miRNA profiling of human nasopharyngeal carcinoma cell lines HONE1 and CNE2 after X-ray therapy

BACKGROUND

Radiotherapy is the main treatment for nasopharyngeal carcinoma. The radioresistance mechanism of cells is related to miRNAs.

OBJECTIVES

To investigate the miRNA profiling of HONE1 and CNE2 after X-ray therapy.

MATERIAL AND METHODS

The HONE1 and CNE2 cells were treated with X-ray at 4 Gy, 8 Gy, 16 Gy, and 20 Gy doses. The cell lines CNE2 with the best therapy effects and HONE1 with the worst therapy effects were screened out. Apoptosis and cell viability were detected with flow cytometry and Cell Counting Kit-8 (CCK-8). High-throughput sequencing was performed. A miRNA library was constructed. The miRNA annotation expression distribution, family prediction and target gene interaction, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were conducted.

RESULTS

The 24-hour 20 Gy dose X-rays were selected as the optimal therapy conditions. The CNE2_C, CNE2_M, HONE1_C and HONE1_M miRNAs accounted for 26.5%, 31.7%, 21.3%, and 22.9% of the Cleandata reads count, respectively, and the contents of rRNAs accounted for 24.9%, 14.7%, 25.1%, and 25.1% of the Cleandata reads count, respectively. The miRNAs with differential expression between the HONE1 and CNE2 cell lines including hsa-miR-21-5p, hsa-let-7a-5p, hsa-miR-125a-5p, hsa-miR-26a-5p, hsa-let-7f-5p, hsa-miR-20a-5p, and hsa-miR-24a-3p. There were also differentially expressed miRNAs in HONE1_C vs. HONE1_M, such as hsa-miR-21-5p and hsa-let-7i-5p. The differentially expressed miRNA in CNE2_C vs. CNE2_M was hsa-miR-148b-3p. The Gene Ontology analysis showed that the differentially expressed miRNA interacting genes in HONE1_M vs. CNE2_M were mainly enriched in biological process such as negative and positive regulation of transcription from RNA polymerase II promoter, cellular component such as cytosol and molecular function such as protein binding factor. The KEGG pathway analysis revealed that the differentially expressed miRNA interacting genes in HONE1_M vs. CNE2_M were enriched in the cancer-related pathways, such as pathways in cancer, MAPK signaling pathway and Wnt signaling pathway.

CONCLUSIONS

Twelve miRNAs and 9 genes which contribute to X-ray radiation resistance were identified. Among those with differential expression between the HONE1 and CNE2 cell lines, which played a regulatory role in multiple pathways, were hsa-miR-20a-5p, hsa-let-7a-5p, hsa-let-7f5p, hsa-let-7i-5p, hsa-miR-30e-5p, hsa-miR-148b-3p, and hsa-miR-200c-3p. The corresponding genes were MAPK1, SOS1, TGFBR1, TGFBR2, TP53, CASP3, CCNE2, PTEN, and CDK2.

Human Caspase 12 Enhances NF-κB Activity through Activation of IKK in Nasopharyngeal Carcinoma Cells

Human nasopharyngeal carcinoma (NPC) is a highly invasive cancer associated with proinflammation. Caspase-12 (Casp12), an inflammatory caspase, is implicated in the regulation of NF-κB-mediated cellular invasion via the modulation of the IκBα protein in NPC cells. However, the effect mechanisms of Casp12 need to be elucidated. NPC cells were transfected with the full length of human Casp12 cDNA (pC12) and the effect of human Casp12 (hCasp12) on the NF-κB activity was investigated. We found ectopic expression of hCasp12 increased the NF-κB activity accompanied by an increased p-IκBα expression and a decreased IκBα expression. Treatment of BMS, a specific IKK inhibitor, and pC12-transfected cells markedly decreased the NF-κB activity and ameliorated the expression level of IκBα reduced by hCasp12. Co-immunoprecipitation assays validated the physical interaction of hCasp12 with IKKα/β, but not with NEMO. Furthermore, the NF-κB activity of ΔCasp12-Q (a mutated catalytic of hCasp12) transfected cells was concentration-dependently induced, but lower than that of hCasp12-transfected cells. Importantly, the hCasp12-mediated NF-kB activity was enhanced by TNFα stimulation. That indicated a role of the catalytic motif of hCasp12 in the regulation of the NF-κB activity. This study indicated hCasp12 activated the NF-κB pathway through the activation of IKK in human NPC cells.

