Abstract #5668: Identification of primary cilia in human breast tissue and cell lines

Primary Cilia (PC), solitary microtubule-based structures present in various types of eukaryotic cells, were recently found to be critical platforms for several signal transduction pathways. Alterations in PC-associated genes were reported to be related to certain congenital and acquired diseases. The functions of PC are cell type specific and are just beginning to be understood. Their presence and roles in the human breast are largely unknown. We sought to examine the occurrence of PC in several human breast cell lines, as well as in normal and malignant human breast tissues. Our results revealed different patterns of PC expression among human breast cell lines. By using a computer-aided quantification approach of immunofluorescence for acetylated tubulin, a marker of PC, we found a relatively high expression of PC in fibroblasts isolated from normal breast (PC present in 55% of cells) and epithelial cell lines derived from normal breast including human mammary epithelial cells (HMEC) and MCF-10A cells (in 8 -16% of cells); a much lower occurrence in MDA-MB-435 cells (in 0.7% of cells), MDA-MB-231 (in 0.2% of cells), and T-47D cells (in 0.2 % of cells); and virtually absent in other breast cancer cell lines including MDA-MB-468, SK-BR-3, ZR-75-1, BT-474 and MCF-7. We also explored the presence of PC in formalin-fixed, paraffin-embedded benign and cancerous human breast tissues by immunofluorescence. PC were readily found in benign, histological normal breast tissues, primarily in fibroblasts and mammary myoepithelial cells (identified by immunostaining for keratin 14), while rarely in luminal epithelial cells (identified by pancytokeratin staining and location). In the cancer tissues examined thus far, no primary cilia have been definitively identified in cancerous epithelial cells by immunofluorescence. These observations indicate that PC are normally present in stromal and epithelial cells of the human breast. However, their occurrence is lower in breast cancer epithelial cells, raising the possibility that loss of PC is associated with carcinogenesis. Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 5668.