Effect of extract of Oratosquilla oratoria on telomerase activity in human nasopharyngeal carcinoma cell line

AIM: To study the inhibitory effect and its mechanisms of the extract of Oratosquilla oratoria (EOS) on the activity of telomerase in human nasopharyngeal carcinoma cell line CNE-2Z. METHODS: MTT assay was used to determine the effect of different doses of EOS on the proliferation of CNE-2Z cells. The activity of telomerase was analyzed by TRAP-ELISA. The mRNA expression of hTERT was determined by RT-PCR, and the protein expression of c-Myc was detected by Western blotting. RESULTS: EOS inhibited the proliferation of CNE-2Z cells in a dose-dependent manner (P<0.01). Telomerase activity was decreased, the mRNA expression of hTERT and c-Myc in CNE-2Z cells was also decreased (P<0.01) by the treatment of EOS. The correlation between the down-regulatory expression of hTERT mRNA and inhibitory expression of c-Myc protein (P<0.05) under the condition of EOS exposure was observed. CONCLUSION: EOS inhibits the proliferation of CNE-2Z cells by reducing the activity of telomerase, which is related with the inhibitory expression of hTERT mRNA caused by the decrease in c-Myc production.     

Inhibitory effect of extract of Oratosquilla on migration and vasculogenic mimicry in human nasopharyngeal carcinoma cell line in vitro

AIM: To study the inhibitory effect of the extract of Oratosquilla (EOS) on the migration and vasculogenic mimicry in human poorly differentiated nasopharyngeal carcinoma cell line CNE-2.METHODS: CNE-2 cells were cultured in the medium with different concentrations of EOS (0 mg/L, 125 mg/L, 250 mg/L and 500 mg/L). The migration of CNE-2 cells and the formation of tube-like structures (TLSs) by CNE-2 cells were determined with wound healing assay and in vitro anti-angiogenesis test, respectively. The formation of TLSs by CNE-2 cells and their structural characteristics were observed by anti-angiogenesis test on the Matrigel. The protein expression of fascin 1 and vascular endothelial growth factor (VEGF) was detected by Western blotting.RESULTS: Compared with control group, EOS significantly decreased the migration velocity of CNE-2 cells in a dose-dependent manner. CNE-2 cells formed TLSs on the Matrigel, and the formation of TLSs by CNE-2 cells was inhibited by EOS in a dose-dependent manner. The expression of fascin 1 and VEGF in CNE-2 cells was also decreased after treatment with EOS. A positive correlation between the expression of fascin 1/VEGF and the formation of TLSs by CNE-2 cells was observed.CONCLUSION: CNE-2 cells form TLSs on the Matrigel, and EOS inhibits the migration and vasculogenic mimicry of CNE-2 cells, which are related with down-regulating the expression of fascin 1 and VEGF in CNE-2 cells.     

X-ray ionizing radiation induces epithelial-mesenchymal transition in human nasopharyngeal carcinoma CNE-2 cells

AIM:To investigate the effect of X-ray ionizing radiation on epithelial-mesenchymal transition (EMT) in human nasopharyngeal carcinoma CNE-2 cells and its involved potential signaling pathway. METHODS:The nasopharyngeal carcinoma CNE-2 cells were irradiated with different doses (0 Gy, 2 Gy, 4 Gy and 8 Gy) of X-ray. The morphological changes of the cells were observed under inverted microscope after 24 h. The migration and invasion abilities were detected by wound healing and Transwell assays. The mRNA and protein levels of E-cadherin, N-cadherin and vimentin in nasopharyngeal carcinoma CNE-2 cells were determined by real-time PCR and Western blot, respectively. The protein levels of Akt and p-Akt were detected by Western blot. RESULTS:After X-ray irradiation, the CNE-2 cells exhibited typical ‘cobblestone’ or spindle-like shape, with extended pseudopodia and dilated intercellular space. The invasiveness and metastatic abilities of the CNE-2 cells were enhanced (P<0.01). The mRNA and protein expression levels of E-cadherin were significantly decreased (P<0.01), while the mRNA and protein expression levels of N-cadherin and vimentin were markedly increased after irradiation as compared with the control group (no irradiation) (P<0.05). The protein level of p-Akt was significantly enhanced (P<0.01), while the protein level of Akt showed little change after irradiation. CONCLUSION:X-ray ionizing radiation induces EMT in nasopharyngeal carcinoma CNE-2 cells, which may be related to the activation of PI3K/Akt signaling pathway.     

