Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas. Programa de Pós-graduação em Farmacologia / Made available in DSpace on 2013-07-15T23:00:01Z (GMT). No. of bitstreams: 1 212760.pdf: 3793665 bytes, checksum: 1d3548c82c1c667fb06eb82add689737 (MD5) / O tratamento in vivo em camundongos com ligantes do receptor periférico benzodiazepínico (PBR) exerceram efeito inibitório na resposta inflamatória em dois modelos de inflamação aguda. No primeiro modelo o efeito antiinflamatório em de pré-tratamento com os ligantes PBR, PK11195 1-(2-chlorophenyl)-N-methyl-N(1-methylpropyl)-3-isoquinoline carboxamide e Ro5-4864 7-chloro-5-(4-Chlorophenyl)-1,3-dihydro-1-methyl-2-H-1,4-benzodiazepin-2, mostraram que a formação do edema em resposta a carragenina (300 mg/pata) foi inibida por PK11195 e Ro5-4864, em diferentes intervalos de tempo. O estudo do tempo resposta mostrou que a melhor resposta com ambos ligantes foi ótima em animais injetados no tempo de 24h, por esta razão este tempo de pré-tratamento foi escolhido para estudo da dose resposta. A formação do edema de pata em resposta a carragenina (300 mg/pata) foi reduzida por PK11195 e Ro5-4864 em diferentes doses (0,00001-10mg/kg, i.p.) produzindo uma inibição dose dependente na formação do edema de pata em camundongos induzida pela carragenina. PK11195 e Ro5-4864 (0.1 mg/kg, i.p.) quando administrado 24 h antes da indução do edema, inibiram de forma significativa o edema de pata de camundongos induzido por vários mediadores inflamatórios. No segundo modelo o pré-tratamento com os ligantes (0.1 mg/kg, i.p.), 24 h antes da indução da pleurisia induzida pela carragenina, mostrou uma significante inibição no recrutamento das células totais e diferenciais, principalmente a custas de neutrófilos, inibindo também a liberação de Interleucina-13 (IL-13) e Interleucina-6 (IL-6) no líquido pleural

Made available in DSpace on 2014-06-11T19:33:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-06-10Bitstream added on 2014-06-13T21:06:01Z : No. of bitstreams: 1 mainenti_p_dr_sjc.pdf: 825103 bytes, checksum: cb4ac2ce4ddd387d52a086efa8ec1795 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A carcinogênese química em glândulas salivares animais não se apresenta como um modelo novo de pesquisa. O uso de DMBA em glândulas submandibulares de ratos produz carcinomas e sarcomas, associados ou não. Apesar de bem estudada a histopatologia deste tipo de carcinogênese, pouco se sabe em relação a imunoistoquímica das neoplasias. Este estudo se propõe a revisar pesquisa pregressa realizada por Mainenti (2006), na tentativa de melhor entender a formação de tumores induzidos por DMBA. O estudo original diagnosticou lesões não neoplásicas, principalmente sialadenites, e tumores como carcinomas, carcinossarcomas e um caso de sarcoma. O presente trabalho fez uso de lâminas e material de estoque em formol. Foram comparadas as lâminas originais com novas lâminas coradas em hematoxilina e eosina. Para a pesquisa de fibras colágenas utilizou-se a coloração pelo método do tricrômico de Gomori. A imunoistoquímica foi realizada utilizando os seguintes anticorpos: AE1/AE3, vimentina, α-SMA, calponina, desmina, miogenina, S-100, CerbB-2 e EMA. Certas lesões, previamente diagnosticadas como sialadenites, foram reclassificadas como carcinomas. A imunoistoquímica foi positiva para os seguintes anticorpos: AE1/AE3 para neoplasia epitelial, vimentina para tecido conjuntivo e tumores mesenquimais, α-SMA e calponina para poucas células fusiformes pleomórficas no estroma dos carcinomas e nas neoplasias mesenquimais. Concluiu-se que a imunoistoquímica revelou diferenciação muito sugestiva de miofibroblastos no estroma dos carcinomas e miofibroblastos compondo o fibrossarcoma e os carcinosarcomas. Estas células produziram colágeno revelado pelo tricrômico de Gomori. O componente epitelial neoplásico foi sugerido como derivado de células luminais. / The chemical carcinogenesis, addressed to animal salivary gland, is not a novel research. The use of DMBA in rat’s submandibular