Mangiferin activates Nrf2-antioxidant response element signaling without reducing the sensitivity to etoposide of human myeloid leukemia cells in vitro.

AIM: Mangiferin is glucosylxanthone extracted from plants of the Anacardiaceae and Gentianaceae families. The aim of this study was to investigate the effects of mangiferin on Nrf2-antioxidant response element (ARE) signaling and the sensitivity to etoposide of human myeloid leukemia cells in vitro. METHODS: Human HL-60 myeloid leukemia cells and mononuclear human umbilical cord blood cells (MNCs) were examined. Nrf2 protein was detected using immunofluorescence staining and Western blotting. Binding of Nrf2 to ARE was examined with electrophoretic mobility shift assay. The level of NQO1 was assessed with real-time RT-PCR and Western blotting. DCFH-DA was used to evaluate intracellular ROS level. Cell proliferation and apoptosis were analyzed using MTT and flow cytometry, respectively. RESULTS: Mangiferin (50 µmol/L) significantly increased Nrf2 protein accumulation in HL-60 cells, particularly in the nucleus. Mangiferin also enhanced the binding of Nrf2 to an ARE, significantly up-regulated NQO1 expression and reduced intracellular ROS in HL60 cells. Mangiferin alone dose-dependently inhibited the proliferation of HL-60 cells. Mangiferin (50 mol/L) did not attenuate etoposide-induced cytotoxicity in HL-60 cells, and combined treatment of mangiferin with low concentration of etoposide (0.8 µg/mL) even increased the cell inhibition rate. Nor did mangiferin change the rate of etoposide-induced apoptosis in HL-60 cells. In MNCs, mangiferin significantly relieved oxidative stress, but attenuated etoposide-induced cytotoxicity. CONCLUSION: Mangiferin is a novel Nrf2 activator that reduces oxidative stress and protects normal cells without reducing the sensitivity to etoposide of HL-60 leukemia cells in vitro. Mangiferin may be a potential chemotherapy adjuvant.

Triptolide induces cell-cycle arrest and apoptosis of human multiple myeloma cells in vitro via altering expression of histone demethylase LSD1 and JMJD2B.

AIM: To elucidate the relationship between triptolide-induced changes in histone methylation and its antitumor effect on human multiple myeloma (MM) cells in vitro. METHODS: Human multiple myeloma cell line RPMI8226 was used. Apoptosis was evaluated using Annexin-V-FITC/PI-labeled flow cytometry, Hoechst 33258 staining, and transmission electron microscopy. Flow cytometry was used to detect the cell cycle distribution of the apoptotic cells. The presence of the LSD1, JMJD2B, H3K4me2, H3K9me2, and H3K36me2 proteins was verified by Western blot analysis. Semi-quantitative real-time PCR was performed to examine the expression of LSD1 and JMJD2B. RESULTS: Triptolide (10-160 nmol/L) suppressed the proliferation of MM cells in a dose- and time-dependent manner with an IC(50) value of 99.2 ± 9.0 nmol/L at 24 h. Triptolide (50 nmol/L) induced G(0)/G(1) cell cycle arrest in MM cells. The agent (50-150 nmol/L) induced apoptosis of MM cells in a dose-dependent manner. The same concentrations of triptolide suppressed the expression of dimethylated H3K4, dimethylated H3K9 and dimethylated H3K36 by altering the expression of histone demethylase LSD1 and JMJD2B without affecting the expression of histone demethylase LSD1. CONCLUSION: Triptolide potently inhibits the growth of MM cells via regulating the expression of histone demethylase LSD1 and JMJD2B, which lead to abnormal histone methylation.

Comparison of Hantaan and Seoul viral infections among patients with hemorrhagic fever with renal syndrome (HFRS) in Heilongjiang, China.

