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1.
Am J Pathol ; 180(3): 1202-1214, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-22245727

RESUMEN

The aim of the present work was to identify protein tyrosine phosphatases (PTPs) as novel, candidate tumor suppressor genes in lung cancer. Among the 38 PTPs in the human genome that show specificity for phosphotyrosine, we identified six PTPs by quantitative RT-PCR whose mRNA expression levels were significantly down-regulated in lung cancer-derived cell lines (ie, PTPRE, PTPRF, PTPRU, PTPRK, PTPRD, and PTPN13). After validation in primary samples of non-small cell lung cancer (NSCLC), we selected PTPN13 for further studies. The results presented here demonstrate that PTPN13 is a candidate tumor suppressor gene that is frequently inactivated in NSCLC through the loss of either mRNA and protein expression (64/87, 73%) or somatic mutation (approximately 8%). Loss of PTPN13 expression was apparently due to the loss of one or both copies of the PTPN13 locus at 4q (approximately 26% double deletion and approximately 37% single deletion) but not to promoter methylation. Finally, the manipulation of PTPN13 expression in lung cancer cells (ie, NCI-H292, A549) demonstrated that PTPN13 negatively regulates anchorage-dependent and anchorage-independent growth in vitro and restrains tumorigenicity in vivo, possibly through the control of the tyrosine phosphorylation of both EGFR and HER2. In conclusion, the expression screening of PTPs in lung cancer reported here has identified PTPN13 as a novel candidate tumor suppressor in NSCLC whose loss increases signaling from epidermal growth factor receptor and HER2 tyrosine kinase receptors.


Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas/genética , Eliminación de Gen , Genes Supresores de Tumor , Neoplasias Pulmonares/genética , Proteína Tirosina Fosfatasa no Receptora Tipo 13/genética , Adulto , Anciano , Anciano de 80 o más Años , Animales , Carcinoma de Pulmón de Células no Pequeñas/metabolismo , Línea Celular Tumoral , Metilación de ADN , Receptores ErbB/metabolismo , Femenino , Humanos , Neoplasias Pulmonares/metabolismo , Masculino , Ratones , Ratones Desnudos , Persona de Mediana Edad , Proteína Tirosina Fosfatasa no Receptora Tipo 13/metabolismo , Proteína Tirosina Fosfatasa no Receptora Tipo 13/fisiología , ARN/metabolismo , ARN Interferente Pequeño/genética , Receptor ErbB-2/metabolismo , Transducción de Señal , Ensayos Antitumor por Modelo de Xenoinjerto , Adulto Joven
2.
Mol Cancer Ther ; 18(2): 482-493, 2019 02.
Artículo en Inglés | MEDLINE | ID: mdl-30425132

RESUMEN

The CDK inhibitor, p27kip1, encoded by the Cdkn1b gene can negatively modulate cell proliferation. The control of p27 activity during the cell cycle is regulated at multiple levels, including transcription, translation, and protein stability. The last residue of p27 (threonine 198 in human, threonine 197 in mouse) is involved in the control of protein stability. We have generated a murine knock-in model (Cdkn1b T197A) in which threonine 197 is replaced by alanine, which renders p27 protein highly unstable due to a high rate of proteasomal degradation. Expectedly, Cdkn1b T197A/T197A mice present with increased body size and weight, organomegaly, and multiple organ hyperplasia, similar to what is observed in Cdkn1b KO/KO mice. We investigated the effects exerted by the restoration of normal levels of p27 protein in the tissue of Cdkn1b T197A/T197A mice. We found that proteasome inhibition with bortezomib rescues the hyperplasia induced by the lack of p27 expression in Cdkn1b T197A/T197A but not in Cdkn1b KO/KO mice. However, BAY 11-7082, a proteasome inhibitor that stabilizes IκB but not p27, fails to rescue hyperplasia in Cdkn1b T197A/T197A mice. Bortezomib increases p27 half-life and reduces the proliferation in MEFs derived from Cdkn1b T197A/T197A but not from Cdkn1b WT/WT mice, whereas BAY 11-7082 had no effect on the protein levels of p27 and on the proliferation rate of Cdkn1b T197A/T197A MEFs.The results presented here demonstrate that Cdkn1b T197A/T197A mice represent an attractive in vivo model to investigate whether the targeting of p27 degradation machinery might prove beneficial in the treatment of a variety of human proliferative disorders caused by increased turnover of p27 protein.


