RESUMEN
Hepatocellular carcinoma (HCC) is a common malignant tumour, which has a poor prognosis. Surgical resection can be curative but most patients are inoperable and most chemotherapy agents have minimal activity in this disease. Seocalcitol, a vitamin D analogue, induces differentiation and inhibits growth in cancer cell lines and in vivo. The vitamin D receptor is expressed in hepatocytes and more abundantly in HCC cells. In total, 56 patients with inoperable advanced HCC were included in an uncontrolled study of oral Seocalcitol treatment for up to 1 year (with possible extension for responders). The dose was titrated according to serum calcium levels. The treatment effect was evaluated by regular CT scans. Out of 33 patients evaluable for tumour response, two had complete response (CR), 12 stable disease and 19 progressive disease. The CRs appeared after 6 and 24 months of treatment, and lasted for 29 and at least 36 months (patient still in remission when data censored). Seocalcitol was well tolerated; the most frequent toxicity was hypercalcaemia and related symptoms. Most patients tolerated a daily dose of 10 micro g of Seocalcitol. This is the first study showing activity, by reduction in tumour dimensions, of a differentiating agent in patients with an advanced bulky, solid tumour. Seocalcitol may have an effect in the treatment of HCC, especially in early disease when a prolonged treatment can be instituted. The survival benefit with or without tumour response should be determined in controlled studies.
Asunto(s)
Antineoplásicos/farmacología , Calcitriol/análogos & derivados , Calcitriol/farmacología , Carcinoma Hepatocelular/tratamiento farmacológico , Neoplasias Hepáticas/tratamiento farmacológico , Administración Oral , Adulto , Anciano , Anciano de 80 o más Años , Antineoplásicos/administración & dosificación , Antineoplásicos/efectos adversos , Calcitriol/administración & dosificación , Calcitriol/efectos adversos , Carcinoma Hepatocelular/patología , Progresión de la Enfermedad , Femenino , Humanos , Neoplasias Hepáticas/patología , Masculino , Persona de Mediana Edad , Receptores de Calcitriol/biosíntesis , Receptores de Calcitriol/fisiología , Resultado del TratamientoRESUMEN
Inoperable cancer of the exocrine pancreas responds poorly to most conventional anti-cancer agents, and new agents are required to palliate this disease. Seocalcitol (EB1089), a vitamin D analogue, can inhibit growth, induce differentiation and induce apoptosis of cancer cell lines in vitro and can also inhibit growth of pancreatic cancer xenografts in vivo. Thirty-six patients with advanced pancreatic cancer received once daily oral treatment with seocalcitol with dose escalation every 2 weeks until hypercalcaemia occurred, following which patients continued with maintenance therapy. The most frequent toxicity was the anticipated dose-dependent hypercalcaemia, with most patients tolerating a dose of 10-15 microg per day in chronic administration. Fourteen patients completed at least 8 weeks of treatment and were evaluable for efficacy, whereas 22 patients were withdrawn prior to completing 8 weeks' treatment and in 20 of these patients withdrawal was due to clinical deterioration as a result of disease progression. No objective responses were observed, with five of 14 patients having stable disease in whom the duration of stable disease was 82-532 days (median=168 days). The time to treatment failure (n=36) ranged from 22 to 847 days, and with a median survival of approximately 100 days. Seocalcitol is well tolerated in pancreatic cancer but has no objective anti-tumour activity in advanced disease. Further studies are necessary to determine if this agent has any cytostatic activity in this malignancy in minimal disease states.
