The effect of silencing Dicer by small interference RNA on the biological characteristics of human glioma cells / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the effect of silencing Dicer by small interference RNA (siRNA) to suppress the global microRNA (miRNAs) expression on the biological characteristics of TJ905 glioblastoma cells.</p><p><b>METHODS</b>The silencing effect of RNA interference on Dicer expression was evaluated by reverse transcription-polymerase chain reaction (RT-PCR), Western blot analysis and immunofluorescence staining. The cell proliferation rate and cell cycle kinetics were detected by MTT assay and flow cytometry respectively, and the cell invasive ability was evaluated by transwell assay.</p><p><b>RESULTS</b>The siRNA targeting Dicer suppressed the expression of Dicer in TJ905 cells. Meanwhile, the proliferation activity and invasive ability were significantly enhanced in cells transfected with Dicer siRNA compared to those cells transfected with scrambled siRNA and the control cells.</p><p><b>CONCLUSION</b>Suppression of Dicer expression renders the glioma cells harboring more aggressive phenotype. This preliminary finding suggests that global lower expression of miRNAs may play an oncogenic role.</p>

Inhibitory effect of knocking down microRNA-221 and microRNA-222 on glioma cell growth in vitro and in vivo / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To study the inhibitory effect of knocking down microRNA(miR)-221 and miR-222 on human glioma cell growth and its possible mechanism.</p><p><b>METHODS</b>miRNA-221/222 antisense oligonucleotides (antisense miR221/222) were transfected into human glioma U251 cells by lipofectamine. Northern blot analysis was conducted to detect the mRNA expression of miR-221/222 in the control and transfected cell groups. The proliferation activity of cells was determined by MTT assay. Cell invasion ability was examined by transwell assay, and cell cycle kinetics and apoptosis were detected with flow cytometry. The expression of relevant proteins was analyzed by Western blotting. The therapeutic efficacy of antisense miR221/222 on the growth of xenograft tumors in nude mice were also observed.</p><p><b>RESULTS</b>In the antisense miR-221/222-transfected cells, the expression of miR-221/222 was significantly reduced; the cell invasion ability was suppressed, cell cycle was blocked at G(0)/G(1) phase, and apoptotic cells were increased. The growth of xenograft tumors treated with antisense miR-221/222 was also inhibited. In antisense miR-221/222 treated tumor cells, the expression of bcl-2 was down-regulated while connexin43, p27, PUMA, caspase-3, PTEN, TIMP3 and Bax up-regulated, and p53 expression not changed.</p><p><b>CONCLUSION</b>There is a significant inhibitory effect of antisense miR-221/222 on the growth of human glioma U251 cells. miR-221/222 may be considered as a candidate target for gene therapy of human gliomas.</p>

Study on the anti-invasion effect of SEPT7 gene for U251MG glioma cell in vitro / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the anti-invasion effect of SEPT7 gene on U251MG glioma cells and its possible molecular mechanism.</p><p><b>METHODS</b>Recombinant adenovirus vector carrying SEPT7 gene (rAd5-SEPT7) was transduced to human glioma cell line U251MG, and empty adenovirus vector was used as control. Tumor invasion was examined by Transwell method and 3 D-Matrigel assay, and tumor cell migration by wound-healing method and 2 D-Matrigel assay. Three major molecular events associated with cell motility and migration, including changes of expression in MMP2, MMP9, MT1-MMP, TIMP1 and TIMP2, the alteration of integrin alpha(v)beta(3) expression, and the structural change of cytoskeleton protein, tubulin-alpha, in U251 cells transduced with rAd5-SEPT7 were studied by Western blotting, immunofluorescence and laser scanning confocal microscope, respectively.</p><p><b>RESULTS</b>The invasive and migratory capabilities of cells transduced with rAd5-SEPT7 were inhibited. The expression of extracellular matrix metalloproteinases MMP-2, MMP-9, MT1-MMP and integrin alpha(v)beta(3) was significantly decreased, while the expression of matrix metalloproteinase inhibitor TIMP1, TIMP2 was upregulated. Intracellular cytoskeleton protein-tubulin-alpha in U251 cells exhibited prominent morphological changes which including the appearance of distortion and aggregation resulting from redistribution of tubulin-alpha, and this feature of alteration was similar to the tubulin-alpha structure in normal non-tumor cells.</p><p><b>CONCLUSION</b>SEPT7 gene can inhibit the invasion and migration ability of U251 glioma cells. Its molecular mechanism may include that SEPT7 gene reverses the imbalanced state of MMPs/TIMPs, downregulates the expression of integrin alpha(v)beta(3) and alters the structure of tubulin-alpha of U251MG glioma cells. It is suggested that SEPT7 gene could be a good candidate for gene therapy of gliomas.</p>

Differential expression of Notch1 and Notch2 in astrocytoma and medulloblastoma / 中华病理学杂志

<p><b>OBJECTIVE</b>To detect the differential expression of Notch1 and Notch2 in human astrocytoma and medulloblastoma; and to study the role of Notch1 and Notch2 in the development of both tumors.</p><p><b>METHODS</b>Immunohistochemical staining (SP method) and Western blot analysis were used to detect Notch1 and Notch2 expression in tissue arrays and freshly resected samples of normal brain tissue, astrocytoma and medulloblastoma.</p><p><b>RESULTS</b>Notch1 and Notch2 were negative in normal human brain tissue. Notch1 was highly expressed (total positive rate 80.0%, 48/60) while Notch2 was not detected in grade IV astrocytomas and sporadically observed in lower grade astrocytomas (total positive rate 10.0%, 6/60). The percentage of positive tumor cells and expression level of Notch1 increased with higher histologic grade (r = 0.859, P < 0.05). On the other hand, overexpression of Notch2 was detected in medulloblastoma (9/10) in contrast with lower expression of Notch1 (2/10).</p><p><b>CONCLUSIONS</b>Notch1 and Notch2 show differential expression in astrocytoma and medulloblastoma. This may be related to their different functional activities during the process of brain development.</p>

