Browsing by Author "Metz, Claudia"
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- ItemD-Propranolol Impairs EGFR Trafficking and Destabilizes Mutant p53 Counteracting AKT Signaling and Tumor Malignancy(2021) Barra, Jonathan; Cerda-Infante, Javier; Sandoval, Lisette; Gajardo-Meneses, Patricia; Henriquez, Jenny F.; Labarca, Mariana; Metz, Claudia; Venegas, Jaime; Retamal, Claudio; Oyanadel, Claudia; Cancino, Jorge; Soza, Andrea; Cuello, Mauricio A.; Carlos Roa, Juan; Montecinos, Viviana P.; Gonzalez, AlfonsoSimple Summary Cancer progression is frequently driven by altered functions of EGFR belonging to the tyrosine-kinase family of growth factor receptors and by the transcription factor p53, which is called the "genome guardian". We report that D-Propranolol, previously used for other purposes in human patients, has antitumor effects involving a redistribution of cell surface EGFR to intracellular compartments and degradation of gain-of-function mutants of p53 (GOF-mutp53). These effects can be seen in cancer cell lines expressing EGFR and GOF-mutp53 and are reproduced in vivo, reducing tumor growth and prolonging survival of xenografted mice. D-Propranolol is proposed as a prototype drug for a new strategy against highly aggressive EGFR- and mutp53-expressing tumors. Cancer therapy may be improved by the simultaneous interference of two or more oncogenic pathways contributing to tumor progression and aggressiveness, such as EGFR and p53. Tumor cells expressing gain-of-function (GOF) mutants of p53 (mutp53) are usually resistant to EGFR inhibitors and display invasive migration and AKT-mediated survival associated with enhanced EGFR recycling. D-Propranolol (D-Prop), the non-beta blocker enantiomer of propranolol, was previously shown to induce EGFR internalization through a PKA inhibitory pathway that blocks the recycling of the receptor. Here, we first show that D-Prop decreases the levels of EGFR at the surface of GOF mutp53 cells, relocating the receptor towards recycling endosomes, both in the absence of ligand and during stimulation with high concentrations of EGF or TGF-alpha. D-Prop also inactivates AKT signaling and reduces the invasive migration and viability of these mutp53 cells. Unexpectedly, mutp53 protein, which is stabilized by interaction with the chaperone HSP90 and mediates cell oncogenic addiction, becomes destabilized after D-Prop treatment. HSP90 phosphorylation by PKA and its interaction with mutp53 are decreased by D-Prop, releasing mutp53 towards proteasomal degradation. Furthermore, a single daily dose of D-Prop reproduces most of these effects in xenografts of aggressive gallbladder cancerous G-415 cells expressing GOF R282W mutp53, resulting in reduced tumor growth and extended mice survival. D-Prop then emerges as an old drug endowed with a novel therapeutic potential against EGFR- and mutp53-driven tumor traits that are common to a large variety of cancers.
- ItemEndogenous Galectin-8 protects against Th17 infiltration and fibrosis following acute kidney injury(Springer Nature, 2025) Perez-Moreno, Elisa; Peña, Adely de la; Toledo, Tomás; Saez, Javiera; Pérez-Molina, Francisca; Espinoza, Sofía; Metz, Claudia; Díaz-Valdivia, Nicole; Azócar, Lorena; Prado, Carolina; Pacheco, Rodrigo; Segovia-Miranda, Fabian; Godoy, Alejandro S.; Amador, Cristian A.; Feuerhake González, Teo; González, Alfonso; Soza, AndreaBackground Acute kidney injury (AKI) is a serious clinical condition characterized by a rapid decline in renal function, often progressing to chronic kidney disease (CKD) and fibrosis. The endogenous mechanisms influencing kidney injury resolution or maladaptive repair remain poorly understood. Galectin‑8 (Gal‑8), a tandem‑repeat β‑galactosidebinding lectin, plays a role in epithelial cell proliferation, epithelial‑mesenchymal transition, and immune regulation, all of which are critical in AKI outcomes. While exogenous Gal‑8 administration has shown renoprotective effects, its endogenous role in kidney injury progression and resolution remains unclear. Methods To investigate the endogenous role of Gal‑8 in AKI, we compared the responses of Gal‑8 knockout (Gal8‑KO; Lgals8−/− bearing a β‑gal cassette under the Lgals8 gene promoter) and wild‑type (Lgals8+/+) mice in a nephrotoxic folic acid (FA)‑induced AKI model. Renal Gal‑8 expression was assessed by β‑galactosidase staining, lectin‑marker colocalization, and RT‑qPCR. Renal function, structure, and immune responses were evaluated at the acute (day 2) and fibrotic (day 14) phases of injury. Plasma creatinine levels were measured to assess renal function, while histological analyses evaluated tubular damage, renal inflammation, and extracellular matrix deposition. Flow cytometry was performed to characterize the immune response, focusing on pro‑inflammatory T cells. Results Galectin‑8 was predominantly expressed in the renal cortex, localizing to tubules, glomeruli, and blood vessels, with its levels decreasing by half following AKI. Both Lgals8+/+ and Lgals8−/− mice exhibited similar renal function and structure impairments during the acute phase, though Lgals8+/+ mice showed slightly worse damage. By the fibrotic phase, Lgals8−/− mice exhibited more pronounced cortical damage and fibrosis, characterized by increased type I and III collagen deposition and enhanced Th17 cell infiltration, while myofibroblast activation remained comparable to that of Lgals8+/+ mice. Conclusions Endogenous Gal‑8 does not significantly protect the kidney during the acute phase and is dispensable for cell proliferation and death in response to AKI. However, it is crucial in preventing maladaptive repair by regulating.
