Fig. 7: 6PGD inhibition decreases the immunosuppressive function of human myeloid suppressor cells; a predictive risk factor for breast cancer outcome.

A Kaplan‒Meier estimates of distant relapse-free survival in the genomic analysis of breast cancer patients (GSE25066). The impact of PGD gene expression in entire cohort and TNBC patient samples are shown. p values were calculated using the log-rank test controlled by cohort. Patients were divided into high- and low-PGD expression groups using a higher tertile cutoff. B Gene set enrichment analysis (GSEA) of MDSC signatures comparing high and low PGD gene expression in GSE25066 cohort. Patients were divided into high- and low-PGD expression groups using a higher tertile cutoff. FDR ˂ 0.25 was considered as significant. C–G Human myeloid suppressor cells were generated from human peripheral blood mononuclear cells (PBMCs) in vitro using IL-6 (40 ng/mL) and GM-CSF (40 ng/mL) with 6AN (5 µM) or vehicle (DMSO). On Day 6, the frequency of live CD11b⁺CD33⁺ (total MDSC-like cells) (C, D), CD11b⁺CD33⁺CD14⁺CD15⁻ (monocytic-MDSC-like cells), and CD11b⁺CD33⁺CD14⁻CD15⁺ (PMN-MDSC-like cells) (E–G) cells were detected by flowcytometry. n = 3; Two-tailed t-test. H, I The expression of PD-L1 suppressive marker in human MDSC like cells (derived as in (C–G)) with 6AN (5 µM) or vehicle. PD-L1 expression was examined in CD11b⁺CD33⁺ (total MDSC like cells) (H) and CD11b⁺CD33⁺CD14⁺ monocytic cells (I). Two-tailed t-test. J Human MDSC like cells were derived as in (C–G) with 6AN (5 µM) or DMSO. CD11b⁺CD33⁺ (total MDSC-like cells) were sorted using SONY sorter and co-cultured with anti-CD3/anti-CD28 stimulated CSFE-labeled allogeneic T cells for 72 h. T cell proliferation was evaluated by flowcytometry. n = 3; Two-tailed t-test. All data are shown as mean ± SEM.