Sumoylation Negatively Regulates CSR1-Dependent Prostate Cancer Cell Death.

BACKGROUND/AIMS: SUMOylation is a dynamic process and reversed by the activity of SUMO-specific proteases (SENPs) family. SENP1, a member of this family, is highly expressed and plays oncogenic roles in diverse cancers including prostate cancer. However, the SENP1-transgenic mice exhibit aberrant transformation of the mouse prostate gland but do not develop cancer. Cellular Stress Response 1 (CSR1) is a tumor suppressor gene and frequently deleted in prostate cancers. Overexpression of CSR1 in prostate cancer cells inhibits colony formation, anchorage-independent growth and induces cell death.

METHODS

The relationship between CSR1 and SENP1 were determined by immunoprecipitation-based proteomics screen and verified by GST-pull down assay. In vivo SUMOylation assay was used to detect the direct effect of SENP1 in the regulation of CSR1. Clustered regularly interspaced short palindromic repeats (CRISPR)-based gene editing was used to generate Senp1-/- and CSR1-/- PC3 cells. FACS assay was used to determine the apoptosis ratio of cells after transfection.

RESULTS

CSR1 is SUMOylated at K582 and rapid ubiquitinated and degradated in prostate cancer cells. SENP1 interacts with and deSUMOylates CSR1 to prevent its degradation and enhances CSR1-dependent prostate cancer cell death.

CONCLUSION

Thus, our data indicates that CSR1 is a critical SUMOylated substrate of SENP1 that might partially explain the controversial roles of SENP1 in prostate cancer development.