Nasopharyngeal Carcinoma CNE-2Z Cells Research Articles

Synergistic effect of Hsp90 inhibitor ginkgolic acids C15꞉1 combined with paclitaxel on nasopharyngeal carcinoma.

Nasopharyngeal cracinoma is a kind of head and neck malignant tumor with high incidence and high mortality. Due to the characteristics of local recurrence, distant metastasis, and drug resistance, the survival rate of patients after treatment is not high. Paclitaxel (PTX) is used as a chemotherapy drug in treating nasopharyngeal carcinoma, but nasopharyngeal carcinoma cells are easy to develop resistance to PTX. Inhibition of heat shock protein 90 (Hsp90) can overcome common signal redundancy and resistance in many cancers. This study aims to investigate the anti-tumor effect of ginkgolic acids C15꞉1 (C15:1) combined with PTX on nasopharyngeal carcinoma CNE-2Z cells and the mechanisms. This experiment was divided into a control group (without drug), a C15:1 group (10, 30, 50, 70 μmol/L), a PTX group (5, 10, 20, 40 nmol/L), and a combination group. CNE-2Z cells were treated with the corresponding drugs in each group. The proliferation of CNE-2Z cells was evaluated by methyl thiazolyl tetrazolium (MTT). Wound-healing assay and transwell chamber assay were used to determine the migration of CNE-2Z cells. Transwell chamber was applied to the impact of CNE-2Z cell invasion. Annexin V-FITC/PI staining was used to observe the effect on apoptosis of CNE-2Z cells. The changes of proteins involved in cell invasion, migration, and apoptosis after the combination of C15꞉1 and PTX treatment were analyzed by Western blotting. Compared with the control group, the C15꞉1 group and the PTX group could inhibit the proliferation of CNE-2Z cells (all P<0.05). The cell survival rates of the C15꞉1 50 μmol/L combined with 5, 10, 20, or 40 nmol/L PTX group were lower than those of the single PTX group (all P<0.05), the combination index (CI) value was less than 1, suggesting that the combined treatment group had a synergistic effect. Compared with the 50 μmol/L C15꞉1 group and the 10 nmol/L PTX group, the combination group significantly inhibited the invasion and migration of CNE-2Z cells (all P<0.05). The results of Western blotting demonstrated that the combination group could significantly down-regulate Hsp90 client protein matrix metalloproteinase (MMP)-2 and MMP-9. The results of double staining showed that compared with the 50 μmol/L C15꞉1 group and the 10 nmol/L PTX group, the apoptosis ratio of CNE-2Z cells in the combination group was higher (both P<0.05). The results of Western blotting suggested that the combination group could decrease the Hsp90 client proteins [Akt and B-cell lymphoma-2 (Bcl-2)] and increase the Bcl-2-associated X protein (Bax). The combination of C15꞉1 and PTX has a synergistic effect which can inhibit cell proliferation, invasion, and migration, and induce cell apoptosis. This effect may be related to the inhibition of Hsp90 activity by C15꞉1.

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.

Opening of the CLC-3 chloride channel induced by dihydroartemisinin contributed to early apoptotic events in human poorly differentiated nasopharyngeal carcinoma cells.

Nasopharyngeal carcinoma (NPC) is a specific type of head and neck cancer that is prevalent in Southeast Asia. Dihydroartemisinin (DHA), a semisynthetic derivative of artemisinin, has specific anticancer activity. Here, we aimed to investigate the role of the CLC-3 chloride channel in the anticancer effect of DHA in poorly differentiated NPC CNE-2Z cells. First, we observed that DHA could specifically inhibit the proliferation, induce apoptosis, and increase cleaved caspase-3 expression in the CNE-2Z cells. Then, we found that DHA could activate chloride channels, which led to Cl- efflux and apoptotic volume decrease (AVD) in the early stage in the CNE-2Z cells. DHA also specifically increased CLC-3 chloride channel protein expression in the CNE-2Z cells. Silencing of the CLC-3 protein expression depleted the Cl- currents, and decreased the AVD capacity and cell apoptosis induced by DHA. Finally, we revealed that the [Ca2+ ]i increased after around 6 hours of treatment with DHA, which was also inhibited by silencing of the CLC-3 protein expression. Our data demonstrated that the selective antitumor activities of DHA in NPC may occur through the specific activation of the CLC-3 Cl- channel, leading to Cl- efflux, and induced AVD, then led to [Ca2+ ]i accumulation and caspase-3 activation, and finally induced apoptosis. The activation of the CLC-3 chloride channel played an essential and proximal upstream role in the antitumor activities of DHA.