Asunto(s)
Antineoplásicos/farmacología , Calcitriol/farmacología , Carcinoma/tratamiento farmacológico , Neoplasias Pancreáticas/tratamiento farmacológico , Administración Oral , Adulto , Anciano , Antineoplásicos/administración & dosificación , Antineoplásicos/efectos adversos , Calcitriol/administración & dosificación , Calcitriol/efectos adversos , Calcitriol/análogos & derivados , Carcinoma/patología , Progresión de la Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neoplasias Pancreáticas/patología , Análisis de Supervivencia , Resultado del TratamientoRESUMEN
BACKGROUND: The aim of this study was to evaluate the efficacy of the combination of epirubicin, cisplatin and ralitrexed (Tomudex). ECT, in patients with advanced oesophageal or gastric adenocarcinoma. Efficacy was assessed primarily as response rate and secondarily in terms of toxicity, time to progression and survival. PATIENTS AND METHODS: Twenty-one patients with histologically and/or cytologically proven unresectable (7) or metastatic (14) gastro-oesophageal adenocarcinoma, who had bi-dimensionally measurable disease, with ECOG performance status < or = 2. with adequate haematological, hepatic and renal function received first-line chemotherapy with epirubicin (50 mg/m2). cisplatin (60 mg/m2) and Tomudex (2.5 mg/m2), ECT, at three-weekly intervals. Treatment consisted of three cycles of chemotherapy, with a further three cycles if there was disease response or stabilisation. RESULTS: ECT is an active regimen in the treatment of advanced gastro-oesophageal adenocarcinoma with an overall intention-to-treat response rate of 29% (95% confidence intervals (CI): 11%-52%). In addition, 4 (19%) patients had stable disease. Median time to progression was 19 weeks (95% CI: 7-31 weeks). Median overall survival was 18 weeks (95% CI: 11-24 weeks). Seventeen patients failed to complete the six cycles of treatment due to disease progression (5). toxicity (3), non-toxic death (1 pulmonary embolism, 1 cardiac), severe allergy to epirubicin (1), patient decision (1) and five patients after the study was discontinued early due to toxicity. There were three toxic deaths: two due to sepsis complicating neutropaenia and one due to cardiorespiratory failure following drug induced enteritis. Nine patients experienced grade 3 or 4 neutropaenia, two patients experienced grade 3 or 4 nausea and vomiting and one patient had grade 4 diarrhoea. CONCLUSIONS: The combination of epirubicin, cisplatin and tomudex is active against advanced gastro-oesophageal adenocarcinoma but the toxicity suggests that further evaluation in a randomised comparison to ECF is not appropriate.
Asunto(s)
Adenocarcinoma/tratamiento farmacológico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias Esofágicas/tratamiento farmacológico , Neoplasias Gástricas/tratamiento farmacológico , Adenocarcinoma/patología , Adulto , Anciano , Protocolos de Quimioterapia Combinada Antineoplásica/administración & dosificación , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Cisplatino/administración & dosificación , Progresión de la Enfermedad , Hipersensibilidad a las Drogas , Enteritis/inducido químicamente , Epirrubicina/administración & dosificación , Neoplasias Esofágicas/patología , Femenino , Humanos , Infusiones Intravenosas , Masculino , Persona de Mediana Edad , Neutropenia/inducido químicamente , Embolia Pulmonar/inducido químicamente , Quinazolinas/administración & dosificación , Sepsis/inducido químicamente , Sepsis/mortalidad , Neoplasias Gástricas/patología , Análisis de Supervivencia , Tiofenos/administración & dosificación , Resultado del TratamientoRESUMEN
