Estudo imuno-histoquímico e in vitro de proteínas do sistema ativador de plasminogênio em carcinomas de células escamosas de língua oral / Immunohistochemical and in vitro study of plasminogen activator system proteins in oral tongue squamous cell carcinomas

O carcinoma de células escamosas (CCE) é a neoplasia maligna mais frequente da cavidade oral e apresenta prognóstico desfavorável. Assim sendo, pesquisas têm buscado esclarecer o papel de biomarcadores no comportamento biológico do CCE oral. Nesta perspectiva, destacam-se o ativador de plasminogênio tipo uroquinase (uPA) e seu receptor (uPAR), além do inibidor do ativador de plasminogênio-1 (PAI-1). O presente trabalho analisou, por meio de imuno-histoquímica, a expressão das proteínas uPA, uPAR e PAI-1 no CCE de língua oral (CCELO) e sua relação com parâmetros clinicopatológicos. Este experimento também avaliou os efeitos in vitro da proteína recombinante humana PAI-1 (rhPAI-1) na linhagem celular SCC25, derivada de CCELO. A imunoexpressão de uPA, uPAR e PAI-1 foi analisada em 60 casos de CCELO, de forma semiquantitativa, nas células neoplásicas do front de invasão tumoral. Visando a associação dos achados imuno-histoquímicos com variáveis clinicopatológicas e taxas de sobrevida, os casos foram classificados nas categorias baixa expressão (≤50% das células positivas) e alta expressão (>50% das células positivas). No experimento in vitro, foram analisados os seguintes grupos: G0 (controle; células cultivadas na ausência de rhPAI-1), G10 (células tratadas com rhPAI-1 a 10 nM) e G20 (células tratadas com rhPAI-1 a 20 nM). Diferenças entre estes grupos foram investigadas através dos ensaios: viabilidade celular (Alamar Blue), ciclo celular (marcação com iodeto de propídio, PI), apoptose/necrose (marcação com Anexina V e PI), atividade migratória (Wound healing) e invasão celular (Transwell). A análise imuno-histoquímica revelou alta expressão do uPA na maioria dos CCELOs, mas sem relações significativas com parâmetros clinicopatológicos. As expressões do uPAR e do PAI-1, em nível membranar, foram associadas a recidivas locais (p=0,019) e ao elevado tumor budding (p=0,046), respectivamente. A expressão membranar do PAI-1 também apresentou associação significativa com o alto escore de risco histopatológico (p=0,043). A análise estatística evidenciou ausência de associações significativas entre as variáveis imunohistoquímicas (uPA, uPAR e PAI-1) e indicadores de prognóstico do CCELO (sobrevida específica e sobrevida livre da doença). No estudo in vitro, decorridas 24 horas da administração da rhPAI-1, os grupos G10 e G20 exibiram maior viabilidade celular em comparação ao grupo controle (p=0,020), assim como aumento da progressão para a fase S do ciclo celular (p=0,024). No que concerne aos percentuais de células apoptóticas e necróticas, não foram encontradas diferenças significativas entre os grupos. Nos grupos celulares cultivados na presença da rhPAI1, também foi constatado aumento da atividade migratória (p=0,039) e do potencial de invasão (p=0,039), respectivamente, nos intervalos de 24 horas e 72 horas. Os achados deste estudo sugerem o envolvimento das proteínas uPA, uPAR e PAI-1 na patogênese do CCELO. Entretanto, a expressão destes biomarcadores pode não estar relacionada com a sobrevida dos pacientes. Os resultados in vitro demonstram que o PAI-1 exerce efeitos estimulatórios na proliferação, migração e invasão celular, podendo assim contribuir para a agressividade biológica do CCELO (AU).

