Papers by Gretchen Bergado
International Journal of Biological Macromolecules, 2022
Dipeptidyl peptidase IV (DPP-IV, EC 3.4.14.5) is an abundant serine aminopeptidase that preferent... more Dipeptidyl peptidase IV (DPP-IV, EC 3.4.14.5) is an abundant serine aminopeptidase that preferentially cleaves N-terminal Xaa-Pro or Xaa-Ala dipeptides from oligopeptides. Inhibitors of DPP-IV activity are used for treating type 2 diabetes mellitus and other diseases. DPP-IV is also involved in tumor progression. We identified four new non-peptide tight-binding competitive inhibitors of porcine DPP-IV by virtual screening and enzymatic assays. Molecular docking simulations supported the competitive behavior, and the selectivity of one of the compounds in the DPP-IV family. Since three of these inhibitors are also aminopeptidase N (APN) inhibitors, we tested their impact on APN+/DPP-IV+ and DPP-IV+ human tumor cells' viability. Using kinetic assays, we determined that HL-60 tumor cells express both APN and DPP-IV activities and that MDA-MB-231 tumor cells express DPP-IV activity. The inhibitors had a slight inhibitory effect on human HEK-293 cell viability but reduced the viability of APN+/DPP-IV+ and DPP-IV+ human tumor cells more potently. Remarkably, the intraperitoneal injection of these compounds inhibited DPP-IV activity in rat brain, liver, and pancreas. In silico studies suggested inhibitors binding to serum albumin contribute to blood-brain barrier crossing. The spectrum of action of some of these compounds may be useful for niche applications.
International Journal of Biological Macromolecules, Dec 1, 2020
Bestatin and bacitracin are inhibitors of metallo aminopeptidases and bacterial proteases. Howeve... more Bestatin and bacitracin are inhibitors of metallo aminopeptidases and bacterial proteases. However, their effects on other human peptidases, like dipeptidyl peptidase IV (DPP-IV, EC 3.4.14.5) are not established. Inhibitors of DPP-IV activity are used for treating type 2 diabetes mellitus, cancers and immune system diseases. Bacitracin and bestatin inhibited porcine membrane-bound DPP-IV (pDPP-IV) activity. Mechanisms were different, i.e. non-competitive with α > 1 (α = 3.9) and K i value of 75 μM for bestatin, and competitive with K i value of 630 μM for bacitracin. The binding mode in the tertiary complex enzyme:substrate:bestatin suggested the structural basis of the inhibitory effect and that bestatin is potentially selective for DPP-IV, ineffective vs. S9 family members dipeptidyl peptidase 8/9 and fibroblast activation protein. In the human melanoma MeWo cell line, bestatin and bacitracin inhibited aminopeptidase N (APN) and DPP-IV activities, reduced cell viability and increased DNA fragmentation, suggesting induction of apoptosis. Since bacitracin and bestatin are already marketed drugs, studying in depth the molecular mechanisms underlying their effects on melanoma cells is warranted. Additionally, bestatin emerges as a new lead compound for the development of DPP-IV inhibitors, and a promising dual APN/DPP-IV inhibitor for the treatment of pathologies in which both enzymes are upregulated.
Pure and Applied Chemistry, May 9, 2023
Bufadienolides are steroids that inhibit the Na+/K+ ATPase pump. Recent studies show that members... more Bufadienolides are steroids that inhibit the Na+/K+ ATPase pump. Recent studies show that members of the bufadienolide family also inhibit the activity of aminopeptidase N (APN). APN is upregulated in different pathologies, including cancer and is a current target for drug development. Bufadienolides are cytotoxic in tumor cells, but there is no enough evidences that inhibition of APN activity contributes to their effect. In the present contribution we investigated the effect of another member of the bufadienolide family, bufotalin, on porcine APN (pAPN) activity. Bufotalin inhibited pAPN activity with K i values in the submicromolar range and an uncompetitive inhibition mechanism; it also inhibited porcine aminopeptidase A (pAPA) activity, but with a classical reversible competitive inhibition mechanism. In addition, we determined the effect of bufotalin on the viability/metabolism of APN+ A549, H292, MeWo and CT26 cancer cells. Bufotalin was cytotoxic in a dose dependent manner; the highest cytotoxicity was detected in A549 cells, the cells with the highest APN activity. Thus, tumor cell line sensitivity to the cytotoxic effect of bufotalin correlates with cell surface APN activity.
