Anti-tumor effects of Bacteroides fragilis and Bifidobacterium bifidum culture supernatants on mouse breast cancer

Breast cancer is one of the most important causes of cancer related morbidity and mortality in the world. Breast contains several bacterial species performing specialized functions. Bacteroides and Bifidobacterium, as microbial flora, play pivotal role against breast cancer development in vivo and in vitro. In this study we evaluated the anti-proliferative and anti-tumor effects of Bacteroides fragilis (F.S), Bifidobacterium bifidum (B.S) and Bifidobacterium bifidum + Bacteroides fragilis supernatants (B.F.S) in in vivo and in vitro model of 4 T1 cell line breast cancer. Bacterial supernatants assessed in both model. Our results indicated that the relative tumor volume significantly increased in the mice receiving intratumoral PBS. Three out of the 4 mice were cleared from the tumor thoroughly in 10–25 days after administration of B.F.S. mice receiving intratumoral B.F.S significantly secreted higher interferon γ and lower IL-10 compared with the other groups. Overall, our findings indicated that intratumoral administration of B.F.S effectively inhibited the growth of breast tumors through induction of necrosis and suppressing proliferation and angiogenesis.