Brucella abortus induces mast cell activation through TLR-2 and TLR-4.

The Gram-negative bacteria Brucella abortus is a major cause of brucellosis in animals and humans. The host innate immune response to B. abortus is mainly associated with phagocytic cells such as dendritic cells, neutrophils, and macrophages. However, as mast cells naturally reside in the main bacterial entry sites they may be involved in bacterial recognition. At present, little is known about the role of mast cells during B. abortus infection. The role of the innate immune receptors TLR2 and TLR4 in activation of mast cells by B. abortus (strain RB51) infection was analyzed in this study. The results showed that B. abortus did not induce mast cell degranulation, but did induce the synthesis of the cytokines IL-1ß, IL-6, TNF-α, CCL3, CCL4, and CCL5. Furthermore, B. abortus stimulated key cell signaling molecules involved in mast cell activation such as p38 and NF-κB. Blockade of the receptors TLR2 and TLR4 decreased TNF-α and IL-6 release by mast cells in response to B. abortus. Taken together, our results demonstrate that mast cells are activated by B. abortus and may play a role in inducing an inflammatory response during the initial phase of the infection.

Role of CD36 in cancer progression, stemness, and targeting.

CD36 is highly expressed in diverse tumor types and its expression correlates with advanced stages, poor prognosis, and reduced survival. In cancer cells, CD36: 1) increases fatty acid uptake, reprogramming lipid metabolism; 2) favors cancer cell proliferation, and 3) promotes epithelial-mesenchymal transition. Furthermore, CD36 expression correlates with the expression of cancer stem cell markers and CD36+ cancer cells display increased stemness functional properties, including clonogenicity, chemo- and radioresistance, and metastasis-initiating capability, suggesting CD36 is a marker of the cancer stem cell population. Thus, CD36 has been pointed as a potential therapeutic target in cancer. At present, at least three different types of molecules have been developed for reducing CD36-mediated functions: blocking monoclonal antibodies, small-molecule inhibitors, and compounds that knock-down CD36 expression. Herein, we review the role of CD36 in cancer progression, its participation in stemness control, as well as the efficacy of reported CD36 inhibitors in cancer cell cultures and animal models. Overall, the evidence compiled points that CD36 is a valid target for the development of new anti-cancer therapies.

Evolution of Anti-SARS-CoV-2 Therapeutic Antibodies.

Since the first COVID-19 reports back in December of 2019, this viral infection caused by SARS-CoV-2 has claimed millions of lives. To control the COVID-19 pandemic, the Food and Drug Administration (FDA) and/or European Agency of Medicines (EMA) have granted Emergency Use Authorization (EUA) to nine therapeutic antibodies. Nonetheless, the natural evolution of SARS-CoV-2 has generated numerous variants of concern (VOCs) that have challenged the efficacy of the EUA antibodies. Here, we review the most relevant characteristics of these therapeutic antibodies, including timeline of approval, neutralization profile against the VOCs, selection methods of their variable regions, somatic mutations, HCDR3 and LCDR3 features, isotype, Fc modifications used in the therapeutic format, and epitope recognized on the receptor-binding domain (RBD) of SARS-CoV-2. One of the conclusions of the review is that the EUA therapeutic antibodies that still retain efficacy against new VOCs bind an epitope formed by conserved residues that seem to be evolutionarily conserved as thus, critical for the RBD:hACE-2 interaction. The information reviewed here should help to design new and more efficacious antibodies to prevent and/or treat COVID-19, as well as other infectious diseases.

TLR2 Regulates Mast Cell IL-6 and IL-13 Production During Listeria monocytogenes Infection.

