Effect of EPHA2-siRNA plasmid on biological behavior of human osteosarcoma cells in vitro / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the role of EPHA2 in regulating apoptosis, proliferation and vasculogenic mimicry of osteosarcoma cells, by gene silencing through RNA interference.</p><p><b>METHODS</b>EPHA2-siRNA plasmids were achieved by gene cloning. The plasmids were transfected into human osteosarcoma cells (MG63). The expression level of EPHA2 protein was measured by Western blotting. The proliferation, apoptosis and vasculogenic mimicry features of osteosarcoma MG63cells were assessed by light microscopy, MTIP assay, flow cytometry, annexin V-FITC/PI and HE staining, respectively.</p><p><b>RESULTS</b>The EPHA2-siRNA plasmid was confirmed by DNA sequencing. After treatment with Sequence-specific siRNA targeted EPHA2, the protein level of the transfected group decreased significantly. As compared to non-siRNA transfected cells, the transfected group showed lower proliferation, higher and earlier apoptosis and less osteosarcoma-generated vasculogenic mimicry.</p><p><b>CONCLUSION</b>EPHA2 gene may be involoved in apoptosis and proliferation of osteosarcoma cells, and may be necessary for vasculogenic mimicry. Down-regulation of EPHA2 expression by sequence-specific siRNA may be considered as a new option in the treatment of EPHA2 over-expressing cancer including osteosarcoma in future.</p>

Tumor blood vessels formation in osteosarcoma: vasculogenesis mimicry / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Osteosarcoma is characterized by high neovascularization and a high propensity for metastasis through bloodstream. This study was to examine whether there is evidence for vasculogenic mimicry in osteosarcoma and to illustrate mechanism of tumor blood vessels formation in osteosarcoma.</p><p><b>METHODS</b>Osteosarcoma cell lines (U-2OS) were tested for their ability to form tubular networks in three-dimensional culture containing type I collagen. The structures of the tubular networks were observed with phase contrast microscope and transmission electron microscope (TEM). Morphometric studies using hematoxylin and eosin (HE) stain and CD31 immunohistochemical stain to show tumor-lined channels in human osteosarcoma were also performed.</p><p><b>RESULTS</b>Observation with light microscope and TEM showed that highly aggressive osteosarcoma cell lines (U-2OS) formed networks containing channels when grown in three-dimensional culture containing type I collagen, in the absence of endothelial cells or fibroblasts. Morphometric observation using HE stain and CD31 immunohistochemical stain showed that tumor cell-lined channels were also detected in vivo in osteosarcoma; by comparison, all vascular areas in the pedicle of osteochondroma or outside osteochondroma were endothelial-lined.</p><p><b>CONCLUSION</b>These observations strongly suggest that aggressive osteosarcoma cells may generate vascular channels that facilitate tumor perfusion independent of tumor angiogenesis and have the ability of vasculogenic mimicry.</p>

Inhibitory effect of adenovirus mediated VEGF-siRNA on transplanted osteosarcoma in nude mice / 中国肿瘤生物治疗杂志

Objective: To investigate the inhibitory effect of adenovirus-mediated VEGF-siRNA on transplanted osteo- sarcoma in nude mice.Methods: VEGF-siRNA gene was cloned into the genome of replication-deficient adenovirus to construct Ad-VEGF-siRNA;the latter was then used to infect osteosarcoma MG63 cell line in vitro;and the expression of VEGF gene was detected by RT-PCR.Osteosarcoma transplantation model was established in nude mice;VEGF expression in tumor tissue was analyzed and the inhibitory effect on tumor growth and lung metastasis were also observed.Results: The recombinant adenovirus vector Ad-VEGF-siRNA was successfully constructed.In vivo and in vitro experiment both showed that Ad-VEGF-siRNA significantly downregulated VEGF expression in MG63 cells and transplanted tumor tissue. It was found that Ad-VEGF-siRNA significantly inhibited transplanted osteosarcoma growth(P