Suppression of CXCL9 and CXCL10 secretion by PGE
in human breast cancer cell lines. (a) MCF-7 and MDA-MB 231 cells were exposed to 10 μM PGE2 for 30 minutes prior to addition of 50 ng/mL or 2.5 ng/mL IFN-γ, respectively (filled bars). Stimulation with IFN-γ and DMSO served as control (dashed bars). After 24 hours, supernatants were collected and CXCR3 ligand concentrations measured by ELISA. Results from at least three independent experiments are presented. In each experiment cells in at least six different wells were stimulated in parallel. In MCF-7 cells, PGE2 reduced the CXCL9 secretion to 60.7% ± 4.7% and the CXCL10 secretion to 48.3% ± 6.3%. In MDA-MB 231 cells, this inhibiton was less pronounced and reached statistical significance only for CXCL9 (77.8% ± 9.3%). (b) Representative experiment showing the time-dependence of CXCL9 release from MCF-7 (left) and MDA-MB 231 cells (right). The greatest inhibition of CXCL9 release by PGE2 (10 μM) was seen at 18 hours after stimulation in MCF-7 and at 24 hours in MDA-MB 231 cells. MCF-7 and MDA-MB 231 cells were stimulated with 50 ng/mL and 2.5 ng/mL IFN-γ, respectively.