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.

[Metabolism of paeoniflorin by rat intestinal flora in vitro].

In order to clarify the effect of intestinal flora on the absorption and metabolism of paeoniflorin in vivo, the metabolism of paeoniflorin by rat intestinal flora was studied under the in vitro anaerobic condition. Paeoniflorin was incubated with rat anaerobic intestinal flora for 48 h, and UPLC was used to detect the changes of paeoniflorin at different incubation time points under the following chromatographic conditions：WelchromTM C18 chromatographic column (4.6 mm×100 mm, 5 µm), with 0.1% formic acid(A)-acetonitrile(B) as the mobile phase for gradient elution. The flow rate was 0.4 mL•min⁻¹, and column temperature was 30 ℃. UPLC-Q-TOF-MS with positive ion mode(ESI ion source) was applied to investigate the structural characterization of metabolic products. The structures of the metabolites were identified by accurate molecular weight, TOF-MS/MS fragmentation information, combined with retention time and literature data review, and the intestinal metabolic rules were then analyzed. After incubation for 24 h, the paeoniflorin was metabolized completely, and the resulting metabolites(albiflorin, albiflorinaglycone, deacylate albiflorin, deacylate albiflorin aglycone and paeonilactone-B) were detected in rat intestinal flora. The metabolic pathway analysis showed that the isolated rat intestinal flora first transformed peoniflorin into albiflorin, and then further metabolized by glucose removal, phenyl group removal, or four-membered ring pyrolysis and rearrangement. Paeoniflorin was gradually transformed into more hydrophobic metabolites with smaller molecular mass, which were better absorbed by the intestinal tract.

Rpb3 promotes hepatocellular carcinoma through its N-terminus.

The expression of RNA polymerase II subunit 3 (Rpb3) was found frequent up-regulation in Hepatocellular carcinoma (HCC) tumors. Significant associations could also be drawn between increased expressions of Rpb3 and advance HCC staging and shorter disease-free survival of patients. Overexpression of Rpb3 increased HCC cell proliferation, migratory rate and tumor growth in nude mice, whereas suppression of Rpb3 using shRNA inhibited these effects. For mechanism study, we found that Rpb3 bound directly to Snail, downregulated E-cadherin, induced HCC cells epithelial-mesenchymal transition (EMT). In particular, N-terminus of Rpb3 blocked Rpb3 binding to Snail, inhibited Rpb3-high-expression HCC cells proliferation, migration, tumor growth in nude mice, and also inhibited DEN-induced liver tumorigenesis. Furthermore, N-terminus of Rpb3 did not inhibit normal liver cells or Rpb3-low-expression HCC cells proliferation. These findings suggest that N-terminus of Rpb3 selectively inhibits Rpb3-high-expression HCC cells proliferation. N-terminus of Rpb3 may be useful in treating patients diagnosed with Rpb3-high-expression HCC.

Establishment of a green fluorescent protein tracing murine model focused on the functions of host components in necrosis repair and the niche of subcutaneously implanted glioma.

Due to progress in the research of glioma stem cells and the glioma niche, development of an animal model that facilitates the elucidation of the roles of the host tissue and cells is necessary. The aim of the present study was to develop a subcutaneous xenograft green fluorescent protein nude mouse model and use this model to analyze the roles of host cells in tumor necrosis repair. Tumors derived from the human glioma stem/progenitor cell line SU3 were subcutaneously implanted in green fluorescent protein nude mice. The implanted tumors were then passed from animal to animal for 10 generations. Finally, subcutaneous xenografts were assayed with traditional pathology, immunopathological techniques and fluorescence photography. For each generation, the tumorigenicity rate was 100%. Subcutaneous xenografts were rich in blood vessels, and necrotic and hemorrhagic foci, which highly expressed hypoxia-inducible factor-1α, tumor necrosis factor, Ki-67, CD68 and CD11b. In the interstitial tissue, particularly in old hemorrhagic foci, there were numerous cells expressing green fluorescent protein, CD68 and CD11b. Green fluorescent protein nude mouse subcutaneous xenografts not only consistently maintained the high invasiveness and tumorigenicity of glioma stem/progenitor cells, but also consisted of a high concentration of tumor blood vessels and necrotic and hemorrhagic foci. Subcutaneous xenografts also expressed high levels of tumor microenvironment-related proteins and host-derived tumor interstitial molecules. The model has significant potential for further research on tumor tissue remodeling and the tumor microenvironment.

