DCLK1-Isoform2 Alternative Splice Variant Promotes Pancreatic Tumor Immunosuppressive M2-Macrophage Polarization
Abstract
Tumor-associated M2-macrophages are one of the most abundant immunosuppressive cell types in the pancreatic ductal adenocarcinoma (PDAC) tumor microenvironment (TME). However, the molecular mechanisms responsible for the generation of M2-macrophages are unclear. Here, we demonstrated that overexpression of DCLK1-isoform2 in AsPC1 and MIA PaCa2 cells resulted in the polarization of M1-macrophages toward an M2 phenotype via secreted chemokines/cytokines. These M2-macrophages enhanced parental PDAC cell migration, invasion, and self-renewal, and this was associated with increased expression of Snail and Slug. We observed distinct expression of Dclk-isoform2, marked infiltration of M2-macrophages, and a marginal increase of CD8+ T cells in 20-week-old KPCY mice pancreas compared with 5 weeks old. Utilizing an autochthonous mouse model of pancreatic adenocarcinoma, we observed distinct immunoreactive Dclk1 and arginase1 in tissues where CD8+ T-cell infiltration was low and observed a paucity of DCLK1 and arginase1 staining where CD8+ T-cell infiltration was high. Finally, we found that DCLK1-isoform2 tumor-educated M2-macrophages inhibit CD8+ T-cell proliferation and granzyme-B activation. Inhibition of DCLK1 in an organoid coculture system enhanced CD8+ T-cell activation and associated organoid death. We conclude that DCLK1-isoform2 is a novel initiator of alternate macrophage activation that contributes to the immunosuppression observed in the PDAC TME. These data suggest that tumor DCLK1-isoform2 may be an attractive target for PDAC therapy, either alone or in conjunction with immunotherapeutic strategies.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jul 01, 2020
- Source ID
- 10.1158/1535-7163.mct-19-0776
Entities
People
- Ben Z Stanger
- Chinthalapally V. Rao
- Courtney W. Houchen
- Dongfeng Qu
- Janani Panneerselvam
- Kamille Pitts
- Michael S. Bronze
- Nathaniel Weygant
- Parthasarathy Chandrakesan
- Randal May
- William L Berry
Organizations
- National Institutes of Health
- United States Department of Defense
- University of Oklahoma Health Sciences Center
- University of Pennsylvania