Role of Vasodilator Stimulated Phosphoprotein (VASP) in Pathogenesis of Osteosarcoma and its Association with Alkaline Phosphatase Levels

Osteosarcoma is the most common bone tumour seen in the paediatric and adolescent age group. Most osteosarcomas are highly malignant tumours arising within the bone. Several markers for diagnosis and prognosis have been proposed in osteosarcoma namely, vascular endothelial growth factor (VEGF), bone alkaline phosphatase, osteocalcin. A new family of a protein known as Vasodilator-stimulated phosphoprotein, which is known to promote cell migration may also have a role in metastasis of osteosarcoma. So this study was planned to estimate the serum concentration of VASP in patients of osteosarcoma and to find the correlation of it with serum alkaline phosphatase and compare them with controls. Fifty patients attending the Orthopaedics clinics were selected for the study and were divided into two groups. Histopathologically confirmed cases of osteosarcoma (localized without metastasis) were included in Group I and age and sex matched twenty five patients with musculoskeletal pain in Group II as controls. Serum alkaline phosphatase levels and serum vasodilator-stimulated phosphoprotein (VASP) levels were estimated and the result was analysed using standard statistical methods. It has been found that serum VASP levels were significantly decreased and serum alkaline phosphatase levels were significantly raised in patients with osteosarcoma (Group I) as compared to the controls. Serum alkaline phosphatase levels showed a positive correlation with serum VASP levels in control, which got inverted in osteosarcoma cases. VASP, a member of ENA/VASP family, has been implicated in regulating key cellular functions (namely shape change, adhesion and migration) due to its ability to modify dynamic cytoskeleton. The negative correlation between VASP and ALP in osteosarcoma patients also supported the role of VASP in bone mineralization and tumorigenesis. So, VASP in osteosarcomas may lead to improved stratification of outcome and development of novel therapeutic modalities.