Spoonamore James, Weïwer Michel, Wei Jianqiang, Guichard Boris, Ross Nathan T., Masson Kristina, Silkworth Whitney, Dandapani Sivaraman, Munoz Benito, Palmer Michelle, Scherer Christina, Schreiber Stuart L.
The Broad Institute Probe Development Center, Cambridge, MA
Howard Hughes Medical Institute, Chemistry & Chemical Biology, Harvard University, Cambridge, MA.
v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) is the most mutated oncogene, and KRAS mutations have been found in up to 20% of all human tumors. In 2009, Serine/threonine-protein kinase 33 (STK33) was identified as a synthetic lethal gene in KRAS-dependent cell lines through Ribonucleic Acid Interference (RNAi) experiments. Hence STK33 could potentially be a critical target in KRAS-dependent cancers. To test this hypothesis, we initiated a high-throughput screening campaign to look for STK33 inhibitors. The Molecular Libraries Small Molecule Repository (MLSMR) was screened, and two promising scaffolds were identified: one based on a thiazolone and the other one based on a quinoxalinone. Extensive SAR was performed on both scaffolds, and two new inhibitors of STK33 were discovered. These compounds (CID 5765514/ML280 and CID 53377448/ML281) will serve to test the relevance of STK33 as a viable target for the selective killing of KRAS-dependent cells. While our medicinal chemistry efforts were ongoing, a research group at Amgen described RNAi experiments conducted in a large panel of KRAS mutant and KRAS wild-type cell lines. This study concluded that STK33 is not required for the survival of KRAS mutant cell lines. In addition, the Amgen team developed small-molecule inhibitors of STK33 and demonstrated that they had no effect in selectively killing KRAS mutant cell lines. Because of the controversy on the legitimacy of STK33 as a target for the selective killing of KRAS mutant cell lines, we pursued our medicinal chemistry efforts to provide new classes of STK33 inhibitors to the cancer research community to test this hypothesis and to help elucidate the role of STK33 in different cancer cell lines. We find that our probes do not lead to KRAS dependent cell death.
v-Ki-ras2 Kirsten大鼠肉瘤病毒癌基因同源物（KRAS）是最易发生突变的癌基因，在所有人类肿瘤中，高达20%的肿瘤存在KRAS突变。2009年，通过RNA干扰（RNAi）实验，丝氨酸/苏氨酸蛋白激酶33（STK33）被鉴定为KRAS依赖性细胞系中的合成致死基因。因此，STK33可能是KRAS依赖性癌症的关键靶点。为了验证这一假设，我们启动了一项高通量筛选活动以寻找STK33抑制剂。对分子文库小分子储存库（MLSMR）进行了筛选，确定了两个有前景的骨架：一个基于噻唑酮，另一个基于喹喔啉酮。对这两个骨架都进行了广泛的构效关系研究，发现了两种新型的STK33抑制剂。这些化合物（CID 5765514/ML280和CID 53377448/ML281）将用于测试STK33作为选择性杀伤KRAS依赖性细胞的可行靶点的相关性。在我们进行药物化学研究的同时，安进公司的一个研究小组描述了在大量KRAS突变和KRAS野生型细胞系中进行的RNAi实验。该研究得出结论，KRAS突变细胞系的存活不需要STK33。此外，安进团队开发了STK33的小分子抑制剂，并证明它们对选择性杀伤KRAS突变细胞系没有作用。由于关于STK33作为选择性杀伤KRAS突变细胞系靶点的合理性存在争议，我们继续进行药物化学研究，为癌症研究界提供新型的STK33抑制剂，以验证这一假设，并帮助阐明STK33在不同癌细胞系中的作用。我们发现我们的探针不会导致KRAS依赖性细胞死亡。