Neurotoxicology, Dec 1, 2021
The number of people with dementia worldwide is estimated at 50 million by 2018 and continues to ... more The number of people with dementia worldwide is estimated at 50 million by 2018 and continues to rise mainly due to increasing aging and population growth. Clinical impact of current interventions remains modest and all efforts aimed at the identification of new therapeutic approaches are therefore critical. Previously, we showed that JM-20, a dihydropyridine-benzodiazepine hybrid molecule, protected memory processes against scopolamine-induced cholinergic dysfunction. In order to gain further insight into the therapeutic potential of JM-20 on cognitive decline and Alzheimer's disease (AD) pathology, here we evaluated its neuroprotective effects after chronic aluminum chloride (AlCl3) administration to rats and assessed possible alterations in several types of episodic memory and associated pathological mechanisms. Oral administration of aluminum to rodents recapitulates several neuropathological alterations and cognitive impairment, being considered a convenient tool for testing the efficacy of new therapies for dementia. We used behavioral tasks to test spatial, emotional- associative and novel object recognition memory, as well as molecular, enzymatic and histological assays to evaluate selected biochemical parameters. Our study revealed that JM-20 prevented memory decline alongside the inhibition of AlCl3 -induced oxidative stress, increased AChE activity, TNF-α and pro-apoptotic proteins (like Bax, caspase-3, and 8) levels. JM-20 also protected against neuronal damage in the hippocampus and prefrontal cortex. Our findings expanded our understanding of the ability of JM-20 to preserve memory in rats under neurotoxic conditions and confirm its potential capacity to counteract cognitive impairment and etiological factors of AD by breaking the progression of key steps associated with neurodegeneration.
Pure and Applied Chemistry
Bufadienolides are steroids that inhibit the Na+/K+ ATPase pump. Recent studies show that members... more Bufadienolides are steroids that inhibit the Na+/K+ ATPase pump. Recent studies show that members of the bufadienolide family also inhibit the activity of aminopeptidase N (APN). APN is upregulated in different pathologies, including cancer and is a current target for drug development. Bufadienolides are cytotoxic in tumor cells, but there is no enough evidences that inhibition of APN activity contributes to their effect. In the present contribution we investigated the effect of another member of the bufadienolide family, bufotalin, on porcine APN (pAPN) activity. Bufotalin inhibited pAPN activity with K i values in the submicromolar range and an uncompetitive inhibition mechanism; it also inhibited porcine aminopeptidase A (pAPA) activity, but with a classical reversible competitive inhibition mechanism. In addition, we determined the effect of bufotalin on the viability/metabolism of APN+ A549, H292, MeWo and CT26 cancer cells. Bufotalin was cytotoxic in a dose dependent manner; t...
Archives of Virology
There is an urgent need to understand severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2... more There is an urgent need to understand severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-host interactions involved in virus spread and pathogenesis, which might contribute to the identification of new therapeutic targets. In this study, we investigated the presence of SARS-CoV-2 in postmortem lung, kidney, and liver samples of patients who died with coronavirus disease (COVID-19) and its relationship with host factors involved in virus spread and pathogenesis, using microscopy-based methods. The cases analyzed showed advanced stages of diffuse acute alveolar damage and fibrosis. We identified the SARS-CoV-2 nucleocapsid (NC) in a variety of cells, colocalizing with mitochondrial proteins, lipid droplets (LDs), and key host proteins that have been implicated in inflammation, tissue repair, and the SARS-CoV-2 life cycle (vimentin, NLRP3, fibronectin, LC3B, DDX3X, and PPARγ), pointing to vimentin and LDs as platforms involved not only in the viral life cycle but also in infl...
