目的　构建hERR1高表达的乳腺癌细胞株 ,研究hERR1对乳腺癌细胞株生长活性的影响及其机制。方法　PCR构建hERR1真核表达载体 ,转染乳腺癌细胞株 ,G418筛选稳定表达细胞株 ;MTT法研究hERR1高表达株的生长速率 ;瞬时转染结合CAT活性分析 ,研究hERR1对ER转录功能的影响。结果　筛选了hERR1高表达乳腺癌细胞株 ;局部高表达的hERR1在体外抑制乳腺癌细胞株的生长 ;hERR1以剂量依赖方式抑制ER转录激活功能。结论　局部高表达hERR1可能通过与ER竞争结合ERE ,抑制ER的转录活化功能 ,从而抑制ER阳性乳腺癌细胞株的生长 Objective To construct breast cancer cell lines with high expression of hERR1 and study the effect of hERR1 on the growth activity of breast cancer cell lines and its mechanism. Methods The hERR1 eukaryotic expression vector was constructed and transfected into breast cancer cell lines. G418 cells were selected for stable expression. The growth rate of hERR1-overexpressing cells was determined by MTT assay. Transient transfection combined with CAT activity assay was used to investigate the effect of hERR1 on ER transcription . Results The hERR1-overexpressing breast cancer cell line was screened. The locally overexpressed hERR1 inhibited the growth of breast cancer cell lines in vitro. HERR1 inhibited the transcriptional activation of ER in a dose-dependent manner. Conclusion Local overexpression of hERR1 may inhibit the growth of ER-positive breast cancer cell lines by competitively binding ER with ER and inhibiting the transcriptional activation of ER