The rarity of endometrial stromal sarcoma (ESS) and its poor response to treatment provides fertile ground for investigational therapies. An accelerated regimen of carboplatin and paclitaxel is investigated. A patient with a recent history of treated tuberculosis of the lung represented with infertility and acute abdominal pain from suspected fibroids, and underwent a laparotomy with a diagnosis of a high-grade ESS. A novel therapeutic approach using a regimen of carboplatin and paclitaxel with the reinfusion of filgrastim-mobilized peripheral blood progenitor cells is described. A partial response was observed following six cycles of chemotherapy. Grade IV thrombocytopenia occurred after the last cycle, with recovery prior to pelvic radiotherapy. The patient remained well 1 year post-diagnosis. High-grade ESS is responsive to combination chemotherapy with paclitaxel and carboplatin, and requires further evaluation. The use of an accelerated regimen may also have contributed to the response and this question awaits randomized trials.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias Endometriales/tratamiento farmacológico , Sarcoma Estromático Endometrial/tratamiento farmacológico , Adulto , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Carboplatino/administración & dosificación , Carboplatino/efectos adversos , Neoplasias Endometriales/diagnóstico por imagen , Neoplasias Endometriales/patología , Femenino , Filgrastim , Factor Estimulante de Colonias de Granulocitos/administración & dosificación , Trasplante de Células Madre Hematopoyéticas , Humanos , Infusiones Intravenosas , Estadificación de Neoplasias , Paclitaxel/administración & dosificación , Paclitaxel/efectos adversos , Proteínas Recombinantes , Sarcoma Estromático Endometrial/diagnóstico por imagen , Sarcoma Estromático Endometrial/patología , Trombocitopenia/inducido químicamente , Tomografía Computarizada por Rayos X , Acondicionamiento Pretrasplante , Tuberculosis Pulmonar/complicacionesRESUMEN
ONO-4007 is a synthetic analogue of the lipid A moiety of bacterial lipopolysaccharide, which exhibits antitumor activity by the induction of intratumoral tumor necrosis factor alpha, the potentiation of tumor-infiltrating macrophages, and the inhibition of angiogenesis. Interleukin (IL)-1 alpha, IL-6, and IL-12 induction by ONO-4007 activates cytotoxic natural killer cells to up-regulate IFN-gamma and nitric oxide synthase activity. ONO-4007 was given to 24 patients (13 males and 11 females; median age, 53 years) as a 30-min i.v. infusion on day 1, followed on day 15 by a first treatment cycle consisting of three weekly infusions at the same dose, followed by a rest period of 1 week. Cohorts of six patients received up to a maximum of four treatment cycles at increasing dose levels (75, 100, and 125 mg). The maximum tolerated dose was 125 mg, with grade 3 National Cancer Institute Common Toxicity Criteria toxicity (rigors with cyanosis) occurring in two of six patients at this dose level. An additional six patients were treated at 100 mg, the dose below the maximum tolerated dose. Other toxicities included grade 2 National Cancer Institute Common Toxicity Criteria myalgia, nausea, and hypotension. The pharmacokinetics of ONO-4007 appeared to be independent of dose and showed linearity with respect to time. ONO-4007 has a low systemic clearance (approximately 1.3 ml/min) and a small volume of distribution (5-8 liters) with a long t1/2 of 74-95 h. The administration of ONO-4007 was shown to result in a significant increase in circulating levels of tumor necrosis factor alpha and IL-6. No objective antitumor responses were observed. Seven patients maintained stable disease for at least two cycles, whereas five patients maintained stable disease for the full four-cycle duration of the study. Additional studies are required to determine the antitumor activity of ONO-4007.
