Abstract: Objective To investigate the effects of estrogen and tamoxifen on the expression of high mobility group box 1 (HMGB1) in human breast cancer cell line MCF-7. Methods MCF-7 cells were incubated with 17-beta E2 and tamoxifen at different concentrations for 4 d, respectively, with absolute ethanol as negative control. Real time RT-PCR and Western blotting were used afterward to detect the expression of HMGB1 at mRNA and protein level after different treatment to the cell line, respectively. Results Compared with ethanol control, HMGB1 mRNA and protein levels were significantly decreased when 17-beta-E2 was added at concentrations of 10-6 and 10-4 mol/L (P<0.05). And HMGB1 expression was significantly increased when tamoxifen was added at concentrations of 10-6 and 10-4 mol/L (P<0.05). Conclusion Estrogen could down-regulate the expression of HMGB1, while its antagonist tamoxifen has an opposite effect. So, HMGB1 probably has an inhibitory effect on breast neoplasms proliferation.

Key words: Breast neoplasms, High mobility group box 1, Real-time RT-PCR, Tamoxifen