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1.
Ann Oncol ; 26(2): 407-14, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25421877

RESUMO

BACKGROUND: Four international study groups undertook a large study in resectable osteosarcoma, which included two randomised controlled trials, to determine the effect on survival of changing post-operative chemotherapy based on histological response. PATIENTS AND METHODS: Patients with resectable osteosarcoma aged ≤40 years were treated with the MAP regimen, comprising pre-operatively of two 5-week cycles of cisplatin 120 mg/m(2), doxorubicin 75 mg/m(2), methotrexate 12 g/m(2) × 2 (MAP) and post-operatively two further cycles of MAP and two cycles of just MA. Patients were randomised after surgery. Those with ≥10% viable tumour in the resected specimen received MAP or MAP with ifosfamide and etoposide. Those with <10% viable tumour were allocated to MAP or MAP followed by pegylated interferon. Longitudinal evaluation of quality of life was undertaken. RESULTS: Recruitment was completed to the largest osteosarcoma study to date in 75 months. Commencing March 2005, 2260 patients were registered from 326 centres across 17 countries. About 1334 of 2260 registered patients (59%) were randomised. Pre-operative chemotherapy was completed according to protocol in 94%. Grade 3-4 neutropenia affected 83% of cycles and 59% were complicated by infection. There were three (0.13%) deaths related to pre-operative chemotherapy. At definitive surgery, 50% of patients had at least 90% necrosis in the resected specimen. CONCLUSIONS: New models of collaboration are required to successfully conduct trials to improve outcomes of patients with rare cancers; EURAMOS-1 demonstrates achievability. Considerable regulatory, financial and operational challenges must be overcome to develop similar studies in the future. The trial is registered as NCT00134030 and ISRCTN 67613327.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Ósseas/tratamento farmacológico , Osteossarcoma/tratamento farmacológico , Adolescente , Neoplasias Ósseas/cirurgia , Criança , Cisplatino/administração & dosagem , Cisplatino/efeitos adversos , Terapia Combinada , Doxorrubicina/administração & dosagem , Doxorrubicina/efeitos adversos , Etoposídeo/administração & dosagem , Etoposídeo/efeitos adversos , Feminino , Humanos , Ifosfamida/administração & dosagem , Ifosfamida/efeitos adversos , Interferon-alfa/administração & dosagem , Interferon-alfa/efeitos adversos , Masculino , Metotrexato/administração & dosagem , Metotrexato/efeitos adversos , Terapia Neoadjuvante , Osteossarcoma/cirurgia , Polietilenoglicóis/administração & dosagem , Polietilenoglicóis/efeitos adversos , Qualidade de Vida , Projetos de Pesquisa , Adulto Jovem
2.
Ann Oncol ; 23(11): 2970-2976, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22771824

RESUMO

BACKGROUND: The Italian Sarcoma Group and the Scandinavian Sarcoma Group designed a joint study to improve the prognosis for patients with Ewing's family tumors and synchronous metastatic disease limited to the lungs, or the pleura, or a single bone. PATIENTS AND METHODS: The study was opened in 1999 and closed to the enrollment in 2008. The program consisted of intensive five-drug combination chemotherapy, surgery and/or radiotherapy as local treatment, and consolidation treatment with high-dose busulfan/melphalan plus autologous stem cell rescue and total-lung irradiation. RESULTS: During the study period, 102 consecutive patients were enrolled. The median follow-up was 62 months (range 24-124). The 5-year event-free survival probability was 0.43 [standard deviation (SD) = 0.05] and the 5-year overall survival probability was 0.52 (SD = 0.052). Unfavorable prognostic factors emerging on multivariate analysis were a poor histological/radiological response at the site of the primary tumor [relative risk (RR) = 3.4], and incomplete radiological remission of lung metastases after primary chemotherapy (RR = 2.6). One toxic death and one secondary leukemia were recorded. CONCLUSIONS: This intensive approach is feasible and long-term survival is achievable in ∼50% of patients. New treatment approaches are warranted for patients responding poorly to primary chemotherapy.


