title: Stromal cell-derived factor-1/CXCL12 contributes to MMTV-Wnt1 tumor growth involving Gr1+CD11b+ cells.
abstract: BACKGROUND
  Histological examinations of MMTV-Wnt1 tumors reveal drastic differences in the tumor vasculature when compared to MMTV-Her2 tumors. However, these differences have not been formally described, nor have any angiogenic factors been implicated to be involved in the Wnt1 tumors.
  
  
  RESULTS
  Here, we show that MMTV-Wnt1 tumors were more vascularized than MMTV-Her2 tumors, and this correlated with significantly higher expression of a CXC chemokine, stromal cell-derived factor-1 (SDF1/CXCL12) but not with VEGFA. Isolation of various cell types from Wnt1 tumors revealed that SDF1 was produced by both tumor myoepithelial cells and stromal cells, whereas Her2 tumors lacked myoepithelial cells and contained significantly less stroma. The growth of Wnt1 tumors, but not Her2 tumors, was inhibited by a neutralizing antibody to SDF1, but not by neutralization of VEGFA. Anti-SDF1 treatment decreased the proportion of infiltrating Gr1(+) myeloid cells in the Wnt1 tumors, which correlated with a decrease in the percentage of endothelial cells. The involvement of Gr1(+) cells was evident from the retardation of Wnt1 tumor growth following in vivo depletion of these cells with an anti-Gr1-specific antibody. This degree of inhibition on Wnt1 tumor growth was comparable, but not additive, to the effect observed with anti-SDF1, indicative of overlapping mechanisms of inhibition. In contrast, Her2 tumors were not affected by the depletion of Gr1(+) cells.
  
  
  CONCLUSIONS
  We demonstrated that SDF1 is important for Wnt1, but not for HER2, in inducing murine mammary tumor and the role of SDF1 in tumorigenesis involves Gr1(+) myeloid cells to facilitate growth and/or angiogenesis.
authors.affiliation: Research Oncology, Genentech Inc, South San Francisco, California, USA.
authors.forename: Bob Y
authors.initials: BY
authors.lastname: Liu
authors.forename: Irina
authors.initials: I
authors.lastname: Soloviev
authors.forename: Peter
authors.initials: P
authors.lastname: Chang
authors.forename: John
authors.initials: J
authors.lastname: Lee
authors.forename: XiaoDong
authors.initials: X
authors.lastname: Huang
authors.forename: Cuiling
authors.initials: C
authors.lastname: Zhong
authors.forename: Napoleone
authors.initials: N
authors.lastname: Ferrara
authors.forename: Paul
authors.initials: P
authors.lastname: Polakis
authors.forename: Chie
authors.initials: C
authors.lastname: Sakanaka
mesh_terms: D000818:Animals; D039481:CD11b Antigen / Q000502:physiology*; D054377:Chemokine CXCL12 / Q000502:physiology*; D008324:Mammary Tumor Virus, Mouse / Q000502:physiology*; D051379:Mice; D009374:Neoplasms, Experimental / Q000503:physiopathology* / Q000821:virology; D042461:Vascular Endothelial Growth Factor A / Q000502:physiology; D051155:Wnt1 Protein / Q000502:physiology*
chemical_list: D039481:CD11b Antigen; D054377:Chemokine CXCL12; C515256:Cxcl12 protein, mouse; D042461:Vascular Endothelial Growth Factor A; D051155:Wnt1 Protein; C495246:Wnt1 protein, mouse