SAT-134 Gene Expression in Response to Retinoids and Estrogen Suggests the Diversity of Cellular Environment and Cell Characteristics in Endometriosis Lesions

Abstract Disclosure: M. Izawa: None. Y. Azuma: None. F. Tqniguchi: None. [Background]Endometriosis has been accepted as an estrogen-dependent disease, and the estrogen environment in endometriotic lesions has been proposed as a major background of the pathophysiology. The hormonal therapy targeting the reduction of estrogen has been employed to reduce the endometriosis-associated symptoms. However, patients do not always exhibit the expected response to the medication. In the hope of overcoming this situation, we focused on retinoids, which have been known to induce an antiproliferative activity in tumors, as molecular tools.[Objective]We evaluated the antiproliferative activity of retinoids in endometriotic stromal cells (ESCs) and subsequently examined the effect of estrogen on the activity. In parallel, we performed gene expression analysis as a clue to investigate the molecular background. [Methods]Preparation of ESCs: Institutional Review Boards approved this project. The chocolate cyst lining in the ovaries of patients with endometriosis was the source of endometriotic tissues. ESCs were collected from the endometriotic tissues. Cell proliferation assay: ESCs were treated with all-trans retinoic acid (ATRA), selective RAR modulators (sRARMs), RARγ antagonist, and 17β-estradiol (E2). The relative number of viable cells was estimated using the WST-8 assay.RNA-seq analysis: Total cellular RNAs from ESCs treated with 2.5 uM ATRA in the presence or absence of 10 nM E2 for 15 hours were prepared for polyA+ selected library and the strand-specific RNA-seq. Differentially expressed genes with p-values < 0.05 and log2 fold changes > 1 were extracted as responsive genes.[Results]Effect of retinoids and estrogen on cell proliferation: Cell proliferation was significantly decreased in the presence of ATRA. Among sRARMs tested, RARγspecific CD437 reduced cell proliferation. The antiproliferative activity of ATRA was abolished in the presence of RARγ antagonist MM11253. Among the five ESCs tested, the antiproliferative activity of ATRA in two cells was abrogated in the presence of E2. Effects of ATRA and E2 on gene expression:RNA-seq analysis was performed using the E2-responsive ESCs described above. Responsive genes were classified into three groups depending on their characteristics of expressions: ATRA-responsive genes abrogated in the presence of E2, ATRA-responsive genes without the influence of E2, and newly upregulated and downregulated genes in response to ATRA and E2. Among ATRA-responsive genes that disappeared in the presence of E2, cell proliferation-related genes were included but varied among cells.Conclusion The antiproliferative activity of retinoids may improve the hormonal therapy in endometriosis. The observation that cell proliferation and gene expression in response to retinoids and E2 varied depending on cells suggests the diversity of cellular environment and cell characteristics in endometriosis lesions. Presentation: Saturday, July 12, 2025