BACKGROUND: Hemorrhagic fever with renal syndrome (HFRS) is a serious public health problem in China, and is primarily caused by either the Hantaan virus (HTNV) or Seoul virus (SEOV) strains. However, the causative hantavirus has only been definitively identified in a few HFRS cases, and detailed comparisons of patient data for the 2 strains are limited. METHODS: We conducted a 1-y prospective study in Heilongjiang Province, China. A total of 152 patients from 3 hospitals met the HFRS diagnostic criteria used in China. The diagnosis was further confirmed by specific immunoglobulin M to HTNV or SEOV. In addition, serum samples were tested for the presence of HTNV or SEOV using a reverse transcription-polymerase chain reaction (RT-PCR). Clinical manifestations and laboratory findings in patients with the 2 hantaviruses were subsequently compared. RESULTS: Eighty (61.1%) HTNV and 51 (38.9%) SEOV infections were identified. Fever and proteinuria, key to the diagnosis of HFRS, were observed in all patients. The clinical manifestations of hemorrhage and renal injury from SEOV infection were milder than those of HTNV infection. Interestingly, compared to patients with HTNV infection, patients with SEOV presented with a significantly longer febrile period, more normal white blood cell counts or even transient leukocytopenia, a higher incidence of liver injury related to disease severity, and a lower occurrence of the 5 typical phases of HFRS. The mortality was 6.3% in HTNV infections and 0% in SEOV infections. CONCLUSIONS: Clinical manifestations of SEOV infection appear to be milder and less typical than HTNV. This information may help us to improve the diagnosis of SEOV-infected patients.

Effects of triptolide on RIZ1 expression, proliferation, and apoptosis in multiple myeloma U266 cells.

AIM: To investigate the effects of triptolide on proliferation and apoptosis as well as on the expression of RIZ1 in the human multiple myeloma cell line U266 in vitro. METHODS: The effect of triptolide on the growth of U266 cells was studied by MTT assay. Apoptosis was detected by Hoechst 33258 staining and Annexin V/PI double-labeled flow cytometry, and caspase-3 mRNA was measured by RT-PCR. Western blotting, flow cytometry and RT-PCR were used to assess the expression of RIZ1, and the location and expression of H3K9me1 were detected by confocal microscopy and Western blotting. RESULTS: Triptolide significantly inhibited the proliferation of U266 cells in a time- and concentration-dependent manner (the IC(50) value for a 24-h exposure was 157.19+/-0.38 nmol/L). Triptolide induced typical apoptotic morphological changes. Triptolide 40, 80, and 160 nmol/L treatment induced significant caspase-3-dependent apoptosis compared with control group (10.5%+/-1.23%, 37.9%+/-2.45%, and 40.5%+/-2.30% vs 3.8%+/-1.98%, P<0.05). Compared with peripheral blood monocular cells (PBMC) from healthy donors, the protein expression of RIZ1 in U266 cells was relatively low, but the mRNA and protein expression of RIZ1 were strikingly increased by triptolide in a concentration-dependent manner. Triptolide increased the protein expression of RIZ1 and RIZ1 methylates histone H3 lysine 9 in U266 cells. CONCLUSION: Triptolide increased the protein expression of RIZ1, inhibited the proliferation, and induced caspase-dependent apoptosis in U266 cells.

Gambogic acid induces G0/G1 arrest and apoptosis involving inhibition of SRC-3 and inactivation of Akt pathway in K562 leukemia cells.

Gambogic acid (GA), a major active component of gamboge, exhibits potent anticancer activity in many kinds of cancer cells. However, the anticancer mechanism of GA is not clearly understood. Here we showed that GA could cause growth inhibition, induce the G0/G1 phase cell cycle arrest and apoptosis in human chronic myelogenous leukemia cell line K562 cells. Since steroid receptor coactivator-3 (SRC-3), overexpressed in many human malignancies including leukemia, is a central target for cancer therapy, we also explored the effects of GA on SRC-3 and SRC-3-regulated gene products in K562. GA treatment downregulated the expression of SRC-3 and then inhibited the activity of Akt kinase and its downstream targets p70 S6 kinase 1 (S6K1) and glycogen synthase kinase 3beta (GSK3beta) without changes in total protein levels of these three proteins, which thus influenced the expression of the apoptosis related gene Bcl-2 in K562 cells. These results suggest that GA might exhibit its strong antitumor effects via the interruption of SRC-3.

[Effects of gambogic acid on the regulation of steroid receptor coactivator-3 in A549 cells].

