[Overexpression of estrogen receptor-related receptor alpha can stimulate estrogen receptor negative endometrial...

To investigate the role of human estrogen receptor-related receptor (ERR) alpha, a submember of orphan receptors, in the tumorigenesis of endometrial cancer.

Plasmid of pSG-ERRalpha was transfected into endometrial cancer cell lines HEC-1A, HEC-1B, and Ishikawa. Real-time quantitative RT-PCR and western blot were used to analyze the mRNA and protein expression of ERRalpha in endometrial cancer cell. Flow cytometry was used to analyze the cellular growth.

Expressions of the ERRalpha were significantly increased in the endometrial cancer cells transfected with pSG-ERRalpha plasmid; expression of the ERRalpha mRNA in HEC-1A cell was 9644.4 copies/ng, HEC-1B: 9835.3 copies/ng, and Ishikawa: 8008.6 copies/ng (P < 0.01); expression of the ERRalpha protein in HEC-1A cell was 1.128, HEC-1B: 1.104, and Ishikawa: 1.008 (P < 0.05). Flow cytometry showed over-expression of ERRalpha was accompanied by increased HEC-1A and HEC-1B cells in S and G(2)/M phase (P < 0.01), while this could not be observed in the estrogen receptor (ER) positive endometrial cancer cell line Ishikawa. Furthermore, cellular growth analysis showed that over-expression of ERRalpha induced cell growth increase of the ER negative endometrial cancer cells HEC-1A and HEC-1B (P < 0.05).

Over-expression of ERRalpha could stimulate ER negative endometrial cancer cell proliferation independent of estrogen-ER pathway.