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Authors
Abstract(s)
O cancro da mama continua a ser uma das principais causas de morte entre as mulheres.
Sabe-se que o tipo de dieta adotada é um dos fatores que contribui para potenciar o risco de
desenvolvimento de cancro da mama hormono-dependente, influenciando não só o
aparecimento como a progressão do mesmo.
O consumo de soja tem aumentado na alimentação ocidental. A soja é rica em
fitoestrogénios, os quais apresentam semelhanças estruturais e funcionais com os
estrogénios endógenos, permitindo-lhes interagir com os recetores de estrogénios (ER).
Desta forma, podem ter um papel como substitutos hormonais, principalmente para
mulheres em pós-menopausa.
Uma das estratégias para a terapia do cancro de mama pode passar pelo bloqueio da
atividade da aromatase, enzima responsável pelos passos limitantes na biossíntese dos
estrogénios. Desta forma, os inibidores da aromatase representam uma opção terapêutica
na prática clínica.
O objetivo deste estudo consiste em compreender a influência dos compostos estrogénicos
17ß-estradiol e de duas concentrações de extrato de soja, na adesão celular e na atividade da
aromatase de células do cancro da mama MCF-7. De acordo com os objetivos propostos, a
adesão celular foi avaliada através da determinação de proteínas totais nas amostras e a
atividade específica da aromatase foi determinada por fluorescência na presença e ausência
de um inibidor seletivo da aromatase (letrozol) com recurso ao Aromatase (CYP19A)
Activity Assay kit.
Os resultados mostram que os compostos em estudo não impedem a adesão celular à
superfície de crescimento, nomeadamente, a concentração mais elevada do extrato de soja
estudada promoveu uma maior adesão celular. Quanto à atividade específica da aromatase
verificou-se que níveis mais altos do extrato de soja não só aumentam a atividade desta
enzima em células de cancro da mama, como diminuíram a eficácia do letrozol.
De acordo com estes resultados, pode-se concluir que as doses terapêuticas do letrozol
podem não ser suficientes para inibir a aromatase na presença de soja. Desta forma, é
relevante estar alerta, pois os suplementos à base de soja podem promover a resistência à
terapêutica com letrozol.
Breast cancer remains one of the main causes of woman death. It is known that the type of diet is one of the factors to enhance the development of breast cancer risk, influencing cancer appearance but also its progression. Soy consumption has increased in Western diet. Soy is rich in phytoestrogens which have structural and functional similarities with endogenous estrogens. The phytoestrogens interact with estrogen receptors (ER) and can be used as hormone substitutes mainly by postmenopausal women. Aromatase activity inhibition can also be one of the strategies for breast cancer therapy, as this enzyme is responsible for limiting estrogens biosynthesis pathway. Thus, aromatase inhibitors are a potential therapeutic approach for clinical practice. The aim of this study is to understand the influence of estrogenic compounds 17ß-estradiol, and two concentrations of soy extract in cell adhesion and in the aromatase activity of MCF7 breast cancer cells. For these goals different procedures were addressed, the cell adhesion was studied through the determination of total proteins in the samples and the specific aromatase activity was evaluated by fluorescence in presence and absence of selective aromatase inhibitor, letrozole, using Aromatase (CYP19A) Activity Assay kit. The outcomes showed that 17ß-estradiol and soy extract does not prevent the cell adhesion. In fact, the cells treated with the highest concentration of the soy extract showed greater cell adhesion. Concerning the specific aromatase activity, it was found that higher levels of soy extract promote the activity of this enzyme in breast cancer cells. Moreover, the effect of soy extract reduced the letrozole effectiveness. The results suggest that the therapeutic doses of letrozole may not be enough to inhibit the aromatase activity in presence of soy extracts compounds. Thus, it is important to be alert because soy-based supplements can promote letrozole therapy resistance.
Breast cancer remains one of the main causes of woman death. It is known that the type of diet is one of the factors to enhance the development of breast cancer risk, influencing cancer appearance but also its progression. Soy consumption has increased in Western diet. Soy is rich in phytoestrogens which have structural and functional similarities with endogenous estrogens. The phytoestrogens interact with estrogen receptors (ER) and can be used as hormone substitutes mainly by postmenopausal women. Aromatase activity inhibition can also be one of the strategies for breast cancer therapy, as this enzyme is responsible for limiting estrogens biosynthesis pathway. Thus, aromatase inhibitors are a potential therapeutic approach for clinical practice. The aim of this study is to understand the influence of estrogenic compounds 17ß-estradiol, and two concentrations of soy extract in cell adhesion and in the aromatase activity of MCF7 breast cancer cells. For these goals different procedures were addressed, the cell adhesion was studied through the determination of total proteins in the samples and the specific aromatase activity was evaluated by fluorescence in presence and absence of selective aromatase inhibitor, letrozole, using Aromatase (CYP19A) Activity Assay kit. The outcomes showed that 17ß-estradiol and soy extract does not prevent the cell adhesion. In fact, the cells treated with the highest concentration of the soy extract showed greater cell adhesion. Concerning the specific aromatase activity, it was found that higher levels of soy extract promote the activity of this enzyme in breast cancer cells. Moreover, the effect of soy extract reduced the letrozole effectiveness. The results suggest that the therapeutic doses of letrozole may not be enough to inhibit the aromatase activity in presence of soy extracts compounds. Thus, it is important to be alert because soy-based supplements can promote letrozole therapy resistance.
Description
Keywords
17ß-Estradiol Aromatase Cancro da Mama Extrato de Soja Letrozol Mcf-7