Bacterial toxins are emerging as promising hallmarks of colorectal cancer (CRC) pathogenesis. In particular, Cytotoxic Necrotizing Factor-1 (CNF1) from E.coli deserves special consideration due to the significantly higher prevalence of this toxin gene in CRC patients with respect to healthy subjects, and to the numerous tumor-promoting effects that have been ascribed to the toxin in vitro. To further elucidate the detrimental effects of CNF1 on intestinal epithelial cells that may favor CRC onset, we first investigated the possible genotoxic effect of this bacterial toxin on intestinal epithelial cells and its ability to modulate intestinal permeability in vitro. We observed that, in normal rat intestinal epithelial cells (IEC-6), CNF1 induces DNA damage and genomic instability mainly represented by chromatid breaks and polyploidy, through the release of reactive oxidizing species. Consistently, cell cycle analysis showed that exposure of IEC-6 cells to CNF1 induces arrest in G2/M. Treatment of differentiated Caco-2 monolayers with CNF1 halved transepithelial resistance (TEER) as compared to control monolayers, and this effect was paralleled by a down-regulation of the tight junction protein ZO-1, as observed by confocal microscopy. CNF1-induced permeabilization of Caco-2 monolayer was accelerated by the addition of pro-inflammatory factors. In vivo, repeated intrarectal administration of CNF1 in mice with experimental colitis (induced by repeated DSS-treatment cycles), induced the formation of dysplastic aberrant crypt foci in colon tissue and adenomas in 50% of cases, as compared to controls (2% DSS only). Taken together, our results indicate that the CNF1 toxin from E.coli plays a role in colorectal carcinogenesis.
CNF1 toxin from E.coli induces oxidative DNA damage, intestinal permeability and colorectal neoplasia in vivo / Tozzi, Michela; Fiore, Alessia; Travaglione, Sara; Rainaldi, Gabriella; Laterza, Ilenia; Donati, Simona; Gambardella, Lucrezia; Marcon4, Francesca; Pietraforte, Donatella; Cristina Quattrini, Maria; Vincentini, Olimpia; Spadaro, Francesca; Carollo, Maria; Macchia, Daniele; Spada, Massimo; Tommasoni, Sofia; Verin, Ranieri; De Angelis, Roberta; Fabbri And Laura Bracci, Alessia. - (2024). (Intervento presentato al convegno ACC - Alleanza contro il cancro tenutosi a Reggio Emilia).
CNF1 toxin from E.coli induces oxidative DNA damage, intestinal permeability and colorectal neoplasia in vivo
Michela Tozzi;Alessia Fiore;Ilenia Laterza;
2024
Abstract
Bacterial toxins are emerging as promising hallmarks of colorectal cancer (CRC) pathogenesis. In particular, Cytotoxic Necrotizing Factor-1 (CNF1) from E.coli deserves special consideration due to the significantly higher prevalence of this toxin gene in CRC patients with respect to healthy subjects, and to the numerous tumor-promoting effects that have been ascribed to the toxin in vitro. To further elucidate the detrimental effects of CNF1 on intestinal epithelial cells that may favor CRC onset, we first investigated the possible genotoxic effect of this bacterial toxin on intestinal epithelial cells and its ability to modulate intestinal permeability in vitro. We observed that, in normal rat intestinal epithelial cells (IEC-6), CNF1 induces DNA damage and genomic instability mainly represented by chromatid breaks and polyploidy, through the release of reactive oxidizing species. Consistently, cell cycle analysis showed that exposure of IEC-6 cells to CNF1 induces arrest in G2/M. Treatment of differentiated Caco-2 monolayers with CNF1 halved transepithelial resistance (TEER) as compared to control monolayers, and this effect was paralleled by a down-regulation of the tight junction protein ZO-1, as observed by confocal microscopy. CNF1-induced permeabilization of Caco-2 monolayer was accelerated by the addition of pro-inflammatory factors. In vivo, repeated intrarectal administration of CNF1 in mice with experimental colitis (induced by repeated DSS-treatment cycles), induced the formation of dysplastic aberrant crypt foci in colon tissue and adenomas in 50% of cases, as compared to controls (2% DSS only). Taken together, our results indicate that the CNF1 toxin from E.coli plays a role in colorectal carcinogenesis.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
