Targeting heat shock proteins on cancer cells: selection, characterization, and cell-penetrating properties of a peptidic GRP78 ligand

Engineered phages in anti-infection and anti-tumor fields: A review

The abuse of antibiotics has led to the widespread emergence of multi-drug resistant bacteria. Phage therapy holds promise for enhancing anti-bacterial and anti-infection strategies. Traditional phage therapy employs phage preparations as an alternative to antibiotics for the eradication of bacteria, aiming to achieve the desired clinical outcomes. Modification of phage by transgene or chemical modification overcomes the limitations of traditional phage therapy, including host spectrum modification, bacterial resistance reversal, antigen presentation, and drug targeted delivery, and thus broadens the application field of phages. This article summarizes the progress of engineered phages in the fields of anti-bacterial, anti-infective and anti-tumor therapy. It emphasizes the advantages of engineered phages in anti-bacterial and anti-tumor treatment, and discusses the widespread potential of phage-based modular design as multifunctional biopharmaceuticals, drug carriers, and other applications.

A novel bispecific T-cell engager using the ligand-target csGRP78 against acute myeloid leukemia

Current medical therapies for treating acute myeloid leukemia (AML) remain unmet, and AML patients may benefit from targeted immunotherapy approaches that focus on specific tumor antigens. GRP78, which is upregulated in various malignant tumors such as AML, is partially expressed as cell surface GRP78 (csGRP78) on the cell membrane, making it an ideal target for redirecting T cells, including T-cell engagers. However, considering the conventional approach of using two scFv segments to construct a bispecific T-cell engager (BiTE), we have undertaken the development of a novel BiTE that utilizes a cyclic peptide ligand to specifically target csGRP78, which we refer to as GRP78-CD3/BiTE. We studied the effects of GRP78-CD3/BiTE on treatments for AML in vitro and in vivo and assessed the pharmacokinetics of this engager. Our findings demonstrated that GRP78-CD3/BiTE could not only effectively mediate the cytotoxicity of T cells against csGRP78-expressing AML cells but also specifically eliminate primary AML tumor cells in vitro. Furthermore, GRP78-CD3/BiTE exhibited a longer half-life despite having a lower molecular weight than CD19-CD3/BiTE. In a xenograft mouse model of AML, treatment with GRP78-CD3/BiTE prolonged the survival time of the mice. Our findings demonstrate that GRP78-CD3/BiTE is effective and selective for eliminating csGRP78-expressing AML cells and suggest that this approach to targeted immunotherapy could lead to effective new treatments for AML.

SARS-CoV-2 Spike Protein-Derived Cyclic Peptides as Modulators of Spike Interaction with GRP78

The human glucose-regulated protein GRP78 is a human chaperone that translocactes to the cell surface when cells are under stress. Theoretical studies suggested it could be involved in SARS-CoV-2 virus entry to cells. In this work, we used in vitro surface plasmon resonance-based assays to show that human GRP78 indeed binds to SARS-CoV-2 spike protein. We have designed and synthesised cyclic peptides based on the loop structure of amino acids 480-488 of the SARS-CoV-2 spike protein S1 domain from the Wuhan and Omicron variants and showed that both peptides bind to GRP78. Consistent with the greater infectiousness of the Omicron variant, the Omicron-derived peptide displays slower dissociation from the target protein. Both peptides significantly inhibit the binding of wild-type S1 protein to the human protein GRP78 suggesting that further development of these cyclic peptide motifs may provide a viable route to novel anti-SARS-CoV-2 agents.

Acetylcholinesterase - glucose-regulated protein 78 binding site prediction, a hope to cure neurological disorders such as Alzheimer's disease

Cerebral amyloid plaques in the brain define the elderly neuralgic disorder, Alzheimer's disease (AD). The enzyme Acetylcholinesterase (AChE) was reported to play a vital role in AD. It was shown that AChE induces amyloid fibril formation forming highly toxic AChE-Amyloid-β (Aβ) complexes. AChE can accelerate amyloid formation, and its inhibition could prevent such alterations to the enzyme. Understanding the proteostasis of AChE and its binding site to cellular chaperone GRP78 (Glucose-regulated protein 78) would help find a treatment for AD. In this study, the state of the art computational tools were utilized to predict the binding location of AChE that can stably associate with the cellular chaperone, GRP78. Sequence comparison along with molecular docking predicts two binding locations on AChE (C69-C96 and C257-C272) that could bind to GRP78 substrate binding domain β (SBDβ). The analysis of the docking data suggests that the former location has the best average binding affinity value (-12.16 kcal/mol) and average interaction pattern (13.9 ± 3.5 H-bonds, 5.5 ± 1.4 hydrophobic contacts, and 1.4 ± 1.2 salt bridges).

Enhancing precision medicine: Bispecific antibody-mediated targeted delivery of lipid nanoparticles for potential cancer therapy

The precise delivery of therapeutic agents to specific cell populations, including cancer cells, remains a target in modern medicine, to enhance treatment efficacy, while minimizing unintended side effects. This study presents a strategy utilizing bispecific antibodies for the targeted delivery of nucleic acid drugs to the surface of glucose-regulated protein 78 (GRP78)-overexpressing cancer cells. Strong binding affinity of the bispecific antibodies to GRP78-overexpressing cancer cells, including HEPG2 cells, confirmed the tumor-targeting potential of this platform. Functional analyses demonstrated the role of the bispecific antibodies in enhancing lipid nanoparticle (LNP) uptake, causing increased gene expression levels of nucleic acid drugs loaded within LNPs. In vivo imaging confirmed the potency of the bispecific-antibody-modified LNPs in delivering nucleic acid drugs to tumors and sustaining therapeutic expression levels. In vivo therapy results indicated that the bispecific antibodies improved the antitumor activity of PE38-loaded LNPs in tumors overexpressing surface GRP78. This study pioneered a bispecific-antibody-centered platform for the targeted delivery of nucleic acid drugs. The robust antigen-antibody binding affinity, tumor-selective interactions, enhanced cellular uptake, and proficient gene expression promise to advance precision therapeutics in oncology. Continued refinement and translation of this drug delivery strategy are important to unlock its full clinical potential.

Binding site prediction between lysozyme and glucose-regulated protein 78, a hope to fight amyloidosis

Amyloidosis is an extraordinarily vigorous and heterogeneous group of disorders that causes numerous organ failures due to the precipitation of misfolded proteins. Many of these damaged proteins are discarded before causing any fatal diseases due to the contribution of the protein quality control (PQC) system and its chaperons, including glucose-regulated protein (GRP78). One of the most important enzymatic proteins inside the body is lysozyme, which is reported to have many mutated variants that may cause amyloid fibrils. This study used structural bioinformatics and molecular dynamics simulations to test and suggest binding sites for the human lysozyme protein with GRP78. Multiple sequence alignment (MSA) shows that part of the lysozyme envelope protein (C65-C81 cyclic region) has high similarities (30.77% identity) with the cyclic Pep42. Additionally, the binding between the lysozyme cyclic region (C65-C81) and GRP78 substrate binding domain (SBD) is found favorable. The number and types of interactions vary between each of the mutant isoforms of lysozyme. The more significant the conformational changes in the mutation, the greater its probability of aggregation and the formation of amyloid fibrils. Each mutation leads to different interactions and binding patterns with GRP78. The present computational study suggests a lysozyme-GRP78 binding site, thus paving the way for drug designers to construct suitable carriers that can collect misfolded lysozyme proteins and eliminate them from the body, preventing their aggregation and amyloidogenesis.Communicated by Ramaswamy H. Sarma.