Asunto(s)
Sustitución de Aminoácidos , Bortezomib/farmacología , Inhibidor p27 de las Quinasas Dependientes de la Ciclina/química , Inhibidor p27 de las Quinasas Dependientes de la Ciclina/genética , Modelos Animales , Animales , Técnicas de Sustitución del Gen , Hiperplasia , Ratones , Nitrilos/farmacología , Complejo de la Endopetidasa Proteasomal/metabolismo , Estabilidad Proteica , Proteolisis , Sulfonas/farmacología
3.
Cell Death Dis ; 8(6): e2842, 2017 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-28569781

RESUMEN

Mitochondria are the powerhouses of energy production and the sites where metabolic pathway and survival signals integrate and focus, promoting adaptive responses to hormone stimulation and nutrient availability. Increasing evidence suggests that mitochondrial bioenergetics, metabolism and signaling are linked to tumorigenesis. AKAP1 scaffolding protein integrates cAMP and src signaling on mitochondria, regulating organelle biogenesis, oxidative metabolism and cell survival. Here, we provide evidence that AKAP1 is a transcriptional target of Myc and supports the growth of cancer cells. We identify Sestrin2, a leucine sensor and inhibitor of the mammalian target of rapamycin (mTOR), as a novel component of the complex assembled by AKAP1 on mitochondria. Downregulation of AKAP1 impaired mTOR pathway and inhibited glioblastoma growth. Both effects were reversed by concomitant depletion of AKAP1 and sestrin2. High levels of AKAP1 were found in a wide variety of high-grade cancer tissues. In lung cancer, AKAP1 expression correlates with high levels of Myc, mTOR phosphorylation and reduced patient survival. Collectively, these data disclose a previously unrecognized role of AKAP1 in mTOR pathway regulation and cancer growth. AKAP1/mTOR signal integration on mitochondria may provide a new target for cancer therapy.


Asunto(s)
Proteínas de Anclaje a la Quinasa A/genética , Neoplasias Encefálicas/genética , Regulación Neoplásica de la Expresión Génica , Neoplasias Pulmonares/genética , Mitocondrias/genética , Proteínas Proto-Oncogénicas c-myc/genética , Serina-Treonina Quinasas TOR/genética , Proteínas de Anclaje a la Quinasa A/antagonistas & inhibidores , Proteínas de Anclaje a la Quinasa A/metabolismo , Animales , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patología , Línea Celular Tumoral , Proliferación Celular , Células Epiteliales/metabolismo , Células Epiteliales/patología , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/mortalidad , Neoplasias Pulmonares/patología , Masculino , Ratones Desnudos , Mitocondrias/metabolismo , Trasplante de Neoplasias , Neuroglía/metabolismo , Neuroglía/patología , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Unión Proteica , Proteínas Proto-Oncogénicas c-myc/metabolismo , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Transducción de Señal , Análisis de Supervivencia , Serina-Treonina Quinasas TOR/metabolismo , Transcripción Genética
4.
Oncotarget ; 6(37): 39634-50, 2015 Nov 24.
Artículo en Inglés | MEDLINE | ID: mdl-26053093