[Host glial cell canceration induced by glioma stem cells in GFP/RFP dual fluorescence orthotopic glioma models in nude mice].

OBJECTIVE: During the process of tissue remodeling in human tumor transplantation models, the roles of the inoculated tumor cells and host tissue in tumor progression is still largely unknown. The aim of this study was to investigate the relationships and interactions between these two sides using GFP-RFP double fluorescence tracing technique. METHODS: Red fluorescence protein (RFP) gene was stably transfected into glioma stem cell line SU3, then SU3-RFP cells were transplanted into the brain of athymic nude mice with green fluorescence protein (GFP) expression. After the intracerebral tumors were formed, the relationship and interaction between GFP cells and RFP cells were analyzed. Highly proliferative GFP cells were screened out, and monocloned with micro-pipetting. DNA content assay, chromosome banding and carcinogenicity test of the GFP cells were performed to observe the GFP cells' cancerous phenotype in nude mice. RESULTS: In the transplantable tumor tissue, besides a great quantity of RFP cells, there were still a proportion of GFP cells and GFP/RFP fusion cells. The proportion of RFP cells, GFP cells and GFP/RFP cells were (88.99 ± 1.46)%, (5.59 ± 1.00)%, and (4.11 ± 1.020)%, respectively. Two monoclonal host GFP cells (H1 and H9) were cloned, which demonstrated the properties of immortality, loss of contact inhibition, and ultra-tetraploid when cultured in vitro. Both H1 and H9 cells expressed CNP, a specific marker of oligodendrocytes. The GFP cells also demonstrated 100% tumorigenic rate and high invasive properties in vivo. CONCLUSIONS: In this glioma transplantation model, the transplanted tumor tissues contained not only transplanted glioma stem cells but also cancerous host GFP cells. Our findings offer important clues to further research on the relationships among different members in the tumor microenvironment.

Incubation and application of transgenic green fluorescent nude mice in visualization studies on glioma tissue remodeling.

BACKGROUND: The primary reasons for local recurrence and therapeutic failure in the treatment of malignant gliomas are the invasion and interactions of tumor cells with surrounding normal brain cells. However, these tumor cells are hard to be visualized directly in histopathological preparations, or in experimental glioma models. Therefore, we developed an experimental human dual-color in vivo glioma model, which made tracking solitary invasive glioma cells possible, for the purpose of visualizing the interactions between red fluorescence labeled human glioma cells and host brain cells. This may offer references for further studying the roles of tumor microenvironment during glioma tissue remodeling. METHODS: Transgenic female C57BL/6 mice expressing enhanced green fluorescent protein (EGFP) were crossed with male Balb/c nude mice. Then sib mating was allowed to occur continuously in order to establish an inbred nude mice strain with 50% of their offspring that are EGFP positive. Human glioma cell lines U87-MG and SU3 were transfected with red fluorescent protein (RFP) gene, and a rat C6 glioma cell line was stained directly with CM-DiI, to establish three glioma cell lines emitting red fluorescence (SU3-RFP, U87-RFP, and C6-CM-DiI). Red fluorescence tumor cells were inoculated via intra-cerebral injection into caudate nucleus of the EGFP nude mice. Tumor-bearing mice were sacrificed when their clinical symptoms appeared, and the whole brain was harvested and snap frozen for further analysis. Confocal laser scanning microscopy was performed to monitor the mutual interactions between tumor cells and host brain cells. RESULTS: Almost all the essential tissues of the established EGFP athymic Balb/c nude mice, except hair and erythrocytes, fluoresced green under excitation using a blue light-emitting flashlight with a central peak of 470 nm, approximately 50% of the offsprings were nu/nu EGFP+. SU3-RFP, U87-RFP, and C6-CM-DiI almost 100% expressed red fluorescence under the fluorescence microscope. Under fluorescence microscopic view, RFP+ cells were observed growing wherever they arrived at, locating in the brain parenchyma, ventricles, and para-vascular region. The interactions between the transplanted tumor cells and host adjacent cells could be classified into three types: (1) interweaving; (2) mergence; and (3) fusion. Interweaving was observed in the early stage of tumor remodeling, in which both transplantable tumor cells and host cells were observed scattered in the tumor invading and spreading area without organic connections. Mergence was defined as mutual interactions between tumor cells and host stroma during tumorigenesis. Direct cell fusion between transplantable tumor cells and host cells could be observed occasionally. CONCLUSIONS: This study showed that self-established EGFP athymic nude mice offered the possibility of visualizing tumorigenesis of human xenograft tumor, and the dual-color xenograft glioma model was of considerable utility in studying the process of tumor remodeling. Based on this platform, mutual interactions between glioma cells and host tissues could be observed directly to further elucidate the development of tumor microenvironment.

