Sakamoto Kathleen M, Kim Kyung B, Verma Rati, Ransick Andy, Stein Bernd, Crews Craig M, Deshaies Raymond J
Division of Hematology-Oncology, Mattel Children's Hospital at the University of California Los Angeles, 90095-1752, USA.
Mol Cell Proteomics. 2003 Dec;2(12):1350-8. doi: 10.1074/mcp.T300009-MCP200. Epub 2003 Oct 2.
The proteome contains hundreds of proteins that in theory could be excellent therapeutic targets for the treatment of human diseases. However, many of these proteins are from functional classes that have never been validated as viable candidates for the development of small molecule inhibitors. Thus, to exploit fully the potential of the Human Genome Project to advance human medicine, there is a need to develop generic methods of inhibiting protein activity that do not rely on the target protein's function. We previously demonstrated that a normally stable protein, methionine aminopeptidase-2 or MetAP-2, could be artificially targeted to an Skp1-Cullin-F-box (SCF) ubiquitin ligase complex for ubiquitination and degradation through a chimeric bridging molecule or Protac (proteolysis targeting chimeric molecule). This Protac consisted of an SCF(beta-TRCP)-binding phosphopeptide derived from IkappaBalpha linked to ovalicin, which covalently binds MetAP-2. In this study, we employed this approach to target two different proteins, the estrogen (ER) and androgen (AR) receptors, which have been implicated in the progression of breast and prostate cancer, respectively. We show here that an estradiol-based Protac can enforce the ubiquitination and degradation of the alpha isoform of ER in vitro, and a dihydroxytestosterone-based Protac introduced into cells promotes the rapid disappearance of AR in a proteasome-dependent manner. Future improvements to this technology may yield a general approach to treat a number of human diseases, including cancer.
蛋白质组包含数百种蛋白质，理论上这些蛋白质可能是治疗人类疾病的极佳治疗靶点。然而，这些蛋白质中的许多来自从未被验证为小分子抑制剂开发可行候选物的功能类别。因此，为了充分利用人类基因组计划推进人类医学的潜力，需要开发不依赖于靶蛋白功能的抑制蛋白质活性的通用方法。我们之前证明，一种正常稳定的蛋白质，甲硫氨酸氨肽酶-2或MetAP-2，可以通过嵌合桥接分子或Protac（蛋白酶体靶向嵌合分子）人工靶向Skp1-Cullin-F-box（SCF）泛素连接酶复合物进行泛素化和降解。这种Protac由源自IkappaBalpha的与SCF（β-TRCP）结合的磷酸肽与卵霉素相连组成，卵霉素可与MetAP-2共价结合。在本研究中，我们采用这种方法靶向两种不同的蛋白质，雌激素（ER）和雄激素（AR）受体，它们分别与乳腺癌和前列腺癌的进展有关。我们在此表明，基于雌二醇的Protac可以在体外促进ERα异构体的泛素化和降解，引入细胞中的基于二氢睾酮的Protac以蛋白酶体依赖性方式促进AR的快速消失。该技术未来的改进可能会产生一种治疗多种人类疾病（包括癌症）的通用方法。
