[Relationship between miR-218 and CDK6 expression and their biological impact on glioma cell proliferation and apoptosis].

OBJECTIVES: To investigate the relationship between the expression of miR-218 and CDK6 in glioma cells, and their biological impacts on the tumor cell proliferation and apoptosis. METHODS: Expression levels of miR-218 as well as CDK6 and Ki-67 proteins were analyzed in 60 cases of gliomas with various grades and 10 control brain tissue samples by tissue microarray, locked oligonucleotide probe in situ hybridization and immunohistochemistry. Glioblastoma multiform cell line (U87MG) was transfected with miR-218 mimics (mimics group) and a control sequence (control group), followed by qRT-PCR detection of miR-218 and immunocytochemical stain of CDK6 and Ki-67, respectively. Single cell gel electrophoresis was used to detect the presence of apoptotic cell. RESULTS: The miR-218 labeling indexes (LI) were statistically different (P<0.05) among all groups including control (22.45 +/- 0.59) and various glioma groups (grades I - II 4.00 +/- 1.07, grade III 1.87 +/- 1.06 and grade IV 0.94 +/- 0.78, respectively). The CDK6 LI of the four groups was 7.25 +/- 1.20, 16.71 +/- 0.80, 24.43 +/- 0.62 and 32.05 +/- 0.43, respectively. Significant differences existed between the control group and the glioma groups, and between grade IV and grades I - II glioma groups (P<0.01). Ki-67 positive cell densities of the above four groups (0.00 +/- 0.00, 9.30 +/- 3.48, 31.15 +/- 9.44 and 60.15 +/- 13.60) were significantly different from one and another (P<0.01). The expression of miR-218 negatively correlated with CDK-6 LI (r = -0.480, P<0. 01) and Ki-67 positive cell density (r = - 0.534, P<0.01), while the latter two positively correlated with each other (r = 0.530, P<0.01). U87MG transfection experiment showed that the miR-218 level of the mimics group was significantly higher than that of the control group (P<0.01). CDK6 and Ki-67 LI of the mimics group (14.74 +/- 1.19 and 30.88 +/- 3.31) were significantly lower than those of the control group (79.06 +/- 2.07 and 64.94 +/- 3.96, P<0.01), whilst its apoptotic index (AI) (68.44 +/- 7.05) was significantly higher than that of the control group (13.04 +/- 0.97, P<0.01). CONCLUSIONS: The expression level of miR-218 is an important reference indicator for the assessment of the grade of gliomas. An aberrant decrease of its expression may lead to an increase of the CDK6 expression and proliferative activity of giloma cells. Introducing exogenous miR-218 may effectively down-regulate the CDK6 expression, inhibit cell proliferation and induce apoptosis of malignant giloma cells. These findings imply that miR-218 may serve as a therapeutic agent against malignant glioma.

[Detection of chromosomal DNA imbalance in medulloblastoma by comparative genomic hybridization].

OBJECTIVE: To investigate the relationship between chromosomal genomic DNA imbalance in medulloblastoma (MB), and the age and gender. METHODS: The gains and losses of chromosomal genomic DNA in 16 MBs were analyzed using comparative genomic hybridization. RESULTS: The gains and(or) losses were found in 15 of the 16 cases. There was not significant difference (P > 0.05) between the total gains (10/16) and losses (11/16). Both of their differences had also no significance between different age and gender groups (P > 0.05). In 15 cases with gains and(or) losses, single-, two-, three- and multi-chromosome genomic DNA imbalances were 3/15, 4/15, 1/15 and 7/15 respectively. Eleven gain zones (+5q, +6q, +7q, +11q, +15q, +17p, +17q, +19q, +20q, +21q, +Xp) and twenty-five loss zones (-1p, -1q, -2p, -2q, -3q, -4p, -6p, -6q, -8p, -8q, -10p, -10q, -11p, -14q, -16p, -16q, -17p, -18p, -18q, -19p, -19q, -20p, -20q, -Xp, -Xq) were detected in those tumors. +7q (6/16), +17q (6/16), -14q (5/16) and -10q (3/16) were the most frequent, but -14q only occurred in the cases of > 10-year-old. CONCLUSIONS: Most MBs have chromosomal genomic DNA imbalances. The frequent imbalance zones are mainly at the long arms of some chromosomes. +7q, +17q, -14q and -10q correlate closely to development of the tumors. -14q is important factor to result in MBs of > 10-year-old group. MB has possibly different molecular genetics subtype.

