Biopolymers and cell. 2005; 21 (2): 157 - 164

Activation of the expression of SPARC gene occuring early in astrocytic glioma progression

V. V. Dmitrenko, K. O. Shostak, O. I. Boyko, O. E. Simirenko, I. S. Gundorov, O. V. Khomenko, V. D. Rozumenko, T. A. Malisheva, M. I. Shamaev, Yu. A. Zozulya, V. M. Kavsan

Comparison of gene expression levels in astrocytic gliomas and human normal brain by SAGE revealed SPARC gene among those the expression of which increases most significantly (more than 5-fold, p 0.05). High level of the SPARC gene expression was detected in differentiated astrocytomas as well as in malignant glial tumors. Northern hybridization confirmed the SAGE results and showed that the SPARC gene expression elevated in astrocytomas of grade II-IV as compared to human normal brain. Two SPARC transcripts of about 2 and 3 kb length were detected almost in all the tumour samples. A longer mRNA is synthesized preferentially in tumour cells. The SPARC gene expression changes may play a role in the gliomas invasion and their angiogenesis. SPARC gene seems to be a specific invasion factor in view of our results on substantial enhancement of its expression in the gliomas of different malignancy grades and the corresponding literature data. Since the SPARC expression level is much higher in the tumours of low grades (differentiated astrocytomas) than that in the tumours of high grade (glioblastomas) this gene can not be regarded as a specific marker of increasing tumor aggressiveness.

Key words: astrocytomas, gliomas, SPARC gene, SAGE, genes expression.