Oxygen-dependent subcellular redistribution of PHD3 links the hypoxic microenvironment to mitochondrial metabolic reprogramming in ccRCC

Abstract

Clear cell renal cell carcinoma (ccRCC) is characterized by profound metabolic dysregulation, with both prolyl hydroxylase domain protein 3 (PHD3) and pyruvate carboxylase (PC) independently implicated in disease progression. Although each influences patient outcomes, a direct mechanistic interplay between these two regulators has remained elusive. Here, we uncover a novel regulatory axis involving PHD3 and PC by identifying an unexpected subcellular behavior of PHD3, namely, its dual localization to the cytosol and the mitochondrial matrix. We show that mitochondrial import of PHD3 is associated with its intracellular clustering, a process modulated by PHD3 hydroxylase activity and oxygen levels. Once in the matrix, PHD3 directly hydroxylates PC, suppressing its enzymatic activity. In ccRCC with elevated PHD3 expression, this modification restricts anaplerotic flux into the tricarboxylic acid cycle, leading to impaired proliferation, reduced metastasis, and enhanced apoptosis. Together, our findings provide a new framework for targeting cancer metabolism by establishing a previously unrecognized mechanistic link between PHD3-mediated oxygen sensing within the tumor microenvironment and the regulation of ccRCC mitochondrial metabolism through the subcellular re-localization of PHD3. Clear cell renal cell carcinoma (ccRCC) is a formidable cancer, often diagnosed at advanced stages with poor survival rates. This study explores the role of prolyl hydroxylase domain protein 3 (PHD3) in ccRCC, focussing on its interaction with pyruvate carboxylase (PC), a key enzyme in cancer metabolism. The authors used various cell lines and advanced techniques such as confocal microscopy and mass spectrometry to investigate localization and function of PHD3. They discovered that PHD3 re-locates to mitochondria, where it hydroxylates PC, inhibiting its activity and reducing cancer cell growth and invasion. This inhibition limits the anaplerotic flux into the tricarboxylic acid cycle, a crucial metabolic pathway for cancer cells. The study highlights PHD3 as a potential therapeutic target, suggesting that targeting the PHD3–PC axis could offer new treatment strategies for ccRCC by exploiting its metabolic vulnerabilities. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author.