Fig. 1: Elevated NRF2 increases xCT expression, system x_c⁻ activity, and downstream antioxidant capacity, detectable by [¹⁸F]FSPG.

a Schematic of system x_c⁻ with its natural substrates cystine and glutamate, and the radiotracer [¹⁸F]FSPG (structure shown in insert). b Protein expression of NRF2, xCT and NQO1 in a panel of NSCLC lines and corresponding KEAP1 mutations. Actin was used as a loading control. c Cystine consumption in NSCLC lines following media replenishment. Cys₂, cystine. Intracellular glutamate (d) and GSH (e) in NSCLC lines. Flow cytometric measurement of total ROS levels using CellROX Green with representative histograms (f) and median fluorescent intensity (MFI; g) shown. h Intracellular retention of [¹⁸F]FSPG. i Correlation between intracellular GSH and intracellular [¹⁸F]FSPG accumulation. Broken lines represent the 95% confidence interval of the best-fit line. Data are presented as mean ± SD from n = 3 independent experiments. Comparisons were made across the mean of n = 4 cells per group (NRF2-high vs. NRF2-low) using an unpaired two-tailed Student’s t-test for (c–e, g–h). a created with BioRender.com released under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International license, https://creativecommons.org/licenses/by-nc-nd/4.0/deed.en. For (b–e, g–i), source data are provided as a Source Data file.