Oxidative stress inhibits growth and induces apoptotic cell death in human U251 glioma cells via the caspase-3-dependent pathway

OBJECTIVE

To investigate the possible pathway involved in hydrogen peroxide (H2O2) induced apoptosis in U251 glioma cells.

MATERIALS AND METHODS

The cultured U251 glioma cells were used in this study. The cells were divided into three groups: control group (untreated glioma cells), H2O2 group (treated with 100, 300 and 500 µM H2O2) and CI group (treated with 300 µM H2O2 and 15 µM caspase inhibitor, CI). The cellular viability was determined by MTT [3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide] assay. A flow cytometer was used for measuring the cell cycles. The mode of cell death was assessed by Annexin-V/PI-flow cytometry analysis. Fluorescence dihydroethidium (DHE) method was conducted to detect the oxygen species (O2-). Western blot analysis was performed to confirm the pro-caspase-3, caspase-3 and PARP (poly-ADP-ribose polymerase) protein expression.

RESULTS

The oxidative stress to U251 glioma cells exhibited in a dose-dependent manner with H2O2 concentrations increasing. The cell viability was considerably decreased and apoptosis occurred in H2O2 treated cells. A G1 cell cycle arrest and O2- level increase were found in H2O2 group. Western blot analysis showed a decrease of pro-caspase-3 protein level and an increase of caspase-3 and PARP level in 300 µM H2O2 treated cells. The H2O2 induced apoptosis depicted above was significantly restrained by CI.

CONCLUSIONS

Oxidative stress inhibits growth and induces apoptotic cell death in human U251 glioma cells via the caspase-3-dependent pathway. Mitochondrial pathway might involve in this signaling conduction. These findings are favorable for understanding the mechanisms of oxidative stress-induced apoptosis in U251 glioma cells.

Altered mesenchymal niche cells impede generation of normal hematopoietic progenitor cells in leukemic bone marrow

Degeneration of normal hematopoietic cells is a shared feature of malignant diseases in the hematopoietic system. Previous studies have shown the exhaustion of hematopoietic progenitor cells (HPCs) in leukemic marrow, whereas hematopoietic stem cells (HSCs) remain functional upon relocation to non-leukemic marrow. However, the underlying cellular mechanisms, especially the specific niche components that are responsible for the degeneration of HPCs, are unknown. In this study, we focused on murine bone mesenchymal stem cells (MSCs) and their supporting function for normal hematopoietic cells in Notch1-induced acute T-cell lymphocytic leukemia (T-ALL) mice. We demonstrate that the proliferative capability and differentiation potential of T-ALL MSCs were impaired due to accelerated cellular senescence. RNA-seq analysis revealed significant transcriptional alterations in leukemic MSCs. After co-cultured with the MSCs from T-ALL mice, a specific inhibitory effect on HPCs was defined, whereas in vivo repopulating potential of normal HSCs was not compromised. Furthermore, osteoprotegerin was identified as a cytokine to improve the function of T-ALL MSCs and to enhance normal HPC output via the p38/ERK pathway. Therefore, this study reveals a novel cellular mechanism underlying the inhibition of HPC generation in T-ALL. Leukemic MSCs may serve as a cellular target for improving normal hematopoietic regeneration therapeutically.

Development of an ultrasensitive immunochromatographic assay (ICA) strip for the rapid detection of phenylethanolamine A in urine and pork samples

In this study a one-step immunochromatographic assay based on competitive format was developed for the rapid detection of phenylethanolamine A (PEAA) residues in urine and pork samples. A monoclonal antibody against PEAA was produced from BALB/c mice immunized with the PEAA-BSA conjugate. The results of this qualitative test strip were to be interpreted visually. The visual detection limit (VDL) and threshold level of the optimized immunochromatographic assay for PEAA were 0.1 ng/mL and 0.5 ng/mL, respectively. Cross-reactions with other β-agonists were not significant inhibitions to the performance of the test strip assay. The results from the test strip were in a good agreement with those obtained using a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) assay. The immunochromatographic assay developed here was a useful on-site screening tool that is rapid to use, low in cost, and extremely convenient for the detection of PEAA in urine samples and pork samples.

Geometrical and volume changes of the membranous vestibular labyrinth in guinea pigs with endolymphatic hydrops

OBJECTIVE

To evaluate geometrical and volume changes of membranous vestibular labyrinths in guinea pigs after endolymphatic hydrops (EH).

METHODS

The membranous labyrinths of normal guinea pigs and of those with EH for 4 and 8 weeks were reconstructed after being scanned using micro-computed tomography subseqent to being stained in osmium tetroxide (OsO4). The diameters and volumes of the semicircular ducts, ampullae, utricles and saccules were measured based on the three-dimensional models.

RESULTS

The diameters of the ampullae and utricles of EH guinea pigs were greater than those of the normal guinea pigs, while there were no significant differences in the diameters of the semicircular ducts among all groups. The volumes of ampullae, utricles and saccules of the EH groups were greater than those of the control group, but there were no changes in volumes of semicircular ducts after EH.

CONCLUSION

The dilations of the membranous vestibular labyrinth in guinea pigs with EH mainly occur at the ampullae, utricles and saccules.