Emerging roles of lactic acid bacteria in protection against colorectal cancer

Table 1 List of lactic acid bacterial strains and their functions

Prevention	LAB strains	Functions
Apoptosis	Lactobacillus acidophilus	Anti-cancer cell growth and differentiation
		Direct induction of Beclin-1 and GRP78
	L. reuteri	Proliferation (Cox-2, cyclin D1) and cell survival (Bcl-2, Bcl-xL)
		Enhances MAPK activities including c-Jun N-terminal kinase and p38 MAPK
	L. acidophilus and L. rhamnosus	Induce Beclin-1 and GRP78, as well as indirectly through the induction of Bcl-2 and Bak
	L. acidophilus and L. casei	5-fluorouracil apoptosis induction
Antioxidant DNA damage	Bifidobacterium longum and L. acidophilus	Antioxidative activity, inhibiting linoleic acid peroxidation
	Streptococcus thermophilus	Releasing ROS protective factors
Immune response improvement	L. acidophilus	Stimulates DCs to produce inflammatory cytokines IL-12 and regulatory IL-10
	LTA-deficient L. acidophilus	Induces IL-10 in DCs, down-regulates IL-12 levels
		Increases densities of effector Foxp3+RORγt- Tregs
	L. acidophilus, L. casei and B. longum	Enhance the total numbers of T cells, NK cells, MHC class II+ cells, and CD4-CD8+ T cells
	L. casei Shirota (LcS)	Induces cytokines, such as IFN-γ, interleukin-β (IL-1β) and TNF-α
	B. adolescentis	Increases the production of TNF-α
Epigenetics	LTA-deficient L. acidophilus	Enhances the expression of tumor suppressor genes
New anticancerfunction	Pediococcus pentosaceus FP3	Adhere to colon cancer cells and trigger bioproduction of SCFA
	L. salivarius FP25
	L. salivarius FP35
	Enterococcus faecium FP51

LAB: Lactic acid bacteria; LTA: Lipoteichoic acid; SCFA: Short-chain fatty acid; DC: Dendritic cell; NK: Natural killer; IL: Interleukin; TNF: Tumor necrosis factor.