Contribution of Granulocyte Colony-Stimulating Factor to the Acute Mobilization of Endothelial Precursor Cells by Vascular Disrupting Agents

Department of Molecular Pharmacology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
Cancer Research (Impact Factor: 9.33). 10/2009; 69(19):7524-8. DOI: 10.1158/0008-5472.CAN-09-0381
Source: PubMed


Vascular disrupting agents (VDA) cause acute shutdown of abnormal established tumor vasculature, followed by massive intratumoral hypoxia and necrosis. However, a viable rim of tumor tissue invariably remains from which tumor regrowth rapidly resumes. We have recently shown that an acute systemic mobilization and homing of bone marrow-derived circulating endothelial precursor (CEP) cells could promote tumor regrowth following treatment with either a VDA or certain chemotherapy drugs. The molecular mediators of this systemic reactive host process are unknown. Here, we show that following treatment of mice with OXi-4503, a second-generation potent prodrug derivative of combretastatin-A4 phosphate, rapid increases in circulating plasma vascular endothelial growth factor, stromal derived factor-1 (SDF-1), and granulocyte colony-stimulating factor (G-CSF) levels are detected. With the aim of determining whether G-CSF is involved in VDA-induced CEP mobilization, mutant G-CSF-R(-/-) mice were treated with OXi-4503. We found that as opposed to wild-type controls, G-CSF-R(-/-) mice failed to mobilize CEPs or show induction of SDF-1 plasma levels. Furthermore, Lewis lung carcinomas grown in such mice treated with OXi-4503 showed greater levels of necrosis compared with tumors treated in wild-type mice. Evidence for rapid elevations in circulating plasma G-CSF, vascular endothelial growth factor, and SDF-1 were also observed in patients with VDA (combretastatin-A4 phosphate)-treated cancer. These results highlight the possible effect of drug-induced G-CSF on tumor regrowth following certain cytotoxic drug therapies, in this case using a VDA, and hence G-CSF as a possible therapeutic target.

