Resveratrol (RESV), um polifenol presente em diversos compostos naturais, incluindo o vinho, tem sido associado a um efeito quimiopreventivo em diversos tipos de câncer, inclusive no câncer colorretal (CCR). Esse efeito benéfico observado em diversos estudos vem sendo atribuído, sobretudo, à sua ação anti-oxidante; muito embora o RESV também esteja envolvido em diversos outros mecanismos celulares, incluindo a apoptose. Não obstante, uma análise mais acurada sobre a potencial ação antineoplásica do RESV na promoção do CCR ainda se faz necessária. O CCR é um dos tipos de câncer mais frequentes no mundo ocidental, cuja incidência vem aumentando nos países em desenvolvimento e apesar dos esforços dos cientistas e do surgimento de novas drogas, esse tipo de câncer ainda possui altas taxas de morbidade e mortalidade. O presente estudo avaliou a potencial ação anti-neoplásica do RESV, puro e associado ao etanol (EtOH), na carcinogênese do câncer de cólon induzido por Nmetil-N\'-nitro-N-nitrosoguanidina (MNNG) em ratos através da análise de estresse oxidativo com malondialdeído (MDA) e imunoexpressão de Caspase-3 (Casp-3), gamma-H2AX (H2AX), iPCNA (PCNA) e Caveolina-1 (CAV-1). O experimento foi realizado com 48 ratos wistar, os quais foram submetidos à indução da carcinogênese (0.5 ml de solução de MNNG (5 mg/ml) e tratados com placebo, RESV (1mg/kg/dia) e RESV (1mg/kg/dia) associado com EtOH (0,377g/kg/dia). Os ratos foram subdivididos em 6 grupos: controle (G1), MNNG (G2), RESV (G3), RESV+MNNG (G4), RESV + EtOH (G5) e RESV + EtOH + MNNG (G6). Como resultado, o RESV diminuiu a produção de MDA em todos os grupos tratados, evidenciando seu efeito antioxidante sistêmico. RESV aumentou o número de corpúsculos apoptóticos e da apoptose nas criptas displásicas, levando ao aparecimento de espaços criptais acelulares (ECA) e, consequentemente, a uma redução estatisticamente significativa no número de criptas displásicas nos grupos tratados. Através da diminuição da expressão de H2AX, PCNA e CAV1, observamos que o RESV apresentou um efeito protetor no desenvolvimento de lesões pré-neoplásicas na carcinogênese induzida por MNNG. Atribuímos esse efeito à sua ação pró-apoptótica que demonstrou ser um mecanismo efetivo na carcinogênese colônica em ratos, diminuindo o número de criptas displásicas e levando a formação de ECA\'s, um fenômeno ainda não descrito na literatura. Diferente da hipótese inicial, o EtOH mitigou os efeitos pró-apoptóticos do RESV, sem, contudo, diminuir sua ação antioxidante. Assim, concluímos que a ação anti-neoplásica e quimiopreventiva do RESV é efetiva na fase de promoção da carcinogênese colônica induzida por MNNG e que a associação entre RESV + EtOh, a mesma encontrada nos vinhos, não demonstrou ser tão efetiva quanto ao RESV isolado / Resveratrol (RESV), a polyphenol present in several natural compounds, including wine, has been associated with a chemopreventive effect in different types of cancer, including colorectal cancer (CRC). This beneficial effect observed in several studies has been attributed especially due to its anti-oxidant action; more than that, RESV also is involved in several other cellular mechanisms, including apoptosis. Despite of it, a more accurate analysis of a potential anti-neoplastic action of RESV in the promotion phase of CRC is still ongoing. CRC is one of the most frequent types of cancer in the Western world, with incidence increasing in developing countries and despite the efforts of scientists and the development of new drugs, this type of cancer still has high rates of morbidity and mortality. The present study evaluated a potential anti-neoplastic action of RESV, pure and associated with ethanol, on the carcinogenesis of colorectal cancer induced by Nmethyl-N\'-nitro-N-nitrosoguanidine (MNNG) in rats through the analysis of oxidative stress with malondialdehyde (MDA) and immunoexpression of Caspase-3 (Casp-3), gamma-H2AX (H2AX), iPCNA (PCNA) and Caveolina-1 (CAV-1). Our experiments were performed with 48 wistar rats, which were subjected to carcinogenesis (0.5 ml of MNNG solution (5 mg / ml) and treated with placebo, RESV (1 mg / kg / day) and RESV (1 mg / kg / (G1), RESV + EtOH (G5), RESV + MNNG (G4), RESV + EtOH (G5) and RESV + EtOH + MNNG (G6). As a result, RESV decreases the production of MDA in all treated groups, evidencing its systemic antioxidant effect. RESV increased the number of apoptotic corpuscles and apoptosis in dysplastic crypts, leading to the appearance of acellular cryptic spaces (ACE) and, consequently, to a statistically significant reduction in the number of dysplastic crypts in the treated groups. By decreasing expression of H2AX, PCNA and CAV1, we observed that RESV had a protective effect on the development of pre-neoplastic lesions in MNNG-induced carcinogenesis. We attributed this effect to its pro-apoptotic action, which has been shown to be an effective mechanism in colonic carcinogenesis in rats, decreasing the number of dysplastic crypts and leading to the formation of ACE\'s, a phenomenon not yet described in the literature. Unlike the initial hypothesis, EtOH mitigated the pro-apoptotic effects of RESV, but did not diminish its antioxidant action. Thus, we conclude that the anti-neoplastic and chemopreventive action of RESV is effective in the promotion phase of MNNG-induced colonic carcinogenesis and that the association between RESV + EtOh, the same as that found in wines, has not been shown to be as effective as isolated RESV.

