Bacteriocins: New Potential Therapeutic Candidates in Cancer Therapy.

Cancer is one of the most important disorders which is associated with high mortality and high costs of treatment for patients. Despite several efforts, finding, designing and developing, new therapeutic platforms in the treatment of cancer patients are still required. Utilization of microorganisms, particularly bacteria has emerged as new therapeutic approaches in the treatment of various cancers. Increasing data indicated that bacteria could be used in the production of a wide range of anti-cancer agents, including bacteriocins, antibiotics, peptides, enzymes, and toxins. Among these anti-cancer agents, bacteriocins have attractive properties, which make them powerful anti-cancer drugs. Multiple lines evidence indicated that several bacteriocins (i.e., colcins, nisins, pediocins, pyocins, and bovocins) via activation/inhibition different cellular and molecular signaling pathways are able to suppress tumor growth in various stages. Hence, identification and using various bacteriocins could lead to improve and introduce them to clinical practices. Here, we summarized various bacteriocins which could be employed as anti-cancer agents in the treatment of many cancers.

An Escherichia coli O157-specific engineered pyocin prevents and ameliorates infection by E. coli O157:H7 in an animal model of diarrheal disease.

AvR2-V10.3 is an engineered R-type pyocin that specifically kills Escherichia coli O157, an enteric pathogen that is a major cause of food-borne diarrheal disease. New therapeutics to counteract E. coli O157 are needed, as currently available antibiotics can exacerbate the consequences of infection. We show here that orogastric administration of AvR2-V10.3 can prevent or ameliorate E. coli O157:H7-induced diarrhea and intestinal inflammation in an infant rabbit model of infection when the compound is administered either in a postexposure prophylactic regimen or after the onset of symptoms. Notably, administration of AvR2-V10.3 also reduces bacterial carriage and fecal shedding of this pathogen. Our findings support the further development of pathogen-specific R-type pyocins as a way to treat enteric infections.

Treatment of Pseudomonas aeruginosa infections with pyocines.

The interactions of a contractile, a filamentous and a small pyocine with a sensitive strain of Pseudomonas aeruginosa (no. P14) were examined in vivo. The purification procedure used yielded high-activity pyocine preparations that were not toxic to mice. The inhibitory activity of such preparations, when injected into mice by various routes, was retained for up to 24 h. However, high molecular-weight pyocines given intraperitoneally in the presence of a lethal dose of strain P14 administered by the same route did not prevent the fatal outcome of infection unless they are given before or together with the bacteria. The small pyocine had no protective effect. In burned mice infected with strain P14, topical application of a filamentous pyocine failed to improve the chances of survival. The results suggest that there is little future for pyocine therapy.