Guohui Cui

Curcumin, a potent anti-tumor reagent, is a novel histone deacetylase inhibitor regulating B-NHL cell line Raji proliferation.

AbstractAim:To investigate curcumin (diferuloylmethane) induced apoptosis and its molecular mechanism of action in B-NHL cell line Raji cells.Methods:Raji cells were cultured in RPMI-1640 medium and treated with curcumin in different concentrations. 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay was used to detect growth inhibition and Hoechst 33258 staining was used to detect apoptosis. Immunocytochemistry and Western blot were used to detect the expressions of histone deacetylase 1, 3, and 8 (HDAC1, HDAC3, and HDAC8) and acetylated histone H4 (Ac-histone H4) protein.Results:Curcumin inhibited the proliferation of B-NHL cell line Raji cells with a 36-h IC50 value of 24.1±2.0 μmol/L. Hoechst 33258 staining showed that curcumin could induce Raji cell apoptosis. The expression levels of HDAC1, HDAC3, and HDAC8 proteins were downregulated following curcumin treatment in Raji cells, whereas Ac-histone H4 protein expression was upregulated after treatment with curcumin.Conclusion:Curcumin, as a new member of the histone deacetylase inhibitors, can inhibit the expression of class I HDACs (HDAC1, HDAC3, and HDAC8), and can increase the expression of Ac-histone H4 in Raji cells. Curcumin plays an important role in regulating B-NHL cell line Raji cell proliferation and apoptosis.

Inhibitory effect of triptolide on lymph node metastasis in patients with non-Hodgkin lymphoma by regulating SDF-1/CXCR4 axis in vitro.

AbstractAim:To investigate the antiproliferative effect of triptolide on B-NHL cell line Raji cells, to study its effect on lymph node metastasis in patients with non-Hodgkins lymphoma (NHL) in vitro, and to explore the underlying mechanism regulating SDF-1/CXCR4 axis.Methods:The effects of triptolide on the growth of Raji cells were studied by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay. The effects of triptolide on SDF-1 mRNA expression in lymph node stromal cells from patients with NHL were determined by reverse transcriptase-polymerase chain reaction (RT-PCR). The effects of triptolide on CXCR4 expression on lymphoma cells freshly isolated from the lymph nodes of these patients were studied by flow cytometric analysis. Chemotaxis assays were performed to observe the effects of triptolide on migration of primary lymphoma cells towards recombinant human SDF-1α (rhSDF-1α) or cultured lymph node stromal cells in vitro.Results:Triptolide inhibited the proliferation of B-NHL cell line Raji cells in a dose- and time-dependent manner with a 24-h IC50 value of 43.06 nmol/L and a 36-h IC50 value of 25.08 nmol/L. The expression of SDF-1α mRNA in lymph node stromal cells obtained from patients with NHL was decreased after treatment by triptolide at concentrations of 25 and 50 nmol/L for 24 h. Flow cytometry analysis showed that the CXCR4 expression on primary lymphoma cells were downregulated gradually in a dose-dependent manner following triptolide treatment. Chemotaxis assays revealed that the migration of freshly isolated lymphoma cells towards either rhSDF-1 or cultured lymph node stromal cells was markedly inhibited by the addition of triptolide in vitro, and the inhibition was dose-dependent.Conclusion:Triptolide can inhibit the proliferation of B-NHL cell line Raji cells. Moreover, triptolide is able to inhibit the migration of lymphoma cells via lymph nodes in vitro. The potential antitumor mechanisms of triptolide are related to the antiproliferative effect and the blockage of SDF-1/CXCR4 axis.

Involvement of Regulations of Nucleophosmin and Nucleoporins in Gambogic Acid-Induced Apoptosis in Jurkat Cells

Gambogic acid, the main active compound of gamboge resin of Garcinia hanburryi, has recently exhibited marked antitumour potency on solid tumours of various derivations. We demonstrate here that gambogic acid also present powerful antileukaemic potency through both growth arrest and apoptosis induction in Jurkat cells, which was accompanied by typical apoptotic morphological changes and sharp decreased expression of Bcl-xL and Bcl-2. Furthermore, nucleophosmin, recently demonstrated to be mutated and aberrantly localized in the cytoplasm of leukaemia blasts in a high proportion of patients with acute myeloid leukaemia, was over-expressed in Jurkat cells. As the sole site of nucleocytoplasmic communication, the protein components of nuclear pore complex, such as NUP98, NUP88, NUP214 complex, were also deregulated in Jurkat cells. Especially, NUP98 was found to distribute mainly at the cell membrane, while NUP88 and NUP214 situated not just at the nuclear envelope, but also in the cytoplasm. However, in vitro treatment with gambogic acid resulted in significantly reduced expression of nucleophosmin and all three nucleoporins in a dose-dependent manner. Moreover, most of NUP88 and NUP214 nucleoporins were relocated to the nuclear rim in the gambogic acid-treated cells. These results suggest that the fact that nucleophosmin and some nucleoporins might act as new targets of gambogic acid, correlates well with the sensitivity to gambogic acid, as well as the rate of apoptosis induced by gambogic acid. Mechanisms that regulate nucleocytoplasmic transport of proteins may provide novel opportunities for drug development.

