MON-265 - Glucocorticoid Receptors Interact with KRAS, Modulate Oncogenic Signaling, and Drive Cellular Migration in Pancreatic Ductal Adenocarcinoma Cells

Pancreatic cancer is a lethal disease with a 5-year survival rate of ~13%. In the most common and lethal form, pancreatic ductal adenocarcinoma (PDA), there is overexpression of the gene encoding the glucocorticoid receptor (GR); a stress-activated steroid hormone receptor (SR) which is a known driver of other cancers (e.g. colorectal, ovarian). Previous studies demonstrated that glucocorticoids (GCs, GR ligands) promote tumor growth and metastasis in PDA. Despite these findings, the mechanism of GR in PDA remains unknown. Recent studies in lung cancer showed that GR interacts with RAS, a key driver of PDA which is an oncogenic mutated driver in 90% of PDAs. We hypothesize that GR contributes to PDA progression via interactions with oncogenic signaling components including (K)RAS and that ligand binding, post-translational modifications, and nuclear localization modulate GR actions in PDA. Here, we focus on GR-mediated migration, transcription, phosphorylation, and interactions with KRAS and other components of oncogenic signaling in PDA cell lines. First, we defined variable SR expression levels by qPCR (mRNA) and western blotting (protein) in a panel of human immortalized PDA cell lines (Aspc1, Bxpc-3, Capan-1, CFPAC, HPAFII, Hs766T, MiaPaca2, Panc1, Panc.1005). We then treated a subset of cells with dexamethasone (a GC), SR antagonists, cytokines (TGFbeta, IL-1beta, and LIF), and/or KRAS inhibitors to test the modulation of: 1. cellular migration (transwell migration assay), 2. expression of GR target genes (qPCR), 3. phosphorylation status of GR and oncogenic signaling pathway components (p38 MAP Kinase (MAPK), ERK1/2, AKT) (western blot), and 4. presence and location of GR-KRAS interactions (coimmunoprecipitation and proximity ligation assays (PLA)). GC or cytokine treatments increased migration of PDA cells, while treatment with SR antagonists (mifepristone, relacorilant) attenuated cytokine- and serum-induced migration. GCs promoted increased expression of known GR target genes including DUSP1 and SGK1. In response to ligand or cytokine treatment, cell lines exhibited phosphorylation of GR at Ser134, a stress-induced p38 MAPK consensus site that drives advanced phenotypes in triple negative breast cancer models. Finally, mutant KRAS and GR interact constitutively in cell lines. PLA demonstrated primarily cytoplasmic GR-KRAS interaction. GR modulating drugs including GCs, RU486, and Relacorilant abrogated GR-KRAS interaction. Our study demonstrates that GR signaling in PDA integrates with stress-activated signaling pathways linked to tumor aggressiveness. Future studies will focus on the regulation of GR-KRAS interactions, the effects of KRAS inhibitors on GR transcriptional activity, and their requirement for protumorigenic phenotypes. Our long-term goal is to elucidate novel paths to improved PDA screening and treatment.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*