Squamous cell carcinoma (SCC) is the most frequent malignant neoplasm of the oral cavity and has an unfavorable prognosis. Thus, studies have sought to clarify the role of biomarkers in the biological behavior of oral SCC. Within this context, urokinase-type plasminogen activator (uPA) and its receptor (uPAR), as well as plasminogen activator inhibitor 1 (PAI-1), are particularly interesting. The present study analyzed, by means of immunohistochemistry, the expressions of uPA, uPAR and PAI-1 in oral tongue SCC (OTSCC) and their relationship with clinicopathological parameters. This experiment also evaluated the in vitro effects of recombinant human PAI-1 (rhPAI-1) on the OTSCC-derived cell line SCC-25. The immunoexpression of uPA, uPAR and PAI-1 was analyzed semiquantitatively in neoplastic cells of the invasion front of 60 OTSCC cases. Aiming to determine the association between immunohistochemical findings, clinicopathological variables and survival rates, the cases were classified as low expression (≤50% of positive cells) and high expression (>50% of positive cells). The following groups were analyzed in the in vitro experiment: G0 (control; cells cultured in the absence of rhPAI-1), G10 (cells treated with 10 nM rhPAI-1), and G20 (cells treated with 20 nM rhPAI-1). Differences between these groups were investigated using the following assays: cell viability (Alamar Blue), cell cycle (staining with propidium iodide, PI), apoptosis/necrosis (staining with Annexin V and PI), migratory activity (Wound healing), and cell invasion (Transwell). Immunohistochemical analysis revealed high expression of uPA in most OTSCC cases, but there were no significant associations with clinicopathological parameters. The high membrane expression of uPAR and PAI-1 was associated with local recurrence (p=0.019) and high tumor budding (p=0.046), respectively. Membrane expression of PAI-1 also presented a significant association with high-risk cases (p=0,043). Statistical analysis demonstrated no significant associations between the immunohistochemical variables (uPA, uPAR and PAI-1) and prognostic indicators of OTSCC (disease-specific and disease-free survival). In the in vitro experiment, 24 hours after administration of rhPAI-1, G10 and G20 exhibited greater cell viability compared to the control group (p=0.02), as well as increased progression to the S phase of the cell cycle (p=0.024). There were no significant differences in the percentages of apoptotic or necrotic cells between groups. In the groups cultured in the presence of rhPAI-1, migratory activity (p=0.039) and invasion potential (p=0.039) were found to be increased after 24 and 72 hours, respectively. The findings of this study suggest the involvement of uPA, uPAR and PAI-1 in the pathogenesis of OTSCC. Nevertheless, the expression of these biomarkers may not be related to survival of patients. The in vitro results suggest that PAI-1 exerts stimulatory effects on cell proliferation, migration and invasion and may therefore contribute to the biological aggressiveness of OTSCC (AU).

Influence of homocysteine on fibrin network lysis.

To elucidate some of the links between homocysteine and vascular disease, we have evaluated the effect of the amino acid on the formation (by kinetics studies), structure (by electron microscopy) and lysis of the fibrin network, using tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA). We have studied whether homocysteine could alter the activity of the components involved in fibrinolysis (by amidolytic and thrombolytic methods). The results showed that homocysteine-associated networks were more compact and branched than controls (52 +/- 6 vs 44 +/- 5 fibers/field, P = 0.008), and were formed by shorter and thicker fibers. This clot proved to be more resistant to fibrinolysis with u-PA than control [lysis time 50%: 257 +/- 16 (homocysteine) vs 187 +/- 6 min (control); P < 0.004], but there were no differences with t-PA. Homocysteine did not affect the biological activities of plasmin, or plasminogen activation by t-PA and u-PA. Defective fibrinolysis with u-PA was therefore associated with homocysteine-fibrin structural alterations rather than the homocysteine effect on the biological activities of the fibrinolytic components evaluated. Results suggest that hyperhomocysteinemic patients could produce tight clots, were more resistant to lysis, and generated a procoagulant environment in situ. We believe that our findings may contribute to understanding the mechanisms involved in the homocysteine harmful effect.

