Cytochalasin B inhibits the proliferation of human glioma U251 cells through cell cycle arrest and apoptosis

Cytochalasin B (CB) is known to inhibit a number of cancer types, but its effects on gliomas are unknown. We examined the in vitro effects of CB on the proliferation of human glioma U251 cells, as well as determined its mechanism of action. Cell proliferation was determined using CCK-8. The effect of CB on U251 cell morphology was observed under a transmission electron microscope. Cell cycle distribution was assessed using propidium iodine and Giemsa staining, and cell apoptosis was determined by annexin V-fluorescein isothiocyanate/propidium iodide. Cell cycle-related proteins were determined by Western blot. CB effectively inhibited U251 cell proliferation in a dose- and time-dependent manner. The 24, 48, 72, and 96 h IC50 values were 6.41 x 10(-2), 9.76 x 10(-4), 2.57 x 10(-5), and 2.08 x 10(-5) M, respectively. CB increased the proportion of cells in the G2/M phase in a dose-dependent manner, thus increasing the mitotic index and decreasing cdc2 and cyclin B1 protein levels. CB induced morphological changes in the cytoskeleton. Additionally, 10(-5) M CB induced apoptosis in 23.4 ± 0.5% of U251 cells (P < 0.05 vs control group). Caspase-3, -8, and -9 activities were increased after CB treatment. CB inhibited U251 glioma cell proliferation by damaging the microfilament structure. CB also induced glioma cell apoptosis, suggesting that it may be an effective therapeutic agent against gliomas.

Impact of MTHFR polymorphisms on methylation of MGMT in glioma patients from Northeast China with different folate levels

Hypomethylation of the O6-methylguanine-DNA-methyltransferase (MGMT) promoter in glioma cells has been associated with temozolomide resistance. S-adenosylmethionine (SAM), which is produced during folate metabolism, is the main source of methyl groups during DNA methylation. As a key enzyme during folate metabolism, polymorphisms of 5,10-methylenetetrahydrofolate reductase (MTHFR) may regulate folate end-products. We investigated the effect of typical polymorphisms of MTHFR (C677T and A1298C) on MGMT methylation based on different serum folate levels in patients with glioma from Northeast China. A total of 275 patients with glioma and 329 without malignant tumors were tested. Serum folate concentration was assayed by using the electrochemiluminescence immunoassay. MTHFR polymorphisms were detected by Taqman-Fluorescence quantitative polymerase chain reaction (PCR). Methylation-specific PCR was used to assess MGMT methylation. The constituent ratio of glioma patients below the serum folate biological reference value was significantly higher than that of the control population (P < 0.001). In patients with oligodendroglioma and glioblastoma, heterozygotes for the A1298C mutation were found in higher frequency than homozygotes or wild types (oligodendroglioma, P < 0.001; glioblastoma, P < 0.01). When grouped by the median or biological reference value of serum folate, only homozygotes for C677T with low levels of folate were significantly associated with decreased methylation of MGMT (median, P < 0.001; biological reference value, P = 0.036). These data suggest that, in combination with a negative folate balance in glioma patients, T/T genotypes in MTHFR C677T may be associated with MGMT demethylation.

Assessment of lateral geniculate nucleus atrophy with 3T MR imaging and correlation with clinical stage of glaucoma

BACKGROUND AND PURPOSE

Although previous animal studies have shown structural changes in ocular hypertension such as atrophy of the LGN, such changes have not been thoroughly studied in human glaucoma patients nor correlation made with clinical stage. Our aim was to investigate prospectively LGN atrophy in patients with POAG using 3T MR imaging and correlation with the clinical stage of disease.

MATERIALS AND METHODS

Twenty-six patients with known POAG and 26 age-matched healthy volunteers were included in this institutional review board-approved study. All subjects underwent imaging on a 3T MR imaging system with a PD and GM sequence. LGN height and volume were measured by 2 blinded neuroradiologists. Measurements were compared and correlated with clinical glaucoma severity as assessed by static threshold visual field parameters.

