Navegando por Palavras-chave "Rat tongue mucosa"

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    Alkylation-induced genotoxicity as a predictor of DNA repair deficiency following experimental oral carcinogenesis
    (Springer, 2012-04-01) Carvalho, Juliana Gonçalves [UNIFESP]; Noguti, Juliana [UNIFESP]; Silva, Victor Hugo Pereira da [UNIFESP]; Dedivitis, Rogerio Aparecido; Franco, Marcello Fabiano de [UNIFESP]; Ribeiro, Daniel Araki [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Ana Costa Hosp & Santa Casa Santos
    The aim of this study was to evaluate alkylation induced genotoxicity as a result of DNA repair deficiency during 4-nitroquinoline 1-oxide (4NQO)-induced rat tongue carcinogenesis by means of single cell gel (comet) assay. Male Wistar rats were distributed into three groups of 10 animals each and treated with 50 ppm 4NQO solution through their drinking water for 4, 12, and 20 weeks. Ten animals were used as negative control. Blood samples and oral mucosa cells collected from all animals were divided into two aliquots of 20 mu L each to study basal DNA damage and DNA damage due to genotoxin sensitivity. the first aliquot was processed immediately for comet assay to assess basal DNA damage. the second aliquot was treated with a known genotoxin, methylmetanesulfonate. Significantly greater DNA damage was noticed to oral mucosa cells from 4, and 12 weeks post-treatment. Peripheral blood cells did show statistically significant differences (P < 0.05) after 20 weeks-group (squamous cell carcinoma). in conclusion, alkylation induced genotoxicity as a result of DNA repair deficiency is present in oral mucosa cells following oral experimental carcinogenesis.
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    Expression of placental glutathione S-transferase in rat tongue mucosa exposed to cigarette smoke
    (Springer, 2008-02-01) Ribeiro, Daniel Araki [UNIFESP]; Assis, Gerson Francisco de; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
    Glutatione S-transferases (GSTs) are a family of enzymes involved in detoxification of xenobiotics. Placental GST, known as GST-P, has been detected in tissues following exposure to carcinogenic agents being regarded a reliable biomarker of exposure and susceptibility in early phases of carcinogenesis. the aim of this study was to investigate the expressivity of GST-P positive foci in the rat tongue mucosa exposed to cigarette smoke by means of immunohistochemistry. A total of twelve male Wistar rats were distributed into two groups: negative control and experimental group exposed to cigarette smoke during 75 days. After experimental period, no histopathological changes in the tongue mucosa were evidenced in the negative control and the experimental group. However, a total of five GST-P positive foci were detected in two out of six animals exposed to cigarrette smoke. None control animals were noticed GST-P positive foci. These data indicate that expression of GST-P may reflect the carcinogenic effect of cigarette smoke as well as the genetic susceptibility of animals in relation to continuous carcinogens exposure.
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    Genomic instability in blood cells is able to predict the oral cancer risk: an experimental study in rats
    (Springer, 2008-10-01) Ribeiro, Daniel Araki [UNIFESP]; Grilli, Daniela Gimenes [UNIFESP]; Salvadori, Daisy Maria Favero; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
    This study was undertaken to investigate the genomic instability on blood cells during 4-nitroquinoline 1-oxide (4NQO)-induced rat tongue carcinogenesis by means of single cell gel (comet) and micronucleus assays. Male Wistar rats were distributed into three groups of 10 animals each and treated with 50 ppm 4NQO solution through their drinking water for 4, 12, and 20 weeks. Ten animals were used as negative control. Although no histopathological abnormalities were induced in the epithelium after 4 weeks of carcinogen exposure, genetic damage was found in blood cells as depicted by the mean tail moment and an increase of micronucleated polychromatic erythrocytes. After 12 and 20 weeks treatment, the same picture occurred, being the strong effect observed in the micronucleus induction. These periods correspond to pre-neoplastic lesions and well-differentiated squamous cell carcinomas, respectively. Taken together, our results support the idea that genomic instability on blood cells appears to be associated with the risk and progression of oral cancer, being a reliable tool for detecting early systemic conditions of malignancy.
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    No mutations found in exon 2 of gene p16CDKN2A during rat tongue carcinogenesis induced by 4-nitroquinoline-1-oxide
    (Springer, 2009-02-01) Minicucci, Eliana Maria; Silva, Glenda Nicioli da; Ribeiro, Daniel Araki [UNIFESP]; Favero Salvadori, Daisy Maria; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
    The medium-term tongue carcinogenesis assay is a useful model for studying oral squamous cell carcinomas phase by phase. the present study aimed to investigate mutations in exon 2 of gene p16CDKN2A during rat tongue carcinogenesis induced by 4-nitroquinoline 1-oxide (4NQO) using direct DNA-sequencing method. A total of 30 male Wistar rats were treated with 4-nitroquinoline 1-oxide (4NQO) in drinking water for 4, 12, and 20 weeks at 50 ppm dose. Ten animals were used as negative control. No histopathological changes in tongue epithelia were observed among controls or in the group treated for 4 weeks with 4NQO. Following 12-week treatment, hyperplasia and epithelial dysplasia were found in mild and moderate forms. At 20 weeks, the tongue presented moderate and/or severe oral dysplasia and squamous cell carcinoma, with squamous cell carcinoma in the majority of animals. No mutations were found in any experimental period evaluated that corresponded to normal oral mucosa, hyperplasia, dysplasia and squamous cell carcinomas. Taken together, our results suggest that p16CDKN2A mutations in exon 2 are not involved in the multistep tongue carcinogenesis of Wistar rats induced by 4NQO.
