Deficiencies in mouse Myh and Ogg1 result in tumor predisposition and G to T mutations in codon 12 of the K-ras oncogene in lung tumors.
Oxidative DNA damage is unavoidably and continuously generated by oxidant byproducts of normal cellular metabolism. The DNA damage repair genes, mutY and mutM, prevent G to T mutations caused by reactive oxygen species in Escherichia coli, but it has remained debatable whether deficiencies in their mammalian counterparts, Myh and Ogg1, are directly involved in tumorigenesis. Here, we demonstrate that deficiencies in Myh and Ogg1 predispose 65.7% of mice to tumors, predominantly lung and ovarian tumors, and lymphomas. Remarkably, subsequent analyses identified G to T mutations in 75% of the lung tumors at an activating hot spot, codon 12, of the K-ras oncogene, but none in their adjacent normal tissues. Moreover, malignant lung tumors were increased with combined heterozygosity of Msh2, a mismatch repair gene involved in oxidative DNA damage repair as well. Thus, oxidative DNA damage appears to play a causal role in tumorigenesis, and codon 12 of K-ras is likely to be an important downstream target in lung tumorigenesis. The multiple oxidative repair genes are required to prevent mutagenesis and tumor formation. The mice described here provide a valuable model for studying the mechanisms of oxidative DNA damage in tumorigenesis and investigating preventive or therapeutic approaches.
Xie
Yali
Y
Department of Microbiology, Immunology, and Molecular Genetics and the Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA.
Yang
Hanjing
H
Cunanan
Cristina
C
Okamoto
Kimberly
K
Shibata
Darryl
D
Pan
Janet
J
Barnes
Deborah E
DE
Lindahl
Tomas
T
McIlhatton
Michael
M
Fishel
Richard
R
Miller
Jeffrey H
JH
D000818:Animals; D003062:Codon / Q000235:genetics; D004249:DNA Damage; D045647:DNA Glycosylases / Q000172:deficiency* / Q000235:genetics; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics; D005260:Female; D011905:Genes, ras / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology; D008223:Lymphoma / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D051718:MutS Homolog 2 Protein; D010051:Ovarian Neoplasms / Q000235:genetics; D010084:Oxidation-Reduction; D017354:Point Mutation; D011518:Proto-Oncogene Proteins / Q000172:deficiency / Q000235:genetics
D003062:Codon; D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D045647:DNA Glycosylases; C485990:Ogg1 protein, mouse; C061738:mutY adenine glycosylase; C497172:MSH2 protein, human; C497173:Msh2 protein, mouse; D051718:MutS Homolog 2 Protein