[Effects of total intravenous anesthesia on evoked potentials during aneurysm clip placement surgery].

OBJECTIVE: To explore the influences of total intravenous anesthesia (TIVA) on the feasibility and success rate of monitoring the evoked potentials (EP) and examine the correlations between EP changes and clinical outcomes in intracranial aneurysm surgery. METHODS: Thirty-one patients undergoing intracranial aneurysm surgery received TIVA. TIVA was maintained with a target controlled infusion (TCI) of propofol and a continuous infusion of remifentanyl. The bilateral SEP (somatosensory evoked potential) and MEP (motor evoked potentials) were monitored intra-operatively. And the changes of evoked potential and success rate were recorded. The preoperative and postoperative neurological outcomes and radiological manifestations were compared. RESULTS: Bilateral SEP was detected in all cases. And the control side MEP was unsuccessfully monitored. Three patients had postoperative neurological deficits. The amplitudes of MEP and SEP declined simultaneously and failed to revert back to the baseline levels in 1 case. There was postoperative hemiplegia. And computed tomography showed multiple sites of ischemic brain infarction. CONCLUSION: The administration of TIVA with propofol and remifentanyl enables successful SEP and MEP monitoring during intracranial aneurysm surgery. This protocol may detect early cerebral ischemia and reduce the incidence of ischemic stroke.

[Preliminary studies on cell derivation of neovascularization in human glioma and its functional evaluation].

OBJECTIVE: The finding of vasculogenic mimicry (VM) in many solid tumors indicates that tumor cells themselves could participate in the construction of tumor vessels. However the origin of these cells is still not fully elucidated, and whether these vessels have the ability of blood-supply is still unclear. Preliminary studies were performed to investigate whether part of tumor neovascularity is derived from tumor stem cells (TSCs) and whether TSCs-derived vessels are functional. METHODS: Transplanted glioma tissues obtained from subcutaneous and orthotopic transplantation nude mouse models were processed into paraffin sections. In order to identify the cell origin and types of tumor vessels, sections were stained with CD31, CD34, CD133, GFAP, Ki67 and HLA, respectively. CD34-PAS staining was performed as well. A part of tumor-bearing mice were perfused with activated carbon through the systemic circulation and the distribution of activated carbon was observed. RESULTS: CD34-PAS staining showed that endothelium-dependent vessels (CD34(+), PAS(+)), VM vessels (CD34(-), PAS(+)), and the MVs (CD34(+), PAS(-)) could be seen in the transplantated tumors. Activated carbon particles were observed in all three types of vessels. CD31(+) cells adherent to the luminal surface of vessel wall. CD34(+) cells distributed along the vessels as well, but morphologically were more like a transition type between tumor cells and endothelial cells. Human specific Ki67 and HLA positive cells could be seen in the tumor vessels indicating that these vessels were derived from human tumor cells. Moreover, cells of tumor vessels were proved to be constructed by human tumor cells mainly and fusion cells of host cells and tumor cells under confocal microscope. CONCLUSIONS: Three types of blood supply sources including endothelium-dependent vessels, vasculogenic mimicry (VMs) and mosaic vessels (MVs) exist in transplantation tumors of human glioma. Glioma stem and progenitor cells (GSCPs) have the potential to differentiate and transdifferentiate into VMs and MVs.

Development of clinically relevant orthotopic xenograft mouse model of metastatic lung cancer and glioblastoma through surgical tumor tissues injection with trocar.