[Effects of azidothymidine on p33ING1b expression, apoptosis and senescence of TJ905 human glioblastoma cell line].

OBJECTIVES: To investigate the pharmacological effects of azidothymidine (AZT) on p33ING1b expression, senescence and apoptosis of TJ905 glioblastoma cells. METHODS: TJ905 cells were treated with AZT at a serial concentrations of 50, 100 and 200 µmol/L. Semi-quantitative RT-PCR and cytochemical staining of senescence related-galactosidase (sß-Gal) were used to evaluate the expression of p33ING1b mRNA and to label the senescent cells at the 1st, 3rd and 6th generations, respectively. In situ cell death detection and single cell gel electrophoresis were used to detect the apoptosis at the 3rd and 6th generations. RESULTS: AZT induced the expression of p33ING1b mRNA and senescence of the tumor cells of the 1st generation in a dosage and time dependent manner. At the 6th generation, the relative amount of p33ING1b RT-PCR product (1.44±0.23) and sß-Gal labeling index of 200 µmol/L group (45.62±6.74) were significantly higher than those of the 1st (0.95±0.13 and 7.82±2.40) and the 3rd generation cells (1.35±0.23, 26.27±7.17) of the same group, and cells of the same generation in the 50 µmol/L (0.85±0.24, 27.37±6.41) and 100 µmol/L groups (1.23±0.34, 35.49±5.12, P<0.01). There was a significant positive correlation between the p33ING1b mRNA expression and the labeling index of sß-Gal. Pro-apoptotic effects of AZT became obvious at the 6th generation. CONCLUSION: AZT upregulates the expression of p33ING1b, a possible mechanism in regulating senescence and apoptosis of the TJ905 cells.

[Detection of chromosomal imbalance in ependymoma by comparative genomic hybridization].

OBJECTIVE: To investigate genomic DNA imbalances in ependymomas (EDMs) and their correlations with the tumor histological types, grades, locations, patients' gender and age. METHODS: Chromosomal gains and losses in 16 cases of EDM were analyzed using comparative genomic hybridization. RESULTS: Chromosomal regional gain and loss were found in 15 and 13 of 16 EDM cases respectively including totally 24 regional gains and 19 regional losses in all the tumors studied. Both regional gains and losses were mostly seen in myxopapillary EDMs (MPE, WHO grade I), more commonly seen in cellular EDMs (CE, WHO grade II) and tanycytic EDMs (TE, WHO grade II) than in anaplastic EDMs (AE, WHO grade III). Some of the regional gains and losses appeared only in one subtype of MPE, CE, TE and AE cases resulting in development of specific imbalance profiles of certain subtype in these cases. MPE, CE and TE often had +7. Chromosomal +5 occurred only in MPE and CE, and -22q was only seen in CE and TE. AE frequently had +1q, but none had +5, +7, -4q, -19q and -22q. The frequencies of any regional gain or loss were not affected by patients' genders (P > 0.05). Chromosomal +1q and +7p happened predominantly in intracranial EDMs with an averagely onset age of

[Azidothymidine inhibition of telomerase activity and proliferation of TJ905 human glioblastoma cells].

