Mitochondrial pyruvate dehydrogenase kinase 1 drives bevacizumab resistance and malignant phenotype of TNBC by enhancing mitophagy

Abstract

Bevacizumab is an anti-angiogenic agent widely used in neoadjuvant chemotherapy for advanced triple-negative breast cancer (TNBC). TNBC patients frequently acquire resistance to bevacizumab due to the hypoxic tumor microenvironment, yet the underlying molecular mechanism remains unclear. Here, we demonstrate that mitochondrial reprogramming under hypoxia is crucial for resistance to bevacizumab. Mechanically, prolonged hypoxia causes the glycolytic pathway enzyme PDK1 to accumulate inside mitochondria. In mitochondria, PDK1 exerts its non-canonical function to phosphorylate mitochondrial protein Prohibitin 2 (PHB2) at Ser190. Phosphorylation at Ser190 stabilizes PHB2 and enhances its binding with LC3, thereby initiating mitophagy. Functionally, mitochondrial PDK1 (mito-PDK1) initiates mitophagy in response to hypoxia-induced mitochondrial damage and promotes the malignant phenotype of TNBC cells. In xenograft tumors, inhibiting the function of mito-PDK1 enhances the sensitivity to bevacizumab. Collectively, our findings identify the crucial function and mechanism of mito-PDK1 in TNBC. Targeting mito-PDK1 function may emerge as a novel therapeutic strategy to address acquired resistance to bevacizumab.

Keywords: Bevacizumab; Hypoxia; Mitophagy; Pyruvate dehydrogenase kinase 1; Triple-negative breast cancer.