Abstract A44: Targeting cancer-associated fibroblasts in pancreatic ductal adenocarcinoma: Identification and characterization of therapeutic candidates

Abstract

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease with an overall survival rate of less than 5%. One of the main reasons for the poor prognosis of PDAC is thought to be due to its abundant fibrotic stromal tissue, which may act as a barrier for drug delivery, thus resulting in inefficient therapeutic treatments. Moreover, it is believed that the interactions between tumor and stromal cells play a very important role in disease progression. In this complex tumor microenvironment, cancer associated fibroblasts (CAFs) are the most significant cell type responsible for the production of extracellular matrix proteins resulting in increased stiffness of the tumor. Therefore, targeting CAFs in PDAC represents a promising therapeutic approach. In order to find attractive candidates to target the stromal tissue, we have isolated CAFs from our K-Ras driven PDAC mouse model [K-Ras+/LSLG12V;p53lox/lox;Elas-tTA/TetO-Cre strain] by cell sorting taking advantage of the high levels of expression of the PGDF Receptor-Alpha in this cell type. Next, we performed gene expression profiling by RNA sequencing comparing isolated normal pancreatic fibroblasts and CAFs. In order to complete our findings and direct our attention to tumor stromal communication we have also sequenced the transcriptome of the correspondent tumoral cells. Differential expression analysis showed significant upregulation in CAFs of a variety of functionally cancer associated cellular processes such as extracellular matrix remodeling, growth factor induced tumor growth, invasion and metastatic dissemination. Moreover, we observed a strong pro-inflammatory gene signature as well as upregulated chemokine, cytokine and adipocytokine signaling and amyloidosis in CAFs compared to normal fibroblasts through complement and coagulation cascade activation. Regulation of the inflammatory response included hyperactivity of AP1/JNK, IL6, Toll-like Receptor and NFKB pathways. However, we detected downregulation of cell cycle components, metabolic pathways and a significant decrease in the expression of p53 pathway related genes, an observation that has been already reported in CAFs associated with other cancer types. Connecting pathway mapping by Gene Set Enrichment Analysis to a novel method for generation and integration of druggable genes by cell-drug interactions offered a pool of candidates for final selection of our therapeutic approach. To further investigate the molecular mechanisms that control the fibroinflammatory stroma in PDAC, we have validated this signature by qRT-PCR in a set of CAFs and tumor samples derived from our tumor model as well as from human patients. Functional validation in vitro and in vivo of candidate genes derived from this experimental approach should lead us to identify new therapeutic targets against this deadly disease by targeting tumor-stromal cell interactions. Citation Format: Magdolna Djurec, Osvaldo Grana, David Pisano, Albert Lee, Raul Rabadan, Carmen Guerra, Mariano Barbacid. Targeting cancer-associated fibroblasts in pancreatic ductal adenocarcinoma: Identification and characterization of therapeutic candidates. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr A44.