Huazhen Pan

Peking Union Medical College Hospital, Peping, Beijing, China

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Publications (5)7.31 Total impact

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    ABSTRACT: Our previous study has shown that sodium selenite can cause apoptosis in acute promyelocytic leukemia-derived NB4 cells in a caspase-dependent manner involving Deltapsim disruption and cleavage of Bcl-2, but more detailed mechanism(s) remain unclear. Here we showed that mitochondrial apoptosis signaling pathway played a vital role in apoptosis induced by sodium selenite based on the following findings: 1) cytochrome c release, activation of caspase 9, mitochondrial targeting, and oligermerization of Bax; 2) caspase 9, but not caspase 8, inhibitor could attenuate apoptosis; 3) downregulation of Bax and Bad by siRNA could delay sodium selenite-induced apoptosis. Further investigation showed that ROS was an essential inducer of deltapsim disruption and apoptosis by sodium selenite. Our findings here demonstrate that sodium selenite can induce apoptosis in NB4 cells through a mechanism involving ROS, activation of proapoptotic proteins Bad and Bax, Deltapsim disruption, release of cytochrome c, and consequent initiation of caspase cascade.
    Oncology Research Featuring Preclinical and Clinical Cancer Therapeutics 02/2009; 17(8):373-81. · 1.63 Impact Factor
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    ABSTRACT: The studies were carried out on nude mice bearing human colorectal carcinoma SW480 cell line xenografts to evaluate the chemotherapeutic potential of selenium containing compounds such as sodium selenite (SSe) and selenomethionine (SeMet). Three doses of anticancer drugs were used, including 0.1 mg/kg/day SSe (LSSe), 2 mg/kg/day SSe (HSSe), and 2 mg/kg/day SeMet. We explored the anticancer effect of SSe and SeMet administered by IP injection for 21 days. We observed the pathologic changes and the cell apoptosis in tumor tissue by HE staining and TUNNEL assay after HSSe and SeMet treatment. GSH level and antioxidant enzyme GPX activity in tumor tissues were assessed. In addition, Western blotting was used to detect the expression of apoptosis-related proteins. The results suggested that HSSe and SeMet had significantly inhibited tumor growth in vivo. We also observed the pathologic changes and cell apoptosis in tumor tissues after HSSe and SeMet treatment. GSH level was a bit increased but the GPX activity was reduced. Moreover, SSe and SeMet treatment downregulated the expression of the protein Bcl-xL, increased the expression of Bax, Bad, and Bim, and activated caspase-9. SSe and SeMet may be the selective, low-toxic anticancer agents to treat human colorectal carcinoma cancer.
    Oncology Research Featuring Preclinical and Clinical Cancer Therapeutics 01/2009; 18(1):1-8. · 1.63 Impact Factor
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    ABSTRACT: Our previous study has shown that sodium selenite can cause apoptosis in acute promyelocytic leukemia-derived NB4 cells in a caspase-dependent manner, but the detailed mechanism is unknown. Here we demonstrate a requirement for extracellular signal-regulated protein kinase (ERK) in mediating sodium selenite -induced apoptosis in NB4 cell. Though no apparent elevation of ERK activity was observed during the apoptosis in NB4 cells caused by 20 microM sodium selenite treatment, PD98059 and U0126, specific chemical inhibitors of the MEK/ERK signaling pathway, were shown to strongly prevent the apoptosis process, while ERK activator TPA enhanced the process. It is also known that p38 MAPK inhibitor SB203580 and JNK inhibitor SP600125 had slight effects on apoptosis. Further study indicated that ERK exerted its proapoptotic effect only at the early stage of apoptosis and played an antiapoptotic role at the later stages. Taken together, our findings suggest that ERK plays an active role in mediating sodium seleniteinduced apoptosis in NB4 cells.
    Journal of biochemistry and molecular biology 03/2007; 40(2):196-204. · 2.02 Impact Factor
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    ABSTRACT: To analyze the effect of Maltol on the apoptosis of Human Neuroblastoma Cells (SH-SY5Y) treated by free radical which was generated from Hydrogen Peroxide (H2O2), flow cytometry analysis on Phosphatidylserine (PS) inverting percentage was applied to determine the apoptosis. MTT (3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) assay was employed to analyze the cell viability. DNA electrophoresis was used to detect DNA fragmentation. Moreover intracellular calcium of concentration ([Ca2+]i) was measured by fluorescence emission. Flow cytometry analysis on the function of mitochondria and Western blot analysis of NF-kappaB. The results showed that the pretreatment with maltol for 2 hours could prevent the H2O2-induced apoptosis. Maltol could reduce the inverting percentage of PS, DNA fragmentation and [Ca2+]i, and enhance the cellular function of mitochondria. NF-kappaB activated by H2O2 is reduced. The experiments suggest that maltol could effectively inhibit the apoptosis induced by H2O2. As a novel anti-oxidant, maltol is a new promising drug in protecting the neurological cells from the damage by free radical.
    Journal of biochemistry and molecular biology 04/2006; 39(2):145-9. · 2.02 Impact Factor
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    ABSTRACT: To study the effects of low dose sodium selenite combined with all-trans retinoic acid (ATRA) on apoptosis and differentiation of human acute promyelocytic leukemia (APL) NB4 cells. Apo-ptosis was detected by translocation of phosphatidylserine (PS) with a Annexin-V kit and DNA fragmentation by agarose gel electrophoresis analysis, cell differentiation was studied by flow cytometry of CD(11b) expression and NBT reduction assay. Five micromol/L sodium selenite or 0.1 micromol/L ATRA alone could not induce apoptosis of NB4 cells within 48 hours. However, combination of the two drugs at the same doses as above could induce significant apoptosis in 48 hours characterized by increased PS translocation and DNA ladder. Sodium selenite at concentration of 2 micromol/L was not able to induce differentiation of NB4 cells, but when combined with 0.1 micromol/L ATRA, CD(11b) expression and NBT reduction were increased as compared with that of 0.1 micromol/L ATRA alone. Low dose sodium selenite could enhance the effects of low dose ATRA in inducing apoptosis and differentiation of NB4 cells.
    Zhonghua xue ye xue za zhi = Zhonghua xueyexue zazhi 01/2003; 23(12):628-30.