Hormetic and Anti-radiation Effects of Tropolone-related Compounds

Experimental protocols for UV irradiation. Effect of the amount of medium (A) and the concentration of test compound (B).

Effect of culturing in DMEM or α-MEM supplemented with 10%FBS on cumulative cell population doubling number (A-C), saturation cell density during the aging process (D-F) and growth curve (G-I) of HGF-1 (A, D, G), HPC-1 (B, E, H) and HPLF-1 (C, F, I) cells. Each value represents the mean of 6 determinantions. Significant difference (p<0.05) between DMEM and a-MEM is shown by asterisks in HPLF-1 (I).

Expression of p53 proteins in human normal and OSCC cells. Cell lysates were prepared from human oral normal cells (HGF-1, HPC-1, HPLF-1) (20 PDL) or human OSCC cell lines (HSC-2) at low cell density (L) (growing phase) or high cell density (H) (near confluent phase), and then aliquots (equivalent to 30 μg protein) were applied to Western blot analysis. The absence of p53 protein in HSC-2 cells was reproducible in another independent experiment.

Hormetic effects of group I compounds. HGF-1 (23 PDL), HPC-1 (24 PDL) and HPLF-1 (24 PDL) cells were treated for 24 (○), 48 (□) or 72 (▵) hours with [5b], [11b], [9], [21], [16] or [20], and the viable cell number was determined by MTT method. Each value represents the mean of three determinations.

HGF-1 (15 PDL) (○), HPC-1 (16 PDL) (□), HPLF-1 (15 PDL) (▵), HSC-2 (○), HSC-3 (▪) or HSC-4 (▴) cells were exposed to UV irradiation (6 J/m²/min, 1 min) for 2 minutes in 0, 0.05, 0.1, 0.2 or 0.4 ml of DMEM supplemented with 10% FBS (A) or PBS (−) (B), and then replenished with 0.1 ml of fresh DMEM. After incubation for 48 hours, the viable cells were determined by MTT method, and expressed as a % of control cells not exposed to UV irradiation. Each value represents the mean of three determinations.