Antitumor Activities of 2-Methoxyestradiol on Cervical and Endometrial Cancers In Vitro and In Vivo

2-Methoxyestradiol (2-ME), a metabolite of 17β-estradiol, is a potent antitumor and antiangiogenesis agent in vitro and in vivo. This study aimed to investigate the effects of 2-ME on human cervical and endometrial cancers in vitro and in vivo. Human cervical cancer HeLaS3 cells, endometrial cancer HEC-1-A and RL-95-2 cells, and severe combined immune deficient (SCID) mice were used. On cervical cancer HeLaS3 cells, 2-ME inhibited the cell growth which is accompanied by apoptosis via iNOS pathway and by G2/M cell cycle arrest. 2-ME had slight effects on normal cervical epithelial cells. In vivo on SCID mice, 2-ME (75 mg/kg p.o.) inhibited the growth of human cervical carcinoma by 34% (p < 0.05) and showed slight side effects to liver and spleen. On human endometrial cancer cells (HEC-1-A and RL-95-2 cells), 2-ME inhibited the growth by blocking cell cycle progress in S- and G2/M-phase in both cell types, and by inducing apoptosis in HEC-1-A cells and by causing necrosis in RL-95-2 cells. 2-ME had no effects on normal endometrial cells. The apoptotic effect, in HEC-1-A cells, was prevented by iNOS-inhibitor 1400W and eliminated by Caspase-inhibitor Z-VAD-FMK. The necrosis, on RL-95-2 cells, was due to a severe disruption of the mitochondrial membrane potential. Unfortunately, 2-ME had no significant effects on endometrial cancer xenografts. It showed slight toxicity to liver, spleen and proliferative effect on uterus. In conclusion, 2-ME inhibits the growth of human cervical and endometrial cancer cells in vitro. However, a weaker anti-tumor effect was observed in our animal model and 2-ME was slightly toxic to liver and spleen. Considering the proliferative effect on uterus, 2-ME might not be a suitable therapeutic agent in gynecological tumors