RESUMO
Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is a member of the tumor necrosis factor superfamily of structurally related cytokines. TWEAK acts on responsive cells via binding to a cell surface receptor named Fn14. Recent studies have demonstrated that TWEAK can stimulate numerous cellular responses including cell proliferation, migration, and proinflammatory molecule production. It has also been reported that TWEAK can stimulate blood vessel formation in the rat cornea angiogenesis assay, but it is presently unknown whether this cytokine could play a role in the pathological angiogenesis associated with human diseases such as cancer, rheumatoid arthritis, and diabetic retinopathy. In the present study we investigated whether TWEAK was expressed in human tumors and whether it could promote tumor growth and angiogenesis in vivo. TWEAK mRNA expression was detected in many tumor types by cDNA array hybridization analysis, and TWEAK protein expression was confirmed in human colon cancer tissue by immunohistochemistry. As an initial approach to address whether TWEAK might act as a tumor angiogenesis factor, we established several human embryonic kidney cell lines that constitutively secrete a soluble TWEAK protein and examined their growth properties in vitro and in vivo. We found that although TWEAK-overexpressing cells do not have a growth advantage in vitro, they form larger and more highly vascularized tumors in athymic mice when compared with control, vector-transfected cells. This result suggests that the TWEAK-Fn14 signaling system may be a potential regulator of human tumorigenesis.
Assuntos
Proteínas de Transporte/fisiologia , Neoplasias Experimentais/irrigação sanguínea , Neoplasias Experimentais/patologia , Animais , Proteínas Reguladoras de Apoptose , Proteínas de Transporte/biossíntese , Proteínas de Transporte/genética , Processos de Crescimento Celular/fisiologia , Linhagem Celular , Citocina TWEAK , Feminino , Expressão Gênica , Humanos , Camundongos , Camundongos Nus , Transplante de Neoplasias , Neoplasias Experimentais/genética , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Transfecção , Transplante Heterólogo , Fatores de Necrose TumoralRESUMO
Glioblastoma multiforme comprises the majority of human brain tumors. Patients with glioblastoma multiforme have poor survival rates, with an average life expectancy of <1 year. To assess possible mechanisms and to potentially target invasive glioma cells, we previously measured the gene expression profiles of glioma cells under migration-activated or passive states. One of the genes identified was Fn14, which encodes a cell surface receptor for the tumor necrosis factor superfamily member named TWEAK. In this study, we show that Fn14 gene expression is induced in migration-activated glioma cells in vitro and significantly increases according to tumor grade in vivo (P < 0.01), with highest levels in glioblastoma tissue specimens. The in situ expression pattern of Fn14 mRNA and protein was confined to primary glioma cells and the vascular endothelium, with no detection in adjacent normal brain. Conversely, TWEAK mRNA levels are low in glioblastoma samples relative to normal brain tissue. In addition, activation of the Fn14 receptor by addition of recombinant TWEAK resulted in increased glioma cell migration in vitro. These results suggest a positive role for TWEAK and Fn14 in glioma progression and indicate that Fn14 gene expression may serve as a marker for invasive glioma cells.
Assuntos
Neoplasias Encefálicas/patologia , Proteínas de Transporte/genética , Glioma/patologia , Regulação para Cima , Proteínas Reguladoras de Apoptose , Astrocitoma , Neoplasias Encefálicas/genética , Movimento Celular , Sobrevivência Celular , Citocina TWEAK , Endotélio Vascular/metabolismo , Glioblastoma/genética , Glioblastoma/patologia , Glioma/genética , Humanos , Hibridização In Situ , Invasividade Neoplásica , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transcrição Gênica , Células Tumorais Cultivadas , Fatores de Necrose TumoralRESUMO
OBJECTIVE: TWEAK, a member of the tumor necrosis factor superfamily, binds to the Fn14 receptor and stimulates angiogenesis in vivo. In this study, we investigated Fn14 gene expression in human endothelial cells (ECs) and examined the effect of TWEAK, added either alone or in combination with fibroblast growth factor-2 (FGF-2) or vascular endothelial growth factor-A (VEGF-A), on EC proliferation, migration, and survival in vitro. We also determined whether a soluble Fn14-Fc fusion protein could inhibit TWEAK biologic activity on ECs and investigated TWEAK signal transduction in ECs. METHODS AND RESULTS: We found that both FGF-2 and VEGF-A could induce Fn14 mRNA expression in ECs. TWEAK was a mitogen for ECs, and this proliferative activity could be inhibited by an Fn14-Fc decoy receptor. Furthermore, TWEAK treatment activated several intracellular signaling pathways in ECs and potentiated FGF-2--and VEGF-A--stimulated EC proliferation. TWEAK also had EC chemotactic activity, but it did not promote EC survival. CONCLUSIONS: These results indicate that TWEAK is an EC growth and migration factor but not a survival factor. TWEAK can also enhance both FGF-2 and VEGF-A mitogenic activity on ECs. Thus, TWEAK may act alone as well as in combination with FGF-2 or VEGF-A to regulate pathological angiogenesis.