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    Placental glutathione S-transferase correlates with cellular proliferation during rat tonguie carcinogenesis induced by 4-nitroquinoline 1-oxide
    (Elsevier B.V., 2007-09-01) Silva, Renata Nunes da; Ribeiro, Daniel Araki [UNIFESP]; Salvadori, Daisy Maria Favero; Marques, Mariangela Esther Alencar; Universidade Federal de São Paulo (UNIFESP); Univ Nacl Estadual São Paulo
    Taking into consideration that glutatione S-transferase (GST) and cellular proliferation play a crucial role during carcinogenesis, the goal of this study was to investigate the expression of placental GST, called GST-P, and proliferating cellular nuclear antigen (PCNA) by means of immunohistochemistry during rat tongue carcinogenesis induced by 4-nitroquinoline 1-oxide (4NQO). This is a useful model for studying oral squamous cell carcinoma phase by phase. Male Wistar rats were distributed into three groups of 10 animals each and treated with 50 ppm 4NQO solution by drinking water for 4, 12 or 20 weeks. Ten animals were used as negative control. GST-P positive foci were detected in non-neoplastic oral cells at 4 weeks of 4NQO administration. in the same way, GST-P positive cells were detected in pre-neoplastic lesions and squamous cell carcinomas induced after 12 and 20 weeks-treatment, respectively. None of the control animals expressed GST-P positive cells. Regarding cellular proliferation, PCNA positive nuclei were higher at 12 and 20 weeks following 4NQO exposure (p < 0.05) when compared to negative control. These results suggest that the expression of GST-P is correlated with cellular proliferation, in which GST-P is associated with risk and progression of oral cancer, whereas PCNA is closely involved during neoplastic conversion. (c) 2007 Published by Elsevier GmbH.
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    The role of the TP53 gene during rat tongue carcinogenesis induced by 4-nitroquinoline 1-oxide
    (Elsevier B.V., 2011-07-01) Minicucci, Eliana Maria; Ribeiro, Daniel Araki [UNIFESP]; Silva, Glenda Nicioli da; Pardini, Maria Inês de Moura Campos; Montovani, Jair Cortez; Salvadori, Daisy Maria Favero; Universidade Federal de São Paulo (UNIFESP); São Paulo State Univ
    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 expression of p53 by immunohistochemistry and examine the DNA sequence of exons 5, 6, 7, and 8 of Tp53 for mutations during rat tongue carcinogenesis induced by 4-nitroquinoline 1-oxide (4NQO). A total of 30 male Wistar rats were treated with 4-nitroquinoline 1-oxide in their drinking water for 4, 12, and 20 weeks at a dose of 50 ppm. Ten animals were used as negative controls. No histopathological changes in the tongue epithelia were observed in the control group or in the treatment group after 4 weeks of 4NQO. Following 12 weeks of treatment, hyperplasia as well as epithelial dysplasia was found in both mild and moderate forms. At 20 weeks, moderate and/or severe oral dysplasia and squamous cell carcinoma of the tongue were found, and the majority of animals had squamous cell carcinoma. the levels of p53 protein were increased (p < 0.05) in pre-neoplastic lesions and in squamous cell carcinomas in some of the tumor cells in squamous cell carcinomas. No mutations were found in any of the exons that were evaluated after the 4-, 12-, or 20-week treatments. Taken together, our results suggest that p53 expression may be an important event in the malignant conversion, whereas Tp53 mutations are not involved in the multi-step tongue carcinogenesis of Wistar rats induced by 4NQO. (C) 2010 Elsevier GmbH. All rights reserved.
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    Survivin and inducible nitric oxide synthase production during 4NQO-induced rat tongue carcinogenesis: A possible relationship
    (Elsevier B.V., 2007-08-01) Ribeiro, Daniel Araki [UNIFESP]; Kitakawa, Darcio; Domingues, Maria Aparecida Custodio; Guimaraes Cabral, Luiz Antonio; Marques, Mariangela Esther Alencar; Salvadori, Daisy Maria Favero; Universidade Federal de São Paulo (UNIFESP); Univ Estadual Paulista
    This study was undertaken to investigate, by immunohistochermistry, the expression of survivin and inducible nitric oxide synthase during 4NQO-induced rat tongue carcinogenesis. Male Wistar rats were distributed into three groups of 10 animals each and treated with 50 ppm 4NQO solution through their drinking water for 4, 12, and 20 weeks. Ten animals were used as negative control. Although no histopathological abnormalities were induced in the epithelium after 4 weeks of carcinogen exposure, survivin and iNOS were expresssed (P < 0.05) in some cells of the 'normal' oral epithelium. in pre-neoplastic lesions at 12 weeks following carcinogen exposure, the levels of survivin and iNOS were increased (p < 0.05) when compared to negative control, being the strongest effect observed to iNOS. in well-differentiated squamous cell carcinoma induced after 20 weeks of treatment with 4NQO, survivin and iNOS were expressed in some tumor cells. Lack of immunoreactivity for both markers was observed in the negative control group. Taken together, our results support the belief that expression of survivin and iNOS are early events during malignant transformation and conversion of the oral mucosa. (c) 2007 Elsevier Inc. All rights reserved.