CELL-ADHESION MOLECULE NR-CAM IS OVER-EXPRESSED IN HUMAN BRAIN-TUMORS

Using the technique of differential display-polymerase chain reaction (DD-PCR), we isolated a cDNA fragment that is over-expressed in gliobl astoma multiforme tissue as compared to normal brain tissue. Sequence analysis indicated that this sequence is identical to the previously i solated human neuron-glia-related cell adhesion molecule hNr-CAM. Gene -specific RT-PCR analysis indicated that hNr-CAM is over-expressed in high-grade astrocytomas, gliomas and glioblastoma tumor tissues as com pared to normal brain tissue. High levels of hNr-CAM expression also w ere observed in cell lines derived from astrocytomas, gliomas and glio blastoma multiforme tumors. Low levels of hNr-CAM expression were obse rved in neuroblastoma, meningiomas, melanoma, normal breast and prosta te tumor tissues. Northern blot analysis showed an alternatively splic ed mRNA of 1.4 kb in several tumors as compared to the 7.5 kb transcri pt found in normal brain tissue. Genomic Southern blot analysis of DNA from 3 brain tumor cell lines showed that over-expression of hNr-CAM in brain tumors was not due to gene amplification. In situ hybridizati on analysis indicated that 11 of the 20 human brain tumor samples stud ied showed hNr-CAM over-expression. Our results suggest that hNr-CAM i s over-expressed in malignant brain tumors and can serve as a novel ma rker for brain tumor detection and perhaps therapy. (C) 1998 Wiley-Lis s, Inc.