CEACAM6 is a PDEF induced gene in breast cancer

Identifying PDEF regulated genes may shed light on the mechanism by which PDEF may induce breast cancer progression. To that purpose, we have used the MCF-7 human breast tumor cell line model to identify PDEF induced genes. Briefly, PDEF expression was down regulated by shRNA in MCF-7 cells and RNA probes from PDEF-down regulated and control MCF-7 cells were used to screen the Affymetrics HG-U133A Gene Chips. This analysis found 62 genes that were induced 2-fold or higher by PDEF. Further analysis of 3 of these genes namely S100A7, CEACAM6 and B7-H4 in primary breast tumors showed CEACAM6 as a frequently elevated and co-exressed gene with PDEF in these tumors. We previously reported a role for PDEF (prostate derived Ets transcription factor) in breast tumor progression and its association with poor clinical outcome in ER+ breast cancer. To gain further insights into PDEF action in breast cancer, we down regulated PDEF expression by shRNA in MCF-7 human breast tumor cell line, and screened the HG-U133A human gene chips with probes from PDEF down-regulated and control MCF-7 cells. This analysis identified CEACAM6 as one of the genes induced by PDEF. Further analysis of CEACAM6 expression in relation to PDEF in 93 ER+ primary breast tumors showed largely concordant expression of these molecules. To our knowledge, our findings of CEACAM6 as a PDEF induced gene and their elevated co-expression in breast cancer have not been described before. Data from one replicate experiment is included as a representative example of the data obtained. HG-U133A gene chip pairs were screeened with biotinylated RNA probes from PDEF-down regulated MCF-7 cells (experimental) or from control MCF-7 cells.