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Geroscience puts mechanisms of aging as a driver of the most common age-related diseases and dysfunctions. Under this perspective, addressing the basic mechanisms of aging will produce a better understanding than addressing each disease pathophysiology individually. Worldwide, despite greater functional impairment, life expectancy is higher in women than in men. Gender differences in the prevalence of multimorbidity lead mandatory to the understanding of the mechanisms underlying gender-related differences in multimorbidity patterns and disability-free life expectancy. Extensive literature suggested that inflammaging is at the crossroad of aging and age-related diseases. In this review, we highlight the main evidence on sex/gender differences in the mechanisms that foster inflammaging, i.e. the age-dependent triggering of innate immunity, modifications of adaptive immunity, and accrual of senescent cells, underpinning some biomarkers of inflammaging that show sex-related differences. In the framework of the "gender medicine perspective", we will also discuss how sex/gender differences in inflammaging can affect sex differences in COVID-19 severe outcomes.
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COVID-19 , Inflamação , Feminino , Humanos , Masculino , Fatores Sexuais , Envelhecimento/fisiologia , Imunidade InataRESUMO
Tumor-associated macrophages (TAMs) are part of the tumor microenvironment, broadly divided into M1 and M2 phenotypes. M1 macrophages, commonly identified by staining the CD11c antigen, have an antitumour immunity role, while M2 macrophages, expressing the CD163 antigen, are involved in tumor progression. Little is known about M1 and M2 phenotypes in the context of the oral tongue squamous cell carcinomas (OTSCC), a subgroup of oral cancer with peculiar clinical behavior. This study evaluated the macrophage polarization in OTSCC specimens to examine their prognostic relevance. To this end, specimens from 71 OTSCC patients graded as G1 or G3 were investigated for CD11c and CD163 expression. Immunohistochemical staining of TAMs was evaluated in tumor nests, tumor inflammation area (TIA), and tumor stroma. To analyze the expression of CD11c and CD163, the percentage of positive cells was scored as 0 (negative), 1 (<10%), 2 (11% to 50%), 3 (51% to 80%), and 4 (>80%). The staining intensity was scored as 0 (negative), 1 (weak), 2 (moderate), and 3 (intense). Higher expression of both CD163+ and CD11c+ macrophages in inflammation area positively correlated with G3 grade, both in extension and intensity. Focusing on G3 tumors, survival curves showed better disease-free survival in patients with high CD11c expression in the TIA. Presence of CD163 expression in TIA was associated with worse disease-free survival. This study evaluated, for the first time, the distribution of M1 and M2 macrophages in relation to the pathologic grade in OTSCC, highlighting the prognostic relevance of analyzing the localization of TAMs.
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Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/metabolismo , Antígeno CD11c/metabolismo , Macrófagos , Proteínas de Neoplasias/metabolismo , Receptores de Superfície Celular/metabolismo , Carcinoma de Células Escamosas de Cabeça e Pescoço , Neoplasias da Língua , Idoso , Idoso de 80 Anos ou mais , Intervalo Livre de Doença , Feminino , Humanos , Macrófagos/metabolismo , Macrófagos/patologia , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Estudos Retrospectivos , Carcinoma de Células Escamosas de Cabeça e Pescoço/metabolismo , Carcinoma de Células Escamosas de Cabeça e Pescoço/mortalidade , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologia , Taxa de Sobrevida , Neoplasias da Língua/metabolismo , Neoplasias da Língua/mortalidade , Neoplasias da Língua/patologiaRESUMO
Plasma levels of interleukin (IL)-38 were evaluated in patients with type 2 diabetes (T2DM) and healthy controls. Plasma IL-38 was higher in T2DM patients and positively related to waist/hip ratio, HbA1c, uric acid, liver function tests, triglycerides and total proteins. Patients suffering from diabetic nephropathy had the highest IL-38 levels.
