Increased AKT or MEK1/2 Activity Influences Progesterone Receptor Levels and Localization in Endometriosis

Endometriosis is characterized by progesterone resistance and hyperactivity of the AKT and MAPK pathways. Kinases can cause posttranslational modifications of the progesterone receptor (PR) to influence cellular localization and protein stability. The objective of this study was to determine whether the increased AKT or MAPK kinase-1/2 (MEK1/2) activity observed in endometriotic stromal cells (OSIS) from ovarian endometriomas influences levels of PR protein. In turn, the effects of inhibiting AKT or MEK1/2 in the presence of the progestin R5020 on cell viability were investigated. Inhibiting AKT with MK-2206 or MEK1/2 with U0126 for 24 hours in the absence of R5020 increased total and nuclear PRA and PRB protein levels in OSIS but not in eutopic endometrial stromal cells from disease-free patients from disease-free patients. MK-2206 and R5020 decreased OSIS viability and increased apoptosis. Trends toward decreased volumes of sc grafted endometriosis tissues were demonstrated with MK-2206 and progesterone. Inhibition of AKT or MEK1/2 increased total and nuclear PR protein in OSIS. MK-2206 and R5020 decreased OSIS viability and increased apoptosis. The AKT and MAPK pathways may be potential molecular targets for the treatment of endometriosis.