Microarray analysis of altered gene expression in ERbeta-overexpressing HEK293 cells.

Estrogen receptors (ERs), ERalpha and ERbeta, mediate estrogen actions in a broad range of target tissues. With the introduction of microarray techniques, a significant understanding has been gained regarding the interplay between the ERalpha and ERbeta in breast cancer cell lines. To gain a more comprehensive understanding of ERbeta-dependent gene regulation independent of ERalpha, we performed microarray analysis on HEK293/mock and HEK293/ERbeta cells. A total of 332 genes was identified as ERbeta-upregulated genes and 210 identified as ERbeta-downregulated genes. ERbeta-induced and ERbeta-repressed genes were involved in cell-cell signaling, morphogenesis, and cell proliferation. The ERbeta repressive effect on genes related to proliferation was further studied by proliferation assays, where ERbeta expression resulted in a significant decrease in cell proliferation. To identify primary ERbeta target genes, we examined a number of ERbeta-regulated genes using chromatin immunoprecipitation assays for regions bound by ERbeta. Our results showed that ERbeta recruitment was significant to regions associated with 12 genes (IL1RAP, TMSB4X, COLEC12, ENPP2, KLRC1, RERG, RGS16, TNNT2, CYR61, FER1L3, FAM108A1, and CYP4X1), suggesting that these genes are likely to be ERbeta primary target genes. This study has provided novel information on the gene regulatory function of ERbeta independent of ERalpha and identified a number of ERbeta primary target genes. The results of Gene Ontology analysis and proliferation assays are consistent with an antiproliferative role of ERbeta independent of ERalpha.