Published in Cancer Detection and Prevention 2001; 25(3):263-270.

Feeding Thiol-containing Compounds, Derived from Vegetables, Fails to Inhibit N-methylnitrosourea-induced Mammary Tumorigenesis

Leonard A. Cohen, PhD,a Zhonglin Zhao, MD,a Brian Pittman, MS,a Cesar Aliaga, BS,a and Ronald Lubet, PhD,b

aAmerican Health Foundation, Valhalla, NY, and bChemoprevention Branch, National Institutes of Health/National Cancer Institute, Bethesda, MD

Address all correspondence and reprint requests to: L.A. Cohen, PhD, American Health Foundation, 1 Dana Road, Valhalla, NY 10595.

ABSTRACT: Various thiol-containing compunds have been shown to inhibit chemically-induced tumors in animal models. Two thiol-containing compounds derived from vegetables, namely 1,2 dithiol-3-thione (DTT) and S-methylmethane thiosulfonate (MMTS), were tested for their chemopreventive activity in the N-methylnitrosourea (NMU)-induced rat mammary tumor model. Each compound was incorporated into the grain-based Teklad 7001 diet and fed to the rats one week prior to initiation with NMU until termination 18 weeks post NMU. DTT was fed at 166 and 500 ppm and MMTS at 200 and 800 ppm. Neither compound exerted a signifiacant inhibitory effect on any index of tumor development including incidence, total tumor, tumor multiplicity, volume or latency. Serum levels of DTT assessed at termination in the 500 ppm DTT group ranged from 10-30 µg/ml. MMTS was undetectable in serum from either MMTS-fed group. The results of this study, using the direct acting carcinogen, NMU, suggest that the chemopreventive effect of thiol-containing compounds may be confined to animal models using carcinogens that require host activation.

KEY WORDS: dietary thiols, chemoprevention, mammary tumor, .