Table 1.

Collection of bacterial peptides proposed for CRC therapy.

Protein/Peptides	Bacterial Source	Mode of Action	Refs.
Enterotoxin (CPE)	Clostridium perfringens	Binds to Claudin-3/-4 surface receptors and leads to CRC cell lysis in SW480, HCT-116, SW620, Caco-2, HT-29 and PDX CRC cells.	[62,63]
		Induces TNF-α-upregulation leading to decreased Claudin-4 expression, disrupted tight junctions, reduced EMT-, adherence- and metastasis-capacity in HT-29 CRC cells.	[93]
Diphteria toxin (DT)	Corynebacterium diphteria	Subunit A blocks protein synthesis by ADP-ribosylation of EF-2 leading to cell death.	[65,66]
		Non-toxic CRM197 suppresses angiogenesis and proliferation in SW480, SW620, HCT-116, Caco-2 and HT-29 CRC cells.	[67,68]
Nisin	Lactococcus lactis	Leads to apoptosis via promoting hole formation in the cell membrane of Caco-2 and HT-29 CRC cells.	[69]
		Prevents expression of MMP-2, MMP-9, CDTs and Cif in SW480, HT-29, Caco-2 and LS-180 CRC cells.	[70,71]
		Increases cytotoxicity of anti-cancer agents resulting in lower doses necessary for treatment.	[70]
Colicin	Escherichia coli	Acts cytotoxically through membrane hole formation, and non-specified DN/RNase activity in HT-29 CRC cells.	[72,73]
		Subunits A, E1, E3, U inhibit cell growth and promote apoptosis in HT-29 CRC cells.	[73,74]
Microcin	Klebsiella pneumonia	Pore forming into cell membranes, thus leading to apoptosis in CRC cells and other cancer cell lines such as HeLa.	[75,76]
		Subunit E492 shows a noticeable cytotoxicity especially in HT-29 but also in SW620 CRC cells.	[94]
		Subunit E492 reduces tumor proliferation in a xenograft model with SW620 CRC cells.	[94]
Pediocin	Pediococcus acidilactici	Shows lethal effects on HT-29 and DLD-1 CRC cells.	[78]
		Subunit PA-1 interoperates with TLRs and initiates cell death.	[79]
		Inhibits cancer cell proliferation as a carrier combination.	[95]
Phenazine	Pseudomonas aeruginosa	Subtype PDC weakens viability and DNA synthesis and initiates cell cycle arrest leading to apoptosis in HT-29 CRC cells.	[80,81]
Azurin	Pseudomonas aeruginosa	Influences p53/EphB2/VEGFR-2 signaling pathway and prevents angiogenesis in CRC cells.	[26,84]
		Inhibits cancer cell mobility and shows strong anti-cancer effect in HCT-116 CRC cells.	[96]
Exotoxin A (PE)	Pseudomonas aeruginosa	Inhibits EF-2 and protein biosynthesis via ADP-ribosylation, induces apoptosis in HCT116, HT-29 and COLO320 CRC cells.	[86,87,89]
		Subtype PE24-based amyloid injection leads to growth arrest and metastasis prevention in CRC-diseased mice.	[97]
Listeriolysin O (LLO)	Listeria monocytogenes	Acts as a membrane-damaging cytotoxin in Caco-2 CRC cells.	[98]
		Shows hemolytic activity and anti-tumor properties in Colo205 CRC cells.	[90,92]