Betulinic acid inhibits autophagic flux and induces apoptosis in human multiple myeloma cells in vitro

Aim:To investigate the effects of betulinic acid (BA) on apoptosis and autophagic flux in multiple myeloma cells and the relationship between the two processes.Methods:The proliferation of human multiple myeloma KM3 cells was measured with MTT assay. FITC/PI double-labeled flow cytometry (FCM) and Hoechst 33258 staining were used to analyze the cell apoptosis. Caspase 3, PARP, Beclin1, LC3-II, and P62 were detected using Western blotting.Results:Treatment of KM3 cells with BA (5−25 μg/mL) suppressed the cell proliferation in time- and dose-dependent manners. The IC50 values at 12, 24, and 36 h were 22.29, 17.36, and 13.06 μg/mL, respectively. BA treatment dose-dependently induced apoptosis of KM3 cells, which was associated with the activation of caspase 3. However, Z-DEVD-FMK, a specific inhibitor of caspase 3, did not decrease, but rather sensitized the cells to BA-induced apoptosis, suggesting an alternative mechanism involved. On other hand, BA treatment dose-dependently increased the accumulation of LC3-II and P62 in KM3 cells, representing the inhibition of autophagic flux. Furthermore, BA treatment dose-dependently downregulated the expression of Beclin 1, an important inducer of autophagy, in KM3 cells. In the presence of BA, Z-DEVD-FMK induced autophagy and increased the amount of LC3-II in KM3 cells, which may occur via attenuating BA-induced decrease in the level of Beclin 1. Similarly, rapamycin, an autophagy inducer, increased the amount of LC3-II in KM3 cells. In the presence of BA, rapamycin caused further increase in the amount of LC3-II. Furthermore, rapamycin sensitized BA-treated KM3 cells to apoptosis.Conclusion:The results demonstrate that BA induces apoptosis and blocks autophagic flux in KM3 cells. Furthermore, in addition to activation of caspase 3, the inhibition of autophagic flux also contributes to the BA-mediated apoptosis of KM3 cells.

Regulating expressions of cyclin D1, pRb, and anti-cancer effects of deguelin on human Burkitt's lymphoma Daudi cells in vitro

AbstractAim:To investigate anticancer effects and molecular mechanism of deguelin on human Burkitts lymphoma Daudi cells in vitro and compare the cytotoxicities of deguelin on Daudi cells and human peripheral blood monocular cells (PBMC).Methods:The effects of deguelin on the growth of Daudi cells were studied by 3-(4, 5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay. Apoptosis were dectected through Hoechst 33258 staining and Annexin V/PI double-labeled cytometry. The effect of deguelin on the cell cycle of Daudi cells were studied by a propidium iodide method. The expressions of cyclin D1 and pRb were checked by Western blot.Results:The proliferation of Daudi cells were decreased in deguelin-treated group with a 24-h IC50 value of 51.55 nmol/L. Deguelin induced Daudi cells apoptosis was in a time- and dose-dependent manner. G0/G1 phase increased and S phase decreased in Daudi cells treated with deguelin. With deguelin 0, 5, 10, 20, and 40 nmol/L treatment for 24 h, G0/G1 phase increased from 37.34% to 56.56%, whereas S phase decreased from 37.72% to 21.36%. PBMC was less sensitive to the cytotoxic effect of deguelin than Daudi cells. The expression of cyclin D1 and pRb protein were decreased sharply in Daudi cells treated with deguelin.Conclusion:Deguelin is able to inhibit the proliferation of Daudi cells by regulating the cell cycle that arrested cells at G0/G1 phase and inducing the cell apoptosis. Moreover, deguelin selectively induced apoptosis of Daudi cells with low toxicity in PBMC. The antitumor effects of deguelin were related to down-regulating the expression of cyclin D1 and pRb protein.

