| 2560 Promoter Hypermethylation Quantification in Oral Dysplasia and Cancer | ||
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C.T. VIET1, S. LIM1, R. JORDAN1, and B.L. SCHMIDT2, 1University of California - San Francisco, USA, 2University of California San Francisco, USA Background: Promoter hypermethylation, a major mechanism in silencing cancer-associated genes, is potentially an early diagnostic marker for oral cancer. Saliva is an ideal diagnostic fluid because of ease of collection. However, to date there have been no studies quantifying promoter hypermethylation in the saliva of oral dysplasia and cancer patients. Objective: To quantitatively analyze promoter hypermethylation for five genes (p15, p16, MGMT, E-cadherin, and APC) using tissue and saliva from 3 groups of patients: normal, dysplasia, and cancer. To determine the correlation between saliva and tissue promoter hypermethylation. Methods: Saliva was collected from 11 oral cancer, 3 oral dysplasia and 5 normal subjects. Methylight, a fluorescence based real-time PCR technique, was used to quantify DNA methylation at the loci of interest in the samples. The percentage of fully methylated molecules at the locus of interest, indicated as PMR (percentage of methylated reference), was calculated for each sample and compared to normal. Cancer and dysplasia saliva samples with a PMR higher than the normal threshold were classified as hypermethylated. Results: Hypermethylation of >1 genes was demonstrated in the saliva of 11/14 samples; >2 genes in 8/14 samples; >3 genes in 3/14 and > 4 genes in 2/14. Hypermethylation status between saliva and tissue samples matched at 88%, 63%, 63%, 50%, and 38% for p16, p15, E-cadherin, APC, MGMT, respectively, with a mean correlation of 60%. Conclusions: We report for the first time quantitative analysis of promoter hypermethylation in the saliva and tissue of oral dysplasia and cancer patients. Promoter hypermethylation in at least one gene was detected in 79% of saliva samples with a high correlation between tissue and saliva, which makes detection of promoter hypermethylation in saliva as a promising early marker for oral dysplasia and cancer. Support: NIDCR K12 DE14609, NIDCR DE017249-01, NCI CA095231 | ||
| Seq #267 - Junior Category 10:45 AM-12:00 PM, Saturday, March 24, 2007 Ernest N. Morial Convention Center Exhibit Hall I2-J | ||
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