Fig. 5

FOXF2 confers osteomimetic features and osteotropism on breast cancer cells by direct transactivation of the BMP4/SMAD1 signaling pathway. a The protein levels of BMPs and SMADs in the indicated cells were detected by immunoblot. b Candidate FOXF2 target genes in the BMP/SMAD signaling pathway are shown. c The binding of FOXF2 to the BMP4 and SMAD1 promoters containing or lacking FOXF2-binding sequences was assessed by ChIP assays. d BMP4 and SMAD1 promoter activation in the indicated cells was assessed by dual-luciferase reporter assays. pGL3-BMP4 or pGL3-SMAD1 promoter luciferase reporter constructs containing or lacking the FOXF2-binding element were transfected into the indicated cells. e BMP reporter activation was assessed based on the fluorescence intensity of GFP. *P < 0.05 by Student’s t test. Error bars are defined as s.d. f BMP4 and SMAD1 mRNA levels in primary breast cancer tissues that developed bone-only metastasis (BOM; n = 61) or metastases in other distant organs with or without bone metastasis (NBM; n = 36) were analyzed based on the GSE2034_GSE2603 data set. g BMP4 and SMAD1 mRNA levels in metastatic tissues in bone (BM; n = 18) and in other distant organs (NBM; n = 47) were analyzed based on the GSE14020 data set. h, i Kaplan–Meier analysis of the BOMFS rate of patients with different BMP4 or SMAD1 mRNA levels (h) or combined FOXF2/BMP4 and FOXF2/SMAD1 mRNA levels (i) in primary breast cancers was performed based on the GSE2034_GSE2603 data set. *P < 0.05 and ***P < 0.001, FOXF2_high/BMP4_high vs. FOXF2_low/BMP4_low and FOXF2_high/SMAD1_high vs. FOXF2_low/SMAD1_low; ^#P < 0.05, FOXF2_high/BMP4_high vs. FOXF2_low/BMP4_high or FOXF2_high/SMAD1_high vs. FOXF2_low/SMAD1_high; ^&&P < 0.01, FOXF2_high/SMAD1_high vs. FOXF2_high/SMAD1_low