[Effects of estrogen receptor beta on proliferation of ovarian clear cell adenocarcinoma ES-2 in vitro and in vivo].

Objective: To investigate the involvement of estrogen receptor (ER) beta in the proliferation of ovarian clear cell adenocarcinoma by restoring ERbeta expression in a cell line ES-2.

Methods: A plasmid with full length ERbeta cDNA, pRSV-ERbeta and its negative vector control pRSV were introduced into ES-2. The cells transfected were named according to the plasmids: ES-pRSV, ES-pRSV-ERbeta. RT-PCR and western blot were used to detect the expression of ERbeta in ES-2, ES-pRSV and ES-pRSV-ERbeta cells. The growth activities of cells in vitro were detected by methyl thiazolyl tetrazolium (MTT) assay, and in vivo growth in nude mice was also observed. Flow cytometry was performed to show the change of cell cycles.

Results: The ES-pRSV-ERbeta cells were identified with ERbeta mRNA and protein expression. The growth activities of ES-pRSV-ERbeta were inhibited in vitro. In MTT analysis, the values of ES-2, ES-pRSV, and ES-pRSV-ERbeta cells were 0.78 +/- 0.05, 0.81 +/- 0.06, and 0.53 +/- 0.07 (the third was lower compared with the former two, P < 0.01). In vivo, the volume of transplants of ES-pRSV-ERbeta cells in mice, (2868 +/- 879) mm(3) was smaller than that in ES-2, (3603 +/- 724) mm(3), and in ES-pRSV, (3913 +/- 624) mm(3) (P < 0.05). The S phase ratios of the cell cycle of ES-2, ES-pRSV, and ES-pRSV-ERbeta were (37 +/- 9)%, (39 +/- 10)%, and (20 +/- 5)% (P < 0.05).

Conclusions: ERbeta may play an important role in the proliferation, and DNA synthesis of ES-2. The evidence indicates ERbeta may be an inhibitor in the initiation and development of ovarian clear cell adenocarcinoma.