Evaluation of expression based markers for the detection of breast cancer cells

Introduction. Genes that are expressed in a highly tissue- or disease-specific manner provide possible targets for therapeutics, early detection of cancer, and monitoring of disease burden during and after treatment. Further, genes of this type that code for secreted or shed proteins may allow for serum detection of the product facilitating our ability to specifically detect the cancer in all circumstances. To this end, we are working towards identification and characterization of such genes that are specifically expressed in breast epithelium. In the current study, we have measured the expression of two markers that emerged from a screen of the Incyte LifeSeq Database and were subsequently shown to be highly restricted to breast epithelium termed BU101 (also called Lipophilin B) and BS106 (small mucin-like protein). These two novel markers were compared with two other candidate markers, Mammaglobin and Cytokeratin 19 (CK19). Methods. Utilizing quantitative real-time PCR, we compared the expression of these four genes in a series of 95 primary breast cancers, 9 lymph nodes from breast cancer patients, 13 lymph nodes from non-cancer patients and 10 normal breast tissues. Results. Cytokeratin was shown to be highly sensitive in detecting all breast cancers, while BU101, BS106 and Mammaglobin were more restricted. Conclusion. While no one of the these markers efficiently detects all breast cancers, a combination of two or more could achieve a very high sensitivity in assaying for circulating or occult breast cancer cells.