Abstract Benzyl isothiocyanate (BITC) is a hydrolysis product of glucotropaeolin, a compound found in cruciferous vegetables, and has also been shown to have anti-tumor properties. In the present study, we attempted to determine whether BITC inhibits the development of prostate cancer using the transgenic adenocarcinoma mouse prostate (TRAMP) model. Male TRAMP mice and their nontransgenic (normal) littermates at 5 wk of age were randomly divided into control and BITC-treatment groups and gavage-fed with 0 (vehicle), 5, or 10 mg/kg of BITC every other day. At the time of sacrifice (24 wk of age), BITC did not affect body weight of normal or transgenic animals. The genitourinary tract weight of TRAMP mice was increased markedly as compared to normal mice, and this increase was suppressed significantly via the oral administration of 5 or 10 mg/kg of BITC. H&E staining of the dorsolateral lobes of the prostate demonstrated that well-differentiated carcinoma (WDC) was a predominant feature in the 24 week old vehicle-fed TRAMP mice, whereas number of lobes with WDC was reduced and the number of lobes with prostatic intraepithelial neoplasia was increased by feeding with 5 or 10 mg/kg of BITC. BITC feeding reduced the number of cells expressing the Ki67 (a proliferation marker) in the prostatic tissue. Additionally, BITC feeding reduced the expression of cyclin E, cyclin D1, cyclin A, and cyclin-dependent kinase (CDK)2. Our in vitro cell culture results revealed that BITC decreased DNA synthesis and CDK2 activity in TRAMP-C2 mouse prostate cancer cells. However, BITC did not affect apoptosis either in transgenic mice in vivo or in TRAMP-C2 cells in vitro. These results indicate that inhibition of cell cycle progression contributes to the inhibition of prostate cancer development in animals treated with BITC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 609. doi:1538-7445.AM2012-609