Human Nasopharyngeal Carcinoma CNE-2Z Cells Research Articles

Semisynthesis and anti-cancer properties of novel honokiol derivatives in human nasopharyngeal carcinoma CNE-2Z cells

In this study, 21 new honokiol derivatives were synthesised, and their anti-cancer properties were investigated. Among these, compound 1g exhibited the most potent cytotoxic activity against human nasopharyngeal carcinoma CNE-2Z cells, human gastric cancer SGC7901 cells, human breast cancer MCF-7 cells, and mouse leydig testicular cancer I-10 lines with IC50 values of 6.04, 7.17, 6.83, and 5.30 μM, respectively. Compared to the parental compound, 1g displayed up to 5.18-fold enhancement of the cytotoxic effect on CNE-2Z cells. We further demonstrated that 1g inhibited cell growth, suppressed migration and invasion, and induced apoptosis of CNE-2Z cells by down-regulating HIF-1α, MMP-2, MMP-9, Bcl-2, Akt and up-regulating Bax protein levels. Transfection of CNE-2Z cells with HIF-1α siRNA reduced cell migration and invasion. In addition, in vivo experiments confirmed that 1g inhibited tumour growth in CNE-2Z cell-xenografted nude mice with low toxicity. Thus, our data suggested that 1g was a potent and safe lead compound for nasopharyngeal carcinoma therapy.

Anti-Cancer Properties of Ginkgolic Acids in Human Nasopharyngeal Carcinoma CNE-2Z Cells via Inhibition of Heat Shock Protein 90.

Ginkgo biloba L. has been used in traditional Chinese medicine (TCM) for thousands of years. However, the anti-cancer properties of ginkgolic acids (GAS) isolated from G. biloba have not been investigated in human nasopharyngeal carcinoma cells. In this study, GAS exhibited an inhibitory effect on the ATPase activity of heat shock protein 90 (Hsp90) and anti-proliferative activities against four human cancer cell lines, with IC50 values ranging from 14.91 to 23.81 μg·mL−1. In vivo experiments confirmed that GAS inhibited tumor growth in CNE-2Z cell-xenografted nude mice with low hepatotoxicity. We further demonstrated that GAS suppressed migration and invasion and induced the apoptosis of CNE-2Z cells by inducing the degradation of Hsp90 client proteins (MMP-2, MMP-9, Her-2, c-Raf, Akt, and Bcl-2). Together, GAS are new Hsp90 inhibitors by binding to Hsp90 (hydrogen bond and hydrophobic interaction). Thus, GAS from G. biloba might represent promising Hsp90 inhibitors for the development of anti-nasopharyngeal carcinoma agents.

Magnetic Susceptibility Difference-Induced Nucleus Positioning in Gradient Ultrahigh Magnetic Field

Despite the importance of magnetic properties of biological samples for biomagnetism and related fields, the exact magnetic susceptibilities of most biological samples in their physiological conditions are still unknown. Here we used superconducting quantum interferometer device to detect the magnetic properties of nonfixed, nondehydrated live cell and cellular fractions at a physiological temperature of 37°C (310 K). It is obvious that there are paramagnetic components within human nasopharyngeal carcinoma CNE-2Z cells. More importantly, the magnetic properties of the cytoplasm and nucleus are different. Although within a single cell, the magnetic susceptibility difference between cellular fractions (nucleus and cytoplasm) could only cause ∼41–130 pN forces to the nucleus by gradient ultrahigh magnetic fields of 13.1–23.5 T (92–160 T/m), these forces are enough to cause a relative position shift of the nucleus within the cell. This not only demonstrates the importance of magnetic susceptibility in the biological effects of magnetic field but also illustrates the potential application of high magnetic fields in biomedicine.

Down-regulation of miR-205-5p enhances pro-apoptotic effect of 3-bromopyruvate on human nasopharyngeal carcinoma CNE2Z cells