Parâmetros hemostáticos na gravidez normal e após o parto / Hemostatic parameters in normal pregnancy and postpartum

Relatos da literatura revelam que a gravidez normal está associada a complexas alterações da hemostasia que resultam em um estado de hipercoagulabilidade sanguínea. O objetivo do presente estudo foi estabelecer a evolução de 8 marcadores que refletem diversas etapas do processo hemostático, avaliados ao final da gravidez e 4 meses após o parto. A condição hemostática de 8 gestantes que não tiveram complicações durante a gravidez e não apresentavam doenças intercorrentes no 3º trimestre de gestação (Grupo I) e 4 meses após o parto (Grupo II) foi avaliada através da determinação dos níveis plasmáticos de trombomodulina (TM), ativador tissular do plasminogênio (t-PA), inibidor do ativador do plasminogênio (PAI), fragmento 1 + 2 da protrombina (F¹+²), plasminogênio (Plg), fibrinogênio, Dímero D (D-Di) e da contagem de plaquetas. A análise dos resultados mostrou uma diferença significativa entre as médias obtidas nos dois grupos para TM (p<0,05), t-PA (p<0,01), PAI-1 (p<0,05), fibrinogênio (p<0,01),F ¹+² (p<0,001) e D-Di (p< 0,001). Para plasminogênio e contagem de plaquetas nenhuma diferença foi observada. Estes resultados permitem concluir que a gravidez normal está associada a uma exacerbação do mecanismo da coagulação e que o sistema fibrinolítico está funcionando adequadamente, o que previne a formação de trombos. Quatro meses após o parto, nenhuma alteração nos parâmetros hemostáticos avaliados foi observada, caracterizando o retorno à condição hemostática normal.

Evaluación retrospectiva del uso de activador tisular del plasminógeno (rt-PA) en el manejo del infarto agudo de miocardio en el servicio de urgencias de la Clínica Shaio

Objetivo: Evaluar el uso de activador tisular del plasminógeno recombinante (rt-PA) en los pacientes con IAM que ingresaron por el servicio de urgencias. Materiales y métodos: Estudio descriptivo retrospectivo de corte transversal en donde se tomaron todos los pacientes con diagnóstico de IAM al ingreso en urgencias durante el período comprendido entre enero de 1996 hasta julio de 1997 en los cuales se utilizó la terapia trombolítica con rt-PA. Se administró el esquema acelerado de rt-PA seguido por infusión de heparina para mantener PTT entre 50 y 70 segundos por 24 a 48 horas. Las indicaciones para administrar rt-PA fueron: edad menor de 75 años, infarto de localización anterior y tiempo de evolución menor de 6 horas. La recolección de la información se realizó a partir de la historia clínica. Las variables estudiadas fueron edad, sexo, tipo de infarto, localización, clasificación de killip, tiempo de evolución al momento de la consulta, uso, tipo y causa de exclusión de trombosis con rt-AP. permeabilidad de la arteria relacionada con el infarto, realización de angioplastia, requerimiento de cirugía (electiva o de urgencia), complicaciones y mortalidad antes de la intervención con angioplastia electiva o cirugía. Resultados: De un total de 458 pacientes con diagnóstico de IAM se realizó terapia de recanalización en 206 pacientes (44.5 por ciento), 12 con angioplastia primaria (6 por ciento), 146 (70.5 por ciento) con STK y 48 (23.5 por ciento) con rt-PA. De estos pacientes 42 (87.5 por ciento) fueron hombres y 6 (12.5 por ciento) mujeres. Las edades estuvieron entre 42 años el más joven y 75 años el de mayor edad, con un promedio de 60-17 años. El tiempo promedio de consulta a urgencias después del inicio de los síntomas fue de 4.9 horas. Ningún paciente entró con Killip IV, 3 (6.5 por ciento) Killip I, 14 (29 por ciento) en Killip II yb 31 (64.5 por ciento) en Killip III. La principal causa de exclusión de trombólisis con rt-PA fue la consulta fuera de tiempo > 6 horas. Se presentó un caso de hemorragia de vías digestivas clasificada como menor ya que no requirió transfusión. De las complicaciones secundarias al IAM se presentó choque en 4 (8.3 por ciento), arritmia ventricular en 3 (6.2 por ciento); pericarditis en 2 (4.15 por ciento); angina post IAM en 1 (2.5 por ciento); insuficiencia mitral en 1 (2.5 por ciento); trombo intracavitario 1 (2.5 por ciento). La mortalidad entre los pacientes trombolizados...