Assuntos
Antineoplásicos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Ósseas/secundário , Neoplasias Pulmonares/secundário , Agonistas Mieloablativos/uso terapêutico , Sarcoma de Ewing/terapia , Adolescente , Adulto , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Neoplasias Ósseas/terapia , Bussulfano/uso terapêutico , Criança , Pré-Escolar , Terapia Combinada , Ciclofosfamida/uso terapêutico , Etoposídeo/uso terapêutico , Feminino , Humanos , Ifosfamida/uso terapêutico , Neoplasias Pulmonares/radioterapia , Neoplasias Pulmonares/terapia , Masculino , Melfalan/uso terapêutico , Metástase Neoplásica/tratamento farmacológico , Metástase Neoplásica/radioterapia , Prognóstico , Sarcoma de Ewing/tratamento farmacológico , Sarcoma de Ewing/radioterapia , Sarcoma de Ewing/secundário , Transplante de Células-Tronco , Vincristina/uso terapêutico , Adulto Jovem
3.
Br J Cancer ; 106(2): 297-306, 2012 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-22173669

RESUMO

BACKGROUND: This study aims to provide reasons for the poor sarcoma-related survival in patients with radiation-induced sarcoma (RIS). METHODS: We performed a case-control study comparing sarcoma-related survival of 98 patients with RIS to that of 239 sporadic high-grade malignant sarcomas. RESULTS: The cumulative sarcoma-related 5-year survival was 32% (95% confidence interval (CI): 22-42) for patients with RIS vs 51% (95% CI: 44-58) for controls (P<0.001). Female gender, central tumour site and incomplete surgical remission were significantly more frequent among RIS patients than in controls. In multivariate analysis incomplete surgical remission (hazard ratio (HR) 4.48, 95% CI: 3.08-6.52), metastases at presentation (HR 2.93, 95% CI: 1.95-4.41), microscopic tumour necrosis (HR 1.88, 95% CI: 1.27-2.78) and central tumour site (HR 1.71, 95% CI: 1.18-2.47) remained significant adverse prognostic factors, but not sarcoma category (RIS vs sporadic). CONCLUSION: The poor prognosis of RIS patients are not due to the previous radiotherapy per se, but related to the unfavourable factors - central tumour site, incomplete surgical remission, microscopic tumour necrosis and the presence of metastases, the two former factors overrepresented in RIS.


Assuntos
Neoplasias Induzidas por Radiação/patologia , Sarcoma/patologia , Taxa de Sobrevida , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Prognóstico , Sarcoma/etiologia
4.
Ann Oncol ; 22(5): 1221-1227, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21059639

RESUMO

BACKGROUND: High-dose chemotherapy (HDT) was added to conventional chemotherapy in Ewing sarcoma family tumor (EFT) patients, poor responders (PRs) to induction chemotherapy in order to improve their survival. PATIENTS AND METHODS: Patients aged ≤40 years with nonmetastatic Ewing sarcoma (ES) received vincristine (V), doxorubicin (A), cyclofosfamide (C), actinomycin (Ac), ifosfamide (I) and etoposide (E) (VACAc-IE regimen) as induction chemotherapy. As maintenance treatment, good responders (GR) received nine cycles of VACAc-IE regimen. PRs received three cycles of VAC-IE, mobilizing cycle with CE and HDT with Busulfan and Melphalan with stem cell support. RESULTS: Three hundred patients [median age 15 years (3-40 years)] entered the study. One patient refused local treatment, 242 (81%) underwent surgery [with radiotherapy (RT) in 80] and 57 (19%) RT alone. No toxic deaths were recorded. Overall GR were 146 (49%). Twenty-eight PR did not receive HDT. At a median follow-up of 64 months (21-116 months), 5-year overall and event-free survival (EFS) were 75% and 69%, respectively. Five-year EFS was 75% for GR, 72% for PR treated with HDT and 33% for PR who did not receive HDT. CONCLUSIONS: High-dose therapy added to the VACA-IE regimen in PR patients is feasible and effective. Selected groups of patients with ES can benefit from HDT.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Ósseas/terapia , Transplante de Células-Tronco de Sangue Periférico , Sarcoma de Ewing/terapia , Adolescente , Adulto , Neoplasias Ósseas/mortalidade , Bussulfano/uso terapêutico , Criança , Pré-Escolar , Ciclofosfamida/uso terapêutico , Dactinomicina/uso terapêutico , Intervalo Livre de Doença , Doxorrubicina/uso terapêutico , Etoposídeo/uso terapêutico , Feminino , Humanos , Ifosfamida/uso terapêutico , Estimativa de Kaplan-Meier , Masculino , Melfalan/uso terapêutico , Agonistas Mieloablativos/uso terapêutico , Sarcoma de Ewing/mortalidade , Vincristina/uso terapêutico , Adulto Jovem
5.
Cancer Treat Res ; 152: 339-53, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-20213400