Oridonin induces NPM mutant protein translocation and apoptosis in NPM1c+ acute myeloid leukemia cells in vitro

Aim:Skewed cytoplasmic accumulation of NPM mutant protein (NPM1c+) is close related to leukemia pathogenesis. The aim of this study was to investigate whether oridonin, a diterpenoid isolated from the Chinese traditional medicine Rabdosia rubescens, was able to interfere with NPM1c+ protein trafficking and induce apoptosis in NPM1c+ acute myeloid leukemia cells in vitro.Methods:OCI-AML3 cell line harboring a NPM1 gene mutation was examined. Cell growth was detected by MTT assay. Cell apoptosis was evaluated using flow cytometry and Hoechst 33258 staining. The expression and subcellular localization of relevant proteins were detected by Western blot and immunofluorescent staining. The mRNA expression was detected by RT-PCR.Results:Oridonin (2–12 μmol/L) dose-dependently inhibited the viability of OCI-AML3 cells (the IC50 value was 3.27±0.23 μmol/L at 24 h). Moreover, oridonin induced OCI-AML3 cell apoptosis accompanied by activation of caspase-3 and nuclear translocation of NPM1c+ protein. Oridonin did not change the expression of Crm1 (the export receptor for nuclear export signal-containing proteins), but induced nuclear translocation of Crm1. Oridonin markedly increased the expression of nucleoporin98 (Nup98), which had an important role in Crm1-mediated nuclear protein export, and induced nuclear accumulation of Nup98. Furthermore, oridonin markedly increased the expression of p14arf and p53.Conclusion:In NPM1c+ leukemia cells, oridonin induces NPM1c+ protein translocation into the nucleus possibly via nuclear accumulation of Crm1; the compound markedly increases p53 and p14arf expression, which may contribute to cell apoptosis.

Deguelin inhibits expression of IκBα protein in Raji and U937 cells

AbstractAim:To determine whether deguelin can regulate the expression of nuclear factor kappa B (NF-κB) binding protein (IκBα) in U937 human leukemia cells and Raji human B lymphoma cells.Methods:The localization of IκBα protein was investigated by using an immunofluorescence method. The expression of IκBα and NF-κB/p65 proteins in Raji and U937 cells were investigated by using Western blotting. Apoptosis was detected through annexin V/PI double-labeled cytometry.Results:IκBα localized in the cytoplasm in untreated and deguelin-treated cells. After treatment with tumor necrosis factor α (TNF-α) or deguelin plus TNF-α for 15 min, there was a substantial reduction in the amount of IκBα protein. The expression of IκBα was downregulated by deguelin in Raji and U937 cells. Deguelin induced apoptosis in U937 cells.Conclusion:Deguelin inhibited the expression of IκBα protein in U937 and Raji cells. The anti-proliferative activity of deguelin is related to the signal pathway of NF-κB.

Deguelin regulates nuclear pore complex proteins Nup98 and Nup88 in U937 cells in vitro

AbstractAim:To investigate the anticancer effects and the molecular mechanisms of deguelin on human U937 leukemia cells, and to explore the underlying mechanism regulating nucleoporin 98 (Nup98) and nucleoporin 88 (Nup88) in vitro.Methods:The effects of deguelin on the growth of U937 cells were studied by MTT assay. The effect of deguelin on the cell cycle of U937 cells was studied by using a propidium iodide method. The localization of the nuclear pore complex proteins Nup98 and Nup88 was investigated by using immunofluorescence and immunoelectron microscopy. The expression of Nup98 and Nup88 in U937 cells was investigated by using flow cytometry and Western blot.Results:The proliferation of U937 cells was inhibited in the deguelin-treated group, with a 24-h IC50 value of 21.61 nmol/L and a 36-h IC50 value of 17.07 nmol/L. U937 cells treated with deguelin had reduced percentages of cells in the G0/G1 phase, whereas cells accumulated in the S and G2/M phases. Nup88 and Nup98 were found on both the nuclear and cytoplasmic sides of the U937 cells by using immunofluorescence and immunoelectron microscopy. The expression of Nup98 was upregulated and that of the Nup88 protein was downregulated in U937 cells treated with deguelin.Conclusion:Deguelin is able to inhibit the proliferation of U937 cells by regulating the cell cycle such that cells are arrested at the S and G2/M phases, so that the proportion of cells in the G0/G1 phase decreases. The antitumor effects of deguelin are related to upregulating the expression of Nup98 and downregulating the expression of Nup88 protein in U937 cells.

Deguelin, a selective silencer of the NPM1 mutant, potentiates apoptosis and induces differentiation in AML cells carrying the NPM1 mutation.

