EXPRESSION OF ALPHA-B-CRYSTALLIN IN HUMAN BRAIN-TUMORS

We have previously shown that alphaB-crystallin is a heat-shock protei n which specifically accumulates in response to the expression of c-Ha -ras and v-mos oncogenes in mouse NIH 3T3 fibroblasts. Elevated levels of alphaB-crystallin mRNA or protein were shown to be associated with pathological conditions of the brain. Therefore, we have examined the expression of alphaB-crystallin in normal human brains and brain tumo rs by Western blot analysis. AlphaB-crystallin is moderately expressed in adult but not fetal brain. Elevated levels of alphaB-crystallin ex pression are observed in glial tumors such as astrocytoma, glioblastom a multiforme, and oligodendroglioma. AlphaB-crystallin in these tumors is predominately unphosphorylated. High amounts of accumulated alphaB -crystallin in astrocytic tumors are preferentially found in the more aggressive stages. Glioblastoma multiforme is exceptional in that high alphaB-crystallin expression is observed in only one half of the anal yzed samples whereas no alphaB-crystallin could be detected in the oth er. These results indicate that alphaB-crystallin may be a useful bioc hemical marker for studying the pathogenesis of various human brain tu mors. (C) 1993 Wiley-Liss, Inc.