Listeria monocytogenes (L.m) is efficiently controlled by several cells of the innate immunity, including the Mast Cell (MC). MC is activated by L.m inducing its degranulation, cytokine production and microbicidal mechanisms. TLR2 is required for the optimal control of L.m infection by different cells of the immune system. However, little is known about the MC receptors involved in recognizing this bacterium and whether these interactions mediate MC activation. In this study, we analyzed whether TLR2 is involved in mediating different MC activation responses during L.m infection. We found that despite MC were infected with L.m, they were able to clear the bacterial load. In addition, MC degranulated and produced ROS, TNF-α, IL-1ß, IL-6, IL-13 and MCP-1 in response to bacterial infection. Interestingly, L.m induced the activation of signaling proteins: ERK, p38 and NF-κB. When TLR2 was blocked, L.m endocytosis, bactericidal activity, ROS production and mast cell degranulation were not affected. Interestingly, only IL-6 and IL-13 production were affected when TLR2 was inhibited in response to L.m infection. Furthermore, p38 activation depended on TLR2, but not ERK or NF-κB activation. These results indicate that TLR2 mediates only some MC activation pathways during L.m infection, mainly those related to IL-6 and IL-13 production.

LPA1 Receptor Promotes Progesterone Receptor Phosphorylation through PKCα in Human Glioblastoma Cells.

Lysophosphatidic acid (LPA) induces a wide range of cellular processes and its signaling is increased in several cancers including glioblastoma (GBM), a high-grade astrocytoma, which is the most common malignant brain tumor. LPA1 receptor is expressed in GBM cells and its signaling pathways activate protein kinases C (PKCs). A downstream target of PKC, involved in GBM progression, is the intracellular progesterone receptor (PR), which can be phosphorylated by this enzyme, increasing its transcriptional activity. Interestingly, in GBM cells, PKCα isotype translocates to the nucleus after LPA stimulation, resulting in an increase in PR phosphorylation. In this study, we determined that LPA1 receptor activation induces protein-protein interaction between PKCα and PR in human GBM cells; this interaction increased PR phosphorylation in serine400. Moreover, LPA treatment augmented VEGF transcription, a known PR target. This effect was blocked by the PR selective modulator RU486; also, the activation of LPA1/PR signaling promoted migration of GBM cells. Interestingly, using TCGA data base, we found that mRNA expression of LPAR1 increases according to tumor malignancy and correlates with a lower survival in grade III astrocytomas. These results suggest that LPA1/PR pathway regulates GBM progression.

Quality attributes of partially hydrolyzed collagen in a liquid formulation used for skin care.

BACKGROUND: The deterioration of the skin accentuates over time, affecting its aesthetic appearance. This is characterized by the weakening of the mechanisms involved in the regeneration and repair of the dermal matrix. Consequently, the skin losses elasticity and smoothness resulting in the formation of wrinkles. The alternatives for facial rejuvenation include surgery, injection of botulinum toxin, and the application of masks. Topic products are less invasive, can be self-applied, and have an increased benefit/risk relationship. AIM: We developed a liquid formulation containing collagen hydrolyzed and evaluated the product by cutting-edge technology in order to define proper its quality attributes. METHODS: We employed nuclear magnetic resonance (NMR), size-exclusion chromatography (SEC), and mass spectrometry (MS). Additionally, we analyzed its cosmetical effect in five volunteers and we demonstrate the product safety. RESULTS: Our results demonstrate the following: (a) a stable secondary structure identity associated to the known triple helix arrangement in liquid and solid states; (b) a typical conformational flexibility depending on its hydration state; (c) thermal stability confirmed by liquid- and solid-state nuclear magnetic resonance schemes; and (d) a molecular mass distribution of peptides between 0.5 and 19.5 kDa. The product faded wrinkles in the forehead, an effect that remained after removing the mask. The formula was non-irritating and hypoallergenic. CONCLUSION: We characterized, using state-of-the-art methodologies, the quality attributes that are critical for the safety and beneficial effect of a new collagen-containing formula.

Antibody-drug conjugates: the new generation of biotechnological therapies against cancer.

