Molecular Biomarkers of Columnar Cell Lesions Identified by Proteomic Approaches.

Abstract

Abstract The widespread increase in the use of screening mammography has led to a significant rise in the detection and diagnosis of benign breast disease (BBD), which encompasses a wide variety of non-cancerous changes including columnar cell lesions (CCL). Epidemiologic studies provide evidence for a relationship between BBD and subsequent risk of developing breast cancer. Observational studies have reported CCL are found adjacent to areas of tubular carcinoma and ductal and lobular carcinomas in situ and recently published molecular data state that genetic abnormalities frequently found in low grade ductal carcinoma in situ are also found in CCL. All these data support the hypothesis that CCL are the earliest morphologically distinguishable precursor lesions to low grade ductal carcinoma in situ and invasive carcinoma. However, BBD is heterogeneous and there is limited understanding of the biological importance associated with the spectrum of lesions. The lack of accurate molecular-based risk categories, therefore, hinders the ability of assigning prognostic significance to benign biopsy findings. The purpose of our study was to identify putative molecular markers of cancer progression from epithelial cells of BBD lesions. Regions of ductal hyperplasia (DH) and normal breast epithelium were isolated from mastectomy specimens using laser capture microdissection and extracted proteins were analyzed through proteomic approaches. Of the 1,500 total protein spots resolved by 2-dimensional electrophoresis, 98 were differentially expressed between DH and normal breast epithelial proteomes. Twenty-two proteins or related isoforms were identified using mass spectrometry. Two proteins of particular interest, NAD(P)H: quinone oxidoreductase 1 (NQO1) and galectin-3, were further investigated by immunohistochemistry (IHC) on cases diagnosed with BBD lesions. NQO1 was expressed sporadically in overtly normal epithelial cells lining breast ducts, but was overexpressed in BBD and tumor tissues. Notably, we found that a subpopulation of DH tissues with CCL stained positively for NQO1 and negatively for galectin-3. This finding has significance because CCL can only be diagnosed morphologically and the presence of CCL in biopsy specimens may indicate a precancerous lesion. However, sectioning artifacts associated with core biopsies can hinder morphological diagnosis of CCL, thus a means to additionally identify these lesions using IHC has tremendous value. Together, immunohistochemical staining of NQO1 and galectin-3 may prove to be clinically relevant in the identification of CCL in biopsy samples. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2142.