Browsing by Author "Quest, Andrew F. G."

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    AT2 Receptor Mediated Activation of the Tyrosine Phosphatase PTP1B Blocks Caveolin-1 Enhanced Migration, Invasion and Metastasis of Cancer Cells
    (2019) Martínez-Meza, Samuel; Díaz, Jorge; Sandoval-Bórquez, Alejandra; Valenzuela-Valderrama, Manuel; Díaz-Valdivia, Natalia; Rojas-Celis, Victoria; Contreras, Pamela; Huilcaman, Ricardo; Ocaranza Jeraldino, María Paz; Chiong, Mario; Leyton, Lissette; Lavandero, Sergio; Quest, Andrew F. G.
    The renin-angiotensin receptor AT2R controls systemic blood pressure and is also suggested to modulate metastasis of cancer cells. However, in the latter case, the mechanisms involved downstream of AT2R remain to be defined. We recently described a novel Caveolin-1(CAV1)/Ras-related protein 5A (Rab5)/Ras-related C3 botulinum toxin substrate 1 (Rac1) signaling axis that promotes metastasis in melanoma, colon, and breast cancer cells. Here, we evaluated whether the anti-metastatic effect of AT2R is connected to inhibition of this pathway. We found that murine melanoma B16F10 cells expressed AT2R, while MDA-MB-231 human breast cancer cells did not. AT2R activation blocked migration, transendothelial migration, and metastasis of B16F10(cav-1) cells, and this effect was lost when AT2R was silenced. Additionally, AT2R activation reduced transendothelial migration of A375 human melanoma cells expressing CAV1. The relevance of AT2R was further underscored by showing that overexpression of the AT2R in MDA-MB-231 cells decreased migration. Moreover, AT2R activation increased non-receptor protein tyrosine phosphatase 1B (PTP1B) activity, decreased phosphorylation of CAV1 on tyrosine-14 as well as Rab5/Rac1 activity, and reduced lung metastasis of B16F10(cav-1) cells in C57BL/6 mice. Thus, AT2R activation reduces migration, invasion, and metastasis of cancer cells by PTP1B-mediated CAV1 dephosphorylation and inhibition of the CAV1/Rab5/Rac-1 pathway. In doing so, these observations open up interesting, novel therapeutic opportunities to treat metastatic cancer disease.
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    Autophagy and oxidative stress in non-communicable diseases: A matter of the inflammatory state?
    (2018) Pena-Oyarzun, Daniel; Bravo-Sagua, Roberto; Diaz-Vega, Alexis; Aleman, Larissa; Chiong, Mario; Garcia, Lorena; Bambs S., Claudia; Troncoso, Rodrigo; Cifuentes, Mariana; Morselli, Eugenia; Ferreccio Readi, Catterina; Quest, Andrew F. G.; Criollo, Alfred
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    Enhanced caveolin-1 expression increases migration, anchorage-independent growth and invasion of endometrial adenocarcinoma cells
    (2015) Diaz Valdivia, Natalia.; Owen, Gareth Ivor; Bravo, Denisse.; Huerta, Hernán.; Henriquez, Soledad.; Gabler, Fernando.; Vega, Margarita.; Romero, Carmen.; Calderon, Claudia.; Leyton, Lisette.; Quest, Andrew F. G.
    Abstract Background Caveolin-1 (CAV1) has been implicated both in tumor suppression and progression, whereby the specific role appears to be context dependent. Endometrial cancer is one of the most common malignancies of the female genital tract; however, little is known about the role of CAV1 in this disease. Methods Here, we first determined by immunohistochemistry CAV1 protein levels in normal proliferative human endometrium and endometrial tumor samples. Then using two endometrial cancer cell lines (ECC: Ishikawa and Hec-1A) we evaluated mRNA and protein levels of CAV1 by real time qPCR and Western blot analysis, respectively. The role of CAV1 expression in ECC malignancy was further studied by either inducing its expression in endometrial cancer cells with the tumor promotor 12-O-tetradecanoyl-phorbol-13-acetate (4β-TPA) or decreasing expression using short-hairpin RNA constructs, and then evaluating the effects of these changes on ECC proliferation, transmigration, matrigel invasion, and colony formation in soft agar. Results Immunohistochemical analysis of endometrial epithelia revealed that substantially higher levels of CAV1 were present in endometrial tumors than the normal proliferative epithelium. Also, in Ishikawa and Hec-1A endometrial cancer cells CAV1 expression was readily detectable. Upon treatment with 4β-TPA CAV1 levels increased and coincided with augmented cell transmigration, matrigel invasion, as well as colony formation in soft agar. Reduction of CAV1 expression using short-hairpin RNA constructs ablated these effects in both cell types whether treated or not with 4β-TPA. Alternatively, CAV1 expression appeared not to modulate significantly proliferation of these cells. Conclusion Our study shows that elevated CAV1, observed in patients with endometrial cancer, is linked to enhanced malignancy of endometrial cancer cells, as evidenced by increased migration, invasion and anchorage-independent growth.
