Hypoxia-induced SUMOylation of E3 ligase HAF determines specific activation of HIF2 in clear-cell renal cell carcinoma

Clear cell kidney cancer (CRCC) is initiated typically by loss of the tumor suppressor VHL, driving constitutive activation of HIF-1 and HIF-2. However, whereas HIF-1 has a tumor suppressor role, HIF-2 plays a distinct role in driving CRCC. In this study, we show that the HIF-1α E3 ligase HAF complexes with HIF-2α at DNA to promote HIF-2-dependent transcription through a mechanism relying upon HAF SUMOylation. HAF SUMOylation was induced by hypoxia, whereas HAF-mediated HIF-1α degradation was SUMOylation independent. HAF overexpression in mice increased CRCC growth and metastasis. Clinically, HAF overexpression was associated with poor prognosis. Taken together, our results show that HAF is a specific mediator of HIF-2 activation that is critical for CRCC development and morbidity.