Inhibitory role of epigallocatechin-3-gallate in proliferation of human nasopharyngeal carcinoma cells by targeting P53/miR-34a

AIM: To study the effect of epigallocatechin-3-gallate(EGCG) on the proliferation of human nasopharyngeal carcinoma(NPC) cells, and to explore its mechanism by targeting miR-34a.METHODS: Nasopharyngeal carcinoma CNE-2Z cells were treated with various concentrations of EGCG. The ability of cell proliferation was detected by CCK-8 assay, 5-ethynyl-2-deoxyuridine(EdU) incorporation assay and colony-forming assay. The cell cycle distributions were analyzed by flow cytometry. The protein levels of P53 and Notch1 were detected by Western blot. The expression of miR-34a and Notch1 mRNA was measured by real-time PCR.RESULTS: EGCG effectively inhibited the proliferation and colony formation of CNE-2Z cells in a dose-dependent manner, which was related to its induction of cell cycle arrest at G₀/G₁ phase. The expression of P53 and miR-34a in CNE-2Z cells was significantly increased after treated with EGCG, while the expression of Notch1 at mRNA and protein levels was markedly suppressed.CONCLUSION: EGCG induces cell cycle arrest and suppresses cell proliferation by regulating the P53/miR-34a/Notch1 pathway in NPC cells.     

miRNA-7-mediated Bax/Bcl-2 expression promotes apoptosis of human nasopharyngeal carcinoma CNE-1 cells

AIM: To investigate the relationship of microRNA-7 (miRNA-7) over-expression and Bax/Bcl-2 expression in human nasopharyngeal carcinoma CNE-1 cells.METHODS: The CNE-1 cells were transfected with miRNA-7 mimics using Lipofectamine 2000. The expression of miRNA-7 was detected by real-time PCR. CCK-8 assay and Hoechst 33258 staining were used to detect the cell activity and apoptosis. The expression of Bax/Bcl-2 at mRNA and protein levels was determined by real-time PCR and Western blot. RESULTS: The expression of miRNA-7 was increased significantly in the CNE-1 cells compared with negative control group and mock group (P<0.01). The activity of CNE-1 cells were extremely decreased after tansfected with miRNA-7 mimics (P<0.01). The typical apoptotic nuclear morphological changes were observed in the CNE-1 cells under the fluorescence microscope with Hoechst 33258 staining. The expression of Bax at mRNA and protein levels was significantly increased compared with the other 2 groups (P<0.01), while the Bcl-2 expression at mRNA and protein levels was significantly down-regulated (P<0.01).CONCLUSION: Over-expression of miRNA-7 significantly inhibits the growth and promotes the apoptosis of nasopharyngeal carcinoma CNE-1 cells by increasing the expression of Bax and down-regulating Bcl-2.     

Effect of protein kinase C-α antisense oligonucleotide on cell cycle of CNE-2Z cells

AIM:To observe the effect of protein kinase C-α(PKCα)antisense oligonucleotide on cell growth, cell cycle and the expression of cyclin E in human poor-differentiated nasopharyngeal carcinoma(NPC) cell line CNE-2Z. METHODS:Antisense PKCα was transfected by cationic liposome(LP) in CNE-2Z cells to analyze the cell growth and cell cycle by MTT colorimetric assay and flow cytometry, respectively. Moreover, the expression of cyclin E was determined by immunocellularchemistry and scanning the result of dot-blotting. RESULTS:①With the concentration of antisense PKCα increasing, the relative cell growth index was decreased gradually(P＜0.01). ②After treated with antisense PKCα, the percentage of cells in G₁ phase enhanced(P＜0.05). ③Compared with the control group, the expressing intensity of cyclin E reduced in antisense PKCα group, and the expression of cyclin E decreased to 66.5%±18.4％(P＜0.05) of the control by scanning quantitative analysis. CONCLUSION:These results indicated that antisense PKCα may inhibit cell growth in CNE-2Z via suppressing the expression of cyclin E and hindering cell process in G₁ phase.     

