Infrequent loss of heterozygosity at adenomatous polyposis coli gene locusin Indian oral cancers

We have investigated loss of heterozygosity (LOH) of the adenomatous polypo sis coil (APC) tumor suppressor gene using polymerase chain reaction (PCR)- restriction fragment length polymorphism (RFLP) in 86 untreated oral cancer patients, using matched oral cancer tissue and corresponding peripheral bl ood cell (PBC) DNA samples. PBC from 70 normal healthy individuals, were al so analyzed for allelic distribution of APC gene. A 133 bp fragment, spanni ng exon 11 of the APC gene was amplified, and RsaI digestion of the PCR pro duct defined the alleles as either homozygous 133 bp (Rsa(-/-)) or 87 and 4 6 bp (Rsa(+/+)) fragments, and heterozygous (Rsa(+/-)) exhibiting the three fragments. Distribution of the three alleles, Rsa(-/-), Rsa(+/+), and Rsa( +/-) in the oral cancer patients was observed as 10.5, 51.1 and 38.4%; wher eas normal healthy individuals showed 11.4, 37.1 and 51.4%, respectively. I n the informative heterozygous (Rsa(+/-)) oral cancer patients, LOH was inf requent, demonstrated in two of 33 (6%) samples. Thus, the APC gene was inf requently altered by LOH at the polymorphic RsaI locus in exon 11 in the to bacco associated Indian oral cancer, unlike the smoking tobacco/alcohol ass ociated oral cancers from Western countries. (C) 2000 Elsevier Science Irel and Ltd. All rights reserved.