OBJECTIVE: To investigate the pharmacological effects and underlying mechanism of azidothymidine (AZT) on human glioblastoma cells in vitro. METHODS: The telomerase activity of human glioblastoma TJ905 cells was determined by TRAP assay after 24 hrs' incubation with 50, 100, 200 micromol/L AZT and control vehicle solution. Colony formation efficiencies of the cells were recorded. Cells of the 1st, 3rd and 6th generations were harvested, followed by evaluations of cyclin A protein expression by Western blot, cell cycle distribution by flow cytometry, apoptotic level by single cell gel electrophoresis and proliferation index by Ki-67 immunocytochemical staining. RESULTS: AZT inhibited telomerase activity of TJ905 cells. Cyclin A expression levels in the cells treated with 50 and 100 micromol/L AZT were significantly lower than controls (P < 0.01), and down-regulation of the expression was in a dose- and time-dependent manner. Compared with controls, G(0)/G(1) phase cells were obviously decreased (P < 0.05 approximately 0.01) and S phase cells significantly increased (P < 0.05 approximately 0.01) after treatment with 50, 100 and 200 micromol/L AZT. The cell numbers of G(0)/G(1) and S phases at the 1st generation of above three treated groups changed in a dose-dependent manner, whereas S phase cells increases in all AZT treatment groups and G(0)/G(1) phase cell decrease in group treated with 50 micromol/L AZT were also in a time-dependent manner. Both the apoptotic cells of the 1st and 6th generations of all AZT treatment groups were significantly more than controls (P < 0.05 approximately 0.01), their numbers of the 6th generations of the three groups increased with AZT concentration (P < 0.05 approximately 0.01), and all of them were more than the 1st and 3rd generations of the same dosage group (P < 0.05 approximately 0.01). Colony formation efficiencies and Ki-67 labeling indexes of the three AZT treatment groups were distinctly lower than controls (P < 0.01), and they were also decreased with the elevation of AZT concentration and/or the elongation of the incubating time. The difference of any above parameter had no significance among the 1st, 3rd and 6th generations of control group (P > 0.05). CONCLUSION: AZT blocks S/G(2) conversion of TJ905 cells by inhibition of telomerase activity and cyclin A expression, leading to an enhancement of apoptosis and suppression of cell proliferation.

[Expression vector for the inhibitor of growth-1 gene is constructed and the NLS-GFP fusion protein expresses in MRC-5 cells].

OBJECTIVE: To construct the NLS(ING1)-GFP vector, transfer it into MRC-5 cells and establish a cell model expressing NLS (ING1)-GFP fusion protein. METHODS: Firstly, cDNA fragment of nuclear locating sequence (NLS) of inhibitor of growth-1 gene (ING1) was gained by RT-PCR and inserted into multi-clone site of pEGFP-C1 to construct the NLS (ING1)-GFP expression vector. Then the vector was used to transfect the MRC-5 cells to observe the subcellular signal localization of green fluorescence protein (GFP). RESULTS: We successfully constructed the expressing vector of NLS (ING1)-GFP fusion protein. After transferring the fusion expressing vector into MRC-5 cells, we observed that green fluorescence signal located in the cell nucleus. However, the green fluorescence signal located in the cytoplasm in MRC-5 cells transfected with pEGFP-C1 control only expressing GFP. CONCLUSION: In living cells, physiologically p33 ING1b locates absolutely in nucleus. The p33(ING1b) NLS plays a decisive role in the transporting process of subcellular localization.

[Effects of caspase-3 inhibitor on the neuronal apoptosis in rat cerebral cortex after ischemia-reperfusion injury].

