RESUMEN

A six-month-old Labrador retriever presented for investigation of a colonic mass identified as an incidental finding during exploratory coeliotomy. Computed tomography identified a lesion in the colon which occupied part of its lumen and shared blood supply with the remainder of the colon. The lesion was suspected to be a colonic duplication and it was excised by segmental colectomy during exploratory coeliotomy. Histopathology from the excised colon confirmed the diagnosis of a colonic duplication. The dog recovered uneventfully and had no complications. To the authors' knowledge, this is the first report of an asymptomatic, spherical, communicating colonic duplication and the first report to describe segmental colectomy for the management of this condition in veterinary patients.

Asunto(s)

Colectomía/veterinaria , Colon/anomalías , Colon/cirugía , Perros/anomalías , Animales , Perros/cirugía , Tomografía Computarizada por Rayos X/métodos , Tomografía Computarizada por Rayos X/veterinaria

RESUMEN

The adaptor protein p140Cap/SNIP is a novel Src-binding protein that regulates Src activation through C-terminal Src kinase (Csk). Here, by gain and loss of function approaches in breast and colon cancer cells, we report that p140Cap immobilizes E-cadherin at the cell membrane and inhibits EGFR and Erk1/2 signalling, blocking scatter and proliferation of cancer cells. p140Cap-dependent regulation of E-cadherin/EGFR cross-talk and cell motility is due to the inhibition of Src kinase. However, rescue of Src activity is not sufficient to restore Erk1/2 phosphorylation and proliferation. Indeed, p140Cap also impairs Erk1/2 phosphorylation by affecting Ras activity, downstream to the EGFR. In conclusion, p140Cap stabilizes adherens junctions and inhibits EGFR and Ras signalling through the dual control of both Src and Ras activities, thus affecting crucial cancer properties such as invasion and growth. Interestingly, p140Cap expression is lost in more aggressive human breast cancers, showing an inverse correlation with EGFR expression. Therefore, p140Cap mechanistically behaves as a tumour suppressor that inhibits signalling pathways leading to aggressive phenotypes.

Asunto(s)

Proteínas Adaptadoras del Transporte Vesicular/metabolismo , Cadherinas/metabolismo , Movimiento Celular , Receptores ErbB/metabolismo , Neoplasias/patología , Receptor Cross-Talk , Transducción de Señal , Proteínas ras/metabolismo , Animales , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Cadherinas/química , Línea Celular Tumoral , Membrana Celular/metabolismo , Proliferación Celular , Factor de Crecimiento Epidérmico/farmacología , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Ratones , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , Invasividad Neoplásica , Neoplasias/genética , Neoplasias/metabolismo , Estabilidad Proteica , Transducción de Señal/efectos de los fármacos , Familia-src Quinasas/metabolismo

RESUMEN

Loss of E-cadherin-mediated cell-cell junctions has been correlated with cancer cell invasion and poor patient survival. p120-catenin has emerged as a key player in promoting E-cadherin stability and adherens junction integrity and has been proposed as a potential invasion suppressor by preventing release of cells from the constraints imposed by cadherin-mediated cell-cell adhesion. However, it has been proposed that tyrosine phosphorylation of p120 may contribute to cadherin-dependent junction disassembly during invasion. Here, we use small interfering RNA (siRNA) in A431 cells to show that knockdown of p120 promotes two-dimensional migration of cells. In contrast, p120 knockdown impairs epidermal growth factor-induced A431 invasion into three-dimensional matrix gels or in organotypic culture, whereas re-expression of siRNA-resistant p120, or a p120 isoform that cannot be phosphorylated on tyrosine, restores the collective mode of invasion employed by A431 cells in vitro. Thus, p120 promotes A431 cell invasion in a phosphorylation-independent manner. We show that the collective invasion of A431 cells depends on the presence of cadherin-mediated (P- and E-cadherin) cell-cell contacts, which are lost in cells where p120 expression is knocked down. Furthermore, membranous p120 is maintained in invasive squamous cell carcinomas in tumours suggesting that p120 may be important for the collective invasion of tumours cells in vivo.

Asunto(s)

Carcinoma de Células Escamosas/patología , Moléculas de Adhesión Celular/fisiología , Invasividad Neoplásica , Fosfoproteínas/fisiología , Secuencia de Bases , Cateninas , Moléculas de Adhesión Celular/química , Moléculas de Adhesión Celular/metabolismo , Línea Celular Tumoral , Cartilla de ADN , Factor de Crecimiento Epidérmico/metabolismo , Humanos , Fosfoproteínas/química , Fosfoproteínas/metabolismo , Fosforilación , ARN Interferente Pequeño , Proteínas Recombinantes/metabolismo , Tirosina/metabolismo , Catenina delta