salivary gland is known to produce neoplasms like sarcomas and carcinomas either intermingled or not. Despite of the good amount of information regarding DMBA carcinogenesis histopathology in rat’s submandibular parenchyma, little is known about the immunohistochemistry in such tumors. We proposed a revision of a previous research conduced by Mainenti (2006), in attempt to better understand the neoplasm formation after DMBA. The original experiment disclosed non neoplastic lesions, mainly sialadenitis, and tumors like carcinomas, carcinosarcomas and one case of sarcoma. The present work used all the material from the first research like surgical specimens in formol and slides. We compared the previous hematoxylin and eosin slides with new ones. We also used Gomori’s trichrome in order to disclose collagen fibers. The immunohistochemistry was performed using the following antibodies: AE1/AE3, vimentin, α-SMA, calponin, desmin, myogenin, S-100, CerbB-2 and EMA. Some previous lesions, presented as benign ones, were diagnosed as carcinomas. The immunohistochemistry was positive as shown: AE1/AE3 for epithelial neoplasm, vimentin for connective tissue in mesenchymal tumors, α-SMA and calponin for scarce pleomorphic fusiform cells in the stroma of the carcinomas and in the mesenchymal neoplasms. We concluded that the immunohistochemistry strongly suggested myofibroblast differentiation in the stroma of the carcinomas and myofibroblast cells related to the fibrosarcoma and carcinosarcomas. These cells produced collagen shown after Gomori’s trichrome. The epithelial neoplasm component was suggested as derived from luminal cells.

Made available in DSpace on 2014-06-11T19:33:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-26Bitstream added on 2014-06-13T21:06:02Z : No. of bitstreams: 1 grassi_tf_dr_botfm.pdf: 2406422 bytes, checksum: 14575fe8c9692ee11119e80270b7322f (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Not available.

Made available in DSpace on 2015-04-09T12:28:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-07-30Bitstream added on 2015-04-09T12:47:47Z : No. of bitstreams: 1 000814629.pdf: 620669 bytes, checksum: 55c45e6890c124d8c36422d936178543 (MD5) / A próstata canina pode desenvolver espontaneamente lesões proliferativas, associadas com a idade, inflamação e os hormônios, tais como: a hiperplasia prostática benigna (HPB), a atrofia inflamatória proliferativa (PIA) e o carcinoma prostático (CaP). Consequentemente, o cão pode ser usado para o estudo do processo carcinogênico da próstata no homem. Alterações na expressão gênica, proteica e na função do PTEN e TP53 foram detectadas nas lesões pré-neoplásicas e neoplásicas da próstata humana. A super-expressão da oncoproteína MDM2 e a perda de marcação nuclear do receptor andrógeno (AR) foram correlacionados com progressão tumoral e ineficiência ao tratamento anti-andrógeno do CaP no homem. Neste contexto, o objetivo deste estudo foi avaliar a expressão proteica de PTEN, MDM2, p53 e AR para determinar seu papel no processo carcinogênico da próstata canina e validar os resultados obtidos pelo grupo de pesquisa com a técnica de hibridação genômica comparativa (CHG) nesses genes. Com isso, foi construído um microarranjo de tecido (TMA), com 74 amostras da glândula prostática canina, divididas em 18 HPB, 22 PIA, 19 CaP e 15 próstatas de tecido normal. A técnica de imuno-histoquímica para os anticorpos PTEN, MDM2, p53, e AR, foi realizada pelo método de peroxidase e DAB. O PTEN, p53 e AR apresentaram perda de marcação nuclear nos carcinomas prostáticos quando comparados com o tecido prostático normal. Na oncoproteína MDM2, o tecido normal obteve marcação nuclear e citoplasmática discreta enquanto no CaP, mais de 85% das amostras apresentaram super-expressão citoplasmática/nuclear. A perda de marcação nuclear do PTEN, p53 e AR, e o ganho da expressão de MDM2 também foi relatado no CaP do homem, sugerindo que existem semelhanças nas alterações moleculares da rede PTEN/MDM2/p53 e AR em ambas as espécies no processo