OBJECTIVE: To investigate the effects of gambogic acid (GA) on the proliferation inhibition and apoptosis induction in Human lung adenocarcinoma A549 cells in vitro, as well as the regulation of steroid receptor coactivator-3 (SRC-3) to explore the relationship between them. METHODS: The effect of GA on the growth of A549 cells was studied by MTT assay. Apoptosis was detected by Hoechst 33258 staining. The localization of SRC-3 was determined by confocal laser scanning microscopy. Western blot and RT-PCR technique were applied to assess the expression of SRC-3. RESULTS: GA presented a striking proliferation inhibition potency on A549 cells in vitro, as well as apoptosis induction activity in a time- and dose-dependent manner. The IC(50) value for 24 h was (3.17 +/- 0.13) micromol/L. Overexpression of SRC-3 was found in A549 cells, whereas the SRC-3 protein and mRNA expression levels were significantly downregulated in A549 cells induced by GA in a dose-dependent manner. The location of SRC-3 was situated mainly in the cell nuclei. CONCLUSION: GA exhibits a potent proliferation inhibition and apoptosis induction in human lung adenocarcinoma A549 cells, which might correspond to the downregulation of the expression of SRC-3. Thus, it promises to be a new target drug for lung cancer treatment.

Differentiation of hepatocytoid cell induced from whole-bone-marrow method isolated rat myeloid mesenchymal stem cells.

AIM: To explore the expansion and differentiation of hepatocytoid cell induced from myeloid mesenchymal stem cell (MSC) in vitro, in order to find suitable resource of hepatocytes for bioartificial liver or liver transplantation. METHODS: The rat myeloid MSC was isolated and divided into three groups which were cultured by Friedensteion method, and then were induced by culture fluid, culture fluid plus cholestatic serum and culture fluid plus hepatocyte growth factor (HGF), respectively. Hepatocytoid cell as well as expression of CK18 and AFP was observed by immunohistochemistry. RESULTS: After the induction for 21 d, hepatocytoid cell was observed, and its expression of CK18 and AFP was detected by immunohistochemistry in MSC cultured with cholestatic serum. Furthermore, on the 35th d, albumin mRNA was expressed in the cell, suggesting the inducing effect was similar to that by HGF. CONCLUSION: Rat myeloid MSC can differentiate into hepatocyte lineage under appropriate condition. This method is easy to operate.

[Expression of hepatic Bcl-2 and Bax proteins in schistosome-infected mice and the role of pentoxifylline].

OBJECTIVE: To study the expression of hepatic Bcl-2 and Bax proteins in mice infected with Schistosoma japonicum and the role of pentoxifylline (PTX) in the expression. METHODS: Forty mice were randomly divided into 4 groups: one normal control group,mice in the other three groups were all infected each with 25 cercariae, the infected control group was fed for 10 weeks after infection, and 2 weeks after infection, the high dose PTX group was given PTX 360 mg/(kg x d) for 8 weeks and the low dose PTX group was given PTX 180 mg/(kg x d)also for 8 weeks. At the end of 10 weeks all the mice were killed. Bcl-2 and Bax proteins expression was detected by immunohistochemisty. RESULTS: Compared with the normal control group, the expression of Bcl-2 and Bax was significantly higher in the infected control group (P < 0.05). Bcl-2 was significantly higher in high (dose PTX group than in the infected control group and in low dose PTX group (P < 0.05). However there was no significant difference in the expression of Bax among the groups (P > 0.05). CONCLUSION: PTX treatment can significantly increase the expression of Bcl-2 in liver tissue of schistosome-infected mice in a dose-dependent manner, and may play a role against liver inflammation and schistosomiasis-related liver fibrosis.

[Experimental study on enzyme dot assay for detection of hemorrhagic fever with renal syndrome antigen].

OBJECTIVE: To establish a new and efficient method(IEDA) for detection of hemorrhagic fever with renal syndrome virus (HFRSV) antigen. METHODS: An immune enzyme dot assay (IEDA) with mixture of three sorts anti-HFRSV-IgG, which was obtained from rabbit vaccinated with EHFV R22, Chen and Hubei strain was employed to detect HFRSV antigen in serum and urine from epidemic hemorrhagic fever (EHF) patients, and compared with indirect immune fluorescence assay (I-IFA), 76 serum samples and 40 urine samples were detected in this study. RESULTS: The results showed that the total positive rate of HFRSV antigen detected by IEDA was 73.68% in serum and 65.00% in urine, while that detected by I-IFA was 75.00% and 70.00%, respectively. The positive rate in primary phase (within 5 days) of HFRSV antigen detected by IEDA was 94.34% in serum and 83.33% in urine, while that detected by I-IFA was 64.42% and 55.56%, respectively, there was significant difference in both serum and urine detections. Correlation study showed a high correlation in the result of IEDA and I-IFA. CONCLUSION: The results of this study suggested that the IEDA, as compared with I-IFA, was a more specific, sensitive, rapid and simple method with higher positive rate in primary phase. IEDA could be widely used for early diagnosis of HFRS in hospital at grassroots level.

