Small-Molecule Targeting of E3 Ligase Adaptor SPOP in Kidney Cancer

In the cytoplasm of virtually all clear-cell renal cell carcinoma (ccRCC), speckle-type POZ protein (SPOP) is overexpressed and misallocated, which may induce proliferation and promote kidney tumorigenesis. In normal cells, however, SPOP is located in the nucleus and induces apoptosis. Here we show that a structure-based design and subsequent hit optimization yield small molecules that can inhibit the SPOP-substrate protein interaction and can suppress oncogenic SPOP-signaling pathways. These inhibitors kill human ccRCC cells that are dependent on oncogenic cytoplasmic SPOP. Notably, these inhibitors minimally affect the viability of other cells in which SPOP is not accumulated in the cytoplasm. Our findings validate the SPOP-substrate protein interaction as an attractive target specific to ccRCC that may yield novel drug discovery efforts. [Display omitted] •Computational design and synthetic optimization yield SPOP inhibitors•SPOP inhibitors suppress oncogenic SPOP-signaling pathways in ccRCC•SPOP inhibitors induce cell death and prevent tumor progress of ccRCC•Inhibiting SPOP-substrate interactions may be a potential approach against ccRCC Using a structure-based design followed by hit optimization, Guo et al. report small-molecule inhibitors that disrupt oncogenic SPOP-mediated pathways by blocking SPOP-substrate interactions and suppress human clear-cell renal cell carcinoma in vitro and in vivo, suggesting the potential of SPOP-targeted therapy.