Terapêutica de reposiçäo hormonal / Hormone replacement therapy

A mulher, no período pré-menopausa, está relativamente protegida de doença cardiovascular. Admite-se que essa proteção seja devida ao estrogênio e a seus efeitos sobre fatores de risco e mecanismos de aterogênese. A terapêutica de reposição hormonal, definida como tratamento com estrogênio ou a combinação estrogênio e protestógeno, representa, hoje, tema de permanente debate, considerando que sua indicação pode modificar o impacto de várias doenças que afetam a mulher na menopausa. A terapêutica de reposição pode reduzir o risco de osteoporose, câncer de cólon, doença de Alzheimer e doença isquêmica miocárdica, e, simultaneamente, aumentar a mortalidade devida a câncer de mama e de endométrio. Até que estejam disponíveis os resultados de ensaios clínicos aleatórios, com "endpoints" adequadamente definidos de doença cardiovascular, a decisão para o uso de reposição hormonal deverá ser individualizada, levando em conta os possíveis benefícios em mulheres de alto risco cardiovascular frente aos riscos de câncer de endométrio e câncer de mama.

Temporal pattern of plasminogen activator activity in the developing chick cerebellum.

Plasminogen activators are considered to be involved in several developmental events. The present work aims at characterizing the developmental pattern of expression of plasminogen activators in the chick cerebellum. Soluble fractions derived by ultracentrifugation from Triton X-100 treated membrane fractions were used for determination of the enzyme activity with a radial fibrinolytic assay. By using specific inhibitors and different anti-plasminogen activators antibodies it is shown that only one type of the enzyme, the urokinase-type plasminogen activator, is expressed during the cerebellum ontogeny. Our results show the existence of a bimodal pattern of enzyme activity with two peaks that temporally coincide with the processes of massive neuronal migration, neurite outgrowth and synapse formation and plasticity. It is proposed that plasminogen activator could play a role in these developmental events and that its pattern of variability is developmentally regulated.

Epidemiología de los estados trombofílicos / Epidemiology of the thrombophilic states

Esta revisión hace referencia a la epidemiología de los estados trombofílicos más importantes, con todas las dificultades para establecer su verdadera prevalencia, la cual se halla influenciada por diversos factores: demográficos, diagnósticos, poblacionales, entre otros. De los pacientes con antecedentes trombóticos recurrentes y/o historia familiar, sólo un 10 por ciento obedece a una trombofilia, existiendo alrededor de un 25 por ciento que posiblemente la presente, pero en donde su etiología no ha podido ser determinada con los métodos hoy disponibles. Las alteraciones fibrinolíticas continúan siendo objeto de discusión, con respecto a la relevancia clínica y a su carácter hereditario

Epidemiología de los estados trombofílicos / Epidemiology of the thrombophilic states

Esta revisión hace referencia a la epidemiología de los estados trombofílicos más importantes, con todas las dificultades para establecer su verdadera prevalencia, la cual se halla influenciada por diversos factores: demográficos, diagnósticos, poblacionales, entre otros. De los pacientes con antecedentes trombóticos recurrentes y/o historia familiar, sólo un 10 por ciento obedece a una trombofilia, existiendo alrededor de un 25 por ciento que posiblemente la presente, pero en donde su etiología no ha podido ser determinada con los métodos hoy disponibles. Las alteraciones fibrinolíticas continúan siendo objeto de discusión, con respecto a la relevancia clínica y a su carácter hereditario (AU)

¿Por qué pacientes jóvenes presentan infarto de miocardio?: Búsqueda de estados protrombóticos, un aporte al futuro / Why do young patients suffer myocardial infarction?: Search of prothrombotic states, a contribution to the future

Se presenta una serie de casos de 26 pacientes jóvenes (los de sexo masculino menores de 45 años y las de sexo femenino menores de 55 años) que habían presentado infarto de miocardio, los cuales fueron estudiados para pesquisar si eran portadores de estados protrombóticos dosificándose antitrombina III (AT III), proteína c, proteína S e inhibidores de los activadores de plasminógeno (PAI) así como su eventual relación con la presencia de aterosclerosis coronaria. Fueron hallados 12 pacientes, portadores de estados protrombóticos: 6 con exceso de PAI, 3 con déficit de Proteína C, 2 con déficit de Proteína S y 1 con déficit de Antitrombina III. De estos pacientes 9 tenían coronariopatía en la cineangiocoronariografía, 2 tenían coronarias normales y un paciente no fue estudiado. Si bien por las características del trabajo no puede conocerse la incidencia de estas anomalías, por el elevado número de pacientes hallados positivos aún en presencia de coronariopatía, se sugiere el estudio de pacientes similares a la población estudiada y eventual tratamiento anticoagulante hasta que trabajos prospectivos delimiten con mayor precisión este problema (AU)

