title: Vasculogenic mimicry of HT1080 tumour cells in vivo: critical role of HIF-1α-neuropilin-1 axis.
abstract: HT1080 - a human fibrosarcoma-derived cell line - forms aggressive angiogenic tumours in immuno-compromised mice. In spite of its extensive use as a model of tumour angiogenesis, the molecular event(s) initiating the angiogenic program in these cells are not known. Since hypoxia stimulates tumour angiogenesis, we examined the hypoxia-induced events evoked in these cells. In contrast to cells grown under normoxic conditions, hypoxia-primed (1% O(2)) HT1080 cells formed robust tubules on growth factor-reduced matrigel and formed significantly larger tumours in xenograft models in a chetomin-sensitive manner, indicating the role of HIF-1α-mediated transcription in these processes. Immuno-histochemical analyses of tumours formed by GFP-expressing HT1080 cells clearly showed that the tumour cells themselves expressed various angiogenic markers including Neuropilin-1 (NRP-1) and formed functional vessels containing red blood cells, thereby unambiguously demonstrating the vasculogenic mimicry of HT1080 cells in vivo. Experiments performed with the HT1080 cells stably transfected with plasmid constructs expressing shNRP-1 or full-length NRP-1 clearly established that the HIF1α-mediated up-regulation of NRP-1 played a deterministic role in the process. Hypoxia-exposure resulted in an up-regulation of c-Myc and OCT3/4 and a down-regulation of KLF4 mRNAs, suggesting their involvement in the tumour formation and angiogenesis. However, silencing of NRP-1 alone, though not affecting proliferation in culture, was sufficient to abrogate the tumour formation completely; clearly establishing that the hypoxia-mediated HIF-1α-dependent up-regulation of NRP-1 is a critical molecular event involved in the vasculogenic mimicry and tumor formation by HT1080 cells in vivo.
authors.affiliation: Stem Cell Lab, National Centre for Cell Science, National Centre for Cell Science Complex, University of Pune Campus, Ganeshkhind, Pune, Maharashtra, India.
authors.forename: Roli M
authors.initials: RM
authors.lastname: Misra
authors.forename: Manmohan S
authors.initials: MS
authors.lastname: Bajaj
authors.forename: Vaijayanti P
authors.initials: VP
authors.lastname: Kale
mesh_terms: D000818:Animals; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D004220:Disulfides / Q000494:pharmacology; D005354:Fibrosarcoma / Q000098:blood supply* / Q000235:genetics / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D020868:Gene Silencing; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D026121:Indole Alkaloids / Q000494:pharmacology; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018218:Neoplasms, Fibrous Tissue / Q000098:blood supply* / Q000235:genetics / Q000378:metabolism; D009389:Neovascularization, Pathologic; D039942:Neuropilin-1 / Q000235:genetics* / Q000378:metabolism; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology*; D010957:Plasmids; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
chemical_list: D004220:Disulfides; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D026121:Indole Alkaloids; C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; C489428:Myc protein, mouse; D050814:Octamer Transcription Factor-3; C494174:Pou5f1 protein, mouse; D016271:Proto-Oncogene Proteins c-myc; C001598:chetomin; D039942:Neuropilin-1; D010100:Oxygen