Download full-text


Available from: Gordon Rustin
  • Source
    • "Tumor cell repopulation and regrowth is often observed during the therapy-break periods between successive acute chemotherapies [15], [16]. Our previous studies demonstrated that the induction of BMDC-mediated angiogenesis, particularly CEPs, can contribute to tumor re-growth, and it is partially mediated by SDF-1 and G-CSF [11], [16], [32]. Since some of these experiments were conducted in non-tumor bearing mice, we suggested that the host response to chemotherapy promotes angiogenesis therefore contributing to tumor re-growth [33]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Tumor derived microparticles (TMPs) have recently been shown to contribute to tumor re-growth partially by inducing the mobilization and tumor homing of specific bone marrow derived pro-angiogenic cells (BMDCs). Since antiangiogenic drugs block proangiogenic BMDC mobilization and tumor homing, we asked whether TMPs from cells exposed to an antiangiogenic drug may affect BMDC activity and trafficking. Here we show that the level of VEGF-A is reduced in TMPs from EMT/6 breast carcinoma cells exposed to the anti-VEGF-A antibody, B20. Consequently, these TMPs exhibit reduced angiogenic potential as evaluated by a Matrigel plug and Boyden chamber assays. Consistently, BMDC mobilization, tumor angiogenesis, microvessel density and BMDC-colonization in growing tumors are reduced in mice inoculated with TMPs from B20-exposed cells as compared to mice inoculated with control TMPs. Collectively, our results suggest that the neutralization of VEGF-A in cultured tumor cells can block TMP-induced BMDC mobilization and colonization of tumors and hence provide another mechanism of action by which antiangiogenic drugs act to inhibit tumor growth and angiogenesis.
    Full-text · Article · Apr 2014 · PLoS ONE
  • Source
    • "This may be related to the majority of published studies being conducted in vitro. In cell culture EMT induction in response to drug treatment or to growth factor stimulation occurs over a much longer period ranging from a few days to several weeks26,30. In addition, it has also not been seen in clinical samples as these tumor samples are not collected immediately after treatment. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Epithelial to mesenchymal transition (EMT) is considered an important mechanism in tumor resistance to drug treatments; however, in vivo observation of this process has been limited. In this study we demonstrated an immediate and widespread EMT involving all surviving tumor cells following treatment of a mouse model of colorectal liver metastases with the vascular disruptive agent OXi4503. EMT was characterized by significant downregulation of E-cadherin, relocation and nuclear accumulation of β-catenin as well as significant upregulation of ZEB1 and vimentin. Concomitantly, significant temporal upregulation in hypoxia and the pro-angiogenic growth factors hypoxia-inducible factor 1-alpha, hepatocyte growth factor, vascular endothelial growth factor and transforming growth factor-beta were seen within the surviving tumor. The process of EMT was transient and by 5 days after treatment tumor cell reversion to epithelial morphology was evident. This reversal, termed mesenchymal to epithelial transition (MET) is a process implicated in the development of new metastases but has not been observed in vivo histologically. Similar EMT changes were observed in response to other antitumor treatments including chemotherapy, thermal ablation, and antiangiogenic treatments in our mouse colorectal metastasis model and in a murine orthotopic breast cancer model after OXi4503 treatment. These results suggest that EMT may be an early mechanism adopted by tumors in response to injury and hypoxic stress, such that inhibition of EMT in combination with other therapies could play a significant role in future cancer therapy.
    Full-text · Article · Aug 2013 · Cancer Medicine
  • Source
    • "There is now evidence that treatment with VDAs (e.g., Oxi4503) or certain chemotherapeutic drugs administered at the maximum tolerated dose (e.g., paclitaxel, cyclophosphamide, 5-FU) or local irradiation can rapidly induce mobilisation and subsequent tumour homing of a number of different proangiogenic BMDCs (Shaked et al, 2006; Kerbel, 2008; Shaked et al, 2008; De Palma and Lewis, 2011; Denardo et al, 2011; Welford et al, 2011), exerting in some cases prometastatic effects (Gingis-Velitski et al, 2011). Induction of several host growth factors and chemokines, such as granulocyte colony-stimulating factor (G-CSF), stromal cell-derived factor-1 (SDF-1) and osteopontin (OPN), contributes to this drug-induced BMDC mobilisation and migration to the viable tumour rim that remains after treatment (Shaked et al, 2008, 2009; Welford et al, 2011). This process promoting angiogenesis and rapid tumour regrowth affects the overall antitumour activities of the aforementioned treatments (Shaked et al, 2008, 2009; De Palma and Lewis, 2011; Denardo et al, 2011; Welford et al, 2011). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background: Administration of certain chemotherapy drugs at the maximum tolerated dose, vascular-disrupting agents (VDAs) and irradiation can induce mobilisation and tumour homing of proangiogenic bone marrow-derived cells (BMDCs). Increases in cytokines and chemokines contribute to such mobilisation that eventually promotes tumour (re)growth. NGR-TNF is a vascular-targeting agent in advanced clinical development, coupling the CNGRCG angiogenic vessel-homing peptide with tumour necrosis factor-alpha (TNF). We investigated whether NGR-TNF mobilises host BMDCs and growth factors. Methods: Blood was obtained from Lewis lung carcinoma and 4T1 tumour-bearing mice at different time points following NGR-TNF, VDA or anti-VEGFR2/flk-1 antibody treatment. Levels of circulating growth factors were assessed by ELISAs. BMDCs were characterised by FACS. Circulating endothelial progenitor cells were defined as CD45−/CD13+/flk-1+/CD117+/7AAD−, Tie2-expressing monocytes as CD45+/CD11b+/Tie2+ and myeloid-derived suppressor cells as CD45+/CD11b+/Gr1+ cells. Results: NGR-TNF decreases tumour blood vessel density-inducing apoptosis of tumour and tumour endothelial cells. Unlike VDAs, or high-dose NGR-TNF, lower doses of NGR-TNF, comparable to those used in clinical trials, neither mobilise nor recruit to the tumour site proangiogenic BMDCs or induce host growth factors. Conclusion: Low-dose NGR-TNF exerts antitumour activity without inducing proangiogenic host responses, conceivably important for preventing/overcoming resistance and designing combination therapeutic strategies.
    Full-text · Article · Jul 2013 · British Journal of Cancer
Show more