Peptide-scFv antigen recognition domains effectively confer CAR T cell multiantigen specificity

The emergence of immune escape is a significant roadblock to developing effective chimeric antigen receptor (CAR) T cell therapies against hematological malignancies, including acute myeloid leukemia (AML). Here, we demonstrate feasibility of targeting two antigens simultaneously by combining a GRP78-specific peptide antigen recognition domain with a CD123-specific scFv to generate a peptide-scFv bispecific antigen recognition domain (78.123). To achieve this, we test linkers with varying length and flexibility and perform immunophenotypic and functional characterization. We demonstrate that bispecific CAR T cells successfully recognize and kill tumor cells that express GRP78, CD123, or both antigens and have improved antitumor activity compared to their monospecific counterparts when both antigens are expressed. Protein structure prediction suggests that linker length and compactness influence the functionality of the generated bispecific CARs. Thus, we present a bispecific CAR design strategy to prevent immune escape in AML that can be extended to other peptide-scFv combinations.

Identification of a druggable site on GRP78 at the GRP78-SARS-CoV-2 interface and virtual screening of compounds to disrupt that interface

SARS-CoV-2, the virus that causes COVID-19, led to a global health emergency that claimed the lives of millions. Despite the widespread availability of vaccines, the virus continues to exist in the population in an endemic state which allows for the continued emergence of new variants. Most of the current vaccines target the spike glycoprotein interface of SARS-CoV-2, creating a selection pressure favoring viral immune evasion. Antivirals targeting other molecular interactions of SARS-CoV-2 can help slow viral evolution by providing orthogonal selection pressures on the virus. GRP78 is a host auxiliary factor that mediates binding of the SARS-CoV-2 spike protein to human cellular ACE2, the primary pathway of cell infection. As GRP78 forms a ternary complex with SARS-CoV-2 spike protein and ACE2, disrupting the formation of this complex is expected to hinder viral entry into host cells. Here, we developed a model of the GRP78-Spike RBD-ACE2 complex. We then used that model together with hot spot mapping of the GRP78 structure to identify the putative binding site for spike protein on GRP78. Next, we performed structure-based virtual screening of known drug/candidate drug libraries to identify binders to GRP78 that are expected to disrupt spike protein binding to the GRP78, and thereby preventing viral entry to the host cell. A subset of these compounds has previously been shown to have some activity against SARS-CoV-2. The identified hits are starting points for the further development of novel SARS-CoV-2 therapeutics, potentially serving as proof-of-concept for GRP78 as a potential drug target for other viruses.

GRP78-CAR T cell effector function against solid and brain tumors is controlled by GRP78 expression on T cells

Lack of targetable antigens is a key limitation for developing successful T cell-based immunotherapies. Members of the unfolded protein response (UPR) represent ideal immunotherapy targets because the UPR regulates the ability of cancer cells to resist cell death, sustain proliferation, and metastasize. Glucose-regulated protein 78 (GRP78) is a key UPR regulator that is overexpressed and translocated to the cell surface of a wide variety of cancers in response to elevated endoplasmic reticulum (ER) stress. We show that GRP78 is highly expressed on the cell surface of multiple solid and brain tumors, making cell surface GRP78 a promising chimeric antigen receptor (CAR) T cell target. We demonstrate that GRP78-CAR T cells can recognize and kill GRP78+ brain and solid tumors in vitro and in vivo. Additionally, our findings demonstrate that GRP78 is upregulated on CAR T cells upon T cell activation; however, this expression is tumor-cell-line specific and results in heterogeneous GRP78-CAR T cell therapeutic response.

A computational and laboratory approach for the investigation of interactions of peptide conjugated natural terpenes with EpHA2 receptor

CONTEXT

Ephrin type A receptor 2 (EphA2) is a well-known drug target for cancer treatment due to its overexpression in numerous types of cancers. Thus, it is crucial to determine the binding interactions of this receptor with both the ligand-binding domain (LBD) and the kinase-binding domain (KBD) through a targeted approach in order to modulate its activity. In this work, natural terpenes with inherent anticancer properties were conjugated with short peptides YSAYP and SWLAY that are known to bind to the LBD of EphA2 receptor. We examined the binding interactions of six terpenes (maslinic acid, levopimaric acid, quinopimaric acid, oleanolic, polyalthic, and hydroxybetulinic acid) conjugated to the above peptides with the ligand-binding domain (LBD) of EphA2 receptor computationally. Additionally, following the "target-hopping approach," we also examined the interactions of the conjugates with the KBD. Our results indicated that most of the conjugates showed higher binding interactions with the EphA2 kinase domain compared to LBD. Furthermore, the binding affinities of the terpenes increased upon conjugating the peptides with the terpenes. In order to further investigate the specificity toward EphA2 kinase domain, we also examined the binding interactions of the terpenes conjugated to VPWXE (x = norleucine), as VPWXE has been shown to bind to other RTKs. Our results indicated that the terpenes conjugated to SWLAY in particular showed high efficacy toward binding to the KBD. We also designed conjugates where in the peptide portion and the terpenes were separated by a butyl (C4) group linker to examine if the binding interactions could be enhanced. Docking studies showed that the conjugates with linkers had enhanced binding with the LBD compared to those without linkers, though binding remained slightly higher without linkers toward the KBD. As a proof of concept, maslinate and oleanolate conjugates of each of the peptides were then tested with F98 tumor cells which are known to overexpress EphA2 receptor. Results indicated that the oleanolate-amido-SWLAY conjugates were efficacious in reducing the cell proliferation of the tumor cells and may be potentially developed and further studied for targeting tumor cells overexpressing the EphA2 receptor. To test if these conjugates could bind to the receptor and potentially function as kinase inhibitors, we conducted SPR analysis and ADP-Glo assay. Our results indicated that OA conjugate with SWLAY showed the highest inhibition.

METHODS

Docking studies were carried out using AutoDock Vina, v.1.2.0; Molecular Dynamics and MMGBSA calculations were carried out through Schrodinger Software DESMOND.

Identification of cancer protein biomarker based on cell specific peptide and its potential role in predicting tumor metastasis

The identification of tumor related membrane protein is important for both cancer diagnosis and targeted therapy. Currently, the number of ideal clinical biomarkers is still limited partially because of lacking efficient methods in biomarker discovery. Targeting peptides are generated by library screening and can recognize their cognate targets with high specificity and affinity. In addition, these functional peptides have been considered to be a valuable molecule for both imaging detection and targeting therapy in oncology. The selected peptides can be used to identify cell-surface protein biomarkers of cancer cells. In our study, the peptide (VECYLIRDNLCIY) derived from the bacteria displaying library worked as a bait to capture its binding partner and aldolase A was identified as the candidate. The results indicated that aldolase A' expression level on the cell membrane was regulated by PI3K and aldolase A located on the membrane could inhibit the aggression of tumors through mediating cell metabolic pathway. Aldolase A could work as the joint for the metabolic and signal pathways related to tumor progression. In our work, we demonstrated a promising technology for selecting and identifying binding partners for cell-specific peptides that enables discovery of new tumor biomarkers, showing great scientific study values and clinical translation potencies. SIGNIFICANCE: MS-based cancer biomarker discovery provides promising target candidates for cancer diagnosis and therapy. However, the inevitable limits make it inconvenient in the process of sample preparation and data analysis. In this way, the small molecular probes show some advantages due to their readily availability and specific binding affinity such as the aptamers screened with SELEX technology and peptides derived from displaying libraries. In the present study, aldolase A was proved to be the membrane binding partner of a specific peptidic ligand towards ZR-75-1 tumor cell. It was discovered that membrane aldolase A was more sensitive and observable than other subcellular fractions in response to cellular metabolic state alteration or glucose availability. In addition, the reduced membrane-localized aldolase A expression indicated a more aggressive tumor phenotype and was accompanied by the upregulation of MMP-2/MMP-9. The non-glycolysis activity endowed it with potential utility as a tumor diagnostic marker and therapeutic target. This work demonstrates the practicability of screened peptide in cancer biomarker discovery, facilitating the development of diagnostic tools and therapeutic approaches to cancer, and markedly improves our understanding of cancer biology.

