Differentiation profile of brain tumor stem cells:a comparative study with neural stem cells

Understanding of the differentiation profile of brain tumor stem cells （BTSCs）, the key ones among tumor cell population, through comparison with neural stem cells （NSCs） would lend insight into the origin of glioma and ultimately yield new approaches to fight this intractable disease. Here, we cultured and purified BTSCs from surgical glioma specimens and NSCs from human fetal brain tissue, and further analyzed their cellular biological behaviors, especially their differentiation property. As expected, NSCs differentiated into mature neural phenotypes. In the same differentiation condition, however, BTSCs exhibited distinguished differences. Morphologically, cells grew flattened and attached for the first week, but gradually aggregated and reformed floating tumor sphere thereafter. During the corresponding period, the expression rate of undifferentiated cell marker CD 133 and nestin in BTSCs kept decreasing, but 1 week later, they regained ascending tendency. Interestingly, the differentiated cell markers GFAP and β-tubulinlII showed an expression change inverse to that of undifferentiated cell markers. Taken together, BTSCs were revealed to possess a capacity to resist differentiation, which actually represents the malignant behaviors of glioma.

Research on human glioma stem cells in China

Research on human glioma stem cells began early in the 21st century and since then has become a rapidly growing research field with the number of publications increasing year by year. The research conducted by our diverse group of investigators focused primarily on cell culture techniques, molecular regulation, signaling pathways, cancer treatment, the stem cell microenvironment and the cellular origin and function of glioma stem cells. In particular, we put forward our view that there are inverse or forward transformations among neural stem cells, glial cells and glioma stem cells in glioma tissues under certain conditions. Based on the background of the progress of international research on human glioma stem cells, we aim to share our progress and current findings of human glioma stem cell research in China with colleagues around the world.

Molecular Study on Differentiation-Associated Genes Involved in Both Malignant Progression of Glioma and Differentiation of Human Fetal Neural Stem Cells

OBJECTIVE It is unclear whether differentiation disturbances or deregulation of neural stem cells (NSCs) are the early key steps for gliomagenesis and tumor development. Furthermore, relevant molecular changes and gene-regulation pathways are unknown. This study focused on screening and validating differentiation-associated genes from both human NSCs and glioma cells with malignant progression, for the purpose of offering an experimental basis for the cellular origin of gilomas and molecular pathology of gliomagenesis. METHODS The differential-gene expression profiles of malignant progression of gliomas were established, then the differentiation related genes were screened out with a bioinformatics analysis. Expression levels of these genes was further analyzed in cultured human fetal NSCs undergoing differentiation processes with a semi-quantitative RT-PCR assay. RESULTS Eight genes were screened out from the gene-expression profiling of which the expression levels were associated with the differentiation processes of NSCs, namely CXCR4, TN-C, GLT1, IL1-RI, EGFR-8, CDC2, Ndr3 and MAPKK4. Three of them, ie., GLT1, CDC2 and MAPKK4, were further analyzed, showing that expression levels decreased with the differentiation processes of NSCs, and increased with the malignant progression of ganglioglioma. CONCLUSION Three differentiation associated genes were found negatively associated with NSCs differentiation and positively associated with malignant progression of gliomas, suggesting that differentiation disturbances of neural stem cells may be involved in oncogenesis, and that further studies on their roles in gliomagenesis should be conducted.

GENE EXPRESSION PROFILING OF GANGLIOGLIOMA MALIGNANT PROGRESSION BY cDNA ARRAY

Objective: To establish gene expression profiles associated with malignant progression of ganglioglioma. Methods: The primary and two recurrent glioma specimens were collected intraoperatively from the same patient who experienced tumor transformation into anaplastic astrocytoma and glioblastoma multiform for the first and second recurrence respectively. Gene expression was assayed through cDNA array and bioinformatics analysis. Results: A total of 197 differentially expressed genes with differential ratio value more than 3 compared with normal brain tissue were obtained. Among 109 functionally denned genes, those associated with development ranked the first by frequency, followed by genes associated with metabolism, differentiation, signal transduction and so on. As a result of cluster analysis among 368 genes, eleven genes were up regulated with malignant progression, while six genes were down regulated. Conclusion: Gene expression profiles associated with malignant progression of glioma were successfully established, which provides a powerful tool for research on molecular mechanisms of malignant progression of gliomas.