Inhibition of cell death in human mammary epithelial cells by the cooked meat-derived carcinogen 2-amino-1-methyl-6-phenylimidazo[4, 5-b]pyridine.
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a mammary gland carcinogen present in the human diet in cooked meat. To examine if PhIP and its reactive metabolite N-hydroxy-PhIP inhibit apoptosis in human mammary epithelial MCF-10A cells, confluent cultures deprived of serum and growth factors were incubated for 24 h with either compound. The percentages of dead cells (mean +/- SEM, n = 3) as measured by trypan blue exclusion were 5.7 +/- 0.6, 3.4 +/- 0.3, 2.7 +/- 0.3, and 0.2 +/- 0.003%, in control, 1 microM N-hydroxy-PhIP-, 5 microM N-hydroxy-PhIP-, and 100 microM PhIP-treated dishes, respectively. The expression of Bcl-2 and Bcl-x(L) as quantitated by Western blotting was 1.2- to 1.9-fold higher in the treated groups. PhIP-DNA adducts induced by N-hydroxy-PhIP in MCF-10A cells measured by the (32)P-postlabeling assay were low (<1 x 10(7), relative adduct labeling). No adducts were detected after incubation with PhIP. Western blot analysis indicated that PhIP increased ERK2 phosphorylation concomitant with Bcl-2. The results suggest that the inhibition of cell death in mammary epithelial cells by PhIP occurs independently of PhIP-DNA adducts and may involve enhanced signaling through the MAP kinase pathways.
Venugopal
M
M
Chemical Carcinogenesis Section, Laboratory of Experimental Carcinogenesis, Division of Basic Sciences, National Cancer Institute, Bethesda, MD 20892-4255, USA.
Agarwal
R
R
Callaway
A
A
Schut
H A
HA
Snyderwine
E G
EG
D017209:Apoptosis / Q000187:drug effects*; D001940:Breast / Q000166:cytology* / Q000187:drug effects; D002273:Carcinogens / Q000378:metabolism / Q000494:pharmacology*; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects; D016895:Culture Media, Serum-Free; D018736:DNA Adducts / Q000032:analysis / Q000235:genetics; D004847:Epithelial Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D007093:Imidazoles / Q000378:metabolism / Q000494:pharmacology*; D008460:Meat; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D011725:Pyridines / Q000378:metabolism / Q000494:pharmacology; D013997:Time Factors; D051020:bcl-X Protein
C494811:BCL2L1 protein, human; D002273:Carcinogens; D016895:Culture Media, Serum-Free; D018736:DNA Adducts; D007093:Imidazoles; D019253:Proto-Oncogene Proteins c-bcl-2; D011725:Pyridines; D051020:bcl-X Protein; C060533:2-hydroxyamino-1-methyl-6-phenylimidazo(4,5-b)pyridine; C049584:2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine; D019950:Mitogen-Activated Protein Kinase 1