RESUMEN
Neural cell adhesion molecule (NCAM) is involved in cell growth, migration, and differentiation. Its expression and/or polysialylation appear to be deregulated in many different cancer types. We employed the lung tumor cell line LP07, syngeneic in BALB/c mice to investigate the role of NCAM in malignant progression. LP07 cells express the three main NCAM isoforms, all of them polysialylated. This cells line, pretreated with an anti-NCAM antibody and inoculated intravenously (i.v.) into syngeneic mice, developed less and smaller lung metastases. In vitro studies showed that NCAM bound antibody inhibited cell growth, mainly due to an increase in apoptosis, associated with a decrease of cyclin D1 and enhanced expression of active caspase 3 and caspase 9. Anti-NCAM-treated LP07 cells showed impairment in their ability to migrate and adhere to several extracellular matrix components. Secreted uPA activity was also reduced. NCAM-140 knocked-down by siRNA in LP07 cells pretreated or not with anti-NCAM showed an impaired metastasizing ability upon i.v. inoculation into mice. These results suggest that anti-NCAM treatment could be mimicking homophilic trans-interactions and NCAM-140 knocked-down impairs heterophilic interactions, both leading to inhibition of metastatic dissemination. The involvement of NCAM in lung tumor progression was confirmed in human NSCLC tumors. Sixty percent of the cases expressed NCAM at tumor cell level. A multivariate analysis indicated that NCAM expression was associated with a shorter overall survival in this homogeneous series of Stages I and II NSCLC patients. NCAM may be able to modulate mechanisms involved in lung carcinoma progression and represents an attractive target to control metastatic progression.
Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas/metabolismo , Modelos Animales de Enfermedad , Neoplasias Pulmonares/metabolismo , Moléculas de Adhesión de Célula Nerviosa/metabolismo , Animales , Carcinoma de Pulmón de Células no Pequeñas/genética , Carcinoma de Pulmón de Células no Pequeñas/inmunología , Adhesión Celular/genética , Adhesión Celular/inmunología , Línea Celular Tumoral , Movimiento Celular/genética , Movimiento Celular/inmunología , Proliferación Celular , Regulación hacia Abajo , Humanos , Inmunohistoquímica , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/inmunología , Ratones , Ratones Endogámicos BALB C , Metástasis de la Neoplasia/fisiopatología , Isoformas de Proteínas/genética , Isoformas de Proteínas/inmunología , Isoformas de Proteínas/metabolismo , ARN Interferente Pequeño/metabolismoRESUMEN
In this paper we investigated whether protein kinase C (PKC) beta1 and PKCepsilon, members of the classical and novel PKC family, respectively, induce phenotypic alterations that could be associated with tumor progression and metastatic dissemination in a murine model of breast cancer. Stable overexpression of PKCbeta1 in LM3 cells altered their ability to proliferate, adhere, and survive, and impaired their tumorigenicity and metastatic capacity. Moreover, PKCbeta1 induced the re-expression of fibronectin, an extracellular matrix glycoprotein which loss has been associated with the acquisition of a transformed phenotype in different cell models, and exerted an important inhibition on proteases production, effects that probably impact on LM3 invasiveness and dissemination. Conversely, PKCepsilon overexpression enhanced LM3 survival, anchorage-independent growth, and caused a significant increase in spontaneous lung metastasis. Our results suggest PKCbeta1 functions as an inhibitory protein for tumor growth and metastasis dissemination whereas PKCepsilon drives metastatic dissemination without affecting primary tumor growth.
Asunto(s)
Neoplasias Mamarias Experimentales/enzimología , Invasividad Neoplásica/patología , Proteína Quinasa C-epsilon/metabolismo , Proteína Quinasa C/metabolismo , Animales , Western Blotting , Adhesión Celular/fisiología , Línea Celular Tumoral , Proliferación Celular , Modelos Animales de Enfermedad , Femenino , Técnica del Anticuerpo Fluorescente , Neoplasias Mamarias Experimentales/genética , Neoplasias Mamarias Experimentales/patología , Ratones , Ratones Endogámicos BALB C , Invasividad Neoplásica/genética , Proteína Quinasa C/genética , Proteína Quinasa C beta , Proteína Quinasa C-epsilon/genética , TransfecciónRESUMEN
Protein kinase C (PKC) delta, a member of the novel family of PKC serine-threonine kinases, has been implicated in negative regulation of proliferation and apoptosis in a large number of cell types, including breast cancer cell lines, and postulated as a tumor suppressor gene. In this study we show that in murine NMuMG mammary cells PKCdelta promotes a mitogenic response. Overexpression of PKCdelta in NMuMG cells leads to a significant increase in [3H]-tymidine incorporation and cell proliferation, as well as enhanced extracellular signal-regulated kinase (ERK)-mitogen-activated protein kinase (MAPK) activation. Activation of PKCdelta with a phorbol ester leads to elevated cyclin D1 expression and an hyperphosphorylated Rb state. Surprisingly, ectopic expression of PKCdelta conferred anchorage-independent growth capacity to NMuMG cells. PKCdelta overexpressors showed enhanced resistance to apoptotic stimuli, such as serum deprivation or doxorubicin treatment, an effect that correlates with hyperactivation of the Akt survival pathway. Our results provide evidence for a role of PKCdelta as a positive modulator of proliferative and survival signals in immortalized mammary cells. The fact that PKCdelta exerts differential responses depending on the cell context not only highlights the necessity to carefully understand the signaling events controlled by this PKC in each cell type but also suggests that we should be cautious in considering this kinase a target for cancer therapy.