Asunto(s)
Antineoplásicos/efectos adversos , Antineoplásicos/farmacocinética , Lípido A/análogos & derivados , Neoplasias/tratamiento farmacológico , Adulto , Anciano , Antineoplásicos/administración & dosificación , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Infusiones Intravenosas , Lípido A/administración & dosificación , Lípido A/efectos adversos , Lípido A/farmacocinética , Masculino , Tasa de Depuración Metabólica , Persona de Mediana Edad , Neoplasias/sangre , Factor de Necrosis Tumoral alfa/análisisRESUMEN
BACKGROUND: Adenocarcinoma of unknown primary comprises up to 10% of metastatic malignant disease. With few exceptions this diagnosis carries a very poor prognosis of a few months with minimal survival advantage to chemotherapy. However there is the possibility that chemotherapy can improve symptom control and quality of life. PATIENTS AND METHODS: Forty-four patients with adenocarcinoma of unknown primary received CFTam chemotherapy regimen (5-FU 750 mg/m2/day by protracted infusion for five days, cisplatin 60 mg/m2 once and tamoxifen 20 mg daily on a 21-day cycle). Disease response and toxicity were collected and survival compared to patients who were not treated or who received different chemotherapy regimens. RESULTS: Overall response to CFTam was 27% with a median duration of 10 months (range 4-26 months). The chemotherapy was well tolerated with no grade 4 non-haematological toxicity and only three patients (7%) grade 4 neutropaenia with only two (5%) patients developing sepsis. There were no toxic deaths. Performance status was maintained or improved in responders. CONCLUSIONS: CFTam is a well tolerated chemotherapy regimen with similar efficacy to other regimens described in the treatment of adenocarcinoma of unknown primary. In the absence of a significant survival advantage there is a need to conduct randomised trials of chemotherapy versus best supportive care to quantify any improvement in quality of life or symptom control.
Asunto(s)
Adenocarcinoma/tratamiento farmacológico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias Primarias Desconocidas/tratamiento farmacológico , Adenocarcinoma/mortalidad , Adenocarcinoma/secundario , Adulto , Anciano , Anciano de 80 o más Años , Antimetabolitos Antineoplásicos/administración & dosificación , Cisplatino/administración & dosificación , Intervalos de Confianza , Femenino , Fluorouracilo/administración & dosificación , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Neoplasias Primarias Desconocidas/mortalidad , Neoplasias Primarias Desconocidas/patología , Análisis de Supervivencia , Tasa de Supervivencia , Resultado del TratamientoRESUMEN
Thirty-nine patients with inoperable adenocarcinoma of the pancreas were studied (27 male, 12 female; median age 60 years, range 39-75 years). All patients received chemotherapy with continuous infusion 5-fluorouracil with intravenous bolus epirubicin followed by cisplatin, repeated every 21 days for a total of six cycles and were evaluable for response. Serum CA19-9 concentrations were obtained at baseline and before each cycle. A rise or fall in the tumour marker was defined as a greater than 15% increase or decrease in the marker on two consecutive occasions 3 weeks apart. A plateau in the tumour marker was defined as a less than 15% decrease or increase on two occasions. Changes in marker expression were compared with serial computerized tomography scanning before treatment and after the third and sixth cycle of chemotherapy. Thirty-five of 39 patients had an elevated CA19-9 (87.9%). Thirteen (36.2%) exhibited a decrease, seven (19.4%) a plateau and 16 (44.4%) patients had a progressive rise in serum CA19-9. The sensitivity of CA19-9 was 67% for predicting a partial response and 86% for progressive disease. The median survival for the 13 patients exhibiting a reduction was 333 days, for the seven patients exhibiting a plateau 253 days and for those who had a progressive rise 185 days. The difference in median survival between the group of patients with > 15% decrease and those with > 15% increase of CA19-9 was significant (P = 0.001). In the cohort of patients who exhibited a reduction in CA19-9, no tumour progression was seen, and the reduction occurred during the first three cycles of treatment. Thus, interval scanning may be avoided in this group of patients.