de carcinogênese prostática. Por conseguinte, a espécie cão é um ... / The canine prostate may spontaneously develop prostatic proliferative lesions, associated with aging, inflammation and hormones, such as: benign prostatic hyperplasia (BPH), proliferative inflammatory atrophy (PIA) and prostatic carcinoma (PCa). Consequently, the dog can be used for the study of carcinogenesis process in the prostate of men. Changes in PTEN and TP53 gene and protein expression and function were detected in preneoplasic and neoplasic lesion of human prostate. MDM2 oncoprotein overexpression and loss of nuclear staining of androgen receptor (AR) were correlated with tumor progression and inefficiency antiandrogen treatment of PCa in men. In this context, the aim of this study was to evaluate PTEN, MDM2, p53 and AR protein expression to determine their role in carcinogenic process of the canine prostate. We built a tissue microarray (TMA), with 74 samples of canine prostate, divided into 18 BPH, PIA 22, 19 PCa and 15 prostates of normal tissue. The immunohistochemistry was carried for PTEN, MDM2, p53, and AR antibodies with peroxidase method and DAB. The PTEN, p53 and AR showed loss of nuclear staining in canine prostate carcinoma compared with normal prostate tissue. MDM2 oncoprotein, in normal tissue was discrete cytoplasmic and we observed nuclear staining in CaP, while more than 85% of the samples showed cytoplasmic/nuclear overexpression. The loss of nuclear staining of PTEN, p53 and AR, and the gain of MDM2 expression was also reported in human PCa, suggesting that there are similarities in the molecular alterations of PTEN/MDM2/p53 network and AR in both species in the process prostate carcinogenesis. Therefore, the dog is a potential model for the study of molecular signaling pathways as PTEN/MDM2/p53 and AR involved in human PCa

Made available in DSpace on 2015-09-17T15:24:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-07-16. Added 1 bitstream(s) on 2015-09-17T15:48:25Z : No. of bitstreams: 1 000736658.pdf: 1214770 bytes, checksum: af2c76477f3e5f2e40db225797efe558 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / The trans-resveratrol (RES) is an important substance in prevention and treatment of skin carcinogenesis. Though, the RES has low bioavailability and rapid metabolism when it administered orally, these factors could be circumvented by its dermal administration using solid lipid nanoparticles (SLNs). The aim of this study was to develop SLN with RES for use in antitumor therapy of melanoma. SLNs composed of stearic acid (SA) or polyoxyethylene stearate (40) (PS40); poloxamer 407; soy phosphatidylcholine (SPC) and the aqueous phase were made by sonication and it were added or not of 0.1% RES. The particle size, polydispersity index (PdI) and zeta potential were analyzed by dynamic light scattering (DLS). The SLNs were analyzed by field emission gun scanning electron microscope (FEG-SEM) and differential scanning calorimetry (DSC). An analytical method using HPLC-DAD was developed to quantify the RES. In vitro release and skin permeation/retention of SLN plus RES were conducted, as well as evaluation of depigmenting potency. The results concerning the average size, PdI and zeta potential of SLNs showed that formulations consisting of polyoxyethylene stearate (40) had a lower average diameter, ~20 nm, the addition of soy phosphatidylcholine promoted increases PdI and the formulations exhibited zeta potential smaller than -6mV. The DSC analysis showed no endothermic peak of the SLN with RES. Microscopic analysis suggest that material formed has nanometer distribution. The analytical method proved satisfactory in relation to RDC n° 899/2003 for RES. The formulations had release kinetics according Weibull's models and it were permeated through the skin up to 45% after 24 hours. The formulation with RES and free RES were more effective than kojic acid in tyrosinase inhibition. The results suggest that formulations had potential for use in antitumor therapy of melanoma.

