Discovery of 2-Pyrazolylpyrimidinone Derivatives as New SPOP Inhibitors for Renal Cell Carcinoma Therapy.

E3 ligase speckle-type POZ protein (SPOP) is a potential therapeutic target in clear-cell renal cell carcinoma (ccRCC). However, small-molecule inhibitors targeting SPOP are rarely reported. Here, we identified DDO-4033 as a potent SPOP inhibitor through virtual screening and optimization. This 2-pyrazolylpyrimidinone derivative exhibited potent affinity with SPOP in vitro and efficiently impeded the malignant migration, invasion, and proliferation of ccRCC cell lines. DDO-4033 disrupted the SPOP recruitment of substrate LATS1 and inhibited the polyubiquitination and subsequent degradation, resulting in the upregulation of tumor suppressor LATS1. The increased abundance of LATS1 inactivated the transcriptional factors YAP1 and WWTR1/TAZ, ultimately turning on the Hippo signaling pathway in kidney cancer cells. Our findings identify DDO-4033 as a new SPOP-targeted inhibitor with decent antitumor activity, providing a potential lead for the development of ccRCC therapy.