To investigate the effect of down-regulation of miR-205-5p on 3-bromopyruvate-induced apoptosis in human nasopharyngeal carcinoma CNE2Z cells. Nasopharyngeal carcinoma CNE2Z cells were transfected with miR- 205-5p-mimic or miR-205-5p-inhibitor, treated with 80 μmol/L 3-bromopyruvate alone, or exposed to both of the treatments. The proliferation of the treated cells was examined with MTT assay, and early apoptosis of the cells was detected using a mitochondrial membrane potential detection kit (JC-1). DAPI fluorescence staining was used to detect morphological changes of the cell nuclei and late cell apoptosis; Annexin V-FITC/PI double staining was employed to detect the cell apoptosis rate. Western blotting was used to detect the expressions of Bcl-2, Bax, Mcl-1 and Bak proteins. Exposure to 3-bromopyruvate significantly inhibited the proliferation of CNE2Z cells, and increasing the drug concentration and extending the treatment time produced stronger inhibitory effects. Treatment with 80 μmol/L 3-bromopyruvate for 24, 48 and 72 h resulted in inhibition rates of (45.7±1.21)%, (64.4±2.02)% and (78.3±1.55)% in non-transfected CNE2Z cells, respectively; the inhibition rates were (27.7±1.04)%, (34.8±2.10)% and (44.3±1.57)% in the cells transfected with miR-205-5p-mimic, and were (80.5 ± 0.94)%, (87.9 ± 0.50)% and (93.8 ± 1.16)% in cells transfected with miR-205-5p-inhibitor, respectively. The results of mitochondrial membrane potential detection showed that the relative proportion of red and green fluorescence decreased significantly in miR-205-5p-inhibitor-transfected cells with 3-bromopyruvate treatment. Combined treatment of the cells with 3-bromopyruvate and miR-205-5p-inhibitor transfection obviously increased nuclear fragmentation and nuclear pyknosis and significantly increased cell apoptotic rate as compared with the two treatments alone (P < 0.01), causing also decreased expressions of Bcl-2 and Mcl-1 proteins and increased expressions of Bax and Bak proteins. Inhibition of miR-205-5p enhances the proapototic effect of 3-bromopyruvate in CNE2Z cells possibly in relation to the down-regulation of Mcl-1 and Bcl-2 and the up-regulation of Bak and Bax proteins.

Different properties between spontaneous and volume-activated chloride currents in human nasopharyngeal carcinoma and its normal counterpart cells.

Although the spontaneous chloride currents (SCC) have been well studied in the normal cells, its properties and roles in neoplasms cells are still unknown. Here, we found that the SCC was manifested in the poorly differentiated human nasopharyngeal carcinoma CNE-2Z cells, with some differences such as lower occurrence and bigger current density than those of the volume-activated chloride currents (VACC). NPPB, a chloride channel blocker, inhibited the SCC much stronger than the VACC. Down-regulation of chloride channel -3 (ClC-3), a volume and mechanically dependent ion channel, could significantly decrease the VACC, but not in SCC. The occurrence, latency, and mean density of the SCC were much lower in the normal nasopharyngeal NP69-SV40T cells than those in CNE-2Z cells. Our results demonstrated that the spontaneous electrical reactivity of neoplasm cells is higher than that of normal cells, which probably relates to their high physiological activity of neoplasm cells. SIGNIFICANCE OF THE STUDY: Spontaneous chloride currents (SCC) are well known in excitable tissues and regulate a variety of physiological and pathophysiological processes. During our researching on the volume-activated chloride currents (VACC) in human nasopharyngeal carcinoma CNE-2Z cells, SCC could be also observed with different properties from VACC. Meanwhile, the occurrence, latency, and mean density of the SCC were much higher in CNE-2Z cells than those in normal nasopharyngeal NP69-SV40T cells. Our results revealed the expression and characteristics of SCC in carcinoma cells and provided a preliminary experimental basis for further exploring the function of SCC in tumour cell biology.

Gambogenic acid triggers apoptosis in human nasopharyngeal carcinoma CNE-2Z cells by activating volume-sensitive outwardly rectifying chloride channel

Gambogenic acid (GNA) is one of the main components of Gamboge, and its anti-cancer effects have been well confirmed by previous researches. Nasopharyngeal carcinoma (NPC) has not been thoroughly studied, and the pathogenesis of NPC is unclear. Scientists have neither discovered effective therapies nor achieved a desirable prognosis. Some studies have found that the regulation of intra- and extracellular ion channels hinges directly on cell apoptosis, and treatment with GNA brings changes to the volume-sensitive outwardly rectifying chloride (VSOR Cl−) current of CNE-2Z cells recorded by the patch clamp method. Nevertheless, rarely have any researchers probed into the relevance between this variation and the anti-tumor mechanism of GNA. This paper is suggested that 2.0 μmol/L GNA activates VSOR Cl− currents on CNE-2Z cell membranes and that the activation of VSOR Cl− currents by GNA in CNE-2Z cells is blocked by the chloride channel blockers DIDS (400 μmol/L) and DCPIB (20 μmol/L). MQAE experiment further proves that GNA leads to the opening of chloride ion channel, which in turn results in the efflux of VSOR Cl− current; GNA induces the downregulation of GRP78 and the upregulation of ATF4 and CHOP proteins. These effects are correlated with endoplasmic reticulum (ER) stress. GNA can activate VSOR Cl− channels, leading to ER stress, inducing apoptosis and inhibiting proliferation in CNE-2Z cells.