Cell-Penetrating Peptidic GRP78 Ligand-Conjugated Iron Oxide Magnetic Nanoparticles for Tumor-Targeted Doxorubicin Delivery and Imaging

Although chemotherapy is regarded as an essential option in cancer treatment, it is still far from being perfect. Inadequate tumor drug concentration and systemic toxicity along with broad biodistribution have diminished the utility of chemotherapy. Tumor-targeting peptide-conjugated multifunctional nanoplatforms have emerged as an effective strategy for site-directed tumor tissues in cancer treatment and imaging. Herein, Pep42-targeted iron oxide magnetic nanoparticles (IONPs) functionalized with β-cyclodextrin (ßCD) containing doxorubicin (DOX) (Fe₃O₄-ßCD-Pep42-DOX) were successfully developed. The physical effects of the prepared NPs were characterized by employing various techniques. Transmission electron microscopy (TEM) images disclosed that the developed Fe₃O₄-ßCD-Pep42-DOX nanoplatforms had a spherical morphology and a core-shell structure with a size of nearly 17 nm. Fourier transform infrared (FT-IR) spectroscopy showed that β-cyclodextrin, DOX, and Pep42 molecules were successfully loaded on the IONPs. In vitro cytotoxicity analysis revealed that the fabricated multifunctional Fe₃O₄-ßCD-Pep42 nanoplatforms possessed excellent biosafety toward BT-474, MDA-MB468 (cancerous cells), and MCF10A normal cells, while Fe₃O₄-ßCD-Pep42-DOX exhibited great cancer cell killing ability. The high cellular uptake along with intracellular trafficking of Fe₃O₄-ßCD-Pep42-DOX highlights the usefulness of the Pep42-targeting peptide. In vivo results strongly supported the in vitro results, i.e., significant tumor size reduction was observed by single-dose injection of Fe₃O₄-ßCD-Pep42-DOX into tumor-bearing mice. Interestingly, in vivo MR imaging (MRI) of Fe₃O₄-ßCD-Pep42-DOX revealed T₂ contrast improvement in the tumor cells and therapeutic ability in cancer theranostics. Taken together, these findings provided strong evidence for the potential capability of Fe₃O₄-ßCD-Pep42-DOX as a multifunctional nanoplatform in cancer therapy and imaging and opens up a new avenue of research in this area.

Forsythiaside A ameliorates sepsis-induced acute kidney injury via anti-inflammation and antiapoptotic effects by regulating endoplasmic reticulum stress

ETHNOPHARMACOLOGICAL RELEVANCE

Sepsis is a systemic inflammatory response syndrome caused by an infection in the body, and accompanying acute kidney injury (AKI) is a common complication of sepsis. It is associated with increased mortality and morbidity. Forsythia Fructus, the dried fruit of Forsythia suspensa (Thunb.) Vahl, is a commonly used traditional Chinese medicine.

AIMS OF THE STUDY

This study aimed to elucidate the protective effect of Forsythiaside A (FTA) on sepsis-induced AKI by downregulating inflammatory and apoptotic responses, and exploring its underlying mechanism.

METHODS

Septic AKI was induced through intraperitoneal injection of LPS (10 mg/kg) using male C57BL/6 mice and pretreated with FTA or control saline. First, we assessed the degree of renal injury by creatinine, blood urea nitrogen measurement, and HE staining of renal tissue; secondly, the inflammation and apoptosis were measured byELISA, qPCR, and TUNEL immunofluorescence; finally, the mechanism was explored by computer molecular docking and Western blot.

RESULTS

Our data showed that FTA markedly attenuated pathological kidney injuries, alleviated the elevation of serum BUN and Creatinine, suggesting the renal protective effect of FTA. Notably, FTA significantly inhibited the renal expression of proinflammatory cytokine IL-1β, IL-6, and TNF-α both at protein and mRNA levels and attenuated cell apoptosis in the kidney, as measured by caspase-3 immunoblot and TUNEL assay, indicating its anti-Inflammation and antiapoptotic properties. Mechanistically, administration of LPS resulted in robust endoplasmic reticulum (ER) stress responses in the kidney, evidenced by glucose-regulated protein 78(GRP78) upregulation, protein kinase RNA-like endoplasmic reticulum kinase (PERK) activation, eukaryotic initiation factor 2 alpha (elF2α) phosphorylation and C/EBP homologous protein (CHOP) overexpression, which could be significantly blocked by FTA pretreatment. Dynamic simulation and molecular docking were performed to provide further insight.

CONCLUSIONS

Collectively, our data suggest that FTA ameliorates sepsis-induced acute kidney injury via its anti-inflammation and antiapoptotic properties by regulating PERK signaling dependent ER stress responses.

Comparison of allosteric signaling in DnaK and BiP using mutual information between simulated residue conformations

The heat shock protein 70 kDa (Hsp70) chaperone system serves as a critical component of protein quality control across a wide range of prokaryotic and eukaryotic organisms. Divergent evolution and specialization to particular organelles have produced numerous Hsp70 variants which share similarities in structure and general function, but differ substantially in regulatory aspects, including conformational dynamics and activity modulation by cochaperones. The human Hsp70 variant BiP (also known as GRP78 or HSPA5) is of therapeutic interest in the context of cancer, neurodegenerative diseases, and viral infection, including for treatment of the pandemic virus SARS-CoV-2. Due to the complex conformational rearrangements and high sequential variance within the Hsp70 protein family, it is in many cases poorly understood which amino acid mutations are responsible for biochemical differences between protein variants. In this study, we predicted residues associated with conformational regulation of human BiP and Escherichia coli DnaK. Based on protein structure networks obtained from molecular dynamics simulations, we analyzed the shared information between interaction timelines to highlight residue positions with strong conformational coupling to their environment. Our predictions, which focus on the binding processes of the chaperone's substrate and cochaperones, indicate residues filling potential signaling roles specific to either DnaK or BiP. By combining predictions of individual residues into conformationally coupled chains connecting ligand binding sites, we predict a BiP specific secondary signaling pathway associated with substrate binding. Our study sheds light on mechanistic differences in signaling and regulation between Hsp70 variants, which provide insights relevant to therapeutic applications of these proteins.

