Inactivation of both APC alleles in human and mouse tumors.
Germline mutations of the adenomatous polyposis coli (APC) gene lead to multiple intestinal tumors in familial adenomatous polyposis patients and in multiple intestinal neoplasia (Min) mice. Current models predict that inactivation of the remaining normal allele of a tumor suppressor gene is rate limiting for tumor formation, but this has been difficult to prove. While examination of colorectal adenomas from familial adenomatous polyposis patients identified somatic inactivating mutations of the second allele in the majority of tumors (19 of 24), the absolute requirement for an early inactivating event could not be demonstrated. In contrast, inactivation of the remaining allele of the murine APC (Apc) could be demonstrated in 100% (30 of 30) of tumors from Min mice. Moreover, inactivation was observed in the earliest recognizable phase of tumors, including some lesions containing as few as two dysplastic crypts. These results suggest that the mutation of the second APC allele is an early event in Min and familial adenomatous polyposis tumorigenesis, supporting Knudson's hypothesis.
Oncology Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231.
D B
DB
Levy
K J
KJ
Smith
Y
Y
Beazer-Barclay
S R
SR
Hamilton
B
B
Vogelstein
K W
KW
Kinzler
D011125:Adenomatous Polyposis Coli / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D003062:Codon / Q000235:genetics*; D017353:Gene Deletion; D017491:Genes, APC / Q000235:genetics*; D006801:Humans; D007580:Jejunal Neoplasms / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D021141:Nucleic Acid Amplification Techniques
D003062:Codon