OBJECTIVE: Orthotopic models are important in cancer research. Here we developed orthotopic xenograft mouse model of metastatic lung cancer and glioblastoma with a specially designed system. METHODS: Tiny fragments of surgical tumors were implanted into the mice brain with a trocar system. Immunohistochemistry was performed to detect brain tumor stem cells among glioblastoma tissues, including both the original and resulting ones with monoclonal antibody against CD133. RESULTS: Besides the constant high take rates in both models; brain transplants perfectly resembled their original tumors in biological behaviors. The brain tumor stem cells, positively stained with CD133 were found, though not frequently, in both original and resulting glioblastoma tissues. CONCLUSIONS: Orthotopic model established with a trocar system is effective and injection of tumor tissues containing stem cells promise the forming of new tumor mass when grafted.

Di-µ-chlorido-bis-(chlorido{2,2'-[3-(1H-imidazol-4-ylmeth-yl)-3-aza-pentane-1,5-di-yl]diphthalimide}copper(II)).

The centrosymmetric dinuclear Cu(II) complex, [Cu(2)Cl(4)(C(24)H(21)N(5)O(4))(2)], was synthesized by the reaction of CuCl(2)·2H(2)O with the tripodal ligand 2,2'-[3-(1H-imid-azol-4-ylmeth-yl)-3-aza-pentane-1,5-di-yl]diphthalimide (L). Each of the Cu(II) ions is coordinated by two N atoms from the ligand, two bridging Cl atoms and one terminal Cl atom. The Cu(II) coordination can be best be described as a transition state between four- and five-coordination, since one of the bridging Cl atoms has a much longer Cu-Cl bond distance [2.7069 (13) Å] than the other [2.2630 (12) Å]. In addition, the Cu⋯Cu distance is 3.622 (1) Å. The three-dimensional structrure is generated by N-H⋯O, C-H⋯O and C-H⋯Cl hydrogen bonds and π-π inter-actions [centroid-centroid distances = 3.658 (4) and 4.020 (4) Å].

[Transplantation of human glioma stem cells in nude mice with green fluorescent protein expression].

OBJECTIVES: To investigate the possibility of transplantation of human glioma stem cells (HGSCs) in nude mice stably expressing green fluorescent protein (GFP) so as to clearly identify the incubated HGSCs from the host tissues. METHODS: Transgenic C57BL/6J mice expressing GFP was crossed with nude mice of the line NC, then hairless male nude mice expressing GFP were crossed with hairy female pubescent mice to obtain nude mice with GFP expression the expression of GFP in the skin and organs of these nude mice were evaluated by naked eyes, and immunohistochemical and immunofluorescence assays. HGSCs were transplanted orthotopically into the caudate nuclei of nude mice expressing GFP. Immunohistochemistry was used to observe the transplanted tumor. RESULTS: The structures rich in adipose tissue of the 8th generation nude mice were dark green and the other organs were light green. However, green fluorescence was emitted from all tissues under fluorescence microscopy. Confocal fluorescence microscopy showed that the tumor cells were stained red, distinguished from the host cells distinctly in the brains bearing tumor transplanted orthotopically. CONCLUSION: Nude mice expressing GFP can be obtained by crossing the transgenic mice bearing naive immunity with nude mice. Orthotopic transplantation of HGSCs may be used in the investigation of tumor tissue reconstitution because of the easy identification between the transplantation tumor and host tissue.

[Expression of SV40Tag, Rb and IRS-1 in glioma detected by tissue microarray and their relation with tumorigenesis and progression of gliomas].

