[Show abstract][Hide abstract] ABSTRACT: Suppressors of cytokine signaling (SOCS) has emerged as a critical inhibitory molecule for controlling the cytokine response and antigen presentation by dendritic cells (DCs), thereby regulating the magnitude of both innate and adaptive immunity. The aim of this study was to investigate whether the SOCS1 antagonist pJAK2(1001-1013) peptide can weaken or block the inhibition function of SOCS1 in DCs by evaluating the phenotype, cytokine production, antigen-presenting and specific T-cell-activating capacity of DCs electroporated with human gastric cancer cell total RNA. Furthermore, the STAT1 activation of JAK/STAT signal pathway mediated by SOCS1 was analyzed by Western blot. Results demonstrated that the SOCS1 antagonist pJAK2(1001-1013) peptide up-regulated the expression of the maturation marker (CD83) and co-stimulatory molecule (CD86) of RNA-electroporated human monocyte-derived mature DCs (mDCs), potentiated the capacity of mDCs to induce T-cell proliferation, stimulated the secretion of pro-inflammatory cytokines, and enhanced the cytotoxicity of tumor cell antigen-specific CTLs activated by human gastric cancer cell total RNA-electroporated mDCs. Data from Western blot analysis indicated that STAT1 was further activated in pJAK2(1001-1013) peptide-loaded mDCs. These results imply that the SOCS1 antagonist pJAK2(1001-1013) peptide is an effective reagent to enhance antigen-specific antitumor immunity by DCs.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study is to investigate the effect of recombinant human leptin (rhLep) on the proliferation of human gastric cancer MGC-803 cells and its underlying mechanisms. RT-PCR was performed to identify the expression of leptin receptor (Ob-R). Cell proliferation was measured with MTT assay. DNA content and cell cycle were analyzed by flow cytometry. Apoptosis was assessed by DNA ladder assay and flow cytometry analysis using Annexin V-FITC/PI double staining. Underlying mechanisms of rhLep-induced apoptosis were evaluated by the activities of caspase-3, -8, -9, and cytochrome c release from mitochondria. Moreover, the phosphorylation of STAT3 in MGC-803 cells upon rhLep administration was detected by Western blot analysis. Our results demonstrated that two leptin receptors (Ob-Ra and Ob-Rb) were expressed in MGC-803 cells. rhLep diminished the proliferation rate of MGC-803 cells in a time- and concentration-dependent manner and induced MGC-803 cell apoptosis involving in the activation of caspase-8 and caspase-3 but not caspase-9. In addition, rhLep failed to induce cytochrome c release from mitochondria and had no effect on the activation of STAT3 in MGC-803 cells. Therefore, from these results, we concluded that rhLep significantly inhibited cell proliferation via G0/G1 phase cell cycle arrest and induced apoptosis through the extrinsic apoptotic pathway in human gastric cancer MGC-803 cells.
Clinical and Experimental Medicine 09/2012; 13(4). DOI:10.1007/s10238-012-0211-8 · 2.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Metformin acts as an energy regulator by activating 5'-adenosine monophosphate-activated protein kinase (AMPK), which is a key player in the regulation of energy homeostasis, but it is uncertain whether AMPK is its direct target. This study aims to investigate the possible interaction between metformin and AMPK. First, we verified that metformin can promote AMPK activation and induce ACC inactivation in human HepG2 cells using western blot. Then we predicted that metformin may interact with the γ subunit of AMPK by molecular docking analysis. The fluorescence spectrum and ForteBio assays indicated that metformin has a stronger binding ability to the γ subunit of AMPK than to α subunit. In addition, interaction of metformin with γ-AMPK resulted in a decrease in the α-helicity determined by CD spectra, but relatively little change was seen with α-AMPK. These results demonstrate that metformin may interact with AMPK through binding to the γ subunit.
[Show abstract][Hide abstract] ABSTRACT: Obesity is a known risk factor for postmenopausal cervical cancer. In human, plasma adiponectin (ADPN) levels are inversely
associated with obesity. ADPN may influence the pathogenesis of cervical cancer. In this paper, the effects of ADPN on the
proliferation of the cervical cancer HeLa cells and its underlying mechanism were studied. We discovered that two ADPN receptors
were expressed in HeLa cells and ADPN inhibited the proliferation of HeLa cells. Western-blotting showed that ADPN activated
AMP kinase in HeLa cells. Reverse transcriptase-polymerase chain reaction revealed ADPN down-regulated the expression of cell
cycle regulators cyclin D1 and c-myc, and induced the expression of p21WAF1/CIP1 and p53. These results indicate that ADPN inhibits proliferation and induces apoptosis of HeLa cells by altering the expression
of cell cycle regulators.
Key wordsadiponectin–adiponectin receptors–HeLa cell–proliferation–apoptosis