Role of ClC-3 chloride channel in inhibition of nasopharyngeal carcinoma cell cycle by metformin

AIM: To study the roles of ClC-3 chloride channel in the inhibition of nasopharyngeal carcinoma cell cycle by metformin. METHODS: The CNE-2Z cells were treated with metformin at different concentrations. The viability of CNE-2Z cells was measured by CCK-8 assay. The cell cycle distribution was detected by flow cytometry. The protein expression of ClC-3 was determined by Western blot. The Cl^- currents was record by the patch-clamp technique. In addition, the cell cycle distribution was analyzed in the nasopharyngeal carcinoma CNE-2Z cells which over-expressed ClC-3 by pEZ-M03-ClC-3 plasmid transfection. RESULTS: Metformin inhibited the viability of CNE-2Z cells at 5, 10 and 20 mmol/L. Metformin at 10 mmol/L prevented the activation of chloride currents induced by hypotonicity, inhibited the protein expression of ClC-3 chloride channel and arrested the nasopharyngeal carcinoma CNE-2Z cells at G₀/G₁ phases. ClC-3 chloride channel protein over-expression reversed the effect of metformin on the cell cycle distribution of CNE-2Z cells. CONCLUSION: Metformin inhibits the CNE-2Z cell cycle, which may be related to the inhibition of ClC-3 chloride channel function and protein expression.     

Inhibitory effect of polypeptide from Buthus martensii Karsch on neoplasm cells

AIM: To observe the inhibitory effects of polypeptide from Buthus martensii venom (PBMV) on human tumor cell lines and the influence of PBMV on cell cycle migration, expression of tumor-suppressor gene p53 and the membrane potential of CNE-2Z cells. METHODS: MTT colorimetric method, the colony formation and mitosis index, flow cytometry assay and intracellular recording with glass microelectrodes were used. RESULTS: PBMV had obvious cytotoxicity on several tumor cell lines. The cells grow was inhibited by PBMV, colony formation rate and mitotic index of tumor cells were reduced and the number of polykaryocyte was decreased. CNE-2Z cells in S phase were reduced evidently after they were treated with PBMV (P<0.01). After CNE-2Z cells were incubated with PBMV, P53 protein expression in the cells decreased obviously. Differences were very distinct (P<0.01). The negative potential of cell membrane reduced evidently and cell membrane was in depolarization state. CONCLUSION: PBMV probably possesses the effects of the "membrane toxin". By decreasing the membrane potential, the growth and proliferation of tumor cells were interfered by PBMV.     

Effect of arctigenin on apoptosis of human nasopharyngeal carcinoma cell line CNE-1

AIM: To investigate the effect of arctigenin on the apoptosis of human nasopharyngeal carcinoma cell line CNE-1 and its potential mechanism. METHODS: The inhibition of cell viability was analyzed by CCK-8 assay. The activity of caspase-3 and caspase-9 was analyzed by caspase-3 and caspase-9 activity kit. Apoptotic cell percentage was evaluated by Annexin V-PI staining. The expression of PI3K/AKT/XIAP signal pathway-related molecules at mRNA and protein levels was analyzed by real-time PCR and Western blot. RESULTS: Arctigenin inhibited the cell activity in a dose- and time-dependent manner after treatment with arctigenin at concentrations of 10, 20, 40 and 80 μmol/L for 24 h, 48 h and 72 h (P<0.01). Arctigenin also increased the activity of caspase-3 and caspase-9 and the apoptotic rate (P<0.05), and down-regulated the mRNA and protein expression of PI3K/AKT/XIAP signal pathway-related molecules (P<0.05).CONCLUSION: Arctigenin induces the apoptosis of CNE-1 cells through PI3K/AKT/XIAP signal pathway.     

