RESUMO
BACKGROUND AND OBJECTIVES: Ionizing radiation (IR) is associated with thrombotic vascular occlusion predicting a poor clinical outcome. Our study examined whether IR induced tissue factor (TF) expression and procoagulability. We further investigated coordinated gene alterations associated with TF upregulation in the myelomonocytic leukemia THP-1 cells. DESIGN AND METHODS: TF expression was determined by quantitative Reverse Transcriptase (TaqMan) PCR, TF ELISA and TF activity by a two stage chromogenic assay in the time course of days 1, 3, 7, 10, and 17 post IR. To detect IR-induced alterations in gene expression, Affymetrix HG U133 Plus 2.0 microarrays were used. RESULTS IR induced a significant increase in TF/GAPDH mRNA ratios and cellular TF protein on days 3 and 7 post IR (20 Gy [p>or=0.01] and 40 Gy [p
Assuntos
Fatores de Coagulação Sanguínea/biossíntese , Regulação Leucêmica da Expressão Gênica/efeitos da radiação , Leucemia Mielomonocítica Aguda/patologia , Proteínas de Neoplasias/biossíntese , Trombofilia/etiologia , Tromboplastina/biossíntese , Apoptose/genética , Apoptose/efeitos da radiação , Fatores de Coagulação Sanguínea/genética , Fatores de Coagulação Sanguínea/efeitos da radiação , Linhagem Celular Tumoral/metabolismo , Linhagem Celular Tumoral/efeitos da radiação , Ensaio de Imunoadsorção Enzimática , Fator Xa/biossíntese , Perfilação da Expressão Gênica , Humanos , Inflamação , Leucemia Mielomonocítica Aguda/sangue , Leucemia Mielomonocítica Aguda/complicações , NF-kappa B/antagonistas & inibidores , NF-kappa B/metabolismo , Proteínas de Neoplasias/antagonistas & inibidores , Proteínas de Neoplasias/genética , Nitrilas/farmacologia , Análise de Sequência com Séries de Oligonucleotídeos , Aceleradores de Partículas , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , RNA Neoplásico/biossíntese , RNA Neoplásico/genética , Radiação Ionizante , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sulfonas/farmacologia , Tromboplastina/genéticaRESUMO
INTRODUCTION: The therapeutic application of ionizing radiation is associated with thrombotic events, but the exact underlying molecular mechanisms are still unclear. Tissue factor (TF), the primary initiator of blood coagulation, is essentially involved in the pathophysiology of thrombosis. Circulating monocytes have been identified to upregulate TF under inflammatory conditions and, thereby, enhance blood thrombogenicity. The study examines the effect of irradiation on the cellular procoagulability and TF protein expression of human peripheral blood mononuclear cells (PBMNCs) in a time period of 7 days. MATERIALS AND METHODS: Human PBMNCs were irradiated with 20 Gy. Procoagulability of PBMNCs, released microparticles and microparticle-free cell supernatant was analyzed by a chromogenic assay and TF protein expression quantified by TF ELISA. To determine whether irradiated PBMNCs and shed microparticles initiate plasma clotting, a one stage clotting assay was performed. RESULTS: We found a significant increase of PBMNC-associated procoagulant activity over a time period of 7 days post irradiation. Moreover, 3 days post irradiation PBMNCs initiated the plasma clotting faster than non-irradiated cells. An enhanced cellular TF protein concentration was persistently observed throughout the investigated time up to 7 days post irradiation. Microparticle-associated TF activity significantly increased 3 days post irradiation compared with the non-irradiated controls. PBMNC-derived microparticles post irradiation also initiated the plasma clotting faster than microparticles derived from controls. CONCLUSIONS: The results show irradiation to induce TF expression and to increase procoagulability of PBMNCs and cell-derived microparticles. This could be a possible mechanism by which ionizing radiation enhances blood thrombogenicity.