Resveratrol (RESV), um polifenol presente em diversos compostos naturais, incluindo o vinho, tem sido associado a um efeito quimiopreventivo em diversos tipos de câncer, inclusive no câncer colorretal (CCR). Esse efeito benéfico observado em diversos estudos vem sendo atribuído, sobretudo, à sua ação anti-oxidante; muito embora o RESV também esteja envolvido em diversos outros mecanismos celulares, incluindo a apoptose. Não obstante, uma análise mais acurada sobre a potencial ação antineoplásica do RESV na promoção do CCR ainda se faz necessária. O CCR é um dos tipos de câncer mais frequentes no mundo ocidental, cuja incidência vem aumentando nos países em desenvolvimento e apesar dos esforços dos cientistas e do surgimento de novas drogas, esse tipo de câncer ainda possui altas taxas de morbidade e mortalidade. O presente estudo avaliou a potencial ação anti-neoplásica do RESV, puro e associado ao etanol (EtOH), na carcinogênese do câncer de cólon induzido por Nmetil-N\'-nitro-N-nitrosoguanidina (MNNG) em ratos através da análise de estresse oxidativo com malondialdeído (MDA) e imunoexpressão de Caspase-3 (Casp-3), gamma-H2AX (H2AX), iPCNA (PCNA) e Caveolina-1 (CAV-1). O experimento foi realizado com 48 ratos wistar, os quais foram submetidos à indução da carcinogênese (0.5 ml de solução de MNNG (5 mg/ml) e tratados com placebo, RESV (1mg/kg/dia) e RESV (1mg/kg/dia) associado com EtOH (0,377g/kg/dia). Os ratos foram subdivididos em 6 grupos: controle (G1), MNNG (G2), RESV (G3), RESV+MNNG (G4), RESV + EtOH (G5) e RESV + EtOH + MNNG (G6). Como resultado, o RESV diminuiu a produção de MDA em todos os grupos tratados, evidenciando seu efeito antioxidante sistêmico. RESV aumentou o número de corpúsculos apoptóticos e da apoptose nas criptas displásicas, levando ao aparecimento de espaços criptais acelulares (ECA) e, consequentemente, a uma redução estatisticamente significativa no número de criptas displásicas nos grupos tratados. Através da diminuição da expressão de H2AX, PCNA e CAV1, observamos que o RESV apresentou um efeito protetor no desenvolvimento de lesões pré-neoplásicas na carcinogênese induzida por MNNG. Atribuímos esse efeito à sua ação pró-apoptótica que demonstrou ser um mecanismo efetivo na carcinogênese colônica em ratos, diminuindo o número de criptas displásicas e levando a formação de ECA\'s, um fenômeno ainda não descrito na literatura. Diferente da hipótese inicial, o EtOH mitigou os efeitos pró-apoptóticos do RESV, sem, contudo, diminuir sua ação antioxidante. Assim, concluímos que a ação anti-neoplásica e quimiopreventiva do RESV é efetiva na fase de promoção da carcinogênese colônica induzida por MNNG e que a associação entre RESV + EtOh, a mesma encontrada nos vinhos, não demonstrou ser tão efetiva quanto ao RESV isolado / Resveratrol (RESV), a polyphenol present in several natural compounds, including wine, has been associated with a chemopreventive effect in different types of cancer, including colorectal cancer (CRC). This beneficial effect observed in several studies has been attributed especially due to its anti-oxidant action; more than that, RESV also is involved in several other cellular mechanisms, including apoptosis. Despite of it, a more accurate analysis of a potential anti-neoplastic action of RESV in the promotion phase of CRC is still ongoing. CRC is one of the most frequent types of cancer in the Western world, with incidence increasing in developing countries and despite the efforts of scientists and the development of new drugs, this type of cancer still has high rates of morbidity and mortality. The present study evaluated a potential anti-neoplastic action of RESV, pure and associated with ethanol, on the carcinogenesis of colorectal cancer induced by Nmethyl-N\'-nitro-N-nitrosoguanidine (MNNG) in rats through the analysis of oxidative stress with malondialdehyde (MDA) and immunoexpression of Caspase-3 (Casp-3), gamma-H2AX (H2AX), iPCNA (PCNA) and Caveolina-1 (CAV-1). Our experiments were performed with 48 wistar rats, which were subjected to carcinogenesis (0.5 ml of MNNG solution (5 mg / ml) and