Knockdown of IK1 potassium channel inhibits expression and function of ClC-3 chloride channel

AIM: To investigate whether the ClC-3 chloride channel is an acting target of the IK1 potassium channel, and to study the action of IK1 potassium channel on the functional activities and expression of ClC-3 chloride channels. METHODS: IK1 gene was silenced by IK1 siRNA in poorly-differentiated nasopharyngeal carcinoma cells (CNE-2Z). Real-time PCR and Western blot were used to detect the expression of ClC-3 at mRNA and protein levels. The distribution of ClC-3 protein in the cells was observed under confocal immunofluorescence microscope. The chloride current was recorded by the patch-clamp technique. RESULTS: IK1 siRNA was successfully transfected into the CNE-2Z cells and knocked down the expression of IK1 potassium. The mRNA expression of ClC-3 was increased by the IK1 siRNA. IK1 siRNA inhibited the expression of ClC-3 protein. A chloride current was activated by hypotonic challenges, and the hypotonicity-induced current was reduced in the cells which successfully transfected with IK1 siRNA. CONCLUSION: The knockdown of IK1 potassium channels inhibits the expression and function of ClC-3 chloride channel.     

Effects of PKC-α asODN and PKA-ⅠasODN on growth and proliferation of the CNE-2Z cells of nasopharyngeal carcinoma

AIM:To investigate the effects of antisense oligonucleotides (asODN) of PKC-α and PKA-Ⅰon growth and proliferation of the CNE-2Z cells.METHODS:The expression of PKC-α and PKA-Ⅰ was observed with immunohistochemistry method. The asODNs of (1)PKC-α, (2)PKA-Ⅰ, (3)PKC-α and PKA-Ⅰ, were transfected into CNE-2Z cells by lipofectin (LP), and a random sequence as a control was used. The cell growth index (GI) and the clone formation rate of CNE-2Z were detected by MTT colorimetric assay and soft agar assy, respectively.RESULTS:The expression of PKC-α or PKA-Ⅰin CNE-2Z in experimental group were both significantly lower than that of control group(P<0.05). The GI and clone formation rates of CNE-2Z cells transfected by PKC-α and PKA-ⅠasODN with concentrations ranging from 0.05 μM to 1.00 μM were lower significantly than that of control groups(P<0.05), and there was a dose-dependent relationship among them. The inhibitory effects of PKC-α and PKA-ⅠasODNs both on the cell growth index (GI) and clone formation rates were more significant than that of control group(P<0.01),and the GI were significantly lower than that of the other experimental groups(P<0.05).CONCLUSION:PKC-α asODN and PKA-ⅠasODN inhibited CNE-2Z growth and proliferation in vitro, and a synergetic inhibitory effect of PKC-α asODN and PKA-ⅠasODN was also observed.     

Roles of chloride channels in the migration of nasopharyngeal carcinoma cells at different stages of the cell cycle

AIM: To clarify the migration capability of nasopharyngeal carcinoma cells (CNE-2Z) at different stages of the cell cycle and the roles of chloride channels in cell migration. METHODS: Synchronous cells were obtained by the serum deprivation，double chemical-block, mitotic arrest and shake-off techniques. Cell cycle distribution of CNE-2Z cells was analyzed by the flow cytometry. Migration rate was assayed by transwell chambers and by image analysis. The cytotoxicity of chemicals on cells was tested by MTT assay. RESULTS: CNE-2Z cells at different stages of the cell cycle exhibited different migratory ability. The migration rate of the three stages was G1>M> S. The migration of CNE-2Z cells was inhibited by chloride channel blockers (ATP, NPPB and tamoxifen), but the inhibitory effect of the blockers varied with cells at different stages. CONCLUSIONS: The migratory ability is associated with the cell cycle in CNE-2Z cells. Chloride channels play an important role in cell migration of CNE-2Z cells.     

