Expression data from premalignant breast cancers

Enlargement of normal terminal duct lobular units (TDLUs) by hyperplastic columnar epithelial cells is one of the most common abnormalities of growth in the adult female human breast. These hyperplastic enlarged lobular units (HELUs) are important clinically as the earliest histologically identifiable potential precursor of breast cancer. The causes of the hyperplasia are unknown but may include estrogen-simulated growth mediated by estrogen receptor alpha, which is highly elevated in HELUs and may be fundamental to their development. This study used DNA microarray technology and RNA from microdissected pure epithelial cells to learn more about changes in gene expression and molecular pathways associated with the development of HELUs from TDLUs Keywords: Identification of early cancer precursors Samples for the microarray studies were derived from 8 formalin-fixed paraffin-embedded tissue (FFPET) biopsies containing paired normal TDLUs and well-developed HELUs from non-cancerous adult female human breasts obtained within the past 3 years. Populations of nearly pure (>95%) epithelial cells were isolated from the TDLUs and HELUs in each biopsy (approximately 25,000 cells/sample) by laser capture microdissection (LCM)