Spatial distribution of tumor-associated macrophages in an orthotopic prostate cancer mouse model

Korie A Grayson; Joshua D Greenlee; Lauren E Himmel; Lauren A Hapach; Cynthia A Reinhart-King; Michael R King

doi:10.3389/pore.2024.1611586

Spatial distribution of tumor-associated macrophages in an orthotopic prostate cancer mouse model

Pathol Oncol Res. 2024 Apr 16:30:1611586. doi: 10.3389/pore.2024.1611586. eCollection 2024.

Authors

Korie A Grayson^{1

2}, Joshua D Greenlee¹, Lauren E Himmel³, Lauren A Hapach^{1

2}, Cynthia A Reinhart-King¹, Michael R King¹

Affiliations

¹ Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States.
² Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, United States.
³ Department of Pathology, Microbiology and Immunology, Translational Pathology Shared Resource, Vanderbilt University Medical Center, Nashville, TN, United States.

Abstract

Mounting evidence suggests that the immune landscape within prostate tumors influences progression, metastasis, treatment response, and patient outcomes. In this study, we investigated the spatial density of innate immune cell populations within NOD.SCID orthotopic prostate cancer xenografts following microinjection of human DU145 prostate cancer cells. Our laboratory has previously developed nanoscale liposomes that attach to leukocytes via conjugated E-selectin (ES) and kill cancer cells via TNF-related apoptosis inducing ligand (TRAIL). Immunohistochemistry (IHC) staining was performed on tumor samples to identify and quantify leukocyte infiltration for different periods of tumor growth and E-selectin/TRAIL (EST) liposome treatments. We examined the spatial-temporal dynamics of three different immune cell types infiltrating tumors using QuPath image analysis software. IHC staining revealed that F4/80+ tumor-associated macrophages (TAMs) were the most abundant immune cells in all groups, irrespective of time or treatment. The density of TAMs decreased over the course of tumor growth and decreased in response to EST liposome treatments. Intratumoral versus marginal analysis showed a greater presence of TAMs in the marginal regions at 3 weeks of tumor growth which became more evenly distributed over time and in tumors treated with EST liposomes. TUNEL staining indicated that EST liposomes significantly increased cell apoptosis in treated tumors. Additionally, confocal microscopy identified liposome-coated TAMs in both the core and periphery of tumors, highlighting the ability of liposomes to infiltrate tumors by "piggybacking" on macrophages. The results of this study indicate that TAMs represent the majority of innate immune cells within NOD.SCID orthotopic prostate tumors, and spatial density varies widely as a function of tumor size, duration of tumor growth, and treatment of EST liposomes.

Keywords: TRAIL; liposomes; pathologic analysis; prostate cancer; tumor-associated macrophages.

MeSH terms

Animals
Apoptosis
Disease Models, Animal
E-Selectin / metabolism
Humans
Liposomes*
Male
Mice
Mice, Inbred NOD*
Mice, SCID*
Prostatic Neoplasms* / immunology
Prostatic Neoplasms* / pathology
TNF-Related Apoptosis-Inducing Ligand / metabolism
Tumor Microenvironment / immunology
Tumor-Associated Macrophages* / immunology
Tumor-Associated Macrophages* / pathology
Xenograft Model Antitumor Assays

Substances

Liposomes
TNF-Related Apoptosis-Inducing Ligand
E-Selectin

Grants and funding

The author(s) declare(s) financial support was received for the research, authorship, and/or publication of this article. The Translational Pathology Shared Resource is supported by NCI/NIH Cancer Center Support Grant 5P30 CA68485-19 and the Vanderbilt Mouse Metabolic Phenotyping Center Grant 2 U24 DK059637-16. This work was funded by NIH Grant No. R01CA203991 to MK, NSF GRFP Grant Numbers 1650441 to KG and 1445197 to JG, and Alfred P. Sloan Fellowship to KG.