Figure 2.

A reduced E2F1 level is responsible for sensitization of NCTC-shAHR cells to UVB-induced apoptosis. (a) Protein expression of E2F1 and β-actin in NCTC-EV and NCTC-shAHR KC. *Significantly reduced compared with NCTC-EV; (b) NCTC-shAHR KC were transiently transfected with 0.75 μg of the E2F1 expression vector (pE2F1) or empty vector pCMV. After 24 h, cells were irradiated with 400 J/m² UVB, additional 24 h later western blotting was performed using the indicated antibodies. *Significantly increased compared with NCTC-EV; (c) NCTC-EV and NCTC-shAHR KC were transiently transfected with the E2F1 promoter-driven reporter construct pGL2AN or empty vector pGL2basic. Luciferase activities were measured after 48 h. Results are shown as fold of NCTC-EV empty vector controls. *Significantly reduced compared with NCTC-EV; (d) NCTC-EV and NCTC-shAHR KC were transiently transfected with pGL2AN. After 24 h, KC were treated with 5 μM BaP, 1 and 10μM Roscovitine or 0.1% DMSO, and luciferase activities were measured after additional 24 h. Results are shown as fold of DMSO-treated NCTC-EV samples. *Significantly reduced compared with NCTC-EV. (e) Basal expression of p27^KIP1 mRNA in NCTC-EV and NCTC-shAHR KC 24 h after seeding. *Significantly increased compared with NCTC-EV KC; (f) basal expression of p27^KIP1 protein in NCTC-EV and NCTC-shAHR KC 24 h after seeding. *Significantly altered compared with NCTC-EV; (g) proliferation rates of growing NCTC-EV (treated with 0.1% DMSO or 20 μM MNF) and NCTC-shAHR cells were measured by BrdU incorporation for 24 h and are given as fold of DMSO-treated NCTC-EV. *Significantly reduced compared with DMSO-treated NCTC-EV