RESUMEN

The hotspot E17K mutation in the pleckstrin homology domain of AKT1 occurs in approximately 0.6-2% of human lung cancers. In this manuscript, we sought to determine whether this AKT1 variant is a bona-fide activating mutation and plays a role in the development of lung cancer. Here we report that in immortalized human bronchial epithelial cells (BEAS-2B cells) mutant AKT1-E17K promotes anchorage-dependent and -independent proliferation, increases the ability to migrate, invade as well as to survive and duplicate in stressful conditions, leading to the emergency of cells endowed with the capability to form aggressive tumours at high efficiency. We provide also evidence that the molecular mechanism whereby AKT1-E17K is oncogenic in lung epithelial cells involves phosphorylation and consequent cytoplasmic delocalization of the cyclin-dependent kinase (cdk) inhibitor p27. In agreement with these results, cytoplasmic p27 is preferentially observed in primary NSCLCs with activated AKT and predicts poor survival.


Asunto(s)
Células Epiteliales/metabolismo , Neoplasias Pulmonares/genética , Mutación Missense , Proteínas Proto-Oncogénicas c-akt/genética , Animales , Western Blotting , Bronquios/citología , Adhesión Celular/genética , Línea Celular , Línea Celular Tumoral , Movimiento Celular/genética , Proliferación Celular/genética , Supervivencia Celular/genética , Inhibidor p27 de las Quinasas Dependientes de la Ciclina/metabolismo , Humanos , Estimación de Kaplan-Meier , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patología , Ratones Desnudos , Microscopía Fluorescente , Persona de Mediana Edad , Fosforilación , Pronóstico , Proteínas Proto-Oncogénicas c-akt/metabolismo , Imagen de Lapso de Tiempo , Trasplante Heterólogo
5.
Cell Cycle ; 11(8): 1583-92, 2012 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-22441823

RESUMEN

In this manuscript, we present experimental evidence that PKCs phosphorylate p27 at T198 in vitro and in vivo, resulting in p27 stabilization and cell cycle arrest in MCF-7 and HeLa cells. Our findings indicate that (1) recombinant PKCα, ßII, δ, η and θ isoforms phosphorylate, in in vitro kinase assays, wild-type recombinant p27 protein expressed in E. coli and wild-type p27 protein immunoprecpitated from transfected HEK-293 cells but not the T198A mutant, (2) adoptive expressed PKCα and δ phosphorylate both transfected and endogenous p27 at T198 in HEK-293 cells, (3) T198 phosphorylation of transfected and endogenous p27 is increased by PKC activators [Phorbol 12-myristate 13-acetate (PMA)] and suppressed by PKC inhibitors (Rottlerin A, G06976, Calphostin C), (4) in parallel with increased T198 phosphorylation, PMA induces stabilization of p27 protein in HeLa cells, whereas PKC inhibitors induce a decrease in p27 stability and, finally, (5) PMA-induced p27 upregulation is necessary for growth arrest of HeLa and MCF-7 cells induced by PKC activation by PMA.   Overall, these results suggest that PKC-dependent upregulation of p27 induced by its phosphorylation at T198 represents a mechanism that mediates growth arrest promoted by PMA and provide novel insights on the ability of different PKC isoforms to play a role in controlling cell cycle progression.


Asunto(s)
Inhibidor p27 de las Quinasas Dependientes de la Ciclina/metabolismo , Proteína Quinasa C/metabolismo , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Puntos de Control del Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Inhibidor p27 de las Quinasas Dependientes de la Ciclina/antagonistas & inhibidores , Inhibidor p27 de las Quinasas Dependientes de la Ciclina/genética , Células HEK293 , Células HeLa , Humanos , Naftalenos/química , Naftalenos/farmacología , Fosforilación , Isoformas de Proteínas/antagonistas & inhibidores , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteína Quinasa C/antagonistas & inhibidores , Proteína Quinasa C/genética , Proteínas Recombinantes/antagonistas & inhibidores , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Acetato de Tetradecanoilforbol/análogos & derivados , Acetato de Tetradecanoilforbol/química , Acetato de Tetradecanoilforbol/farmacología , Transfección , Regulación hacia Arriba
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