Cepa Margarida, Correia-da-Silva Georgina, Tavares da Silva Elisiário J, Roleira Fernanda M F, Hong Yanyan, Chen Shiuan, Teixeira Natércia A
Serviço de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha, 164, 4099-030 Porto, Portugal.
Biol Chem. 2008 Sep;389(9):1183-91. doi: 10.1515/BC.2008.134.
A recent approach for treatment and prevention of estrogen-dependent breast cancer focuses on the inhibition of aromatase, the enzyme that catalyzes the final step of estrogen biosynthesis. Some synthetic steroids, such as formestane and exemestane, resembling the natural enzyme substrate androstenedione, revealed to be potent and useful aromatase inhibitors (AIs) and were approved for the treatment of estrogen-dependent breast cancer in postmenopausal women. Recently, we found that five newly synthesized steroids with chemical features in the A- and D-rings considered important for drug-receptor interaction efficiently inhibit aromatase derived from human placental microsomes. In this work, these steroids showed a similar pattern of anti-aromatase activity in several aromatase-expressing cell lines. 5alpha-androst-3-en-17-one and 3alpha,4alpha-epoxy-5alpha-androstan-17-one were revealed to be the most potent inhibitors. These compounds induced a time-dependent inhibition of aromatase, showing to be irreversible AIs. The specific interactions of these compounds with aromatase active sites were further demonstrated by site-directed mutagenesis studies and evaluated by computer-aided molecular modeling. Both compounds were able to suppress hormone-dependent proliferation of MCF-7aro cells in a dose-dependent manner. These findings are important for the elucidation of a structure-activity relationship on aromatase, which may help in the development of new AIs.
一种治疗和预防雌激素依赖性乳腺癌的新方法聚焦于抑制芳香化酶，该酶催化雌激素生物合成的最后一步。一些合成类固醇，如福美司坦和依西美坦，类似于天然酶底物雄烯二酮，被证明是有效的芳香化酶抑制剂（AIs），并被批准用于治疗绝经后妇女的雌激素依赖性乳腺癌。最近，我们发现五种新合成的类固醇，其A环和D环的化学特征被认为对药物-受体相互作用很重要，它们能有效抑制源自人胎盘微粒体的芳香化酶。在这项研究中，这些类固醇在几种表达芳香化酶的细胞系中表现出相似的抗芳香化酶活性模式。5α-雄甾-3-烯-17-酮和3α,4α-环氧-5α-雄甾烷-17-酮被证明是最有效的抑制剂。这些化合物诱导了芳香化酶的时间依赖性抑制，显示为不可逆的芳香化酶抑制剂。通过定点诱变研究进一步证明了这些化合物与芳香化酶活性位点的特异性相互作用，并通过计算机辅助分子建模进行了评估。两种化合物都能够以剂量依赖性方式抑制MCF-7aro细胞的激素依赖性增殖。这些发现对于阐明芳香化酶的构效关系很重要，这可能有助于开发新的芳香化酶抑制剂。
