High Expression of Cyclin D1 and p21 in N-Nitroso-NMethylurea-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 continuationof our recent work, we investigated theexpressions ofcyclin d1 and p21 in nmuinducedbreast cancer of wistar albinorats.materials and methods: in this experimental study, mammary carcinoma was induced in female wistar albino rats by a new protocol which included the intraperitoneal injectionofnmu(50mg/kg)at50,65,and80daysoftheanimal’sage.theanimalswereweighed weekly and palpated in order to record the numbers, location, and sizeoftumors. subsequently tumor incidence (ti), latency period (lp), and tumor multiplicity(tm) were reported. aboutfour weeks after the tumor size reached 1.5 cm, 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.results: the efficiency of tumor induction was 65%, lp was 150 days, and a tm of 1.43 ± 0.53 per rat was noted. rt-pcr and western blot data indicated significant (p < 0.05) induction of both cyclin d1 and p21 expressions in rat mammary tumors compared with normal tissue from the control group.conclusion: these results indicate an efficient mammary tumor induction protocol for this type of rat, which is accompanied by an increase in cyclin d1 and p21 expressions.3