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Published on: December 26, 2016
Small-Molecule Targeting of E3 Ligase Adaptor SPOP in Kidney Cancer
Zhong-Qiang Guo1, Tong Zheng2, Baoen Chen3
1CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China; Department of Urology, Peking University First Hospital, Beijing 100034, China; Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei 430071, China.
Abstract:
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.
Insights
Researchers developed small molecules targeting speckle-type POZ protein (SPOP) in kidney cancer. These inhibitors selectively kill clear-cell renal cell carcinoma (ccRCC) cells by disrupting oncogenic SPOP signaling, offering a potential new treatment avenue.
Area of Science:
- Oncology
- Molecular Biology
- Drug Discovery
Background:
- Speckle-type POZ protein (SPOP) is overexpressed and mislocalized to the cytoplasm in clear-cell renal cell carcinoma (ccRCC).
- Cytoplasmic SPOP accumulation promotes kidney cancer cell proliferation and tumorigenesis.
- Nuclear SPOP in normal cells induces apoptosis, highlighting a functional difference.
Purpose of the Study:
- To design and optimize small molecules inhibiting the SPOP-substrate protein interaction.
- To suppress oncogenic SPOP-signaling pathways in ccRCC.
- To evaluate the therapeutic potential of these inhibitors against ccRCC.
Main Methods:
- Structure-based drug design for inhibitor development.
- Hit optimization to enhance inhibitory potency.
- In vitro testing on human ccRCC cell lines and other cell types.
Main Results:
- Developed small molecule inhibitors targeting the SPOP-substrate protein interaction.
- Demonstrated that these inhibitors effectively kill human ccRCC cells dependent on oncogenic cytoplasmic SPOP.
- Showed minimal impact on the viability of cells with normal SPOP localization.
Conclusions:
- The SPOP-substrate protein interaction is a validated, specific target for ccRCC therapy.
- Small molecule inhibitors targeting cytoplasmic SPOP represent a promising strategy for ccRCC drug discovery.
- This approach offers a targeted therapy with potentially reduced side effects in non-ccRCC cells.
