Figure 6: The TNF inflammatory pathway affects phagocytosis of breast cancer cells through the regulation of CD47 expression.

(a) Flow cytometry analysis showing TNFR1 expression in the breast cancer line MCF7 (CD47Hi), non-tumorigenic breast line MCF10 (CD47Med) and HepG2 (CD47Lo) hepatoma cancer line shows that TNFR1 expression is higher in the MCF7 breast cancer cells. Mean values of TNFR1-FITC fluorescence are shown in blue to the right of each grey histogram. Grey histograms represent FMO controls. (b) Upper figure: A greater increase in CD47 expression is observed in MCF7 when compared to MCF10 or HepG2 cell lines after stimulation with TNF-α (green histogram). Mean values of CD47-APC are shown next to each histogram. Lower figure: Increase in CD47 transcript expression begins to occur after 8 h in MCF7 cells and after 24 h in HepG2 cells upon TNF-α stimulation. N=3 samples. Values represent mean+s.d. Student’s unpaired t-test for independent samples was performed. ***P<0.001. (c) Treating patient-derived xenografted (PDX) and primary patient (PP) breast tumour cells with TNF-α significantly increases CD47 gene expression in four out of five breast tumour samples. Values represent mean+s.d. Student’s unpaired t-test for independent samples was performed. ***P<0.001, **P<0.01, *P<0.1. NS=not significant. ER+ PR+=oestrogen and progesterone positive; TN=triple negative. (d) Upper panels: Blocking TNF-α with infliximab reduces CD47 expression regardless of TNF-α stimulation. Lower panels: Blocking TNF-α with infliximab while knocking down NFKB1 causes a greater reduction on CD47 expression regardless of TNF-α stimulation. (e) Treating MCF7 with infliximab increases phagocytosis of the cancer cells, and, to a greater extent, if infliximab is combined with CD47 blocking antibody. A more pronounced increase in phagocytosis of the cancer cells was observed for MCF7 cells that have NFKB1 knockdown and were treated with the infliximab and CD47 antibodies combined. N=6 samples. Values represent mean+s.d. ****P<0.0005, ***P<0.001, **P<0.05, *P=0.15 (upper figure), *P=0.20 (bottom figure).