Fig. 6: Expansion and accumulations of MDSCs in Brca1 MT in vivo and in vitro.

a–c Migration assay of MDSCs from spleens of WT (a) and Brca1-MT (b) mice in conditional mediums (CM), including CMs from B477 cells (Ctr-B477), OE-S100a9 in B477 cells (OE-S100a9-B477), G600 cells (Ctr-G600), and G600 cells expressing S100a9 (sg-S100a9-G600). Quantification c in (a and b, Scale bar: 0.2 mm, n = 16–19 pictures from independently repeated three times, a panel: n = 18 from Ctr-B477, 17 from OE-S100a9-B477, 19 from Ctr-G600 and 17 from sg-S100a9-G600; b panel: n = 16 from Ctr-B477, 16 from OE-S100a9-B477, 17 from Ctr-G600 and 18 from sg-S100a9-G600). d–g Colony formation (d) and migrating cells (f) of RAW 264.7 cells in different condition mediums (CMs) of Ctr-B477, OE-S100a9-B477, Ctr-G600, and sg-S100a9-G600. Quantifications (e, n = 52–100 cell colony area from independently repeated three times, n = 87 cells from Ctr-B477, 100 from OE-S100a9-B477, 76 from Ctr-G600 and 52 from sg-S100a9-G600) in d and (g, n = 7 pictures in each group from independently repeated three times) in f, Scale bar: 0.2 mm. h Protein levels of S100a9, Cxcl12, Cyclin D1, and Arg1 in RAW 264.7 cells with CMs of Ctr-B477, OE-S100a9-B477, Ctr-G600, and sg-S100a9-G600 by western blotting. i, j Protein levels of S100a9, Cxcl12, pStat3, and Arg1 in RAW 264.7 cells treated with CMs from either B477 (i) or EMT6 (j) cell lines with either S100a9 protein (0.1 mg/ml) or S100a9 protein together with Tas inhibitor by western blotting. k–l The protein levels of S100a9, Cxcl12, pStat3 and Arg1 in RAW264.7 cells treated with CMs from G600 (k) and OE-S100a9-EMT6 (l) cells without or with Tas, or AMD3465, or Tas and AMD3465 together, respectively, by western blotting. m, n The populations of S100a9 positive (m) and MDSC (n) cells in both blood and tumors tissues after doxycycline (DOX) induction for 48 h in WT-DOX and MT-DOX mice by FACS analysis with antibodies of S100a9 and CD11b/Gr1(n = 4 mice/group) (FACS gating strategies see in Supplementary Fig. 8d). o, p MDSC populations from the blood of tumor-bearing mice with implantation of B477 (o) or G600 (p) cells without or with the expression of sgS100a9 by FACS analysis (n = 4 mice/group) (FACS gating strategies see in Supplementary Fig. 8e). q, r MDSC from breast tumor tissues (q) and blood samples (r) in Balb/c mice with fat pad implantation of Ctr-EMT6 cells, or OE-S100a9-EMT6 cells, or OE-Cxcl12 cells, or OE-S100a9/sgCxcl12 cells by CyTOF analysis (n = 6–10 mice in each group and randomly mixed them into 3 samples to do CyTOF analysis, q panel: 6 from Ctr, 10 from OE-S100a9, 8 from OE-Cxcl12, 8 from OE-S100a9/sgCxcl12, r panel: 6 from Ctr, 10 from OE-S100a9, 8 from OE-Cxcl12, 8 from OE-S100a9/sgCxcl12, gating strategies see in Supplementary Fig. 8a). The data are expressed as means ± SD (c, e, g, m, n, q, r) and P values determined by one-way ANOVA followed by Tukey’s multiple comparisons. The experiments were independently repeated three times with similar results (a–l). Source data are provided as a Source data file.