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Stromal cell-derived Factor-1alpha (SDF-1alpha) stimulates the migration of bone marrow (BM) cells, similar to vascular endothelial growth factor (VEGF). We previously demonstrated that inhibition of VEGF(165) by small interfering RNA inhibited Ewing's sarcoma tumor growth, tumor vessel formation and recruitment of BM cells to the tumor. To determine the importance of BM cells in tumor vessel development, we investigated the effects of SDF-1alpha on VEGF-inhibited TC/siVEGF(7-1) Ewing's tumor neovasculature formation and growth. The effect of SDF-1alpha on CD34(+) progenitor cell chemotaxis was determined in vivo. Using a BM transplantation model with GFP(+) transgenic mice as BM donors and nude mice as recipients, we evaluated the effect of SDF-1alpha on the recruitment of BM-derived cells to VEGF(165)-inhibited TC/siVEGF(7-1) tumors, as well as its effect on neovasculature development, vessel morphology and tumor growth. SDF-1alpha stimulated the migration of CD34(+) progenitor cells to Matrigel plugs in vivo and promoted the retainment of BM-derived pericytes in close association with perfused, functional tumor vessels. Intratumor inoculation of Ad-SDF-1alpha into TC/siVEGF(7-1) tumors resulted in increased SDF-1 and PDGF-BB expression, augmented tumor growth, an increase in the number of large, lumen-bearing vascular structures, and enhanced vessel pericyte coverage, with no change in VEGF(165). SDF-1alpha stimulates BM cell chemotaxis and the association of these cells with functional tumor vessels. Furthermore, SDF-1alpha enhances tumor neovascularization and growth with no alteration in VEGF(165). Our work suggests that SDF-1-mediated vasculogenesis may represent an alternate pathway that could potentially be utilized by tumors to sustain growth and neovasculature expansion after anti-VEGF therapy., ((c) 2008 Wiley-Liss, Inc.)

Background: Ewing sarcoma (ES) is a highly vascular malignancy. It has been demonstrated that both angiogenesis and vasculogenesis contribute to the growth of ES tumors. Granulocyte-colony-stimulating factor (G-CSF), a cytokine known to stimulate bone marrow (BM) stem cell production and angiogenesis, is routinely administered to ES patients after chemotherapy. Whether ES cells and patient tumor samples express G-CSF and its receptor (G-CSFR) and whether treatment with this factor enhances tumor growth was examined., Methods: Human ES cell lines were analyzed for expression of G-CSF and G-CSFR in vitro and in vivo. Sixty-eight paraffin-embedded and 15 frozen tumor specimens from patients with ES were also evaluated for the presence of G-CSF and G-CSFR. The in vivo effect of G-CSF on angiogenesis and BM cell migration was determined. Using a TC/7-1 human ES mouse model, the effect of G-CSF administration on ES tumors was investigated., Results: G-CSF and G-CSFR protein and RNA expression was identified in all ES cell lines and patient samples analyzed. In addition, G-CSF was found to stimulate angiogenesis and BM cell migration in vivo. Tumor growth was found to be significantly increased in mice treated with G-CSF. The average tumor volume for the group treated with G-CSF was 1218 mm(3) compared with 577 mm(3) for the control group (P = .006)., Conclusions: The findings that ES cells and patient tumors expressed both G-CSF and its receptor in vitro and in vivo and that the administration of G-CSF promoted tumor growth in vivo suggest that the potential consequences of G-CSF administration should be investigated further.

Background: Increasing evidence suggests that lymphocyte recovery plays a major part in tumor control. Facilitating immune reconstitution might be a novel direction of cancer therapy. The purpose of this study was to determine if early lymphocyte recovery is an independent prognostic indicator for high-risk Ewing sarcoma outcome., Results: Data of 24 Ewing sarcoma patients were analyzed (age, 3 to 50 y; median, 16.5; male to female, 16:8). The 5-year overall survival (OS) of the total population was 47.9% [10.6 standard error (SE)]. Patients were separated into 2 groups: prolonged lymphopenia versus early lymphocyte recovery, using a threshold absolute lymphocyte count (ALC) of > or =500 cells/microL on day 15. The majority (67%; n=16) of the patients had an ALC > or =500 cells/microL, and of these 10/16 are alive with a 5-year OS of 58.7% (13.2 SE). In contrast, 33% (n=8) of patients had an ALC <500 cells/microL on day 15 and only 2/8 are alive with a 5-year OS of 25% (15.3 SE). This difference was significant (P=0.007 using the log rank test). When comparing patients with metastatic disease, patients with an ALC-15 < 500 cells/microL had a median survival of 13 months, whereas patients with an ALC-15 > or =500 cells/microL had a median survival of 29.5 months. All patients had an ALC before chemotherapy of >1000 cells/microL. The difference was significant (P value=0.001 using the log rank test). Univariate analysis of platelet counts, age, sex, and absolute neutrophil count showed no statistically significant association with OS., Conclusions: The data demonstrate that an ALC > or =500 cells/microL on day 15 of the first course of chemotherapy is an independent prognostic factor associated with superior OS in high-risk Ewing sarcoma.