title: Transforming Growth Factor-beta 1 Involved in the Pathogenesis of Endometriosis through Regulating Expression of Vascular Endothelial Growth Factor under Hypoxia.
abstract: BACKGROUND
  Endometriosis (EMs) is a common gynecological disorder characterized by endometrial-like tissue outside the uterus. Hypoxia induces the expression of many important downstream genes to regulate the implantation, survival, and maintenance of ectopic endometriotic lesions. Transforming growth factor-beta 1 (TGF-β1) plays a major role in the etiology of EMs. We aimed to determine whether TGF-β1 affects EMs development and progression and its related mechanisms in hypoxic conditions.
  
  
  METHODS
  Endometrial tissue was obtained from women with or without EMs undergoing surgery from October, 2015 to October, 2016. Endometrial cells were cultured and then exposed to hypoxia and TGF-β1 or TGF-β1 inhibitors. The messenger RNA (mRNA) and protein expression levels of TGF-β1, vascular endothelial growth factor (VEGF), and hypoxia-inducible factor-1α (HIF-1α) were measured. A Dual-Luciferase Reporter Assay was used to examine the effect of TGF-β1 and hypoxia on a VEGF promoter construct. Student's t-test was performed for comparison among groups (one-sided or two-sided) and a value of P < 0.05 was considered statistically significant.
  
  
  RESULTS
  TGF-β1, VEGF, HIF-1α mRNA, and protein expression were significantly higher in EMs tissue than that in normal endometrial tissue (t = 2.16, P = 0.042). EMs primary cultured cells exposed to hypoxia expressed 43.8% higher VEGF mRNA and protein (t = 6.84, P = 0.023). VEGF mRNA levels increased 12.5% in response to TGF-β, whereas the combined treatment of hypoxia/TGF-β1 resulted in a much higher production (87.5% increases) of VEGF. The luciferase activity of the VEGF promoter construct was increased in the presence of either TGF-β1 (2.6-fold, t = 6.08, P = 0.032) or hypoxia (11.2-fold, t = 32.70, P < 0.001), whereas the simultaneous presence of both stimuli resulted in a significant cooperative effect (18.5-fold, t = 33.50, P < 0.001).
  
  
  CONCLUSIONS
  The data support the hypothesis that TGF-β1 is involved in the pathogenesis of EMs through regulating VEGF expression. An additive effect of TGF-β1 and hypoxia is taking place at the transcriptional level.
authors.affiliation: Department of Obstetrics and Gynecology, Chinese People's Liberation Army General Hospital and Chinese People's Liberation Army Medical School, Beijing 100853; Department of Obstetrics and Gynecology, Chinese People's Liberation Army 202 Hospital, Shenyang, Liaoning 110821, China.
authors.forename: Yue-Xin
authors.initials: YX
authors.lastname: Yu
authors.affiliation: Department of Obstetrics and Gynecology, Chinese People's Liberation Army 202 Hospital, Shenyang, Liaoning 110821, China.
authors.forename: Yin-Ling
authors.initials: YL
authors.lastname: Xiu
authors.affiliation: Department of Obstetrics and Gynecology, Chinese People's Liberation Army 202 Hospital, Shenyang, Liaoning 110821, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Obstetrics and Gynecology, Chinese People's Liberation Army General Hospital and Chinese People's Liberation Army Medical School, Beijing 100853, China.
authors.forename: Ya-Li
authors.initials: YL
authors.lastname: Li
mesh_terms: D015153:Blotting, Western; D002478:Cells, Cultured; D004715:Endometriosis / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000235:genetics / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D042461:Vascular Endothelial Growth Factor A