The significance of the expression of ERRα as a potential biomarker in breast cancer

It was shown the functional crosstalk between ERRα and ERα in breast cancer, however, the biological significance of estrogen-related receptor α (ERRα) remains largely unclear. Therefore, we examined the expression of ERRα in 39 primary human breast cancer tissues and 19 matched normal tissues using RT-PCR and immunohistochemistry in the context of the aromatase, ERα and proliferation markers (c-myc, Ki-67) expression. Compared to the normal breast tissue, breast cancer tissues showed a slightly higher expression level of ERRα mRNA (mean 46.2 ± S.D. 42.0, 57.7 ± S.D. 58.7, respectively). However, ERRα mRNA levels in breast cancer tissues showed greater diversity than in normal tissues. Immunohistochemical analysis of breast cancers revealed perinuclear and cytoplasmic localization of ERRα. Our study shows that there is no correlation between ERRα and ERα expression. We demonstrated a positive correlation between ERRα and c-myc at the transcriptional level and statistically significant positive correlation between aromatase and the ERRα at protein level.It seems that ERRα could play an important role in the alternative pathway to classical estrogen receptors-dependent pathway in cell signaling. Development and use of ERRs modulators might lead in the future to design new well-tolerated and individualized therapeutic agents.