Peptides as Pharmacological Carriers to the Brain: Promises, Shortcomings and Challenges

Central nervous system (CNS) diseases are among the most difficult to treat, mainly because the vast majority of the drugs fail to cross the blood-brain barrier (BBB) or to reach the brain at concentrations adequate to exert a pharmacological activity. The obstacle posed by the BBB has led to the in-depth study of strategies allowing the brain delivery of CNS-active drugs. Among the most promising strategies is the use of peptides addressed to the BBB. Peptides are versatile molecules that can be used to decorate nanoparticles or can be conjugated to drugs, with either a stable link or as pro-drugs. They have been used to deliver to the brain both small molecules and proteins, with applications in diverse therapeutic areas such as brain cancers, neurodegenerative diseases and imaging. Peptides can be generally classified as receptor-targeted, recognizing membrane proteins expressed by the BBB microvessels (e.g., Angiopep2, CDX, and iRGD), "cell-penetrating peptides" (CPPs; e.g. TAT_47-57, SynB1/3, and Penetratin), undergoing transcytosis through unspecific mechanisms, or those exploiting a mixed approach. The advantages of peptides have been extensively pointed out, but so far few studies have focused on the potential negative aspects. Indeed, despite having a generally good safety profile, some peptide conjugates may display toxicological characteristics distinct from those of the peptide itself, causing for instance antigenicity, cardiovascular alterations or hemolysis. Other shortcomings are the often brief lifetime in vivo, caused by the presence of peptidases, the vulnerability to endosomal/lysosomal degradation, and the frequently still insufficient attainable increase of brain drug levels, which remain below the therapeutically useful concentrations. The aim of this review is to analyze not only the successful and promising aspects of the use of peptides in brain targeting but also the problems posed by this strategy for drug delivery.

Chimeric Antigen Receptor T Cells Targeting Cell Surface GRP78 to Eradicate Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a serious, life-threatening hematological malignancy. The treatment outcome of relapsed or refractory AML patients remains dismal, and new treatment options are needed. Chimeric antigen receptor (CAR) T cells have been successful in improving the prognosis for B-lineage acute lymphoblastic leukemia and lymphoma by targeting CD19. However, CAR T-cell therapy for AML is still elusive, owing to the lack of a tumor-specific cell surface antigen and spare hematopoietic stem cells (HSCs). This study generated a novel CAR construction that targets the cell surface protein glucose-regulated protein 78 (GRP78) (csGRP78). We confirmed that GRP78-CAR T cells demonstrate an anti-tumor effect against human AML cells in vitro. In xenograft models, GRP78-CAR T cells effectively eliminate AML cells and protect mice against systemic leukemia, in the meanwhile, prolonging survival. In addition, GRP78-CAR T cells also specifically eradicate the primary AML patient-derived blast. In particular, GRP78-CAR T cells spare normal HSCs, highlighting that GRP78-CAR is a promising approach for the therapy of AML.

Interference of Chaga mushroom terpenoids with the attachment of SARS-CoV-2; in silico perspective

Finding a potent inhibitor to the pandemic SARS-CoV-2 is indispensable nowadays. Currently, in-silico methods work as expeditious investigators to screen drugs for possible repurposing or design new ones. Targeting one of the possible SARS-CoV-2 attachment and entry receptors, Glucose-regulated protein 78 (GRP78), is an approach of major interest. Recently, GRP78 was reported as a recognized representative in recognition of the latest variants of SARS-CoV-2. In this work, molecular docking and molecular dynamics simulations were performed on the host cell receptor GRP78. With its many terpenoid compounds, Chaga mushroom was tested as a potential therapeutic against the SARS-CoV-2 receptor, GRP78. Results revealed low binding energies (high affinities) toward the GRP78 substrate-binding domain β (SBDβ) of Chaga mushroom terpenoids. Even the highly specific cyclic peptide Pep42, which selectively targeted GRP78 over cancer cells in vivo, showed lower binding affinity against GRP78 SBDβ compared to the binding affinities of terpenoids. These are auspicious results that need to be tested experimentally. Intriguingly, terpenoids work as a double sword as they can be used to interfere with VUI 202,012/01, 501.V2, and B.1.1.248 variants of SARS-CoV-2 spike recognition.

Healthy humans can be a source of antibodies countering COVID-19

Here, we describe the isolation of 18 unique anti SARS-CoV-2 human single-chain antibodies from an antibody library derived from healthy donors. The selection used a combination of phage and yeast display technologies and included counter-selection strategies meant to direct the selection of the receptor-binding motif (RBM) of SARS-CoV-2 spike protein's receptor binding domain (RBD2). Selected antibodies were characterized in various formats including IgG, using flow cytometry, ELISA, high throughput SPR, and fluorescence microscopy. We report antibodies' RBD2 recognition specificity, binding affinity, and epitope diversity, as well as ability to block RBD2 binding to the human receptor angiotensin-converting enzyme 2 (ACE2) and to neutralize authentic SARS-CoV-2 virus infection in vitro. We present evidence supporting that: 1) most of our antibodies (16 out of 18) selectively recognize RBD2; 2) the best performing 8 antibodies target eight different epitopes of RBD2; 3) one of the pairs tested in sandwich assays detects RBD2 with sub-picomolar sensitivity; and 4) two antibody pairs inhibit SARS-CoV-2 infection at low nanomolar half neutralization titers. Based on these results, we conclude that our antibodies have high potential for therapeutic and diagnostic applications. Importantly, our results indicate that readily available non immune (naïve) antibody libraries obtained from healthy donors can be used to select high-quality monoclonal antibodies, bypassing the need for blood of infected patients, and offering a widely accessible and low-cost alternative to more sophisticated and expensive antibody selection approaches (e.g. single B cell analysis and natural evolution in humanized mice).

Redesigning of Cell-Penetrating Peptides to Improve Their Efficacy as a Drug Delivery System

Cell-penetrating peptides (CPP) are promising tools for the transport of a broad range of compounds into cells. Since the discovery of the first members of this peptide family, many other peptides have been identified; nowadays, dozens of these peptides are known. These peptides sometimes have very different chemical–physical properties, but they have similar drawbacks; e.g., non-specific internalization, fast elimination from the body, intracellular/vesicular entrapment. Although our knowledge regarding the mechanism and structure–activity relationship of internalization is growing, the prediction and design of the cell-penetrating properties are challenging. In this review, we focus on the different modifications of well-known CPPs to avoid their drawbacks, as well as how these modifications may increase their internalization and/or change the mechanism of penetration.

Novel Synovial Targeting Peptide-Sinomenine Conjugates as a Potential Strategy for the Treatment of Rheumatoid Arthritis

Sinomenine (SIN) is an effective anti-inflammatory agent, but its therapeutic efficacy is limited by its short half-life and the high dosage required. Tissue-specific strategies have the potential to overcome these limitations. The synovial homing peptide (CKSTHDRLC) was identified to have high synovial endothelium targeting affinity. In this work, two peptide-drug conjugates (PDCs), conjugate (L) and conjugate (C), were synthesized, in which SIN was covalently connected to the linear and cyclic synovial homing peptide, respectively, via a 6-aminocaproic acid linker. An evaluation of biostability showed that conjugate (C) was more stable in mouse serum and inflammatory joint homogenate than conjugate (L). The two conjugates gradually released free SIN. Interestingly, conjugate (L) self-cyclized via a disulfide bridge in a biological environment, which significantly impacted its biostability. It had an almost equipotent half-life in serum but faster degradation in the inflammatory joint than conjugate (C). Therefore, conjugate (C) exhibited better therapeutic efficacy and tissue targeting. All the results indicated that PDCs particularly in its cyclic form might be more efficient for targeted deliver and represent a potential strategy for the treatment of rheumatoid arthritis.