Nucleophosmin (NPM1) is a multifunctional protein that functions as a molecular chaperone, shuttling between the nucleolus and the cytoplasm. In up to one third of patients with acute myeloid leukemia, mutation of NPM1 results in the aberrant cytoplasmic accumulation of mutant protein and is thought to be responsible for leukemogenesis. Deguelin, a rotenoid isolated from several plant species, has been shown to be a strong anti-tumor agent. Human leukemia cell lines were used for in vitro studies. Drug efficacy was evaluated by apoptosis and differentiation assays, and associated molecular events were assessed by Western blot. Gene silencing was performed using small interfering RNA (siRNA). Deguelin exhibited strong cytotoxic activity in the cell line of OCI-AML3 and selectively down-regulated the NPM1 mutant protein, which was accompanied by up-regulation of the activity of caspase-6 and caspase-8 in high concentrations. Deguelin induced differentiation of OCI-AML3 cells at a nontoxic concentration which was associated with a decrease in expression of activated caspase-8, p53, p21, and the 30-kD form of CCAAT/enhancer binding protein α (C/EBPα), whereas no effects were found in OCIM2 cells expressing NPM-wt. Moreover, treatment with siRNA in the NPM mutant cell line OCI-AML3 decreased expression of p53, p21, pro-caspase-8, and the 30-kD form of C/EBPα, and it inhibited proliferation and induced differentiation of the OCI-AML3 cells. In conclusion, deguelin is a potent in vitro inhibitor of the mutant form of NPM1, which provides the molecular basis for its anti-leukemia activities in NPM1 mutant acute myeloid leukemia cells.

Effect of Gambogic acid on the regulation of hERG channel in K562 cells in vitro.

Overexpression of human ether-à-go-go (eag) related gene (hERG) has been found in a broad range of human leukemia cell lines and primary human leukemia. The block of hERG protein might be a potential therapeutic strategy for leukemia. Gambogic acid (GA) has recently exhibited marked anti-tumor potency on solid tumors of various derivations. Here, we investigated the anti-leukemia effects of GA and its relation to the regulation of hERG in K562 leukemia cells in vitro. K562 cells were treated with various concentrations of GA (0.125–8.0 µmol/L) for 0–72 h. MTT assay was used to evaluate the inhibition effect of GA on the growth of K562 cells. Cell apoptosis was measured through both Annexin-V FITC/PI double-labeled cytometry and transmission electron microscopy. Cell cycle regulation was studied by a propidium iodide method. RT-PCR and Western blot were applied to detect the expression level of hERG in K562 cells. GA presented striking growth inhibition and apoptosis induction potency on K562 cells in vitro in a time- and dose-dependent manner. The IC50 value of GA for 24 h was 2.637±0.208 µmol/L. Moreover, GA induced K562 cells arrested in G0/G1 phase, accordingly, cells in S phase decreased gradually, and no obvious changes were found in G2/M phase cells. Under the transmission electron microscopy, apoptotic bodies containing nuclear fragments were found in GA-treated K562 cells. After treatment with GA of 2.0 µmol/L for 24 h, the percentage of apoptotic cells was increased from 4.09% to 18.47% (P<0.01). Overexpression of hERG channel was found in K562 cells, while GA could down-regulate it at both protein and mRNA levels (P<0.01). It was concluded that GA exhibited its anti-leukemia effects partially through down-regulating the expression level of hERG channel in K562 cells, suggesting that GA may be a potential agent against leukemia with a mechanism of blocking hERG channel.SummaryOverexpression of human ether-à-go-go (eag) related gene (hERG) has been found in a broad range of human leukemia cell lines and primary human leukemia. The block of hERG protein might be a potential therapeutic strategy for leukemia. Gambogic acid (GA) has recently exhibited marked anti-tumor potency on solid tumors of various derivations. Here, we investigated the anti-leukemia effects of GA and its relation to the regulation of hERG in K562 leukemia cells in vitro. K562 cells were treated with various concentrations of GA (0.125–8.0 µmol/L) for 0–72 h. MTT assay was used to evaluate the inhibition effect of GA on the growth of K562 cells. Cell apoptosis was measured through both Annexin-V FITC/PI double-labeled cytometry and transmission electron microscopy. Cell cycle regulation was studied by a propidium iodide method. RT-PCR and Western blot were applied to detect the expression level of hERG in K562 cells. GA presented striking growth inhibition and apoptosis induction potency on K562 cells in vitro in a time- and dose-dependent manner. The IC50 value of GA for 24 h was 2.637±0.208 µmol/L. Moreover, GA induced K562 cells arrested in G0/G1 phase, accordingly, cells in S phase decreased gradually, and no obvious changes were found in G2/M phase cells. Under the transmission electron microscopy, apoptotic bodies containing nuclear fragments were found in GA-treated K562 cells. After treatment with GA of 2.0 µmol/L for 24 h, the percentage of apoptotic cells was increased from 4.09% to 18.47% (P<0.01). Overexpression of hERG channel was found in K562 cells, while GA could down-regulate it at both protein and mRNA levels (P<0.01). It was concluded that GA exhibited its anti-leukemia effects partially through down-regulating the expression level of hERG channel in K562 cells, suggesting that GA may be a potential agent against leukemia with a mechanism of blocking hERG channel.