Table 2.

Inhibitory and therapeutic effects and mechanisms of some probiotics on colorectal cancer.

Probiotics	Function	Mechanism
L. gallinarum	Restrain the development of CRC	Secretion of protective metabolites including ILA to promote apoptosis of cancer cells. 67 Modulation of gut microbial composition by enriching probiotics and eliminating potential CRC pathogens inhibits CRC development. 67
L. rhamnosus GG	Restrain the development of CRC; Inhibited cell growth and induced apoptosis	Increase the expression of Bax, casp3, p53, and other apoptosis promoting proteins 68 Inhibit the expression of inflammatory proteins 69 Increased claudin-3 protein expression 59
Bifidobacterium	Anti-inflammatory effect. Inhibit proliferation of colorectal cancer cells	Increase the activity of the enzyme alkaline phosphatase 34 Enhance DC and CD8+ T-cell functions 70
E. coli Nissle 1917 (EcN)	Anti-inflammatory effect	Inhibit inflammation61,62; Induce expression of IL-22 61 ;
A. muciniphila	Cancer immunotherapy treatments; Reduce the incidence rate of CRC Anti-inflammatory effect	Restore activity against cancer cells by blocking immune checkpoints such as PD-1; 71 Modulate CTLs; 72 Prevent CRC by inhibiting Th17 to produce IL-17; 48 Reduces the expression of TLR4, regulates the NF-κB pathway, reduces the secretion of IL-6 and IL-8. 73
C. butyricum	Inhibit intestinal tumor development	Modulate Wnt-signaling and gut microbiota. 74
B. polyfermenticus	Inhibition of cancer cell growth	Produce bacteriocin 34
L. plantarum ZLP001	Anti-inflammatory effect	Decrease IL-6, IL8, and TNF-α levels 64
L. reuteri	Inhibition of Helicobacter pylori Anti-inflammatory effect	Inhibits the colonization of Helicobacter pylori and produces reuterin 52 Reduced production of pro-inflammatory mediators, NOS and pro-inflammatory cytokines 56
L. casei BL23	Immunomodulatory treatment Inhibit inflammation-associated CRC	Downregulate IL-22 cytokine, upregulate antiproliferative properties through Bik, caspase-7, and caspase-9; 75 Suppresses inflammation-associated colon cancer by producing histamine 76

Abbreviations: CRC, colorectal cancer, DC, dendritic cell; IL, interleukin; NOS, nitric oxide synthase, TLR, toll-like receptor; TNF, tumor necrosis factor.