Figure 2

Enhanced survival of Fhit-deficient cells after UVC and mitomycin C treatment. (A) Graphic representation of the percent of cells surviving after 60 J m⁻² UVC treatment. Fhit-positive cells undergo UVC-induced apoptosis, as seen in the decreasing percent of surviving cells. Fhit-negative cells do not show a decrease in survival until 20 h after UVC treatment, and show two-fold more surviving cells by 28 h after treatment (P<0.0001, for difference between the decrease in survival of +/+ and −/− cells at 28 h). (B) Fhit +/+ and −/− cells were treated with 5 μ M mitomycin C and surviving fractions determined. Fhit +/+ cells demonstrate a gradual decrease in survival over time, whereas Fhit −/− cells continue to proliferate before a more gradual decrease in survival. (Two-tailed t-test reveals that decrease in survival at 24 h is significant (P=0.0079).) Survival experiments were in duplicate or triplicate. Two-tailed Fisher's exact test computed at http://www.matforsk.no/ola/fisher.htm. (C) H1299D1+P (Fhit positive) and H1299D1-P (Fhit negative) cells were exposed to 60 J m⁻² UVC. Fhit-positive cells died rapidly while Fhit-negative cells show a survival rate >60% at 24 h post UVC (P<0.0001 for survival difference at 24 h). (D) Expression of Fhit protein in Fhit-transfected cells. Lane 1: H1299D1, no induction; lanes 2–5: H1299D1 after Ponasterone A induction for 16, 24, 48, 96 h, respectively; lane 6: MKN74E4; lane 7: MKN74A66; lane 8: MKN74A116; lane 9: human lung tissue. The higher Fhit band in lanes 7 and 8 is a result of the FLAG tag (Siprashvili et al, 1997). Lane 9 shows a small amount of phosphorylated Fhit (Pekarsky et al, 2004).