International Journal of Infectious Diseases
Frontiers in Oncology
BackgroundAntitumor therapies targeting HER1/EGFR and HER2, such as monoclonal antibodies (MAbs) ... more BackgroundAntitumor therapies targeting HER1/EGFR and HER2, such as monoclonal antibodies (MAbs) and tyrosine-kinase inhibitors (TKIs), have demonstrated a significant clinical benefit, but the emergence of resistance limits long-term efficacy. While secondary HER1 mutations confer tolerance to TKI, compensatory upregulation of HER2 drives resistance to anti-HER1 MAbs, which identifies MAb combinations targeting both receptors as an attractive therapeutic strategy. Nevertheless, toxicity hampers the clinical validation of this approach. Alternatively, cancer vaccines may induce antibodies directed against several antigens with less concern about induced toxicity.MethodsPolyclonal antibodies (PAbs) targeting HER1 and HER2 were induced in mice or rabbits through immunization. Recognition of different epitopes on targets by PAbs was validated by phage-display technology. Receptor downregulation was evaluated by flow cytometry, immunofluorescence, and Western blot. MTT assays assessed c...
Med
Phase IIb of SOBERANA 02 vaccine candidate demonstrated its safety and immunogenicity in a two-or... more Phase IIb of SOBERANA 02 vaccine candidate demonstrated its safety and immunogenicity in a two-or three-dose heterologous schedule with SOBERANA Plus in adults aged 19-80. Neutralizing antibodies against D614G were detected after 7-8 months. Neutralizing IgG antibodies were detected against D614G and VOCs Alpha, Beta, Delta, and Omicron.
Katia Garcia Duardo, Development Process Direction, Center of Molecular Immunology [email protected]... more Katia Garcia Duardo, Development Process Direction, Center of Molecular Immunology [email protected] Yanet Cueto Cabañas, Institute of Pharmacy and Food Sciences, Havana University Gretchen Bergado Baez, Tumoral Biology Direction, Center of Molecular Immunology Judith Raymond Pous, System Biology Direction, Center of Molecular Immunology Estela Yamilet Rabasa Legón, Development Process Direction, Center of Molecular Immunology Adolfo Castillo Vitlloch, Development Process Direction, Center of Molecular Immunology Kathya R. de la Luz Hernández, Development Process Direction, Center of Molecular Immunology
BackgroundSOBERANA 02 is a COVID-19 conjugate vaccine candidate based on SARS-CoV-2 recombinant R... more BackgroundSOBERANA 02 is a COVID-19 conjugate vaccine candidate based on SARS-CoV-2 recombinant RBD conjugated to tetanus toxoid. SOBERANA Plus antigen is dimeric-RBD. Here we report safety, reactogenicity and immunogenicity from phase I and IIa clinical trials using two-doses SOBERANA 02 (homologous protocol) and three-doses (homologous) or heterologous (with SOBERANA Plus) protocols.MethodWe performed an open-label, monocentric, sequential and adaptive phase I for evaluating safety, reactogenicity and exploring immunogenicity of SOBERANA 02 in two formulations (15 and 25 μg) in 40 subjects, 19–59 years old. Phase IIa was open-label including 100 volunteers 19–80 years, receiving two doses of SOBERANA 02-25 μg. In both trials, half of volunteers received a third dose of SOBERANA 02, half received a heterologous dose of SOBERANA Plus-50 μg. Primary outcomes were safety and reactogenicity. The secondary outcome was vaccine immunogenicity evaluated by anti-RBD IgG ELISA, molecular neu...
Immunopharmacology and Immunotoxicology, 2021
Cancers, 2020
Although two growth factor receptors, EGFR and HER2, are amongst the best targets for cancer trea... more Although two growth factor receptors, EGFR and HER2, are amongst the best targets for cancer treatment, no agents targeting HER3, their kinase-defective family member, have so far been approved. Because emergence of resistance of lung tumors to EGFR kinase inhibitors (EGFRi) associates with compensatory up-regulation of HER3 and several secreted forms, we anticipated that blocking HER3 would prevent resistance. As demonstrated herein, a neutralizing anti-HER3 antibody we generated can clear HER3 from the cell surface, as well as reduce HER3 cleavage by ADAM10, a surface metalloproteinase. When combined with a kinase inhibitor and an anti-EGFR antibody, the antibody completely blocked patient-derived xenograft models that acquired resistance to EGFRi. We found that the underlying mechanism involves posttranslational downregulation of HER3, suppression of MET and AXL upregulation, as well as concomitant inhibition of AKT signaling and upregulation of BIM, which mediates apoptosis. Thu...