Effects of autoantibodies against beta(1)-adrenoceptor in hepatitis virus myocarditis on action potential and L-type Ca(2+) currents.

AIM: To investigate the effects of autoantibodies against beta(1)-adrenoceptor in hepatitis virus myocarditis on action potential and L-type Ca(2+) currents. METHODS: Fifteen samples of autoantibodies against beta(1)-adrenoceptor positive sera of patients with hepatitis virus myocarditis were obtained and IgGs were purified by octanoic acid extraction. Binding of autoantibodies against beta(1)-adrenoceptor to guinea pig cardiac myocytes was examined by immunofluorescence. Using the patch clamp technique, the effects on the action potential and I(Ca-L) of guinea pig cardiac myocytes caused by autoantibodies against beta(1)-adrenoceptor in the absence and presence of metoprolol were investigated. Cell toxicity was examined by observing cell morphology and permeability of cardiac myocytes to trypan blue. RESULTS: The specific binding of autoantibodies against beta(1)-adrenoceptor to guinea pig cardiomyocytes was observed. Autoantibodies against beta(1)-adrenoceptor diluted at 1:80 prolonged APD(20), APD(50) and APD(90) by 39.2%, 29.1% and 15.2% respectively, and only by 7.2%, 5.3% and 4.1% correspondingly in the presence of 1 micromol/L metoprolol. Autoantibodies against beta(1)-adrenoceptor diluted at 1:80, 1:100 and 1:120 significantly increased the I(Ca-L) peak current amplitude at 0 mV by 55.87+/-4.39%, 46.33+/-5.01% and 29.29+/-4.97% in a concentration-dependent manner. In contrast, after blocking of beta(1)-adrenoceptors (1 micromol/L metoprolol), autoantibodies against beta(1)-adrenoceptor diluted at 1:80 induced a slight increase of I(Ca-L) peak amplitude only by 6.81+/-1.61%. A large number of cardiac myocytes exposed to high concentrations of autoantibodies against beta(1)-adrenoceptor (1:80 and 1:100) were turned into rounded cells highly permeable to trypan blue. CONCLUSION: Autoantibodies against beta(1)-adrenoceptor may result in arrhythmias and/or impairment of myocardiums in HVM, which would be mediated by the enhancement of I(Ca-L).

[Expression of IL-2 and TNF-alpha in the liver and the effect of injection of these cytokines on liver fibrosis in mice infected with Schistosoma japonicum].

OBJECTIVE: To detect the expression of IL-2 and TNF-alpha in the liver at different period postinfection of Schistosoma japonicum and their effect on liver fibrosis after supplementary injection of these cytokines. METHODS: Mice were infected with schistosome cercariae and divided into 3 groups. Two groups were injected (i.p.) every other day with IL-2 and TNF-alpha respectively for consecutive 4 wk. The third group and an uninfected group of normal mice were regarded as control. The ABC immunohistochemistry and pathologic image multimedia quantification system were applied to detect activity of IL-2 and TNF-alpha. RESULTS: The level of IL-2 and TNF-alpha in the liver in infected but untreated group slowly decreased (from 8, 11, 14 to 18 wk). The supplementary injection of the cytokines at 6 wk postinfection in the two groups increased the cytokines significantly, the level of IL-2 or TNF-alpha was higher at 1-8 wk after the last injection than that of both infected and uninfected control groups (P < 0.01). The granulomatous inflammation and fibrosis in the livers of the two groups were slighter than that of the control. CONCLUSION: At the 6th wk postinfection with egg deposition, exogenous supplementation with TNF-alpha or IL-2 induces enhanced expression of the two kinds of cytokines, corresponding to a diminished degree of the liver granulomatous inflammation and fibrosis.