Reduction by dietary matrix metalloproteinase inhibitor BAY 12-9566N of neoplastic development induced by diethylnitrosamine, N-nitrosodimethylamine, or 7,12-dimethylbenz(a)anthracene in rats.

BAY 12-9566N (BAY), which is a substituted 4-biarylbutyric acid and has the properties of a matrix metalloproteinase (MMP) inhibitor, was tested in the accelerated cancer bioassay (ACB). In the ACB, three different genotoxic carcinogens were administered individually to groups of male and female Wistar rats, in initiation (IN) segments lasting 10 weeks, followed by BAY in promotion segments lasting 42 weeks, for a total of 52 weeks of treatment, followed by 12 weeks of recovery. The IN target organs in males were the liver using diethylnitrosamine (DEN), and the lungs, using N-nitrosodimethylamine (NDA), and in females, the mammary gland using 7,12-dimethylbenz(a)anthracene (DMBA). The study consisted of eight groups of 24 rats each as follows: controls (male and female), DEN alone (male), DEN/BAY (male), NDA (male), NDA/BAY (male), DMBA (female), and DMBA/BAY (female). The daily dose of BAY was 240 mg/kg in the diet, yielding a cumulative dose of 70,560 mg/kg. The cumulative doses of carcinogens were 220 mg/kg DEN, 150 mg/kg NDA, or 15 mg/kg DMBA. No significant difference in body-weight gain pattern was evident between any of the groups at 52 or 64 weeks. Rather, in males, DEN-induced hepatocellular adenomas were reduced with BAY treatment from 29% to 21% (p < 0.05) and carcinomas from 42% to 29% (p < 0.01). Also, in males, NDA-induced pulmonary adenomas were reduced with BAY treatment from 38% to 21% (p < 0.01) and carcinomas from 21% to 4% (p < 0.01). In females, DMBA-induced mammary gland adenomas were reduced from 13% to 4% (p < 0.01) and carcinomas from 54% to 42% (p < 0.05). Thus, BAY produced a consistent and significant reduction of neoplasm development in both genders in three target tissues of carcinogenicity in which neoplasms were induced by three different DNA-reactive initiators. This inhibition may be due to inhibition of MMP, leading to reduced neoplastic growth and development.