Bile acids as endogenous etiologic agents in gastrointestinal cancer

Table 1 Bile acids induce DNA damage in cells of the esophagus

Cells/tissues	Bile acids that induce DNA damage	Assay for damage	Ref.
Cultured SV40-transformed, squamous esophageal epithelial cells (HET1-A) and Barrett’s associated adenocarcinoma cells (FLO-1)	DCA; also cocktail containing GCA, TCA, TCDCA	Comet assay1 for strand breaks	[18]
Cultured SV40-transformed, squamous esophageal epithelial cells (HET1-A)	DCA	Comet assay for strand breaks; evidence for oxidative mechanism involving nitric oxide	[19]
Cultured human adenocarcinoma cells (OE33)	DCA	Micronuclei assay; induction of micronuclei by DCA, reduced by antioxidants	[1520]
Biopsies from human Barrett’s esophageal metaplastic tissue	Cocktail containing DCA, GCA, TCA, GDCA, GCDCA	8-OHdG, an oxidized form of the DNA base guanine; assayed by IHC	[14]
Mouse model of esophagitis and Barrett’s esophagus	DCA (as dietary supplement; also zinc deficiency)	8-OHdG assayed by IHC	[17]

¹Comet assay, also known as the single cell gel electrophoresis assay; 8-OHdG: 8-hydroxydeoxyguanosine; IHC: Immunohistochemical assay.