Wnt signalling and cancer stem cells

[Abstract] Intracellular signalling mediated by secreted Wnt proteins is essential for the establishment of cell fates and proper tissue patterning during embryo development and for the regulation of tissue homeostasis and stem cell function in adult tissues. Aberrant activation of Wnt signalling pathways has been directly linked to the genesis of different tumours. Here, the components and molecular mechanisms implicated in the transduction of Wnt signal, along with important results supporting a central role for this signalling pathway in stem cell function regulation and carcinogenesis will be briefly reviewed.Ministerio de Ciencia e Innovación; SAF2008-0060

Efeito da suplementação com pupunha como fonte de vitamina A em dieta: estudo em ratos Effect of supplementation with peach palm as source of vitamin A: study with rats

Foi estudado o efeito da suplementação com pupunha (Bactris gasipaes H.B.K.), polpa cozida e transformada em farinha, como fonte de vitamina A, em dieta regional de Manaus, AM,Brasil, por meio do ensaio biológico com ratos. A metodologia utilizada foi da depleção dos animais em zinco e vitamina A, seguida da repleção com a dieta regional (DR), DR + pupunha, DR + vitamina A e dieta controle (DC). A dieta foi elaborada para famílias com rendimentos inferiores a dois salários-mínimos. Foram utilizadas ratas albinas adultas pós-parto, cada qual com 6 filhotes machos, que receberam ração à base de caseína lavada com EDTA a 1%, sem adição de Zn e vitamina A, por 25 dias, com a finalidade de obtenção de animais recém-desmamados deficientes nestes dois nutrientes. O período de repleção dos animais, recém-desmamados, foi de 30 dias e o delineamento foi inteiramente casualizado com 4 tratamentos de 8 animais cada. A suplementação efetuada seguiu as recomendações do "Committee on Laboratory Animal Diets". Os parâmetros empregados para a avaliação da utilização de vitamina A foram as concentrações de vitamina A no fígado e plasma e o crescimento dos animais. Ao final do experimento, observou-se que os animais que consumiram a ração à base da dieta regional de Manaus, suplementada com pupunha e vitamina A, apresentaram, respectivamente, concentração significativamente maior de vitamina A no fígado, 43,3 ± 6,5 µg/g e 42,0 ± 4,3 µg/g em relação à dieta regional, 5,5 ± 1,1 µg/g (p<0,05). A quantidade de zinco presente na dieta regional de Manaus, 10,7 mg diários, foi biodisponível quando avaliada pela concentração de zinco nos fêmures. Os resultados sugerem que existe necessidade de suplementação da dieta regional de Manaus com vitamina A para a manutenção das reservas hepáticas, podendo, para tanto, ser utilizada a fonte natural da pupunha.<br>The effect of supplementation with peach palm (Bactris gasipaes H.B.K.), as an alternative source of vit. A, in the regional diet of Manaus, AM, Brazil, in which the pulp was cooked and transformed into flour, was studied. The biological trial involved rats which were depleted in zinc and vitamin A, followed by repletion using the regional diet (RD), RD plus peach palm and RD plus vitamin A. The parameters used to determine the utilization of vitamin A were the vitamin A concentrations in the liver and plasma, and the growth of the animals. The diet was prepared according to the data of Shrimpton and Giugliano for families earning less than two legal minimum salaries. Adult post-partum rats were used, with six male pups each, which received a diet based on casein washed with 1% EDTA, without the addition of zinc or vitamin A for a period of 25 days, for the purpose of obtaining newly-weaned animals which were deficient in Zn and Vit.A. A control group received a diet also based on casein washed with 1% EDTA, but with all the nutrients in the quantities suggested by the Committee on Laboratory Animal Diets. The repletion period of the newly-weaned rats was of 30 days and the experimental design was entirely randomized with four groups of eight rats each. The diet supplementation followed the recommendations of the Committee on Laboratory Animal Diets. At the end of the experiment, it was observed that rats which consumed the diet based on the regional diet of Manaus supplemented with either peach palm or vitamin A showed a significantly greater concentration of vitamin A in the liver, 43.3 ± 6.5 µg/g, 42.0 ± 4.3 µg/g, respectively in relation to the regional diet, 5.5 ± 1.1 µg/g (p<0.05). The amount of zinc present in the regional diet, 10.7 mg per day, was bioavailable as determined by the concentration of zinc in the femurs. The results suggest that the regional diet of Manaus needs to be supplemented with vitamin A to maintain the hepatic reserves, and that such suplementation can be accomplished with peach palm, an abundant local commodity