Inhibition of Tumor Initiation and Promotion by Anti-Inflammatory Agents 2

Abstract

Two nonsteroidal anti-inflammatory agents greatly reduced, but did not completely suppress, tumor promotion in mouse skin by the croton oil factor 12-0-tetradecanoylphorbol-13-acetate (TPA). The 3-steroidal anti-inflammatory agent dexamethasone, which previously completely suppressed TPA promotion, markedly reduced tumor initiation by 3-methylcholanthrene (MCA), and reduced complete carcinogenesis by MCA. The inhibition of initiation appeared to be substantially greater than that obtained previously with other agents and suggested that dexamethasone may be a valuable tool for the study of events in tumor initiation. The results also suggested that only a small part of the carcinogenic potency of MCA was due to promotion of the type brought about by TPA.