RESUMEN
Small cell lung carcinoma (SCLC) often features the upregulation of the Sonic hedgehog (Shh) pathway leading to activation of Gli transcription factors. SCLC cells secrete bombesin (BBS)-like neuropeptides that act as autocrine growth factors. Here, we show that SCLC tumor samples feature co-expression of Shh and BBS-cognate receptor (gastrin-releasing peptide receptor (GRPR)). We also demonstrate that BBS activates Gli in SCLC cells, which is crucial for BBS-mediated SCLC proliferation, because cyclopamine, an inhibitor of the Shh pathway, hampered the BBS-mediated effects. BBS binding to GRPR stimulated Gli through its downstream Gαq and Gα12/13 GTPases, and consistently, other Gαq and Gα13 coupled receptors (such as muscarinic receptor, m1, and thrombin receptor, PAR-1) and constitutively active GαqQL and Gα12/13QL mutants stimulated Gli. By using cells null for Gαq and Gα12/13, we demonstrate that these G proteins are strictly necessary for Gli activation by BBS. Moreover, by using constitutively active Rho small G-protein (Rho QL) as well as its inhibitor, C3 toxin, we show that Rho mediates G-protein-coupled receptor (GPCR)-, Gαq- and Gα12/13-dependent Gli stimulation. At the molecular level, BBS caused a significant increase in Shh gene transcription and protein secretion that was dependent on BBS-induced GPCR/Gαq-12/13/Rho mediated activation of nuclear factor κB (NFκB), which can stimulate a NF-κB response element in the Shh gene promoter. Our data identify a novel molecular network acting in SCLC linking autocrine BBS and Shh circuitries and suggest Shh inhibitors as novel therapeutic strategies against this aggressive cancer type.
Asunto(s)
Proteínas Hedgehog/fisiología , Neoplasias Pulmonares/patología , Receptores de Bombesina/fisiología , Transducción de Señal/fisiología , Carcinoma Pulmonar de Células Pequeñas/patología , Animales , Bombesina/farmacología , Ácidos Borónicos/farmacología , Bortezomib , Cisplatino/farmacología , Subunidades alfa de la Proteína de Unión al GTP G12-G13/fisiología , Subunidades alfa de la Proteína de Unión al GTP Gq-G11/fisiología , Células HEK293 , Humanos , Neoplasias Pulmonares/tratamiento farmacológico , Ratones , Células 3T3 NIH , Proteínas Oncogénicas/fisiología , Pirazinas/farmacología , Carcinoma Pulmonar de Células Pequeñas/tratamiento farmacológico , Transactivadores/fisiología , Proteína con Dedos de Zinc GLI1RESUMEN
Laryngeal dysplasia is a common clinical concern. Despite major advancements, a significant number of patients with this condition progress to invasive squamous cell carcinoma. Osteopontin (OPN) is a secreted glycoprotein, whose expression is markedly elevated in several types of cancers. We explored OPN as a candidate biomarker for laryngeal dysplasia. To this aim, we examined OPN expression in 82 cases of dysplasia and in hyperplastic and normal tissue samples. OPN expression was elevated in all severe dysplasia samples, but not hyperplastic samples, with respect to matched normal mucosa. OPN expression levels correlated positively with degree of dysplasia (P=0.0094) and negatively with disease-free survival (P<0.0001). OPN expression was paralleled by cell surface reactivity for CD44v6, an OPN functional receptor. CD44v6 expression correlated negatively with disease-free survival, as well (P=0.0007). Taken as a whole, our finding identify OPN and CD44v6 as predictive markers of recurrence or aggressiveness in laryngeal intraepithelial neoplasia, and overall, point out an important signalling complex in the evolution of laryngeal dysplasia.