Plasminogen activation and breast cancer

Plasminogen activation is a widespread cellular mechanism for localized extracellular proteolysis that is postulated to participate in many diverse physiological and pathological phenomena. The present review in intended as an introduction to the subject, and is by no means comprehensive, except for the section on breast cancer. Seral extensive reviews are available that should be consulted by intersted readers (1-6).

Impairment of fibrinolysis during the growth of two murine mammary adenocarcinomas.

The fibrinolytic activity present in the euglobulin (EU) fraction of BALB/c mice before and during the growth of M3 and MM3 murine mammary adenocarcinomas was characterized. The main plasminogen activator (PA) form contained in EUs from control mice was defined as murine urokinase-type PA (uPA). Overall fibrinolytic activity decreased significantly during tumor development. Zymographies showed that this fall was associated with a reduction in the free uPA band (47 kDa) and to the detection of a tissue-type PA (tPA) complexed band (117 kDa). Western blotting showed free tPA protein (68 kDa) in control mice, that disappeared in M3 tumor-bearing mice. In this model, high subcutaneous tumor burden induces a severe impairment in the circulating fibrinolytic system.

Plasminogen activator and its inhibitor in cancer patients treated with tumor necrosis factor.

BACKGROUND: We noted the presence of plasma fibrin degradation products in patients treated with recombinant human tumor necrosis factor (TNF) in a phase I trial. PURPOSE: To further define this observation, we investigated the effects of TNF on the fibrinolytic system in patients entered in the same trial. METHODS: In the 14 patients studied, fibrinolytic parameters were measured by analyzing blood samples for tissue plasminogen activator and inhibitor at 0, 1, 2, 4, 6, and 18-24 hours after initiation of TNF treatment. We used a chromogenic substrate method to determine activity of plasminogen activator and its inhibitor and an enzyme-linked immunosorbent assay (ELISA) to determine levels of antigen (tissue-type plasminogen activator). Molecular weight was determined by zymographic assay. RESULTS: TNF treatment was associated with tissue-type plasminogen activator induction within 1 hour of TNF initiation. The plasminogen activator produced was consistent with tissue-type plasminogen activator derived from endothelium as evidenced by molecular weight analysis and ELISA. Moreover, induction of plasminogen activator inhibitor occurred following the release of tissue-type plasminogen activator, and our data suggest a dose-response effect for TNF. At high doses (i.e., 200 and 240 micrograms/m2), there was a more rapid and prolonged release of plasminogen activator inhibitor, which had an inverse relationship with the level of antigenic tissue-type plasminogen activator. Zymographic analysis showed urokinase-type plasminogen activator activity in 13 of 14 patients. In three patients, simultaneous measurements of white blood cells and tissue-type plasminogen activator revealed a temporal association between the TNF-associated rapid granulocytopenia at 30 minutes after TNF initiation and release of tissue-type plasminogen activator antigen. CONCLUSIONS: The results suggest a positive association between TNF and rapid induction of plasminogen activator activity that is consistent with an endothelial product. It is possible that, at high doses, TNF may interact directly with vascular endothelium, leading to rapid and prolonged production of plasminogen activator inhibitor. There was a dose-response effect between TNF and release of tissue-type plasminogen activator. The release of tissue-type plasminogen activator was preceded by granulocytopenia, which may indicate an association between a proposed TNF-induced granulocyte-endothelial interaction in vivo and release of tissue-type plasminogen activator. IMPLICATIONS: These findings demonstrating the effects of TNF on the fibrinolytic system can be analyzed further in experimental systems to determine the implications for use of this agent as a biological response modifier in cancer therapy.

Fibrin-dependent fibrinolytic activity during extracorporeal circulation.

