Vascular Channel Formation by Osteosarcoma Cells in Vitro: Vasculogenic Mimicry

Objective: To observe whether there is evidence for vascular channel formation by osteosarcoma cellsin vitro and to illustrate mechanism of vasculogenic mimicry in osteosarcoma.Methods: 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 under a phase contrast microscope and an electron microscope.Results: Observation under light microscopy and electron microscopy showed that high aggressive osteosarcoma cells line (U-2OS) formed networks containing channels when grown in three-dimensional culture containing type I collagen in the absence of endothelial cells or fibroblasts.Conclusion: 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. Key words osteosarcoma cells line - vasculogenesis mimicry - angiogenesis - 3-dimensional cultures This study was supported in part by the National Natural Sciences Foundation of China (No. 30271314).

The expression of TRAIL and its receptors in osteosarcoma cells and the apoptosis effect of a combination of TRAIL, adriamycin and IFN-γ on MG-63 cells

Objective： This study investigated the effects of rh-TRAIL with or without chemotherapeutic drugs on the apoptosis of the osteosarcoma cell line, MG-63, and the influence of chemotherapeutic drugs on changes in the expression of DR5 and YinYang 1 （YY1） in MG- 63 cells. Methods： The effects of treatment with rh-TRAIL alone and/or chemotherapetic drugs on MG-63 cell growth inhibition and apoptosis were measured using the MTT assay, FACS analysis ofAunexin V labeled cells, and the mRNA changes of DR5 and YY1 were detected by RT-PCR. Results： Rh-TRAIL protein inhibited the growth of MG-63 cells, and this inhibition was increased by adriamycin and IFN-γ. Adriamycin and IFN-γ significantly facilitated the induction of the expression of DR5 and reduced the expression of YY1. Conclusion： The apoptosis-inducing effect of rh-TRAIL in MG-63 cells was enhanced by chemotherapeutic drugs.

The experiment study on LMWH inhibiting the expression of Livin and inducing the apoptosis of osteosarcoma cells

Objective: To investigate the inhibitory effects of LMWH suppressing the expression of Livin and inducing the apoptosis of the osteosarcoma cells. Methods: Osteosarcoma cells line MG-63 was cultured in vitro. MTT assay and flow cytometry were used to study the effect of LMWH with different concentration suppressed the prolifetation and induced apop- tosis in osteosarcoma cells line MG-63. The expression of Livin of osteosarcoma cells line MG-63 was analysed by the im- munohistochemistrical method and PT-PCR. Results: Low molecular weight heparin could inhibit the growth of osteosarcoma cell line MG-63. With the LMWH's increasing, the apoptosis rate was increased significantly. Immunohistochemistrical method and PT-PCR showed that the expression of Livin of osteosarcoma cells line MG-63 declined obviously than that before medi- cation. Conclusion: LMWH has very strong anti-tumor effect in vitro. The possible mechanisms of LMWH anti-tumor effect are associate with the effect of suppressing the expression of Livin and inducing cell apoptosis.

Extraction, Purification and Identification of Bone Morphogenetic Protein in Conditioned Medium of Osteosarcoma Cell (MG-63)

Objective: To find out a method of extraction and purification of bone morphogenetic protein (BMP) from osteosarcoma cell conditioned medium, and evaluate the biological activity of BMP.Methods: Conditioned medium of osteosarcoma cell lines (MG-63) was collected, concentrated and dialyzed. The concentrated protein was purified through gel chromatography on Sephcryl-S-100. The purified protein was tested by BMP monoclonal antibody (McAb), its molecular weight (MW) was determined by SDS-PAGE and its biological activity was demonstrated by heterotopic ossification.Results: The purified protein was proved to be BMP by BMP McAb, had a satisfactory heterotopic ossification, and its MW was about 21 kD.Conclusion: BMP existed in the conditioned medium of osteosarcoma cell and had a satisfactory biological activity after purification. Because osteosarcoma cell can be cultured and grew for a long timein vitro, this method will be helpful to a vast extraction of BMP and clinical application. Key words osteosarcoma cell - conditioned medium - bone morphogenetic protein - protein purification This project was a key scientific and technological program of Hubei Provicial Scientific and Technological Committee (No. 002p1503).