The development of peptide-drug conjugates (PDCs) strategies for paclitaxel

INTRODUCTION

Paclitaxel is a powerful and effective anti-tumor drug with wide clinical application. However, there are still some limitations, including poor water solubility, low specificity, and susceptibility to drug resistance. The peptide-drug conjugates (PDCs) represent a rising class of therapeutic drugs, which combines small-molecule chemotherapeutic drugs with highly flexible peptides through a cleavable or non-cleavable linker. When this strategy is applied, the therapeutic effects of paclitaxel can be improved.

AREAS COVERED

In this review, we discuss the application of the PDCs strategy in paclitaxel, including two parts: the tumor targeting peptide-paclitaxel conjugates and the cell penetrating peptide-paclitaxel conjugates.

EXPERT OPINION

Combining drugs with multifunctional peptides covalently is an effective strategy for delivering paclitaxel to tumors. Depending on different functional peptides, conjugates can increase the water solubility of paclitaxel, tumor permeability of paclitaxel, the accumulation of paclitaxel in tumor tissues, and enhance the antitumor effect of paclitaxel. In addition, due to the change of cell entry mechanism, partial conjugates can restore the therapeutic activity of paclitaxel against resistant tumors. Notably, in order to better translate into the clinical field in the future, more research should be conducted to ensure the safety and effectiveness of peptide-paclitaxel conjugates.

CAR T cells redirected to cell surface GRP78 display robust anti-acute myeloid leukemia activity and do not target hematopoietic progenitor cells

Developing CAR T cells for acute myeloid leukemia (AML) has been hampered by a paucity of targets that are expressed on AML blasts and not on hematopoietic progenitor cells (HPCs). Here we demonstrate that GRP78 is expressed on the cell surface of primary AML blasts but not HPCs. To target GRP78, we generate T cell expressing a GRP78-specific peptide-based CAR, which show evidence of minimal fratricide post activation/transduction and antigen-dependent T cell differentiation. GRP78-CAR T cells recognize and kill GRP78-positive AML cells without toxicity to HPCs. In vivo, GRP78-CAR T cells have significant anti-AML activity. To prevent antigen-dependent T cell differentiation, we block CAR signaling and GRP78 cell surface expression post activation by using dasatinib during GRP78-CAR T cell manufacturing. This significantly improves their effector function in vitro and in vivo. Thus, targeting cell surface GRP78-positive AML with CAR T cells is feasible, and warrants further active exploration.

Host factors: Implications in immunopathogenesis of COVID-19

Coronavirus disease 2019 (COVID-19) is a viral disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). COVID-19 is more serious in people with underlying diseases, but the cause of healthy people with progressive disease is largely unknown. Host genetic factors such as ACE2 variants, IFITM-3, HLA, TMRSS2, and furin polymorphisms appear to be one of the agents involved in the progression of the COVID-19 and outcome of the disease. This review discusses the general characteristics of SARS-CoV-2, including viral features, receptors, cell entry, clinical findings, and the main human genetic factors that may contribute to the pathogenesis of COVID-19 and get the patients' situation more complex. Further knowledge in this context may help to find a way to prevent and treat this viral pneumonia.

GRP78: A possible relationship of COVID-19 and the mucormycosis; in silico perspective

Mucormycosis is a severe fungal infection reported in many cancer survivors, diabetic and immune-suppressed patients during organ transplants. A vast spark in the reported COVID-19 cases is noticed in India during the second wave in May 2021, when Mucormycosis is declared an epidemic. Despite being a rare disease, the mortality rate associated with Mucormycosis is more than 40%. Spore coat proteins (CotH) are essential proteins in many pathogenic bacteria and fungi. CotH3 was reported as the vital protein required for fungal virulence in Mucormycosis. We previously reported the involvement of the host cell-surface receptor GRP78 in SARS-CoV-2 spike recognition. Additionally, GRP78 is known to be the virulence factor during Mucormycosis. Using state-of-the-art structural bioinformatics and molecular modeling tools, we predicted the GRP78 binding site to the Rhizopus delemar CotH3 protein. Our findings pave the way toward rationally designing small molecule inhibitors targeting the GRP78 and its counter proteins in both pathogenic viral (SARS-CoV-2 spike) and fungal (R. delemar CotH3) diseases.

A Review of Human Coronaviruses' Receptors: The Host-Cell Targets for the Crown Bearing Viruses

A novel human coronavirus prompted considerable worry at the end of the year 2019. Now, it represents a significant global health and economic burden. The newly emerged coronavirus disease caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the primary reason for the COVID-19 global pandemic. According to recent global figures, COVID-19 has caused approximately 243.3 million illnesses and 4.9 million deaths. Several human cell receptors are involved in the virus identification of the host cells and entering them. Hence, understanding how the virus binds to host-cell receptors is crucial for developing antiviral treatments and vaccines. The current work aimed to determine the multiple host-cell receptors that bind with SARS-CoV-2 and other human coronaviruses for the purpose of cell entry. Extensive research is needed using neutralizing antibodies, natural chemicals, and therapeutic peptides to target those host-cell receptors in extremely susceptible individuals. More research is needed to map SARS-CoV-2 cell entry pathways in order to identify potential viral inhibitors.

Filamentous Bacteriophage-A Powerful Carrier for Glioma Therapy

Glioma is a life-threatening malignant tumor. Resistance to traditional treatments and tumor recurrence present major challenges in treating and managing this disease, consequently, new therapeutic strategies must be developed. Crossing the blood-brain barrier (BBB) is another challenge for most drug vectors and therapy medications. Filamentous bacteriophage can enter the brain across the BBB. Compared to traditional drug vectors, phage-based drugs offer thermodynamic stability, biocompatibility, homogeneity, high carrying capacity, self-assembly, scalability, and low toxicity. Tumor-targeting peptides from phage library and phages displaying targeting peptides are ideal drug delivery agents. This review summarized recent studies on phage-based glioma therapy and shed light on the developing therapeutics phage in the personalized treatment of glioma.

Source and exploration of the peptides used to construct peptide-drug conjugates

Peptide-drug conjugates (PDCs) are a class of novel molecules widely designed and synthesized for delivering payload drugs. The peptide part plays a vital role in the whole molecule, because they determine the ability of the molecules to penetrate the membrane and target to the specific targets. Here, we introduce the source of different kinds of cell-penetrating peptides (CPPs) and cell-targeting peptides (CTPs) that have been used or could be used in constructing PDCs as well as their latest application in delivering drugs. What's more, the approaches of developing CPPs and CTPs and the techniques to discover novel peptides are focused on and summarized in the review. This review aims to help relevant researchers fast understand the research status of peptides in PDCs and carry forward the process of novel peptides discovery.

