In an attempt to find a common DNA alteration occurring in human gliom
a, we examined DNA methylation in 34 gliomas of various pathological g
rades and compared them with those in normal cerebral subcortex DNA. T
he total methylated cytosine levels in the genome did not differ appre
ciably between the tumors and the normal tissues; however, the degree
of DNA methylation in several proto-oncogenes and suppressor oncogenes
showed some alterations. Among them, the c-fos gene demonstrated devi
ation from that of normal tissues in all cases examined, Suggesting th
at the alteration of c-fos gene methylation plays a role in the early
steps of human glioma development. (C) 1996 Wiley-Liss, Inc.