Tumor-infiltrating Mesenchymal Stem Cells: Drivers of the Immunosuppressive Tumor Microenvironment in Prostate Cancer?
Overview
Affiliations
Background: Prostate cancer is characterized by T-cell exclusion, which is consistent with their poor responses to immunotherapy. In addition, T-cells restricted to the adjacent stroma and benign areas are characterized by anergic and immunosuppressive phenotypes. In order for immunotherapies to produce robust anti-tumor responses in prostate cancer, this exclusion barrier and immunosuppressive microenvironment must first be overcome. We have previously identified mesenchymal stem cells (MSCs) in primary and metastatic human prostate cancer tissue.
Methods: An Opal Multiplex immunofluorescence assay based on CD73, CD90, and CD105 staining was used to identify triple-labeled MSCs in human prostate cancer tissue. T-cell suppression assays and flow cytometry were used to demonstrate the immunosuppressive potential of primary MSCs expanded from human bone marrow and prostate cancer tissue from independent donors.
Results: Endogenous MSCs were confirmed to be present at sites of human prostate cancer. These prostate cancer-infiltrating MSCs suppress T-cell proliferation in a dose-dependent manner similar to their bone marrow-derived counterparts. Also similar to bone marrow-derived MSCs, prostate cancer-infiltrating MSCs upregulate expression of PD-L1 and PD-L2 on their cell surface in the presence of IFNγ and TNFα.
Conclusion: Prostate cancer-infiltrating MSCs suppress T-cell proliferation similar to canonical bone marrow-derived MSCs, which have well-documented immunosuppressive properties with numerous effects on both innate and adaptive immune system function. Thus, we hypothesize that selective depletion of MSCs infiltrating sites of prostate cancer should restore immunologic recognition and elimination of malignant cells via broad re-activation of cytotoxic pro-inflammatory pathways.
Immunome profiling in prostate cancer: a guide for clinicians.
San-Jose Manso L, Alfranca A, Moreno-Perez I, Ruiz-Vico M, Velasco C, Toquero P Front Immunol. 2024; 15:1398109.
PMID: 39635522 PMC: 11614818. DOI: 10.3389/fimmu.2024.1398109.
Mesenchymal stem/stromal cells: dedicator to maintain tumor homeostasis.
Yao J, Sun L, Gao F, Zhu W Hum Cell. 2024; 38(1):21.
PMID: 39607530 DOI: 10.1007/s13577-024-01154-y.
Chang H, Liou Y, Sun D Tzu Chi Med J. 2024; 36(4):349-359.
PMID: 39421490 PMC: 11483098. DOI: 10.4103/tcmj.tcmj_100_24.
McClelland S, Maxwell P, Branco C, Barry S, Eberlein C, LaBonte M Cancers (Basel). 2024; 16(16).
PMID: 39199570 PMC: 11352248. DOI: 10.3390/cancers16162797.
Zhang Y, Wang C, Li J Exp Hematol Oncol. 2024; 13(1):64.
PMID: 38951845 PMC: 11218091. DOI: 10.1186/s40164-024-00532-4.