Asunto(s)
Adenocarcinoma/diagnóstico , Antígeno CA-19-9/análisis , Neoplasias Pancreáticas/diagnóstico , Adenocarcinoma/tratamiento farmacológico , Adenocarcinoma/inmunología , Adulto , Anciano , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neoplasias Pancreáticas/tratamiento farmacológico , Neoplasias Pancreáticas/inmunología , Estudios Retrospectivos , Análisis de SupervivenciaRESUMEN
Within the last decade haemopoietic growth factors have become established in the pharmacopoeia of oncology. In the form of granulocyte colony-stimulating factor (G-CSF), and to a lesser extent granulocyte-macrophage colony-stimulating factor (GM-CSF), these proteins are routinely used to accelerate restoration of neutrophil count after chemotherapy or bone marrow transplant. Their main advance has been the development of mobilisation protocols. Peripheral blood progenitor cells are induced to egress from the bone marrow and re-transfusion after myelosuppressive chemotherapy allows for a simple and more rapid form of autologous transplantation than bone marrow transplantation. This review will give a brief overview of the biology of haemopoiesis in relation to growth factors and the potential lines of further research. Although the established clinical uses of G-CSF will be discussed the main focus will be on the developmental applications, such as ex vivo haemopoiesis, dose intensification schedules and the application of growth factors in the therapy of haematological malignancies. The relevance of novel or more recently introduced recombinant haemopoietic growth factors will also be discussed in relation to these indications.
RESUMEN
The aim of this study was to determine whether palliative chemotherapy accelerates the rate of biliary stent occlusion, in patients with a malignant biliary obstruction. Such treatment can induce neutropenia and increase the risk of bacterial sepsis. Overgrowth of bacteria within the bile of patients receiving chemotherapy could accelerate the rate of stent occlusion. Retrospective analysis of treatment records for 80 consecutive patients with a diagnosis of adenocarcinoma arising from the pancreas, bile ducts or gall bladder was conducted. Two groups were identified, those with a biliary stent in situ (primary stent group: 47/80; 59%) at the time of referral and those without (no stent group: 33/80; 41%). The majority of patients went on to receive chemotherapy, 64% and 70% in the primary stent group and no stent group, respectively. The rate of febrile neutropenia was similar in the two groups (5% versus 7% of all chemotherapy cycles in the primary stent group and no stent group, respectively). The rate of stent occlusion was not significantly different between those exposed to chemotherapy (37%; 95% CI 20-54%) and those unexposed (39%; 95% CI 19-59%). Similarly, the mean duration of patency was not shortened by chemotherapy (105 days in the chemotherapy group versus 119 days in the non-chemotherapy group; P = 0.97, Mann-Whitney U-test). We conclude that there is no evidence of increased rate of bile duct-related complications in patients receiving chemotherapy. In particular, we find no indication for the use of prophylactic antibiotics.
Asunto(s)
Antineoplásicos/efectos adversos , Neoplasias del Sistema Biliar/complicaciones , Colestasis/terapia , Neoplasias Pancreáticas/complicaciones , Stents/efectos adversos , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias del Sistema Biliar/tratamiento farmacológico , Colestasis/etiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Infecciones Oportunistas/inducido químicamente , Cuidados Paliativos , Neoplasias Pancreáticas/tratamiento farmacológico , Recurrencia , Estudios RetrospectivosRESUMEN
To assess the efficacy and toxicity of an outpatient combination chemotherapy in small-cell lung cancer (SCLC), we treated 70 consecutive patients with epirubicin 80 mg m(-2) i.v. on day 1 and etoposide 200 mg o.d. p.o. on days 1-4 (EE) at 3-weekly intervals. The median age of patients was 64 years (range 39-84). The male-female ratio was 42:28 and 35 (50%) had metastatic disease. Fifty-seven patients were evaluable for response. The overall response rate was 64.4%, including 14 (23.7%) complete responses and 24 (40.7%) partial responses. Median time to progression was 7 months in responders and 8 months in patients with limited disease. The median survival in patients with limited disease was 10.5 months (range 0.5-70 +) and 7 months (range 0.5-24) in those with extensive disease. Improvement of symptoms occurred in 79% of patients with shortness of breath, 80% with cough, 81% with haemoptysis and 68% with pain. In 19 patients an increase in body weight was noted. Major (WHO grade 3/4) toxicities were neutropenia in 13 (18.5%) patients, alopecia in 33 (47.1%) patients, mucositis in 15 (21.4%) patients, anorexia in eight patients (11.4%), nausea and vomiting in six patients (8.5%) and diarrhoea in 4 (5.7%) patients. In conclusion, EE is an active and well-tolerated outpatient regimen in the treatment of SCLC. The survival data in this unselected group of patients were disappointing and the possible explanations for this are discussed.