Qiong Liu

A polysaccharide-protein complex from Lycium barbarum upregulates cytokine expression in human peripheral blood mononuclear cells

The production of cytokine is a key event in the initiation and regulation of an immune response. Many compounds are now used routinely to modulate cytokine production, and therefore the immune response, in a wide range of diseases, such as cancer. Interleukin-2 and tumor necrosis factor-alpha are two important cytokines in antitumor immunity. In this study, the effects of Lycium barbarum polysaccharide-protein complex (LBP(3p)) on the expression of interleukin-2 and tumor necrosis factor-alpha in human peripheral blood mononuclear cells were investigated by reverse transcription polymerase chain reaction (RT-PCR) and bioassay. Administration of LBP(3p) increased the expression of interleukin-2 and tumor necrosis factor-alpha at both mRNA and protein levels in a dose-dependent manner. The results suggest that LBP(3p) may induce immune responses and possess potential therapeutic efficacy in cancer.

Effects of selenium overexposure on glutathione peroxidase and thioredoxin reductase gene expressions and activities

Selenium (Se) is an essential trace element in animals and human, however, excess Se intake can result in adverse health effects. Se supplementation increased glutathione peroxidase (GSH-Px) and thioredoxin reductase (TR) expressions in Se-deficient rats. However, little information is available on the relationship between Se overexposure on GSH-Px and TR mRNA levels and activities. In this study, the effects of Se overexposure on GSH-Px and TR mRNA levels and activities were investigated by reverse transcription-polymerase chain reaction (RT-PCR) and activity assay. Experimental groups of male Wistar rats were injected intraperitoneally (ip) with sodium selenite at doses of 20, 40, and 80 µg Se/kg/d for 15 d, respectively. Se levels were elevated dose-dependently in rat liver, kidney, and testis tissues. GSH-Px mRNA levels and activities in the liver and testis for rats injected with 20 µg Se/kg/d were increased significantly as compared with those in the control group. However, intraperitoneal injection of 40 and 80 µg Se/kg/d dramatically decreased GSH-Px mRNA expression and activity in liver and testis. The changes of TR mRNA level and activity in the liver and kidney were similar to those of GSH-Px in the liver and testis when supplemented with 40 and 80 µg Se/kg/d. There were no significant effects of Se status on kidney GSH-Px and testis TR expressions. The results suggested that Se overexposure had an adverse effect on GSH-Px and TR mRNA levels and activities, and there could be tissue differences in the regulation of selenoprotein levels.

Inhibitory effects of thioredoxin reductase antisense RNA on the growth of human hepatocellular carcinoma cells

Thioredoxin reductase (TrxR) in conjunction with thioredoxin (Trx) is a ubiquitous intracellular oxidoreductase system with antioxidant and redox regulatory roles. In some human tumors, the thioredoxin system is found overexpressed. We have used an antisense approach to investigate whether inhibition of TrxR overexpression can suppress the growth of human hepatocellular carcinoma SMMC‐7721 cells. TrxR cDNA fragment was inserted in the antisense direction into pcDNA3.1/myc‐His and SMMC‐7721 cells were stably transfected with the plasmid construct. The results showed that TrxR antisense RNA could significantly reduce TrxR mRNA level and activity, and suppress the growth of SMMC‐7721 cells. Cell‐cycle analysis showed G2/M phase arrest in SMMC‐7721 cells transfected with TrxR antisense plasmid. TrxR antisense RNA could significantly increase p53 mRNA level and decrease Bcl‐2 mRNA level by reverse transcriptase‐polymerase chain reaction (RT‐PCR). Furthermore a significant decrease in human telomerase reverse transcriptase (hTERT) mRNA level was found in SMMC‐7721 cells transfected with TrxR antisense plasmid. Flow cytometry and telomere fluorescence in situ hybridization (Flow FISH) showed that TrxR antisense RNA could significantly reduce the telomere fluorescence in SMMC‐7721 cells. The results suggested that TrxR antisene RNA inhibited the growth of SMMC‐7721 cells through an accumulation of cell cycle at G2/M phase, an increase in p53 mRNA level and a reduction in telomere fluorescence and Bcl‐2, hTERT mRNA levels.

Effects of trace elements on the telomere lengths of hepatocytes L-02 and hepatoma cells SMMC-7721.

The effects of selenium, zinc, iron, chromium, and lead on telomere lengths of human cells have not been investigated. This article adopted flow cytometry and fluorescence in situ hybridization to investigate the impact of different elements on cellular apoptosis and telomere lengths of human hepatocytes L-02 and hepatoma cells SMMC-7721. Results showed that these trace elements under the following dosages did not have remarkable effect on cellular apoptosis. However, sodium selenite at doses of 0.5 and 2.5 μmol/L significantly extended the telomere length of hepatocytes L-02; 0.5 μmol/L lead acetate remarkably shortened the telomere length of L-02 cells; 80 μmol/L zinc sulfate, 20 μmol/L ferric chloride, and 200 μmol/L chromic chloride only had slight impact on the telomere length, respectively. Regarding hepatoma cells SMMC-7721, sodium seleite at 0.5 and 2.5 μmol/L had little impact on the telomere length; 80 μmol/L zinc sulfate significantly accelerated the loss of telomere length, whereas 20 μmol/L ferric chloride, 200 μmol/L chromic chloride, and 0.5 μmol/L lead acetate remarkably extended the telomere lengths, respectively. The results revealed differential effects of each trace element on the life-span of human hepatocytes and hepatoma cell lines, which suggested further research on somatic hepatocytes and hepatoma in vivo.

