Chondrosarcoma responds poorly to adjuvant therapy and therefore, new targeted therapy is required. Animal models have been utilised to test therapeutic candidates, however clinically relevant, orthotopic models are lacking. The aim of this study was to develop such a model.

In vitro: two human chondrosarcoma cell lines, JJ012 and FS090, were compared with respect to proliferation, colony formation, invasion, MMP-2 and MMP-9 secretion, osteoclastogenesis, endothelial tube stimulation, and expression of the angiogenic factor VEGF, and the anti-angiogenic factor RECK on western blotting. In vivo: 20,000 cells (JJ012 or FS090) were injected either into the intramedullary canal of the mouse tibia (n=5 for each cell line), or into the tibial periosteum (n=5 for each cell line). Animals were measured, and x-rayed weekly. Once euthanised, tibias and lungs were preserved, embedded and sectioned to determine the presence of tumour and lung metastases.

In vitro: compared with FS090, JJ012 demonstrated significantly higher proliferative capacity at both day two and day four (p=0.017, and p=0.01). JJ012 had a significantly greater ability to invade Matrigel with an average number of 812.5 invading cells, versus 140.8 FS090 cells (p=0.0005). JJ012 readily formed colonies in collagen I, while FS090 formed none. JJ012 conditioned medium stimulated endothelial tube formation and osteoclastogenesis with a greater potency than FS090 conditioned medium. In vivo: tumours formed in the intratibial and periosteal groups injected with JJ012, whilst no mice injected with FS090 cells developed discernable tumours on physical inspection, caliper measurement or histological section. Periosteal tumours grew to three times the non-injected limb size by seven weeks, whereas intratibial injected limbs required 10 weeks to achieve the same extent of tumour growth. All JJ012 periosteal tumours resulted in lung micrometastases, while only 2/4 JJ012 intratibial tumours demonstrated metastases. Lung metastases stained positive with Von Kossa and alizarin red stains, indicating a tendency for calcification, which is similar to metastases in the human disease. Sectioned tumour tissue demonstrated features of grade II-III chondrosarcoma. Similarities with the human disease were also noted on the X-ray, including endosteal scalloping, and cortical thickening.

Both intratibial and periosteal JJ012 models replicate the site, morphology, and many behavioural characteristics of human chondrosarcoma. Local tumour invasion of bone and spontaneous lung metastasis offer valuable assessment tools to test the potential of novel agents for future chondrosarcoma therapy.

Aims: RECK protein is involved in angiogenesis and matrix-metalloproteinase interaction. In common cancers RECK may exert tumour control, while in sarcomas, there is insufficient research to confirm this. Our study aims to investigate the role of RECK in osteo-sarcoma (OS) and chondrosarcoma (CS) angiogenesis, using clinical data and an in vitro angiogenesis assay.

Methods: Seven OS biopsy samples, 11 OS metastases and 24 samples of CS were stained for the RECK protein using immunohistochemistry. RECK expression in vessels supplying sarcoma tissue was semi-quantified using ImageProPlus software to determine staining density. RECK density in tumour vessels was compared with density in vessels of 18 normal tissues. The human endothelial cell line, HMEC-1, was cultured and then transfected with a plasmid containing the RECK gene. HMEC-1 cells over-expressing RECK were then distributed into wells containing 100% Matrigel. Formation of vessel-like structures was observed and photographed at 8 hours. Comparison was made with a non-transfected HMEC-1 group, and an empty vector transfected HMEC-1 group. Results: RECK is predominantly expressed in vessels supplying both sarcomas and less frequently in the tumour cells. RECK density in OS and CS primary tumour vessels was no different to normal vessels (p> 0.05). However there was a significantly higher RECK density in the vessels of OS metastasis tissue (0.76 ODU-optical density units), compared with primary OS vessels (0.57 ODU, p< 0.05), and normal vessels (0.56 ODU, p< 0.05).

The average number of tube formations in the RECK transfected HMEC-1 cells was 67.8, compared with 42 in the empty vector group (p=0.03) and 54.1 in the control group (p=0.03). The average maximal wall thickness of tube formations was 100.7um versus 77.4um in the empty vector group (p=0.04) and 83.0um in the control group (p=0.09).

