Inhibition of c-src transcription by mithramycin:: Structure-activity relationships of biosynthetically produced mithramycin analogues using the c-src promoter as target
Inhibition of c-src transcription by mithramycin:: Structure-activity relationships of biosynthetically produced mithramycin analogues using the c-src promoter as target
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DOI：
10.1021/bi034091z
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发表时间：
2003-07-15
期刊：
影响因子：
2.9
通讯作者：
Rohr, J
中科院分区：
文献类型：
--
作者：
Remsing, LL;Bahadori, HR;Rohr, J
金黄色抗癌抗生素米曲霉素(MTM)通过使富含GC的DNA交联，从而阻断Sp家族转录因子与基因调控元件的结合，从而抑制肿瘤生长和骨吸收。C-src基因的转录受Sp因子与其启动子中的特定元件结合的调控，c-src基因与许多人类癌症有关，是破骨细胞依赖的骨吸收所必需的。因此，该基因代表了一个重要的抗癌靶点和潜在的先导靶点，通过该靶点，MTM展示了其迄今尚未确定的抗破骨细胞性骨吸收的作用。在这里，我们使用DNA结合研究、启动子报告分析和RT-PCR证明，MTM抑制Sp与c-src启动子区域的结合，从而减少其在人类癌细胞中的表达。此外，通过组合生物合成产生的米特拉霉素类似物，即普里特拉霉素13、米特拉霉素SK、7-去甲基米特拉霉素、4E-酮基米特拉霉素和4C-酮去甲氧基米特拉霉素，与MTM比较了它们阻断Sp与c-src启动子结合的能力。虽然大多数受试化合物失去了与DNA结合的能力，但MTM 3-戊基侧链的改变导致了与MTM具有相同的DNA结合专一性但结合亲和力低于MTM的化合物(Mithramycin SK)。虽然这种化合物在启动子报告、基因表达和抗癌检测方面与MTM相似，但鉴于其与DNA的相互作用较弱，它的毒性可能比MTM小得多。本文的结果补充了最近的发现，而且，对于构效关系，特别是关于烷基侧链的构效关系，以及金酸类药物的作用机制，都可以得出新的结论。
The aureolic acid antitumor antibiotic mithramycin (MTM) inhibits both cancer growth and bone resorption by cross-linking GC-rich DNA, thus blocking binding of Sp-family transcription factors to gene regulatory elements. Transcription of c-src, a gene implicated in many human cancers and required for osteoclast-dependent bone resorption, is regulated by the binding of Sp factors to specific elements in its promoter. Therefore, this gene represents an important anticancer target and a potential lead target through which MTM displays its so far uncharacterized action against osteoclastic bone resorption. Here we demonstrate, using DNA binding studies, promoter reporter assays, and RT-PCR, that MTM inhibits Sp binding to the c-src promoter region, thereby decreasing its expression in human cancer cells. Furthermore, selected mithramycin analogues, namely, premithramycin 13, mithramycin SK, 7-demethylmithramycin, 4E-ketomithramycin, and 4C-ketodemycarosylmithramycin, generated through combinatorial biosynthesis, were compared with MTM for their ability to block Sp binding to the c-src promoter. Although most of the tested compounds lost their ability to bind to the DNA, alteration of the MTM 3-pentyl side chain led to a compound (mithramycin SK) with the same DNA binding specificity but with lower binding affinity than MTM. While this compound was comparable to MTM in promoter reporter, gene expression, and anticancer assays, given its weaker interaction with the DNA, it may be much less toxic than MTM. The results presented here supplement recent findings and, moreover, allow new conclusions to be made regarding both the structure-activity relationships, particularly with respect to the alkyl side chains, and the mechanism of action of aureolic acid drugs.