Tumor suppressor SPOP ubiquitinates and degrades EglN2 to compromise growth of prostate cancer cells.

EglN prolyl hydroxylases, a family of oxygen-sensing enzymes, hydroxylate distinct proteins to modulate diverse physiopathological signals. Aberrant regulations of EglNs result in multiple human diseases, including cancer. Different from EglN1 which function largely depends on the role of hypoxia-induce factor alpha (HIFα) in tumors, the functional significance and the upstream regulatory mechanisms of EglN2, especially in prostate cancer setting, remain largely unclear. Here, we demonstrated that dysregulation of EglN2 facilitated prostate cancer growth both in cells and in vivo. Notably, EglN2 was identified highly expressed in human prostate cancer tissues. Mechanically, Cullin 3-based E3 ubiquitin ligase SPOP, a well-characterized tumor suppressor in prostate cancer, could recognize and destruct EglN2. Meanwhile, androgen receptor (AR), playing a pivotal role in progression and development of prostate cancer, could transcriptionally up-regulate EglN2. Pathologically, SPOP loss-of-function mutations or AR amplification, frequently occurring in prostate cancers, could significantly accumulate EglN2 abundance. Therefore, our study not only underlines an oncogenic role of EglN2 in prostate cancer, but also highlights SPOP as a tumor suppressor to down-regulate EglN2 in prostate cancer.