Conclusions: RECK is upregulated in vessels supplying OS metastases compared to vessels in primary sarcoma and normal tissue, suggesting an active role in angiogenesis. Replication of these conditions in vitro using the HMEC-1 tube formation assay demonstrates the ability of RECK to increase vessel formation within a matrix while maintaining vessel wall thickness. In sarcoma RECK may have pro-angiogenic properties and could be an important part of the metastatic cascade.

The human RECK protein is often downregulated in cancer, which is thought to contribute to tumour progression. The role of RECK is not yet characterised in bone sarcomas. This study aims to determine the effects of increased human RECK protein expression in osteo-sarcoma and chondrosarcoma using cell invasion assays and tumour size on MRI.

The human osteosarcoma and chondrosarcoma cell lines (SaOS-2 and OUMS27 respectively) were cultured then transfected with either a plasmid containing the RECK gene, an empty vector, or not at all (control). Cells were incubated at 37 degrees within invasion chambers containing 75% matrigel. Cells invading the matrigel were counted after 3 days. Fifteen chondrosar-coma samples were stained using immunohistochemistry for the human RECK protein. RECK expression was determined to be positive or negative. MRI scans corresponding to tumour samples were viewed and the maximal tumour diameter out of all planes was manually determined with computer imaging software.

The SaOS-2 invasion assay demonstrated increased cell invasion in the RECK transfected group with an average of 502.3 invading cells, compared with 129.0 for the empty vector group (p=0.004) and 100.6 for the control group (p=0.001).

The OUMS-27 invasion assay also demonstrated increased cell invasion in RECK transfected cells with an average of 86.3 invading cells compared with 22.8 in the empty vector group (p=0.067) and 67.8 in the control group (p=0.17).

For MRI data, there were two distinct groups with roughly equal distributions of tumour grades. Group 1 had maximal tumour diameters of less than 70 mm, compared to group 2, being greater than 70mm (p=0.0006). In group 1 only 1/8 demonstrated RECK expression, while in group 2, 5/7 were RECK positive (p=0.041 Fisher exact test).

RECK overexpression in osteosarcoma and chondro-sarcoma cell lines appears to increase invasive capacity, and stands in contrast to RECK data in carcinomas. Furthermore, RECK expression in patient chondrosar-coma samples is associated with larger tumours. RECK may therefore function differently in sarcoma.

Pigment epithelium-derived factor (PEDF) is the most potent endogenous inhibitor of angiogenesis and decreased PEDF expression has been shown, in many tumours, to be associated with increased intratumoural microvascularity, enhanced tumour growth and metastases and poor patient prognosis. We evaluated the role of PEDF in osteosarcoma growth inhibition and examined it’s potential as a possible anti-cancer therapeutic agent.

We investigated the effects of overexpressed and recombinant PEDF (rPEDF) in several cell-based assays and in two orthotopic models of osteosarcoma (UMR 106-01 and SaOS-2).

In vitro, overexpression of PEDF significantly decreased cell proliferation, migration, invasion and increased adhesion to collagen-1. rPEDF resulted in a dose-dependent inhibition of cell proliferation, increased collagen adhesion, decreased invasion, and down-regulation of VEGF. The pro-differentiation ability of rPEDF was confirmed by upregulation of several osteoblastic markers after treatment of a pre-osteoblastic cell line (UMR 201). Furthermore, both cell lines displayed increased mineralised nodule formation after administration. In vivo, PEDF inhibited osteosarcoma growth and metastasis when overexpressed and in the recombinant form. In addition, anti-tumour activity was observed upon testing with shorter peptides of PEDF. Pharmacoevaluation of rPEDF demonstrated stability within media over several days, and no significant side effects in terms of wound healing.

From these results, PEDF demonstrates multi-modal anti-tumour activity via anti-proliferation, anti-angiogenesis, pro-differentiation and anti-metastasis. PEDF may be a promising therapeutic agent for the treatment of patients with osteosarcoma.