Downregulation of DNA methyltransferase 3 alpha promotes cell proliferation and invasion of ectopic endometrial stromal cells in adenomyosis

Adenomyosis is a common benign gynecological condition in female reproductive tract and the detailed molecular etiology remains largely elusive. Previous studies implicated that deregulated expression of DNA (cytosine-5)-methyltransferase 3A (DNMT3A), a de novo DNA methyltransferase, might be involved in the pathogenesis of adenomyosis. Meanwhile, ectopic endometrial stromal cells (EESCs) were suggested to play crucial roles in adenomyosis. Herein, we evaluated the expression of DNMT3A protein in 36 ectopic endometriums with adenomyosis and 37 eutopic endometriums in controls with Western blotting (WB) or immunohistochemistry (IHC), we found that the expression of DNMT3A was significantly decreased in the ectopic endometriums and EESCs in adenomyosis relative to that of eutopic endometriums and EESCs in control samples, respectively. In addition, our functional assays revealed that overexpression of DNMT3A suppressed cell proliferation and invasion, while knockdown of DNMT3A enhanced cell proliferation and invasion in EESCs. Taken together, our results suggested that DNMT3A expression was decreased in ectopic endometriums and EESCs in adenomyosis, and we provided the first evidence that decreased DNMT3A expression in EESCs facilitated the development of adenomyosis via enhanced cell growth and invasion.