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Mani R, Martin CG, Balu KE, Wang Q, Rychahou P, Izumi T, Evers BM, Suzuki Y. A Novel Protozoa Parasite-Derived Protein Adjuvant Is Effective in Immunization with Cancer Cells to Activate the Cancer-Specific Protective Immunity and Inhibit the Cancer Growth in a Murine Model of Colorectal Cancer. Cells 2024; 13:111. [PMID: 38247803 PMCID: PMC10814441 DOI: 10.3390/cells13020111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 12/31/2023] [Accepted: 01/05/2024] [Indexed: 01/23/2024] Open
Abstract
Cancer-specific CD8+ cytotoxic T cells play important roles in preventing cancer growth, and IFN-γ, in addition to IL-12 and type I interferon, is critical for activating CD8+ cytotoxic T cells. We recently identified the capability of the amino-terminus region of dense granule protein 6 (GRA6Nt) of Toxoplasma gondii, an intracellular protozoan parasite, to activate IFN-γ production of microglia, a tissue-resident macrophage population. Therefore, in the present study, we examined whether recombinant GRA6Nt protein (rGRA6Nt) functions as an effective adjuvant to potently activate cancer-specific protective immunity using a murine model of MC38 colorectal cancer (CRC). When mice were immunized with non-replicable (either treated with mitomycin C or irradiated by X-ray) MC38 CRC cells in combination with rGRA6Nt adjuvant and received a challenge implantation of replication-capable MC38 tumor cells, those mice markedly inhibited the growth of the implanted tumors in association with a two-fold increase in CD8+ T cell density within the tumors. In addition, CD8+ T cells of the immunized mice secreted significantly increased amounts of granzyme B, a key mediator of the cytotoxic activity of CD8+ T cells, and IFN-γ in response to MC38 CRC cells in vitro when compared to the T cells from unimmunized mice. Notably, the protective effects of the immunization were specific to MC38 CRC cells, as the immunized mice did not exhibit a significantly inhibited growth of EL4 lymphoma tumors. These results indicate that rGRA6Nt is a novel and effective protein adjuvant when used in immunizations with non-replicable cancer cells to potently activate the protective immunity specifically against the cancer cells employed in the immunization.
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Affiliation(s)
- Rajesh Mani
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, Lexington, KY 40536, USA; (R.M.)
| | - Chloe G. Martin
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, Lexington, KY 40536, USA; (R.M.)
| | - Kanal E. Balu
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, Lexington, KY 40536, USA; (R.M.)
| | - Qingding Wang
- Department of Surgery, University of Kentucky, Lexington, KY 40536, USA (P.R.)
- Markey Cancer Center, University of Kentucky, Lexington, KY 40536, USA
| | - Piotr Rychahou
- Department of Surgery, University of Kentucky, Lexington, KY 40536, USA (P.R.)
- Markey Cancer Center, University of Kentucky, Lexington, KY 40536, USA
| | - Tadahide Izumi
- Markey Cancer Center, University of Kentucky, Lexington, KY 40536, USA
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - B. Mark Evers
- Department of Surgery, University of Kentucky, Lexington, KY 40536, USA (P.R.)
- Markey Cancer Center, University of Kentucky, Lexington, KY 40536, USA
| | - Yasuhiro Suzuki
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, Lexington, KY 40536, USA; (R.M.)
- Markey Cancer Center, University of Kentucky, Lexington, KY 40536, USA
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