Therapeutic antibodies are recombinant proteins used in the treatment of cancer. There is a new generation of monoclonal antibodies with activity against cancer cells, known as antibody-drug conjugates. These molecules are made up of three elements: a monoclonal antibody, a highly potent cytotoxic drug, and a chemical linker that binds them together. The antibody recognizes tumor antigens, thereby allowing targeted delivery of the cytotoxic agent to cancer cells. After recognizing its antigen, the antibody-drug conjugate is endocytosed by the target cells, where the protein fraction is degraded into lysosomes, releasing the cytotoxic drug. This article reviews antibody-drug conjugates general characteristics and describes the clinical evidence of efficacy and safety of the first four approved by regulatory agencies in the United States and Europe.

Los anticuerpos terapéuticos son proteínas recombinantes empleadas en el tratamiento del cáncer. Existe una nueva ­generación de anticuerpos monoclonales con actividad contra las células cancerosas, conocidos como anticuerpos conjugados a fármacos. Estas moléculas están integradas por tres elementos: un anticuerpo monoclonal, un fármaco citotóxico con alta potencia y un enlazador químico que los une. El anticuerpo reconoce antígenos tumorales, por lo que permite la entrega dirigida del agente citotóxico hacia las células cancerosas. Tras el reconocimiento de su antígeno, el anticuerpo conjugado a fármaco es endocitado por las células blanco, donde se induce la degradación lisosomal de la fracción proteica y se libera el fármaco citotóxico. En el presente artículo se revisan las características generales de los anticuerpos conjugados a fármacos y se describe la evidencia clínica de la eficacia y seguridad de los primeros cuatro aprobados por las agencias reguladoras de Estados Unidos y Europa.

Pranlukast Antagonizes CD49f and Reduces Stemness in Triple-Negative Breast Cancer Cells.

INTRODUCTION: Cancer stem cells (CSCs) drive the initiation, maintenance, and therapy response of breast tumors. CD49f is expressed in breast CSCs and functions in the maintenance of stemness. Thus, blockade of CD49f is a potential therapeutic approach for targeting breast CSCs. In the present study, we aimed to repurpose drugs as CD49f antagonists. MATERIALS AND METHODS: We performed consensus molecular docking using a subdomain of CD49f that is critical for heterodimerization and a collection of pharmochemicals clinically tested. Molecular dynamics simulations were employed to further characterize drug-target binding. Using MDA-MB-231 cells, we evaluated the effects of potential CD49f antagonists on 1) cell adhesion to laminin; 2) mammosphere formation; and 3) cell viability. We analyzed the effects of the drug with better CSC-selectivity on the activation of CD49f-downstream signaling by Western blot (WB) and co-immunoprecipitation. Expressions of the stem cell markers CD44 and SOX2 were analyzed by flow cytometry and WB, respectively. Transactivation of SOX2 promoter was evaluated by luciferase reporter assays. Changes in the number of CSCs were assessed by limiting-dilution xenotransplantation. RESULTS: Pranlukast, a drug used to treat asthma, bound to CD49f in silico and inhibited the adhesion of CD49f+ MDA-MB-231 cells to laminin, indicating that it antagonizes CD49f-containing integrins. Molecular dynamics analysis showed that pranlukast binding induces conformational changes in CD49f that affect its interaction with ß1-integrin subunit and constrained the conformational dynamics of the heterodimer. Pranlukast decreased the clonogenicity of breast cancer cells on mammosphere formation assay but had no impact on the viability of bulk tumor cells. Brief exposure of MDA-MB-231 cells to pranlukast altered CD49f-dependent signaling, reducing focal adhesion kinase (FAK) and phosphatidylinositol 3-kinase (PI3K) activation. Further, pranlukast-treated cells showed decreased CD44 and SOX2 expression, SOX2 promoter transactivation, and in vivo tumorigenicity, supporting that this drug reduces the frequency of CSC. CONCLUSION: Our results support the function of pranlukast as a CD49f antagonist that reduces the CSC population in triple-negative breast cancer cells. The pharmacokinetics and toxicology of this drug have already been established, rendering a potential adjuvant therapy for breast cancer patients.