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Diabetes Mellitus Tipo 2/sangue , Interleucinas/sangue , Fatores Etários , Idoso , Estudos de Casos e Controles , Feminino , Humanos , MasculinoRESUMO
Alzheimer's disease (AD), the most prevalent neurodegenerative disease in the growing population of elderly people, is still lacking minimally-invasive circulating biomarkers that could facilitate the diagnosis and the monitoring of disease progression. MicroRNAs (miRNAs) are emerging as tissue-specific and/or circulating biomarkers of several age-related diseases, but evidence on AD is still not conclusive. Since a systemic pro-inflammatory status was associated with an increased risk of AD development and progression, we focused our investigation on a subset of miRNAs modulating the inflammatory process, namely inflamma-miRNAs. The expression of inflamma-miR-17-5p, -21-5p, -126-3p, and -146a-5p was analyzed in plasma samples from 116 patients with AD compared with 41 age-matched healthy control (HC) subjects. MiR-17-5p, miR-21-5p, and miR-126-3p plasma levels were significantly increased in AD patients compared to HC. Importantly, a strong inverse relationship was observed between miR-21-5p and miR-126-3p, and the cognitive impairment, assessed by Mini-Mental State Examination (MMSE). Notably, miR-126-3p was able to discriminate between mild and severe cognitive impairment. Overall, our results reinforce the hypothesis that circulating inflamma-miRNAs could be assessed as minimally invasive tools associated with the development and progression of cognitive impairment in AD.
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PURPOSE: Prostate cancer cell motility and invasion have been linked to the up-regulated signaling of epidermal growth factor receptor and urokinase-type plasminogen activator receptor. We analyzed the expression of serum urokinase-type plasminogen activator receptor and epidermal growth factor receptor in the serum of patients with clinical suspicion of prostate cancer to evaluate the possible role as prostate cancer markers. MATERIALS AND METHODS: Serum was collected from 79 consecutive patients referred to our institution for transrectal ultrasound guided prostate biopsy. All blood samples were obtained before prostate biopsy. Total urokinase-type plasminogen activator receptor and epidermal growth factor receptor antigen in serum were measured by specific enzyme-linked immunosorbent assays. Gleason score, the number of positive cores, maximum percent of cancer and inflammation were considered on biopsy. Patients determined to have prostate adenocarcinoma underwent radical retropubic prostatectomy. Gleason score, pathological stage (extraprostatic extension), surgical margins, seminal vesicle involvement, perineural infiltration, lymphovascular invasion and cancer volume were evaluated in radical retropubic prostatectomy specimens. RESULTS: The 30 patients with prostate cancer had significantly higher levels of serum urokinase-type plasminogen activator receptor and epidermal growth factor receptor in comparison to those without prostate cancer but not significantly higher levels of prostate specific antigen. Urokinase-type plasminogen activator receptor and epidermal growth factor receptor levels closely correlated in the serum of patients with prostate cancer. In a multivariate model high serum epidermal growth factor receptor increased the probability of positive biopsies by 1.9 times. ROC analysis revealed that serum epidermal growth factor receptor had 93.3% sensitivity and 98% specificity for detecting prostate cancer at a cutoff of 67.9 ng/ml. Urokinase-type plasminogen activator receptor and epidermal growth factor receptor were significantly higher in patients with extraprostatic extension, seminal vesicle involvement and perineural infiltration in the radical retropubic prostatectomy specimens. Serum urokinase-type plasminogen activator receptor was the only independent predictive serum marker of extraprostatic extension, seminal vesicle involvement and perineural infiltration. CONCLUSIONS: The measurement of urokinase-type plasminogen activator receptor and epidermal growth factor receptor in the serum of patients with clinical suspicion of prostate cancer might provide clinically relevant information on the state of the prostate gland. Measuring serum epidermal growth factor receptor could help predict which patients have prostate cancer, while serum urokinase-type plasminogen activator receptor over expression seems to be related to tumor extraprostatic spread.
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Biomarcadores Tumorais/sangue , Receptores ErbB/sangue , Neoplasias da Próstata/sangue , Receptores de Ativador de Plasminogênio Tipo Uroquinase/sangue , Idoso , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
BACKGROUND: Oral squamous cell carcinoma (OSCC) represents the most common oral malignancy. Despite recent advances in therapy, up to 50% of the cases have relapse and/or metastasis. There is therefore a strong need for the identification of new biological markers able to predict the clinical behaviour of these lesions in order to improve quality of life and overall survival. Among tumour progression biomarkers, already known for their involvement in other neoplasia, a crucial role is ascribed to the urokinase-type plasminogen activator receptor (uPAR), which plays a multiple role in extracellular proteolysis, cell migration and tissue remodelling not only as a receptor for the zymogen pro-uPA but also as a component for cell adhesion and as a chemoattractant. The purpose of this study was to gain information on the expression of uPAR in OSCC and to verify whether this molecule can have a role as a prognostic/predictive marker for this neoplasia. METHODS: In a retrospective study, a cohort of 189 OSCC patients was investigated for uPAR expression and its cellular localization by immunohistochemistry. As standard controls, 8 normal oral mucosal tissues free of malignancy, obtained from patients with no evidence or history of oral cavity tumours, were similarly investigated. After grouping for uPAR expression, OSCCs were statistically analyzed for the variables age, gender, histological grading (G), tumour size, recurrence, TNM staging and overall survival rate. RESULTS: In our immunohistochemical study, 74 cases (39.1%) of OSCC showed a mostly cytoplasmic positivity for uPAR, whereas 115 were negative. uPAR expression correlated with tumour differentiation grade and prognosis: percentage of positive cases was the greatest in G3 (70.4%) and patients positives for uPAR expression had an expectation of life lower than those for uPAR negatives. CONCLUSION: The results obtained in this study suggest a role of uPAR as a potential biomarker useful to identify higher risk subgroups of OSCC patients.