Construction and identification of small hairpin RNA plasmids targeting neuropilin-1 gene and their inhibitory effect on human nasopharyngeal carcinoma CNE-2Z cell proliferation in vitro and in vivo

We observed the effects of small hairpin RNA (shRNA) plasmids targeting neuropilin-1 (NRP-1) gene on human nasopharyngeal carcinoma (NPC) CNE-2Z cell growth in vitro and in vivo. Three fluorescein-labeled shRNA eukaryotic expression vectors targeting NRP-1 gene, including pSilencer-shRNA1, pSilencer-shRNA2 and pSilencer-shRNA3 were constructed. The three plasmids were, respectively, transfected into human NPC CNE-2Z cells. The most effective plasmid was injected into xenograft tumors in nude mice. The sequencing for these recombinant plasmids was consistent with that of designed shRNA templates. Green fluorescence was seen in the transfected CNE-2Z cells and xenograft tumors in nude mice. MTT assay indicated that CNE-2Z cell proliferation was significantly inhibited. PT-PCR and Western blot displayed that both mRNA and protein of NRP-1 gene were all decreased, particularly in the cells treated with shRNA3. At the end of the experiment, xenograft tumors in plasmid group (0.599±0.002cm(3)) were significantly inhibited with a tumor inhibition rate of 48.6%, as compared to those in negative (1.141±0.013cm(3)) and blank control groups (1.165±0.308cm(3)) (all P<0.05). shRNA targeting NRP-1 gene can effectively inhibit human NPC CNE-2Z cell proliferation in vitro and in vivo. This provides an experiment basis for NPC gene therapy.

NRP-1/shRNA silencing suppresses nasopharyngeal carcinoma cell growth in vitro and in vivo

To investigate the effect of RNA interference (RNAi) targeting NRP-1 gene on the growth and proliferation of nasopharyngeal carcinoma (NPC) CNE-2Z cells. Short hairpin RNA (shRNA) plasmids targeting NRP-1 were designed and synthesized. These plasmids were respectively transfected into human NPC CNE-2Z cells and xenograft tumors in nude mice. The expressions of Fluorescein-labeled plasmids in NPC CNE-2Z cells and xenograft tumors were observed by fluorescence microscopy. Cell proliferation was detected by MTT assay. The inhibitory effects on target genes were evaluated with RT-PCR and Western blotting, respectively. The inhibitory effect of plasmids with the most effective sequence on xenograft tumors in nude mice was observed. CNE-2Z cell proliferation was significantly inhibited by NRP-1/shRNA silencing. RT-PCR showed NRP-1 mRNA expression was significantly decreased. Western blotting demonstrated the NRP-1/shRNA silencing can effectively inhibit the expression of target proteins in CNE-2Z cells. After six weeks, there were significant differences in the mean tumor volumes in nude mice between plasmid group and negative control group [(0.599±0.002) vs (1.141±0.013) cm(3), P<0.05] or blank control group [(0.599±0.002) vs (1.165±0.308) cm(3), P<0.05], and the inhibitory rate of tumor growth was 48.6%. RNA interference targeting NRP-1 can remarkably inhibit the growth of CNE-2Z cells in vitro and in vivo.

Influence of recombinant lentiviral vector encoding miR-15a/16-1 in biological features of human nasopharyngeal carcinoma CNE-2Z cells.

MicroRNAs can function as tumor suppressor miRNAs. Bcl-2 is an antiapoptotic gene overexpressed in many tumors, including nasopharyngeal carcinoma (NPC). It is reported that microRNA-15a (miR-15a) and microRNA-16-1 (miR-16-1) could act as bcl-2 inhibitors. To investigate their effects on NPC, the authors used recombinant lentiviral vector to upregulate the expression of miR-15a/16-1 in NPC CNE-2Z cells. The authors divided cells into the control group, transfection group, radiotherapy group, and transfection-radiotherapy group. In this experiment, reverse transcription-quantitative polymerase chain reaction was used to detect the expression of miR-15a/16-1 and bcl-2 mRNA. Cell proliferation was analyzed by MTT assay. Flow cytometry was used to measure cell apoptosis. Radiosensitivity was measured using colony-forming experiment. The protein expression of bcl-2 was measured by western blot, the activation levels of caspase were detected by a spectrophotometric method. After transfection, cell proliferation was inhibited, while the apoptosis rate and radiosensitivity were increased. In addition, the activation of caspase-2 and caspase-3 was aggrandized correspondingly. Although the expression levels of bcl-2 mRNA in each group had no difference, the protein expression of bcl-2 was downregulated. These results suggested that miR-15a/16-1 could inhibit cell proliferation and increase the apoptosis and radiosensitivity of CNE-2 cells, by regulating the bcl-2 gene at post-transcriptional level and by increasing the activation of caspase-2 and caspase-3.