Natural products may interfere with SARS-CoV-2 attachment to the host cell

SARS-CoV-2 has been emerged in December 2019 in China, causing deadly (5% mortality) pandemic pneumonia, termed COVID-19. More than one host-cell receptor is reported to be recognized by the viral spike protein, among them is the cell-surface Heat Shock Protein A5 (HSPA5), also termed GRP78 or BiP. Upon viral infection, HSPA5 is upregulated, then translocating to the cell membrane where it is subjected to be recognized by the SARS-CoV-2 spike. In this study, some natural product compounds are tested against the HSPA5 substrate-binding domain β (SBDβ), which reported to be the recognition site for the SARS-CoV-2 spike. Molecular docking and molecular dynamics simulations are used to test some natural compounds binding to HSPA5 SBDβ. The results show high to a moderate binding affinity for the phytoestrogens (Diadiazin, Genistein, Formontein, and Biochanin A), chlorogenic acid, linolenic acid, palmitic acid, caffeic acid, caffeic acid phenethyl ester, hydroxytyrosol, cis-p-Coumaric acid, cinnamaldehyde, thymoquinone, and some physiological hormones such as estrogens, progesterone, testosterone, and cholesterol to the HSPA5 SBDβ. Based on its binding affinities, the phytoestrogens and estrogens are the best in binding HSPA5, hence may interfere with SARS-CoV-2 attachment to the stressed cells. These compounds can be successful as anti-COVID-19 agents for people with a high risk of cell stress like elders, cancer patients, and front-line medical staff.Communicated by Ramaswamy H. Sarma.

Is There any Alternative Receptor for SARS-CoV-2?

Angiotensin-converting enzyme II (ACE2) in association with type II transmembrane serine protease (TMPRSS2) is considered the main receptor of SARS-CoV-2. However, considering the clinical complications of COVID-19 in different organs, there is no strong association between the abundance of ACE2/TMPRSS2 co-expression and clinical features of the disease and the severity of complications. Since SARS-CoV-2 affects certain organs that lack or have low expression of ACE2/TMPRSS2, it may be possible that the virus employs other receptors for colonization and entry. Based on recent studies, glucose-regulated protein 78 (GRP78) can be a potential alternative receptor for SARS-CoV-2 entry. In this letter, supporting evidence proposed GRP78 as an alternative receptor in SARS-CoV-2 infection.

Synthetic Antibody Mimics Based on Cancer-Targeting Immunostimulatory Peptides

De novo cancer-targeting immunostimulatory peptides have been designed and developed as synthetic antibody mimics. A series of bifunctional peptides incorporating NKp30-binding and NK-cell-activating domains were synthesized as linear dimers and then extended into branching trimeric peptides by the incorporation of GRP78-targeting and tumor-cell-binding sequences. A selected trimeric peptide from this small set of peptides displayed binding capabilities on GRP78+ HepG2 and A549 target cells. Cell binding diminished in the presence of an anti-GRP78 peptide blocker, thus suggesting GRP78-binding dependence. Similarly, the selected trimeric peptide was also found to exhibit NK cell binding in an NKp30-dependent manner, which translated into NK cell activation as indicated by cytokine secretion. In co-culture, fluorescence microscopy revealed that the target GFP-expressing A549 cells were visibly associated with the effector NK cells when pre-activated with lead trimeric peptide. Accordingly, A549 cells were found to be compromised, as evidenced by the loss of GFP signal and notable detection of early-/late-stage apoptosis. Investigation of the immunological markers related to toxicity revealed detectable secretion of pro-inflammatory cytokines and chemokines, including IFN-γ, TNF-α, and IL-8. Furthermore, administration of peptide-activated NK cells into A549-tumor-bearing mice resulted in a consistent decrease in tumor growth when compared to the untreated control group. Taken together, the identification of a lead trimeric peptide capable of targeting and activating NK cells' immunotoxicity directly towards GRP78+ /B7H6- tumors provides a novel proof-of-concept for the development of cancer-targeting immunostimulatory peptide ligands that mimic antibody-targeting and -activating functions related to cancer immunotherapy applications.

GRP78 in lung cancer

Glucose-regulating protein 78 (GRP78) is a molecular chaperone in the endoplasmic reticulum (ER) that promotes folding and assembly of proteins, controls the quality of proteins, and regulates ER stress signaling through Ca²⁺ binding to the ER. In tumors, GRP78 is often upregulated, acting as a central stress sensor that senses and adapts to changes in the tumor microenvironment, mediating ER stress of cancer cells under various stimulations of the microenvironment to trigger the folding protein response. Increasing evidence has shown that GRP78 is closely associated with the progression and poor prognosis of lung cancer, and plays an important role in the treatment of lung cancer. Herein, we reviewed for the first time the functions and mechanisms of GRP78 in the pathological processes of lung cancer, including tumorigenesis, apoptosis, autophagy, progression, and drug resistance, giving a comprehensive understanding of the function of GRP78 in lung cancer. In addition, we also discussed the potential role of GRP78 as a prognostic biomarker and therapeutic target for lung cancer, which is conducive to improving the assessment of lung cancer and the development of new therapeutic interventions.

In silico identification of available drugs targeting cell surface BiP to disrupt SARS-CoV-2 binding and replication: Drug repurposing approach

Aims

Cell surface binding immunoglobin protein (csBiP) is predicted to be susceptible to SARS-CoV-2 binding. With a substrate-binding domain (SBD) that binds to polypeptides and a nucleotide-binding domain (NBD) that can initiate extrinsic caspase-dependent apoptosis, csBiP may be a promising therapeutic target for COVID-19. This study aims to identify FDA-approved drugs that can neutralize viral binding and prevent viral replication by targeting the functional domains of csBiP.

Methods

In silico screening of 1999 FDA-approved drugs against the functional domains of BiP were performed using three molecular docking programs to avoid bias from individual docking programs. Top ligands were selected by averaging the ligand rankings from three programs. Interactions between top ligands and functional domains of BiP were analyzed.

Key findings

The top 10 SBD-binding candidates are velpatasvir, irinotecan, netupitant, lapatinib, doramectin, conivaptan, fenoverine, duvelisib, irbesartan, and pazopanib. The top 10 NBD-binding candidates are nilotinib, eltrombopag, grapiprant, topotecan, acetohexamide, vemurafenib, paritaprevir, pixantrone, azosemide, and piperaquine-phosphate. Among them, Velpatasvir and paritaprevir are antiviral agents that target the protease of hepatitis C virus. Netupitant is an anti-inflammatory drug that inhibits neurokinin-1 receptor, which contributes to acute inflammation. Grapiprant is an anti-inflammatory drug that inhibits the prostaglandin E₂ receptor protein subtype 4, which is expressed on immune cells and triggers inflammation. These predicted SBD-binding drugs could disrupt SARS-CoV-2 binding to csBiP, and NBD-binding drugs may falter viral attachment and replication by locking the SBD in closed conformation and triggering apoptosis in infected cells.

Significance

csBiP appears to be a novel therapeutic target against COVID-19 by preventing viral attachment and replication. These identified drugs could be repurposed to treat COVID-19 patients.

Evaluation and characterization of HSPA5 (GRP78) expression profiles in normal individuals and cancer patients with COVID-19

HSPA5 (BiP, GRP78) has been reported as a potential host-cell receptor for SARS-Cov-2, but its expression profiles on different tissues including tumors, its susceptibility to SARS-Cov-2 virus and severity of its adverse effects on malignant patients are unclear. In the current study, HSPA5 has been found to be expressed ubiquitously in normal tissues and significantly increased in 14 of 31 types of cancer tissues. In lung cancer, mRNA levels of HSPA5 were 253-fold increase than that of ACE2. Meanwhile, in both malignant tumors and matched normal samples across almost all cancer types, mRNA levels of HSPA5 were much higher than those of ACE2. Higher expression of HSPA5 significantly decreased patient overall survival (OS) in 7 types of cancers. Moreover, systematic analyses found that 7.15% of 5,068 COVID-19 cases have malignant cancer coincidental situations, and the rate of severe events of COVID-19 patients with cancers present a higher trend than that for all COVID-19 patients, showing a significant difference (33.33% vs 16.09%, p<0.01). Collectively, these data imply that the tissues with high HSPA5 expression, not low ACE2 expression, are susceptible to be invaded by SARS-CoV-2. Taken together, this study not only indicates the clinical significance of HSPA5 in COVID-19 disease and cancers, but also provides potential clues for further medical treatments and managements of COVID-19 patients.

