BACKGROUND: Optimal therapy for colorectal carcinoma (CRC), a frequently diagnosed malignancy, does not exist. Some of colicins and microcins, ribosomally synthesized peptides by gramnegative bacteria, have shown significant biological activity specifically against different cancer cells in vitro and in vivo conditions. The aim of this prospective study was to evaluate natural colicin and microcin production by large intestinal mucosal bacteria in each stage of colorectal neoplasia and in those with a history of colorectal neoplasia. METHODS: A total of 21 patients with non-advanced adenoma (non-a-A; 16/21 with current and 5/21 with history of non-a-A), 20 patients with advanced colorectal adenoma (a-A; 11/20 with current and 9/20 with history of a-A), 22 individuals with CRC (9/22 with current and 13/22 with history of CRC) and 20 controls were enrolled. Mucosal biopsies from the caecum, transverse colon and the rectum were taken during colonoscopy in each individual. Microbiological culture followed. Production of colicins and microcins was evaluated by PCR methods. RESULTS: A total of 239 mucosal biopsies were taken. Production of colicins and microcins was significantly more frequent in individuals with non-a-A, a-A and CRC compared to controls. No significant difference in colicin and microcin production was found between patients with current and previous non-a-A, a-A and CRC. Significantly more frequent production of colicins was observed in men compared to women at the stage of colorectal carcinoma. A later onset of increased production of microcins during the adenoma-carcinoma sequence has been observed in males compared to females. CONCLUSIONS: Strains isolated from large intestinal mucosa in patients with colorectal neoplasia produce colicins and microcins more frequently compared to controls. Bacteriocin production does not differ between patients with current and previous colorectal neoplasia. Fundamental differences in bacteriocin production have been confirmed between males and females.

• Keywords
• Colicin, Colorectal carcinoma, Colorectal neoplasia, Gramnegative bacteria, Microcin,
• MeSH
• Bacteria metabolism   MeSH
• Bacteriocins biosynthesis   MeSH
• Biopsy MeSH
• Colorectal Neoplasms pathology   MeSH
• Humans MeSH
• Gastrointestinal Microbiome * MeSH
• Intestinal Mucosa metabolism   microbiology   MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Bacteriocins MeSH

BACKGROUND: Colorectal cancer (CRC) is the 3rd most common cancer worldwide and the Czech Republic has the 6th highest incidence of CRC worldwide. Large intestinal microbiota play in its etiopathogenesis important role. Bacteriocins are proteins, produced by bacteria from the Enterobacteriaceae family. The aim of our prospective study was to assess the colonization of large intestinal mucosa by Escherichia coli strains and to investigate their bacteriocin production. METHODS: A total of 30 consecutive patients with colorectal adenoma, CRA (17 men, 13 women, aged 39-79, mean age 63 ± 9), 30 patients with CRC (23 men, 7 women, aged 38-86, mean age 67 ± 11) and 20 healthy controls (9 men, 11 women, age 23-84, mean age 55 ± 15) were enrolled into prospective study. Mucosal biopsies were taken in the caecum, transverse colon and rectum during pancolonoscopy. Microbiological culture, isolation and identification of bacteria followed. Bacteriocin production was assessed by growth inhibition of indicator strains E. coli K12-Row, E. coli C6 (phi), and Shigella sonnei 17. Identification of bacteriocin-encoding determinants and E. coli phylogroups was performed using PCR methods. RESULTS: A total of 622 strains were isolated and further investigated. A significantly higher frequency of simultaneous production of colicins and microcins was revealed in the group of patients with CRC, when compared to patients with CRA, p = 0.031. A significantly higher frequency of E. coli phylogroup D was found in patients with CRC, when compared to controls, p = 0.044. A significantly higher prevalence of bacteriocinogeny was confirmed in patients with advanced adenoma when compared to patients with non-advanced adenoma, p = 0.010. Increasing bacteriocinogeny was associated with an increasing stage of CRC (assessed according to TNM classification). Either E. coli phylogroup B2 or E. coli phylogroup D were isolated in biopsies of patients with right-sided CRC. A statistically higher incidence of E. coli phylogroup B2 was found in patients with right-sided CRC when compared to patients with left-sided CRC, p = 0.028. CONCLUSIONS: Large intestinal mucosa of patients with more advanced colorectal neoplasia is colonized with more virulent strains of E. coli and higher production of bacteriocins is observed in these patients when compared to those with less advanced colorectal neoplasia.

