Profiling activities of transcription factors in breast cancer cell lines.

Transcription factors (TFs) are critical regulators of cell growth and differentiation, whose dysfunction is associated with many human diseases, including cancer. To facilitate the discovery of functionally altered TFs among the approximately 2,000 human TFs, we (Panomics, Inc., Fremont, CA) developed a Protein/DNA array technology that can be used to profile the activities of multiple TFs simultaneously. In this study, we applied this technology to examine the TF activities in three different breast cancer cell lines: MCF7 (estrogen receptor [ER] +, tamoxifen-sensitive), T47D (ER+, tamoxifen-resistant), and HCC1806 (ER-, tamoxifen-resistant). We compared the differences in TF activity in these cells lines following treatment with estradiol or tamoxifen. We found a number of TF activities unique to each of these cell lines. In addition to verifying previous findings, the novel findings of this study provide a more comprehensive view of the differences in the response of these cancer lines to estrogen and tamoxifen.