Anticuerpos conjugados a fármaco: la nueva generación de terapias biotecnológicas contra el cáncer / Antibody-drug conjugates: the new generation of biotechnological therapies against cancer

Resumen Los anticuerpos terapéuticos son proteínas recombinantes empleadas en el tratamiento del cáncer. Existe una nueva generación de anticuerpos monoclonales con actividad contra las células cancerosas, conocidos como anticuerpos conjugados a fármacos. Estas moléculas están integradas por tres elementos: un anticuerpo monoclonal, un fármaco citotóxico con alta potencia y un enlazador químico que los une. El anticuerpo reconoce antígenos tumorales, por lo que permite la entrega dirigida del agente citotóxico hacia las células cancerosas. Tras el reconocimiento de su antígeno, el anticuerpo conjugado a fármaco es endocitado por las células blanco, donde se induce la degradación lisosomal de la fracción proteica y se libera el fármaco citotóxico. En el presente artículo se revisan las características generales de los anticuerpos conjugados a fármacos y se describe la evidencia clínica de la eficacia y seguridad de los primeros cuatro aprobados por las agencias reguladoras de Estados Unidos y Europa.

Abstract Therapeutic antibodies are recombinant proteins used in the treatment of cancer. There is a new generation of monoclonal antibodies with activity against cancer cells, known as antibody-drug conjugates. These molecules are made up of three elements: a monoclonal antibody, a highly potent cytotoxic drug, and a chemical linker that binds them together. The antibody recognizes tumor antigens, thereby allowing targeted delivery of the cytotoxic agent to cancer cells. After recognizing its antigen, the antibody-drug conjugate is endocytosed by the target cells, where the protein fraction is degradated into lysosomes, releasing the cytotoxic drug. This article reviews antibody-drug conjugates general characteristics and describes the clinical evidence of efficacy and safety of the first four approved by regulatory agencies in the United States and Europe.

Heptapeptide HP3 acts as a potent inhibitor of experimental imiquimod­induced murine psoriasis and impedes the trans­endothelial migration of mononuclear cells.

During the progression of psoriatic lesions, abundant cellular infiltration of myeloid cells, such as macrophages and activated dendritic cells, occurs in the skin and the infiltrating cells interact with naive lymphoid cells to generate a T helper (Th)1 and Th17 environment. Therapies to treat psoriasis include phototherapy, non­steroidal and steroidal drugs, as well as antibodies to block tumor necrosis factor­α, interleukin (IL)­17­A and IL­12/IL­23, which all focus on decreasing the proinflammatory hallmark of psoriasis. The present study obtained the heptapeptide HP3 derived from phage display technology that blocks mononuclear cell adhesion to endothelial cells and inhibits trans­endothelial migration in vitro. The activity of the heptapeptide in a murine model of psoriasis was also assessed, which indicated that early administration inhibited the development of psoriatic lesions. Therefore, the results suggested that HP3 may serve as a potential therapeutic target for psoriasis.

CD80 Expression Correlates with IL-6 Production in THP-1-Like Macrophages Costimulated with LPS and Dialyzable Leukocyte Extract (Transferon®).

