Fig. 4

CXCR4 is associated with poor outcome in ER-positive BC and stimulated by insulin. A Pairwise comparison of CXCR4 expression in ER-positive breast cancer (BC) and the adjacent normal tissues of the TCGA dataset. B Kaplan–Meier plot showing the correlation between insulin receptor (IR) expression and disease-free interval (DFI) in ER-positive BC patients exhibiting CXCR4 levels above the median value. C Kaplan–Meier plot showing the correlation of CXCR4 expression with DFI in ER-positive BC patients exhibiting IR levels above the median value. mRNA (D) and protein (E) levels of CXCR4 evaluated respectively by real-time PCR and immunoblotting in BCAHC-1 cells exposed to vehicle (−) or 10 nM insulin (Ins), as indicated. In RNA experiments, values are normalized to the actin beta (ACTB) expression and presented as fold changes of mRNA expression upon treatments relative to vehicle. F Protein levels of CXCR4 in BCAHC-1 cells exposed for 8 h to vehicle or 10 nM Ins alone or in combination with 1 µM IR inhibitor OSI-906. G Immunoblot of CXCR4 from BCAHC-1 cells treated for 8 h with vehicle or 10 nM Ins alone or in combination with 2 mM metformin (Met), which was added to culture medium 18 h before the treatment with vehicle or insulin. Side panels show densitometric analysis of the blots normalized to the loading control. Results shown are representative of at least three independent experiments. (*) indicates significant differences with respect to vehicle sample (p < 0.05); (black square) indicates significant differences with respect to Insulin treated sample (p < 0.05)