Evaluation of miR-135a/b expression in endometriosis lesions

The pathogenesis of endometriosis is not clear; however, microRNAs (miRNAs/miRs) are involved in the pathogenesis. miRNAs are short noncoding RNAs involved in post-transcriptional regulation of gene expression by silencing the expression of target genes. The expression of miR-135a/b is associated with endometrial receptivity and implantation; the expression is also associated with the expression of certain genes, including homeobox protein Hox-A10 (HOXA-10). The present study investigated the expression of miR-135a/b in eutopic and ectopic endometrium tissues throughout the different phases of the menstrual cycle. Samples of ectopic endometriosis lesions and eutopic endometrium tissue from 23 patients who underwent laparoscopic surgery were obtained and analyzed. miRNA was extracted and the expression levels of miR-135a/b were determined by reverse transcription quantitative polymerase chain reaction assays using U6 as a housekeeping control. The expression levels of miR-135a and miR-135b in endometriosis lesions were decreased compared with the levels in endometrium tissue. However, miR-135a/b expression levels were increased in the secretory phase compared with the proliferative phase in endometriosis lesions. The increased expression of miR-135a/b during the secretory phase compared with the proliferative phase suggested that these genes serve a determinant role in the homeostasis of reproductive tissue. Therefore, the expression of genes may affect endometrial functioning, impairing embryo implantation.