The purpose of this study was to evaluate the potential effects of dietary
6-phenylhexyl isothiocyanate (
PHITC) on
N-nitrosomethylbenzylamine (NMBA)-induced esophageal
carcinogenesis in rats. Groups of 15 male F344 rats received weekly s.c.
injections of NMBA in 20%
dimethylsulfoxide or the vehicle alone for 15 consecutive weeks. Two weeks prior to initiation of
carcinogen or vehicle
injections rats were provided with modified AIN-76A diet or modified AIN-76A diet containing
PHITC at levels of 0.4, 1.0 or 2.5 mumol/g diet. Experimental controls consisted of groups that received only the vehicle (vehicle controls), NMBA (
carcinogen controls) or
PHITC at the high dose level of 2.5 mumol/g diet. No esophageal
tumors or preneoplastic lesions were detected in rats that received the vehicle or
PHITC alone. In contrast, all rats treated with NMBA alone or
PHITC + NMBA exhibited esophageal
tumors and preneoplastic esophageal lesions. In groups that received
PHITC + NMBA
tumor multiplicity was increased by 21-69% when compared with rats treated with NMBA alone, indicating that
PHITC enhanced esophageal
tumorigenesis in this model system. These results, in conjunction with our previous work, demonstrate that arylalkyl
isothiocyanates may inhibit or enhance esophageal
tumorigenesis in the NMBA-treated rat. The ability of
isothiocyanates to inhibit or enhance experimental
tumorigenesis may depend on alkyl chain length of the
isothiocyanate, the animal species examined and the specific
carcinogen employed.