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Carcinoma de Células Escamosas/diagnóstico , Regulação Neoplásica da Expressão Gênica , Imuno-Histoquímica/métodos , Neoplasias Bucais/diagnóstico , Prognóstico , Receptores de Superfície Celular/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma de Células Escamosas/patologia , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Bucais/patologia , Metástase Neoplásica , Receptores de Ativador de Plasminogênio Tipo Uroquinase , Estudos RetrospectivosRESUMO
BACKGROUND: A novel Cys-Ser Ret germline point mutation in a 58-year-old woman with bilateral medullary thyroid carcinoma (MTC) prompted us to perform genetic analysis of the family and evaluate the biological consequences of such a mutation. METHODS: Ret analysis by direct sequencing was performed in five family members. The biological activity and biochemical properties of the Ret- Cys515Ser mutant were analyzed in NIH-3T3 cells. RESULTS: The proband's son, age 35, had the Ret- Cys515Ser mutation and the L769 CTT/CTG exon 13 polymorphic variant, which was also found in his father. Clinical evaluation of the son also revealed bilateral multifocal microscopic MTC and papillary thyroid carcinoma (PTC). In vitro and in vivo analysis indicated ligand-independent activation of the Ret-Cys515Ser mutant due to aberrant disulfide homodimerization, increased mitogenic activity, and ability to induce anchorage-independent growth in NIH-3T3 cells in comparison to wild-type Ret, suggesting a possible role of Cys515Ser in tumor development. CONCLUSIONS: The Cys515Ser mutation adds to cysteine substitution groups that have been described in association with MTC. Our data also highlight the importance of performing a complete genetic analysis in patients who present with MTC.
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Carcinoma Medular/genética , Éxons/genética , Mutação em Linhagem Germinativa/genética , Mutação Puntual/genética , Proteínas Proto-Oncogênicas c-ret/genética , Neoplasias da Glândula Tireoide/genética , Carcinoma Medular/cirurgia , Feminino , Predisposição Genética para Doença , Humanos , Pessoa de Meia-Idade , Linhagem , Neoplasias da Glândula Tireoide/cirurgia , TireoidectomiaRESUMO
Ligand-induced membrane trafficking of the anaplastic lymphoma kinase (ALK) was studied using a chimeric receptor in which the extracellular and transmembrane domain of ALK was substituted for the corresponding regions of epidermal growth factor receptor (EGFR). Wild-type EGFR, EGFR/ALK and an EGFR/ALK kinase negative mutant were independently expressed in mouse NR6 fibroblasts. The capacity of EGFR/ALK to mediate [125I]-EGF internalization, receptor degradation and downregulation, which has never been previously described, was assayed. The rate of [125I]-EGF-induced internalization mediated by the cytoplasmic domain of ALK was reduced several fold compared with the wild-type EGFR. The low rate of EGF internalization promoted by EGFR/ALK correlated with an impaired degradation and downregulation of the receptor and indicate that ALK is not subject to traditional mechanisms used to regulate receptor tyrosine kinase function. Accordingly, ALK-activated intracellular domain does not associate in vivo with c-cbl and does not undergo ligand-mediated ubiquitination. The current study provides new insight into the function and regulation of ALK suggesting that the relative long membrane residence of activated ALK might confers a more potent and prolonged signaling activity. Indeed NR6-EGFR/ALK cells exhibited a approximately 3-fold increase in a maximal mitogenic response than NR6-EGFR.