Transferon® is a complex drug based on a mixture of low molecular weight peptides. This biotherapeutic is employed as a coadjuvant in clinical trials of several diseases, including viral infections and allergies. Given that macrophages play key roles in pathogen recognition, phagocytosis, processing, and antigen presentation, we evaluated the effect of Transferon® on phenotype and function of macrophage-like cells derived from THP-1 monocytes. We determined the surface expression of CD80 and CD86 by flow cytometry and IL-1ß, TNF-α, and IL-6 levels by ELISA. Transferon® alone did not alter the steady state of PMA-differentiated macrophage-like THP-1 cells. On the contrary, simultaneous stimulation of cells with Transferon® and LPS elicited a significant increase in CD80 (P ≤ 0.001) and CD86 (P ≤ 0.001) expression, as well as in IL-6 production (P ≤ 0.05) compared to the LPS control. CD80 expression and IL-6 production exhibited a positive correlation (r = 0.6, P ≤ 0.05) in cells exposed to Transferon® and LPS. Our results suggest that the administration of Transferon® induces the expression of costimulatory molecules and the secretion of cytokines in LPS-activated macrophages. Further studies are necessary to determine the implication of these findings in the therapeutic properties of Transferon®.

Transcriptome-based identification of lovastatin as a breast cancer stem cell-targeting drug.

BACKGROUND: Breast cancer is a neoplastic disease with high morbidity and mortality in women worldwide. Breast cancer stem cells (CSCs) have a significant function in tumor growth, recurrence, and therapeutic resistance. Thus, CSCs have been pointed as targets of new therapies for breast cancer. Herein, we aimed to repurpose certain drugs as breast CSC-targeting agents. METHODS: We compared a consensus breast CSC signature with the transcriptomic changes that were induced by over 1300 bioactive compounds using Connectivity Map. The effects of the selected drugs on SOX2 promoter transactivation, SOX2 expression, viability, clonogenicity, and ALDH activity in breast cancer cells were analyzed by luciferase assay, western blot, MTT assay, mammosphere formation assay, and ALDEFLUOR® test, respectively. Gene Set Enrichment Analysis (GSEA) was performed using the gene expression data from mammary tumors of mice that were treated with lovastatin. RESULTS: Five drugs (fasudil, pivmecillinam, ursolic acid, 16,16-dimethylprostaglandin E2, and lovastatin) induced signatures that correlated negatively with the query CSC signature. In vitro, lovastatin inhibited SOX2 promoter transactivation, and reduced the efficiency of mammosphere formation and the percentage of ALDH+ cells. Mevalonate mitigated the effects of lovastatin, suggesting that the targeting of CSCs by lovastatin was mediated by the inhibition of its reported target, 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR). By GSEA, lovastatin downregulated genes that are involved in stemness and invasiveness in mammary tumors, corroborating our in vitro findings. CONCLUSION: Lovastatin is a breast CSC-targeting drug. The inhibition of HMGCR might develop new adjuvant therapeutic strategies for breast tumors.

Determination of Peptide Profile Consistency and Safety of Collagen Hydrolysates as Quality Attributes.

Collagen hydrolysates are dietary supplements used for nutritional and medical purposes. They are complex mixtures of low-molecular-weight peptides obtained from the enzymatic hydrolysis of collagen, which provide intrinsic batch-to-batch heterogeneity. In consequence, the quality of these products, which is related to the reproducibility of their mass distribution pattern, should be addressed. Here, we propose an analytical approach to determine the peptide pattern as a quality attribute of Colagenart®, a product containing collagen hydrolysate. In addition, we evaluated the safety by measuring the viability of two cell lines exposed to the product. The consistency of peptide distribution was determined using Size Exclusion Chromatography (SEC), Mass Spectrometry coupled to a reversed phase UPLC system (MS-RP-UPLC), and Shaped-pulse off-resonance water-presaturation proton nuclear magnetic resonance spectrometry [1 Hwater_presat NMR]. The mass distribution pattern determined by SEC was in a range from 1.35 to 17 kDa, and from 2 to 14 kDa by MS-RP-UPLC. [1 Hwater_presat NMR] showed the detailed spin-systems of the collagen hydrolysates components by global assignment of backbone Hα and NH, as well as side-chain proton resonances. Additionally, short-range intraresidue connectivity pathways of identified spin-regions were obtained by a 2D homonuclear shift correlation Shaped-pulse solvent suppression COSY scheme. Safety analysis of Colagenart® was evaluated in CaCo-2 and HepG2 cells at 2.5 and 25 µg/mL and no negative effects were observed. The results demonstrated batch-to-batch reproducibility, which evinces the utility of this approach to establish the consistency of the quality attributes of collagen hydrolysates. PRACTICAL APPLICATION: We propose state-of-the art analytical methodologies (SEC, MS, and NMR) to evaluate peptide profile and composition of collagen hydrolysates as quality attributes. These methodologies are suitable to be implemented for quality control purposes.

