Figure 1.

E-cigarette chemicals promote tumor cell migration in vitro. (A) Experimental design for cell scratch assays. Briefly, tumor cells were seeded into inserts containing a cell-free gap (scratch area) between two sides and were cultured overnight in the presence of concentrations of PG/VG from 0 to 20 µM with or without nicotine. Then, inserts were removed and invasion of the scratch area was monitored by time-lapse microscopy. (B) Representative microscope images (40X augmentation) taken at 0, 4, 12 and 24h from 1 of 3 experiments are shown. Vertical white lines show distance from cell fronts in μm, used to calculate percentage of covered scratch areas. (C) Percent of scratch area covered at 24h after insert removal fell by 0.58 (95% CI 0.39, 0.77) %/µM PG/VG (p<.001; Table 1 ) but was not affected by the presence of nicotine (p=.851). We also ran the model including the PG/VG x nicotine interaction and found no significant interaction (p=0.638). (D) Viable cell counts after 7 days increased by 0.060 (0.048, 0.071) x10⁶ cells/µM PG/VG (p<.001; Table 1 ) and dropped by -0.56 (-0.72, -0.39) x 10⁶ in the presence of nicotine (p<0.001). We also ran the model including the PG/VG x nicotine interaction and found a significant interaction (P<0.001). The PG/VG effect was about the same 0.076 (0.064, 0.088) (p<.001), whereas the nicotine main effect dropped to -0.22 ± .11 (-0.42, -0.02) (p=.029) with the interaction term being -.039 (-0.057, -0.021) (p<.001).