Fig. 6: Reduced PGE2 production induced by shSK1 partially enhances ICI efficacy.

a Volcano plot showing proteins differentially regulated between control shRNA (shCtrl) and SK1-targeted shRNA (shSK1(1 and 2)) Yumm cells. Blue and red points represent under- and overexpressed proteins, respectively. b Sphk1 (left panel) aexpression in shCtrl (black column, n = 17 mice), shSK1(1) (white column, n = 17 mice) or shSK1(2) (gray column n = 12 mice) Yumm cells and Ptges (right panel) expression in shCtrl (black column, n = 8 mice), shSK1(1) (white column, n = 8 mice) or shSK1(2) (gray column, n = 5 mice) Yumm cells; n = 5–10 independent experiments. c Intracellular (left panel, n = 5) and extracellular (right panel, n = 4) PGE2 levels were normalized to those in shCtrl; n = 2–6 independent experiments. d Ptges (left panel, n = 5) and Sphk1 (right panel, n = 7) expression was analyzed in shCtrl(P) (dark gray columns) or shPGES (clear gray columns) Yumm cells; n = 5–6 independent experiments. e, f Mice were challenged with shCtrl(P) or shPGES cells on day 0, and then treated with isotype control antibody (iso; black lines), anti-CTLA-4 (red lines) or anti-PD-1 (blue lines). e Individual growth curves are depicted for each tumor (n = 10 mice). Insets: numbers indicate percentage of tumor-free mice at day 25. f Kaplan–Meier survival curves with log-rank test. shCtrl(P) and shPGES tumors were represented by black and white squares, respectively. g Levels of Foxp3, Tgfb1, Il10, Ccl17 and Ccl22 transcripts in shCtrl(P) (dark gray columns) or shPGES (clear gray columns) tumors (n = 5). Data, expressed as relative expression, are means ± SEM. The bottom-most and topmost horizontal lines, the lower and upper hinges, and the middle line of the boxplots indicate the minimum and maximum values, the 25th and 75th percentiles, and the median, respectively. Samples were compared using Kruskal–Wallis test with Dunn’s correction (b and c) or Mann–Whitney test (d).