Made available in DSpace on 2014-06-11T19:27:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-17Bitstream added on 2014-06-13T19:15:40Z : No. of bitstreams: 1 bidinotto_lt_me_botfm.pdf: 438545 bytes, checksum: 16013851a4d54716162eb93906126f59 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Lemongrass (Cymbopogon citratus STAPF) has been described as a potential chemopreventive agent. Thus, the present study objectives were evaluate the protective effects of oral treatment with lemongrass essential oil (LGEO) on carcinogenesis initiation phase with N-methyl-N-nitrosurea (MNU) and post-initiation carcinogenesis phase in multipleorgans model, through 7,12-dimethylbenz(a)antracene (DMBA), 1,2-dimethylhidrazine (DMH), and N-buthyl-N-(4-hidroxibuthyl)nitrosamine (BBN) administrations in Balb/C female mice. The animals were distributed into 2 experimental protocols. Experiment 1: the animals were allocated into 3 experimental groups: G1A group (negative control), G2A group (treated with LGEO 500 mg/kg b.wt., i.g., during 5 weeks and, at the end of the 3rd and 5th weeks, received one 30 mg/kg MNU i.p. application) and G3A group (treated with the LGEO vehicle, and MNU at the end of the 3rd and 5th weeks). After 4 hours of each MNU application, blood samples were collected to perform the comet assay, and, at the end of the 5th week, all animals were euthanatized and the urinary bladder, mammary glands and colon were collected for histological analysis, apoptosis and cellular proliferation counting. Experiment 2: the animals were allocated into 3 experimental groups: G1B group (positive control, DDB-treated animals), initiated with DMBA (5x1 mg i.g. applications), DMH (4x30 mg/kg s.c. applications) and BBN (8x7.5 mg/kg i.g. applications) and treated with the LGEO vehicle, and G2B and G3B groups, similarly DDB-treated, and treated with 125 mg/kg or 500 mg/kg LGEO respectively (5x/week during 6 weeks). At the end of the experimental period, all animals were euthanatized and urinary bladder, mammary glands and colon were collected for preneoplastic and neoplastic lesions analysis. The LGEO treatment reduced DNA damage in peripheral blood leukocytes as well as mammary gland cellular proliferation index.

Made available in DSpace on 2014-06-11T19:23:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-07-21Bitstream added on 2014-06-13T19:49:40Z : No. of bitstreams: 1 mainenti_p_me_sjc.pdf: 623200 bytes, checksum: d227d4d10a271c7131a651e433d811a0 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A carcinogênese consiste em um processo de alterações genéticas após contato celular com agentes físicos, químicos ou biológicos. Esta interação pode culminar em manifestações de fenótipos malignos celulares. No estudo experimental da carcinogênese em glândulas salivares animais, os autores são unânimes em apontar os hidrocarbonetos policíclicos aromáticos (HPA) como potentes agentes carcinogênicos. O 7,12 - dimetilbenzantraceno (DMBA), pertencente ao grupo dos HPA, é considerado o carcinógeno químico de eleição para a tumorigênese de glândulas salivares animais. Este trabalho visou o estudo de DMBA injetado em glândulas salivares submandibulares de ratos. Foram utilizados 28 ratos (Rattus norvegicus), com três meses de idade e peso aproximado de 300g. Os resultados revelaram, na 5ª semana, sete casos de sialadenite crônica. Na 10ª semana, um caso com atipia celular ductal, dois casos de carcinoma epidermóide e quatro de sialadenite crônica. Entre a 15ª e 20ª semanas, foram observados três casos de hiperemia, três casos de carcinoma epidermóide, um caso de sarcoma e sete casos de carcinossarcoma. A análise dos dados, em porcentagem, revelou: 3,6% de atipia celular, 3,6% de sarcoma, 10,7% de hiperemia, 17,9% de carcinoma epidermóide, 25% de carcinossarcoma e 39,4% de sialadenite crônica. Conclusão: Os dados obtidos permitiram o estudo da história natural da carcinogênese glandular por DMBA desde os processos inflamatórios iniciais até à formação de neoplasias mesenquimais, epiteliais e mistas. / The carcinogenesis consists in a process in which the direct contact between cells and some physical, chemical or biological agents results in cell malignization. In the scope of experimental salivary gland carcinogenesis there is a consensus in the use of polycyclic aromatic hydrocarbons (PAH) as carcinogens. The 7,12 - dimethylbenzanthracene (DMBA) is the most used PAH. This paper aims the investigations of the DMBA injected in rats submandibular glands. For this purpose, 28 rats (Rattus norvegicus), three months old (300 gr. weight, approximately) were used. The animals were divided into four groups of seven each. All animals were anesthetized and shaved in the neck. After antisepsis, one ventral neck incision, followed by dissection was performed in each animal. The left submandibular gland was injected with 0.1 ml of 2% DMBA in acetone. The skin was closed with 3-Ø silk suture. By the end of the 5th, 10th, 15th and 20th weeks the animals were sacrificed by lethal doses of anesthetics. The results in the 5th week presented seven cases of chronic sialadenitis. After 10 weeks one case of ductal cell atypia was evident, two cases of squamous cell carcinoma and four cases of chronic sialadenitis were also seen. Between the 15th and 20th weeks the cases were diagnosed as follows: three cases of hyperemia, three cases of squamous cell carcinoma, one case of sarcoma and seven cases of carcinosarcoma. The data analysis showed 3.6% of cellular atypia, 3.6% of sarcoma, 10.7% of hyperemia, 17.9% of squamous cell carcinoma, 25% of carcinosarcoma and 39.4% of chronic sialadenitis. Conclusion: the results allowed the investigation of the glandular carcinogenesis natural history after DMBA injection, from the beginning of inflammatory changes to the neoplastic manifestation of mesenquimal, epithelial and mixed tumours.

Made available in DSpace on 2014-06-11T19:30:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-29Bitstream added on 2014-06-13T19:00:25Z : No. of bitstreams: 1 minicucci_em_dr_botfm.pdf: 755824 bytes, checksum: 476f76bec065be2e3efb743481c7ddac (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O teste de carcinogênese experimental em língua de rato Wistar que utiliza a 4- nitroquinoline 1-oxide (4NQO) como agente cancerígeno, é um excelente modelo para se estudar o carcinoma espinocelular em todas as suas fases, além das lesões pré-neoplásicas e neoplásicas induzidas serem semelhantes àquelas da cavidade bucal de seres humanos. O objetivo do presente estudo foi investigar o papel da proteína p53 e de mutações no gene supressor tumoral TP53 exons 5 a 8 durante a carcinogênese induzida pela 4NQO em língua de rato Wistar. Para isso, 30 animais foram tratados com o cancerígeno na concentração de 50 ppm, por via oral (água de beber), e sacrificados 4, 12 ou 20 semanas após o tratamento. Dez animais foram utilizados como controle negativo. Os resultados mostraram diferenças estatisticamente significativas (p<0,05) com a aumento na expressão da proteína p53 nos grupos de animais sacrificados 12 e 20 semanas após a exposição ao cancerígeno, que também apresentaram lesões pré-neoplásicas e carcinomas espinocelulares, respectivamente. Fraca expressão da proteína p53 foi encontrada nos grupos controle e de 4 semanas de exposição ao carcinógeno. O sequenciamento genético dos exons 5 a 8 do gene TP53 não indicou a presença de mutações. Concluindo, a expressão anômala da proteína p53 nas fases intermediária e final da carcinogênese bucal não pode ser relacionada à presença de mutações nos exons 5 a 8 do respectivo gene. / The medium-term tongue carcinogenesis assay is a useful model for studying oral squamous cell carcinomas phase by phase. The aim of the present study was to investigate the expressivity of p53, as well as mutations in exons 5-8 of TP53 gene during rat tongue carcinogenesis induced by 4-nitroquinoline 1-oxide (4NQO) using immunohistochemistry and DNA sequencing, respectively. A total of 30 male Wistar rats were treated with 4- nitroquinoline 1-oxide in drinking water for 4, 12, and 20 weeks.Ten animals were used as negative control. Statistically differences (p<0.05) were found in p53 expression 12 and 20 weeks after treatment,i.e., pre-neoplastic lesions and squamous cell carcinomas, respectively. A weak immunoexpression was observed in the negative control and in ‘normal’ oral mucosa following 4 weeks after exposure to 4NQO. Regarding DNA sequencing, no mutation was found in all of the exons evaluated at all experimental periods. Taken together, our results suggest that abnormal p53 expression was present in pre-neoplastic lesions and squamous cell carcinomas of the oral cavity. However, no mutations were detected during oral cancer progression.

