GPCRs: novel targets in cancer-associated fibroblasts

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DESCRIPTION (provided by applicant): Pancreatic cancer, in particular pancreatic ductal adenocarcinoma (PDAC), is the fourth leading cause of cancer death in the U.S. and has a 5-year survival of ~ 5%. A key contributor to this poor survival is the extensive desmoplasia (abundant fibrotic stroma) of PDAC, which can make it difficult to surgically remove the tumor and can limit access of therapeutic drugs to the tumor cells. Cancer-associated fibroblasts (CAFs), myofibroblast-like cells that produce extracellular matrix proteins, are responsible for the desmoplasia in PDAC. Pancreatic stellate cells (PSCs) and fibroblasts (PFs) are key progenitors of CAFs. Blocking the expression and activity of CAFs may be a means to improve the therapy and prognosis of PDAC. This proposal posits that G-protein-coupled receptors (GPCRs) are an important, understudied aspect of pancreatic CAFs and may be novel targets for the treatment of pancreatic cancer. GPCRs are the largest family of cell surface signaling receptors (3% of the human genome) and regulate many physiological processes. As plasma membrane proteins, GPCRs are accessible from the extracellular space; GPCRs are selectively expressed on cell types and tissues and show specificity in ligand interaction-factors that help explain why GPCRs are the targets for ~30% of current therapeutic agents albeit not in oncology. This R21 seeks to be transformative by identifying, quantifying and validating the expression of GPCRs by human pancreatic CAFs, and by assessing the therapeutic potential of GPCRs selectively expressed by CAFs (compared to PSCs and PFs). The project uses patient-derived pancreatic CAFs as a model and will use several genomic strategies: a GPCRomic approach to quantify gene expression of all non-chemosensory GPCRs, use of RNA interference knockdown GPCRs expressed by CAFs and identify the GPCRs that mediate key functional responses and gain-of-function studies by using normal pancreatic fibroblasts or pancreatic stellate cells and seeking to recapitulate the fibrotic phenotype of CAFs by enhancing expression of GPCRs in PSCs and PFs. The goal is to use genomic approaches to identify GPCRs as potential targets for the treatment of pancreatic cancer through their ability to block expression and pro-fibrotic activity of CAFs. The strategy that we will employ- GPCRomics of members of the GPCR gene family and gain of function and loss of function studies with members of this family in a human disease (in this case, in pancreatic cancer-associated fibroblasts)-is a novel one that should be readily applicable to CAFs in other cancers and to other disease settings. In addition, a further novel and clinically important aspect of this proposl is its initiation of efforts to test the idea that GPCRs on CAFs (in particular pancreatic CAFs) may be druggable targets for a disease that is in desperate need of new therapies.