Establishment of nasopharyngeal carcinoma (NPC) cell lines stable expressing NPC-derived LMP1

AIM: To establish nasopharyngeal carcinoma(NPC) cell lines stable expressing NPC-derived latent membrane protein 1(LMP1) gene.METHODS:General expression vector and epithelium-specific expression vector of NPC-derived LMP1 gene were constructed by using recombinant techniques, then transfected these vectors into a poor differentiated NPC cell line named CNE-2 ,integration and expression of N-LMP1 in CNE-2 cells were detected by PCR,RT-PCR and Western blot. RESULTS:(1) General expression vector and epithelium-specific expression vector of NPC-derived LMP1 gene were constructed successfully.(2) It showed that N-LMP1 gene expressed in CNE-2 cells correctly.CONCLUSION: The first NPC cell lines which stable express NPC-LMP1 were established. The cell lines obtained will provide important basis for exploring the role of NPC-LMP1 in nasopharynx carcinogenesis.     

Effect of hypoxia-inducible factor-1α knockdown by siRNA on viability and CEACAM1 expression in oral squamous cell carcinoma

AIM: To investigate the relationship between hypoxia-inducible factor-1α (HIF-1α) and viability and apoptosis of oral squamous cell carcinoma and its mechanism. METHODS: The expression of HIF-1α and carcinoembryonic antigen-related cell adhesion molecular 1 (CEACAM1) at mRNA and protein levels in oral squamous cell carcinoma cell lines Tca8113 and CAL27 and normal epithelial cell line NOK was determined by RT-PCR and Western blot. The expression of HIF-1α in CAL27 cells was silenced by RNA interference (RNAi) technique. The cells were divided into blank control group, non-sense control group and siRNA-HIF-1α group. The viability of CAL27 cells was measured by MTT assay and the apoptotic rate was analyzed by flow cytometry. The protein levels of HIF-1α, P21, vascular endothelial growth factor (VEGF), Bcl-2 and Bax were examined by Western blot. RESULTS: The expression of HIF-1α and CEACAM1 in oral squamous cell carcinoma cells was significantly higher than that in normal cells (P<0.05), and the expression of HIF-1α and CEACAM1 was positively correlated. The protein expression of HIF-1α in siRNA-HIF-1α group was significantly lower than that in blank control group (P<0.05). Knockdown of HIF-1α significantly inhibited CAL27 cell viability (P<0.05), promoted apoptosis (P<0.05), increased the protein levels of P21 and Bax (P<0.05), and significantly decreased the levels of VEGF and Bcl-2 (P<0.05). CONCLUSION: HIF-1α is over-expressed in oral squamous cell carcinoma. Knockdown of HIF-1α significantly inhibits cell viability and promotes apoptosis possibly through regulating the expression of HIF-1α downstream target genes and tumor angiogenesis.     

Over-expression of SATB1 mediates invasion and metastasis of nasopharyngeal carcinoma cells through epithelial-mesenchymal transition

AIM:To analyze the high expression of special AT-rich sequence-binding protein 1 (SATB1) in nasopharyngeal carcinoma (NPC) and its role in tumor invasion and metastasis. METHODS:The method of immunohistochemistry was used to detect the expression of SATB1 and epithelial-mesenchymal transition (EMT)-related molecules E-cadherin and vimentin in 76 cases of NPC and 61 cases of nasopharyngeal chronic inflammation (NPI), and the correlations of over-expression of SATB1 with NPC patients' clinical parameters as well as the expression of E-cadherin and vi-mentin were analyzed. Variously differentiated NPC cell lines CNE1, CNE2Z and C666-1 were cultured in vitro, and then SATB1-overexpressing cell line was screened. After interfering with SATB1 expression by siRNA, the expression of EMT-related molecules and the change of cell invasiveness were analyzed. RESULTS:The expression of SATB1 in the nasopharyngeal tissue was dominantly localized in the nuclei. The positive rate of SATB1 in NPC group was significantly higher than that in NPI group (P<0.01). E-cadherin was membrane-positive in NPI epithelial cells, while membrane E-cadherin in NPC was decreased but cytoplasmic expression was increased. The positive expression rate of membrane E-cadherin in NPI was significantly higher than that of NPC (P<0.01). Vimentin was localized in cytoplasm and negative in NPI epithelial cells, but the positive rate in NPC parenchymal cells was significant higher than that in NPI (P<0.01). The high expression of SATB1 in NPC was not related to the patents' sex, age, clinical classification and N classification, but positively correlated with T and M classification (P<0.05). Besides, high expression of SATB1 was positively correlated with vi-mentin in NPC tissues (r=0.358, P=0.009). SATB1 expression in NPC cell lines was negatively correlated with the levels of cell differentiation. Knockdown of SATB1 expression in C666-1 cells with siRNA was accompanied by an increase in E-cadherin and a decrease in vimentin levels, as well as a decrease in cell invasiveness. CONCLUSION:High expression of SATB1 promotes the clinical progress of NPC through EMT mechanism.     

