Polysialic acid overexpression in malignant astrocytomas

Polysialic acid (PSA) is a carbohydrate binding on the neural cell adhesion molecule NCAM and impedes cell-cell interactions. It prevents neural progenitor cell differentiation and promotes their migration. Highly malignant tumours like small cell lung carcinoma (SCLC) also overexpress PSA and this correlates with a negative prognosis. Intra-operatively collected biopsies from 30 patients with different astrocytoma grades were immuno-histochemically examined to identify expression of PSA. Astrocytoma grade I and II had 4% PSA expressing cells whereas in grade III and IV the number of PSA expressing cells was 45%. This difference was statistically highly significant. In this short communication we show that highly malignant astrocytomas express significantly more PSA compared to less malignant astrocytomas. Cleavage of PSA could be used in future therapeutic approaches.