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Endocitose , Proteínas Tirosina Quinases/biossíntese , Proteínas Recombinantes de Fusão/metabolismo , Substituição de Aminoácidos , Quinase do Linfoma Anaplásico , Animais , Arginina/metabolismo , Regulação para Baixo , Indução Enzimática , Receptores ErbB/genética , Receptores ErbB/metabolismo , Fibroblastos/metabolismo , Cinética , Ligantes , Camundongos , Mutagênese Sítio-Dirigida , Células NIH 3T3 , Ligação Proteica , Estrutura Terciária de Proteína , Proteínas Tirosina Quinases/química , Proteínas Tirosina Quinases/metabolismo , Receptores Proteína Tirosina QuinasesRESUMO
Exogenously administered ciliary neurotrophic factor (CNTF) causes weight loss in obese rodents and humans through leptin-like activation of the Jak-STAT3 signaling pathway in hypothalamic arcuate neurons. Here we report for the first time that 40min after acute systemic treatment, rat recombinant CNTF (intraperitoneal injection of 0.3mg/kg of body weight) induced nuclear translocation of the tyrosine-phosphorylated forms of STAT1 and STAT5 in the mouse median eminence and other circumventricular organs, including the vascular organ of the lamina terminalis and the subfornical organ. In the tuberal hypothalamus of treated mice, specific nuclear immunostaining for phospo-STAT1 and phospho-STAT5 was detected in ependymal cells bordering the third ventricle floor and lateral recesses, and in median eminence cells. Co-localization studies documented STAT1 and STAT5 activation in median eminence ß-tanycytes and underlying radial glia-like cells. A few astrocytes in the arcuate nucleus responded to CNTF by STAT5 activation. The vast majority of median eminence tanycytes and radial glia-like cells showing phospho-STAT1 and phospho-STAT5 immunoreactivity were also positive for phospho-STAT3. In contrast, STAT3 was the sole STAT isoform activated by CNTF in arcuate nucleus and median eminence neurons. Finally, immunohistochemical evaluation of STAT activation 20, 40, 80, and 120min from the injection demonstrated that cell activation was accompanied by c-Fos expression. Collectively, our findings show that CNTF activates STAT3, STAT1, and STAT5 in vivo. The distinctive activation pattern of these STAT isoforms in the median eminence may disclose novel targets and pathways through which CNTF regulates food intake.
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Fármacos Antiobesidade/administração & dosagem , Fármacos do Sistema Nervoso Central/administração & dosagem , Fator Neurotrófico Ciliar/administração & dosagem , Eminência Mediana/efeitos dos fármacos , Fator de Transcrição STAT1/metabolismo , Fator de Transcrição STAT5/metabolismo , Animais , Núcleo Arqueado do Hipotálamo/efeitos dos fármacos , Núcleo Arqueado do Hipotálamo/metabolismo , Western Blotting , Imuno-Histoquímica , Masculino , Eminência Mediana/citologia , Eminência Mediana/metabolismo , Camundongos , Microscopia Confocal , Neuroglia/metabolismo , Proteínas Proto-Oncogênicas c-fos/metabolismo , Fatores de TempoRESUMO
Evidence on circulating microRNAs (miRNAs) is indisputably opening a new era in systemic and tissue-specific biomarker research, highlighting new inter-cellular and inter-organ communication mechanisms. Circulating miRNAs might be active messengers eliciting a systemic response as well as non-specific "by-products" of cell activity and even of cell death; in either case they have the potential to be clinically relevant biomarkers for a number of physiopathological processes, including inflammatory responses and inflammation-related conditions. A large amount of evidence indicates that miRNAs can exert two opposite roles, activating as well as inhibiting inflammatory pathways. The inhibitory action probably relates to the need for activating anti-inflammatory mechanisms to counter potent proinflammatory signals, like the nuclear factor kappaB (NF-κB) pathway, to prevent cell and tissue destruction. MiRNA-based anti-inflammatory mechanisms may acquire a crucial role during aging, where a chronic, low-level proinflammatory status is likely sustained by the cell senescence secretome and by progressive activation of immune cells over time. This process entails age-related changes, especially in extremely old age, in those circulating miRNAs that are capable of modulating the inflammatory status (inflamma-miRs). Interestingly, a number of such circulating miRNAs seem to be promising biomarkers for the major age-related diseases that share a common chronic, low-level proinflammatory status, such as cardiovascular disease (CVD), type 2 diabetes mellitus (T2DM), Alzheimer Disease (AD), rheumatoid arthritis (RA), and cancers.
