Anti-androgenic activity of N-nitrosodibenzylamine, N-nitrosodiphenylamine and N-nitrosodicyclohexylamine

Abstract

When 56 selected environmental chemicals were tested for the androgenic activity to Yeast Two-hybrid and reporter gene assay in the presence of 5α-dihydrotestosterone (DHT), the activity was inhibited by some of the chemicals including N-nitrosodiphenylamine (NDPA), a novel anti-androgenic compound, and one of suspected carcinogenic N-nitrosocompounds (NOCs) commonly used as material of rubber and plastic goods. We further examined 15 NOCs for anti-androgenic activity, and found that N-nitrosodibenzylamine (NDBzA) and N-nitrosodicyclohexylamine (NDCHA) as well as NDPA inhibited the activity of DHT in a dose-dependent manner. These compounds showed the competitive binding to androgen receptor (AR) against DHT and decreased the level of AR protein. Furthermore, 3 NOCs down-regulated the prostate specific antigen (PSA) at the transcriptional level in LNCaP cells. These results suggest that some NOCs antagonized the androgenic effect of DHT in the same manner as the synthetic anti-androgen, flutamide (F).