This work aimed at investigating the protective effects of Spirulina platensis on the dimethylbenz(a)anthracene (DMBA)-induced mammary tumour in rats and determination of the Estrogen and the proliferation marker Ki67 in the tumour cells by using immunohistochemical staining. At 50 days of age, group 1 remained untreated and used as control. Rats of group 2 were treated with 5% Spirulina platenesis in food, group 3 received 35 mg/kg DMBA i.p. group 4 received 35 mg/kg DMBA i.p and fed on 5% Spirulina. Animals were sacrificed when the largest mammary tumour reached 1 2 cm in diameter or after of 6 months of animal age. All the tumours produced by DMBA were ductal carcinoma in all the animals of group 3, but in group 4 two rats had carcinoma in situ mammary tumour. The animals groups 1, 2 and 4 had no tumour and have the same histological and immunostaining features. The Ki67 expression in DMBA group was highly positive (LI= 85+ 10) but in animals of groups 1, 2 and 4, the positive cells ranged from 20% to 30%. The estrogen labelling index in DMBA group was 55+ 8 in 13/15 but the other two animals displayed negative staining. These results suggest that Spirulina platenesis is a chemotherapeutic agent that causes apoptosis to tumour cells by reduction of the number of malignant cells and resists forming cancer.
Key words: Breast cancer, KI67, ER, immunostaining, Spirulina platenesis