Original Article High Expression of Cyclin D1 and p21 in N-Nitroso-N- Methylurea-Induced Breast Cancer in Wistar Albino Female Rats

Objective: N-nitroso-N-methylurea (NMU) induces breast cancer in rodents, particularly in rats. This model of breast cancer is very similar to human breast cancer. As a continu-ation of our recent work, we investigated the expressions of cyclin D1 and p21 in NMU-induced breast cancer of Wistar Albino rats. Materials and Methods: In this experimental study, mammary carcinoma was induced in female Wistar Albino rats by a new protocol which included the intraperitoneal in-jection of NMU (50 mg/kg) at 50, 65, and 80 days of the animal’s age. The animals were weighed weekly and palpated in order to record the numbers, location, and size of tumors. Subsequently tumor incidence (TI), latency period (LP), and tumor multi-plicity (TM) were reported. About four weeks after the tumor size reached 1.5 cm3, rats were sacrificed. Cyclin D1 and p21 expressions in tumors and normal mammary glands from normal rats were measured by reverse-transcription polymerase chain reaction (RT- PCR) and Western blot analysis. Statistical analysis of the data was performed using SPSS software version 16.0