ZNF395 Is a Hypoxia-Responsive Regulator of Mitochondrial Glutaminolysis in Clear Cell Renal Cell Carcinoma.

Abstract

Hypoxia signaling induced by VHL deficiency fuels growth but also imposes metabolic stress on clear cell renal cell carcinomas (ccRCC). Many ccRCC cells depend on glutamine as the primary source of tricarboxylic acid (TCA) anaplerosis. Hypoxia-inducible factor α (HIFα) governs glycolysis but does not directly regulate glutamine metabolism; instead, the factor responsible for orchestrating glutamine metabolism and mitochondrial adaptations to hypoxia remains elusive. In this study, we showed that ZNF395 is a hypoxia-responsive factor that regulates glutamine metabolism in the mitochondria. When activated by a HIF2α-modulated superenhancer, ZNF395 facilitated the transcription of enzymes essential for glutaminolysis, including glutaminase (GLS) and isocitrate dehydrogenase 2. Functionally, ZNF395 depletion resulted in reduced TCA cycle intermediates and their derivatives, including amino acids, glutathione, and pyrimidine nucleotides, leading to impaired mitochondrial respiration. Restoration of mitochondrial complex I function and GLS expression partially rescued the effects of ZNF395 depletion on ccRCC tumor growth. Together, this study underscores the coordinated role of HIFα and ZNF395 in shaping metabolic adaptations in response to hypoxia in VHL-deficient ccRCCs. ZNF395 and HIF are complementary mediators of hypoxia-induced metabolic reprogramming and therapeutic targets in VHL-deficient kidney cancer, with the former regulating glutamine metabolism and the latter regulating glucose metabolism.