Influence of recombinant lentiviral vector encoding miR-15a/16-1 in biological features of human nasopharyngeal carcinoma CNE-2Z cells

To study the influence of recombinant lentiviral vector encoding miR-15a/16-1 on biological features of human nasopharyngeal carcinoma CNE-2Z cells and underlying mechanisms. GFP-positive CNE-2Z cells transfected with recombinant lentiviral vector were selected. The experiment was divided into control group, transfected group, radiotherapy group, transfected-radiotherapy group. Cell proliferation was analyzed by MTT. Apoptosis was detected by flow cytometry. Radiotherapy sensitivity of the cells in control group and transfected group was evaluated by colony forming experiment. The expressions of miR-15a, miR-16-1 and bcl-2 mRNA were detected by real-time quantitative polymerase chain reaction (RT-qPCR). The expression of bcl-2 protein was detected by Western blot. The activation of Caspase-2 and Caspase-3 was evaluated by spectrophotometry. Relative expression quantities of miR-15a and miR-16-1 in infected group were 524.80 ± 40.79 (t = 494.611, P = 0.000) and 466.11 ± 40.96 (t = 386.8, P = 0.000), respectively. The proliferation of the cells in transfected-radiotherapy group was the most obvious, followed by the cells in radiotherapy group and transfected group (F = 424.3, P = 0.000). The apoptosis rates of control group, transfected group, radiotherapy group and transfected-radiotherapy group were (2.2 ± 1.4)%, (9.6 ± 0.8)%, (2.9 ± 1.1)%, and (18.6 ± 0.7)% respectively(F = 158.5, P = 0.000). Clonogenic assay showed that the values of SF2, Do (1.473) and Dq (1.581) in transfected group were lower than those in control group. The relative expression levels of bcl-2 mRNA in transfected group, radiotherapy group, and transfected-radiotherapy group had no significant difference (P > 0.05). Decrease in the expression of bcl-2 protein in transfected-radiotherapy group was most significantly, followed by that in transfected group. The percentages of activated Caspase-2 in control group, radiotherapy group, transfected group and transfected -radiotherapy group were 0.12 ± 0.01, 0.24 ± 0.04, 0.35 ± 0.02, and 0.44 ± 0.04, respectively (F = 115.500, P = 0.000). The percentages of activated Caspase-3 in the groups were 0.13 ± 0.01, 0.27 ± 0.01, 0.43 ± 0.02, and 0.83 ± 0.06, respectively (F = 439.921, P = 0.000). Recombinant lentiviral vector LV-miR15a/16-1 could improve the expression of miR-15a and miR-16-1 in CNE-2Z cells, inhibit the proliferation of CNE-2Z cells, promote apoptosis and enhance the sensitivity of the cells to radiotherapy probably by inhibiting bcl-2 expression, activating Caspase-2 and Caspase-3.

Transient overexpression of TGFBR3 induces apoptosis in human nasopharyngeal carcinoma CNE-2Z cells

NPC (nasopharyngeal carcinoma) is a common malignancy in southern China without defined aetiology. Recent studies have shown that TGFBR3 (transforming growth factor type III receptor, also known as betaglycan), exhibits anticancer activities. This study was to investigate the effects of TGFBR3 on NPC growth and the mechanisms for its actions. Effects of TGFBR3 overexpression on cell viability and apoptosis were measured by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide], AO/EB (acridine orange/ethidium bromide) staining and electron microscopy in human NPC CNE-2Z cells. The expression of apoptosis-related proteins, p-Bad, Bad, XIAP (X-linked inhibitor of apoptosis), AIF (apoptosis-inducing factor), Bax and Bcl-2, was determined by Western blot or immunofluorescence analysis. Caspase 3 activity was measured by caspase 3 activity kit and [Ca2+]i (intracellular Ca2+ concentration) was detected by confocal microscopy. Transfection of TGFBR3 containing plasmid DNA at concentrations of 0.5 and 1 μg/ml reduced viability and induced apoptosis in CNE-2Z in concentration- and time-dependent manners. Forced expression of TGFBR3 up-regulated pro-apoptotic Bad and Bax protein, and down-regulated anti-apoptotic p-Bad, Bcl-2 and XIAP protein. Furthermore, transient overexpression of TGFBR3 also enhanced caspase 3 activity, increased [Ca2+]i and facilitated AIF redistribution from the mitochondria to the nucleus in CNE-2Z cells, which is independent of the caspase 3 pathway. These events were associated with TGFBR3-regulated multiple targets involved in CNE-2Z proliferation. Therefore transient overexpression of TGFBR3 may be a novel strategy for NPC prevention and therapy.

