Clinical significance of estrogen receptor phosphorylation

Multiple sites of phosphorylation on human estrogen receptor alpha (ER alpha) have been identified by a variety of methodologies. Now with the emerging availability of phospho-site-specific antibodies to ER alpha, the relevance of phosphorylation of ER alpha in human breast cancer in vivo is being explored. Multiple phosphorylated sites in ER alpha can be detected in multiple breast tumor biopsy samples, providing evidence of their relevance to human breast cancer in vivo. Published data suggest that the detection in primary breast tumors of phosphorylation at some sites in ER alpha is associated with a better clinical outcome while phosphorylation at other sites is associated with a poorer clinical outcome most often in patients who have been treated with tamoxifen. This suggests the hypothesis that phospho-profiling of ER alpha in human breast tumors to establish an 'ER alpha phosphorylation code', may be a more accurate marker of prognosis and/or response to endocrine therapy in human breast cancer.