Effects of hypoxia-inducible factor-1α on endometrial receptivity of women with polycystic ovary syndrome

Abstract

Embryo implantation is associated with an hypoxic endometrial microenvironment. Hypoxia-inducible factor-1α (HIF-1α) is activated under hypoxic conditions. In the present study, the expression pattern of HIF-1α in endometrial tissue was investigated and its effects on endometrial receptivity in patients with polycystic ovary syndrome (PCOS) were examined. A total of 81 patients were enrolled for in vitro fertilization and embryo transfer. They were divided into PCOS (n=40) and Control groups (n=41); both groups were further divided based on body weight (overweight and normal weight subgroups). The expressions of HIF-1α, vascular endothelial growth factor (VEGF) and glucose transporter protein (GLUT)-1 and GLUT4 were determined by reverse transcription-quantitative polymerase chain reaction and immunohistochemistry The results demonstrated that mRNA and protein expression levels of HIF-1α and VEGF in the PCOS group were significantly lower compared with expression levels in the Control group. However, there were no statistically significant differences in the expression levels of GLUT1 and GLUT4 between groups. In patients with PCOS, GLUT1 and GLUT4 were mainly localized in the nuclei and cytoplasm, but not in the cell membrane. Overweight patients had the lowest expression levels of HIF-1α, VEGF and GLUT1 expression compared with normal weight patients. In conclusion, HIF-1α may be involved in the molecular mechanisms of endometrial dysfunction in women with PCOS, particularly in those who are overweight. HIF-1α might therefore be a novel target for improving the endometrial receptivity and successful embryo implantation in PCOS women.