A novel polyamine blockade therapy activates an anti-tumor immune response

作者：Alexander Eric T; Minton Allyson; Peters Molly C; Phanstiel Otto; Gilmour Susan K^*

来源：Oncotarget, 2017, 8(48): 84140-84152.

DOI：10.18632/oncotarget.20493

• polyamines
• difluoromethylornithine
• transport inhibitor
• immunomodulation
• tumor microenvironment

Most tumors maintain elevated levels of polyamines to support their growth and survival. This study explores the anti-tumor effect of polyamine starvation via both inhibiting polyamine biosynthesis and blocking the upregulated import of polyamines into the tumor. We demonstrate that polyamine blockade therapy (PBT) co-treatment with both DFMO and a novel polyamine transport inhibitor, Trimer PTI, significantly inhibits tumor growth more than treatment with DFMO or the Trimer PTI alone. The anti-tumor effect of PBT was lost in mice where CD4(+) and CD8(+) T cells were antibody depleted, implying that PBT stimulates an anti-tumor immune effect that is T-cell dependent. The PBT anti-tumor effect was accompanied by an increase in granzyme B+, IFN-gamma(+) CD8(+) T-cells and a decrease in immunosuppressive tumor infiltrating cells including Gr-1(+) CD11b(+) myeloid derived suppressor cells (MDSCs), CD4(+) CD25(+) Tregs, and CD206(+) F4/80(+) M2 macrophages. Stimulation with tumor-specific peptides elicited elevated antigen-specific IFN-gamma secretion in splenocytes from PBT-treated mice, indicating that PBT treatment stimulates the activation of T-cells in a tumor-specific manner. These data show that combined treatment with both DFMO and the Trimer PTI not only deprives polyamine-addicted tumor cells of polyamines, but also relieves polyamine-mediated immunosuppression in the tumor microenvironment, thus allowing the activation of tumoricidal T-cells.

• 出版日期2017-10-13
• 单位河北医科大学