Anti-breast cancer effects of live, heat-killed and cytoplasmic fractions of Enterococcus faecalis and Staphylococcus hominis isolated from human breast milk

Abstract

Development of tumour that is resistant to chemotherapeutics and synthetic drugs, coupled with their life-threatening side effects and the adverse effects of surgery and hormone therapies, led to increased research on probiotics' anticancer potentials. The current study investigated the potential of live, heat-killed cells (HKC) and the cytoplasmic fractions (CF) of Enterococcus faecalis and Staphylococcus hominis as anti-breast cancer agents. MCF-7 cell line was treated with 25, 50, 100 and 200 μg/mL each of live, HKC and CF of the bacteria; and cytotoxicity was evaluated for 24, 48 and 72 h using MTT assay. The morphological features of the treated cells were examined by fluorescence microscopy. The stage of cell cycle arrest and apoptosis were quantified by flow cytometry. The bacterial effect on non-malignant breast epithelial cell line, MCF-10A, was assessed using MTT assay for 24, 48 and 72 h. All the three forms of the bacteria caused a significant decrease in MCF-7 (up to 33.29%) cell proliferation in concentration- and time-dependent manner. Morphological features of apoptosis like cell death, cell shrinkage and membrane blebbing were observed. Flow cytometry analyses suggested that about 34.60% of treated MCF-7 was undergoing apoptosis. A strong anti-proliferative activity was efficiently induced through sub-G1 accumulation (up to 83.17%) in treated MCF-7 and decreased number in the G0/G1 phase (74.39%). MCF-10A cells treated with both bacteria showed no significant difference with the untreated (>90% viability). These bacteria can be used as good alternative nutraceutical with promising therapeutic indexes for breast cancer because of their non-cytotoxic effects to normal cells.

Microbiome and Breast Cancer: New Role for an Ancient Population

“…Several in vitro and in vivo studies investigated the effect of probiotics on BC; for instance, significant inhibition of cell proliferation, induction of apoptosis, and cell cycle arrest of Enterococcus faecalis and Staphylococcus hominis are proved (114). Lakritz et al studied two groups of mice: a group manipulated to develop human breast tumors and the other group fed by a Western-style diet (high fat and sugar, low vitamin D3, vitamin C, and fiber) to develop mammary tumors.…”

Effect of breast milk microbiome on the health of mothers and newborns

“…Микробиом грудного молока влияет не только на здоровье ребенка, но и на состояние молочных желез кормящей женщины. Молочнокислые бактерии, содержащиеся в грудном молоке, обладая противомикробной активностью, подавляют рост Staphylococcus aureus, основного возбудителя лактационного мастита и инфекционных заболеваний у новорожденного, а фракции выделенных из молока Enterococcus faecalis и Staphylococcus hominis ингибируют in vitro рост раковых клеток молочной железы [31]. Общеизвестно, что ведущей причиной отказа женщин от грудного вскармливания является лактационный мастит, который вызывается резким ростом золотистого стафилококка в грудном молоке, как в монокультуре, так и в ассоциациях [32].…”

Anticarcinogenecity of microbiota and probiotics in breast cancer

“…Probiotics also produce specific growth inhibitors targeting no other than cancer cells. [99,100] Probiotic strains including B. animalis, L. acidophilus, Bifidobacterium infantis, Lactobacillus paracasei, Bifidobacterium bifidum were observed to reduce cancer cell growth in MCF7 cells. [101,102] L. helveticus R389 was involved in increased immunity booster; cytokines (including IL-10 and IL-4) and decreased growth of tumor cells when receive 4T1 mouse mammary adenocarcinoma cells injection subcutaneous to murine model (BALB/c).…”