- ItemGalectin-8 Induces Apoptosis in Jurkat T Cells by Phosphatidic Acid-mediated ERK1/2 Activation Supported by Protein Kinase A Down-regulation(AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 2009) Norambuena, Andres; Metz, Claudia; Vicuna, Lucas; Silva, Antonia; Pardo, Evelyn; Oyanadel, Claudia; Massardo, Loreto; Gonzalez, Alfonso; Soza, AndreaGalectins have been implicated in T cell homeostasis playing complementary pro-apoptotic roles. Here we show that galectin-8 (Gal-8) is a potent pro-apoptotic agent in Jurkat T cells inducing a complex phospholipase D/phosphatidic acid signaling pathway that has not been reported for any galectin before. Gal-8 increases phosphatidic signaling, which enhances the activity of both ERK1/2 and type 4 phosphodiesterases (PDE4), with a subsequent decrease in basal protein kinase A activity. Strikingly, rolipram inhibition of PDE4 decreases ERK1/2 activity. Thus Gal-8-induced PDE4 activation releases a negative influence of cAMP/protein kinase A on ERK1/2. The resulting strong ERK1/2 activation leads to expression of the death factor Fas ligand and caspase-mediated apoptosis. Several conditions that decrease ERK1/2 activity also decrease apoptosis, such as anti-Fas ligand blocking antibodies. In addition, experiments with freshly isolated human peripheral blood mononuclear cells, previously stimulated with anti-CD3 and anti-CD28, show that Gal-8 is pro-apoptotic on activated T cells, most likely on a subpopulation of them. Anti-Gal-8 autoantibodies from patients with systemic lupus erythematosus block the apoptotic effect of Gal-8. These results implicate Gal-8 as a novel T cell suppressive factor, which can be counterbalanced by function-blocking autoantibodies in autoimmunity.
- ItemGalectin-8 induces partial epithelial-mesenchymal transition with invasive tumorigenic capabilities involving a FAK/EGFR/proteasome pathway in Madin-Darby canine kidney cells(2018) Oyanadel, Claudia; Holmes, Christopher; Pardo, Evelyn; Retamal, Claudio; Shaughnessy, Ronan; Smith, Patricio; Cortes, Priscilla; Bravo-Zehnder, Marcela; Metz, Claudia; Feuerhake, Teo; Romero, Diego, V; Carlos Roa, Juan; Montecinos, Viviana; Soza, Andrea; Gonzalez, AlfonsoEpithelial cells can acquire invasive and tumorigenic capabilities through epithelial-mesenchymal- transition (EMT). The glycan-binding protein galectin-8 (Gal-8) activates selective beta 1-integrins involved in EMT and is overexpressed by certain carcinomas. Here we show that Gal-8 overexpression or exogenous addition promotes proliferation, migration, and invasion in nontumoral Madin-Darby canine kidney (MDCK) cells, involving focal-adhesion kinase (FAK)-mediated transactivation of the epidermal growth factor receptor (EGFR), likely triggered by alpha 5 beta 1 integrin binding. Under subconfluent conditions, Gal-8-overexpressing MDCK cells (MDCK-Gal-8(H)) display hallmarks of EMT, including decreased E-cadherin and up-regulated expression of vimentin, fibronectin, and Snail, as well as increased beta-catenin activity. Changes related to migration/invasion included higher expression of alpha 5 beta 1 integrin, extracellular matrix-degrading MMP13 and urokinase plasminogen activator/urokinase plasminogen activator receptor (uPA/uPAR) protease systems. Gal-8-stimulated FAK/EGFR pathway leads to proteasome overactivity characteristic of cancer cells. Yet MDCK-Gal-8H cells still develop apical/basolateral polarity reverting EMT markers and proteasome activity under confluence. This is due to the opposite segregation of Gal-8 secretion (apical) and beta 1-integrins distribution (basolateral). Strikingly, MDCK-Gal-8(H) cells acquired tumorigenic potential, as reflected in anchorage-independent growth in soft agar and tumor generation in immunodeficient NSG mice. Therefore, Gal-8 can promote oncogenic-like transformation of epithelial cells through partial and reversible EMT, accompanied by higher proliferation, migration/invasion, and tumorigenic properties.
