Bioprophylactic potential of novel human colostrum probiotics via apoptotic induction of colon cancer cells and cell immune activation.

The potential and modes of action of novel human colostrum probiotics were investigated with the aim of studying their application as an alternative in the bioprophylactic and biotherapy of colon cancer. A total of 218 isolates of Gram-positive rod and cocci bacteria obtained from the colostrum of 50 healthy lactating females were collected. Beneficial probiotic criteria from these isolates, which included growth inhibition against seven foodborne pathogens (Helicobacter pylori, Escherichia coli, Salmonella Enteritidis, Salmonella Typhimurium, Staphylococcus aureus, Bacillus cereus and Listeria monocytogenes), no blood haemolysis and tolerance to acid and bile salt conditions, resulted in only eight probiotic bacteria successfully inhibiting the proliferation of colon cancer cells at rates of 32.47-61.21%. Two probiotic bacteria with higher anticancer efficacy (Streptococcus salivarius CP163 and S. salivarius CP208) were identified using 16S rRNA sequences. High rates of cell surface hydrophobicity, autoaggregation and coaggregation were obtained from both probiotics. The probiotic mode of action involved synergic probiotic adhesion to colon cancer cells that triggered SCFA bioproduction. Apoptotic induction of colon cancer cell death through caspase-2 activity, DNA fragmentation and morphological change as assessed by AO/PI staining were also observed. Immune stimulation by S. salivarius CP163 and S. salivarius CP208 resulted in B and T-cell lymphocyte activation. This study suggests that these novel human colostrum probiotics could be applied as a functional food to facilitate a bioprophylactic strategy in colon cancer.

Characterization of Streptococcus salivarius as New Probiotics Derived From Human Breast Milk and Their Potential on Proliferative Inhibition of Liver and Breast Cancer Cells and Antioxidant Activity.

Breast milk is well known as the abundant source of beneficial bacteria. A new alternative source of human probiotic origin from breast milk is in demand and currently of interest for both the functional food industry and biopharmaceuticals. The aim in this study was to investigate the anticancer and antioxidant efficacies of the new potential probiotics isolated from human breast milk. Three strains of lactic acid bacteria (LAB) have shown their potential probiotic criteria including antimicrobial activity, non-hemolytic property, and survival in acid and bile salt conditions. These strains showed high abilities on cell surface hydrophobicity, auto-aggregation, and co-aggregation. The genera identification by 16S rRNA sequencing and comparison revealed that they were Streptococcus salivarius BP8, S. salivarius BP156, and S. salivarius BP160. The inhibition of liver cancer cells (HepG2) and breast cancer cells (MCF-7) proliferation by these probiotic strains using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was 44.83-59.65 and 29.85-37.16%, respectively. The probiotic action mode was inducted via apoptotic mechanisms since they stimulate the liver and breast cancer cell death through DNA fragmentation and positive morphological changes by acridine orange (AO) and propidium iodide (PI) staining. The antioxidant activity of these probiotics in the form of intact cells, cell free supernatant (CFS), and heat-killed cells was evaluated by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, resulting in the scavenging activity rates of 16.93-25.43, 15.47-28.03, and 13.67-23.0%, respectively. These S. salivarius probiotic strains protected the L929 mouse fibroblasts against oxidative stress with very high survival rates at 94.04-97.77%, which was significantly higher (P < 0.05) than L-ascorbic acid at 75.89-78.67% in the control groups. The results indicated that S. salivarius BP8 and S. salivarius BP160 probiotic strains could be applied as functional foods or new alternative bioprophylactics for treating liver and breast cancers.