Enhancement of beta-propiolactone tumorigenesis in mouse skin by pretreatment with the anti-inflammatory steroid fluocinolone acetonide.

Using a two-step carcinogenesis protocol, SENCAR mice were initiated with 25 micrograms 7,12-dimethylbenz[a] anthracene (DMBA) and were then treated twice weekly with either (a) 0.5 mg beta-propiolactone (BPL) or (b) 1 microgram fluocinolone acetonide (FA) followed in 30 min by 0.5 mg BPL. The tumor incidence for the group receiving FA prior to BPL was significantly greater than for BPL alone (P less than 0.0005). Under these experimental conditions, BPL alone showed neither promoting activity nor complete carcinogenic activity. These results were not anticipated, but the reasons for their occurrence are being explored.