OBJECTIVE: To investigate the effect of z-DEVD-fmk, a caspase-3 inhibitor on the neuronal apoptosis in ischemia-reperfusion region (IRR) of rat cerebral cortex. METHODS: Rats prepared by middle cerebral artery occlusion and reperfusion were used as the research model. The animals were divided into A group (untreated), B group (DMSO control) and C group (treated with z-DEVD-fmk). Before reperfusion, z-DEVD-fmk (7 microg/kg) was injected into the ischemic side of ventriculus cerebri of C group rats. The expression and activation of caspase-3, expression and cleavage of poly (ADP-ribose) polymerase (PARP), and apoptotic neurons in the temporal-parietal cortex IRRs (SPAB method) of all the rats were studied using Western blotting, in situ apoptotic detection (TUNEL method) and immunohistochemistry. RESULTS: In the cerebral IRRs of A, B, C groups reperfused for 1 h and 24 h, the quantities of caspase-3 precursor were 16.7 +/- 3.0, 11.5 +/- 3.0 and 47.5 +/- 3.5, and 76.1 +/- 3.5, 71.3 +/- 6.4 and 88.2 +/- 5.5, respectively; the caspase-3 fragments (12,000) 8.2 +/- 2.3, 9.4 +/- 1.2 and 4.3 +/- 1.6, and 59.0 +/- 6.3, 60.5 +/- 7.2 and 17.3 +/- 2.8, respectively; the PARP 12.6 +/- 3.0, 13.9 +/- 2.0 and 53.7 +/- 4.1, and 67.5 +/- 8.6, 61.1 +/- 6.6 and 93.6 +/- 4.1, respectively; the PARP fragments (24,000) 6.0 +/- 0.7, 6.6 +/- 1.2, 3.6 +/- 1.1, and 27.4 +/- 2.6, 25.8 +/- 3.2, 12.1 +/- 2.8 (relative quantity, x+/- s); the densities of apoptotic neurons 83.3 +/- 7.5, 84.3 +/- 5.7 and 45.7 +/- 4.0, and 197.4 +/- 11.8, 185.2 +/- 11.2 and 99.1 +/- 5.8 (cell number/0.1 mm(2), x+/- s). These results showed that in the cerebral IRRs of both A and B groups, all caspase-3 expression and activation, PARP expression and cleavage, and neuronal apoptosis were increased relevantly along with prolongation of the reperfusion time (P < 0.05 - 0.001). At each time point of the reperfusion, caspase-3 activation, PARP cleavage and neuronal apoptosis in the cerebral IRR of C group were significantly less than those of the former two groups (P < 0.05 - 0.001). The variations of the 5 parameters of A, B and C groups correlated positively with one another (r = 0.630 - 0.942, P < 0.01). The cells expressing PARP were mainly neurons in the cerebral IRRs of all the animals, but the difference of their number was not distinct among the 3 groups. CONCLUSIONS: It is an important mechanism resulting in apoptosis of the injured neurons in the cerebral IRR that caspase-3 expression and activation abnormally increased by the reperfusion have more PARP rapidly inactivated by over-cleavage. z-DEVD-fmk may decrease PARP cleavage by inhibiting activity and auto-activation of caspase-3, and prevent the injured neurons from apoptosis.

[Study on expression of ING1, human telomerase reverse transcriptase and telomerase-associated protein 1 genes in human gliomas].

OBJECTIVE: To investigate the relationship between expressions of ING1 gene and genes of human telomerase reverse transcriptase (hTERT) and telomerase-associated protein 1 (hTP1) in human gliomas. METHODS: The expressions of ING1 mRNA and p33(ING1) protein, hTERT mRNA and protein, and hTP1 mRNA and protein in seventy human glioma specimens with different malignant grades were studied using in situ hybridization and immunohistochemistry. RESULTS: All of the 70 gliomas collected expressed hTP1 mRNA and protein and among them, 62 (88.6%) and 58 (82.9%) out of 70 expressed hTERT mRNA and protein respectively. The quantities of the four kinds of positive cells were correlated positively with one another (r = 0.758 - 0.882, P < 0.000 5), and all of them were significantly fewer in gliomas of WHO grade I - II than in grade III gliomas and the most in grade IV gliomas (P < 0.05 approximately 0.01). 66 (94.3%) and 62 (88.6%) out of 70 gliomas expressed ING1 mRNA and p33(ING1) protein respectively. The quantities of their positive cells were also correlated positively with each other (r = 0.831, P < 0.000 5), but the positive cells were more in gliomas of WHO grade I - II than in grade III gliomas and the fewest in grade IV gliomas (P < 0.01). The quantities of positive cells of ING1 mRNA and p33(ING1) protein were correlated negatively with those of hTERT mRNA and protein as well as hTP1 mRNA and protein respectively (r = -0.211 to -0.384, P < 0.05 approximately 0.001). CONCLUSIONS: The results suggest that all of the parameters concerned are valuable in evaluating the biological behavior of gliomas. In glioma cells, overexpressions of hTERT and hTP1 genes might be significant in inhibiting the expression of ING1 gene. The abnormal expressions of the three genes play possibly the important roles in the development and malignant progression of gliomas.