OBJECTIVE: To determine the expression of SV40Tag, Rb and IRS-1 in gliomas and to identify their function in gliomagenesis and progression. METHODS: Tissue microarrays were constructed containing 118 samples including human glioma and meningioma, experimental glioma, and normal human brain tissue. The expression of SV40Tag, Rb, IRS-1, SV40Tag combined with Rb, and SV40Tag combined with IRS-1 were assayed by immunofluorescence or immunohistochemical techniques. The expression ratio and level were analyzed. RESULTS: The expressions of SV40Tag, Rb and IRS-1 were detected in gliomas and benign brain tumors. Their positive expression rate in glioma was 65.9%, 64.6% and 48.8%, respectively, with a statistically non-significant difference between the malignant and benign brain tumors. The malignant degree was positively correlated with SV40Tag and IRS-1, but negatively correlated with Rb expression. The combined expression rate of SV40Tag and Rb was 51.2%, and the combined expression rate of SV40Tag and IRS-1 was 40.2%. In the normal human brain tissue only the expression of Rb (77.8%, 7/9) and IRS-1 (22.2%, 2/9) were detected, but expression of SV40Tag could not be observed. CONCLUSION: Our findings that no expression of SV40Tag was observed in normal human brain tissue indicates that expression of SV40Tag may play an important role in the pathogenesis of glioma. It may be assumed that after SV40 virus invading human body, Rb disfunction and IRS-1 activation promote the malignant transformation of cells, which could be one of important factors in pathogenesis and procession of glioms.

Glioma stem cells are more aggressive in recurrent tumors with malignant progression than in the primary tumor, and both can be maintained long-term in vitro.

BACKGROUND: Despite the advances made during decades of research, the mechanisms by which glioma is initiated and established remain elusive. The discovery of glioma stem cells (GSCs) may help to elucidate the processes of gliomagenesis with respect to their phenotype, differentiation and tumorigenic capacity during initiation and progression. Research on GSCs is still in its infancy, so no definitive conclusions about their role can yet be drawn. To understand the biology of GSCs fully, it is highly desirable to establish permanent and biologically stable GSC lines. METHODS: In the current study, GSCs were isolated from surgical specimens of primary and recurrent glioma in a patient whose malignancy had progressed during the previous six months. The GSCs were cryopreserved and resuscitated periodically during long-term maintenance to establish glioma stem/progenitor cell (GSPC) lines, which were characterized by immunofluorescence, flow cytometry and transmission electronic microscopy. The primary and recurrent GSPC lines were also compared in terms of in vivo tumorigenicity and invasiveness. Molecular genetic differences between the two lines were identified by array-based comparative genomic hybridization and further validated by real-time PCR. RESULTS: Two GSPC lines, SU-1 (primary) and SU-2 (recurrent), were maintained in vitro for more than 44 months and 38 months respectively. Generally, the potentials for proliferation, self-renewal and multi-differentiation remained relatively stable even after a prolonged series of alternating episodes of cryopreservation and resuscitation. Intracranial transplantation of SU-1 cells produced relatively less invasive tumor mass in athymic nude mice, while SU-2 cells led to much more diffuse and aggressive lesions strikingly recapitulated their original tumors. Neither SU-1 nor SU-2 cells reached the terminal differentiation stage under conditions that would induce terminal differentiation in neural stem cells. The differentiation of most of the tumor cells seemed to be blocked at the progenitor cell phase: most of them expressed nestin but only a few co-expressed differentiation markers. Transmission electron microscopy showed that GSCs were at a primitive stage of differentiation with low autophagic activity. Array-based comparative genomic hybridization revealed genetic alterations common to both SU-1 and SU-2, including amplification of the oncogene EGFR and deletion of the tumor suppressor PTEN, while some genetic alterations such as amplification of MTA1 (metastasis associated gene 1) only occurred in SU-2. CONCLUSION: The GSPC lines SU-1 and SU-2 faithfully retained the characteristics of their original tumors and provide a reliable resource for investigating the mechanisms of formation and recurrence of human gliomas with progressive malignancy. Such investigations may eventually have major impacts on the understanding and treatment of gliomas.

Overexpression of CDC2/CyclinB1 in gliomas, and CDC2 depletion inhibits proliferation of human glioma cells in vitro and in vivo.