Antibody-drug conjugates: an evolving approach for melanoma treatment

Melanoma continues to be an aggressive and deadly form of skin cancer while therapeutic options are continuously developing in an effort to provide long-term solutions for patients. Immunotherapeutic strategies incorporating antibody-drug conjugates (ADCs) have seen varied levels of success across tumor types and represent a promising approach for melanoma. This review will explore the successes of FDA-approved ADCs to date compared to the ongoing efforts of melanoma-targeting ADCs. The challenges and opportunities for future therapeutic development are also examined to distinguish how ADCs may better impact individuals with malignancies such as melanoma.

COVID-19 and Cell Stress

The present century will undoubtedly be marked with the COVID-19 global health crisis. It is not time yet to talk about the total number of deaths and hospitalizations, as they are enormously growing daily. Understanding the nature of COVID-19-induced pneumonia is vital in order to deal with the associated health complications. Cell stress is an established mechanism known to be associated with infection and cancer. Different proteins crucial for cellular response to stress are reported to be a possible target to stop the infection and to reduce the chemo-resistance in cancer. Heat shock protein (HSP) families of chaperones play an essential role in cells both in normal state and under stress. The upregulation of HSP5A, also termed GRP78 or Bip, is reported in different viral infections. This chapter introduces the current knowledge about severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has caused the COVID-19 pandemic, and cell stress aimed at defining possible strategies to combat the COVID-19 pandemic.

SARS-CoV-2 Spike-Heat Shock Protein A5 (GRP78) Recognition may be Related to the Immersed Human Coronaviruses

The human coronavirus (HCoV), SARS-CoV-2, caused more than 34 M confirmed infections from which more than 1 M deaths are reported until now (the WHO situation report-154). The current pandemic causes severe socio-economic burden. Due to the importance of understanding of the mode of recognition and viral entry, spike protein shed drug designers as the first look protein target with the first released solved structure on 26 February 2020 (PDB ID: 6VSB). It is proposed that the recognition site for GRP78 is found in SARS-CoV-2 and the immersed human coronaviruses but experimental validation is still required.

Geranii Herba as a Potential Inhibitor of SARS-CoV-2 Main 3CLpro, Spike RBD, and Regulation of Unfolded Protein Response: An In Silico Approach

Background: Since the first patient identified with SARS-CoV-2 symptoms in December 2019, the trend of a spreading coronavirus disease 2019 (COVID-19) infection has remained to date. As for now, there is an urgent need to develop novel drugs or vaccines for the SARS-CoV-2 virus. Methods: Polyphenolic compounds have potential as drug candidates for various diseases, including viral infections. In this study, polyphenolic compounds contained in Geranii Herba were chosen for an in silico approach. The SARS-CoV-2 receptor-binding domain (RBD), 3CL^pro (Replicase polyprotein 1ab), and the cell surface receptor glucose-regulated protein 78 (GRP78) were chosen as target proteins. Results: Based on the molecular docking analysis, ellagic acid, gallic acid, geraniin, kaempferitrin, kaempferol, and quercetin showed significant binding interactions with the target proteins. Besides, the molecular dynamic simulation studies support Geranii Herba’s inhibition efficiency on the SARS-CoV-2 RBD. We assume that the active compounds in Geranii Herba might inhibit SARS-CoV-2 cell entry through the ACE2 receptor and inhibit the proteolytic process. Besides, these compounds may help to regulate the cell signaling under the unfolded protein response in endoplasmic reticulum stress through the binding with GRP78 and avoid the SARS-CoV-2 interaction. Conclusions: Hence, the compounds present in Geranii Herba could be used as possible drug candidates for the prevention/treatment of SARS-CoV-2 infection.

Human papillomavirus E6: Host cell receptor, GRP78, binding site prediction

Human papillomavirus (HPV) is the main cervical cancer-promoting element that is transmitted through sexual routes. Anal, head, and throat cancers are also reported to be accompanied by HPV infection. E6 is one of the HPV nonstructural proteins, which is responsible for cell differentiation by targeting tumor suppressor genes, p105Rb and p53. E6 was reported to be stabilized by two chaperone proteins; glucose-regulated protein 78 (GRP78) and heat shock protein 90. GRP78 is responsible for the unfolded protein response of the cells, and it was reported to be upregulated in many cancers, including cervical cancer. It was reported that knocking out GRP78 destabilizes E6 leading to faster degradation of E6 in vivo. The current work predicts the possible binding mode between E6 and GRP78 based on sequence and structural similarities.

Development of Anti-Yersinia pestis Human Antibodies with Features Required for Diagnostic and Therapeutic Applications

BACKGROUND

Yersinia pestis is a category A infective agent that causes bubonic, septicemic, and pneumonic plague. Notably, the acquisition of antimicrobial or multidrug resistance through natural or purposed means qualifies Y. pestis as a potential biothreat agent. Therefore, high-quality antibodies designed for accurate and sensitive Y. pestis diagnostics, and therapeutics potentiating or replacing traditional antibiotics are of utmost need for national security and public health preparedness.

METHODS

Here, we describe a set of human monoclonal immunoglobulins (IgG1s) targeting Y. pestis fraction 1 (F1) antigen, previously derived from in vitro evolution of a phage-display library of single-chain antibodies (scFv). We extensively characterized these antibodies and their effect on bacterial and mammalian cells via: ELISA, flow cytometry, mass spectrometry, spectroscopy, and various metabolic assays.

RESULTS

Two of our anti-F1 IgG (αF1Ig 2 and αF1Ig 8) stood out for high production yield, specificity, and stability. These two antibodies were additionally attractive in that they displayed picomolar affinity, did not compete when binding Y. pestis, and retained immunoreactivity upon chemical derivatization. Most importantly, these antibodies detected <1,000 Y. pestis cells in sandwich ELISA, did not harm respiratory epithelial cells, induced Y. pestis agglutination at low concentration (350 nM), and caused apparent reduction in cell growth when radiolabeled at a nonagglutinating concentration (34 nM).

CONCLUSION

These antibodies are amenable to the development of accurate and sensitive diagnostics and immuno/radioimmunotherapeutics.

ACE2: Evidence of role as entry receptor for SARS-CoV-2 and implications in comorbidities

Pandemic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus 19 disease (COVID-19) which presents a large spectrum of manifestations with fatal outcomes in vulnerable people over 70-years-old and with hypertension, diabetes, obesity, cardiovascular disease, COPD, and smoking status. Knowledge of the entry receptor is key to understand SARS-CoV-2 tropism, transmission and pathogenesis. Early evidence pointed to angiotensin-converting enzyme 2 (ACE2) as SARS-CoV-2 entry receptor. Here, we provide a critical summary of the current knowledge highlighting the limitations and remaining gaps that need to be addressed to fully characterize ACE2 function in SARS-CoV-2 infection and associated pathogenesis. We also discuss ACE2 expression and potential role in the context of comorbidities associated with poor COVID-19 outcomes. Finally, we discuss the potential co-receptors/attachment factors such as neuropilins, heparan sulfate and sialic acids and the putative alternative receptors, such as CD147 and GRP78.

