Tumour-associated KRAS mutations are the most prevalent in the three RAS-family isoforms and involve many different amino-acids. Therefore, molecules able to interfere with mutant KRAS protein are potentially important for wide-ranging tumour therapy. We describe the engineering of two RAS degraders based on protein macromolecules (macrodrugs) fused to specific E3 ligases. A KRAS-specific DARPin fused to the VHL E3 ligase is compared to a pan-RAS intracellular single domain antibody (iDAb) fused to the UBOX domain of the CHIP E3 ligase. We demonstrate that while the KRAS-specific DARPin degrader induces specific proteolysis of both mutant and wild type KRAS, it only inhibits proliferation of cancer cells expressing mutant KRAS in vitro and in vivo. Pan-RAS protein degradation, however, affects proliferation irrespective of the RAS mutation. These data show that specific KRAS degradation is an important therapeutic strategy to affect tumours expressing any of the range of KRAS mutations.

肿瘤相关的KRAS突变在这三种RAS家族亚型中最普遍，并且涉及许多不同的氨基酸。因此，能够干扰突变型KRAS蛋白的分子对于广泛的肿瘤治疗潜在重要。我们描述了基于蛋白质大分子（macrodrugs）融合到特定的E3连接酶的两个RAS降解工程。将与VHL E3连接酶融合的KRAS特异性DARPin与与CHIP E3连接酶的UBOX域融合的泛RAS细胞内单域抗体（iDAb）进行比较。我们证明，虽然KRAS特异性DARPin降解物诱导突变型和野生型KRAS的特异性蛋白水解，但它仅抑制在体外和体内表达突变型KRAS的癌细胞的增殖。但是，Pan-RAS蛋白降解会影响增殖，而与RAS突变无关。