Asunto(s)
Glicoproteínas/análisis , Receptores de Hialuranos/análisis , Enfermedades de la Laringe/patología , Osteopontina/análisis , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/patología , Supervivencia sin Enfermedad , Femenino , Humanos , Inmunohistoquímica , Enfermedades de la Laringe/metabolismo , Masculino , Persona de Mediana Edad , Neoplasias Faríngeas/metabolismo , Neoplasias Faríngeas/patología , Lesiones Precancerosas/metabolismo , Lesiones Precancerosas/patología , PronósticoRESUMEN
This is a case report of granulocytic sarcoma occurring as a nasal lesion prior to the onset of acute myelogenous leukaemia (AML). To understand this case in more detail, we used 40,000 human cDNA microarray to identify the gene expression patterns of nonleukaemic stage bone marrow (BM), AML stage BM and AML stage peripheral blood cells and subsequently define the molecular basis of this disease progression. Of significance, we have tracked the expression profile of BM samples during the course of nonleukaemic to leukaemic progression, and identified a number of genes that may account for the growth potential of leukaemia cells and indicate poor prognosis of this case.
Asunto(s)
Regulación Leucémica de la Expresión Génica/genética , Leucemia Mieloide Aguda/genética , Neoplasias Nasales/genética , Sarcoma Mieloide/genética , Anciano de 80 o más Años , Progresión de la Enfermedad , Regulación hacia Abajo/genética , Resultado Fatal , Femenino , Humanos , Leucemia Mieloide Aguda/patología , Neoplasias Nasales/patología , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Sarcoma Mieloide/patología , Regulación hacia Arriba/genéticaRESUMEN
Thyroid papillary carcinomas are characterized by RET/PTC rearrangements that cause the tyrosine kinase domain of the RET receptor to fuse with N-terminal sequences encoded by heterologous genes. This results in the aberrant expression of a ligand-independent and constitutively active RET kinase. We analysed actin reorganization induced by the RET/PTC1 oncogene in PC Cl 3 rat thyroid epithelial cells. Differently from oncogenes Src, Ras and Raf, RET/PTC1 caused actin filaments to form prominent stress fibers. Moreover, stress fibers were identified in human thyroid papillary carcinoma cell lines harboring RET/PTC1 rearrangements but not in thyroid carcinoma cells negative for RET/PTC rearrangements. RET/MEN 2A, a constitutively active but unrearranged membrane-bound RET oncoprotein, did not induce stress fibers in PC Cl 3 cells. Induction of stress fibers by RET/PTC1 was restricted to thyroid cells; it did not occur in NIH3T3 fibroblasts or MCF7 mammary cells. RET/PTC1-mediated stress fiber formation depended on Rho but not Rac small GTPase activity. In addition, inhibition of Rho, but not of Rac, caused apoptosis of RET/PTC1-expressing thyroid cells. We conclude that Rho is implicated in the actin reorganization and cell survival mediated by the chimeric RET/PTC1 oncogene in thyroid epithelial cells, both phenotypes being cell type- and oncogene type-specific.
