Defining the role of Neural Cancer Associated Fibroblasts on Chemoresponse and Perineural Invasion in Pancreatic Ductal Adenocarcinoma

Abstract public domain (NIH RePORTER)

Project Summary Pancreatic adenocarcinoma (PDAC) is a deadly disease with a dismal 5-year survival rate of 13%. The PDAC tumor microenvironment (TME) is a dynamic tissue that is largely populated by cancer associated fibroblasts (CAFs). CAFs persist as a heterogenous group of cells that produce a range of factors capable of inducing immune evasion and chemoresistance in tumor cells, and which contribute to a dense fibrotic stroma in PDAC. Neurons represent another cellular component of the PDAC TME, the contributions from which are much less well understood. However, it is well appreciated that neurons contribute to poor prognosis through perineural invasion (PNI), a process is associated with pain, metastases and recurrence. Recently, I identified a subtype of PDAC CAFs that express an ‘axonal guidance’ gene program, which we named NeuRal CAFs or (NR+) CAFs. (NR+) CAFs are dominated by expression of neurotrophic genes, including Neuropilin 1 (NRP1) and Semaphorin 3A (SEMA3A), which suggests that they may promote neuron growth and infiltration. Further, I found that (NR+) CAFs are located near areas of PNI in patients, and (NR+) CAFs are enriched in recurrent tumors and/or after exposure to chemotherapy. Indeed, I also demonstrated that (NR+) CAFs protect PDAC organoids in patient-derived ex vivo assays. Despite the prominence of CAFs in PDAC, there is a limited understanding of their role in tumor growth, PNI, and chemoresistance. Our discovery of (NR+) CAFs, characterization of their molecular features, and the development of patient-derived models provides a novel inroad to study the importance of CAF-neuron interactions in PDAC. My central hypothesis is that (NR+) CAFs drive chemoresistance and PNI in PDAC through direct interactions with neurons and PDAC cells. In Aim 1, I will utilize chemical and genetic techniques in primary human (NR+) CAF cultures to determine the role of the CAF-tumor NRP1-SEMA3A signaling axis on tumor cell proliferation and chemoresistance. This will be through ex vivo co-cultures of patient-matched CAFs and organoids, as well as analysis of CAF secreted factors. In Aim 2, I will determine the interactions of (NR+) CAFs and neurons through co-culture systems between primary CAFs, patient derived organoid models and primary neurons. I will utilize neurite outgrowth assays and radial invasion assays to measure the influence of (NR+) CAFs on neurite outgrowth and PNI. This work will provide new insights into the functionality of (NR+) CAFs and the mechanisms with which they influence the PDAC TME, chemoresistance, and perineural invasion. These insights have the potential to identify therapeutic targets that can improve patient response to therapy and reduce pain, as well as a robust ex vivo model system that prioritizes translatability to patients .

Public health relevance public domain (NIH RePORTER)

Project Narrative Pancreatic cancer (PDAC) is a highly lethal disease, with only about 13% of patients surviving five years after diagnosis. PDAC tumors contain many cell types, including cancer-associated fibroblasts (CAFs) and neurons, which can worsen the disease, in part by helping cancer grow along nerves—a process called perineural invasion (PNI) that is still poorly understood. This project will uncover how a newly identified nerve-related group of CAFs, called (NR+) CAFs, function and how they shape the tumor environment, drive tumor growth, promote resistance to chemotherapy, and contribute to perineural invasion.