The prototyical tumor suppressor p53 is able to arrest cells after DNA damage or as a response to oncogene expression. The transactivation-competent (TA) isoforms of the more recently discovered p53 family member p73 also prevent tumors, but the underlying mechanisms are less well understood. The work presented here addressed this issue by using a cell culture model of tumorigenesis in which normal human diploid fibroblasts are stepwise transduced with oncogenes. Cells in pretransformed stages were shown to harbour high levels of TAp73 mRNA and protein. This positive regulation was probably a result of pRB inactivation and derepression of E2F1, a key activator of TAp73. Consequences for such cells included an increased sensitivity to the cytostatic drug adriamycin, slower proliferation and reduced survival at high cell density, as demonstrated by rescue experiments using siRNA-mediated knockdown of TAp73. In order to identify potential effector pathways, the gene expression profile of siRNA treated, matched fibroblast cell lines with high and low TAp73 levels were compared in DNA microarrays. These findings support the notion of TAp73 up-regulation as an anti-proliferative defense mechanism, blocking the progress towards full transformation. This barrier could be overcome by the introduction of a constitutively active form of Ras which caused a switch from TAp73 to oncogenic DeltaNp73 expression, presumably through the phosphatidylinositol 3-kinase (PI3K) pathway. In summary, the results presented emphasize the tumor-suppressive function of TAp73 and indicate that its downregulation is a decisive event during the transformation of human cells by oncogenic Ras mutants. / Der gut untersuchte Tumorsuppressor p53 vermag das Wachstum von Zellen nach DNA-Schädigung oder Onkogenaktivierung zu arretieren. Die transaktivierungsfähigen (TA) Isoformen von p73, eines kürzlich entdeckten Mitgliedes der p53-Familie, können ebenfalls die Tumorentstehung verhindern. Die Mechanismen sind hier aber noch sehr unvollkommen verstanden. Zu deren Untersuchung wurde in der vorliegenden Arbeit ein Zellkulturmodell der Tumorentstehung verwendet, bei dem normale humane diploide Fibroblasten schrittweise mit bestimmten Onkogenen transduziert wurden. Zellen in unvollständig transformierten Stadien hatten hohe Spiegel an TAp73-mRNA und -Protein. Diese positive Regulation war vermutlich eine Folge von pRB-Inaktivierung und der Derepression von E2F1, einem der wichtigsten Aktivatoren von TAp73. Beobachtete Konsequenzen für solche Zellen waren höhere Empfindlichkeit für Zytostatika wie Adriamycin, langsameres Wachstum und geringere Überlebensfähigkeit bei hoher Zelldichte, was durch Rescue-Experimente mit siRNA-vermitteltem TAp73-Knock down gezeigt werden konnte. Um mögliche Effektor-Signalwege zu identifizieren, wurden die Genexpressionsprofile von siRNA-behandelten Fibroblastenlinien, die sich nur im TAp73-Spiegel unterschieden, in DNA microarrays verglichen. Die Befunde daraus lassen den Schluss zu, dass die Hochregulation von TAp73 einen antiproliferativen Schutzmechanimus darstellt, der die vollständige Transformation verhindert. Diese Barriere konnte überwunden werden durch die zusätzliche Präsenz von aktiviertem Ras, das einen Wechsel der Expression von TAp73 zu der von onkogenem DeltaNp73 bewirkte. Dies ist vermutlich abhängig vom Phosphatidylinositol-Signalweg. Zusammenfassend wurde die Rolle von TAp73 als Tumorsuppressor weiter gefestigt, da die Niederregulierung des Proteins eine zentrale Rolle in der Transformation menschlicher Zellen durch onkogene Ras-Mutanten spielt.