- ItemPhosphatidic Acid Induces Ligand-independent Epidermal Growth Factor Receptor Endocytic Traffic through PDE4 Activation(AMER SOC CELL BIOLOGY, 2010) Norambuena, Andres; Metz, Claudia; Jung, Juan E.; Silva, Antonia; Otero, Carolina; Cancino, Jorge; Retamal, Claudio; Valenzuela, Juan C.; Soza, Andrea; Gonzalez, AlfonsoEndocytosis modulates EGFR function by compartmentalizing and attenuating or enhancing its ligand-induced signaling. Here we show that it can also control the cell surface versus intracellular distribution of empty/inactive EGFR. Our previous observation that PKA inhibitors induce EGFR internalization prompted us to test phosphatidic acid (PA) generated by phospholipase D (PLD) as an endogenous down-regulator of PKA activity, which activates rolipram-sensitive type 4 phosphodiesterases (PDE4) that degrade cAMP. We found that inhibition of PA hydrolysis by propranolol, in the absence of ligand, provokes internalization of inactive (neither tyrosine-phosphorylated nor ubiquitinated) EGFR, accompanied by a transient increase in PA levels and PDE4s activity. This EGFR internalization is mimicked by PA micelles and is strongly counteracted by PLD2 silencing, rolipram or forskolin treatment, and PKA overexpression. Accelerated EGFR endocytosis seems to be mediated by clathrin-dependent and -independent pathways, leading to receptor accumulation in juxtanuclear recycling endosomes, also due to a decreased recycling. Internalized EGFR can remain intracellular without degradation for several hours or return rapidly to the cell surface upon discontinuation of the stimulus. This novel regulatory mechanism of EGFR, also novel function of signaling PA, can transmodulate receptor accessibility in response to heterologous stimuli.
- ItemPhosphatidic acid-PKA signaling regulates p38 and ERK1/2 functions in ligand-independent EGFR endocytosis(2021) Metz, Claudia; Oyanadel, Claudia; Jung, Juan; Retamal, Claudio; Cancino, Jorge; Barra, Jonathan; Venegas, Jaime; Du, Guangwei; Soza, Andrea; Gonzalez, AlfonsoLigand-independent epidermal growth factor receptor (EGFR) endocytosis is inducible by a variety of stress conditions converging upon p38 kinase. A less known pathway involves phosphatidic acid (PA) signaling toward the activation of type 4 phosphodiesterases (PDE4) that decrease cAMP levels and protein kinase A (PKA) activity. This PA/PDE4/PKA pathway is triggered with propranolol used to inhibit PA hydrolysis and induces clathrin-dependent and clathrin-independent endocytosis, followed by reversible accumulation of EGFR in recycling endosomes. Here we give further evidence of this signaling pathway using biosensors of PA, cAMP, and PKA in live cells and then show that it activates p38 and ERK1/2 downstream the PKA inhibition. Clathrin-silencing and IN/SUR experiments involved the activity of p38 in the clathrin-dependent route, while ERK1/2 mediates clathrin-independent EGFR endocytosis. The PA/PDE4/PKA pathway selectively increases the EGFR endocytic rate without affecting LDLR and TfR constitute endocytosis. This selectiveness is probably because of EGFR phosphorylation, as detected in Th1046/1047 and Ser669 residues. The EGFR accumulates at perinuclear recycling endosomes colocalizing with TfR, fluorescent transferrin, and Rab11, while a small proportion distributes to Alix-endosomes. A non-selective recycling arrest includes LDLR and TfR in a reversible manner. The PA/PDE4/PKA pathway involving both p38 and ERK1/2 expands the possibilities of EGFR transmodulation and interference in cancer.