[Preliminary interpretation on the relationship between the phenotype of CD133+ cells and niche in transplanted human glioma in mice].

OBJECTIVE: CD133(+) tumor cells are regarded as cancer stem cells (CSCs), responsible for tumor initiation, development, and relevant with chemo- and radio-resistance of tumors. However, how the destiny of CD133(+) cells is regulated by their niche remains largely unknown. In this study the interpretation of the relationship between CD133(+) cells and their niche were performed through investigating the distribution characteristics of CD133(+) cells in transplanted human glioma xenograft. METHODS: CD133(+) tumor cell spheres or tumor cells transfected with red fluorescent protein (RFP) gene were implanted in situ, subcutaneously or intraperitonealy in nude mice, then the xenografts were dissected and embedded in paraffin, stained with hematoxylin-eosin (HE), tumor tissues were further stained against CD133 with immunohistochemical and immunofluorescent techniques. The pathological structures of tumors and distribution characteristics of CD133(+) tumor cells were observed under microscope and confocal fluorescence microscope. RESULTS: Under microscope, distribution of CD133(+) glioma cells showed certain regularity and can be classified morphologically into three types: cell clusters, in pairs and single cells. Distribution of CD133(+) cells can also be classified according to their distribution location: accumulating around tumor vasculature areas, among the vascular endothelial cells, or in the normal brain tissue and ventricles. Under fluorescence microscope and laser confocal microscope, some of vascular endothelial cells inside the tumor region and some cells around tumor vessels co-express CD133 and RFP. CONCLUSION: CD133(+) tumor cell clusters in nude mice are actually similar to those in CSCs spheres cultured in vitro. The single CD133(+) cells and CD133(+) cells in pairs represent asymmetric and symmetric division of CSCs within the CSCs niche, respectively. CD133(+) cells residing along tumor vessels are CSCs depending on CSC niche, and those locating far away from tumor blood vessels or tumor tissues, residing in normal brain tissues are the disseminated CSCs or neural stem cells which are not controlled or regulated by CSCs niche.

Alteration of DNA damage signaling pathway profile in radiation-treated glioblastoma stem-like cells.

The present study aimed to investigate the alteration of the DNA damage signaling pathway profile in radiation-treated glioblastoma stem-like cells (GSLCs), and also aimed to explore potential targets for overcoming glioblastoma radioresistance. Serum-free medium was used to isolate and culture GSLCs. Cell growth was detected using a cell counting kit-8 assay and cell sorting analysis was performed by flow cytometry. X-ray irradiation was produced by a Siemens-Primus linear accelerator. Reverse transcription-quantitative polymerase chain reaction (qPCR)was performed to investigate target genes. SPSS 15.0 was used for all statistical analyses. Human glioblastoma U251 and U87 cells were cultured in serum-free medium supplemented with epidermal growth factor and fibroblast growth factor 2, which constitutes tumor sphere medium, and demonstrated sphere formation, with significantly increased the proportion of CD133+ and Nestin+ cells, which are referred to as GSLCs. The present data revealed that treatment with 10 Gy X-ray radiation alters the expression profile of DNA damage-associated genes in GSLCs. The expression levels of 12 genes demonstrated a ≥2-fold increase in the irradiated U87 GSLCs compared with the untreated U87 GSLCs. Three genes, consisting of XPA, RAD50 and PPP1R15A, were selected from the 12 genes by gene functional searching and qPCR confirmatory studies, as these genes were considered to be potential targets for overcoming radioresistance. The expression of XPA, RAD50 and PPP1R15A is significantly increased in U87 and U251 radiation resistant GSLCs, indicating three potential targets for overcoming the radioresistance of GSLCs.