Long chain non-coding RNA MALAT-1 gene knockdown inhibits growth and migration and promotes apoptosis of human laryngeal squamous cell carcinoma Hep-2 cells in vitro

To investigate the effect of knocking down long chain non-coding RNA MALAT-1 gene on the biologicalbehaviors of human laryngeal squamous cell carcinoma Hep-2 cells. With immortalized nasopharyngeal epithelial(NPE) cell line NP-69 as the reference, MALAT1 expression in FaDu, Hep-2 and nasopharyngeal carcinoma CNE-2Z cells weredetected using real-time PCR. Hep-2 cells were transfected with shmalat1 lentivirus and the expression of MALAT1 wasdetected. MTT assay, flow cytometry, Transwell assay and M Atrigel invasiveness test were used to evaluate the effect ofMALAT-1 knockdown on the proliferation, cell cycle, cell apoptosis, migration, and invasiveness of Hep-2 cells. Compared with NP-69 cells, Hep-2 cells, FaDu cells, and CNE-2Z cells all showed significantly increased MALAT-1expression. In Hep-2 cells, knockdown of MALAT-1 significantly inhibited the cell proliferation, increased the cell percentagein S phase (P < 0.01), decreased the cell percentage in G2/M phase (P < 0.01), and attenuated the migration and invasiveness of thecells. MALAT-1 is over-expressed in laryngeal squamous cell carcinoma, and knocking down MALAT-1 gene cansignificantly suppress the proliferation, invasion and migration and promotes apoptosis of the cancer cells.

The apoptotic effect of Zoledronic acid on the nasopharyngeal carcinoma cells via ROS mediated chloride channel activation.

Zoledronic acid (ZA), a third-generation bisphosphonate, has been applied for treatment of bone metastases caused by malignant tumors. Recent studies have found its anti-cancer effects on various tumor cells. One of the mechanisms of anti-cancer effects of ZA is induction of apoptosis. However, the mechanisms of ZA-induced apoptosis in tumor cells have not been clarified clearly. In this study, we investigated the roles of chloride channels in ZA-induced apoptosis in nasopharyngeal carcinoma CNE-2Z cells. Apoptosis and chloride current were induced by ZA and suppressed by chloride channel blockers. After the knockdown of ClC-3 expression by ClC-3 siRNA, ZA-induced chloride current and apoptosis were significantly suppressed, indicating that the chloride channel participated in ZA-induced apoptosis may be ClC-3. When reactive oxygen species (ROS) generation was inhibited by the antioxidant N-acetyl-L-cysteine (L-NAC), ZA-induced apoptosis and chloride current were blocked accordingly, suggesting that ZA induces apoptosis through promoting ROS production and subsequently activating chloride channel.

Shikonin induces necroptosis by reactive oxygen species activation in nasopharyngeal carcinoma cell line CNE-2Z.

Shikonin, a natural small agent, has shown inhibitory effect in many kinds of cells, which increases intracellular reactive oxygen species (ROS) level and causes mitochondrial injury. In this study, shikonin showed good inhibitory effect on nasopharyngeal carcinoma CNE-2Z cells in vivo and vitro. The results presented here revealed that ROS levels increased markly after shikonin treated. The electron microscopy displays the change in ultrastructure of CNE-2Z cells after treatment for shikonin, which indicated that shikonin induced necroptosis. Shikonin-induced cell death was inhibited by a necroptosis inhibitor, necrostatin-1 (Nec-1), while the activity was unaffected by the caspase inhibitor z-VAD-fmk. Furthermore, we have demonstrated that the activation of receptor-interacting kinase (RIP) led to necroptosis. Meanwhile, shikonin also significantly inhibited tumor growth in a CNE-2Z xenograft mouse model. Taken together, shikonin induced CNE-2Z cells death by producing ROS as a necroptosis inducer. It could serve as a new therapeutic agent for treating CNE-2Z cells.

The selective cytotoxicity of DSF-Cu attributes to the biomechanical properties and cytoskeleton rearrangements in the normal and cancerous nasopharyngeal epithelial cells

