Figure 3. The key enzymes driving glucose commitment to the TCA cycle are highly expressed in CD44⁺CD117⁺ovarian cancer cells.

A. In this schematic representation of the major steps of glucose metabolism, the PKM enzyme catalyses the conversion of phosphoenolpyruvate to pyruvate, but the key enzyme that drives its ultimate destination to oxidative metabolism is pyruvate dehydrogenase (PDH). The action of PDH is in turn regulated by PDHK, which phosphorylates PDH, thus inhibiting its function. TCA, tricarboxylic acid. B. WB analysis of phospho-PDH (pPDH), PDHK1, and total PDH expression in FACS-sorted CD44⁺CD117⁺ (+/+) and CD44⁺CD117⁻ (+/−) cells from EOC effusions. Results in two representative samples are shown on the left. Ratios of protein expression in CD44⁺CD117⁺ cells vs. CD44⁺CD117⁻ cells were calculated as described in the legend to Fig. 2D. The graph shows mean expression ratios ± SD calculated from three experiments. *p < 0.05. C. FACS-sorted CD44⁺CD117⁺ and CD44⁺CD117⁻ cells from EOC ascitic fluid samples were analysed by confocal immunofluorescence for the expression of the MCT4 lactate transporter. Nuclei were stained with TOPRO3. One representative experiment is shown on the left, and the histogram on the right shows mean values ± SD of MCT4 mean fluorescence intensity (MFI) from 10 different fields. *p < 0.05. D. CD44⁺CD117⁺ (+/+) and CD44⁺CD117⁻ (+/−) cells from EOC ascitic fluid samples were FACS-sorted and MCT4 expression analysed by WB. Results from four representative samples are shown on the left. The ratio of MCT4 expression in CD44⁺CD117⁺ cells vs. CD44⁺CD117⁻ cells was calculated as described in the legend to Fig. 2D. The graph shows the mean expression ratio ± SD calculated from six experiments. *p < 0.05.