Seminars in Oncology, 2018
The human epidermal growth factor receptor 1 (HER1) is a tumor associated antigen that has been v... more The human epidermal growth factor receptor 1 (HER1) is a tumor associated antigen that has been validated as a clinical target for several passive, non-immune therapies currently approved for the treatment epithelial tumors. HER1 is an oncogene that not only promotes tumor progression and survival, but also immune-escape. Its overexpression in some epithelial malignancies has been correlated with a poor prognosis. We developed an approach to target HER1 by specific active immunotherapy, recognizing the extracellular domain of the receptor, using a combination of VSSP and Montanide ISA 51 as adjuvants. We summarize the results obtained with this vaccine in both the preclinical and clinical settings, emphasizing the importance of the induction of both humoral and cellular responses for the success of cancer vaccines, as safe therapeutic alternatives for the treatment of cancer.
Revista Cubana de …, 2009
Oncotarget, 2017
The human epidermal growth factor receptor (HER1) and its partner HER2 are extensively described ... more The human epidermal growth factor receptor (HER1) and its partner HER2 are extensively described oncogenes and validated targets for cancer therapy. However, the effectiveness of monospecific therapies targeting these receptors is hampered by resistance emergence, which is frequently associated with the upregulation of other members of HER family. Combined therapies using monoclonal antibodies or tyrosine kinase inhibitors have been suggested as a promising strategy to circumvent this resistance mechanism. We propose an alternative approach based on simultaneous inactivation of HER1 and HER2 by multi-epitope blockade with specific polyclonal antibodies induced by vaccination. Elicited antibodies impaired both receptors activation and induced their degradation, which caused the inhibition of down-signaling cascades. This effect was translated into cell cycle arrest and apoptosis induction of human tumor cells. Elicited antibodies were able to reduce the viability of a panel of human tumor lines with differential expression levels of HER1 and HER2. The most significant effects were obtained in the tumor lines with lower expression levels of both receptors. These new insights would contribute to the rational design of HER receptors targeting multivalent vaccines, as an encouraging approach for the treatment of cancer patients.
International Journal of Biological Macromolecules
ACS Chemical Biology, 2021
Controlling the global COVID-19 pandemic depends, among other measures, on developing preventive ... more Controlling the global COVID-19 pandemic depends, among other measures, on developing preventive vaccines at an unprecedented pace. Vaccines approved for use and those in development intend to use neutralizing antibodies to block viral sites binding to the host's cellular receptors. Virus infection is mediated by the spike glycoprotein trimer on the virion surface via its receptor binding domain (RBD). Antibody response to this domain is an important outcome of the immunization and correlates well with viral neutralization. Here we show that macromolecular constructs with recombinant RBD conjugated to tetanus toxoid induce a potent immune response in laboratory animals. Some advantages of the immunization with the viral antigen coupled to tetanus toxoid have become evident such as predominant IgG immune response due to affinity maturation and long-term specific B-memory cells. This paper demonstrates that subunit conjugate vaccines can be an alternative for COVID-19, paving the way for other viral conjugate vaccines based on the use of small viral proteins involved in the infection process.
Archives of Cancer Science and Therapy
Immunization with human recombinant EGF chemically bound to the P64k protein of Neisseria meningi... more Immunization with human recombinant EGF chemically bound to the P64k protein of Neisseria meningitides (hrEGF-P64k) and adjuvanted in Montanide ISA 51 VG (Montanide) is an efficient strategy to induce polyclonal antibodies (PAbs) response targeting this self -antigen in cancer patients, which is the basis of the CIMAvax-EGF vaccine. The neutralizing potential of EGF-specific induced PAbs supports promising clinical data obtained to date with this vaccine. Herein, we evaluated a combination of very small-size proteoliposomes (VSSP) and aluminum hydroxide (Alum) as a novel adjuvant to induce specific PAbs with neutralizing and anti-proliferative properties on tumor cells, considering EGF as a model antigen. Toxicity at the injection site was not detected for the vaccine formulation containing VSSP/Alum, and it was immunogenic in BALB/c mice, as evidenced by the induction of high titers of EGF-specific polyclonal antibodies (PAbs). While schedule optimization increased the magnitude of...
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Papers by Gretchen Bergado