RESUMEN

Cancer cells can invade three-dimensional matrices by distinct mechanisms, recently defined by their dependence on extracellular proteases, including matrix metalloproteinases. Upon treatment with protease inhibitors, some tumour cells undergo a 'mesenchymal to amoeboid' transition that allows invasion in the absence of pericellular proteolysis and matrix degradation. We show here that in HT1080 cells, this transition is associated with weakened integrin-dependent adhesion, consistently reduced cell surface expression of the alpha2beta1 integrin collagen receptor and impaired signalling downstream, as judged by reduced autophosphorylation of focal adhesion kinase (FAK). On examining cancer cells that use defined invasion strategies, we show that distinct from mesenchymal invasion, amoeboid invasion is independent of intracellular calpain 2 proteolytic activity that is usually needed for turnover of integrin-linked adhesions during two-dimensional planar migration. Moreover, an inhibitor of Rho/ROCK signalling, which specifically impairs amoeboid-like invasion, restores cell surface expression of alpha2beta1 integrin, downstream FAK autophosphorylation and calpain 2 sensitivity--features of mesenchymal invasion. These findings link weakened integrin function to a lack of requirement for calpain 2-mediated integrin adhesion turnover during amoeboid invasion. In keeping with the need for integrin adhesion turnover, mesenchymal invasion is uniquely sensitive to Src inhibitors. Thus, the need for a major pathway that controls integrin adhesion turnover defines and distinguishes cancer cell invasion strategies.

Asunto(s)

Calpaína/metabolismo , Integrinas/fisiología , Familia-src Quinasas/metabolismo , Secuencia de Bases , Calpaína/genética , Carcinoma de Pulmón de Células no Pequeñas/patología , Adhesión Celular , Línea Celular Tumoral , Fibrosarcoma/patología , Citometría de Flujo , Humanos , Neoplasias Pulmonares/patología , Mesodermo/enzimología , Mesodermo/fisiología , Mutación Missense , Invasividad Neoplásica , ARN Mensajero/genética , ARN Interferente Pequeño/genética , Familia-src Quinasas/genética

RESUMEN

Integrin-associated focal adhesions not only provide adhesive links between cellular actin and extracellular matrix but also are sites of signal transmission into the cell interior. Many cell responses signal through focal adhesion kinase (FAK), often by integrin-induced autophosphorylation of FAK or phosphorylation by Src family kinases. Here, we used an interfering FAK mutant (4-9F-FAK) to show that Src-dependent FAK phosphorylation is required for focal adhesion turnover and cell migration, by controlling assembly of a calpain 2/FAK/Src/p42ERK complex, calpain activation, and proteolysis of FAK. Expression of 4-9F-FAK in FAK-deficient fibroblasts also disrupts F-actin assembly associated with normal adhesion and spreading. In addition, we found that FAK's ability to regulate both assembly and disassembly of the actin and adhesion networks may be linked to regulation of the protease calpain. Surprisingly, we also found that the same interfering 4-9F-FAK mutant protein causes apoptosis of serum-deprived, transformed cells and suppresses anchorage-independent growth. These data show that Src-mediated phosphorylation of FAK acts as a pivotal regulator of both actin and adhesion dynamics and survival signaling, which, in turn, control apparently distinct processes such as cell migration and anchorage-independent growth. This also highlights that dynamic regulation of actin and adhesions (which include the integrin matrix receptors) is critical to signaling output and biological responses.

Asunto(s)

Actinas/metabolismo , Proteínas Tirosina Quinasas/metabolismo , Familia-src Quinasas/metabolismo , Animales , Apoptosis , Adhesión Celular , Movimiento Celular , Células Cultivadas , Embrión de Pollo , Proteína-Tirosina Quinasas de Adhesión Focal , Modelos Biológicos , Mutagénesis Sitio-Dirigida , Proteína Oncogénica pp60(v-src)/genética , Proteína Oncogénica pp60(v-src)/metabolismo , Fosforilación , Proteínas Tirosina Quinasas/química , Proteínas Tirosina Quinasas/genética , Transducción de Señal , Transformación Genética , Familia-src Quinasas/genética

RESUMEN

The interaction of cells with surrounding matrix and neighbouring cells governs many aspects of cell behaviour. Aside from transmitting signals from the external environment, adhesion receptors also receive signals from the cell interior. Here we review the interrelationship between adhesion receptors, tyrosine kinases (both growth factor receptor and non-receptor) and modulators of the actin cytoskeletal network. Deregulation of many aspects of these signalling pathways in cancer highlights the need for a better understanding of the complexities involved.

Asunto(s)

Actinas/metabolismo , Uniones Adherentes/metabolismo , Integrinas/metabolismo , Neoplasias/metabolismo , Familia-src Quinasas/metabolismo , Animales , Sitios de Unión , Cadherinas/metabolismo , Citoesqueleto/metabolismo , Quinasa 1 de Adhesión Focal , Proteína-Tirosina Quinasas de Adhesión Focal , Humanos , Proteínas Tirosina Quinasas/metabolismo , Proteína Activadora de GTPasa p120/metabolismo

RESUMEN

Several oncogene and tumor-suppressor gene products are known substrates for the calpain family of cysteine proteases, and calpain is required for transformation by v-src and tumor invasion. Thus, we have now addressed whether calpain is generally associated with transformation and how calpain contributes to oncogene function. Our results demonstrate that calpain activity is enhanced upon transformation induced by the v-Src, v-Jun, v-Myc, k-Ras, and v-Fos oncoproteins. Furthermore, elevated calpain activity commonly promotes focal adhesion remodelling, disruption of actin cytoskeleton, morphological transformation, and cell migration, although proteolysis of target substrates (such as focal adhesion kinase, talin, and spectrin) is differently specified by individual oncoproteins. Interestingly, v-Fos differs from other common oncoproteins in not requiring calpain activity for actin/adhesion remodelling or migration of v-Fos transformed cells. However, anchorage-independent growth of all transformed cells is sensitive to calpain inhibition. In addition, elevated calpain activity contributes to oncogene-induced apoptosis associated with transformation by v-Myc. Taken together, these studies demonstrate that calpain activity is necessary for full cellular transformation induced by common oncoproteins, but has distinct roles in oncogenic events induced by individual transforming proteins. Thus, targeting calpain activity may represent a useful general strategy for interfering with activated proto-oncogenes in cancer cells.

Asunto(s)

Calpaína/metabolismo , Transformación Celular Neoplásica , Activación Enzimática/fisiología , Proteínas Oncogénicas/metabolismo , Oncogenes/fisiología , Animales , Apoptosis/fisiología , Adhesión Celular/fisiología , División Celular/fisiología , Movimiento Celular/fisiología , Embrión de Pollo , Citoesqueleto/fisiología , Electroforesis en Gel de Poliacrilamida , Inhibidores Enzimáticos/farmacología , Immunoblotting , Inmunohistoquímica , Proteínas Quinasas Activadas por Mitógenos/fisiología , Cicatrización de Heridas/efectos de los fármacos , Cicatrización de Heridas/fisiología

RESUMEN

Elevated expression and/or activity of c-Src, the prototype of the Src family of protein tyrosine kinases, is associated with the development of human colon cancer. However, despite the known pleiotropic effects of these kinases in promoting (a) cell growth downstream of growth factor receptors, and (b) the dynamic regulation of integrin adhesions in fibroblast model systems, their precise role in epithelial cancer cells is unknown. Here we addressed whether elevated expression and activity of cellular Src alters cell proliferation and/or cell-matrix adhesion in cancer cells from the Fidler model of colorectal metastasis. Although elevated Src correlates with ability to metastasise to the liver after intrasplenic injection, we found that this was not linked to enhanced growth, either in vitro or in vivo as sub-cutaneous tumours. However, elevated Src was associated with enhanced attachment to extracellular matrix. In addition, adhesion to fibronectin, was suppressed by agents that inhibited Src activity, while enforced elevation of Src in non-metastatic cells was sufficient to stimulate adhesion to fibronectin and enhanced assembly of adhesion complexes, without influencing cell growth. Thus, we conclude that one role of elevated Src in human colon cancer cells is to modulate integrin-dependent cell-matrix attachment and formation of adhesion structures, which may, in turn, influence cell motility and integrin-dependent cellular responses.

Asunto(s)

Uniones Célula-Matriz/fisiología , Neoplasias Colorrectales/patología , Proteína Oncogénica pp60(v-src)/metabolismo , Proteínas Tirosina Quinasas/fisiología , Adhesión Celular , Neoplasias Colorrectales/metabolismo , Humanos , Metástasis de la Neoplasia , Proteína Oncogénica pp60(v-src)/antagonistas & inhibidores , Proteínas Tirosina Quinasas/antagonistas & inhibidores , Células Tumorales Cultivadas

RESUMEN

The gut flora is a vast interior ecosystem whose nature is only beginning to be unravelled, due to the emergence of sophisticated molecular tools. Techniques such as 16S ribosomal RNA analysis, polymerase chain reaction amplification and the use of DNA microarrays now facilitate rapid identification and characterization of species resistant to conventional culture and possibly unknown species. Life-long cross-talk between the host and the gut flora determines whether health is maintained or disease intervenes. An understanding of these bacteria-bacteria and bacteria-host immune and epithelial cell interactions is likely to lead to a greater insight into disease pathogenesis. Studies of single organism-epithelial interactions have revealed the large range of metabolic processes that gut bacteria may influence. In inflammatory bowel diseases, bacteria drive the inflammatory process, and genetic predisposition to disease identified to date, such as the recently described NOD2/CARD15 gene variants, may relate to altered bacterial recognition. Extra-intestinal disorders, such as atopy and arthritis, may also have an altered gut milieu as their basis. Clinical evidence is emerging that the modification of this internal environment, using either antibiotics or probiotic bacteria, is beneficial in preventing and treating disease. This natural and apparently safe approach holds great appeal.

Asunto(s)

Fenómenos Fisiológicos Bacterianos , Enfermedades Intestinales/microbiología , Mucosa Intestinal/microbiología , Bacterias/aislamiento & purificación , Humanos , Inmunidad Mucosa , Enfermedades Intestinales/terapia , Mucosa Intestinal/inmunología , Probióticos/uso terapéutico

RESUMEN

v-Src-induced oncogenic transformation is characterized by alterations in cell morphology, adhesion, motility, survival, and proliferation. To further elucidate some of the signaling pathways downstream of v-Src that are responsible for the transformed cell phenotype, we have investigated the role that the calpain-calpastatin proteolytic system plays during oncogenic transformation induced by v-Src. We recently reported that v-Src-induced transformation of chicken embryo fibroblasts is accompanied by calpain-mediated proteolytic cleavage of the focal adhesion kinase (FAK) and disassembly of the focal adhesion complex. In this study we have characterized a positive feedback loop whereby activation of v-Src increases protein synthesis of calpain II, resulting in degradation of its endogenous inhibitor calpastatin. Reconstitution of calpastatin levels by overexpression of exogenous calpastatin suppresses proteolytic cleavage of FAK, morphological transformation, and anchorage-independent growth. Furthermore, calpastatin overexpression represses progression of v-Src-transformed cells through the G(1) stage of the cell cycle, which correlates with decreased pRb phosphorylation and decreased levels of cyclins A and D and cyclin-dependent kinase 2. Calpain 4 knockout fibroblasts also exhibit impaired v-Src-induced morphological transformation and anchorage-independent growth. Thus, modulation of the calpain-calpastatin proteolytic system plays an important role in focal adhesion disassembly, morphological transformation, and cell cycle progression during v-Src-induced cell transformation.

Asunto(s)

Quinasas CDC2-CDC28 , Proteínas de Unión al Calcio/metabolismo , Calpaína/metabolismo , Transformación Celular Neoplásica , Proteína Oncogénica pp60(v-src)/metabolismo , Actinas/metabolismo , Animales , Proteínas de Unión al Calcio/genética , Calpaína/antagonistas & inhibidores , Calpaína/genética , División Celular/fisiología , Tamaño de la Célula , Células Cultivadas , Embrión de Pollo , Ciclina A/metabolismo , Ciclina D , Quinasa 2 Dependiente de la Ciclina , Quinasas Ciclina-Dependientes/metabolismo , Ciclinas/metabolismo , Citoesqueleto/metabolismo , Retroalimentación Fisiológica/fisiología , Fibroblastos/fisiología , Quinasa 1 de Adhesión Focal , Proteína-Tirosina Quinasas de Adhesión Focal , Adhesiones Focales/metabolismo , Genes myc , Genes ras , Inmunohistoquímica , Ratones , Ratones Noqueados , Modelos Biológicos , Proteína Oncogénica p65(gag-jun)/metabolismo , Proteínas Oncogénicas v-fos/metabolismo , Isoformas de Proteínas , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Tirosina Quinasas/metabolismo , Proteína de Retinoblastoma/metabolismo , Temperatura

RESUMEN

BACKGROUND: The ability of a cell to polarize and move is governed by remodeling of the cellular adhesion/cytoskeletal network that is in turn controlled by the Rho family of small GTPases. However, it is not known what signals lie downstream of Rac1 and Cdc42 during peripheral actin and adhesion remodeling that is required for directional migration. RESULTS: We show here that individual members of the Rho family, RhoA, Rac1, and Cdc42, direct the specific intracellular targeting of c-Src tyrosine kinase to focal adhesions, lamellipodia, or filopodia, respectively, and that the adaptor function of c-Src (the combined SH3/SH2 domains coupled to green fluorescent protein) is sufficient for targeting. Furthermore, Src's catalytic activity is absolutely required at these peripheral cell-matrix attachment sites for remodeling that converts RhoA-dependent focal adhesions into smaller focal complexes along Rac1-induced lamellipodia (or Cdc42-induced filopodia). Consequently, cells in which kinase-deficient c-Src occupies peripheral adhesion sites exhibit impaired polarization toward migratory stimuli and reduced motility. Furthermore, phosphorylation of FAK, an Src adhesion substrate, is suppressed under these conditions. CONCLUSIONS: Our findings demonstrate that individual Rho GTPases specify Src's exact peripheral localization and that Rac1- and Cdc42-induced adhesion remodeling and directed cell migration require Src activity at peripheral adhesion sites.