Valproic acid promotes a decrease in mycobacterial survival by enhancing nitric oxide production in macrophages stimulated with IFN-γ.

Tuberculosis is one of the leading causes of mortality worldwide, it is caused by Mycobacterium tuberculosis (Mtb), a bacteria that employs several strategies to evade the host immune response. For instance, Mtb interferes with the overexpression of class II transactivator (CIITA) in macrophages exposed to IFN-γ by inhibiting histone acetylation at its promoter, which can be reverted by the histone deacetylase inhibitor (HDACi) sodium butyrate. In this work, we evaluated whether a different HDACi, valproic acid (VPA), could revert the inhibition of gene expression induced by Mtb. J774 macrophages treated with VPA and IFN-γ unexpectedly induced a higher expression of the inducible nitric oxide synthase and a higher production of nitric oxide when exposed to the 19 kDa lipoprotein of Mtb or the whole bacteria. However, VPA was unable to revert the inhibition of CIITA expression induced by the 19 kDa lipoprotein of Mtb. Finally, macrophages infected with Mtb and treated with VPA and IFN-γ showed a significant reduction in intracellular bacteria. Our findings suggest a new therapeutic potential of VPA for the treatment of tuberculosis.

ALTHEA Gold Libraries™: antibody libraries for therapeutic antibody discovery.

We describe here the design, construction and validation of ALTHEA Gold Libraries™. These single-chain variable fragment (scFv), semisynthetic libraries are built on synthetic human well-known IGHV and IGKV germline genes combined with natural human complementarity-determining region (CDR)-H3/JH (H3J) fragments. One IGHV gene provided a universal VH scaffold and was paired with two IGKV scaffolds to furnish different topographies for binding distinct epitopes. The scaffolds were diversified at positions identified as in contact with antigens in the known antigen-antibody complex structures. The diversification regime consisted of high-usage amino acids found at those positions in human antibody sequences. Functionality, stability and diversity of the libraries were improved throughout a three-step construction process. In a first step, fully synthetic primary libraries were generated by combining the diversified scaffolds with a set of synthetic neutral H3J germline gene fragments. The second step consisted of selecting the primary libraries for enhanced thermostability based on the natural capacity of Protein A to bind the universal VH scaffold. In the third and final step, the resultant stable synthetic antibody fragments were combined with natural H3J fragments obtained from peripheral blood mononuclear cells of a large pool of 200 donors. Validation of ALTHEA Gold Libraries™ with seven targets yielded specific antibodies in all the cases. Further characterization of the isolated antibodies indicated KD values as human IgG1 molecules in the single-digit and sub-nM range. The thermal stability (Tm) of all the antigen-binding fragments was 75°C-80°C, demonstrating that ALTHEA Gold Libraries™ are a valuable source of specific, high affinity and highly stable antibodies.

Targeting Breast Cancer Stem Cells: A Methodological Perspective.

Cancer Stem Cells (CSCs) constitute a subpopulation at the top of the tumor cell hierarchy that contributes to tumor heterogeneity and is uniquely capable of seeding new tumors. Because of their biological properties, CSCs have been pointed out as therapeutic targets for the development of new therapies against breast cancer. The identification of drugs that selectively target breast CSCs requires a clear understanding of their biological functions and the experimental methods to evaluate such hallmarks. Herein, we review the methods to study breast CSCs properties and discuss their value in the preclinical evaluation of CSC-targeting drugs.

