Analysis of estrogen receptor isoforms and variants in breast cancer cell lines

In the present study, the expression of estrogen receptor (ER)alpha and ER beta isoforms in ER-positive (MCF7, T-47D and ZR-75-1) and ER-negative (MDA-MB-231, SK-BR-3, MDA-MB-453 and HCC1954) breast cancer cell lines was investigated. ER alpha mRNA was expressed in ER-positive and some ER-negative cell lines. ER alpha Delta 3, Delta 5 and Delta 7 spliced variants were present in MCF7 and T-47D cells; ER alpha A5 and Delta 7 spliced variants were detected in ZR-75-1 cells. MDA-MB-231 and HCC1954 cells expressed ER alpha Delta 5 and Delta 7 spliced variants. The ER beta 1 variant was expressed in all of the cell lines and the ER beta 2 variant in all of the ER-positive and some ER-negative cell lines (MDA-MB-231, MDA-MB-453 and SK-BR-3). MCF7, ZR-75-1, MDA-MB-453, HCC1954 and T-47D cells expressed ER beta 5. All cell lines expressed an ER alpha 66-kDa protein band, and some expressed the truncated 42-kDa variant. ER beta 1 was detected in all of the cell lines in addition to a 38-44 kDa variant. The results indicate that breast cancer cell lines widely used in research and reported as being ER-negative express ER alpha and/or ER beta mRNA and protein.