Involvement of the Mitochondrion-dependent and the Endoplasmic Reticulum Stress-signaling Pathways in Isoliquiritigenin-induced Apoptosis of HeLa Cell

Objective Isoliquiritigenin （ISL）, a licorice chalconoid, is considered to be a bioactive agent with chemopreventive potential. This study investigates the mechanisms involved in ISL-induced apoptosis in human cervical carcinoma HeLa cells. Methods Cell viability was evaluated using a 3-（4, 5-dimethylthiazol-2-yl）-2, 5-diphenyl-tetrazolium bromide （MTT） assay. Apoptosis was determined by flow cytometry using an Annexin V-FITC Apoptosis Detection Kit. The intracetlular ROS levels were assessed using a 2, 7-dichlorofluorescein probe assay. The mitochondrial membrane potential was measured with the dual-emission potential-sensitive probe 5, 5＇, 6, 6＇-tetra-chloro-1, 1＇, 3, 3＇-tetraethyl-imidacarbocyanine iodide （JC-1）. The degradation of poly-ADP-ribose polymerase （PARP） protein, the phosphorylation of PKR-like ER kinase （PERK）, the phosphorylation of the a-subunit of eukaryotic initiation factor 2 （elF2a）, the expression of the 78 kD glucose-regulated protein （GRP 78）, and the activation of caspase-12 were analyzed via western blot analysis. Results ISL significantly inhibited the proliferation, the increase in ROS levels and apoptotic rates of HeLa cells in a concentration-dependent manner. Moreover, ISL induced mitochondrial dysfunction, caspase activation, and PARP cleavage, which displayed features of mitochondria dependent on apoptotic signals. Besides, exposure of HeLa cells to ISL triggered endoplasmic reticulum （ER） stress, as indicated by the increase in p-elF2a and GRP78 expression, ER stress-dependent apoptosis is caused by the activation of ER-specific caspase-12. Conclusion The findings from our study suggest that ISL-induced oxidative stress causes HeLa cel apoptosis via the mitochondrion-dependent and the ER stress-triggered signaling pathways.

Mechanism of Ascorbic Acid-induced Reversion Against Malignant Phenotype in Human Gastric Cancer Cells

Objective To find out the mechanisms of redifferentiation and reversion of malignant human gastric cancer cells induced by ascorbic acid. Methods Human gastric cancer cells grown in the laboratory were used. The Trypan blue dye exclusion method was used to determine the cell doubling time. The electrophoresis rate and colonogenic potential were the indices used to measure the rate of redifferentiation. The content of malondialdehyde （MDA） was measured using the thiobarbituric acid （TBA） method. The activities of superoxide dismutase （SOD）, catalase （CAT） and the content of H2O2 were evaluated by spectrophotography. Results Six mmol/L ascorbic acid was used as a positive control. Human gastric cancer cells were treated with 75 μm hydrogen peroxide, which alleviated many of the malignant characteristics. For example, the cell surface charge obviously decreased and the electrophoresis rate dropped from 2.21 to 1.10 pm·s^-1·cm^-1 The colonogenic potential, a measure of cell differentiation, decreased 90.2%. After treatment with ascorbic acid, there was a concentration- and time-dependent increase in hydrogen peroxide （H2O2） and the activity of superoxide dismutase （SOD）. However, the activity of catalase （CAT） resulted in a concentration- and time-dependent decrease. SOD and 3-amino- 1,2,4-triazole （AT） exhibited some effects, but there were statistically significant differences between the SOD and AT group and the H2O2 group, Conclusions Ascurbic acid induces growth inhibition and redifferentiation of human gastric cancer cells through the production of hydrogen peroxide.

Bromination of N-phenyloxypropyl-N'-ethyl-4,4'-bipyridium in cucurbit[8]uril molecular reactor

CB[n]（n= 6-8） is a family of synthetic macrocyclic host molecules composed of n glycoluril units,which can be employed as molecular reactor.N-Phenyloxypropyl-N＇-ethyl-4,4＇-bipyridium（1） was designed to form a host-guest inclusion complex with CB[n]（n = 6-8）,subsequently,the bromination reaction of 1 and its corresponding inclusion complexes was investigated in this work.In the case of 1/CB[8],the folded including mode is quite helpful to acquire 1-bormination product completely through intramolecular charge transfer（ICT）,and CB[8]can provide a safe bromination environment for 1.