RESULTS

Average maximum LGN height in patients with glaucoma on PD images was 4.36 ± 0.61 mm (right) and 4.31 ± 0.61 mm (left), significantly less (P < 10⁻³) than respective measurements of 5.05 ± 0.41 and 4.99 ± 0.41 mm in volunteers. With the GM sequences, such respective measurements were also less (P < 10⁻³) in patients with glaucoma (4.20 ± 0.71 mm right, 4.00 ± 0.85 mm left) versus respective measurements in volunteers (4.88 ± 0.51 mm right, 4.77 ± 0.47 mm left). Average LGN volumes in the patient group were 98.0 ± 27.2 mm³ (right) and 93.7 ± 25.8 mm³ (left) with the PD sequence versus respective measurements of 85.2 ± 27.1 and 80.5 ± 23.6 mm³ with the GM sequence. All height and volume measurements were greater in volunteers (P < 10⁻³). In the patient group, both maximum height and volume of the LGN with both sequences were significantly correlated with cumulative clinical glaucoma stage (P < .05).

CONCLUSIONS

MR imaging measurements of LGN height and volume are diminished in patients with glaucoma, with the extent of atrophy correlating to clinical stage, suggesting a novel imaging marker of disease severity.

Human Gastric Adenocarcinoma Allelotype on Chromosomes 17 and 18

Allelic losses of multiple chromosome loci in gastric adenocarcinoma suggest that inactivation of tumour suppressor genes in these regions may be important for tumourigenesis. To define deletion intervals and find candidate tumour suppressor genes involved in gastric adenocarcinoma pathogenesis, a genome-wide search for loss of heterozygosity (LOH) was conducted in 45 patients with primary gastric adenocarcinoma. Investigations using 29 microsatellite markers spanning chromosomes 17 and 18 showed allelic deletion in 29 (64%) specimens at one or more loci. Five LOH overlap regions, three newly identified as deletion regions, were defined: RI, D17S831–D17S921 at 17p12-13.3; RII, D17S1868–D17S787 at 17q21.3-22; RIII, D17S785–D17S928 at 17q25.3; RIV, D18S61–D18S1161 at 18q22; and RV, D18S462–D18S70 at 18q22-q23. Eleven (24%) patients with chromosome 17 allelic loss also showed LOH on 18q, with at least one region of overlapping. LOH mapping showed allelic losses were widespread on both chromosomes and suggests the possibility that multiple tumour suppressor genes, including one or more that are unknown, might be inactivated in the aetiology of gastric adenocarcinoma.

A mathematical model of P53 gene regulatory networks under radiotherapy

P53, a vital anticancer gene, controls the transcription and translation of a series of genes, and implement the cell cycle arrest and cell apoptosis by regulating their complicated signal pathways. Under radiotherapy, cell can trigger internal self-defense mechanisms in fighting against genome stresses induced by acute ion radiation (IR). To simulate the investigating of cellular responding acute IR at single cell level further, we propose a model of P53 gene regulatory networks under radiotherapy. Our model can successfully implement the kinetics of double strand breaks (DSBs) generating and their repair, ataxia telangiectasia mutated (ATM) activation, as well as P53-MDM2 feedback regulating. By comparing simulations under different IR dose, we can try to find the optimal strategy in controlling of IR dose and therapy time, and provide some theoretical analysis to obtain much better outcome of radiotherapy further.

[Catheter dilatation of arterial stenoses of supra-aortic vessels and late results]

Arterial stenoses of supra-aortic vessels, particularly of the subclavian and vertebral arteries, can be successfully treated by percutaneous transluminal angioplasty (PTA). In 125 patients primary success was achieved in 93% by PTA; 84 patients have been followed up for an average of 46 months and a clinical cure rate of 98.8% has been achieved. Apart from one re-stenosis all patients were symptom free and no other re-stenoses could be demonstrated. PTA of occlusions of supra-aortic vessels has less chances of success.