RESUMEN
Filamin A (FLNa) is a ubiquitously expressed cytoplasmic protein, which composes of an N-terminal actin binding domain (ABD) followed by 24 Ig-like repeats. FLNa functions as a cytoskeletal protein that links transmembrane receptors, including integrins, to F-actin and serves as a signaling intermediate. Recent studies have identified FLNa as a scaffold protein that interacts with over 90 proteins and plays vital roles in cellular signaling transduction. Mutations or defects in human FLNa gene have been shown to cause numerous developmental defects. Moreover, aberrant expression of FLNa has been observed in many cancers, such as parathyroid tumor, cervical cancer, and breast cancer. However, its role in lung adenocarcinoma has seldom been discussed. In the present study, our in vitro and in vivo studies demonstrated that silencing FLNa expression in lung cancer cell line A549 cells promoted proliferation, migration, and invasiveness of A549 cells by enhancing the activation of epidermal growth factor receptor and ERK signaling pathway. These results shed light on novel functions of FLNa in lung cancer and uncovered novel mechanisms, these results provided possible targets for the prediction and treatment for lung adenocarcinoma.
Asunto(s)
Proliferación Celular/genética , Receptores ErbB/genética , Filaminas/genética , Regulación Neoplásica de la Expresión Génica , Interferencia de ARN , Células A549 , Adenocarcinoma/genética , Adenocarcinoma/metabolismo , Adenocarcinoma/patología , Movimiento Celular/genética , Receptores ErbB/metabolismo , Filaminas/metabolismo , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patología , Sistema de Señalización de MAP Quinasas/genética , Metástasis de la NeoplasiaRESUMEN
Both tumor suppressor and tumor promoter roles, which are dependent on the tumor type, have been described for caveolin-1 (CAV-1). Because CAV-1 can modulate cell signaling, we tested the hypothesis that it regulates lung adenocarcinoma cell proliferation and metastasis via modulation of epidermal growth factor receptor (EGFR) activity. The lung adenocarcinoma cell line, GLC-82, was transfected with pcDNA3.1CAV-1 plasmid, before cell proliferation, migration, and invasion were analyzed. In the in vivo xenograft model, the relationship between the CAV-1 expression and EGFR phosphorylation and signaling was assessed by western blot analysis. The relationship between the CAV-1 as well as Ki67 expression and the clinicopathological characteristics of 68 lung adenocarcinoma patients was also examined using immunohistochemistry. Overexpression of CAV-1 significantly increased GLC-82 proliferation (p < 0.001), migration (p < 0.001), and invasion (p = 0.002) as well as EGFR and ERK phosphorylation (p < 0.05). The GLC-82/CAV-1 cell tumors were also significantly larger than those of control cells (all p ≤ 0.05). In lung adenocarcinoma patients, CAV-1 expression was positively correlated with lymph node metastasis and cancer stage. Finally, CAV-1 expression was associated with the expression of Ki-67, a marker of cell proliferation. CAV-1 enhanced GLC-82 cell proliferation, migration, and invasion possibly through EGFR and ERK signaling. Furthermore, the relationship of CAV-1 with Ki67 expression, a marker of proliferative capacity, in lung adenocarcinoma samples is suggestive of its role in disease progression. Further studies are required to confirm the role of CAV-1 in the metastasis of lung adenocarcinoma as well as its potential prognostic and therapeutic value.
Asunto(s)
Adenocarcinoma/genética , Caveolina 1/genética , Movimiento Celular/genética , Proliferación Celular/genética , Regulación Neoplásica de la Expresión Génica/genética , Neoplasias Pulmonares/genética , Invasividad Neoplásica/genética , Adenocarcinoma/patología , Adenocarcinoma del Pulmón , Animales , Línea Celular Tumoral , Receptores ErbB/genética , Femenino , Humanos , Antígeno Ki-67/genética , Neoplasias Pulmonares/patología , Metástasis Linfática/genética , Metástasis Linfática/patología , Sistema de Señalización de MAP Quinasas/genética , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Persona de Mediana Edad , Invasividad Neoplásica/patología , Fosforilación/genética , Pronóstico , Transducción de Señal/genéticaRESUMEN
PURPOSE: Filamin A (FLNa) cross-links actin filaments into dynamic orthogonal networks and interacts with binding proteins of diverse cellular functions that are implicated in cell growth and motility regulation. Here, we tested the hypothesis that FLNa plays a role in cancer proliferation and metastasis via the regulation of epidermal growth factor receptor (EGFR) function. METHODS: Ectopic expression and knockdown of FLNa in human melanoma cell lines was performed to investigate changes in cellular proliferation, migration and invasion in vitro and tumor growth in a xenograft model in the mouse. The role of FLNa in EGFR expression and signaling was evaluated by Western blot. Immunohistochemistry was performed on histological sections of human melanoma tumors to determine whether an association existed between FLNa and overall survival. RESULTS: The depletion of FLNa significantly reduced the proliferation, migration and invasion of two melanoma cell lines in vitro and was associated with smaller tumors in a xenograft model in vivo. EGF-induced phosphorylation of EGFR and activation of the Raf-MEK-ERK cascade was negatively affected by the silencing of FLNa both in vitro and in vivo. Cancer patients with low melanoma tumor FLNa expression have improved survival benefit. CONCLUSION: These data indicate that enhanced tumorigenesis occurs through increase in EGF-induced EGFR activation in FLNa-expressing melanoma cells and that high FLNa levels are predictors of negative outcome for patients with melanoma tumors.