RESUMO
The expression of N-myc downstream-regulated gene 1 (NDRG1) was significantly correlated with tumor angiogenesis and malignant progression together with poor prognosis in gastric cancer. However, the underlying mechanism for the role of NDRG1 in the malignant progression of gastric cancer remains unknown. Here we examined whether and how NDRG1 could modulate tumor angiogenesis by human gastric cancer cells. We established NU/Cap12 and NU/Cap32 cells overexpressing NDRG1 in NUGC-3 cells, which show lower tumor angiogenesis in vivo. Compared with parental NU/Mock3, NU/Cap12, and NU/Cap32 cells: 1) induced higher tumor angiogenesis than NU/Mock3 cells accompanied by infiltration of tumor-associated macrophages in mouse dorsal air sac assay and Matrigel plug assay; 2) showed much higher expression of CXC chemokines, MMP-1, and the potent angiogenic factor VEGF-A; 3) increased the expression of the representative inflammatory cytokine, IL-1α; 4) augmented JNK phosphorylation and nuclear expression of activator protein 1 (AP-1). Further analysis demonstrated that knockdown of AP-1 (Jun and/or Fos) resulted in down-regulation of the expression of VEGF-A, CXC chemokines, and MMP-1, and also suppressed expression of IL-1α in NDRG1-overexpressing cell lines. Treatment with IL-1 receptor antagonist (IL-1ra) resulted in down-regulation of JNK and c-Jun phosphorylation, and the expression of VEGF-A, CXC chemokines, and MMP-1 in NU/Cap12 and NU/Cap32 cells. Finally, administration of IL-1ra suppressed both tumor angiogenesis and infiltration of macrophages by NU/Cap12 in vivo. Together, activation of JNK/AP-1 thus seems to promote tumor angiogenesis in relationship to NDRG1-induced inflammatory stimuli by gastric cancer cells.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Interleucina-1alfa/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , MAP Quinase Quinase 4/metabolismo , Neovascularização Patológica/metabolismo , Neoplasias Gástricas/metabolismo , Animais , Proteínas de Ciclo Celular/genética , Linhagem Celular Tumoral , Quimiocinas CXC/genética , Quimiocinas CXC/metabolismo , Ativação Enzimática/genética , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Interleucina-1alfa/genética , Interleucina-4/genética , Interleucina-4/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/genética , MAP Quinase Quinase 4/genética , Macrófagos/metabolismo , Macrófagos/patologia , Masculino , Metaloproteinase 1 da Matriz/genética , Metaloproteinase 1 da Matriz/metabolismo , Metaloproteinase 13 da Matriz/genética , Metaloproteinase 13 da Matriz/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Neoplasias Experimentais/genética , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/patologia , Neovascularização Patológica/genética , Neovascularização Patológica/patologia , Fosforilação/genética , Neoplasias Gástricas/genética , Neoplasias Gástricas/patologia , Fator de Transcrição AP-1/genética , Fator de Transcrição AP-1/metabolismo , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
Thymidine phosphorylase (TP), an enzyme catalyzing the reversible phospholysis of thymidine, deoxyuridine and their analogs at their respective bases and 2-deoxyribose-1-phosphate, thus promoting angiogenesis, is often expressed in macrophages present in tumor stroma. In this study, we investigated whether infiltration of TP-positive macrophages as well as tumor-associated macrophages affected tumor angiogenesis. TP was expressed in human macrophage-like cells, but not in gastric cancer cells in culture. The expression level of TP, the number of infiltrating CD68+ and CD163+ macrophages, and microvessel density (MVD) in the tumor were further analyzed by immunohistochemistry in 111 patients with gastric cancer. Biostatistical analysis of digitized data obtained by image analysis showed that TP expression was significantly correlated with the number of infiltrating macrophages and MVD in intestinal type gastric cancer (p<0.05). The number of infiltrating macrophages was also correlated with MVD in both the intestinal and diffuse types (p<0.05). An increased number of CD68+ macrophages was significantly associated with poor outcome in patients with intestinal type (p<0.001), but not diffuse type cancer. TP could be a specific marker enzyme that is expressed in tumor-infiltrating macrophages, being associated with tumor angiogenesis and poor prognosis in patients with intestinal-type gastric cancer.