Influence of SEPT7 on biological characters of glioma cell line TJ905 / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the influence of SEPT7 on biological characters of gliomas cells TJ905.</p><p><b>METHODS</b>Recombinant SEPT7 constructs was transfected to human glioblastoma cell line TJ905 in which SEPT7 expression is absent. The positive clones were identified by RT-PCR and Western blot analysis. The cell proliferation was determined by MTT assay and flow cytometry, cell apoptosis was detected with Annexin V staining and cell invasion was evaluated by motility in three-dimensional culture. Moreover, the molecules regulating the cell cycle progression were examined by immunofluorescence staining and Western blot analysis.</p><p><b>RESULTS</b>When SEPT7 was successfully transfected to TJ905 cells, the cell proliferation activity of TJ905 cell was inhibited, the cell cycle was arrested in G0/G1 phase and S phase fraction (SPF) was lowered, the positive regulatory molecules for cell cycle progression including cyclin D1, CDk4, cyclin E and CDk2 were downregulated while the negative modulators including p16 and p21 were upregulated, apoptotic cells were increased and cell invasive ability was attenuated.</p><p><b>CONCLUSIONS</b>Transfection of SEPT7 construct into the glioma cells TJ905 is able to inhibit the proliferation activity and invasive ability of TJ905 cell and to induce cell apoptosis. These results revealed that SEPT7 exerted the suppressive effect on the glioma cell growth and invasion, and induced apoptosis, and suggested that SEPT7 as a gene of glioma suppressor.</p>

Study on the expression of epidermal growth factor receptor and p53 in astrocytic gliomas: evidence for a distinct genetic pathway / 中华病理学杂志

<p><b>OBJECTIVE</b>To study further the most important and frequent genetic alterations of p53 and epidermal growth factor receptor (EGFR) in astrocytic gliomas.</p><p><b>METHODS</b>(1) EGFR expression was examined in samples collected from 37 astrocytic gliomas and 6 normal brain tissue using reverse transcriptase polymerase chain reaction and immunohistochemical staining. (2) p53 gene mutation and accumulation were detected simultaneously in the same specimens using PCR-SSCP, DNA sequencing and immunohistochemical staining.</p><p><b>RESULTS</b>The frequency of p53 mutation in diffuse astrocytomas, anaplastic astrocytomas, primary glioblastomas and secondary glioblastomas was 1/10, 4/19 (21.1%), 4/6 and 2/2, respectively and the frequency of EGFR overexpression was 5/10, 10/19 (52.6%), 5/6 and 2/2, respectively. Both p53 accumulation and EGFR overexpression increased accompanied by a successive increase of degree of the glioma malignancy.</p><p><b>CONCLUSIONS</b>EGFR overexpression is not infrequently seen, however, p53 mutation is rarely seen in the low grade gliomas. Both p53 gene mutation and EGFR overexpression are often associated with primary and secondary glioblastoma. Consequently, EGFR overexpression and p53 gene mutation are not mutually exclusive in astrocytic gliomagenesis but synergistically to promote the glioma progression.</p>

Preliminary study on the gene expression profiles of ependymomas with cDNA array / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the differential gene expression of ependymomas.</p><p><b>METHODS</b>Four fresh samples of ependymomas and 1 of normal brain tissue were collected during operation. The extracted total RNAs were converted as (32)P tagged cDNA probes, which were then hybridized with the Atlas Human Cancer Array, producing the array based hybridization maps following the protocol provided with the kit. A set of special software was applied to the analysis and RT-PCR was performed to test the result.</p><p><b>RESULT</b>In comparison with the normal brain tissue, there were 31 upregulated gene and 1 downregulated gene in ependymomas, most of which were firstly found to be differentially expressed in this kind of tumor.</p><p><b>CONCLUSION</b>The discrepancy of gene expression profiles between ependymomas and normal brain tissues is highly put through and effectively detected with cDNA array, which provides new information for the further research on the molecular mechanisms of this lesion.</p>

Preliminary study on the mechanism of connexin 43 gene transfection in the control of glioma cell proliferation / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To study the mechanism involved in the control of glioma cell proliferation with transfection of connexin (Cx) 43 gene.</p><p><b>METHODS</b>C6 rat glioma and TJ905 human glioblastoma cell lines without Cx43 gene expression were transfected with Cx43cDNA mediated by lipofectamine. Northern blot, in situ hybridization and immunohistochemical technology were used to detect the expression of Cx43mRNA and its protein with MTT assay and silver colloid stain for the detection of cell proliferation, TUNEL method for determination of cell apoptosis, scrape loading dye transfer (SLDT) for GJIC, Western blot and immunohistochemical technology for bFGF, PDGF, EGFR, IGF-I and IGFBP3 expression.</p><p><b>RESULTS</b>Cx 43 gene transfected glioma cells showed decreased proliferation, restored GJIC and decreased bFGF, PDGF, IGFBP3, except EGFR expression and cell apoptosis which showed no change.</p><p><b>CONCLUSION</b>The mechanism of Cx 43 gene inhibiting gliomas cell proliferation is the restoration of GJIC and decreased autocrine growth factors.</p>