BACKGROUND: Gliomas are the most common and aggressive primary brain tumors for which unfortunately no effective treatment modalities exist despite advances in molecular biology as the knowledge base to unravel the extremely complex molecular mechanisms of tumorigenesis is limited. In this study an attempt has been made to understand the molecular pathological basis of tumorigenesis which led to an identification of an oncogene, CDC2, and an epigenetic strategy has been evaluated to control the tumorigensis by downregulating this oncogene. METHODS: Tissue microarrays were utilized to investigate the expression of genes in a large number of tumor samples and to identify overexpressed genes which could be potentially causing tumorigenesis. Retroviral vectors expressing short hairpin RNAs (shRNAs) targeted against CDC2 were designed and transducted into human glioma cell line ex vivo in order to downregulate the expression of CDC2. Real-Time PCR was used to determine the level of CDC2 mRNA. Western Blotting was used to determine the level of expression of CDC2 protein as measure to quantify down regulation of CDC2 expression along with use of flow cytometry to investigate effect of shRNAs on cell cycles and detection of apoptosis. Following ex vivo study, viral particles containing small interfering RNA for CDC2 were subsequently injected into xenogeneic graft tumor of nude mice and the weight of human glioma xenografts, survival and resulting phenotypic changes of target gene were investigated. RESULTS: Human glioma tissue microarrays indicated the positive expression rates of CDC2/CyclinB1 with a positive correlation with pathologic grades (r = 0.982, r = 0.959, respectively). Retroviral vectors expressing short hairpin RNAs (shRNAs) against CDC2 caused efficient deletion of CDC2, cellular G2/M arrest concluding in apoptosis and inhibition of proliferation in human glioma cells U251 and SHG-44 cell lines ex vivo. And the viral particles containing small interfering RNA for CDC2 were subsequently injected into subcutaneous and intracranial xenogeneic graft tuomrs of nude mice. For subcutaneous tumors, injection of CDC2-shRNA retroviruses significantly decreased tumor weight and volume compared with control. Immunohistochemistry indicated that CDC2 are negative and TUNEL are positive in tumors treated with recombinant retrovirus. For mice implanted with intracranial gliomas, treatment of CDC2-shRNA retroviruses increased survival times compared with control. CONCLUSION: CDC2 gene plays an important role in the proliferation of human gliomas. Downregulation of CDC2 could potentialy inhibit human gliomas cells growth ex vivo and in vivo. From these results, it was suggested that CDC2 might be a potential target on gene therapy of human gliomas.

1,1',5,5'-Tetra-methyl-2,2'-diphenyl-4,4'-[p-phenyl-enebis(methyl-idynenitrilo)]di-1H-pyrazol-3(2H)-one.

In the centrosymmetric title compound, C(30)H(28)N(6)O(2), the dihedral angles between the anti-pyrine ring and the terminal phenyl and central benzene rings are 50.55 (10) and 14.62 (9)°, respectively. Some short inter-molecular C-H⋯O inter-actions may help to establish the packing. An intramolecular C-H⋯O hydrogen bond is also present.

[Ultrastructural analysis of glioma stem cells-progenitors].

OBJECTIVE: It is well known that glioma stem cells-progenitors (GSCP) proliferate indefinitely and hardly differentiate in vitro, however, the reasons remain unknown. The aim of this study was to explore the ultrastructural basis of GSCP. METHODS: GSCP, kept by our laboratory, were collected, embedded, and cut into ultrathin sections and observed under the transmission electron microscope. RESULTS: A single GSCP usually had relatively well developed mitochondria, Golgi apparatuses, ribosomes, and undeveloped rough endoplasmic reticulum, but seldom lysosomes and no typical autophagosomes were found, and the nuclear-cytoplasmic ratio was high. The nuclei frequently contained huge amounts of euchromatin and a small quantity of heterochromatin, and in most nuclei there were only one nucleolus, however, two or more nucleoli were also common. Typical apoptotic cells could hardly be found in tumor-spheres, and between neighboring cells in tumor-spheres there were incompletely developed desmosomes or intermediate junction. CONCLUSION: The ultrastructural features of glioma stem cells-progenitors showed that BTSCP were very primitive and the lack of autophagy and the underdevelopment of some other cellular organelles are probably the reasons for the differential inhibition of GSCPs.

[CDK1 expression and effects of CDK1 silencing on the malignant phenotype of glioma cells].

