Role of bacteria in carcinogenesis, with special reference to carcinoma of the gallbladder

Table 2 Bacterial toxins and their possible roles in carcinogenesis

Toxin	Source	Activity and outcome
Potential genotoxins
CDT (three subunits: CdtB is a functional unit, while CdtA and CdtC serve as accessory units for delivery into target cells)	Haemophilus ducreyi, Helicobacter hepaticus, Salmonella typhi. Actinobacillus actinomycetemcomitans	DNAase; DNA damage and cell cycle inhibitor[56,57]
Cytolethal distending toxin B	Salmonella typhi	DNAase activity, genotoxic by creating DNA lesions[58]
Colibactin	Escherichia coli	Mechanism unknown[59]
Potential pro-carcinogenic toxins
Pasturella multocida toxin	Pasturella multocida	Modifies Gq proliferation[60]
CagA	Helicobacter pylori	Binds to SHP2 and c- Met cells scattering[61]
Vacuolating cytotoxin A	Helicobacter pylori	Upregulation of VEGF expression (seems to depend on the activation of EGFR, MAP kinase and COX-2 mediated)
Bacteroides fragilis toxin	Bacteroides fragilis	Cleaves E- cadherin proliferation[62]
Cytotoxic necrotizing factor-1	Escherichia coli, Shigella dysenteriae, Campylobacter jejuni and Salmonella typhi, Helicobacter hepaticus, Actinobacillus actinomycetemcomitans	Modifies Rho family proteins, inflammation and inhibition of cell cycle, blocks cytokines[39]
Cycle inhibiting factor	Escherichia coli	Inhibit cell cycle at G2-M transition[63]
MAP	Citrobacter rodentium	Multifunctional effectors protein that target host cell mitochondria implicated in the disruption of epithelial barrier function both in vitro and in vivo[64]
VEGF	Bartonella species	Angiogenesis and proliferation[65]

MAP: Mitochondrial associated protein; VEGF: Vascular endothelial growth factor; EGFR: Epidermal growth factor receptor.