IDENTIFICATION AND CHARACTERIZATION OF HUMAN BETA-2-CHIMAERIN - ASSOCIATION WITH MALIGNANT TRANSFORMATION IN ASTROCYTOMA

Molecular processes resulting in the malignant transformation from low - to high-grade astrocytoma remain poorly understood, Using reverse tr anscriptase PCR, we identified a gene that is differentially expressed in normal brain and low-grade astrocytoma compared to glioblastoma ti ssues. This gene is identical to human beta 2-chimaerin, which encodes a 468-amino acid GTPase-activating protein for p21rac. The gene was l ocalized to human chromosome 7p15.3 by fluorescence in situ hybridizat ion mapping, Human beta 2-chimaerin is expressed in a variety of human tissues, with the highest expression level detected in human brain an d pancreas. RNase protection assays indicated that the expression leve l of this gene is high in all the normal brain and low-grade astrocyto ma samples tested compared to malignant gliomas. The down-regulation o f beta 2-chimaerin expression in the high-grade gliomas suggests that decreased expression of this gene may be a feature of progression in t he development of malignant glioma.