Effect of topical applications of EHNA on the size of tumors in high risk SKH-1 mice previously treated with UVB.

Female SKH-1 mice (7–8 weeks old) were irradiated with UVB (30 mJ/cm2) twice weekly for 20 weeks, and UVB irradiation was stopped. These tumor-free mice with a high risk of developing skin tumors were treated topically with 3.1 µmole or 0.8 µmole of erythro-9-(2-hydroxy-3-nonyl) adenine hydrochloride (EHNA hydrochloride) or 6.2 µmole caffeine in 100 µl acetone:water (8∶2) once a day five days a week for 16 weeks. These mice were killed at 36 weeks after the last dose of UVB and all tumors were characterized by histopathology and the size of each tumor was determined. Each value is the mean ± SE, and the numbers in parentheses represent percent increase.Effect of topical applications of EHNA on the size of tumors in high risk SKH-1 mice previously treated with UVB.