The c-Myc oncoprotein, a helix-loop-helix-leucine zipper (HLH-ZIP) transcription factor, is frequently deregulated in human cancers. All known functions of c-Myc, including those pertaining to transformation, require that it heterodimerize with another HLH-ZIP protein, Max. Using a high throughput yeast-based assay, we identified seven low molecular weight substances that inhibit c-Myc-Max association. Each compound also prevented this interaction in vitro and inhibited the growth of c-Myc-expressing fibroblasts, although not of fibroblasts lacking c-Myc. Finally, short-term exposure of c-Myc over expressing fibroblasts to several of the compounds markedly reduced their in vivo tumorigenicity. These studies suggest that yeast-based assays can be used to identify inhibitors of protein-protein interactions and that these frequently function in mammalian cells. The signature specificities of each of the c-Myc-Max compounds identified here further suggest synergistic in vivo function.
c-Myc 癌症蛋白是一种螺旋-环-螺旋-亮
氨酸拉链(HLH-ZIP)转录因子,在人类癌症中经常发生失调。c-Myc 的所有已知功能,包括与转化有关的功能,都需要它与另一种 HLH-ZIP 蛋白 Max 异源二聚体。利用基于酵母的高通量试验,我们发现了七种抑制 c-Myc-Max 结合的低分子量物质。每种化合物都能在体外阻止这种相互作用,并抑制表达 c-Myc 的成纤维细胞的生长,但不能抑制缺乏 c-Myc 的成纤维细胞的生长。最后,将过度表达 c-Myc 的成纤维细胞短期暴露于几种化合物中,可明显降低它们在体内的致瘤性。这些研究表明,基于酵母的检测方法可用于鉴定蛋白质-蛋白质相互作用的
抑制剂,而且这些
抑制剂经常在哺乳动物细胞中发挥作用。这里发现的每种 c-Myc-Max 复合物的特征特异性进一步表明它们在体内具有协同作用。