Objective: To study the function of miR-145, known to be dysregulated in endometriosis, and to identify its target genes in an in vitro endometriosis model.

Design: Experimental laboratory study.

Setting: University medical centers.

Patient(s): Primary endometrial stroma cells were derived from eutopic endometrium of three American Society for Reproductive Medicine stage III endometriosis patients and from ectopic lesions of four patients with deep infiltrating endometriosis.

Intervention(s): The human endometriotic cell line 12Z and primary eutopic and ectopic endometrial stroma cells were transiently transfected with miR-145 precursors or anti-miR-145 inhibitors and investigated for posttranscriptional regulation of predicted target genes and changes in cell behavior.

Main outcome measure(s): Predicted target expression was measured by quantitative reverse transcription-polymerase chain reaction and Western blotting, and altered cell behavior was monitored by cell proliferation assays. The 12Z cells were additionally investigated by Matrigel invasion assays, cell cycle analysis, side population analysis, and aldehyde dehydrogenase activity assays.

Result(s): In all cells investigated, miR-145 overexpression inhibited cell proliferation and induced down-regulation of FASCIN-1, SOX2, and MSI2. In 12Z cells miR-145 upregulation increased Matrigel invasiveness and reduced side population and aldehyde dehydrogenase-1 activity. Additional down-regulated targets in 12Z cells included OCT4, KLF4, PODXL, JAM-A, and SERPINE1/PAI-1. ACTG2 and TAGLN were up-regulated upon pre-miR-145 transfection. JAM-A, FASCIN-1, and PAI-I down-regulation in 12Z cells were confirmed by Western blotting.

Conclusion(s): miR-145 inhibits endometriotic cell proliferation, invasiveness, and stemness by targeting multiple pluripotency factors, cytoskeletal elements, and protease inhibitors.