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    ER-to-mitochondria miscommunication and metabolic diseases
    (2015) López Crisosto, Camila; Bravo Sagua, Roberto; Rodriguez Peña, Marcelo; Mera, Claudia; Castro Gálvez, Pablo Federico; Quest, Andrew F. G.; Rothermel, Beverly A.; Cifuentes, Mariana; Lavandero, Sergio
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    Helicobacter pylori Infection Is Associated with Decreased Expression of SLC5A8, a Cancer Suppressor Gene, in Young Children
    (2016) Orellana Manzano, Andrea; O’Ryan, Miguel G.; Lagomarcino, Anne J.; George, Sergio; Muñoz, Mindy S.; Mamani, Nora; Serrano Honeyman, Carolina; Harris D., Paul R.; Ramilo, Octavio; Mejías, Asunción; Torres, Juan P.; Lucero, Yalda; Quest, Andrew F. G.; Orellana Manzano, Andrea; O’Ryan, Miguel G.; Lagomarcino, Anne J.; George, Sergio; Muñoz, Mindy S.; Mamani, Nora; Serrano Honeyman, Carolina; Harris D., Paul R.; Ramilo, Octavio; Mejías, Asunción; Torres, Juan P.; Lucero, Yalda; Quest, Andrew F. G.
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    Helicobacter pylori-induced inflammation and epigenetic changes during gastric carcinogenesis
    (Baishideng Publishing Group Inc., 2015) Valenzuela, Manuel A.; Canales, Jimena; Corvalán Rodríguez, Alejandro; Quest, Andrew F. G.
    The sequence of events associated with the development of gastric cancer has been described as "the gastric precancerous cascade". This cascade is a dynamic process that includes lesions, such as atrophic gastritis, intestinal metaplasia and dysplasia. According to this model, Helicobacter pylori (H. pylori) infection targets the normal gastric mucosa causing non-atrophic gastritis, an initiating lesion that can be cured by clearing H. pylori with antibiotics or that may then linger in the case of chronic infection and progress to atrophic gastritis. The presence of virulence factors in the infecting H. pylori drives the carcinogenesis process. Independent epidemiological and animal studies have confirmed the sequential progression of these precancerous lesions. Particularly long-term follow-up studies estimated a risk of 0.1% for atrophic gastritis/intestinal metaplasia and 6% in case of dysplasia for the long-term development of gastric cancer. With this in mind, a better understanding of the genetic and epigenetic changes associated with progression of the cascade is critical in determining the risk of gastric cancer associated with H. pylori infection. In this review, we will summarize some of the most relevant mechanisms and focus predominantly but not exclusively on the discussion of gene promoter methylation and miRNAs in this context.
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    Helicobacter pylori-Induced Loss of the Inhibitor-of-Apoptosis Protein Survivin Is Linked to Gastritis and Death of Human Gastric Cells
    (OXFORD UNIV PRESS INC, 2010) Valenzuela, Manuel; Perez Perez, Guillermo; Corvalan, Alejandro H.; Carrasco, Gonzalo; Urra, Hery; Bravo, Denisse; Toledo, Hector; Quest, Andrew F. G.
    Helicobacter pylori infects the human stomach and modifies signaling pathways that affect gastric epithelial cell proliferation and viability. Chronic exposure to this pathogen contributes to the onset of gastric atrophy, an early event in the genesis of gastric cancer associated with H. pylori infection. Susceptibility to H. pylori-induced cell death ultimately depends on the presence of protective host cell factors. Although expression of the inhibitor-of-apoptosis protein survivin in adults is frequently linked to the development of cancer, evidence indicating that the protein is present in normal gastric mucosa is also available. Thus, we investigated in human gastric tissue samples and cell lines whether H. pylori infection is linked to loss of survivin and increased cell death. Our results show that infection with H. pylori decreased survivin protein levels in the mucosa of patients with gastritis. Furthermore, survivin down-regulation correlated with apoptosis and loss of cell viability in gastrointestinal cells cocultured with different H. pylori strains. Finally, overexpression of survivin in human gastric cells was sufficient to reduce cell death after infection. Taken together, these findings implicate survivin as an important survival factor in the gastric mucosa of humans.
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    Progesterone Utilizes Distinct Membrane Pools of Tissue Factor to Increase Coagulation and Invasion and These Effects are Inhibited by TFPI
    (WILEY, 2011) Henriquez, Soledad; Calderon, Claudia; Quezada, Marisol; Oliva, Barbara; Loreto Bravo, Maria; Aranda, Evelyn; Kato, Sumie; Cuello, Mauricio A.; Gutierrez, Jorge; Quest, Andrew F. G.; Owen, Gareth I.
