RESUMO
It is well known that glucocorticoids induce peripheral insulin resistance in rodents and humans. Here, we investigated the structural and ultrastructural modifications, as well as the proteins involved in beta-cell function and proliferation, in islets from insulin-resistant rats. Adult male Wistar rats were made insulin resistant by daily administration of dexamethasone (DEX; 1mg/kg, i.p.) for five consecutive days, whilst control (CTL) rats received saline alone. Structure analyses showed a marked hypertrophy of DEX islets with an increase of 1.7-fold in islet mass and of 1.6-fold in islet density compared with CTL islets (P < 0.05). Ultrastructural evaluation of islets revealed an increased amount of secreting organelles, such as endoplasmic reticulum and Golgi apparatus in DEX islets. Mitotic figures were observed in DEX islets at structural and ultrastructural levels. Beta-cell proliferation, evaluated at the immunohistochemical level using anti-PCNA (proliferating cell nuclear antigen), showed an increase in pancreatic beta-cell proliferation of 6.4-fold in DEX islets compared with CTL islets (P < 0.0001). Increases in insulin receptor substrate-2 (IRS-2), phosphorylated-serine-threonine kinase AKT (p-AKT), cyclin D(2) and a decrease in retinoblastoma protein (pRb) levels were observed in DEX islets compared with CTL islets (P < 0.05). Therefore, during the development of insulin resistance, the endocrine pancreas adapts itself increasing beta-cell mass and proliferation, resulting in an amelioration of the functions. The potential mechanisms that underlie these events involve the activation of the IRS-2/AKT pathway and activation of the cell cycle, mediated by cyclin D(2). These adaptations permit the maintenance of glycaemia at near-physiological ranges.
Assuntos
Ciclinas/análise , Resistência à Insulina , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Ilhotas Pancreáticas/patologia , Fosfoproteínas/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais/fisiologia , Animais , Proteínas de Ciclo Celular/análise , Proliferação de Células , Ciclina D2 , Ciclinas/metabolismo , Dexametasona , Glucagon/análise , Técnicas Imunoenzimáticas , Insulina/análise , Proteínas Substratos do Receptor de Insulina , Ilhotas Pancreáticas/metabolismo , Masculino , Microscopia Eletrônica de Transmissão , Modelos Animais , Ratos , Ratos WistarRESUMO
Overexpression of the HER2/NEU gene is associated with aggressive behavior and poor prognosis in breast cancer, making the Her2/neu protein a directed-therapy target. Tumors of two Puerto Rican (PR) patients overexpressed Her2/neu and resulting partial clinical responses motivated us to compare Her2/neu expression in PR (n = 101) and Caucasian non-Hispanic (n = 95) patients. Immunohistochemistry of tumors showed overexpression of p-Stat3, Cyclin D1, and Her2/neu, compared to non-neoplastic mucosa. Her2/neu and EGF-R protein levels were statistically significantly different with higher levels of both proteins in the PR group. Importantly, Her2/neu expression was strong and diffuse in tumors with signet-ring morphology, while other histo-pathological subtypes showed higher intra-tumoral Her2/neu heterogeneity than typically observed in breast cancer. Targeted therapies in gastric cancer directed at EGF-R and Hers-2/neu pathways warrant further investigation. These therapies may be especially effective in PR patients and in patients with signet-ring cell morphologies with a dismal prognosis.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/análise , Adenocarcinoma , Antineoplásicos/uso terapêutico , Carcinoma de Células em Anel de Sinete , Hispânico ou Latino , Seleção de Pacientes , Neoplasias Gástricas , População Branca , Adenocarcinoma/química , Adenocarcinoma/etnologia , Adenocarcinoma/patologia , Adenocarcinoma/terapia , Adulto , Carcinoma de Células em Anel de Sinete/química , Carcinoma de Células em Anel de Sinete/tratamento farmacológico , Carcinoma de Células em Anel de Sinete/etnologia , Carcinoma de Células em Anel de Sinete/patologia , Ciclina D , Ciclinas/análise , Receptores ErbB/análise , Feminino , Florida , Humanos , Imuno-Histoquímica , Masculino , Porto Rico , Receptor ErbB-2/análise , Estudos Retrospectivos , Fator de Transcrição STAT3/análise , Neoplasias Gástricas/química , Neoplasias Gástricas/etnologia , Neoplasias Gástricas/patologia , Neoplasias Gástricas/terapiaRESUMO
OBJECTIVE: Although the genetic program for reinitiating DNA synthesis exists in post-mitotic cardiomyocytes, and it was reported that in human acute myocardial infarction (AMI) a significant proportion of myocytes enter mitosis, the rule is that the lost tissue is replaced by a collagen scar. The purpose of this study was to search for the basis of this discordance in order to devise future strategies to induce division of myocytes into daughter cells that may replace the lost tissue with contractile cells. METHODS: In 15 human hearts with 1- to 21-day-old infarcts, the expression of the cell cycle proteins Ki67 antigen, cyclins D, A, and B1, the presence of mitotic bodies, and the ploidy status were investigated with immunoenzymatic methods, light and laser confocal microscopy, and densitometry in the myocytes surrounding the infarct area. RESULTS: In 7- to 13-day-old infarcts, 11.61+/-6.94% of the myocytes presented Ki67+ nuclei, and a lower proportion presented cyclins D, A, and B. At earlier and later times, the proportion of Ki67+ myocytes was significantly lower. Although under confocal microscopy and fluorescent labels, some of the Ki67+ myocytes appeared to be in different stages of mitosis, with Nomarski optics and hematoxylin counterstaining, the condensed chromosomes, although arranged in metaphase and anaphase plates or split in sister chromatids, were always located within a preserved nuclear envelope, indicating the presence of endomitosis. Conventional mitosis was exceptionally observed. In the 14- and 21-day-old infarcts, the ploidy of the myocytes adjacent to the infarct was significantly higher than in distant zones. CONCLUSION: These observations indicate that in human infarcts, entrance of cardiomyocytes into the cell cycle is transient and that endomitosis, leading to polyploidy, rather than mitosis, leading to karyokinesis, is the final fate of cycling cells. Both observations may account for the discordance between the regenerative ability of myocytes and the lack of an efficient reparative process in human AMI.
