Expression of αB‐crystallin in human brain tumors

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Abstract
We have previously shown that αB-crystallin is a heat-shock protein which specifically accumulates in response to the expression of c-Ha-ras and v-mos oncogenes in mouse NIH 3T3 fibroblasts. Elevated levels of αB-crystallin mRNA or protein were shown to be associated with pathological conditions of the brain. Therefore, we have examined the expression of αB-crystallin in normal human brains and brain tumors by Western blot analysis. αB-crystallin is moderately expressed in adult but not fetal brain. Elevated levels of αB-crystallin expression are observed in glial tumors such as astrocytoma, glioblastoma multiforme, and oligodendroglioma. αB-crystallin in these tumors is predominately unphosphorylated. High amounts of accumulated aB-crystallin in astrocytic tumors are preferentially found in the more aggressive stages. Glioblastoma multiforme is exceptional in that high αB-crystallin expression is observed in only one half of the analyzed samples whereas no aB-crystallin could be detected in the other. These results indicate that αB-crystallin may be a useful biochemical marker for studying the pathogenesis of various human brain tumors.