Cancer initiation and progression follow complex changes of cellular architecture and biomechanical property. Cancer cells with more submissive (or “softer”) than their healthy counterparts attributed to the reorganization of the complex cytoskeleton structure, may be considered as a potential anti-tumor therapeutic target. In this study, atomic force microscopy (AFM) was carried out to detect the topographical and biophysical changes of nasopharyngeal carcinoma CNE-2Z cells and normal nasopharyngeal epithelial cells NP69-SV40T by treating the Disulfiram chelated with Cu2+ (DSF-Cu). DSF-Cu induced the apoptotic population, ROS production and decreased the NF-κB-p65 expression of CNE-2Z cells, which was much higher than those of NP69-SV40T cells. DSF-Cu caused the obvious changes of cell morphology and membrane ultrastructure in CNE-2Z cells. The roughness decreased and stiffness increased significantly in CNE-2Z cells, which correlated with the rearrangement of intracellular F-actin, FLNa and α-tubulin structures in CNE-2Z cells. And the adhesion force of CNE-2Z cells was also increased accompanied with the increased E-cadherin expression. However, these results could not be observed in the NP69-SV40T cells even the concentration of DSF reached up to 400nM. Finally, the detection of cell wound scratch assay confirmed DSF-Cu could inhibit the migration of CNE-2Z cells, but no effect on NP69-SV40T cells. These findings demonstrated the selective cytotoxicity of DSF-Cu in CNE-2Z cells may attribute to the different mechanical properties and cytoskeleton rearrangement from the normal nasopharyngeal epithelial cells.

ClC-3 Chloride Channel Proteins Regulate the Cell Cycle by Up-regulating cyclin D1-CDK4/6 through Suppressing p21/p27 Expression in Nasopharyngeal Carcinoma Cells.

It was shown in this study that knockdown of ClC-3 expression by ClC-3 siRNA prevented the activation of hypotonicity-induced chloride currents, and arrested cells at the G0/G1 phase in nasopharyngeal carcinoma CNE-2Z cells. Reconstitution of ClC-3 expression with ClC-3 expression plasmids could rescue the cells from the cell cycle arrest caused by ClC-3 siRNA treatments. Transfection of cells with ClC-3 siRNA decreased the expression of cyclin D1, cyclin dependent kinase 4 and 6, and increased the expression of cyclin dependent kinase inhibitors (CDKIs), p21 and p27. Pretreatments of cells with p21 and p27 siRNAs depleted the inhibitory effects of ClC-3 siRNA on the expression of CDK4 and CDK6, but not on that of cyclin D1, indicating the requirement of p21 and p27 for the inhibitory effects of ClC-3 siRNA on CDK4 and CDK6 expression. ClC-3 siRNA inhibited cells to progress from the G1 phase to the S phase, but pretreatments of cells with p21 and p27 siRNAs abolished the inhibitory effects of ClC-3 siRNA on the cell cycle progress. Our data suggest that ClC-3 may regulate cell cycle transition between G0/G1 and S phases by up-regulation of the expression of CDK4 and CDK6 through suppression of p21 and p27 expression.

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.

1 T moderate intensity static magnetic field affects Akt/mTOR pathway and increases the antitumor efficacy of mTOR inhibitors in CNE-2Z cells

Static magnetic field (SMF) has been known to affect cell proliferation in a cell-type-dependent manner, while the mechanism still remains unclear. We found that 1T moderate intensity SMF inhibits cell proliferation of nasopharyngeal carcinoma CNE-2Z cells and the Akt/mTOR signaling pathway, which is upregulated in many cancers. mTOR inhibitors are potential chemodrugs, but their clinical effects are limited by the feedback reactivation of other signaling components such as EGFR and Akt. We showed that 1T SMF increases the antitumor efficacy of mTOR inhibitor Torin 2. In addition, 1T SMF increases the inhibition efficiency on mTOR substrates phosphorylation and represses the mTOR inhibitor-induced feedback reactivation of EGFR and Akt. Our study not only demonstrates that mTOR/Akt pathway is one of the molecular targets of SMFs in cells, but also reveals the clinical potentials of combinations of mTOR inhibitors and SMFs in cancer treatment.

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.

The ClC-3 chloride channel associated with microtubules is a target of paclitaxel in its induced-apoptosis

Recent evidences show that cationic fluxes play a pivotal role in cell apoptosis. In this study, the roles of Cl− channels in paclitaxel-induced apoptosis were investigated in nasopharyngeal carcinoma CNE-2Z cells. Chloride current and apoptosis were induced by paclitaxel and inhibited by chloride channel blockers. Paclitaxel-activated current possessed similar properties to volume-activated chloride current. After ClC-3 was knocked-down by ClC-3-siRNA, hypotonicity-activated and paclitaxel-induced chloride currents were obviously decreased, indicating that the chloride channel involved in paclitaxel-induced apoptosis may be ClC-3. In early apoptotic cells, ClC-3 was up-regulated significantly; over-expressed ClC-3 was accumulated in cell membrane to form intercrossed filaments, which were co-localized with α-tubulins; changes of ultrastructures and decrease of flexibility in cell membrane were detected by atomic force microscopy. These suggest that ClC-3 is a critical target of paclitaxel and the involvement of ClC-3 in apoptosis may be associated with its accumulation with membrane microtubules and its over activation.

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.