Human Soluble TRAIL Protein Inducing Apoptosis in Osteosarcoma Cell

This study is to examine the effect of human recombinant soluble TRAIL （TNF-related apoptosis-inducing ligand） protein inducing apoptosis in MG-63 human osteosarcoma cells. The inhibitive rates of TRAIL to MG-63 cells were detected by MTT assay. The apoptosis induced by TRAIL in MG-63 human osteosarcoma cells was analyzed with FACS and TUNEL and the apoptotic bodies were observed by transmission electron microscope. MTT assay showed that the inhibitive rates of 500, 1 000, 2 000 and 4 000 ng/mL TRAIL for 24 h were 10.1%, 24.3%, 50.6% and 97.7% respectively. Flow cytometric analysis showed that after MG-63 cells were treated with 2 gg/mL TRAIL for 6 h, obvious apoptotic peak would immediately appear before diploid peak. Human soluble TRAIL protein can quickly kill MG-63 osteosarcoma cells selectively, and may have potential value for clinical treatment of osteosarcoma.

Effect of NS398 on inducing apoptosis and down-regulating Bcl-2 protein in human osteosarcoma cell MG-63 line

Objective： This study investigated the effect of NS398 on anti-proliferation and the mechanism of inducing apoptosis of human osteosarcoma cell MG-63 line in vitro. Methods： Growth suppression was detected by MTT method. Special morphological changes of apoptosis were observed by transmission electron microscopy （TEM） and DNA fragments electrophoresis. The apoptotic rates were quantified by flow cytometry （FCM）. And Bcl-2 protein level were detected by Western Blotting assay. Results： Different concentration NS398 inhibited the cell growth. Through TEM and DNA electrophoresis, the special morphological changes were observed after 24, 48 and 72 h treatment with NS398. The apoptotic rates of MG-63 cells treated with NS398 were respectively, significantly higher than that of the control group（ P 〈0.01 ）. Western blot assay showed that NS398 reduced Bcl-2 protein expression. Conclusion： NS398 suppressed the proliferation of human osteosarcoma cell MG-63 line and induced apoptosis. The mechanism may be associated with down-regulation expression level of bcl-2 protein.

Biological behaviors of two novel syngeneic human osteosarcoma cell lines

Objective To characterize and compare the different biological behaviors of two novel human osteosarcoma cell lines,Zos and Zos-M,established respectively from the primary site and the skip metastasis of an osteosarcoma patient.Methods Two

Artesunate inhibits growth and induces apoptosis in human osteosarcoma HOS cell line in vitro and in vivo

This paper aims to investigate the effects of artesunate (ART) on growth and apoptosis in human osteosarcoma HOS cell line in vitro and in vivo and to explore the possible underlying mechanisms.Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.The induction of apoptosis was detected by light and transmission electron microscopy and flow cytometry.Western blot analysis was used to investigate the related mechanisms.Nude mice were further employed to investigate the antitumour activity of ART in vivo.MTT assay results demonstrated that ART selectively inhibits the growth of HOS cells in a dose-and time-dependent manner.Based on the findings of light and transmission electron microscopy,Hoechst 33258 staining,and fluorescein isothiocyanate (FITC)-annexin V staining,the cytotoxicity of ART in HOS cells occurs through apoptosis.With ART treatment,cytosolic cytochrome c was increased,Bax expression was gradually upregulated,Bcl-2 expression was downregulated,and caspase-9 and caspase-3 were activated.Thus,the intrinsic apoptotic pathway may be involved in ART-induced apoptosis.Cell cycle analysis by flow cytometry indicated that ART may induce cell cycle arrest at G2 /M phase.In nude mice bearing HOS xenograft tumours,ART inhibited tumour growth and regulated the expressions of cleaved caspase-3 and survivin,in agreement with in vitro observations.ART has a selective antitumour activity against human osteosarcoma HOS cells,which may be related to its effects on induction of apoptosis via the intrinsic pathway.The results suggest that ART is a promising candidate for the treatment of osteosarcoma.