Fig. 6

Smoke but not e-cigarette vapor shifts metabolism toward an enhanced reductive state. A Metabolomic and transcriptomic data were integrated across 3 distinct cell backgrounds (SCC152, SCC154, UDSCC2) and genes which were consistently upregulated (FDR ≤ 0.05) across all 3 backgrounds, defined within both datasets were identified: Gpx2 (glutathione peroxidase 2), Gsr (glutathione reductase). B SCC152 cells were exposed to smoke (0%, 5%, 15%) for 8 h in the presence of 25 mM ¹³C all labeled glucose (Glc). Following completion of exposure, cell lysates were analyzed for ¹³C incorporation which demonstrated reduced flux toward lactate and TCA with enhanced flux into PPP intermediates. C HN30 cells were exposed to smoke (3%) or e-cigarette vapor (5%) for 8 h. Smoke but not vapor increased Nrf2 total protein levels; β-actin was used as the protein loading control. D In contrast to smoke, vapor generated minimal effects on tumor cell viability (HN31, SCC152) even when adjustments were made for similar nicotine delivery levels (Hoechst, 72 h). Hoechst data are shown as means, normalized to control condition; error bars indicate standard error of the mean; p values are denoted as *p < 0.05. E In parallel (to experiment carried out in panel C, cells were subjected to unbiased steady state metabolomics analysis which demonstrated that smoke, but not vapor shifts tumor metabolism toward an enhanced reductive state. Two-way unsupervised hierarchical clustering of non-exposome metabolites and cell lines illustrating major differences between cells exposed to smoke and minor differences in cells exposed to vapor. Note: Panel E and Figure S3 summarize different aspects of the same experiment