Asunto(s)

Movimiento Celular/fisiología , Polaridad Celular/fisiología , Proteínas de Unión al GTP rho/fisiología , Familia-src Quinasas/fisiología , Transporte Biológico , Adhesión Celular , Proteína-Tirosina Quinasas de Adhesión Focal , Fosforilación , Proteínas Tirosina Quinasas/metabolismo

RESUMEN

Although focal adhesion kinase (FAK) is elevated in epithelial cancers, it is not known whether FAK expression influences tumor development in vivo. We found that fak +/- heterozygous mice display reduced 7,12-dimethylbenz[a]anthracene-induced papilloma formation that correlates with reduced FAK protein expression in the skin. However, the frequency of malignant conversion of papillomas into carcinomas is indistinguishable in fak +/- mice and their wild-type fak +/+ littermates, most likely because papilloma FAK protein expression is elevated to wild-type levels. We also found that keratinocyte FAK protein expression is important for cellular responses downstream of ras in vitro (monitored by extracellular signal-regulated kinase activation after integrin engagement). Because 7,12-dimethylbenz[a]anthracene induces an activating mutation of H-ras, this provides one possible explanation for suppression of papilloma formation when FAK protein is limiting.

Asunto(s)

Dosificación de Gen , Papiloma/enzimología , Proteínas Tirosina Quinasas/biosíntesis , Neoplasias Cutáneas/enzimología , 9,10-Dimetil-1,2-benzantraceno , Animales , Carcinógenos , Femenino , Quinasa 1 de Adhesión Focal , Proteína-Tirosina Quinasas de Adhesión Focal , Regulación Enzimológica de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Queratinocitos/efectos de los fármacos , Queratinocitos/enzimología , Queratinocitos/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Papiloma/inducido químicamente , Papiloma/genética , Proteínas Tirosina Quinasas/genética , Transducción de Señal , Neoplasias Cutáneas/inducido químicamente , Neoplasias Cutáneas/genética , Proteínas ras/fisiología

RESUMEN

The tyrosine kinase oncoprotein v-Src can overcome the requirements for serum growth factors and anchorage which restrain normal cell growth. Here we investigated the biochemical mechanisms whereby v-Src induces quiescent cells to enter S phase in the absence of serum mitogens. Activating a temperature sensitive v-Src in quiescent cells sequentially induced cyclins D1, E and A and also down regulated p27. We addressed whether p27 down regulation was required to activate cyclin D1/CDK4/6 or cyclin E/CDK2 by engineering cells with inducible p27. Both S phase entry and activation of cyclin/CDKs were inhibited by over expression of p27. Using cells engineered with inducible p16 we showed that Cyclin D/CDK4/6 activity was required for v-Src to increase expression of cyclin A but not cyclin E. To determine which downstream kinases mediated these effects of v-Src we added pharmacological inhibitors of phosphatidylinositol 3-kinase (PI3-K), LY294002 or mitogen activated protein kinase kinase (MEK), U0126. PI3-K was required for v-Src to activate MEK and MEK was required for v-Src to increase expression of cyclins D1 and E. However, the MEK inhibitor prevented p27 protein down regulation whereas the PI3-K inhibitor did not. This was because reduced PI3-K activity lead to proteolytic degradation of p27.

Asunto(s)

Ciclo Celular , Proteínas Musculares , Proteína Oncogénica pp60(v-src)/fisiología , Animales , Butadienos/farmacología , Línea Celular , Ciclina A/metabolismo , Ciclina D1/metabolismo , Ciclina E/metabolismo , Quinasas Ciclina-Dependientes/fisiología , Regulación hacia Abajo , Inhibidores Enzimáticos/farmacología , Cinética , MAP Quinasa Quinasa 1 , Proteínas de Microfilamentos/genética , Proteínas de Microfilamentos/metabolismo , Quinasas de Proteína Quinasa Activadas por Mitógenos/antagonistas & inhibidores , Quinasas de Proteína Quinasa Activadas por Mitógenos/fisiología , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Nitrilos/farmacología , Proteína Oncogénica pp60(v-src)/antagonistas & inhibidores , Fosfatidilinositol 3-Quinasas/fisiología , Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Proteínas Serina-Treonina Quinasas/fisiología , ARN Mensajero/biosíntesis , Ratas , Transfección

RESUMEN

We have investigated whether the proteolysis of members of the cGMP binding phosphodiesterases (PDE6, PDE5A1, and PDE10A2) by caspase-3 is modulated by the gamma inhibitor subunit of PDE6. We show here that purified caspase-3 proteolyses PDE6, an enzyme composed of two nonidentical catalytic subunits (termed alpha and beta) with molecular mass of 88 and 84 kDa. The proteolysis of PDE6 produced a single fragment with a molecular mass of 78 kDa. This corresponds to the possible cleavage of the caspase-3 consensus DFVD site (amino acids: 164-168) in the alpha subunit and leads to a 50% decrease in the cGMP hydrolysing activity of the enzyme. The addition of rod PDEgamma to the incubation completely blocked the cleavage of PDE6 by caspase-3. In contrast, rod PDEgamma converted PDE5A1 (molecular mass of 98 kDa) to a better substrate for caspase-3. This resulted in the formation of four major fragments with molecular mass of 82-83, 67, 43, and 34 kDa. In addition, caspase-3 induced an approximately 80% reduction in the activity of a partially purified preparation of PDE5A1 in the presence of rod PDEgamma. Caspase-3 also cleaved PDE10A2 (molecular mass of 95 kDa) to a single 48-kDa fragment. This was consistent with cleavage of the DLFD site (amino acids: 312-315) in PDE10A2. In contrast with both PDE6 and PDE5A1, rod PDEgamma was without effect on this enzyme. These data show that rod PDEgamma interacts with at least two members of the cGMP binding PDE family (PDE5A1 and PDE6) and can exert differential effects on the cleavage of these enzymes by caspase-3.

