Human endometrial tissues were obtained from 18 patients aged 34-47 years undergoing hysterectomy for benign reasons. ESCs were cultured under hypoxic condition or treated with 17¦Â-estradiol (E) and/or medroxyprogesterone acetate (MPA). The mRNA levels and production of ANGPT1, ANGPT2, and VEGF were assessed by real-time RT-PCR and ELISA, respectively. Analysis of hypoxia-inducible factor 1¦Á (HIF-1¦Á) and estrogen receptor ¦Á (ER¦Á) protein levels were evaluated by Western blot analysis.
Hypoxia reduced the mRNA expression and protein production of ANGPT-1 in ESCs, whereas those of ANGPT2 were unaffected, resulting in an increase of the ANGPT2/ANGPT1 ratio. Hypoxia induced mRNA expression and protein production of VEGF. E simultaneously induced VEGF production and suppressed ANGPT1 production, resulting in an increase of the ANGPT2/ANGPT1 ratio. MPA or E + MPA reduced ANGPT2 production and sustained the levels of ANGPT1, resulting in a decrease of the ANGPT2/ANGPT1 ratio. With regard to the interaction of E and hypoxia, E did not affect the regulation of angiogenic factors, HIF-1¦Á, and ER¦Á under hypoxic conditions.
Hypoxia and female sex hormones independently regulate the ANGPT2/ANGPT1 ratio and VEGF expression in human ESCs. These results may indicate a potential mechanism for hypoxia or female sex steroids influencing angiogenesis in the human endometrium.