Abstract B125: Genomic methylation levels in white blood cell DNA among young girls

Abstract Lower levels of genomic DNA methylation in white blood cell DNA (WBC) have been observed in individuals with breast or other cancers. Genomic methylation in WBC has been also associated with risk factors for cancer in adulthood; data on the association with exposures earlier in life are limited. Using information from 31 girls 6 to 17 years of age from families enrolled in the Breast Cancer Family Registry, and 20 girls of similar age from families without breast cancer, we conducted a pilot study to examine whether genomic methylation in WBC is associated with selected breast cancer risk factors. Genomic methylation levels were measured by MethyLight for three repetitive elements (LINE1, Sat2M1 and AluM2), the luminometric methylation assay (LUMA), and LINE1-pyrosequencing. We found that age of menarche was inversely correlated with LINE1 MethyLight (r=−0.41, p=0.02) and pyrosequencing methylation (r=−0.48, p=0.01) levels. Girls with a body mass index (BMI, kg/m2) between 18.5 and 24.9 had lower methylation of LINE1 pyrosequencing compared with girls with higher or lower BMI values. Genomic methylation levels, measured by LUMA, AluM2 MethyLight, and LINE1 pyrosequencing, differed between girls with and without a family history of breast cancer. These data, if replicated in larger samples, suggest that breast cancer risk factors may be associated with genomic methylation in WBC in early life. Citation Information: Cancer Prev Res 2010;3(1 Suppl):B125.