Fig. 1: KRAS activation reduces α-KG level by enhancing TCA cycling in PDAC cells.

a Relative α-KG levels in PaTu-8988t cells transfected with a control siRNA or KRAS siRNA and cultured in medium with or without Gln for 24 h. The determined α-KG levels were normalized to the numbers of viable cells (means ± SEM, n = 3). b Relative α-KG levels in HEK293T cells with or without expression of the human KRAS G12V mutant cultured in medium with or without 4 mM Gln for 24 h. The determined α-KG levels were normalized to the numbers of viable cells (means ± SEM, n = 4). c The indicated cells were cultured in medium without Gln for 24 h followed by pretreatment with DM-α-KG (7 mM) for 6 h. The α-KG levels were determined in the cells after DM-α-KG removal at 0, 1, 2, and 4 h (means ± SEM, n = 5). Data were normalized to the numbers of cells. See Supplementary Fig. S1j for a detailed experimental design. d–g U-¹³C-glutamine metabolic flux analyses in the PaTu-8988t cells. Mass isotopolog distributions of glutamate (d), α-KG (e), fumarate (f), and aspartate (g) are shown (means ± SEM, n ≥ 5). h Schematic model of U-13C-glutamine metabolism in the TCA cycle. Black arrows indicate oxidative metabolism. Red and white circles indicate labeled and unlabeled carbons, respectively. Statistical significance was determined by unpaired two-tailed Student’s t-test, ns not significant.