Asunto(s)

3',5'-GMP Cíclico Fosfodiesterasas/metabolismo , 3',5'-GMP Cíclico Fosfodiesterasas/farmacología , Caspasas/farmacología , GMP Cíclico/metabolismo , Hidrolasas Diéster Fosfóricas/metabolismo , Segmento Externo de la Célula en Bastón/enzimología , 3',5'-GMP Cíclico Fosfodiesterasas/genética , Animales , Secuencia de Bases , Caspasa 3 , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 5 , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 6 , Interacciones Farmacológicas , Pulmón/enzimología , Masculino , Ratones , Datos de Secuencia Molecular , ARN/biosíntesis , Homología de Secuencia de Ácido Nucleico , Testículo/enzimología

RESUMEN

Integrins play an important role in tumour progression by influencing cellular responses and matrix-dependent adhesion. However, the regulation of matrix-dependent adhesion assembly in epithelial cells is poorly understood. We have investigated the integrin and signalling requirements of cell-matrix adhesion assembly in colon carcinoma cells after plating on fibronectin. Adhesion assembly in these, and in the adenoma cells from which they were derived, was largely dependent on alpha v beta 6 integrin and required phosphorylation of FAK on tyrosine-397. The rate of fibronectin-induced adhesion assembly and the expression of both alpha v beta 6 integrin and FAK were increased during the adenoma-to-carcinoma transition. The matrix-dependent adhesion assembly process, particularly the final stages of complex protrusion that is required for optimal cell spreading, required the activity of extracellular signal-regulated kinase (ERK). Furthermore, phosphorylated ERK was targeted to newly forming cell--matrix adhesions in the carcinoma cells but not the adenoma cells, and inhibition of FAK--tyrosine-397 phosphorylation or MEK suppressed the appearance of phosphorylated ERK at peripheral sites. In addition, inhibition of MEK--ERK activation blocked the formation of peripheral actin microspikes that were necessary for the protrusive phase of cell-matrix adhesion assembly. Thus, MEK--ERK--dependent peripheral actin re-organization is required for the full development of integrin-induced adhesions and this pathway is stimulated in an in vitro model of colon cancer progression.

Asunto(s)

Adenoma/patología , Antígenos de Neoplasias , Moléculas de Adhesión Celular/fisiología , Neoplasias del Colon/patología , Células Epiteliales/patología , Integrinas/fisiología , Quinasas de Proteína Quinasa Activadas por Mitógenos/fisiología , Proteínas Tirosina Quinasas/fisiología , Actinas/metabolismo , Adenoma/metabolismo , Animales , Moléculas de Adhesión Celular/metabolismo , Línea Celular Transformada , Neoplasias del Colon/metabolismo , Progresión de la Enfermedad , Células Epiteliales/metabolismo , Fibronectinas/metabolismo , Quinasa 1 de Adhesión Focal , Proteína-Tirosina Quinasas de Adhesión Focal , Adhesiones Focales/fisiología , Humanos , Integrinas/metabolismo , Sistema de Señalización de MAP Quinasas/fisiología , Ratones , Ratones Desnudos , Quinasas de Proteína Quinasa Activadas por Mitógenos/metabolismo , Invasividad Neoplásica , Fosforilación , Proteínas Tirosina Quinasas/metabolismo , Proteínas Tirosina Quinasas Receptoras/metabolismo , Células Tumorales Cultivadas , Regulación hacia Arriba

