CONICET | Buscador de Institutos y Recursos Humanos

Breast cancer represents the 2ºcause of death in women, being the metastasis an important associated complication. L. casei CRL431 is a probiotic bacteria with many beneficial effects, related especially to the modulation of the host immunity. Our aim was to evaluate the effect of milk fermented by L. casei CRL431 (FM) on the lung metastasis, when it was administered after tumour was measurable. BALB/c mice were injected with 4T1 cells in the mammary glands, and when the tumors were measurable, were divided into 3 groups: control (C),milk (M) or FM, according they received water, milk or FM. Tumour volume was calculated until day 35. Mice were sacrificed at day 70. Blood serum was obtained for MCP-1, IL6 and IL10 determinations by ELISA, and tumour and lung tissues for angiogenesis by immunhistochemestry and histological observations, respectively. FM administration delayed tumor growth and angiogenesis and showed less metastasis in the lungs compared to C and M groups. 50-70% of mice from FM group did not show metastasis or showed small focus in their lungs compared to 25-30% in C and M groups. IL6 decreased significantly in serum from mice given FM compared to C and M group. This cytokine increases in M and C groups were related with increases in the tumour angiogenesis and lung metastasis. MCP-1 concentrations also increased in the serum of these mice compared to FM group, which could be related with more infiltration of macrophages in the tumour and in the lungs. A correlation between IL10 and the presence or not of lung metastasis was not observed in mice from C and M groups. However, IL 10 increased in the serum of mice given FM, especially with lung metastasis. The results obtained showed that FM administered after the tumour was measurable, decreased the tumour growth and consequently its metastasis in the lung. This effect was related with decreasing of IL6 in serum and tumour angiogenesis.