RESUMO

The introduction of multi-agent chemotherapy dramatically improved the outcome for patients with osteosarcoma. However, we appear to have reached a plateau in outcome with a long-term event-free survival of 60-70%. Therefore, detection of further improvements will likely require larger numbers of patients. This goal is best achieved via randomized clinical trials (RCTs) requiring large-scale cooperation and collaboration. With this background, four multinational groups agreed on the merits of collaboration: Children's Oncology Group (COG), Cooperative Osteosarcoma Study Group (COSS), European Osteosarcoma Intergroup (EOI) and Scandinavian Sarcoma Group (SSG); they designed a study to determine whether altering postoperative therapy based on histological response improved the outcome. The study design includes a backbone of 10 weeks of preoperative therapy using MAP (methotrexate, Adriamycin and cisplatin). Following surgery, patients are stratified according to histological response. Patients classified as "good responders" (>or=90% necrosis) are randomized to continue MAP or to receive MAP followed by maintenance pegylated interferon, while "poor responders" (<90% necrosis) are randomized to either continue MAP or to receive MAPIE (MAP+ifosfamide, etoposide). The design includes the registration of 1,400 patients over 4 years as well as the evaluation of quality of life using two different instruments. The group has established an efficient infrastructure to ensure successful implementation of the trial. This has included the EURAMOS Intergroup Safety Desk, which has established an international system for SAE, SAR and SUSAR reporting to the relevant competent authorities and ethics committees for each participating country. The group has also developed trial site monitoring and data center audits with funding from the European Science Foundation (ESF). The ESF has also funded three training courses to familiarize institutional staff with the requirements of multinational GCP trials. We have established a successful collaboration, and as of February 2008, 901 patients have been enrolled (COG 448; COSS 226; EOI 181; SSG 46) from 249 institutions in 16 different countries. As expected, 80% of the patients are <18 years of age, and accrual into the Quality of Life sub-study is proceeding as planned with 90% of the subjects agreeing to participate. International awareness is increasing and procedures for applicant countries wishing to join the collaboration have been implemented. Details about EURAMOS can be found at www.euramos.org. International trials in rare diseases are practicable with appropriate funding, planning and support. Although the implementation of such trials is difficult and time consuming, it is a worthwhile effort to rapidly complete RCTs and identify interventions that will improve the outcome of all osteosarcoma patients.EURAMOS-1 is the fastest accruing osteosarcoma trial and is already the largest osteosarcoma study conducted.


Assuntos
Neoplasias Ósseas/tratamento farmacológico , Osteossarcoma/tratamento farmacológico , Neoplasias Ósseas/mortalidade , Comportamento Cooperativo , Humanos , Cooperação Internacional , Osteossarcoma/mortalidade , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto
6.
J Pathol ; 209(4): 492-500, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16721726

RESUMO

Previous studies have suggested that amplification of genes, notably the TOP2A gene, on chromosome arm 17q may be important for the development of malignant peripheral nerve sheath tumour (MPNST). In order to study the frequency, distribution, and chromosomal organization of rearrangements at 17q, interphase and metaphase fluorescence in situ hybridization (FISH) were used to evaluate copy number changes at 17q in 28 MPNSTs. Increased copy numbers were seen for the ERBB2 and TOP2A genes in eight and nine cases, respectively, supporting a potential role for these two genes in MPNST tumourigenesis. Net gain of distal 17q material was observed in 16 of the 28 MPNSTs, with high-level gain in three cases, and was associated with poor outcome. Among the 26 patients for whom follow-up data were available, gain of distal 17q was present in 11 of 12 tumours that had metastasized, compared with 4 of 14 of those that had not metastasized. Detailed FISH mapping analysis of metaphase spreads identified a 2 Mb commonly gained/amplified region at 17q25. Among the genes mapping to this region, BIRC5, which encodes the baculoviral IAP repeat-containing protein 5/survivin protein, is a strong candidate target gene for amplification, as it has been previously shown to be overexpressed in neurofibromatosis type 1-associated MPNST. Three other genes that co-amplified with BIRC5 represent other potential candidate genes: PTDSR involved in apoptosis; SEPT9 overexpressed in human malignant brain tumours; and SOCS3 involved in cell survival and differentiation of neurons.


