro to evaluate the inhibition of protein-protein interactions and to investigate the anti-proliferative activities in a breast cancer cell line. All the suramin derivatives showed anti-proliferative activity by blocking FGF1 binding to its receptor FGFRD2. The dissociation constant was measured by fluorescence spectroscopy. The suramin compound derivatives synthesized herein show potential as novel therapeutic agents for their anti-proliferative activity via the inhibition of protein-protein interactions. The cytotoxicity of these suramin derivatives was lower than that of the parent suramin compound, which may be considered a significant advancement in this field. Thus, these novel suramin derivatives may be considered superior anti-metastasis molecules than those of suramin.

Recent Insights Into the Prognostic and Therapeutic Applications of Lysozymes

Lysozymes are naturally occurring enzymes present in a variety of biological organisms, such as bacteria, fungi, and animal bodily secretions and tissues. It is also the main ingredient of many ethnomedicines. It is well known that lysozymes and lysozyme-like enzymes can be used as anti-bacterial agents by degrading bacterial cell wall peptidoglycan that leads to cell death, and can also inhibit fungi, yeasts, and viruses. In addition to its direct antimicrobial activity, lysozyme is also an important component of the innate immune system in most mammals. Increasing evidence has shown the immune-modulatory effects of lysozymes against infection and inflammation. More recently, studies have revealed the anti-cancer activities of lysozyme in multiple types of tumors, potentially through its immune-modulatory activities. In this review, we summarized the major functions and underlying mechanisms of lysozymes derived from animal and plant sources. We highlighted the therapeutic applications and recent advances of lysozymes in cancers, hypertension, and viral diseases, aiming toseeking alternative therapies for standard medical treatment bypassing side effects. We also evaluated the role of lysozyme as a promising cancer marker for prognosis to indicate the outcomes recurrence for patients.

Rapid and noninvasive diagnosis of oral and oropharyngeal cancer based on micro-Raman and FT-IR spectra of saliva

Fast, sensitive, and noninvasive techniques are needed for better health care management, particularly when traditional biopsies could be replaced with appropriate analyses of body fluids, such as saliva. Here is presented a proof-of-concept study, which aims to test a recently developed saliva samples preparation method, for oral and oropharyngeal cancer diagnosis, using micro-Raman and Fourier transform infrared (FT-IR) spectroscopic techniques. The detected biomarker bands and the cancer classification rates are compared and discussed. Saliva samples were collected from healthy donors and pathologically confirmed oral and oropharyngeal cancer patients. Principal components analysis (PCA) and principal components analysis-linear discriminant analysis (PCA-LDA) chemometric methods were applied to build discrimination models for the test and control groups. Based on the differences between salivary spectra of healthy and cancer patients, several biomarker bands were identified. Noteworthy, a significant vibrational biomarker band at 2064 cm^-1, assigned to thiocyanate, was observed in both the FT-IR and Raman data-set. Other cancer characteristic Raman bands were 754 cm^-1 (tryptophan), 530 and 927 cm^-1 (lysozyme), 1001 cm^-1 (phenylalanine), while the FT-IR biomarker band was located at 1075 cm^-1 (phosphodiester bonds stretching in DNA, RNA). The oral and oropharyngeal cancer was classified with an accuracy of 90% based on the micro-Raman data and 82% based on the FT-IR data set, respectively. The study showed that oral and oropharyngeal cancer can be differentiated from control saliva samples based on their respective micro-Raman and FT-IR spectral signatures, due to the biomolecular modifications induced by the disease.

Noncovalent molecular interactions between antineoplastic drug gemcitabine and a carrier protein identified through spectroscopic and in silico methods

Herein we have studied the noncovalent molecular interactions between hen egg white lysozyme (HEWL) and the commonly employed antineoplastic drug gemcitabine through the cumulative implementation of spectroscopic techniques and in silico approaches. The formation of a complex between HEWL and gemcitabine was made evident by the differences between the UV-visible spectra of the protein and protein-gemcitabine complex. Fluorescence quenching of HEWL by gemcitabine was hardly detectable at room temperature, but it became prominent at higher temperatures. Very low values for the bimolecular quenching constant and the non-reciprocal dependence of quenching on temperature indicated that dynamic quenching was taking place. Analysis of experimental data indicated that the interaction was dominated by hydrophobic forces, while the results of a computational investigation suggested the concomitant contribution of hydrogen bonding. Gemcitabine binding induced modifications of the secondary structure of HEWL by slightly increasing the α-helical content of the protein. Finally, gemcitabine binding site was inferred to be located in HEWL big hydrophobic cavity.

