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

: In the present study, the expression of estrogen receptor (ER)α and ERβ 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. ERα mRNA was expressed in ER-positive and some ER-negative cell lines. ERα Δ3, Δ5 and Δ7 spliced variants were present in MCF7 and T-47D cells; ERα Δ5 and Δ7 spliced variants were detected in ZR-75-1 cells. MDA-MB-231 and HCC1954 cells expressed ERα Δ5 and Δ7 spliced variants. The ERβ1 variant was expressed in all of the cell lines and the ERβ2 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 ERβ5. All cell lines expressed an ERα 66-kDa protein band, and some expressed the truncated 42-kDa variant. ERβ1 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 ERα and/or ERβ mRNA and protein.