Loss of heterozygosity and nonsense mutation in Apc in azoxymethane-induced colonic tumours in min mice.
C57BL/6J Min/+ mice, which carry a nonsense mutation in Apc, were injected twice neonatally with 5 mg azoxymethane (AOM) /kg body weight. AOM treatment in comparison with untreated Min mice increased the incidence and number of colonic tumours from 6/14 to 22/24 (incidence) and 0.64+/-0.9 to 4.0+/-3.5 tumours per mice, respectively. Colonic tumours were analysed for loss of heterozygosity (LOH) in Apc, and 32 of the samples showed LOH whereas 14 did not. In untreated Min mice, all 8 tumours had LOH in Apc. All tumour samples from the AOM-treated Min mice were analysed for nonsense mutations between codons 686 and 1217 in the Apc gene, and one sample had a G-->A transition mutation in codon 1047. No beta-catenin mutations in the region coding for phosphorylation sites important for degradation were found. In conclusion, the main mechanism for colonic tumour induction in AOM-induced Min mice is LOH in Apc, but Apc nonsense mutations may also occur.
Møllersen
Linda
L
Department of Food Toxicology, Division of Environmental Medicine, Norwegian Institute of Public Health, Oslo, Norway.
Paulsen
Jan Erik
JE
Alexander
Jan
J
D000818:Animals; D001397:Azoxymethane; D002273:Carcinogens; D003043:Cocarcinogenesis; D018389:Codon, Nonsense; D003110:Colonic Neoplasms / Q000139:chemically induced / Q000235:genetics*; D003598:Cytoskeletal Proteins / Q000235:genetics; D005260:Female; D017491:Genes, APC / Q000502:physiology*; D020022:Genetic Predisposition to Disease; D019656:Loss of Heterozygosity; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D015534:Trans-Activators / Q000235:genetics; D051176:beta Catenin
C495267:CTNNB1 protein, mouse; D002273:Carcinogens; D018389:Codon, Nonsense; D003598:Cytoskeletal Proteins; D015534:Trans-Activators; D051176:beta Catenin; D001397:Azoxymethane