Endothelial Protein C Receptor Function in Murine and Human Breast Cancer Development
Figure 4
Blocking EPCR alters proliferation in vitro and tumor take of MDA-MB-231 mfp cells in vivo.
A Sorted cells were stained for integrin subunits α4, α6, β1 and β4 and analyzed by FACS. EPCR+ cells are α4β1 positive whereas EPCR− cells are α4 negative, but express β1. Conversely, EPCR− cells expressed α6β4, and EPCR+ expressed α6 but not β4 integrin. B FACS-isolated EPCR+ or EPCR− cells were seeded in 48-well plates coated with CS-1 (5 µg/ml), or serum-free 805 G cell supernatant diluted 1∶2 with DMEM, and cultured in the presence of 100 µg/ml control IgG, αEPCR-1500, or αEPCR-1535 for 48 hours. Cell numbers were quantified by MTT assay (different between control IgG and αEPCR-1535, *p<0.05 ANOVA, followed by Bonferroni test, n = 3, mean±SD). C MDA-MB-231 mfp FACS-isolated EPCR+ cells (104/mouse) were injected into the mammary fat pad in matrigel containing 0.5 mg of either control IgG, non-blocking αEPCR-1500 or blocking αEPCR-1535. The blocking antibody significantly reduced tumor take (** p<0.005, Log-rank Test, n = 7 for IgG and αEPCR-1500, n = 8 for αEPCR-1535) and final tumor sizes (** p<0.005 versus control IgG, ANOVA with Bonferroni post test, mean±SD).