Overexpression of YKL-39 Gene in Glial Brain Tumors

More than forty genes with considerably increased expression in glioblastoma as compared to normal human brain were identified by SAGE. One of the most prominent among them was CHI3L2 (YKL-39) gene, which encodes 39 kDa chitinase-like protein. Northern blot hybridization confirmed the data of SAGE for the majority of glioblastomas. Anaplastic astrocytomas could be divided on two groups: in one of them the YKL-39 expression was completely undetectable, but in the other group quite high contents of YKL-39 mRNA were detected. In this study, preliminary data show that patients with undetectable expression of YKL-39 in anaplastic astrocytomas did not have recurrent tumors quite long (more than 2-3 years) period of time. YKL-39 RNA has not been detected in diffuse astrocytomas and in all (but one) samples of normal brain. Increased expression of YKL-39 gene in glioblastomas was shown also at the protein level. Western blots did not shown simultaneous production of YKL-39 and YKL-40, in spite of having high degree of their sequence identity. Increased expression of YKL-39 in subsets of patients with glial tumors, reported here for the first time, together with abnormal increase of the YKL-40 gene expression may be a novel molecular marker for glial tumors.