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Carcinoma de Células Pequeñas/tratamiento farmacológico , Neoplasias Pulmonares/tratamiento farmacológico , Administración Oral , Adulto , Anciano , Anciano de 80 o más Años , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Carcinoma de Células Pequeñas/mortalidad , Carcinoma de Células Pequeñas/patología , Epirrubicina/administración & dosificación , Etopósido/administración & dosificación , Femenino , Humanos , Infusiones Intravenosas , Neoplasias Pulmonares/mortalidad , Neoplasias Pulmonares/patología , Masculino , Persona de Mediana Edad , Metástasis de la Neoplasia , Estadificación de Neoplasias , Pacientes Ambulatorios , Tasa de SupervivenciaRESUMEN
Carcinomas of the exocrine pancreas respond poorly to most chemotherapy regimens. Recently continuous infusional 5-fluorouracil (200 mg m-(2)day-1) with 3 weekly cisplatin (60 mg m-2) and epirubicin (50 mg m-2) (the ECF regimen) has proven to be an active regimen in gastric and breast cancer and consequently worthy of further study in pancreatic cancer. Thirty-five patients were treated with the ECF regimen as above, of whom 29 were evaluable for response and 32 were evaluable for toxicity. The mean age was 59 years (range 37-75). Sixteen patients had locally advanced disease at presentation and 19 had metastases. Objective tumour responses were documented in five (17.3%) patients who achieved a partial response; in 18 (62%) patients there were no change and six (20.7%) patients progressed on therapy. Patients with either stable disease or partial response had a significantly improved overall survival (median = 253 days) compared with patients who progressed (median = 170 days; P = 0.01). Grade 3/4 (WHO) toxicity (all cycles) included alopecia in 18 (56%) patients, nausea/vomiting in eight (25%) stomatitis in three (9%) and diarrhoea in seven (22%) patients, with rhinorrhoea and excessive lacrimation in one patient each. Neutropenic sepsis occurred in 13 cycles in ten patients, and there was one toxic death due to sepsis. There were eight other episodes of non-neutropenic sepsis requiring hospital admission. Fourteen patients (40%) experienced complications with their Hickman lines, including thrombotic episodes (six patients) or their line falling out (five patients). ECF can prolong survival in patients with locally advanced or metastatic pancreatic cancer who demonstrate a response or stabilisation of their disease. However, this is associated with considerable toxicity.
Asunto(s)
Adenocarcinoma/tratamiento farmacológico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Cisplatino/administración & dosificación , Epirrubicina/administración & dosificación , Fluorouracilo/administración & dosificación , Neoplasias Pancreáticas/tratamiento farmacológico , Adulto , Anciano , Femenino , Humanos , Infusiones Intravenosas , Masculino , Persona de Mediana EdadRESUMEN
The neu oncogene is activated by a point mutation within its transmembrane domain that results in the substitution of glutamic acid for valine at position 664, and is associated with constitutive activation of the tyrosine kinase. It has been proposed that the mutation allows for stabilization of homodimers of the receptor that are necessary for transduction of the mitogenic signal. To investigate the role of the alpha-helical transmembrane sequence in the function of neu, we constructed an expression vector to produce a variety of short transmembrane neu proteins, lacking ligand binding or intracellular kinase domains. Such sequences should interact with full-length receptors and prevent receptor dimerization and thus act as specific inhibitors of function. These small proteins all included a pentapeptide from position 661-665, which has been proposed to be necessary for packing. We show that the short transmembrane molecules are expressed at the cell surface and can retard the growth of neu-transformed cells in monolayers, as colonies in soft agar and as tumours in animals. As predicted by molecular modelling, the magnitude of inhibition depended on the nature of the packing surface, suggesting that the neu transmembrane domain is directly involved in neu protein dimerization.