The mechanism for the effect of selenium supplementation on immunity

Lipid peroxide (LPO) in lymphocytes from mice was evaluated by measuring substances reactive to thiobarbituric acid (TBA). The product resulting from the reaction of TBA with lymphocytes was extracted with n-butyl and fluorescence intensity was determined. The degree of lipid peroxidation, expressed as fluorescence intensity f547, was assessed for stimulation of lymphocytes with concanavalin A (Con A), and was related to lymphocyte proliferation in response to Con A if Se was administered. The lymphocyte proliferation was determined by [3H]thymidine incorporation, expressed as cpm. The effect of superoxide dismutase (SOD), added to cell culture on lymphocyte proliferation was also evaluated. It was found that LPO in lymphocytes before Con A stimulation was significantly less than that after stimulation (p<0.001), and that SOD promoted lymphocyte proliferation dose dependently. The addition of Na2SeO3 to lymphocyte culture or supplementation in drinking water to mice decreased the produced LPO in lymphocyte in response to Con A. In the presence of Se, there is an inverse correlation between the levels of LPO in lymphocyte and the stimulated proliferation (r=−0.8902,r=−0.9439). In conclusion, active oxygen species scavenging was proposed as one of the mechanisms for Se to promote immunity.

Antagonistic effect of scutellarin on the toxicity of selenium in rat livers.

Selenium has both nutritional function and toxicity according to its concentration and species. To counteract the toxicity of selenium, scutellarin was investigated. Wistar rats were supplemented with 40 µg Se/kg/d as sodium selenite, 40 µg Se/kg/d with 20 mg/kg/d scutellarin, and 20 mg/kg/d scutellarin, respectively, for 15 d. The mRNA levels and activities of glutathione peroxidase (GSH-Px) and thioredoxin reductase (TR), and the malondialdehyde (MDA) contents were measured. Reactive oxygen species (ROS) were detected by chemiluminescence assay, and tissue conformation was investigated by histological study. The results showed significant decreases of mRNA levels and activities of GSH-Px and TR and a significant increase of MDA content in livers of the Se-treated rats (p<0.05, compared with the control). Supplementation of scutellarin to the Se-treated group significantly inhibited the decreases of mRNA levels and activities, and the increase of MDA content (p<0.05, compared with the Setreated group). Meanwhile, scutellarin-scavenged ROS generated in the mixture of sodium selenite, reduced glutathione, and oxygen. Liver injury was displayed in slices exposed to selenium at the present dose. The groups treated with both selenium and scutellarin or only scutellarin did not show significant tissue damage. Thus, scutellarin had an antagonistic effect against the toxicity of selenium.

Effect of selenium in recovery of immunity damaged by H2O2 and 60Co radiation.

Con A stimulated lymphocytes proliferation was measured as [3H]thymidine incorporation and IgG was quantified by single radial immunodiffusion to study recovering or protecting effect of selenium (Se) on immunity attacked by exogenous active oxygen species, H2O2 and60Co-radiation, respectively. Lipid peroxidation was also determined to observe the relation between antioxidation ability and protecting ability of Se. It was found that H2O2 injured lymphocytes immunocompetence deeply and60Co-radiation decreased immune response capacity greatly, but that administration of Se counteracts this damage. The antioxidative ability of Se was correlated with its protecting ability.

Detection of DNA with Catalytic Beacons Based on Peroxidase-oxidase Oscillating Reaction

This paper aims at investigating a new method for the detection of DNA with catalytic beacons based on peroxidase-oxidase (PO) oscillation and analytic pulse perturbation technique. Two DNAzymes were constructed by the binding of specific DNA sequence with hemin or by the hybridization of target DNA with the catalytic beacon. Both DNAzymes possessed peroxidase-like activity and perturb the PO oscillator reaction when they were added into the oscillation system. The period and amplitude of oscillation increased significantly by both DNAzymes, which implied the decrease in the average rate of consumption of oxygen in solution, i.e., the decrease of the average rate of NADH oxidation. The results provide a new sensitive method for DNA detection and molecular recognition

Identification of a New Protein from Silkworm Pupas by Biological Mass Spectrometry

To find out the efficient peptide of selenium-rich silkworm pupas in inducing the apoptosis of hepatoma cells, selenium-containing proteins were isolated and characterized. One of the two major proteins in selenium-rich silkworm pupas was identified to be a new protein by peptide mass fingerprinting on matrix assisted laser desorption ionization - time of flight - mass spectrometry. Amino acid sequences of peptides digested by trypsin from the new protein were determined by capillary liquid chromatography electrospray ionization - quadrupole/time of flight - mass spectrometry and searched with Mascot in NCBI database. Results showed that the six major peptides from the protein were also new peptides that could not be found in the database up to date

Quantum Resonance Spectrometer Dynamically Monitored Sacroma-180 Tumor Growth in Mice

Quantum resonance spectrometer (QRS) was used to dynamically measure quantum effect values (QE values) of immunity, anticancer capacity, cancer cell, and malignant grower in mice inoculated with Sacroma-180 (S-180). Results showed that QE values of immunity and anticancer capacity in S-180 mice were significantly lower than that in healthy mice (p<0.001). Meanwhile, QE values of cancer cells and malignant grower in S-180 mice decreased time-dependently, reached the minimum at the 7thday and returned normal afterwards. In contrast, those two values in healthy mice remained constant during the whole experiments. The results suggested that QRS is a sensitive and scatheless instrument for predicting forepart tumor, but its incapability in identifying anaphase tumor of S-180 in mice remains to be solved.