GRP78 targeting: Hitting two birds with a stone

BACKGROUND

Glucose regulating protein 78 (GRP78) is one member of the Heat Shock Protein family of chaperone proteins (HSPA5) found in eukaryotes. It acts as the master of the Unfolded Protein Response (UPR) process in the lumen of the Endoplasmic Reticulum (ER).

SCOPE

Under the stress of unfolded proteins, GRP78 binds to the unfolded proteins to prevent misfolding, while under the load of the unfolded protein, it drives the cell to autophagy or apoptosis. Several attempts reported the overexpression of GRP78 on the cell membrane of cancer cells and cells infected with viruses or fungi.

MAJOR CONCLUSIONS

Cell-surface GRP78 is used as a cancer cell target in previous studies. Additionally, GRP78 is used as a drug target to stop the progression of cancer cells by different compounds, including peptides, antibodies, and some natural compounds. Additionally, it can be used as a protein target to reduce the infectivity of different viruses, including the pandemic SARS-CoV-2. Besides, GRP78 targeting is used in diagnosis and imaging modalities using radionuclides.

GENERAL SIGNIFICANCE

This review summarizes the various attempts that used GRP78 both in therapy (fighting cancer, viral and fungal infections) and diagnosis (imaging).

Computer-aided drug design against spike glycoprotein of SARS-CoV-2 to aid COVID-19 treatment

BACKGROUND

SARS-CoV-2 has the Spike glycoprotein (S) which is crucial in attachment with host receptor and cell entry leading to COVID-19 infection. The current study was conducted to explore drugs against Receptor Binding Domain (RBD) of SARS-CoV-2 using in silico pharmacophore modelling and virtual screening approach to combat COVID-19.

METHODS

All the available sequences of RBD in NCBI were retrieved and multiple aligned to get insight into its diversity. The 3D structure of RBD was modelled and the conserved region was used as a template to design pharmacophore using LigandScout. Lead compounds were screened using Cambridge, Drugbank, ZINC and TIMBLE databases and these identified lead compounds were screened for their toxicity and Lipinski's rule of five. Molecular docking of shortlisted lead compounds was performed using AutoDock Vina and interacting residues were visualized.

RESULTS

Active residues of Receptor Binding Motif (RBM) in S, involved in interaction with receptor, were found to be conserved in all 483 sequences. Using this RBM motif as a pharmacophore a total of 1327 lead compounds were predicted initially from all databases, however, only eight molecules fit the criteria for safe oral drugs. Conclusion: The RBM region of S interacts with Angiotensin Converting Enzyme 2 (ACE2) receptor and Glucose Regulated Protein 78 (GRP78) to mediate viral entry. Based on in silico analysis, the lead compounds scrutinized herewith interact with S, hence, can prevent its internalization in cell using ACE2 and GRP78 receptor.The compounds predicted in this study are based on rigorous computational analysis and the evaluation of predicted lead compounds can be promising in experimental studies.

Engineered Bacteriophage T7 as a Potent Anticancer Agent in vivo

Oncolytic viruses (OVs) induce antitumor effect by both direct lysis of target cells and eliciting immunogenic response to the virus and ultimately to the target cells. These viruses are usually natural human pathogens. Bacteriophages are natural pathogens of bacteria that do not infect human and have greater advantages in safety, manipulation, and production over human viruses. We constructed an engineered bacteriophage T7 displaying a peptide, which targets murine melanoma cells and harbors a mammalian expression cassette of the cytokine granulocyte macrophage-colony stimulating factor (GM-CSF) in viral genomic DNA. The engineered phage was successfully transduced to B16F10 melanoma cells both in vitro and in vivo. GM-CSF was expressed from the transduced phage DNA. All mice treated with the phage intravenously survived for 25 days until the end of experiment, while only 40% of those not treated survived. During the 16 days of phage treatment, phage T7 displaying homing peptide and expressing GM-CSF inhibited tumor growth by 72% compared to the untreated control. Serum cytokine levels of IL-1α, TNF-α, and GM-CSF were seen to increase during the treatment. Immunohistochemical analysis of tumor tissue revealed infiltration by macrophages, dendritic cells (DCs), and CD8⁺ T cells. Migration of murine macrophages to bacteriophages was also observed in in vitro transwell assays in both time- and dose-dependent manners. Taken together, the recombinant bacteriophage T7 efficiently inhibited tumor growth by changing the tumor microenvironment and recruiting anti-tumor immune cells.

Cell surface GRP78 signaling: An emerging role as a transcriptional modulator in cancer

Cancer cells acquire dysregulated gene expression to establish specific transcriptional dependencies and their underlying mechanisms that are ultimately responsible for this addictions have not been fully elucidated. Glucose-regulated protein 78 (GRP78) is a stress-inducible, multifunctional, prosurvival, endoplasmic reticulum chaperone in the heat shock protein 70 family. Expression of cell surface GRP78 (CS-GRP78) is associated with increased malignant behavior and resistance to chemotherapy and radiotherapy by endowing various cancer cells with increased proliferative ability, altered metabolism, improved survival, and augmented invasive and metastatic potential. Emerging evidence has highlighted an unusual role of CS-GRP78 in regulating transcription factors (TFs) by mediating various signaling pathways involved in malignant transformation, metabolic reprogramming, and tumor progression. During the last decade, we targeted CS-GRP78 with C38 monoclonal antibody (C38 Mab) in numerous studies, which have highlighted the epigenetic interplay between CS-GRP78 and various TFs including c-MYC, Yes-associated protein/transcriptional coactivator with PDZ-binding motif, c-Fos, and histone acetylation to potentiate subsequent modulation of tumorigenesis, invasion, and metastasis. Here, we summarize the current state of knowledge about the role of CS-GRP78 in cancer development and progression, including epigenetic regulation and sheds light on CS-GRP78 as vulnerable target for cancer therapy. Overall, this review focuses on the mechanisms of TFs that are behind the transcriptional dysregulation in cancer and lays the groundwork for rational therapeutic use of C38 Mab based on CS-GRP78 biology.

Zika virus envelope - heat shock protein A5 (GRP78) binding site prediction

Recent studies reported the association of the Zika virus (ZIKV) with a stress response receptor on the host cell membrane that facilitates viral entry. This host receptor was the heat shock protein A5 (HSPA5), also termed glucose-regulating protein 78 (GRP78). In this study, structural bioinformatics and molecular dynamics simulations were utilized to suggest the binding site of ZIKV envelope protein during the interaction with cell-surface GRP78. The Pep42 cyclic peptide was used as a profiler, as it was reported earlier, to target GRP78 on the cancer cell membrane selectively. Sequence and structural alignments show that part of the ZIKV envelope protein (C308-C339 region), in addition to its cyclic nature, has somehow sequence and structural similarities to the cyclic Pep42. Three amino acids in the ZIKV envelope were identical to those in the Pep42 peptide. Cyclic peptides dynamics are studied, and its binding to GRP78 is predicted. Protein-protein docking is further performed to explore the binding characteristics of the ZIKV envelope to GRP78. Results revealed that the binding was favorable between ZIKV envelope protein and GRP78. The docking pose revealed the involvement of the substrate-binding domain ß of GRP78 and the domain III of the ZIKV envelope protein in viral recognition for the host-cell.