The microbial PhIP metabolite 7-hydroxy-5-methyl-3-phenyl-6,7,8,9-tetrahydropyrido[3',2':4,5]imidazo[1,2-a]pyrimidin-5-ium chloride (PhIP-M1) induces DNA damage, apoptosis and cell cycle arrest towards Caco-2 cells.
7-Hydroxy-5-methyl-3-phenyl-6,7,8,9-tetrahydropyrido[3',2':4,5]imidazo[1,2-a]pyrimidin-5-ium chloride (PhIP-M1) is a newly identified intestinal microbial metabolite from the food carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Although the mutagenic potential of the endogenous N-hydroxy PhIP derivate has been reported, the risks associated with PhIP-M1 have not yet been explored. In this work, the cytotoxic and genotoxic effects originating from PhIP-M1 were assessed in the epithelial intestinal Caco-2 cell line. PhIP-M1 significantly decreased in a time- and dose-dependent manner mitochondrial dehydrogenase activity and protein synthesis, with IC50 values of, respectively, 180+/-39.4 and 173+/-20.3 microM after 24h, and 33.8+/-3.5 and 37.3+/-10.9 microM after 72 h. Apoptosis within the concentration ranges of cytotoxicity was confirmed by morphological examination, DAPI nuclear staining and annexin V staining. PhIP-M1 provoked cell cycle arrest, characterized by a significant increase in the number of nucleoids in the G2/M phase. A dose-dependent increase in DNA damage, as quantified by the alkaline comet assay, was observed after 3h in the 50-200 microM range. Because these PhIP-M1-induced genomic and cellular events may contribute to the carcinogenicity of PhIP, the potency of the colon microbiota to bioactivate PhIP must be included in future risk assessments.
Vanhaecke
Lynn
L
Laboratory of Microbial Ecology and Technology, Faculty of Bioscience Engineering, Ghent University-UGent, Coupure Links 653, B-9000 Ghent, Belgium. Lynn.Vanhaecke@ugent.be
Derycke
Lara
L
Le Curieux
Frank
F
Lust
Sofie
S
Marzin
Daniel
D
Verstraete
Willy
W
Bracke
Marc
M
D017209:Apoptosis; D018938:Caco-2 Cells; D002273:Carcinogens / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D020552:Comet Assay; D004249:DNA Damage; D006801:Humans; D007093:Imidazoles / Q000378:metabolism* / Q000633:toxicity*; D009153:Mutagens / Q000633:toxicity*; D011743:Pyrimidines / Q000633:toxicity*
C530128:7-hydroxy-5-methyl-3-phenyl-6,7,8,9-tetrahydropyrido(3',2'-4,5)imidazo(1,2-a)pyrimidin-5-ium; D002273:Carcinogens; D007093:Imidazoles; D009153:Mutagens; D011743:Pyrimidines; C049584:2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine