The survival aspects for osteosarcoma patients have remained stable for over 25 years; indicating the importance of developing new, novel, treatment strategies.
Background of the research:
Survival for osteosarcoma patients has remained stable for several decades; this clearly highlights the importance of developing new treatment strategies. The spread of cancer to other areas in the body (the process known as metastasis) is responsible for poor patients’ prognosis. This project aimed to target osteosarcoma metastasis, to provide a better long-term outlook for patients.
A protein attached to the cell surface of cancer cells named NG2 (Neuron-glial antigen 2, also known as chondroitin sulphate proteoglycan 4, CSPG4) has been reported to play several key biological roles in other cancers, such as melanoma, glioblastoma and soft tissue sarcomas. Preliminary work by Professor Salter determined that this protein is also present in osteosarcoma cells and patient tumour samples. As NG2/CSPG4 is known to be associated with tumour growth, progression, spread and resistance to chemo and radio therapies in other tumour types, the study aimed to investigate if targeting this protein could result in a reduction in the spread and treatment resistance of osteosarcoma, therefore potentially improving patients’ survival.
Results of the study:
CSPG4 was confirmed to be expressed in a larger set of clinical samples, compared to healthy bone cells that are thought to give rise to osteosarcoma; supporting the idea that CSPG4 could act as a diagnostic tool or a therapeutic target in osteosarcoma.
In order to investigate whether CSPG4 alters osteosarcoma cell behaviour, cell lines were created which were CSPG4-positive and CSPG4-negative. CSPG4 however did not appear to influence the growth, invasion, or response to standard chemotherapy of osteosarcoma cells. Using a laboratory research model, CSPG4 also did not appear to influence tumour growth or spread.
Despite these overall disappointing results, the observation that CSPG4 is expressed at high levels on the surface of osteosarcoma cells continues to support the idea that the protein can be used as a biomarker, or used to guide immunotherapy drugs to the osteosarcoma cells.