Combination CAF/myeloid targeting for pancreatic cancer therapy

• Applicant: Dr. Marie Christin Hasselluhn
• Subject Area: Gastroenterology ; Hematology, Oncology ; Cell Biology
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 439440500

• Final Report Year: 2023

Final Report Abstract

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease that is projected to become the second leading cause of cancer-related death in the US and Germany by 2030. On a cellular level, PDAC is characterized by tumor cells recruiting and reprograming stromal cells, thus establishing a tumor-promoting immunosuppressive niche that allows tumor growth and progression. Stromal heterogeneity and vessel obstruction is a major challenge to overcome poor chemotherapeutic response in PDAC. However, the mechanisms behind stromal reprograming in PDAC remain elusive. Previous studies identified tumor cell-secreted Sonic Hedgehog (SHH) as an important paracrine signaling factor implicated in many phenotypes in the pancreatic tumor microenvironment. Interrupting aberrant SHH signaling in genetically modified mouse models of PDAC resulted in decreased cancer-associated fibroblast (CAF) proliferation, tumor cell dedifferentiation, influx of myeloid cells, and increased vessel growth. Importantly, receptors necessary to perceive respective SHH signals are only expressed on CAFs. Attempts to recreate these complex phenotypes using in vitro co-culture experiments were futile, hinting at a larger paracrine cascade at play. Here we established a novel ex vivo platform maintaining the cellular heterogeneity and spatial resolution of a naturally grown tumor microenvironment. Tumor explants derived from a genetically engineered mouse model of PDAC or of human PDAC origin enable us to study complex phenotypes in a medium-throughput system. As a proof-of-concept, we traced the paracrine cascade from tumor cell-derived SHH over WIF1-secreting CAFs to abrogated VEGF signaling, explaining how interfering with downstream SHH signaling leads to increased vessel growth. The in vivo phenotype was successfully recapitulated ex vivo using murine and human PDAC explants. Computational analyses based on single cell RNA sequencing (scRNA-seq) in conjunction with experimental approaches elucidated involved cell types and relevant signaling factors. Based on this study, we further aim to elucidate how CAFs suppress expansion of the myeloid population within the pancreatic tumor microenvironment. Both stromal populations are main contributors to local immunosuppression, suppressing cytotoxic T cell invasion, proliferation, and activity. By using tumor explants in combination with scRNA-seq analyses, we aim to identify the paracrine factors involved in CAF-myeloid cell communication, the respective myeloid subset expanding upon CAF depletion, and how dual CAF/myeloid targeting can be exploited as a novel strategy to effectively treat PDAC patients.

Publications

• Abstract PR-014: Hedgehog represses angiogenesis in PDAC through a paracrine cascade mediated by Wif1. Cancer Research, 81(22_Supplement), PR-014-PR-014.
  Hasselluhn, Marie C.; Decker, Amanda R.; Garcia, Alvaro Curiel; Maurer, Carlo; Thomas, Dafydd & Olive, Kenneth P.
  
• Abstract 3648: Hedgehog represses angiogenesis in PDAC through a paracrine cascade mediated by Wif1. Cancer Research, 82(12_Supplement), 3648-3648.
  Hasselluhn, Marie C.; Decker, Amanda R.; Garcia, Alvaro Curiel; Maurer, Carlo; Thomas, Dafydd H. & Olive, Kenneth P.
  
• “Tumor Explants Elucidate a Cascade of Paracrine SHH, WNT, and VEGF Signals Driving Pancreatic Cancer Angiosuppression”.
  Hasselluhn, Marie C.; Decker-Farrell, Amanda R.; Vlahos, Lukas; Thomas, Dafydd H.; Curiel-Garcia, Alvaro; Maurer, H. Carlo; Wasko, Urszula N.; Tomassoni, Lorenzo; Sastra, Stephen A.; Palermo, Carmine F.; Dalton, Tanner C.; Ma, Alice; Li, Fangda; Tolosa, Ezequiel J.; Hibshoosh, Hanina; Fernandez-Zapico, Martin E.; Muir, Alexander; Califano, Andrea & Olive, Kenneth P.