The dialyzable leukocyte extract TransferonTM inhibits tumor growth and brain metastasis in a murine model of prostate cancer.

Prostate cancer (PCa) is the second most frequently diagnosed cancer in men worldwide. Dialyzed Leukocyte Extracts (DLEs) are heterogeneous mixtures of low-molecular-weight peptides that improve clinical responses in various diseases. Here, we analyzed the effects of TransferonTM, a commercial DLE with characterized active pharmaceutical ingredient and proven batch-to-batch reproducibility, in preclinical models of PCa. We employed v-Src-transformed murine prostate epithelial (PEC-Src) cells, which recapitulate the transcriptional profiles in human PCa, can be grown in immunocompetent mice, and consistently form bone and brain metastases. In vitro, TransferonTM did not induce cytotoxicity nor alterations in migration /invasion of PEC-Src cells. In vivo, TransferonTM reduced metastatic dissemination after intracardiac injection of PEC-Src and inhibited tumor growth of subcutaneous isotransplants. The antineoplastic effect of TransferonTM correlated with changes in tumor infiltration, increased serum concentrations of IL-12 and CXCL1, and reduced levels of VEGF. Our results suggest that the antineoplastic effect produced by TransferonTM is due to its immunomodulatory activity and not by a direct effect on cancer cells, and indicate that TransferonTM could be beneficial as adjuvant therapy in PCa patients.

In Vitro Methods for Comparing Target Binding and CDC Induction Between Therapeutic Antibodies: Applications in Biosimilarity Analysis.

Therapeutic monoclonal antibodies (mAbs) are relevant to the treatment of different pathologies, including cancers. The development of biosimilar mAbs by pharmaceutical companies is a market opportunity, but it is also a strategy to increase drug accessibility and reduce therapy-associated costs. The protocols detailed here describe the evaluation of target binding and CDC induction by rituximab in Daudi cells. These two functions require different structural regions of the antibody and are relevant to the clinical effect induced by rituximab. The protocols allow the side-to-side comparison of a reference rituximab and a marketed rituximab biosimilar. The evaluated products showed differences both in target binding and CDC induction, suggesting that there are underlying physicochemical differences and highlighting the need to analyze the impact of those differences in the clinical setting. The methods reported here constitute simple and inexpensive in vitro models for the evaluation of the activity of rituximab biosimilars. Thus, they can be useful during biosimilar development, as well as for quality control in biosimilar production. Furthermore, the presented methods can be extrapolated to other therapeutic mAbs.

Virtual screening-driven repositioning of etoposide as CD44 antagonist in breast cancer cells.

CD44 is a receptor for hyaluronan (HA) that promotes epithelial-to-mesenchymal transition (EMT), induces cancer stem cell (CSC) expansion, and favors metastasis. Thus, CD44 is a target for the development of antineoplastic agents. In order to repurpose drugs as CD44 antagonists, we performed consensus-docking studies using the HA-binding domain of CD44 and 11,421 molecules. Drugs that performed best in docking were examined in molecular dynamics simulations, identifying etoposide as a potential CD44 antagonist. Ligand competition and cell adhesion assays in MDA-MB-231 cells demonstrated that etoposide decreased cell binding to HA as effectively as a blocking antibody. Etoposide-treated MDA-MB-231 cells developed an epithelial morphology; increased their expression of E-cadherin; and reduced their levels of EMT-associated genes and cell migration. By gene expression analysis, etoposide reverted an EMT signature similarly to CD44 knockdown, whereas other topoisomerase II (TOP2) inhibitors did not. Moreover, etoposide decreased the proportion of CD44+/CD24- cells, lowered chemoresistance, and blocked mammosphere formation. Our data indicate that etoposide blocks CD44 activation, impairing key cellular functions that drive malignancy, thus rendering it a candidate for further translational studies and a potential lead compound in the development of new CD44 antagonists.