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Plasminogen activator inhibitor 1 (PAI-1) is over-expressed during ageing and it has been linked to cellular senescence. Recently, PAI-1 has been also identified in vitro as a critical downstream target of p53. TP53, the p53 gene, has a common functional polymorphism at codon 72 which influences the capability to modulate both apoptosis and cell senescence. In the attempt to demonstrate an in vivo role of p53 in the relationship between PAI-1 and age, we studied PAI-1 on 570 healthy subjects (aged from 18 to 92yrs.). PAI-1 showed significant relationship with age (r=0.12, p=0.02). Stratifying by genotype, it became evident that the association between PAI-1 and age was mainly due to Pro/Pro subjects (partial r=0.75, p<0.01). These results have been confirmed by a validation study on an independent sample population of 496 subjects (aged from 18 to 94yrs.). This is the first demonstration of an in vivo role of TP53 polymorphism in PAI-1 regulation, supporting the hypothesis that the effects of this polymorphism are age-dependent. In particular, our results indicate that Pro/Pro genotype plays a pivotal role in determining PAI-1 levels in aged subjects, while in Arg carriers PAI-1 levels are associated to the known insulin related determinants.
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Envelhecimento , Genes p53 , Genótipo , Inibidor 1 de Ativador de Plasminogênio/sangue , Inibidor 1 de Ativador de Plasminogênio/genética , Polimorfismo Genético , Prolina/genética , Proteína Supressora de Tumor p53/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Códon , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Oncogenic rearrangements of the tyrosine kinase receptor anaplastic lymphoma kinase (ALK), most commonly represented by the nucleophosmin/ALK fusion protein (NPM/ALK), are involved in the pathogenesis of anaplastic large-cell lymphomas (ALCLs). In an effort to identify new intracellular transducers operative in ALK-positive malignancies, we have investigated the potential involvement of diacylglycerol kinase (DGK). Here we show that alphaDGK is constitutively activated in the NPM/ALK-positive ALCL-derived cell line Karpas 299 and in NPM/ALK-infected 32D hematopoietic cells. These results were further validated in fibroblastic NIH-3T3 cells expressing a previously described chimeric epidermal growth factor receptor (EGFR)/ALK molecule that allows dissection of ALK enzymatic function under conditions of controlled ligand-induced activation. In this cell system, we also show that ALK-mediated alphaDGK activation is dependent on p60src tyrosine kinase, with which alphaDGK forms a complex. The specific inhibition of alphaDGK, obtained by cell treatment with R59949, significantly reduced cellular growth in all cell lines. This result was further confirmed in Karpas 299 cells following specific down-regulation of alphaDGK by RNA interference. Overall, our data indicate that alphaDGK activation is involved in the control of ALK-mediated mitogenic properties.
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Proliferação de Células , Diacilglicerol Quinase/metabolismo , Linfoma Difuso de Grandes Células B/etiologia , Proteínas Tirosina Quinases/fisiologia , Quinase do Linfoma Anaplásico , Linhagem Celular , Ativação Enzimática , Inibidores Enzimáticos/farmacologia , Humanos , Linfoma Difuso de Grandes Células B/patologia , Proteína Oncogênica pp60(v-src)/metabolismo , Proteínas Tirosina Quinases/antagonistas & inibidores , Proteínas Tirosina Quinases/metabolismo , RNA Interferente Pequeno/farmacologia , Receptores Proteína Tirosina Quinases , Regulação para CimaRESUMO
OBJECTIVE: Several splice variants (SVs) of GHRH receptor (GHRH-R) have been identified in various human cancers through which GHRH antagonists may exert their IGF-II-mediated antiproliferative action. Because the overexpression of the IGF-II gene is a frequent feature of adrenal carcinoma, we searched for the presence of GHRH-R SVs in these tumours. METHODS AND RESULTS: The expression of GHRH-R SVs was assessed by nested PCR in 45 human adrenocortical tumours. We have amplified 720-, 566- and 335-bp PCR products only in carcinomas. Their sequence revealed three open reading frames, corresponding to SV1, SV2 and SV4 of GHRH-R. SV2 was detected in five of 24 cancers examined, whereas the incidence of SV1 and SV4 was lower. Their simultaneous expression was observed in one carcinoma. No PCR products for SV3 or wild-type GHRH-R were found in carcinomas; mRNA for wild-type GHRH-R or SVs of GHRH-R were not observed either in adenomas or in normal adrenal or in NCI-H295R cells. Interestingly, all carcinomas which expressed SVs were also positive for the presence of GHRH mRNA. CONCLUSION: This is the first time that the expression of splice variants of GHRH-R has been demonstrated in human adrenal carcinoma. This study raises the possibility that splice variants might play a role in adrenal carcinogenesis and might offer the possibility for new therapeutic strategies at least in a subgroup of adrenal carcinomas.
