Expression of the neural RNA-binding protein musashi1 in human gliomas

Tumor cells arising from a particular tissue may exhibit the same gene expression patterns as their precursor cells. To test this proposition, we have analyzed the expression of a neural RNA-binding protein, Musashil, in primary human central nervous system (CNS) tumors. In rodents, Musashil is expressed predominantly in proliferating multipotent neural precursor cells, but not in newly generated postmitotic neurons. The expression of Musashil is downregulated with the successive progression of neurogenesis. In normal adult human tissues, we detected low levels of Musashil expression in brain and testis by RT-PCR analysis. In an RNA panel of 32 cancer tissues and cell lines, elevated expression of Musashil was seen in all five malignant gliomas studied, in contrast to the slight expression seen in other tumor cells, including those in several melanomas and a prostate cancer. Western blot analysis showed strong Musashil expression in malignant gliomas compared with nonneoplastic brain tissue. Glioblastomas, the most malignant form of glioma, showed higher Musashil expression than less malignant gliomas by immunohistochemical analysis. Tumors with strong Musashil expression tended to have high proliferative activity. Thus, the expression of Musashil correlated with the grade of the malignancy and proliferative activity in gliomas. These results suggest that primary CNS tumors may share gene expression patterns with primitive, undifferentiated CNS cells and that Musashil may be a useful marker for the diagnosis of CNS tumors. (C) 2001 Wiley-Liss, Inc.