Screening of human fetal brain cDNA library by glioblastoma (GB) and normal human brain total cDNA probes revealed 80 differentially hybridized clones. Hybridization of the DNA from selected clones and the same cDNA probes confirmed this difference for 38 clones, of which eight clones contained Alu-repeat inserts with increased levels in GB. Thirty clones contained cDNAs corresponding to mitochondrial genes for ATP synthase subunit 6 (ATP6), cytochrome c oxidase subunit II (COXII), cytochrome c oxidase subunit III (COXIII), NADH dehydrogenase subunit 1 (ND1), NADH dehydrogenase subunit 4 (ND4), and mitochondrial 12S rRNA. The levels of all these mitochondrial transcripts were decreased in glioblastomas as compared to tumor-adjacent histologically normal brain. Earlier we found the same for cytochrome c oxidase subunit I (COXI) Serial Analysis of Gene Expression (SAGE) showed lower content of the tags for all mitochondrial genes in GB SAGE libraries and together with our experimental data could serve as evidence of general inactivation of the mitochondrial genome in glioblastoma-the most malignant and abundant form of human brain tumor. q 2004 Published by Elsevier Ireland Ltd.

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.

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Aim. To characterize the immortalized 293 cell line after stable transfection with human oncogene (CHI3L1). Methods. 293 cells, stably transfected with pcDNA3.1_CHI3L1, and 293 cells, stably transfected with pcDNA3.1 as a negative control, were used throughout all experiments. The clones of CHI3L1-expressing 293 cells and 293 cells, transfected with pcDNA3.1, were analyzed by immunofluorescence and confocal microscopy. Cell proliferation was measured using MTT assay; analyses of ERK1/2 and AKT activation and their cellular localization were performed with anti-phospho-ERK and anti-phospho-AKT antibodies. Specific activation of MAP and PI3 kinases was measured by densitometric analysis of Western-blot signals. Results. The obtained results show quite modest ability of CHI3L1 to stimulate cell growth and reflect rather an improved cellular plating efficiency of the 293 cells stably transfected with pcDNA3.1_CHI3L1 as compared to the 293 cells transfected with an «empty» vector. ERK1/2 and AKT are activated in the 293_CHI3L1 cells. In these cells phosphorylated ERK1/2 were localized in both cell cytoplasm and nuclei while AKT only in cytoplasm. The 293_CHI3L1 cells differed from the 293 cells, transfected with an «empty» vector, in their size and ability to adhere to the culture plates. Conclusions. The overexpression of CHI3L1 is likely to have an important role in tumorigenesis via a mechanism which involves activation of PI3K and ERK1/2 pathways. The tumors which can be induced by orthotopic implantation of the transformed human cells with overexpressed human oncogene CHI3L1 into the rat brain can be used as a target for anticancer drug development