Prostate epithelium-derived Ets transcription factor mRNA is overexpressed in human breast tumors and is a candidate breast tumor marker and a breast tumor antigen.

PURPOSE There is a need to identify novel breast tumor-associated molecules with a potential as diagnostic/prognostic markers of breast cancer as well as targets of vaccine and drug discovery against this cancer. EXPERIMENTAL DESIGN We used a combination of digital differential display and reverse transcription-PCR (RT-PCR) methods to identify breast tumor-associated cDNAs. RESULTS It was found that prostate epithelium-derived Ets transcription factor (PDEF) and five other cDNAs occur at high frequency in the cDNA libraries from normal human breast tissue and human breast tumors. In contrast, these cDNAs are either undetectable or present at low frequencies in the cDNA libraries from other normal human tissues. RT-PCR expression analysis of PDEF showed it to be overexpressed in 14 of 20 primary human breast tumors and in one metastases tested. Also, consistent with the digital differential display data, RT-PCR analysis of PDEF expression showed highly restricted expression in normal human tissues. Furthermore, we show that PDEF transcript levels are 192-fold higher in the peripheral blood of a breast cancer patient in comparison with two normal individuals and another breast cancer patient. In contrast to PDEF, RT-PCR analysis of the expression of the other three cDNAs, including MYL5, Hs.44017, and Hs.215937, showed that these cDNAs are expressed in several normal human tissues. CONCLUSIONS These results suggest that PDEF is a breast tumor-associated cDNA and should be further evaluated for its potential as a breast tumor marker and a breast tumor antigen.