    Tissue factor (TF) serving as the receptor for coagulation factor VII (FVII) initiates the extrinsic coagulation pathway. We previously demonstrated that progesterone increases TF, coagulation and invasion in breast cancer cell lines. Herein, we investigated if tissue factor pathway inhibitor (TFPI) could down-regulate progesterone-increased TF activity in these cells. Classically, TFPI redistributes TF-FVII-FX-TFPI in an inactive quaternary complex to membrane associated lipid raft regions. Herein, we demonstrate that TF increased by progesterone is localized to the heavy membrane fraction, despite progesterone-increased coagulation originating almost exclusively from lipid raft domains, where TF levels are extremely low. The progesterone increase in coagulation is not a rapid effect, but is progesterone receptor (PR) dependent and requires protein synthesis. Although a partial relocalization of TF occurs, TFPI does not require the redistribution to lipid rafts to inhibit coagulation or invasion. Inhibition by TFPI and anti-TF antibodies in lipid raft membrane fractions confirmed the dependence on TF for progesterone-mediated coagulation. Through the use of pathway inhibitors, we further demonstrate that the TF up-regulated by progesterone is not coupled to the progesterone increase in TF-mediated coagulation. However, the progesterone up-regulated TF protein may be involved in progesterone-mediated breast cancer cell invasion, which TFPI also inhibits. J. Cell. Physiol. 226: 3278-3285, 2011. (C) 2011 Wiley Periodicals, Inc.
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    Protein kinase B (AKT) upregulation and Thy‑1‑αvβ3 integrin‑induced phosphorylation of Connexin43 by activated AKT in astrogliosis
    (2023) Pérez-Núñez, Ramón; Chamorro, Alejandro; González, María F.; Contreras, Pamela; Artigas Barrenechea, Rocío; Corvalán R., Alejandro; van Zundert, Brigitte; Reyes, Christopher; Moya, Pablo R.; Avalos, Ana M.; Schneider, Pascal; Quest, Andrew F. G.; Leyton, Lisette
    Background: In response to brain injury or inflammation, astrocytes undergo hypertrophy, proliferate, and migrate to the damaged zone. These changes, collectively known as "astrogliosis", initially protect the brain; however, astrogliosis can also cause neuronal dysfunction. Additionally, these astrocytes undergo intracellular changes involving alterations in the expression and localization of many proteins, including αvβ3 integrin. Our previous reports indicate that Thy-1, a neuronal glycoprotein, binds to this integrin inducing Connexin43 (Cx43) hemichannel (HC) opening, ATP release, and astrocyte migration. Despite such insight, important links and molecular events leading to astrogliosis remain to be defined. Methods: Using bioinformatics approaches, we analyzed different Gene Expression Omnibus datasets to identify changes occurring in reactive astrocytes as compared to astrocytes from the normal mouse brain. In silico analysis was validated by both qRT-PCR and immunoblotting using reactive astrocyte cultures from the normal rat brain treated with TNF and from the brain of a hSOD1G93A transgenic mouse model. We evaluated the phosphorylation of Cx43 serine residue 373 (S373) by AKT and ATP release as a functional assay for HC opening. In vivo experiments were also performed with an AKT inhibitor (AKTi). Results: The bioinformatics analysis revealed that genes of the PI3K/AKT signaling pathway were among the most significantly altered in reactive astrocytes. mRNA and protein levels of PI3K, AKT, as well as Cx43, were elevated in reactive astrocytes from normal rats and from hSOD1G93A transgenic mice, as compared to controls. In vitro, reactive astrocytes stimulated with Thy-1 responded by activating AKT, which phosphorylated S373Cx43. Increased pS373Cx43 augmented the release of ATP to the extracellular medium and AKTi inhibited these Thy-1-induced responses. Furthermore, in an in vivo model of inflammation (brain damage), AKTi decreased the levels of astrocyte reactivity markers and S373Cx43 phosphorylation. Conclusions: Here, we identify changes in the PI3K/AKT molecular signaling network and show how they participate in astrogliosis by regulating the HC protein Cx43. Moreover, because HC opening and ATP release are important in astrocyte reactivity, the phosphorylation of Cx43 by AKT and the associated increase in ATP release identify a potential therapeutic window of opportunity to limit the adverse effects of astrogliosis.
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    Regulation of cardiomyocyte autophagy by calcium
    (2016) Shaikh, Soni; Troncoso, Rodrigo; Criollo, Alfredo; Bravo Sagua, Roberto; García, Lorena; Morselli, Eugenia; Cifuentes, Mariana; Quest, Andrew F. G.; Hill, Joseph A.; Lavandero, Sergio