Asunto(s)
Carcinoma Papilar/patología , Proteínas de Drosophila , Proteínas de Fusión Oncogénica/fisiología , Transducción de Señal/fisiología , Fibras de Estrés/fisiología , Glándula Tiroides/citología , Neoplasias de la Tiroides/patología , Proteínas de Unión al GTP rho/fisiología , Células 3T3 , Actinas/metabolismo , Adenocarcinoma/patología , Animales , Apoptosis , Neoplasias de la Mama/patología , Línea Celular , Línea Celular Transformada , Supervivencia Celular , Replicación del ADN , Dimerización , Femenino , Humanos , Sistema de Señalización de MAP Quinasas , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Ratones , Neoplasia Endocrina Múltiple Tipo 2a/genética , Neoplasia Endocrina Múltiple Tipo 2a/metabolismo , Invasividad Neoplásica , Proteínas de Neoplasias/metabolismo , Especificidad de Órganos , Fenotipo , Proteínas Tirosina Quinasas , Proteínas Proto-Oncogénicas , Proteínas Proto-Oncogénicas c-ret , Ratas , Proteínas Tirosina Quinasas Receptoras , Proteínas Recombinantes de Fusión/fisiología , Transfección , Células Tumorales CultivadasRESUMEN
The RET tyrosine kinase is a functional receptor for neurotrophic ligands of the glial cell line-derived neurotrophic factor (GDNF) family. Loss of function of RET is associated with congenital megacolon or Hirschsprung's disease, whereas germ-line point mutations causing RET activation are responsible for multiple endocrine neoplasia type 2 (MEN2A, MEN2B, and familial medullary thyroid carcinoma) syndromes. Here we show that the expression of a constitutively active RET-MEN2A oncogene promotes survival of rat pheochromocytoma PC12 cells upon growth factor withdrawal. Moreover, we show that the RET-MEN2A-mediated survival depends on signals transduced by the phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) cascades. Thus, in PC12 cells, RET-MEN2A associates with the PI3K regulatory subunit p85 and promotes activation of Akt (also referred to as protein kinase B) in a PI3K-dependent fashion; in addition, RET-MEN2A promotes MAPK activation. PI3K recruitment and Akt activation as well as MAPK activation depend on RET-MEN2A tyrosine residue 1062. As a result, tyrosine 1062 of RET-MEN2A is essential for RET-MEN2A-mediated survival of PC12 cells cultured in growth factor-depleted media.
Asunto(s)
Proteínas de Drosophila , Sistema de Señalización de MAP Quinasas , Proteínas Serina-Treonina Quinasas , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Tirosina Quinasas Receptoras/metabolismo , Tirosina/metabolismo , Animales , Western Blotting , Supervivencia Celular , Cromonas/farmacología , Medio de Cultivo Libre de Suero , Fragmentación del ADN , Activación Enzimática , Inhibidores Enzimáticos/farmacología , Flavonoides/farmacología , Receptores del Factor Neurotrófico Derivado de la Línea Celular Glial , Etiquetado Corte-Fin in Situ , Ligandos , Morfolinas/farmacología , Neoplasia Endocrina Múltiple Tipo 2a/genética , Neoplasia Endocrina Múltiple Tipo 2a/metabolismo , Células PC12 , Fosfatidilinositol 3-Quinasas/metabolismo , Pruebas de Precipitina , Isoformas de Proteínas , Proteínas Proto-Oncogénicas/química , Proteínas Proto-Oncogénicas c-akt , Proteínas Proto-Oncogénicas c-ret , Ratas , Proteínas Tirosina Quinasas Receptoras/química , Transducción de Señal , TransfecciónRESUMEN
The Akt/protein kinase B serine/threonine kinase is a downstream effector of phosphoinositide 3-kinase (PI3K). Akt is an important component of mitogenic and antiapoptotic signaling pathways and is implicated in neoplastic transformation. Thyroid cells in culture retain a differentiated phenotype consisting of epithelial cell morphology and the expression of several tissue-specific genes. The survival and proliferation of these cells depend on thyrotropin and a mixture of five additional hormones that includes insulin. The regulation of proliferation and the expression of the thyroid differentiation program are intimately connected processes. As a result, oncogenes that induce hormone-independent proliferation invariably impair the expression of the thyroid-specific differentiation markers. Given that thyrotropin and insulin stimulate Akt activation in thyroid cells, we set out to determine the effects of Akt on thyroid cell proliferation, survival, and differentiation. To this end, we expressed constitutively active myristylated Akt (myrAkt) in PC Cl 3 thyroid cells. The myrAkt-expressing cells continued to proliferate, even in the absence of hormones, and they were resistant to programmed cell death induced by starvation. These effects were paralleled by the induction of the G1 cyclins D3 and E and by the inhibition of induction of the proapoptotic Fas, Fas ligand, and BAD genes in starved cells. However, in marked contrast with several other oncogenes, myrAkt did not interfere with the expression of thyroid differentiation functions. These results unveil the existence of an Akt-triggered thyroid cell pathway that modulates proliferation and survival without affecting the expression of the thyroid cell differentiated phenotype.