Assuntos
Cromossomos Humanos Par 17 , Genes Neoplásicos , Proteínas Associadas aos Microtúbulos/genética , Proteínas de Neoplasias/genética , Neoplasias de Bainha Neural/genética , Sarcoma/genética , Adolescente , Adulto , Idoso , Criança , Bandeamento Cromossômico , DNA Topoisomerases Tipo II/genética , Feminino , Seguimentos , Amplificação de Genes , Dosagem de Genes , Genes erbB-2 , Humanos , Hibridização in Situ Fluorescente , Proteínas Inibidoras de Apoptose , Interfase , Masculino , Metáfase , Pessoa de Meia-Idade , Neoplasias de Bainha Neural/patologia , Neoplasias de Bainha Neural/secundário , Neurofibromatose 1/genética , Neurofibromatose 1/patologia , Sarcoma/patologia , Sarcoma/secundário , Survivina
7.
Ann Oncol ; 15(7): 1072-8, 2004 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-15205201

RESUMO

BACKGROUND: Burkitt's/Burkitt-like lymphoma (BL/BLL) are highly aggressive lymphomas mainly affecting children and young adults. We report the results in adolescent and adult patients with the use of three successive regimens. PATIENTS AND METHODS: Forty-nine patients aged 15-70 years admitted to the Norwegian Radium Hospital in the period 1982-2001 with a diagnosis of BL/BLL on histological review and who were given chemotherapy with curative intent are included in this analysis. Up to 1987 patients were given doxorubicin-based chemotherapy supplemented with intravenous and intrathecal methotrexate (MmCHOP). From 1987 to 1994, patients who obtained complete remission upon this regimen were consolidated with high-dose therapy with stem-cell support (MmCHOP + HDT). In 1995 we introduced as frontline therapy the German Berlin-Frankfurt-Munster (BFM) regimen. RESULTS: By intention to treat analyses, the progression-free survival rates for patients who received MmCHOP (n=13), MmCHOP + HDT (n=17) or BFM therapy (n=19) are 30.8%, 70.6% and 73.7%, respectively. In the groups of patients who received either the BFM regimen or MmCHOP + HDT, all patients who obtained complete remission upon induction therapy are continuously disease free. There was no treatment-related death. CONCLUSIONS: BL/BLL in adolescents and adults can successfully be treated with 5-day blocks of intensified chemotherapy such as the BFM regimen or CHOP/methotrexate-based chemotherapy consolidated with high-dose therapy. Using the BFM regimen, continuous remissions are obtained without additional myeloablative chemotherapy.


Assuntos
Antibióticos Antineoplásicos/uso terapêutico , Linfoma de Burkitt/terapia , Doxorrubicina/uso terapêutico , Metotrexato/uso terapêutico , Adolescente , Adulto , Idoso , Antibióticos Antineoplásicos/administração & dosagem , Linfoma de Burkitt/mortalidade , Institutos de Câncer/estatística & dados numéricos , Doxorrubicina/administração & dosagem , Feminino , Humanos , Masculino , Metotrexato/administração & dosagem , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Noruega , Estudos Retrospectivos , Transplante de Células-Tronco , Análise de Sobrevida , Taxa de Sobrevida , Transplante Autólogo , Resultado do Tratamento
12.
Eur J Cancer ; 39(4): 488-94, 2003 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12751380