OBJECTIVE: Our previous cDNA array data have shown that expression level of CDK1 increased along with the malignant progression of ganglioglioma, and decreased with the differentiation process of neural stem cells. The purpose of this study was to investigate the CDK1 expression levels in gliomas and the effects of CDK1 knockdown on phenotype of glioma cells. METHODS: Glioma tissue array was constructed, which was composed of surgical specimens of gliomas with different malignancy grades, glioma xenografts in nude mice, cellular spheroids of brain tumor stem cells, normal neural stem cells and glioma cell line. CDK1 expression was detected in glioma tissue array with immunohistochemical techniques. CDK1 expression in human brain glioma cell line and relevant xenogeneic graft tumor was inhibited by retroviral vectors expressing short hairpin RNAs (shRNAs). Both in vitro and in vivo changes of biological characteristics were further observed. RESULTS: The expression level of CDK1 increased along with the malignancy progression of glioma in clinical specimens. The positive expression rates of CDK1 in human brain glioma tissues were 22.2% (grade I), 40.0% (grade II), 69.6% (grade III) and 78.6% (grade IV), P = 0.01, respectively. The positive expression rate of CDK1 in glioma cell line and implanted xenografts was similar as the clinical tumors with high malignancy, and higher than those in neural stem cells and brain tumor stem cells (P = 0.0014). Expression of CDK1 was high in human fetal brain tissues and bone marrows of nude mice, but low in normal adult human brain tissues. Downregulation of CDK1 inhibited the proliferation activities notably both in SHG-44 cells in vitro and relevant xenogeneic graft tumors, and induced apoptosis of tumor cells prominantly as well. CONCLUSION: Overexpression of CDK1 may promote oncogenesis and progression of human gliomas. Downregulation of CDK1 expression can inhibit the proliferation activities of human malignant gliomas.

[Studies on the target cells and molecules with sodium valproate induced differential of human glioma cells].

OBJECTIVE: To investigate the target cells and molecules with sodium valproate induced differentiation of human glioma cells. METHODS: Nude mice bearing human glioma xenogenic graft subcutaneously were treated with sodium valproate. The expressions of HDAC1 and Tob genes of xenografts were analyzed with semiquantitative RT-PCR. The CD133+ cells (BTSCs) were isolated from glioma specimens by immunomagnetic sorting, and cultured in the medium containing FCS or in the serum-free medium supplemented with growth factors, respectively, followed by treatment with sodium valproate in vitro for 21 days. The cell surface markers were detected with flow cytometry and confocal microscopy. RESULTS: Sodium valproate inhibited the growth of subcutaneous xenografs bearing on nude mice (P<0.05), and up-regulated the HDAC1 expression (P<0.01), down-regulated the Tob expression (P<0.05). The cell surface markers of BTSCs were detected by flow cytometry after sodium valproate treatment for 21 days. In the FCS group, the GFAP or beta-tubulin III positive cells increased significantly (P<0.01), but in the growth factor group, no statistical differences were observed in the GFAP or beta-tubulin III expression (P>0.05). The results of confocal microscopy indicated that the GFAP+ or beta-tubulin III+ cells coexpressed with Nestin. CONCLUSIONS: HDAC1 and Tob genes were the potential target molecules in reversion of the differential inhibition of human glioma cells with sodium valproate. The BTSCs undergoing the processes of differentiation were the target cells for sodium valproate.

[Expression and significance of ABCG2 in human malignant glioma].

BACKGROUND & OBJECTIVE: ATP-binding cassette transporter protein ABCG2 is a marker derived from hematopoietic stem cells. However, its role in tumorigenesis and malignant progression of glioma is unclear. This study was to investigate the expression and significance of ABCG2 in gliomas of different malignant grades. METHODS: A microarray chip containing glioma tissues of different malignant grades, implanted glioma xenografts in nude mice, spheroids of glioma cell lines and glioma stem cells was prepared and examined for the expression of ABCG2 with immunohistochemical staining. RESULTS: The positive rate of ABCG2 was 26.8% in the 71 specimens of human glioma tissues, with 11.1% in grade I gliomas, 8% in grade II gliomas, 43.5% in grade III gliomas, and 42.9% in grade IV gliomas; it was significantly higher in grade III-IV gliomas than in grade I-II gliomas (chi2=10.710, P=0.001). The positive rate of ABCG2 was 100% in implanted glioma xenografts in nude mice, gliomas stem cells, and neural stem cells. It was also expressed in some normal tissues. The positive cells surrounded and invaded into vessels in glioma tissues. CONCLUSIONS: ABCG2 is overexpressed in glioma stem cells, glioma tissues of higher grades, and implanted glioma xenografts. The positive cells distribute around vessels in glioma tissues.