Blocking the interface region amongst S100A6 and RAGE V domain via S100B protein

The Ca²⁺-mediated S100 family protein S100A6 has a crucial task in various intracellular and extracellular activities thereby demonstrating a possible involvement in the advancement and development of malignant tumors. S100A6 has been found to associate with receptor for advanced glycation end products, RAGE, through its extracellular extension. This extension is famously identified as a prominent receptor for many S100 family associates. Additionally, S100A6 binds to S100B protein and forms a heterodimer. Thus, we consider the S100B protein to be a prospective drug molecule to obstruct the interacting regions amongst S100A6 and RAGE V domain. We applied the NMR spectroscopy method to locate the binding area amid the S100A6m (mutant S100A6, cysteine at 3rd position of S100A6 is replaced with serine, C3S) and S100B proteins. The ¹H-¹⁵N HSQC NMR titrations revealed the probable requisite dynamics of S100A6m and S100B interfaces. Utilizing data from the NMR titrations as input parameters, we ran the HADDOCK program and created a S100A6m-S100B heterodimer complex. The obtained complex was then superimposed with the reported complex of S100A6m-RAGE V domain. This superimposition displayed the possibility of S100B to be a potential antagonist that can block the interface area of the S100A6m and the RAGE V domain. Moreover, an in vitro cancer model using SW480 cells in water-soluble tetrazolium-1 assay (WST-1) showed a noticeable change in the cell proliferation as an effect of these proteins. Our study indicates the possibility to develop a S100B-like competitor that could play a key role in the treatment of S100- and RAGE-mediated human diseases.

Biophysical Insight into the Interaction of Human Lysozyme with Anticancer Drug Anastrozole: A Multitechnique Approach

In the present study, we employ fluorescence spectroscopy, dynamic light scattering, and molecular docking methods. Binding of anticancer drug anastrozole with human lysozyme (HL) is studied. Binding of anastrozole to HL is moderate but spontaneous. There is anastrozole persuaded hydrodynamic change in HL, leading to molecular compaction. Binding of anastrozole to HL also decreased in vitro lytic activity of HL. Molecular docking results suggest the electrostatic interactions and van der Waals forces played key role in binding interaction of anastrozole near the catalytic site. Binding interaction of anastrozole to proteins other than major transport proteins in blood can significantly affect pharmacokinetics of this molecule. Hence, rationalizing drug dosage is important. This study also points to unrelated effects that small molecules bring in the body that are considerable and need thorough investigation.

Pentamidine inhibit S100A4 - p53 interaction and decreases cell proliferation activity

Metastasis-associated S100A4 protein is a small calcium-binding protein typically overexpressed in several tumor forms, and it is widely accepted that S100A4 plays a significant role in the metastasis of cancer. Tumor suppressor p53 is one of the S100A4's main targets. Previous reports show that through p53, S100A4 regulates collagen expression and cell proliferation. When S100A4 interacts with p53, the S100A4 destabilizes wild type p53. In the current study, based on ¹H-¹⁵N HSQC NMR experiments and HADDOCK results, S100A4 interacts with the intrinsically unstructured transactivation domain (TAD) of the protein p53 and the pentamidine molecules in the presence of calcium ions. Our results suggest that the p53 TAD and pentamidine molecules share similar binding sites on the S100A4 protein. This observation indicates that a competitive binding mechanism can interfere with the binding of S100A4-p53 and increase the level of p53. Also, we compare different aspects of p53 activity in the WST-1 test using MCF 7 cells. We found that the presence of a pentamidine molecule results in higher p53 activity, which is also reflected in less cell proliferation. Collectively, our results indicate that disrupting the S100A4-p53 interaction would prevent cancer progression, and thus S100A4-p53 inhibitors provide a new avenue for cancer therapy.

FRET-Based Aptasensor for the Selective and Sensitive Detection of Lysozyme

Lysozyme is a conserved antimicrobial enzyme and has been cited for its role in immune modulation. Increase in lysozyme concentration in body fluids is also regarded as an early warning of some diseases such as Alzheimer’s, sarcoidosis, Crohn’s disease, and breast cancer. Therefore, a method for a sensitive and selective detection of lysozyme can benefit many different areas of research. In this regard, several aptamers that are specific to lysozyme have been developed, but there is still a lack of a detection method that is sensitive, specific, and quantitative. In this work, we demonstrated a single-molecule fluorescence resonance energy transfer (smFRET)-based detection of lysozyme using an aptamer sensor (also called aptasensor) in which the binding of lysozyme triggers its conformational switch from a low-FRET to high-FRET state. Using this strategy, we demonstrated that the aptasensor is sensitive down to 2.3 picomoles (30 nM) of lysozyme with a dynamic range extending to ~2 µM and has little to no interference from similar biomolecules. The smFRET approach used here requires a dramatically small amount of aptasensor (~3000-fold less as compared to typical bulk fluorescence methods), and it is cost effective compared to enzymatic and antibody-based approaches. Additionally, the aptasensor can be readily regenerated in situ via a process called toehold mediated strand displacement (TMSD). The FRET-based aptasensing of lysozyme that we developed here could be implemented to detect other protein biomarkers by incorporating protein-specific aptamers without the need for changing fluorophore-labeled DNA strands.