Abstract B020: Retinoic acid produced by hepatic stellate cells facilitates Netrin-1 mediated pancreatic cancer metastasis

Abstract A hallmark of pancreatic ductal adenocarcinoma (PDAC) is its proclivity for metastasis as evidenced by the fact that 85% are stage IV at diagnosis. This highlights the need to better understand the biology of metastatic PDAC and identify novel therapies for this patient population. Axon guidance genes have been shown to be involved in PDAC progression, but their role is unclear. We have investigated the role of the axon guidance molecule Netrin-1 and its receptors Unc5b and DCC in PDAC. We found that in both murine and human samples that NTN1 expression is increased in metastatic PDAC and the quasi-mesenchymal subtype. Murine and TCGA data indicate that Unc5b is the dominant NTN1 receptor and genetic knock-down (KD) or knock-out (KO) of either Netrin-1 or Unc5b decreases migration, invasion, and cell survival in vitro and hepatic metastatic growth in vivo. The mechanism of Netrin-1 upregulation in metastatic PDAC is unknown. We found that hepatic stellate cell (HSC) secreted retinoic acid upregulates NTN1 through both an RXR/RAR and Elf mediated mechanism. To determine if NTN1 is involved in the process of HSC activation we found that recombinant NTN1 added to HSCs in vitro induced activation. We examined the livers of mice harboring orthotopic PDAC tumors using murine pancreatic cancer lines that were either NTN1 wild type (WT) or KO, and found that the NTN-expressing lines increased HSC activation providing evidence that NTN1 is important for long distance intercellular communication between primary pancreatic tumors and the pre-metastatic liver. We detected NTN1 within extracellular vesicles, and mice pre-conditioned with EVs from NTN1 KO cells demonstrated a decreased metastatic burden as compared mice preconditioned with NTN1 WT cells. Treatment of several murine PDAC models (autochthonous and metastatic) with a monoclonal antibody to NTN1 led to decreased metastases and increased survival. These studies reveal that NTN1 is upregulated in metastatic PDAC mediated by a novel mechanism that involves EVs, HSC activation and RXR/RAR signaling. These studies provide pre-clinical evidence to support a human clinical trial of anti-NTN1 therapy in PDAC. Citation Format: Crissy Dudgeon, Anthony Casabianca, Chris Harris, Igor Astsaturov, Charline Ogier, Xiaoyang Su, Jason Pitarresi, Wade Narrow, Fady Soliman, Tracy Withers, Patrick Mehlen, Darren Carpizo. Retinoic acid produced by hepatic stellate cells facilitates Netrin-1 mediated pancreatic cancer metastasis [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B020.