ClC‐3 is a main component of background chloride channels activated under isotonic conditions by autocrine ATP in nasopharyngeal carcinoma cells

In this study, the activation mechanisms of the background chloride current and the role of the current in maintaining of basal cell volume were investigated in human nasopharyngeal carcinoma CNE-2Z cells. Under isotonic conditions, a background chloride current was recorded by the patch clamp technique. The current presented the properties similar to those of the volume-activated chloride current in the same cell line and was inhibited by chloride channel blockers or by cell shrinkage induced by hypertonic challenges. Extracellular applications of reactive blue 2, a purinergic receptor antagonist, suppressed the background chloride current in a concentration-dependent manner under isotonic conditions. Depletion of extracellular ATP with apyrase or inhibition of ATP release from cells by gadolinium chloride decreased the background current. Extracellular applications of micromolar concentrations of ATP activated a chloride current which was inhibited by chloride channel blockers and hypertonic solutions. Extracellular ATP could also reverse the action of gadolinium chloride. Transfection of CNE-2Z cells with ClC-3 siRNA knocked down expression of ClC-3 proteins, attenuated the background chloride current and prevented activation of the ATP-induced current. Furthermore, knockdown of ClC-3 expression or exposures of cells to ATP (10 mM), the chloride channel blockers 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) and tamoxifen, or reactive blue 2 increased cell volume under isotonic conditions. The results suggest that ClC-3 protein may be a main component of background chloride channels which can be activated under isotonic conditions by autocrine/paracrine ATP through purinergic receptor pathways; the background current is involved in maintenance of basal cell volume.

Effects of RNA interference targeting four different genes on the growth and proliferation of nasopharyngeal carcinoma CNE-2Z cells

To explore the effects of RNA interference targeting four different genes (VEGF, C-myc, Survivin, hTERT) on the growth and proliferation of nasopharyngeal carcinoma (NPC) CNE-2Z cells. Fluorescein-labeled short-hairpin (sh)RNA plasmids together and separately targeting VEGF, C-myc, Survivin and hTERT were built and respectively called plasmid-shVEGF-shC-myc-shSurvivin-shhTERT, plasmid-shVEGF, plasmid-shC-myc, plasmid-shSurvivin, plasmid-shhTERT. These plasmids were respectively transfected into human NPC CNE-2Z cells and xenograft tumors in nude mice. The expression of plasmids in NPC CNE-2Z cells and xenograft tumors was observed. Cell proliferation was detected with MTT assay. The mRNA and protein expression were determined by real-time PCR and western blot, respectively. The effects of plasmids on the biological behavior of CNE-2Z cells were observed with transwell invision chamber models. Apoptosis was determined with flow cytometer. The inhibitory effect of plasmids on xenograft tumors was observed in nude mice. The plasmid containing four different shRNAs could significantly inhibit CNE-2Z cell proliferation and decrease invasion ability in vitro compared with plasmids with each single shRNA (P<0.05). The plasmid containing four different shRNAs could simultaneously downregulate VEGF, C-myc, surviving, hTERT mRNA and protein expression in the CNE-2Z cells. The multiple gene shRNA could more significantly induce cell apoptosis than each single shRNA, respectively (P<0.05). The combinative silencing of these four genes had a better inhibitory effect on xenograft tumors than the silencing of each single shRNA (P<0.05). RNA interference targeting multiple genes can effectively inhibit NPC proliferation and induce apoptosis, which provides an experiment basis for NPC gene therapy.

Role of integrin αV in sensitivity to radiotherapy of human NPC

Objective To investigate whether the cell adhesion molecule integrin αV could influence the radiosensitivity of human nasopharyngeal carcinoma CNE-2Z cells via effecting intercellular effect.