LINC01638 promotes epithelial-to-mesenchymal transition in endometriosis epithelial cells by up-regulating RHOB via HDAC1 suppression

Research question: Is LINC01638 involved in regulation of epithelial-to-mesenchymal transition (EMT) in endometriosis? Design: A prospective patient cohort study was combined with functional experiments in the 12Z endometriosis epithelial cell line to investigate the role of LINC01638 in endometriosis. Eutopic endometrial samples were collected by curettage, and ectopic endometrial lesion samples were collected by laparoscopic surgery from 24 control patients and 41 patients with endometriosis. The phenotype of 12Z cells was assessed following LINC01638 knockdown using siRNA, performing proliferation, adhesion, migration and invasion assays, as well as assessing apoptosis and cell cycle changes with flow cytometry assays. In order to assess the relationship between LINC01638 and histone deacetylase class 1 enzyme (HDAC1), LINC01638 knockdown was combined with HDAC inhibition with the specific HDAC inhibitor romidepsin. Results: LINC01638 was up-regulated in the epithelial layer of endometriotic lesions, and LINC01638 knockdown in 12Z cells led to reduced proliferation, adhesion, migration and invasion. The reduction in proliferation was associated with increased p21 and p27 expression, and G1 phase arrest. Further analysis of LINC01638 control and knockdown cells revealed that a number of transcription factors associated with EMT are down-regulated in knockdown cells, along with the cytoskeleton regulatory gene RHOB, while HDAC1 was up-regulated. Chromatin immunoprecipitation analysis and HDAC1 inhibitory treatment combined with LINC01638 knockdown indicated that LINC01638 regulates RHOB expression via HDAC1-mediated promoter deacetylation. RHOB is up-regulated in the epithelial layer of endometriotic lesions compared with eutopic endometrium, supporting a role in the disease. Conclusions: LINC01638 is an epigenetic regulator of the pathogenesis of endometriosis, promoting proliferation and EMT of endometriotic lesions.