Assuntos
Proteínas de Ciclo Celular/análise , Infarto do Miocárdio/metabolismo , Miócitos Cardíacos/química , Adulto , Idoso , Biomarcadores/análise , Estudos de Casos e Controles , Ciclina A/análise , Ciclina B/análise , Ciclina B1 , Ciclina D , Ciclinas/análise , Feminino , Humanos , Antígeno Ki-67/análise , Masculino , Microscopia Confocal , Microscopia de Fluorescência , Pessoa de Meia-Idade , Mitose , Infarto do Miocárdio/genética , Infarto do Miocárdio/patologia , Miócitos Cardíacos/patologia , PoliploidiaRESUMO
BACKGROUND: Because biological behavior in lung tumors with neuroendocrine differentiation is highly dependent on cell death (apoptosis) and angiogenesis, p21(waf1/cip1) and microvessel density have been targeted as potentially useful tumor markers. We sought to validate the importance of p21(waf1/cip1) and microvessel density and study their interrelationship, analyzing clinical factors, subclassifications, and tumor and stromal markers. METHODS: We examined p21(waf1/cip1) and other markers in tissue from 61 patients with surgically excised large cell carcinomas. The amount of tumor staining for p21(waf1/cip1) and microvessel density was evaluated by immunohistochemistry and morphometry. The study outcome was survival time until death from recurrent lung cancer. RESULTS: Multivariate Cox model analysis demonstrated that after surgical excision, histologic subtypes were significantly related to survival time (p = 0.02), but quantitative staining of the tumor for p21(waf1/cip1) and microvessel density added prognostic information and these variables were more strongly prognostic than histologic subtype (p = 0.00). Cut points at the median staining of 3.5% and 3.0% for p21(waf1/cip1) and microvessel density, respectively, divided patients into two groups with distinctive survival times. Patients with p21(waf1/cip1) staining of more than 3.5% and microvessel density staining of more than 3.0% had a median survival time of 14 months. CONCLUSIONS: Tumor staining for p21(waf1/cip1) and microvessel density in resected large cell carcinomas and certain other types of lung tumors was strongly related to survival. Patients with more than 3.0% staining in their tumors were at high risk of death from lung cancer and may be an appropriate target for prospective studies of adjuvant chemotherapy after surgical resection.
Assuntos
Carcinoma de Células Grandes/patologia , Carcinoma Neuroendócrino/patologia , Neoplasias Pulmonares/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma de Células Grandes/química , Carcinoma de Células Grandes/mortalidade , Carcinoma Neuroendócrino/química , Carcinoma Neuroendócrino/mortalidade , Inibidor de Quinase Dependente de Ciclina p21 , Ciclinas/análise , Ciclo-Oxigenase 2 , Feminino , Humanos , Imuno-Histoquímica , Isoenzimas/análise , Neoplasias Pulmonares/química , Neoplasias Pulmonares/mortalidade , Masculino , Metaloproteinase 9 da Matriz/análise , Proteínas de Membrana , Pessoa de Meia-Idade , Modelos de Riscos Proporcionais , Prostaglandina-Endoperóxido Sintases/análise , Estudos Retrospectivos , Taxa de Sobrevida , Proteína Supressora de Tumor p53/análiseRESUMO
This study links the tumor inhibitory effect of anti-progestins RU486 and ZK98299 to the expression of cell cycle proteins. Medroxyprogesterone acetate-induced ductal mammary adenocarcinoma-bearing female BALB/c mice were treated daily either with RU486 or ZK98299, observing tumor growth retardation. p21 increased after 24 h treatment, peaked at day 4 and returned to control levels at day 7. Cyclin D1, cyclin E, CDK2 and CDK4, did not change during treatment. These results suggest that p21 might play a role in early inhibitory stages of tumor growth induced by RU486 and ZK98299.