RESUMO

From 1990 to 1997, 113 eligible patients with classical osteosarcoma received neo-adjuvant chemotherapy consisting of high-dose methotrexate, cisplatin and doxorubicin. Good histological responders continued to receive the same therapy postoperatively, while poor responders received salvage therapy with an etoposide/ifosfamide combination. With a median follow-up of 83 months, the projected metastasis-free and overall survival rates at 5 years are 63 and 74%, respectively. Independent favourable prognostic factors for outcome were tumour volume < 190 ml, 24-h serum methotrexate > 4.5 microM and female gender. The etoposide/ifosfamide replacement combination did not improve outcome in the poor histological responders. In conclusion, this intensive multi-agent chemotherapy results in > 70% of patients with classical osteosarcoma surviving for 5 years. The data obtained from this non-randomised study do not support discontinuation and exchange of all drugs used preoperatively in histological poor responders. As observed in previous Scandinavian osteosarcoma studies, female gender appears to be a strong predictor of a favourable outcome.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Ósseas/tratamento farmacológico , Osteossarcoma/tratamento farmacológico , Terapia de Salvação , Adolescente , Adulto , Idoso , Neoplasias Ósseas/patologia , Neoplasias Ósseas/cirurgia , Quimioterapia Adjuvante , Criança , Pré-Escolar , Cisplatino/administração & dosagem , Doxorrubicina/administração & dosagem , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Metotrexato/administração & dosagem , Pessoa de Meia-Idade , Recidiva Local de Neoplasia , Osteossarcoma/patologia , Osteossarcoma/cirurgia , Cooperação do Paciente , Prognóstico , Análise de Sobrevida
13.
Tidsskr Nor Laegeforen ; 120(27): 3296-301, 2000 Nov 10.
Artigo em Norueguês | MEDLINE | ID: mdl-11187174

RESUMO

BACKGROUND: Physical activity has been an important influence on the evolution of our gene pool and the optimal functioning of our body. Physical activity has recently been discussed as important in relation to cancer-risk. MATERIAL AND METHODS: A total of 182 studies related to the association between physical activity and risk of cancer are included in the present study. We have used international accepted criteria in the validation of the strength of the association between a potential risk factor and cancer-risk. RESULTS: We conclude that there is convincing evidence that physical activity reduces the risk of colon cancer: the evidence is probable for breast cancer and possible for prostate, endometrial and lung cancer. Physical activity does not have any influence on rectal cancer. The evidence for all the remaining cancer sites reviewed remains insufficient to make any conclusions at this time. No increased risk due to high levels of physical activity has been observed for any cancer type. Physical activity has an independent protective effect on site-specific cancer; this effect cannot be explained by potentially confounding factors such as body mass or diet. INTERPRETATIONS: We recommend including physical activity as a modifiable risk factor in order to reduce cancer risk throughout life. More studies focusing on biological mechanisms are needed. Furthermore, improvements in the physical activity assessments used associated with site-specific cancer risk is needed. Finally, there is a need for intervention studies designed to study the carcinogenic process and the specific cancer type with biological markers and intermediate steps in the development of cancer.


Assuntos
Exercício Físico , Neoplasias/prevenção & controle , Animais , Medicina Baseada em Evidências , Feminino , Humanos , Masculino , Fatores de Risco
14.
Tidsskr Nor Laegeforen ; 120(27): 3302-4, 2000 Nov 10.
Artigo em Norueguês | MEDLINE | ID: mdl-11187175

RESUMO

BACKGROUND: In the past, patients suffering from cancer and other chronic diseases were told to avoid physical activity in order to rest and reduce discomfort. Recently, many studies have published new scientific evidence which indicates that physical activity may be an important factor in the rehabilitation for several chronic diseases. However, less is known about the importance of physical activity in the treatment and rehabilitation of cancer patients. MATERIAL AND METHODS: We performed a search on Medline and Pubmed. A total of 38 studies focusing on the importance of physical activity in the treatment and rehabilitation of cancer patients are included in the present study. RESULTS: The performed studies that have assessed the effects of physical activity on quality of life following cancer diagnosis, consistently suggest that physical activity may improve quality of life for cancer patients and influence fatigue. No information exists on whether physical activity increases survival. The limitations of these clinical studies include small sample size, lack of adjustment for possible confounders, and short intervention spans. INTERPRETATION: Physical activity is not part of the usual cancer rehabilitation program, yet clinical studies are promising and important. More studies are needed to improve our understanding of the effects and feasibility of physical activity for different groups of cancer patients. Furthermore, the importance of physical activity in relation to surgery, current conventional chemotherapy and radiation for these patients needs to be studied if we are to reduce the knowledge gap regarding the potential role of exercise in rehabilitation programmes for cancer patients compared with patients with other chronic diseases.