• MeSH
• Adenocarcinoma microbiology   pathology   MeSH
• Adenoma microbiology   pathology   MeSH
• Bacteriocins metabolism   MeSH
• Adult MeSH
• Escherichia coli isolation & purification   metabolism   MeSH
• Phylogeny MeSH
• Colicins metabolism   MeSH
• Colon microbiology   MeSH
• Colorectal Neoplasms microbiology   pathology   MeSH
• Middle Aged MeSH
• Humans MeSH
• Microbiota * MeSH
• Prospective Studies MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Case-Control Studies MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic MeSH
• Names of Substances
• Bacteriocins MeSH
• Colicins MeSH
• microcin MeSH Browser

The activity in vitro of four types of colicins (A, E1, E3, U) against one human standard fibroblast line and against 11 human tumor-cell lines carrying defined mutations of the p53 gene was quantified by MTT (tetrazolium bromide) assay. Flow cytometry showed that the pore-forming colicins A, E1 and U affected the cell cycle of 5 of these cell lines. Colicins E3 and U did not show any distinct inhibitory effects on the cell lines, while colicins E1 and especially A inhibited the growth of all of them (with one exception concerning colicin E1). Colicin E1 inhibited the growth of the tumor lines by 17-40% and standard fibroblasts MRC5 by 11%. Colicin A exhibited a differentiated 16-56% inhibition, the growth of standard fibroblasts being inhibited by 36%. In three of the lines, colicins A and E1 increased the number of cells in the G1 phase (by 12-58%) and in apoptosis (by 7-58%). These results correlated with the data from sensitivity assays. Hence, the inhibitory effect of colicins on eukaryotic cells in cell-selective, colicin-specific and can be considered to be cytotoxic.

• MeSH
• Cell Cycle drug effects   MeSH
• Eukaryotic Cells drug effects   MeSH
• Fibroblasts drug effects   MeSH
• G1 Phase drug effects   MeSH
• Colicins pharmacology   MeSH
• Humans MeSH
• Mutation MeSH
• Tumor Cells, Cultured drug effects   MeSH
• Tumor Suppressor Protein p53 genetics   MeSH
• Tetrazolium Salts metabolism   MeSH
• Thiazoles metabolism   MeSH
• Cell Survival drug effects   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Colicins MeSH
• Tumor Suppressor Protein p53 MeSH
• Tetrazolium Salts MeSH
• Thiazoles MeSH
• thiazolyl blue MeSH Browser

Colicins are toxic exoproteins produced by bacteria of colicinogenic strains of Escherichia coli and some related species of Enterobacteriaceae, during the growth of their cultures. They inhibit sensitive bacteria of the same family. About 35% E. coli strains appearing in human intestinal tract are colicinogenic. Synthesis of colicins is coded by genes located on Col plasmids. Until now more than 34 types of colicins have been described, 21 of them in greater detail, viz. colicins A, B, D, E1-E9, Ia, Ib, JS, K, M, N, U, 5, 10. In general, their interaction with sensitive bacteria includes three steps: (1) binding of the colicin molecule to a specific receptor in the bacterial outer membrane; (2) its translocation through the cell envelope; and (3) its lethal interaction with the specific molecular target in the cell. The classification of colicins is based on differences in the molecular events of these three steps.

• MeSH
• Escherichia coli chemistry   metabolism   MeSH
• Escherichia coli Infections microbiology   MeSH
• Colicins classification   metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Names of Substances
• Colicins MeSH

As a further model of mammalian tissue cells, Chinese hamster fibroblasts of the stable line V79 were used to check the cytotoxic effects of colicins. The efficiency of plating of cells treated with colicins E1-E5 and with colicin K was followed. The V79 cells were, in general, poorly sensitive to colicins; only colicins E1, E3 and E5 lowered the number of colony-forming cells to some degree. Again, a different action of colicins E1 and K (which is the same in bacteria) was found in eukaryotic cells.

• MeSH
• Cell Line MeSH
• Fibroblasts MeSH
• Colicins pharmacology   MeSH
• Cricetinae MeSH
• Cell Survival * MeSH
• Animals MeSH
• Check Tag
• Cricetinae MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Colicins MeSH