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Neoplasias do Córtex Suprarrenal/genética , Processamento Alternativo , Carcinoma/genética , Polimorfismo Genético , RNA Mensageiro/análise , Receptores de Neuropeptídeos/genética , Receptores de Hormônios Reguladores de Hormônio Hipofisário/genética , Adenoma/genética , Adenoma/metabolismo , Adolescente , Neoplasias do Córtex Suprarrenal/metabolismo , Adulto , Idoso , Sequência de Bases , Carcinoma/metabolismo , Linhagem Celular Tumoral , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Receptores de Neuropeptídeos/metabolismo , Receptores de Hormônios Reguladores de Hormônio Hipofisário/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNA , Células Tumorais CultivadasRESUMO
OBJECTIVE: To investigate urokinase plasminogen activator receptor (uPAR) expression in urothelial papilloma and in noninvasive and early invasive papillary carcinoma. STUDY DESIGN: The study included 40 cases of papillary neoplasia of the urinary bladder subdivided into 10 cases of urothelial papilloma (UP); 10 of papillary carcinoma, grade 1; 10, grade 2 (G2); and 10, grade 3 (G3). Invasion of the subepithelial connective tissue was present in 5 cases of G2 and 7 cases of G3. According to the 2002 revision of the TNM system, these cases were defined as T1 and the others as Ta. uPAR expression was evaluated with an immunohistochemical technique in 5-microns-thick tissue sections. RESULTS: Difference in the distribution of positive cases in the 4 groups were statistically significant and greatest in G3. Statistically significant differences were also observed between Ta and T1 cases in terms of uPAR intensity. CONCLUSION: Detection of immunoreactivity for uPAR was associated with high grade UP carcinomas. These data indicate that uPAR is potentially an important prognostic factor in bladder carcinoma.
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Carcinoma Papilar/metabolismo , Receptores de Superfície Celular/metabolismo , Neoplasias da Bexiga Urinária/metabolismo , Biomarcadores Tumorais/análise , Biomarcadores Tumorais/metabolismo , Carcinoma Papilar/patologia , Interpretação Estatística de Dados , Humanos , Imuno-Histoquímica , Invasividade Neoplásica , Estadiamento de Neoplasias , Receptores de Superfície Celular/análise , Receptores de Ativador de Plasminogênio Tipo Uroquinase , Neoplasias da Bexiga Urinária/patologiaRESUMO
Oncogenic rearrangements of the anaplastic lymphoma kinase (ALK) gene, encoding a receptor type tyrosine kinase, are frequently associated with anaplastic large cell lymphomas. Such rearrangements juxtapose the intracellular domain of ALK to 5'-end sequences belonging to different genes and create transforming fusion proteins. To understand how the oncogenic versions of ALK contribute to lymphomagenesis, it is important to analyze the biological effects and the biochemical properties of this receptor under controlled conditions of activation. To this aim, we constructed chimeric receptor molecules in which the extracellular domain of the ALK kinase is replaced by the extracellular, ligand-binding domain of the epidermal growth factor receptor (EGFR). Upon transfection in NIH 3T3 fibroblasts, the EGFR/ALK chimera was correctly synthesized and transported to the cell surface, where it was fully functional in forming high versus low affinity EGF-binding sites and transducing an EGF-dependent signal intracellularly. Overexpression of the EGFR/ALK chimera in NIH 3T3 was sufficient to induce the malignant phenotype; the appearance of the transformed phenotype was, however, conditionally dependent on the administration of EGF. Moreover, the EGFR/ALK chimera was significantly more active in inducing transformation and DNA synthesis than the wild type EGFR when either was expressed at similar levels in NIH 3T3 cells. Comparative analysis of the biochemical pathways implicated in the transduction of mitogenic signals did not show any increased ability of the EGFR/ALK to phosphorylate PLC-gamma and MAPK compared with the EGFR. On the contrary, EGFR/ALK showed to have a consistently greater effect on phosphatidylinositol 3-kinase activity compared with the EGFR, indicating that this enzyme plays a major role in mediating the mitogenic effects of ALK in NIH 3T3 cells.