miRNA-7 inhibits proliferation of human nasopharyngeal 5-8F carcinoma cells via EGFR/PI3K/Akt pathway

AIM:To investigate the relationship of microRNA-7 (miRNA-7) over-expression and epidermal growth factor receptor (EGFR)/phosphatidylinositol kinase-3 (PI3K)/protein kinase B (PKB, also called Akt) pathway in human nasopharyngeal carcinoma 5-8F cells. METHODS:The 5-8F cells were transfected with miRNA-7 mimics (carrying by Lipofectamine 2000). The expression of miRNA-7 was detected by real-time PCR. The cell proliferation was analyzed by CCK-8 assay. The cell colony-forming capability was determined by cell colony formation test. The expression of EGFR/PI3K/Akt at mRNA and protein levels was examined by real-time PCR and Western blotting. RESULTS:The expression level of miRNA-7 was significantly increased in 5-8F cells compared with negative control (NC) group and control group (P<0.01). The proliferation of NPC 5-8F cells was decreased extremely after tansfected with the miRNA-7 mimics (P<0.01), so did the result of the cell colony-formation test. The expression of EGFR/PI3K/Akt at mRNA and protein levels was significantly down-regulated compared with NC group and control group (P<0.01). CONCLUSION: Over-expression of miRNA-7 significantly inhibits the proliferation and colony-forming ability of nasopharyngeal carcinoma 5-8F cells by down-regulation of EGFR/PI3K/Akt pathway.     

Effects of curcumin analogue T83 on apoptosis of homologous nasopharyngeal carcinoma cells with different radioresistance

AIM：To compare the effect of T83 (a 4-arylidene curcumin analogue) on the apoptosis of homologous nasopharyngeal carcinoma cells with different radioresistance. METHODS：The effects of T83 on the viability, apoptosis, mitochondrial membrane potential (MMP), expression of procaspase-3/procaspase-9/Cyt-C proteins and relative PTEN/Akt/p27 mRNA expression in CNE-2R cells and CNE-2 cells were detected and compared by the methods of MTT assay, Hoechst staining, flow cytometry, Western blotting and qRT-PCR. RESULTS：T83 inhibited the viability of CNE-2R cells with the IC50 of 0.9,0.4 and 0.2 μmol/L for 24 h, 48 h and 72 h,respectively, which was more effective than that inhibiting the viability of CNE-2 cells with the IC50 of 1.8,0.5 and 0.4 μmol/L, respectively. After treated with T83 for 48 h, chromatin condensation, margination and splitting into a massive structure were observed in CNE-2R cells and CNE-2 cells,and the late apoptotic rate of CNE-2R cells was increased from 1.57% to 27.26%, which was higher than that of CNE-2 cells (1.74% to 8.15%). After treated with T83 for 36 h, the MMP in CNE-2R cells decreased by 87.71% and that decreased by 50.47% in CNE-2 cells. After treated with T83 for 48 h, the protein levels of procaspase-3 and procaspase-9 were decreased, and the protein level of Cyt-C was increased, which were more susceptible in CNE-2R cells than those in CNE-2 cells. After treated with T83 for 24 h, the relative mRNA expression of PTEN and p27 was significantly up-regulated, and the mRNA expression of Akt was down-regulated, which were more susceptible in CNE-2R cells than those in CNE-2 cells. CONCLUSION：Compared with CNE-2 cells, the inhibitory effect of T83 on the viability of CNE-2R cells is more specific by starting the mitochondrial apoptotic pathway, which is due to the inhibition of PTEN/Akt/p27 signaling pathway.