Asunto(s)
Transformación Celular Neoplásica/genética , Mutación/fisiología , Proteínas Proto-Oncogénicas/química , Células 3T3 , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales , Secuencia de Bases , División Celular , Membrana Celular/química , Regulación hacia Abajo , Ratones , Ratones Desnudos , Datos de Secuencia Molecular , Trasplante de Neoplasias , Proteínas Proto-Oncogénicas/análisis , Proteínas Proto-Oncogénicas/fisiología , Receptor ErbB-2 , Relación Estructura-ActividadRESUMEN
There is no evidence for activation of c-erbB2 by mutation in human cancer. Gene rearrangements are observed at low frequency, but there are a proportion of human cancers that are associated with c-erbB2 gene amplification and membrane protein overexpression. The human cancers so affected are adenocarcinomas of the breast, ovary, stomach, and bladder, with up to 20% of primary lesions exhibiting either increased gene copy number and/or excess membrane staining. The c-erbB2 protein on these tumors could be used as a therapeutic target, as in monoclonal antibody targetted therapy already being assessed in c-erbB2 positive breast cancer. Other possible therapeutic strategies include the development of tyrosine kinase inhibitors or ligand antagonists.
Asunto(s)
Regulación Neoplásica de la Expresión Génica , Proteínas de Neoplasias/genética , Neoplasias/enzimología , Proteínas Tirosina Quinasas/genética , Proteínas Proto-Oncogénicas/genética , Proto-Oncogenes , Adenocarcinoma/enzimología , Adenocarcinoma/genética , Animales , Transformación Celular Neoplásica/genética , Inducción Enzimática , Amplificación de Genes , Humanos , Proteínas de Neoplasias/biosíntesis , Neoplasias/genética , Oncogenes , Especificidad de Órganos , Fosforilación , Procesamiento Proteico-Postraduccional , Proteínas Tirosina Quinasas/biosíntesis , Proteínas Proto-Oncogénicas/biosíntesis , Ratas , Receptor ErbB-2RESUMEN
The neu proto-oncogene may be converted into a dominantly transforming oncogene by a single point mutation. Substitution of a valine residue at position 664 in the transmembrane region with glutamic acid activates the tyrosine kinase of the molecule and is associated with increased receptor dimerization. Previously we have proposed a model in which the glutamic acid side chain stabilizes receptor dimerization by hydrogen bonding. Other models have been proposed in which the mutation leads to a conformational change in the transmembrane region mimicking that assumed to occur following binding of a natural ligand. Synthetic peptides representing part of the transmembrane region were prepared. Some residues were replaced with serine in order to improve peptide solubility to allow purification and analysis. Both the peptides containing valine and glutamic acid dissolved in water and in an artificial lipid monolayer. The structures of the peptides were determined by NMR spectroscopy to be alpha-helical. No significant difference in conformation was observed between the two peptides. This result does not support the model proposing a conformational change. The receptor structures determined experimentally do allow alternative models involving receptor transmembrane region packing.
