Uncoupled glycerol-3-phosphate shuttle in kidney cancer reveals that cytosolic GPD is essential to support lipid synthesis

The glycerol-3-phosphate shuttle (G3PS) is a major NADH shuttle that regenerates reducing equivalents in the cytosol and produces energy in the mitochondria. Here, we demonstrate that G3PS is uncoupled in kidney cancer cells where the cytosolic reaction is ∼4.5 times faster than the mitochondrial reaction. The high flux through cytosolic glycerol-3-phosphate dehydrogenase (GPD) is required to maintain redox balance and support lipid synthesis. Interestingly, inhibition of G3PS by knocking down mitochondrial GPD (GPD2) has no effect on mitochondrial respiration. Instead, loss of GPD2 upregulates cytosolic GPD on a transcriptional level and promotes cancer cell proliferation by increasing glycerol-3-phosphate supply. The proliferative advantage of GPD2 knockdown tumor can be abolished by pharmacologic inhibition of lipid synthesis. Taken together, our results suggest that G3PS is not required to run as an intact NADH shuttle but is instead truncated to support complex lipid synthesis in kidney cancer. [Display omitted] •Glycerol-3-phosphate shuttle is uncoupled in some cancers such as kidney cancers•High flux through cytosolic GPD supports lipid synthesis and cancer proliferation•Loss of mitochondrial GPD upregulates the expression of cytosolic GPD•Low-GPD2 expressing tumors are more sensitive to lipid synthesis inhibition Yao et al. demonstrate that the glycerol-3-phosphate shuttle is uncoupled in kidney cancers where the cytosolic reaction is faster than the mitochondrial reaction. High flux through cytosolic GPD is important for redox homeostasis and lipid synthesis. Loss of mitochondrial GPD promotes tumor growth and sensitizes tumors to lipid synthesis inhibitors.