Assuntos
Fator Estimulador de Colônias de Granulócitos e Macrófagos/metabolismo , Células-Tronco Hematopoéticas/patologia , Receptores de Hialuronatos/fisiologia , Mutação/genética , Transtornos Mieloproliferativos/mortalidade , Leucemia-Linfoma Linfoblástico de Células T Precursoras/mortalidade , Proteínas Proto-Oncogênicas p21(ras)/fisiologia , Animais , Transplante de Medula Óssea , Células-Tronco Hematopoéticas/metabolismo , Integrases/metabolismo , Camundongos , Camundongos Knockout , Transtornos Mieloproliferativos/genética , Transtornos Mieloproliferativos/metabolismo , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/metabolismo , Transdução de Sinais , Taxa de SobrevidaRESUMO
Cancers of the colon and breast are two of the most prevalent cancers in developed countries. The present experiments were conducted to determine the influence of several dietary doses of grape seed proanthocyanidins on 7,12-dimethylbenz[a]anthracene-induced mammary tumorigenesis and azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) formation in a dual-organ tumor model. In addition, the effects of the grape seed proanthocyanidins on liver cytochrome P-450 1A and 2E1 and glutathione S-transferase activities and on colonic ornithine decarboxylase activity were examined to determine possible mechanisms of action. Feeding female rats diets containing 0.1-1.0% grape seed proanthocyanidins was associated with a significant 72-88% inhibition of AOM-induced aberrant crypt foci formation and a 20-56% inhibition of ornithine decarboxylase activity in the distal third of the colon. Feeding the grape proanthocyanidins resulted in no significant effect on the activity of liver cytochrome P-450 2E1. There was no effect of feeding these doses of proanthocyanidins on 7,12-dimethylbenz[a]anthracene-induced rat mammary tumorigenesis. This lack of action on mammary tumorigenesis in part may be due to lack of effect of dietary proanthocyanidins on the liver carcinogen-metabolizing enzymes cytochrome P-450 1A and glutathione S-transferase. These results indicate that grape polyphenolics warrant further evaluation as potential colon cancer chemopreventive agents.
Assuntos
Antocianinas/farmacologia , Neoplasias do Colo/patologia , Neoplasias Mamárias Experimentais/patologia , Lesões Pré-Cancerosas/patologia , Proantocianidinas , Sementes/química , Vitis/química , 9,10-Dimetil-1,2-benzantraceno , Animais , Antocianinas/uso terapêutico , Azoximetano , Carcinógenos , Neoplasias do Colo/induzido quimicamente , Neoplasias do Colo/prevenção & controle , Citocromo P-450 CYP2E1/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Feminino , Glutationa Transferase/metabolismo , Fígado/enzimologia , Neoplasias Mamárias Experimentais/induzido quimicamente , Neoplasias Mamárias Experimentais/prevenção & controle , Ornitina Descarboxilase/metabolismo , Lesões Pré-Cancerosas/induzido quimicamente , Lesões Pré-Cancerosas/prevenção & controle , Ratos , Ratos Sprague-DawleyRESUMO
Ornithine decarboxylase is the rate-limiting enzyme in the biosynthesis of polyamines, which are believed to play an essential role in diverse biological processes including cell proliferation and differentiation. We have previously reported [J. Bomser, K. Singletary, M. Wallig, M. Smith, Inhibition of TPA-induced tumor promotion in CD-1 mouse epidermis by a polyphenolic fraction from grape seeds, Cancer Letters 135 (1999) 151-157] that pre-application of a grape polyphenolic fraction (GPF) to mouse skin epidermis inhibits 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ornithine decarboxylase (ODC) activity, as well as 7, 12-dimethylbenz[a]anthracene (DMBA)-initiated, TPA-promoted mouse skin tumorigenesis. The present studies were designed to further characterize the effect of time and dose of application of GPF on TPA-induced ODC activity and protein expression, and on protein kinase C activity in mouse skin epidermis. In addition, the effect of GPF on ODC kinetics in vitro was examined. Application of 5, 10, and 20 mg of GPF 20 min prior to treatment with TPA resulted in a significant decrease in epidermal ODC activity of 54, 53, 90%, respectively, compared with controls. Yet, ODC protein levels (Western blot) in the 10 and 20 mg GPF groups were significantly increased by 1.8 and 1.9-fold, respectively, compared with controls. A similar response was observed with the ODC inhibitor 2-difluoromethylornithine (DFMO), which served as a positive control. Application of grape polyphenolics (20 mg) at 60 and 30 min prior to treatment with TPA inhibited ODC activity by 62 and 68%, respectively, compared with controls (P<0.05). In contrast, application of grape polyphenolics (20 mg) at 60, 120 and 240 min after treatment with TPA resulted in no significant changes in ODC activity. A similar increase in epidermal ODC protein was observed in these GPF-treated animals, similar to that observed when GPF application preceded TPA. When applied to mouse skin prior to TPA, GPF was associated with a decrease in subsequent PKC activity compared with controls at 10 and 30 min following TPA treatment. The GPF-associated decrease in PKC activity preceded the decrease in ODC activity. In a separate in vitro study, kinetic analyses indicated that GPF is a competitive inhibitor of ODC activity. Collectively these data suggest that the grape polyphenolic fraction is effective as an inhibitor of ODC activity when applied before TPA, and that the magnitude of inhibition is independent of epidermal ODC protein content. In addition, GPF is a competitive inhibitor of ODC activity in vitro. The decrease in TPA-induced ODC activity due to GPF treatment is preceded by an inhibition of TPA-induced PKC activity. Thus, the polyphenolic fraction from grapes warrants further examination as a skin cancer chemopreventive agent that interferes with cellular events associated with TPA promotion.
