Abstract 944: The effects of GnRH-(1-5) on endometrial cancer cell lines

Abstract

Abstract The Gonadotropin-Releasing Hormone (GnRH) is a central regulator of reproductive function and behavior. In the periphery, GnRH is secreted by gynecologic tissues to exert local effects. Furthermore, GnRH is processed in the extracellular environment by the metalloendopeptidase EP24.15 to generate the bioactive metabolite, GnRH-(1-5). We have previously demonstrated that GnRH-(1-5) transactivates the epidermal growth factor receptor (EGFR) pathway to promote cell migration by binding the orphan receptor GPR101 in the Ishikawa and ECC-1 endometrial cancer cell lines. In this study, we sought to determine whether the effects of GnRH-(1-5) were dependent on the stage of the endometrial cancer. Cell lines ACI-181, ACI-52, and ACI-80 derived from endometrial cancers representative of stages 1, 2, and 3 respectively were tested in their response to GnRH-(1-5) treatment. Furthermore, the expression of GPR101 was confirmed by western blot analysis. Treatment with 100nM GnRH-(1-5) did not have significant changes in phospho-EGFR (pEGFR) levels in all ACI cell lines. However, subsequent measurement of ERK phosphorylation demonstrated that ACI-181 cells treated with GnRH-(1-5) had significantly (p < 0.05) increased levels in the pERK2 subunit but not pERK1, which parallels our initial findings in the Ishikawa cell line. No changes in pERK1/2 levels were determined in the other cell lines. To measure the effect of GnRH-(1-5) on cell migration, we implemented a wound closure assay. Interestingly, ACI-181 and ACI-52 cells had increased migration in response to GnRH-(1-5) treatment. To determine whether another pro-migratory pathway is regulated by GnRH-(1-5) in these cells, we measured TGF-β bioactivity using a cell-based assay from conditioned media of cells treated with GnRH-(1-5). We found that ACI-181 and ACI-52 cells had significantly (p<0.05) increased TGF-β bioactivity in response to GnRH-(1-5), indicating that these cells produced higher levels of bioactive TGF-β. It is likely that TGF-β and/or other growth factors may promote pro-survival and/or pro-migratory signaling cascades via an autocrine mechanism. These results further suggest that GnRH-(1-5) may exert differential effects on endometrial cancer cells that are not dependent on cancer progression. Funding Sources: This research was supported by grants from the John P. Murtha Cancer Center at Walter Reed National Military Medical Center through the Uniformed Services University and the National Science Foundation (IOS-1052288). Citation Format: Darwin O. Larco, Madelaine J. Cho-Clark, Maya Sorini, Cameron Lee, T. John Wu. The effects of GnRH-(1-5) on endometrial cancer cell lines. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 944.