Assuntos
Exercício Físico , Neoplasias/terapia , Ensaios Clínicos Controlados como Assunto , Medicina Baseada em Evidências , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Masculino , Neoplasias/psicologia , Neoplasias/reabilitação , Qualidade de Vida
15.
FEBS Lett ; 427(2): 213-9, 1998 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-9607314

RESUMO

Retinol-binding protein (RBP) functions as a transporter for retinol (vitamin A) in plasma in higher eukaryotes. We have successfully expressed human RBP in Saccharomyces cerevisiae, and its secretion was found to be induced by retinol also in this lower eukaryote. Reduced induction of secretion by retinol in a temperature-sensitive sec18-1 mutant that is blocked in secretion at the restricted temperature suggests that as in mammalian cells, RBP can be released from the endoplasmic reticulum upon addition of retinol. Thus, the molecular mechanism involved in retinol-dependent secretion of RBP appears to be conserved in yeast, and this points to yeast as a putative model system for studying retinol-regulated secretion of RBP. RBP purified from yeast was found to be indistinguishable from RBP purified from human plasma in several functional assays.


Assuntos
Adenosina Trifosfatases , Proteínas de Ligação ao Retinol/metabolismo , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/metabolismo , Proteínas de Transporte Vesicular , Vitamina A/farmacologia , Fenretinida , Proteínas Fúngicas/genética , Humanos , Ligantes , Mutação , Pré-Albumina/metabolismo , Ligação Proteica , Proteínas Recombinantes de Fusão , Retinoides/farmacologia , Proteínas de Ligação ao Retinol/genética , Proteínas Plasmáticas de Ligação ao Retinol , Saccharomyces cerevisiae/genética , Vitamina A/metabolismo
16.
Proc Natl Acad Sci U S A ; 90(8): 3616-20, 1993 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-8386378

RESUMO

Rat liver stellate cells were cocultured with HepG2 human hepatoma cells, which are known to synthesize and secrete retinol-binding protein (RBP). Transfer of human RBP from HepG2 cells to stellate cells was studied by cryoimmunoelectron microscopy. In stellate cells, human RBP was found on the cell surface and within endosomes. The transfer of human RBP from HepG2 cells to stellate cells was blocked by addition of RBP antibodies to the culture medium. Very little uptake of RBP was observed when fibroblasts were cocultured with HepG2 cells. In a series of experiments, RBP was bound to its putative cell surface receptor at 4 degrees C, and the stellate cells were washed and then incubated at 37 degrees C in order to allow them to internalize a pulse of RBP. About 50% of the RBP was internalized after 6 min of incubation. The RBP-positive vesicles were initially (after 1-2 min) located close to the cell surface and later were found deeper in the cytoplasm. During the first 10 min, RBP was mainly observed in close association with membranes. After 2 hr, however, most RBP was localized in intracellular vesicles at a distance from the vesicular membranes, suggesting that RBP had been released from its receptor. Saturable binding of RBP to liver cells was demonstrated when cells were incubated with 125I-RBP at 4 degrees C and cell-associated radioactivity was determined. The calculated dissociation constant for the specific binding was 12.7 +/- 3.2 nM. A binding assay was also developed for determination of solubilized RBP receptor. Solubilized proteins from the nonparenchymal liver cells bound about 30 times more 125I-labeled RBP than did parenchymal cells (based on mass of cell protein). These data suggest that RBP mediates the paracrine transfer of retinol from hepatocytes to perisinusoidal stellate cells in liver and that stellate cells bind and internalize RBP by receptor-mediated endocytosis.


Assuntos
Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/metabolismo , Fígado/metabolismo , Proteínas de Ligação ao Retinol/metabolismo , Animais , Anticorpos , Transporte Biológico , Comunicação Celular , Células Cultivadas , Humanos , Cinética , Fígado/citologia , Fígado/ultraestrutura , Masculino , Microscopia Imunoeletrônica , Ratos , Ratos Wistar , Células Tumorais Cultivadas
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