Gene methylation in breast ductal fluid from BRCA1 and BRCA2 mutation carriers.
OBJECTIVE
Genomic alterations (including gene hypermethylation) are likely to precede the phenotypic changes associated with breast tumorigenesis. From a prospective collection of ductal lavage (DL) samples from women with a known mutation in BRCA1 or BRCA2, we have assessed promoter methylation with a comparison of results with several variables, including breast cancer (BC) outcome.


METHODS
Hypermethylation of p16, RASSF1A, twist, and RARbeta was assessed using a qualitative, real-time, nested PCR assay. Associations between methylation status and variables were tested using Fisher's exact test or logistic regression. Analyses were done at three levels: a single breast, a single duct (both over time), and each DL sample in isolation.


RESULTS
A total of 168 samples from 93 ducts in 54 breasts have been analyzed in 34 women (16 BRCA1 and 18 BRCA2 mutation carriers). A median of 2 DL was done (range, 1-5), with 7 women developing BC on study, 1 bilateral. Methylation of p16 was associated with a known BRCA1 mutation (P = 0.001, P < 0.001, and P < 0.001 for breast, duct, and sample levels, respectively) and women with a history of contralateral BC (P = 0.001 and P < 0.001 for duct and sample levels, respectively). An association was seen for women who developed BC on study and RASSF1A methylation (P = 0.001 for sample level).


CONCLUSIONS
Genetic methylation patterns could potentially be used to predict future BC risk. In addition, p16 methylation may be a predictor of BRCA1 mutation status. Further research is required to corroborate these findings.
Antill
Yoland C
YC
Victorian Breast Cancer Research Consortium Cancer Genetics Laboratory, Research Division, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia. Yoland.Antill@petermac.org
Mitchell
Gillian
G
Johnson
Sandra A
SA
Devereux
Lisa
L
Milner
Alvin
A
Di Iulio
Juliana
J
Lindeman
Geoffrey J
GJ
Kirk
Judy
J
Phillips
Kelly Anne
KA
Campbell
Ian G
IG
D000328:Adult; D014408:Biomarkers, Tumor / Q000235:genetics*; D001943:Breast Neoplasms / Q000235:genetics*; D019175:DNA Methylation / Q000235:genetics*; D005260:Female; D019398:Genes, BRCA1; D024522:Genes, BRCA2; D019942:Genes, p16; D020022:Genetic Predisposition to Disease; D006579:Heterozygote; D006801:Humans; D008875:Middle Aged; D009154:Mutation; D055966:Nipple Aspirate Fluid / Q000737:chemistry / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics; D011401:Promoter Regions, Genetic; D018168:Receptors, Retinoic Acid / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D025521:Tumor Suppressor Proteins / Q000235:genetics; D051879:Twist-Related Protein 1 / Q000235:genetics
D014408:Biomarkers, Tumor; D009687:Nuclear Proteins; C411762:RASSF1 protein, human; D018168:Receptors, Retinoic Acid; C103173:TWIST1 protein, human; D025521:Tumor Suppressor Proteins; D051879:Twist-Related Protein 1; C082925:retinoic acid receptor beta