Abstract 1311: CREB-driven tumor cell invasion and ECM remodeling promote metastasis

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) is projected to become a leading cause of cancer-related mortality, driven by its late-stage diagnosis, aggressive progression, and propensity for metastasis. Currently, no approved therapeutic effectively targets PDAC metastasis. Emerging evidence implicates extracellular matrix (ECM), and cytoskeletal dynamics are key to invasion, a pertinent contributor to PDAC metastasis. Our previous studies identified cAMP-response element binding protein 1 (CREB) as a key regulator of ECM alterations in PDAC. This study investigates the role of CREB-ROCK in regulating tumor cell invasion and metastasis at the molecular level. Methods: Expression profiles of CREB and invasion-related genes were analyzed using The Cancer Genome Atlas (TCGA) PDAC patient’s dataset. CREB expression and localization were examined in PDAC patient’s tissue microarrays (TMAs) and patient-derived xenograft (PDX) models. A novel conditional Creb knockout (Crebfl/fl) model, in an LSL-KrasG12D/+; Trp53 R172H/+; Pdx1Cre/+ (KPC) background (KPCC-/-), was generated to delineate CREB’s role in PDAC progression and metastasis. Functional studies included lentiviral creb overexpression, CRISPR/Cas9-based Creb knockout, RNA sequencing (RNA-seq), and chromatin immunoprecipitation sequencing (ChIP-seq). Metastatic lesions were assessed in genetically engineered mouse and orthotopic models (GEMMs). Matrigel invasion assays, immunohistochemistry, immunoblotting, and qPCR were used to validate the findings in vitro and in vivo. Results: TCGA analysis revealed elevated CREB and invasive gene expression in PDAC compared to normal pancreatic tissues. Immunostaining of TMAs showed increased CREB expression localized to ductal tumor cells. Creb knockout in KPCC-/- mice reduced metastatic burden, while Creb overexpression induced liver metastasis in orthotopic models. Invasion assays confirmed decreased invasiveness of tumor cells with CREB inhibition or deletion. CREB inhibition showed reduced expression of ROCK1/2, a key mediator of cytoskeletal dynamics and ECM remodeling. RNA-seq, qPCR, and ChIP-Seq analysis identified CREB as a transcriptional regulator of genes essential for invasion and ECM remodeling. CREB deletion or inhibition attenuated the expression of these targets, decreasing tumor cell invasion and metastatic potential. Conclusion: These findings establish CREB-ROCK as a central mediator of PDAC metastasis and targeting CREB-ROCK represents a promising therapeutic strategy for inhibiting invasive PDAC progression and metastasis. Citation Format: Sudhakar Jinka, Siddharth Mehra, Varunkumar Krishnamoorthy, Andrew M. Adams, Anna Bianchi, Luis N. Alberto, Yuguang Ban, Jashodeep Datta, Nipun Merchant, Nagaraj Nagathihalli. CREB-driven tumor cell invasion and ECM remodeling promote metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1311.