Up to one-third of women aged 30 -50 years have cysts in their breasts and are presumed to be at increased risk of developing breast cancer. Here we present an extensive proteomic and immunohistochemistry (IHC) study of breast apocrine cystic lesions aimed at generating specific biomarkers and elucidating the relationship, if existent, of apocrine cysts with cancer phenotype. To this end we compared the expression profiles of apocrine macrocysts obtained from mastectomies from high risk cancer patients with those of cancerous and non-malignant mammary tissue biopsies collected from the same patients. We identified two biomarkers, 15-hydroxyprostaglandin dehydrogenase and 3-hydroxymethylglutaryl-CoA reductase, that were expressed specifically by apocrine type I cysts as well as by apocrine metaplastic cells in type II microcysts, terminal ducts, and intraductal papillary lesions. No expression of these markers was observed in non-malignant terminal ductal lobular units, type II flat cysts, stroma cells, or fat tissue as judged by IHC analysis of matched non-malignant tissue samples collected from 93 high risk patients enrolled in our cancer program. IHC analysis of the corresponding 93 primary tumors indicated that most apocrine changes have little intrinsic malignant potential, although some may progress to invasive apocrine cancer. None of the apocrine lesions examined, however, seemed to be a precursor of invasive ductal carcinomas, which accounted for 81% of the tumors analyzed. Our studies also provided some insight into the origin, development, and enlargement of apocrine cysts in mammary tissue. The successful identification of differentially expressed proteins that characterize specific steps in the progression from early benign lesions to apocrine cancer opens a window of opportunity for designing and testing new approaches for pharmacological intervention, not only in a therapeutic setting but also for chemoprevention, to inhibit cyst development as both 15-hydroxyprostaglandin dehydrogenase and 3-hydroxymethylglutaryl-CoA reductase are currently being targeted for chemoprevention strategies in various malignancies.
Molecular & Cellular Proteomics 5:462-483, 2006.The human breast presents many benign lesions that involve both the glandular and stromal tissues. These include fibrocystic changes, benign breast tumors, and breast inflammatory disease (1). Fibrocystic changes affect more than 50% of women during their lifetime and are comprised of cystic dilation of ducts, apocrine metaplasia of ductal epithelium, fibrosis, adenosis, and intraductal epithelial proliferation (Ref.
and references therein).Cysts are fluid-filled sacs that usually develop in the upper half of the breast and are most common in women between 30 and 50 years of age (3). They are also found in menopausal women on hormone replacement therapy. Cysts start as a microscopic dilation of the ductules (microcyst) but can enlarge and reach sizes of a couple of centimeters in diameter (macrocysts) causing pain and discomfort due to the tens...