RESUMEN

The inhibitory gamma subunits of the retinal rod and cone photoreceptor type 6 retinal cyclic guanosine monophosphate phosphodiesterase (PDEgamma) are expressed in non-retinal tissues. Here, we show that PDEgamma interacts with the G-protein-coupled receptor kinase 2 signaling system to regulate the epidermal growth factor- and thrombin-dependent stimulation of p42/p44 mitogen-activated protein kinase in human embryonic kidney 293 cells. This is based upon several lines of evidence. First, the transfection of cells with an antisense rod PDEgamma plasmid construct, which reduced endogenous rod PDEgamma expression, ablated the epidermal growth factor- and thrombin-dependent stimulation of p42/p44 mitogen-activated protein kinase. Second, the transfection of cells with recombinant rod or cone PDEgamma and/or G-protein-coupled receptor kinase 2 increased the stimulation of p42/p44 mitogen-activated protein kinase by epidermal growth factor or thrombin. In contrast, a G-protein-coupled receptor kinase 2 phosphorylation-resistant rod PDEgamma mutant failed to increase the epidermal growth factor- or thrombin-dependent stimulation of p42/p44 mitogen-activated protein kinase and, in fact, functioned as a dominant negative. Thrombin also stimulated the association of endogenous rod PDEgamma with dynamin II, which was increased in cells transfected with rod PDEgamma or G-protein-coupled receptor kinase 2. Dynamin II plays a critical role in regulating endocytosis of receptor signal complexes required for activation of p42/p44 mitogen-activated protein kinase. Therefore, PDEgamma may have an important role in promoting endocytosis of receptor signal complexes leading to the activation of p42/p44 mitogen-activated protein kinase. We conclude that PDEgamma is an entirely novel intermediate regulating mitogenic signaling from both receptor tyrosine kinase and G-protein-coupled receptors in human embryonic kidney 293 cells.

Asunto(s)

3',5'-GMP Cíclico Fosfodiesterasas/metabolismo , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Retina/enzimología , Transducción de Señal , 3',5'-GMP Cíclico Fosfodiesterasas/química , 3',5'-GMP Cíclico Fosfodiesterasas/aislamiento & purificación , Secuencia de Bases , Western Blotting , Línea Celular , Cartilla de ADN , Dinaminas , Activación Enzimática , Factor de Crecimiento Epidérmico/farmacología , GTP Fosfohidrolasas/metabolismo , Humanos , Riñón/citología , Riñón/embriología , Riñón/enzimología , Proteína Quinasa 3 Activada por Mitógenos , Datos de Secuencia Molecular , Fosforilación , Unión Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/aislamiento & purificación , Proteínas Recombinantes/metabolismo

RESUMEN

BACKGROUND: The authors developed an indicator dilution technique for small animals to repeatedly determine cardiac output and blood volume without cardiac instrumentation or blood sampling. METHODS: Observations were made in the hamster (N = 32, 70 mg/kg pentobarbital) cremaster using in vivo fluorescence videomicroscopy. Fluorescein isothiocyanate-conjugated bovine serum albumin (10 mg/ml) was injected as a bolus dose (right jugular) while video recording the light intensity in a 20-microm arteriole (intensified charge-coupled device [CCD] camera at fixed gain). The intensity signal was analyzed over time (background subtracted) and calibrated to the dye concentration. The ex vivo calibration was performed using a constant optical path length (20 microm) and a range of dye and hematocrit concentrations. In vivo tube hematocrit was determined using standard methods with fluorescently labeled erythrocytes. Thus, quenching of the fluorescence signal by hemoglobin was corrected for the calibration, and the plasma space in the arteriole was determined. The steady state dye concentration measured by the light intensity at 2 min was not different from the dye concentration found by direct spectrophotometric analysis of the plasma. RESULTS: Cardiac index was calculated as milliliters of blood per minute per kilogram body weight. The calculated cardiac index was 359 +/- 18 ml.min(-1).kg(-1), which is not different from the reported values for hamsters. Cardiac output was increased twofold when enough intravenous nitroprusside or nitroglycerine was injected to decrease mean arterial pressure from 90 to 70 mmHg. Cardiac output was elevated during dobutamine infusion (16 microg.kg(-1).min(-1)) and decreased during esmolol infusion (50, 75.kg(-1).min(-1)). Blood volume determined from the steady state dye concentrations was 6.2 +/- 0.5 ml/100 g body weight, within the normal range for hamsters. CONCLUSIONS: Fluorescent dye dilution and video microscopy can be used to repeatedly determine cardiac output or blood volume in small animals.

Asunto(s)

Gasto Cardíaco , Técnicas de Dilución del Indicador , Microscopía por Video , Animales , Volumen Sanguíneo , Cricetinae , Fluoresceína-5-Isotiocianato , Colorantes Fluorescentes , Masculino , Mesocricetus

RESUMEN

Integrin-associated focal adhesion complexes provide the main adhesive links between the cellular actin cytoskeleton and the surrounding extracellular matrix. In vitro, cells utilize a complex temporal and spatially regulated mechanism of focal adhesion assembly and disassembly required for cell migration. Recent studies indicate that members of both calpain and caspase protease families can promote limited proteolytic cleavage of several components of focal adhesions leading to disassembly of these complexes. Such mechanisms that influence cell adhesion may be deregulated under pathological conditions characterized by increased cell motility, such as tumor invasion. v-Src-induced oncogenic transformation is associated with loss of focal adhesion structures and transition to a less adherent, more motile phenotype, while inactivating temperature-sensitive v-Src in serum-deprived transformed cells leads to detachment and apoptosis. In this report, we demonstrate that v-Src-induced disassembly of focal adhesions is accompanied by calpain-dependent proteolysis of focal adhesion kinase. Furthermore, inhibitors of calpain repress v-Src-induced focal adhesion disruption, loss of substrate adhesion, and cell migration. In contrast, focal adhesion loss during detachment and apoptosis induced after switching off temperature-sensitive v-Src in serum-deprived transformed cells is accompanied by caspase-mediated proteolysis of focal adhesion kinase. Thus, calpain and caspase differentially regulate focal adhesion turnover during Src-regulated cell transformation, motility, and apoptosis.

