Methylnitrosourea (MNU)–induced carcinogenesis and inflammation in some selected organs of female albino rats
Methylnitrosourea (MNU) is an alkylating agent which exhibits its toxicity by transferring its methyl group to nucleobases in nucleic acids, causing AT:GC transition mutations. It was originally designed as a chemotherapeutic alkylating compound, but later proven to exert direct carcinogenic, mutagenic and teratogenic potential. The carcinogenic effect of methylnitrosourea in some selected organs of female albino rats was evaluated using a modified protocol. Histopathological assessment of breast, liver, lungs and skin tissues of experimental animals was carried out using H and E staining procedure. Tumour markers, cancer antigen 15.3, 27.29 and carcinoembryonic antigen (CEA) in the blood of experimental animals were evaluated using an automated procedure. Histopathological examination revealed severe panniculitis in skin tissues, sinusoidal congestion in liver tissues, severe pulmonary inflammation in lung tissues, and stromal fibrosis in breast tissues. There was an increase in tumour marker levels in the blood of MNU induced rats compared to the controls group of rats. There was a significant difference between the values of CA 15.3 (p < 0.01) and CEA (p < 0.05) in rats induced with MNU when compared with the control. Cancer antigen 27.29 values showed no significant difference between the rats induced with MNU and control. Different forms of early stages of carcinogenesis were induced in female Albino rats using a novel and modified cancer induction protocol. Knowledge from this study did not only provide insight into possible harmful effects of MNU which could be obtained from foods containing nitrosamines, but it also provided the opportunity to test and prove a modified protocol of cancer induction which could be used to evaluate the preventive and therapeutic effect of different agents for human breast cancer within a short period of time.