treated with placebo, RESV (1 mg / kg / day) and RESV (1 mg / kg / (G1), RESV + EtOH (G5), RESV + MNNG (G4), RESV + EtOH (G5) and RESV + EtOH + MNNG (G6). As a result, RESV decreases the production of MDA in all treated groups, evidencing its systemic antioxidant effect. RESV increased the number of apoptotic corpuscles and apoptosis in dysplastic crypts, leading to the appearance of acellular cryptic spaces (ACE) and, consequently, to a statistically significant reduction in the number of dysplastic crypts in the treated groups. By decreasing expression of H2AX, PCNA and CAV1, we observed that RESV had a protective effect on the development of pre-neoplastic lesions in MNNG-induced carcinogenesis. We attributed this effect to its pro-apoptotic action, which has been shown to be an effective mechanism in colonic carcinogenesis in rats, decreasing the number of dysplastic crypts and leading to the formation of ACE\'s, a phenomenon not yet described in the literature. Unlike the initial hypothesis, EtOH mitigated the pro-apoptotic effects of RESV, but did not diminish its antioxidant action. Thus, we conclude that the anti-neoplastic and chemopreventive action of RESV is effective in the promotion phase of MNNG-induced colonic carcinogenesis and that the association between RESV + EtOh, the same as that found in wines, has not been shown to be as effective as isolated RESV.

Polymers of ADP-ribose (PAR) are rapidly synthesized by poly(ADPribose) polymerases (PARPs) and rapidly degraded by poly(ADP-ribose) glycohydrolase (PARG) following genotoxic stress. Since PAR metabolism plays an important role in cell fate determination following genotoxic stress, enzymes involved in PAR metabolism potentially represent promising therapeutic targets for modulating diseases of inappropriate cell proliferation or death. PARP-1 has been well validated and several PARP-1 inhibitors are currently being evaluated in clinical trials for cancer and ischemia treatment. In contrast, the biological function of PARG is still poorly understood. Due to low abundance of protein levels in mammalian cells and its unique substrate, PARG potentially represents another attractive target for pathological conditions mentioned above. PARG-Δ2,3 cells derived from homozygous PARG-Δ2,3 mice with targeted disruption of exons 2 and 3 of the PARG gene are used in this dissertation. The nuclear isoform PARG60 in PARG-Δ2,3 cells lacks the putative regulatory domain A compared to the nuclear isoform PARG110 in wild type cells. We report in this dissertation that PARG-Δ2,3 cells accumulate less PAR in spite of more rapid depletion of NAD following treatment with N-methyl- N’- Nitro-N-Nitrosoguanidine (MNNG). The estimation of PARP and PARG activity in intact cells shows increased activity of both enzymes in PARG-Δ2,3 cells following MNNG treatment, indicating the important role of domain A in the regulation of PARG and PARP activity under these conditions. Following MNNG treatment, PARG-Δ2,3 cells show reduced formation of XRCC1 foci, decreased H2AX phosphorylation, decreased DNA break intermediates during repair, and increased cell death. The altered PAR metabolism and defective cellular responses related to DNA repair in PARG-Δ2,3 cells may contribute to increased sensitivity of these cells to MNNG. Studies presented in this dissertation clearly demonstrate the important role of PARG110 in PAR metabolism and cellular responses to genotoxic stress, and thus provide supportive data for the validation of PARG as a promising potential therapeutic target.

No description available.

Experiments were carried out to determine if pretreatment of cells with N-Methyl-N'-Nitro-N-Nitrosoguanidine (a potent alkylating agent known to induce DNA repair) would affect Herpes Simplex Virus Replication. The data demonstrated a 1.5 fold increase in virus yield, a 2 fold increase in HSV specific TK activity and no change in HSV specific DNA polymerase activity in MNNG treated cultures. The effects of MNNG treatment on virus replication and enzyme expression are discussed. / Thesis / Master of Science (MSc)