Asunto(s)

Apoptosis/fisiología , Calpaína/metabolismo , Caspasas/metabolismo , Endopeptidasas/metabolismo , Proteína Oncogénica pp60(v-src)/fisiología , Proteínas Tirosina Quinasas/metabolismo , Animales , Transformación Celular Viral , Células Cultivadas , Embrión de Pollo , Proteína-Tirosina Quinasas de Adhesión Focal , Hidrólisis , Inmunohistoquímica

RESUMEN

OBJECTIVE: Our purpose was to develop a method for adenovirus delivery to the hamster cheek pouch to experimentally target gene transfer in tissue used for microvascular studies. METHODS: Separate constructs were tested with transgenes for lacZ or green fluorescent protein (GFP) driven by three promoters: RSV, CMV, and SM22. With university approval, adenovirus was delivered in anesthetized (pentobarbital, 70 mg/kg) hamsters (n = 28) by using either a vascular systemic injection or tissue infiltration (interstitial space behind the pouch). During 3 days, animals receiving infiltration gained the expected weight, whereas those receiving vascular injection lost weight; no other behavior changes were noted. RESULTS: On day 3 postadenoviral delivery (infiltration), expression of lacZ (histology, beta-galactosidase) or GFP (fluorescence microscopy) was confirmed across the tissue (CMV and RSV promoters) and exclusively in vascular smooth muscle cells (specific SM22 promoter), without evidence of tissue inflammation. In vitro microvascular experiments verified normal responses in the cheek pouch of day 3 postadenoviral delivery animals. We tested local dilation to methacholine, adenosine, remote dilation to methacholine, adenosine, nitroprusside, and LM609 (alpha(v)beta3 integrin agonist), flow-dependent dilation, and flow recruitment. CONCLUSIONS: Thus, this method enables targeted, cell-specific gene transfer to one tissue important for microvascular studies, without significant systemic exposure and without adverse inflammation.

Asunto(s)

Adenoviridae/genética , Técnicas de Transferencia de Gen , Vectores Genéticos , Músculo Liso Vascular/metabolismo , Animales , Mejilla , Cricetinae , Genes Reporteros , Vectores Genéticos/administración & dosificación , Vectores Genéticos/farmacocinética , Vectores Genéticos/toxicidad , Proteínas Fluorescentes Verdes , Proteínas Luminiscentes/genética , Proteínas Luminiscentes/metabolismo , Proteínas Luminiscentes/farmacocinética , Masculino , Mesocricetus , Microcirculación , Regiones Promotoras Genéticas , beta-Galactosidasa/genética , beta-Galactosidasa/metabolismo , beta-Galactosidasa/farmacocinética

RESUMEN

Promastigotes of Leishmania mexicana mutants lacking the multicopy CPB cysteine proteinase genes (deltaCPB) are markedly less able than wild-type parasites to infect macrophages in vitro. deltaCPB promastigotes invade macrophages in large numbers but are unable to survive in the majority of the cells. In contrast, deltaCPB amastigotes invade and survive within macrophages in vitro. This extreme in vitro stage-specific difference was not mimicked in vivo; both promastigotes and amastigotes of deltaCPB produced lesions in BALB/c mice, but in each case the lesions grew considerably more slowly than those caused by wild-type parasites and only small lesions resulted. Inhibition of CPB in situ using cell-permeant peptidyl-diazomethylketones had no measurable effect on parasite growth or differentiation axenically in vitro. In contrast, N-benzoyloxycarbonyl-phe-ala-diazomethylketone reduced the infectivity of wild-type parasites to macrophages by 80%. Time-course experiments demonstrated that application of the inhibitor caused effects not seen with deltaCPB, suggesting that CPB may not be the prime target of this inhibitor. The data show that the CPB genes of L. mexicana encode enzymes that have important roles in intracellular survival of the parasite and more generally in its interaction with its mammalian host.

Asunto(s)

Cisteína Endopeptidasas/fisiología , Interacciones Huésped-Parásitos , Leishmania mexicana/enzimología , Animales , Líquido Ascítico/parasitología , Células Cultivadas , Inhibidores de Cisteína Proteinasa/farmacología , Diazometano/análogos & derivados , Diazometano/farmacología , Electroforesis en Gel de Poliacrilamida/veterinaria , Exudados y Transudados/parasitología , Cetonas/farmacología , Leishmania mexicana/fisiología , Ratones , Ratones Endogámicos BALB C , Transfección