Asunto(s)
Receptores ErbB/química , Proteínas de la Membrana/química , Proteínas Oncogénicas/química , Proteínas Proto-Oncogénicas/química , Secuencia de Aminoácidos , Animales , Receptores ErbB/genética , Concentración de Iones de Hidrógeno , Espectroscopía de Resonancia Magnética , Proteínas de la Membrana/genética , Modelos Moleculares , Datos de Secuencia Molecular , Mutación , Proteínas Oncogénicas/genética , Fragmentos de Péptidos/química , Conformación Proteica , Proteínas Proto-Oncogénicas/genética , Ratas , Receptor ErbB-2RESUMEN
The effect of PGI2, 6-oxo-PGE1 and PGE1 on ADP-induced human platelet aggregation has been assessed in whole blood and in blood centrifuged to prepare platelet-rich plasma (PRP). PGI2 was the most potent anti-aggregatory agent in both media. The concentration of PGI2 required to produce 50% inhibition of platelet aggregation was approximately 0.3 ng ml-1 in each case. In contrast both E series prostaglandins exhibited significantly greater (400-700%) anti-aggregatory activity when tested in whole blood than when tested in PRP. Since whole blood presumably represents a truer reflection of platelet reactivity in-vivo, we believe that the potency of 6-oxo-PGE1 (and PGE1) as inhibitors of platelet aggregation has been underestimated in previous experiments using PRP. In human whole blood 6-oxo-PGE1 has approximately 40% the anti-aggregatory activity of PGI2. The reasons for the increased anti-aggregatory potency of E series prostaglandins in whole blood is not known. We suggest that 6-oxo-PGE1 and PGE1 (but not PGI2) may prevent the release of pro-aggregatory ADP from red blood cells thereby enhancing their ability to inhibit platelet aggregation.
Asunto(s)
Agregación Plaquetaria/efectos de los fármacos , Prostaglandinas E/farmacología , Vasodilatadores/farmacología , Adulto , Alprostadil , Relación Dosis-Respuesta a Droga , Epoprostenol/farmacología , Humanos , Técnicas In Vitro , MasculinoRESUMEN
Flavonoid drugs (rutin, naringenin and quercetin) were compared with indomethacin and sulphasalazine as inhibitors of rat and rabbit renal 9-hydroxyprostaglandin dehydrogenase, prostaglandin synthesis (bovine seminal vesicle microsomes) and inactivation (rabbit colon 100,000 g supernatant), vascular PGI2 formation (rat aortic rings) and for effects on platelet aggregation and on the isolated rat stomach strip. Rutin and naringenin potently inhibited rabbit renal conversion of PGI2 and PGF2 alpha to 6-oxoPGE1 and PGE2, respectively, but had no effect on rat renal 9-hydroxyprostaglandin dehydrogenase activity, prostaglandin breakdown, vascular PGI2 synthesis, platelet aggregation or the anti-aggregatory effect of PGI2 and 6-oxoPGE1. High concentrations (100 microM) of both drugs inhibited the spasmogenic effect of PGI2 on the rat stomach strip. Naringenin and quercetin (1 mM) inhibited whilst rutin (1 mM) stimulated microsomal prostaglandin synthesis. These results suggest that rutin and naringenin may be useful experimental tools to study the biological roles of 6-oxoPGE1.
Asunto(s)
Alprostadil/análogos & derivados , Epoprostenol/metabolismo , Flavonoides/farmacología , Corteza Renal/metabolismo , Prostaglandinas E/biosíntesis , Prostaglandinas F/metabolismo , Animales , Ácido Araquidónico , Ácidos Araquidónicos/metabolismo , Bovinos , Colon/efectos de los fármacos , Colon/metabolismo , Dinoprost , Dinoprostona , Corteza Renal/efectos de los fármacos , Masculino , Microsomas/metabolismo , Conejos , Vesículas Seminales/metabolismo , Relación Estructura-ActividadRESUMEN
1. Human platelet-rich plasma incubated at 37 degrees C generates an antiaggregatory prostaglandin which is spasmogenic on gastrointestinal smooth muscle. 2. Platelet-rich plasma from female donors generated more biological activity and was more sensitive to the anti-aggregatory activity of added prostaglandin I2 (PGI2) compared with that from age-matched male controls. 3. After thin-layer chromatography of extracted platelet-rich plasma, biological activity was detected in a zone which co-chromatographed with 6-oxoprostaglandin E1. 4. Neither extracted platelet-rich plasma nor authentic 6-oxoprostaglandin E1 were inactivated following incubation with purified 15-hydroxyprostaglandin dehydrogenase. 5. The relevance of these findings for regulating platelet reactivity is discussed.