title: Hypoxia increases VEGF-A production by prostate cancer and bone marrow stromal cells and initiates paracrine activation of bone marrow endothelial cells.
abstract: Hypoxia develops at sites of rapid cancer growth near sites of poorly organized vasculature. Heparin binding growth factors (HBGFs) support neoangiogenesis of tumors. We examined the effect of culturing bone-targeted, metastatic C4-2B prostate cancer cells and bone stromal derived HS27a cells under hypoxic conditions on expression of vascular endothelial growth factor (VEGF) family members. A sealed chamber infused with 1% (hypoxic) or 20% (normoxic) O(2) was used. Both cell lines produced VEGF-A in normoxia, but little or no HB-EGF, another HBGF. HS27a cells produced low levels of FGF-2 and HGF, but little or none was secreted by C4-2B cells. Levels of VEGF-A in conditioned medium (CM) from both cell lines doubled when cultured in hypoxia. Similar changes in VEGF-A mRNA levels were seen. Receptor expression was unchanged by hypoxia. Changes in VEGF-A expression during hypoxia were preceded by nuclear accumulation of hypoxia inducible factor-1alpha (HIF-1alpha). Bone marrow endothelial (BME) cells express high levels of VEGFR2/flk-1, and are targets of VEGF-A induced neovascularization. BME cells proliferated in response to treatment with HS27a CM, but not C4-2B CM. BME cells formed tube-like angiogenic structures on growth factor reduced Matrigel in response to CM from HS27a or C4-2B cells. This response was greater when CM was produced under hypoxia, and was reduced by VEGF-A or FGF-2 neutralizing antibodies. We conclude that hypoxia triggers a physiologically relevant increase in VEGF-A by prostate cancer and bone marrow stromal cells which involves a paracrine loop that recruits and activates BME to support tumor neovascularization-related processes.
authors.affiliation: Department of Biological Sciences, University of Delaware, Room 326 Wolf Hall, Newark, DE 19716, USA.
authors.forename: Caroline
authors.initials: C
authors.lastname: Muir
authors.forename: Leland W K
authors.initials: LW
authors.lastname: Chung
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Carson
authors.forename: Mary C
authors.initials: MC
authors.lastname: Farach-Carson
mesh_terms: D001854:Bone Marrow Cells / Q000473:pathology*; D001859:Bone Neoplasms / Q000556:secondary; D002455:Cell Division; D015687:Cell Hypoxia / Q000502:physiology*; D045744:Cell Line, Tumor; D017931:DNA Primers; D042783:Endothelial Cells / Q000166:cytology* / Q000502:physiology*; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017154:Stromal Cells / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics*
chemical_list: D017931:DNA Primers; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D042461:Vascular Endothelial Growth Factor A