In contrast to EGFr gene overexpression, H-ras gene expression decreases in human gliomas

We have examined the expression of the epidermal growth factor receptor (EGFr) gene and 14 other oncogenes in several human gliomas. EGFr overexpression was apparent in 17 of 18 tumors. Nevertheless, remarkable amounts of aberrantly-sized EGFr mRNAs were not found in the 11 tumors examined. Among the 14 other oncogene probes employed, only the H-ras probe revealed changes in the expression level. The expression of this oncogene was 2-3-fold reduced in 13 of 18 tumors. In neural tissue the H-ras gene expression can be correlated with cellular differentiation. A correlation between H-ras protein expression and a favourable clinical prognosis was found in neuroblastomas. The decreased amounts of H-ras transcripts in gliomas may be a sign of a lower state of differentiation of the cells.