Cardiopulmonary By-Pass (CPB) Surgery may at times induce a haemostatic defect, at present not too well understood, causing severe bleeding from the operative site and chest tube drain. We present here some data on antigen increase in tissue Plasminogen Activator (tPA) and D 2 Dimer (D2D) detected during CPB and apparently not compensated by enhanced Plasminogen Activator Inhibitor type 1 (PAI 1) activity. tPA concentration (antigenic) ranged around 6.15 ng/ml (SD 5.6) before thoracotomy and 5.8 g/ml (SD 4.74) 5-10 minutes after a heparin 250 IU/Kg bolus injection. During CPB, tPA increased to 20.34 ng/ml (SD 9.17) before protamine infusion, and 16.93 ng/ml (SD 8.13) after heparin neutralization. As the D2D went up to 2000-4000 ng/ml (before/after protamine) and it was not correlated by fibrinogen consumption or FDP production, we find these observations suggestive of fibrin-dependent fibrinolytic activity, as an acquired haemostatic defect developed during CPB.

Coagulopathy and haemorrhage in human victims of Bothrops jararaca envenoming in Brazil.

Thirty-four patients envenomed by Bothrops jararaca in Brazil were studied. Of these, 20 (59%) had incoagulable blood associated with local and/or systemic bleeding and 10 of the 20 were thrombocytopenic. Among 14 patients with coagulable blood, 6 (43%) had bleeding symptoms and 3 (21%) were thrombocytopenic. High levels of von Willebrand factor (vWF), plasminogen activator inhibitor type 1 (PAI-1) and tissue type plasminogen activator (t-PA) antigens were also recorded in some patients with systemic bleeding with or without incoagulable blood. These substances may have been released from endothelial cells. Admission serum venom antigen levels were similar in both groups. The study indicated that systemic haemorrhage may occur in patients with coagulable blood and thrombocytopenia and that coagulopathy is not therefore the primary cause of haemorrhage.

Aspirin effect on the release of plasminogen activator inhibitors by human platelets.

Intrinsic plasminogen activators (PA) were tested in euglobulins (eug) of platelet poor plasma (PPP) with and without washed platelets (WP), treated or not with urokinase (UK), streptokinase (SK), collagen (Col) and aspirin (ASA) using fibrin plates method. A significant decrease of the fibrinolytic activity related to the presence and number of platelets was observed. We confirm the presence of platelet anti-UK and anti-SK activities. The former appears to be higher than the other activity. Low and high concentrations of Col stimulated the release of plasminogen activator-inhibitors (PA-I) from platelets, and ASA could not modify this release. Besides ASA might inhibit some PA release. The high concentration of Col was capable to release anti-UK and anti-SK activities from platelets and perhaps other intrinsic PA-I. The low concentration of Col was only capable to release intrinsic PA-I, suggesting that anti-UK and anti-SK needed a stronger stimuli to be released than intrinsic PA-I. We must consider the possibility that the PA-I and/or activators could be released by different metabolic pathways other than cyclooxygenase pathway.

The role of plasminogen activator in ovulation.

The role of plasminogen activator in ovulation was investigated using the inhibitor, trans-aminomethylcyclohexane carboxylic acid (t-AMCHA). In the regular cycle rat, the plasminogen activator activity of the follicles increased from the diestrus to the estrus phase. In the latter phase, a proteolytic enzyme which was not inhibited by t-AMCHA appeared. After ovulation, the plasminogen activator activity decreased. When ovulation was induced in immature rats by pregnant mare serum gonadotrophin and human chorionic gonadotrophin, remarkable fibrinolytic activity appeared in the ovaries immediately before ovulation. When t-AMCHA was given in the ovulation-induced rats, the fibrinolytic activity of the ovaries was suppressed, the number of ovulated ova decreased and the timing of ovulation was delayed. When t-AMCHA solution was given to rats in the proestrus phase, ovulation was almost completely suppressed, but aprotinin solution exerted no effect on ovulation. These results suggest that plasminogen activator is a key enzyme in ovulation, and that the chain reaction from plasminogen activator to proteolytic enzyme (including collagenase) is of greater importance than that of plasminogen activator to plasmin.