Aim. In osteosarcoma, local control of the tumour is absolutely critical otherwise the chances of long term survival are <10% and may effectively approach zero. Radiotherapy is used in case of non-resectable tumours. Histone deacetylase inhibitors (HDACIs) can enhance the sensitivity of cells to photon radiation (XRT) by altering numerous molecular pathways. Therefore, we investigated the effect of the pan-HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) on radiation response in osteosarcoma (OS) and rhabdomyosarcoma (RMS) cell lines. Methods. Clonogenic survival, cell cycle analysis, apoptosis and gammaH2AX phosphorylation as a marker of DNA double strand breaks (DSBs) were examined in two OS (KHOS-24OS, SAOS2) and two RMS (A-204, RD) cell lines treated with SAHA alone and SAHA plus XRT, respectively. Protein expression was investigated via immunoblot analysis, cell cycle analysis, measurement of apoptosis and gammaH2AX expression were performed using flow cytometry. Results. In the sarcoma cell lines, SAHA induced an inhibition of cell proliferation and clonogenic survival and lead to a significant radiosensitization. Furthermore, SAHA significantly increased radiation-induced apoptosis in the OS cell lines, whereas in the RMS cell lines radiation-induced apoptosis was insignificant with and without SAHA. In both tumour entities, gammaH2AX expression was significantly increased when XRT was combined with SAHA treatment which was correlated with attenuation of radiation-induced DNA repair protein expression. Conclusion. Our results show that HDACIs enhance radiation action in OS and RMS cell lines. Inhibition of DNA repair rather than increased apoptosis induction after exposure to HDACIs could be one key mechanism of radiosensitization by HDACIs

SSX was initially identified as a melanoma associated tumour antigen MEL2 and in the SS18/SSX fusion gene of synovial sarcoma. It consists of a family of nine, highly homologous X chromosome genes, being SSX1, SSX2 and SSX4 the most commonly expressed in tumours. In normal tissue, SSX expression is restricted to germ cells, trophoblasts, and mesenchymal stem cells. In malignant cells, SSX expression is over-represented in sarcomas. SSX expression is epigenetically regulated by methylation and histone deacetylation. Aim. To investigate the oncogenic properties of SSX. Validate it as tumour target and identify lead compounds. Methods. RNAi system for conditional silencing of SSX expression, Protein analysis and Mass Spec, PCR arrays, tumour xenographs and drug library screening. Results. SSX expression peaks at the G1/S phase of the cell cycle where it interacts with histone H3, H4 and β-catenin. This interaction promotes the phosphorylation of β-catenin at tyrosine residues and the transactivation of β-catenin genes MMP2 and cyclin D1. The association of SSX and MMP2 expression resulted in an increased invasion capacity of tumour cells. In vivo, silencing of SSX in tumour xenographs significantly affected the tumour growth. These tumours were characterized by large necrotic areas, impaired vascularization and cytoplasmic β-catenin. In contrast, tumour xenographs expressing SSX were highly proliferative, vascularized and exibited nuclear β-catenin. We further screened a chemical library and have identified lead compounds that target SSX. Conclusion. Our results demonstrate that SSX is a tumour target for drug development. We hypothesise that drugs targeting of SSX could affect functions related with the mesenchymal cell phenotype having potential cytostatic effect in sarcomas and/or epithelial tumour cells that undergo a epithelial-to-mesenchymal transition prior to metastasis

Aims

Bone metastasis ultimately occurs due to a complex multistep process, during which the interactions between cancer cells and bone microenvironment play important roles. Prior to colonization of the bone, cancer cells must succeed through a series of steps that will allow them to gain migratory and invasive properties; epithelial-to-mesenchymal transition (EMT) is known to be integral here. The aim of this study was to determine the effects of G protein subunit alpha Q (GNAQ) on the mechanisms underlying bone metastasis through EMT pathway.

Aims

Tocilizumab, an interleukin-6 (IL-6) receptor (IL-6R) targeting antibody, enhances the anti-tumour effect of conventional chemotherapy in preclinical models of cancer. We investigated the anti-tumour effect of tocilizumab in osteosarcoma (OS) cell lines.

Objectives

Eukaryotic translation initiation factor 3 (eIF3) is a multi-subunit complex that plays a critical role in translation initiation. Expression levels of eIF3 subunits are elevated or decreased in various cancers, suggesting a role for eIF3 in tumorigenesis. Recent studies have shown that the expression of the eIF3b subunit is elevated in bladder and prostate cancer, and eIF3b silencing inhibited glioblastoma growth and induced cellular apoptosis. In this study, we investigated the role of eIF3b in the survival of osteosarcoma cells.

We investigated the use of hypoxia-inducible factor (HIF) proteins as prognostic markers in chondrosarcoma and the relationship of HIF to the biological characteristics of cartilage tumours. The expression of HIF-1α, HIF-2α, proliferating cell nuclear antigen (PCNA) and microvessel density (MVD) were measured immunohistochemically in 29 specimens of cartilage tumour.

There was no HIF-1α and HIF-2α staining in any of the nine benign cartilage tumours. In 20 specimens of chondrosarcoma, the rate of HIF-1α and HIF-2α expression was 40% and 25%, respectively. The tumour size (≥ 8 cm), histological grade (grade 2 and grade 3) surgical margin (marginal and intralesional) and HIF-1α expression (positive) correlated significantly with a shorter disease-free survival. There was a significant association between HIF-1α and the MVD and a strong trend towards a correlation between HIF-1α and the PCNA index or histological grade.

Our findings suggest that HIF-1α protein may be a useful objective marker in the assessment of the prognosis in chondrosarcoma, since it plays an important role in tumour angiogenesis and cell proliferation.