Is endometrial polyp formation associated with increased expression of vascular endothelial growth factor and transforming growth factor-beta1?

Abstract

Objective: Endometrial polyp is a common cause of abnormal uterine bleeding, but the etiology and pathogenesis remain unclear. Vascular endothelial growth factor (VEGF) is angiogenic, related to thick walled vessels and transforming growth factor-beta1 (TGF-β1) is related to fibrotic tissue, which are characteristics of endometrial polyps. The primary objective of this study was to find out if endometrial polyp formation is associated with increased expression of VEGF or TGF-β1, or both. A secondary objective is to determine if the changes are related to steroid receptor expression.

Study design: This prospective study compared VEGF and TGF-β1 expression of endometrial polyps and adjacent endometrial tissue in 70 premenopausal women. The comparison of results was separately made for endometrium specimens obtained in the proliferative and secretory phases. The results were correlated with the steroid receptors (estrogen receptor and progesterone receptor) expression.

Results: The score of VEGF in glandular cells of endometrial polyps was significantly higher than the score in adjacent endometrium, both in the proliferative phase (P<0.001) and the secretory phase (P=0.03); the score of VEGF in stromal cells of endometrial polyps was significantly higher than the score in adjacent endometrium only in proliferative phase (P=0.006). The score of TGF-β1 in glandular cells of endometrial polyps was significantly higher than the score in adjacent endometrium in proliferative phase (P=0.02); whereas the score of TGF-β1 in stromal cells of endometrial polyps was significantly higher than the score in adjacent endometrium, both in the proliferative phase (P=0.006) and the secretory phase (P=0.008). There was a significant correlation between the expression of steroid receptors and VEGF and TGF-β1 (Spearman's correlation P<0.001 and P<0.05, respectively).

Conclusions: There was increased expression of TGF-β1 and VEGF in polyps compared to adjacent normal endometrial tissue. It suggested that these cytokines might play a role in endometrial polyp formation. In addition, there was a significant correlation between steroid receptor expression and VEGF and TGF-β1 expression.