Cereblon (CRBN) inhibits prostate cancer metastasis by negatively regulating 6-phosphogluconate dehydrogenase (6PGD)

Abstract

Metastasis is the primary cause of mortality in advanced prostate cancer, and the emergence of resistance to androgen receptor (AR)-targeted therapies highlights the urgent need for alternative therapeutic strategies. Metabolic reprogramming has increasingly been recognized as a key driver of metastatic progression. In this study, we uncover a novel tumor-suppressive role for cereblon (CRBN), a substrate receptor of the CRL4CRBN E3 ubiquitin ligase complex, in modulating prostate cancer metastasis through regulation of 6-phosphogluconate dehydrogenase (6PGD), a critical enzyme in the oxidative pentose phosphate pathway (oxPPP). CRBN directly binds a conserved C-terminal α-helix in 6PGD, promoting its polyubiquitination and proteasomal degradation independently of immunomodulatory drugs (IMiDs). Genetic or pharmacological loss of CRBN via CRISPR/Cas9, RNA interference, or PROTAC-mediated degradation stabilized 6PGD and elevated the NADPH/NADP+ ratio. Conversely, re-expression of wild-type CRBN reduced 6PGD levels, restored NADPH/NADP+ ratio, and suppressed cell migration and invasion. Transcriptomic profiling revealed CRBN-induced upregulation of CDH1 and downregulation of the EMT marker MMP1, while CRBN degradation produced the opposite pattern—both effects were reversed by 6PGD inhibition. These regulatory effects were conserved across multiple cancer cell lines and observed in CRBN-deficient mouse tissues. Functional studies using intra-splenic xenograft models further demonstrated that CRBN suppresses metastatic dissemination. Collectively, our findings identify 6PGD as a novel endogenous substrate of CRBN and establish the CRBN–6PGD axis as a critical metabolic checkpoint in prostate cancer metastasis. Therapeutic targeting of this pathway may offer promising strategies for CRBN-deficient or 6PGD-driven cancers.