Androgen receptor CAG repeat lengths in ductal carcinoma in situ of breast, longest in apocrine variety

CAG repeat number in the androgen receptor (AR) has been associated with de creased prostate cancer risk, and AR expression has been found in female br east cancer, often associated with apocrine differentiation Because trinucl eotide expansion can alter gene expression and protein function, we hypothe sized that it might occur in breast neoplasms. We used a repeat expansion d etection technique to determine CAG repeat lengths in DNA from breast biops ies. Three lesion types were microdissected: fibroadenoma(48 cases), ductal carcinoma in situ (DCIS, 24 cases), and invasive mammary carcinoma (18 cas es). The maximum number of CAG repeats in either allele of each patient in these three groups was compared. Microsatellite repeat lengths in DCIS were longer than in fibroadenomas or invasive carcinomas (P = 0.017 comparing D CIS vs invasive carcinomas). Two cases of apocrine DCIS had very long repea t lengths, both exhibiting microsatellite lengths at the longest range of n ormal (32 and 33). Inherited differences in AR CAG length might influence t he transition from DCIS to invasive breast cancer, perhaps by modulating fu nction of AR in breast tissue. AR microsatellite polymorphisms could influe nce cellular differentiation in DCIS lesions, promoting formation of the ap ocrine subtype in the presence of longer CAG repeats. (C) 2000 Harcourt Pub lishers Ltd.