Introdução: O carcinoma hepatocelular (CHC) é o câncer primário de fígado mais comum e está associado com a segunda menor taxa de sobrevida em 5 anos de todos os tipos de tumores. A melatonina (Mel) é uma potente molécula antioxidante que se tem mostrado benéfica em diversas situações patológicas, incluindo o CHC. Objetivo: Avaliar o efeito da Mel sobre marcadores de estresse oxidativo e angiogênicos no tecido hepático de ratos Wistar no modelo experimental de carcinogênese hepática induzida por dietilnitrosamina (DEN) associado ao acetilaminofluoreno (2-AAF). Métodos: 32 ratos machos Wistar (150g) foram divididos em 4 grupos: Controle (CO); Controle+Mel (CO+Mel); DEN e DEN+Mel. O DEN (50mg/kg) foi administrado por via intraperitoneal duas/uma vez por semana, associado a uma única dose de 2-AAF (100mg/kg). A Mel foi administrada na água de beber dos animais na concentração final de 20 mg/L e o tratamento teve início na 12ª semana perdurando até o fim das 19 semanas de experimento. O sangue dos animais foi coletado para as análises de AST, ALT, FA, γ-GT e amostras de fígado utilizadas para avaliar a lipoperoxidação (LPO), a atividade das enzimas antioxidantes (CAT, GPx e GST), os níveis de GSH e de metabólitos do óxido nítrico, a análise histógica e as proteínas envolvidas na angiogênese tumoral (VEGF, PI3K, p-Akt e eNOS). Resultados: O dano tecidual e o processo fibrogênico presentes no parênquima hepático estavam diminuídos no grupo DEN+Mel, assim como o nível de TBARS e a atividade da enzima GST quando comparados ao grupo DEN. A atividade da CAT mostrou-se aumentada no grupo DEN+Mel quando comparada ao grupo DEN. No processo angiogênio, a expressão de VEGF, PI3K, p-Akt mostrou-se diminuída no grupo DEN+Mel enquanto a expressão da eNOS apresentou-se aumentada quando comparado ao grupo DEN. Conclusão: Constatamos que a Mel foi capaz de minimizar os danos no parênquima hepático, de diminuir a LPO, modular a atividade da CAT, além de mostrar-se eficaz na redução de VEGF e da via PI3K/Akt no modelo experimental de carcinogênese hepática. / Background: Hepatocellular carcinoma (CHC) is the most common primary liver cancer and is associated with the second lowest 5-year survival rate of all tumor types. Melatonin (Mel) is a powerful antioxidant molecule that has been demonstrated to be beneficial in various pathological conditions, including HCC. Objective: The aim of this study was to evaluate the effect of Mel on oxidative stress and angiogenic markers in liver tissue of Wistar rats in the experimental model of hepatic carcinogenesis induced by diethylnitrosamine (DEN) and acetylaminofluorene (2-AAF). Methods: 32 male Wistar rats (150g) were divided into 4 groups: Control (CO); Control+Mel (CO+Mel); DEN and DEN+Mel. DEN (50mg/kg) was administered intraperitoneally once or twice a week, associated with a single dose of 2-AAF (100mg/kg). Mel was given in drinking water at the final concentration of 20 mg/L and the treatment was started at 12th week and continued until the end of the 19 weeks of experiment. Blood samples were collected for AST, ALT, AP, γ-GT and liver samples were used to evaluate lipid peroxidation (LPO), activity of antioxidant enzymes (CAT, GPx and GST), levels of GSH and nitric oxide levels, histological analysis and expression of proteins involved in tumor angiogenesis (VEGF, PI3K, p-Akt and eNOS). Results: The tissue damage and the fibrogenic process present in the hepatic parenchyma were decreased as well as the levels of TBARS and the activity of GST in the group DEN+Mel when compared to DEN group. CAT activity was increased in DEN+Mel group when we compared with DEN group. The expression of VEGF, PI3K, p-Akt was decreased in DEN+Mel group while eNOS expression was increased when compared to DEN group. Conclusion: Mel was able to minimize damage in the hepatic parenchyma, reduce LPO, modulate the activity of CAT and reduce VEGF and the PI3K/Akt pathway in a experimental model of hepatic carcinogenesis.