Investigation of the supportive therapy potential of propolis extract and Lactobacillus acidophilus LA-5 milk combination against breast cancer in mice.

Abstract

Immunotherapy has been applied in cancer treatments for many years as an alternative treatment method to radiotherapy, chemotherapy. It is well known that immunotherapy could suppress tumor formation by modulating the immune system of the host. The aim of the study is to investigate supportive therapy potential of acidophilus milk (AS) and propolis extract (PE) in the mouse xenograft breast cancer model. For this purpose, firstly cytotoxic effect of PE was determined by MTT assay against 4T1 mouse breast cancer cells. Apoptotic effect of PE analyzed by flow cytometry. The antibacterial activity of PE was determined by the 96-well microplate broth-dilution method on Lactobacillus acidophilus LA-5. Then, Balb/c mice were injected subcutaneously with 4T1 cells (2x105 cells/mouse) and also mice were given daily oral gavage with PE (66mg/kg/day) and/or acidophilus milk (108 CFU/mL/mouse/day) for 14days. The Balb/c mice were weighed throughout the study, and the tumor sizes were measured by caliper at the 14th day. The proliferation of splenocytes which collected spleen from mice was measured by MTT. CD8+T cell response was analyzed by flow cytometry and results were evaluated in comparison with control and tumor control groups. The IC50 value for PE on 4T1 cells was determined as 129.25±1.90µg/mL. The apoptotic effect of PE at IC50 concentration was determined as 3.3% of cells to late-apoptosis, 4.3% of cells to pro-apoptosis and 2.5% of cells to necrosis. The MIC and MBC values for PE on L. acidophilus LA-5 were 5000ppm. The treatment of PE, AS and the combination of PE and AS were inhibited the tumor volumes by 59.16%, 28.29% and 63.39%, respectively. Acidophilus milk and PE combination significantly enhanced the ConA-, LPS- and PHA-induced splenocyte proliferation (P<0.05). The acidophilus milk and PE combination were also found to stimulate IFN- γ production. In conclusion, the best anti-tumor effect was obtained by the combination of acidophilus milk and propolis.