Progesterone Modulates Mitochondrial Functions in Human Glioblastoma Cells

A substantial literature supports the notion that cancer is a metabolic disease. Mitochondria are sexually dimorphic, and progesterone (P4) plays a key regulatory role in mitochondrial functions. We investigated the effect of P4 on mitochondrial functions in three human glioblastoma multiforme (GBM) cell lines. In dose-response and time-response studies, GBM cells were exposed to different concentrations of P4 followed by mitochondrial stress-testing with a Seahorse analyzer. Data were analyzed for oxygen consumption rate (OCR), extracellular acidification rate (ECAR), and spare respiratory capacity (SRC) to determine the effects of P4 exposure on mitochondrial respiration and rate of glycolysis. We also examined the effect of P4 on mitochondrial superoxide radical generation by confocal microscopy. As early as 1h post-P4 exposure, we found a substantial dose-dependent inhibitory effect of P4 on OCR, ECAR, and SRC in all GBM cell lines. P4 treatment altered the levels of basal respiration, maximum respiration, nonmitochondrial oxygen consumption, ATP production, and proton leak. P4 given at 80-μM concentration showed the maximum inhibitory effect compared to controls. Live imaging data showed an 11-22% increase in superoxide radical generation in all three GBM cell lines following 6h exposure to a high concentration of P4. Our data show that high-dose P4 exerts an inhibitory effect on both mitochondrial respiration and glycolysis in GBM cells. These effects would lead to decreased tumor size and rate of growth, representing a potential treatment to control the spread of GBM.