Caspase 12 degrades IκBα protein and enhances MMP-9 expression in human nasopharyngeal carcinoma cell invasion

Caspase-12 (Casp12), an inflammatory caspase, functions as a dominant-negative regulator of inflammatory responses and is associated with the signaling of apoptosis. However, the physiological function of Casp12 presented in cancer cells is still unclear. This study demonstrated that overexpression of Casp12 mediated IκBα degradation and significantly increased NF-κB activity. Exposure of human nasopharyngeal carcinoma (NPC) cells to phorbol-12-myristate-13-acetate (PMA) increased the levels of Casp12 and MMP-9 resulting in NPC cell invasion. Target suppression of Casp12 by small interfering RNA (siRNA) or an inhibitor of Casp12 markedly decreased the level of PMA-induced MMP-9 protein and cell invasion. Moreover, suppression of Casp12 significantly inhibited the basal activity of NF-κB and decreased the PMA-induced NF-κB reporter activity. The effect of Casp12 on NF-κB activation was indicated via the post-translational degradation of IκB. This study revealed that a critical role of Casp12 on the activation of NF-κB via IκBα degradation which provides a link between inflammatory and aggressive invasion in NPC cells.

Osthole sensitizes with radiotherapy to suppress tumorigenesis of human nasopharyngeal carcinoma in vitro and in vivo

BACKGROUND

Radiotherapy is one of the most comment and useful treatment for nasopharyngeal carcinoma (NPC), but the radioresistance remains a major obstacle. Osthole, a natural coumarin derivative, has been shown to have anti-tumor and anti-inflammatory activity. However, the relationship between osthole and NPC treatment, especially for radiotherapy, is still elusive.

METHODS

Osthole with or without X ray radiotherapy treated with CNE2 cells, a human EC cell line. Cell viability, proliferation, migration and apoptosis were measured by MTT, colony formation, Annexin V/PI double staining, Transwell assay, respectively. NPC tumor models were established on BALB/c nude mice by subcutaneously injection of CNE2 cells and the effect of osthole and radiotherapy on tumor growth in vivo was studied.

RESULTS

We found that in a dose-dependent manner, osthole could individually, and synergistically with radiotherapy, reduce NPC cell (CNE2) viability, proliferation, migration, and invasion, and induce apoptosis, respectively. This effect of anti-tumor growth and induction of apoptosis was further confirmed in mice induced by subcutaneously injection with CNE2 cells and following treated with osthole or/and radiation.

CONCLUSION

Osthole increases the effect of radiotherapy on anti-human nasopharyngeal cancer.

Physcion, a naturally occurring anthraquinone derivative, induces apoptosis and autophagy in human nasopharyngeal carcinoma

AIM

Physcion is a major bioactive ingredient in the traditional Chinese medicine Radix et Rhizoma Rhei, which has an anthraquinone chemical structure and exhibits a variety of pharmacological activities including laxative, hepatoprotective, anti-inflammatory, anti-microbial and anti-proliferative effects. In this study we investigated the effect of physcion on human nasopharyngeal carcinoma in vitro and in vivo, as well as the mechanisms underlying the anti-tumor action.

METHODS

The nasopharyngeal carcinoma cell line CNE2 was treated with physcion, and cell viability was detected using MTT and colony formation assays. Flow cytometry was used to assess the cell cycle arrest, mitochondrial membrane potential loss, apoptosis, autophagy and intracellular ROS generation. Apoptotic cell death was also confirmed by a TUNEL assay. The expression of target or marker molecules was determined using Western blotting. The activity of caspase-3, 8, and 9 was detected with an ELISA kit. A xenograft murine model was used to evaluate the in vivo anti-tumor action of physcion, the mice were administered physcion (10, 20 mg·kg-1·d-1, ip) for 30 d.

RESULTS

Treatment with physcion (5, 10, and 20 μmol/L) dose-dependently suppressed the cell viability and colony formation in CNE2 cells. Physcion (10 and 20 μmol/L) dose-dependently blocked cell cycle progression at G1 phase and induced both caspase-dependent apoptosis and autophagy in CNE2 cells. Furthermore, physcion treatment induced excessive ROS generation in CNE2 cells, and subsequently disrupted the miR-27a/ZBTB10 axis, resulting in repression of the transcription factor Sp1 that was involved in physcion-induced apoptosis and autophagy. Moreover, physcion-induced autophagy acted as a pro-apoptotic factor, and possibly contributed to physcion-induced apoptosis. In the xenograft murine model, administration of physcion dose-dependently suppressed the tumor growth without affecting the body weight. Furthermore, the anti-tumor effects of physcion were correlated with downregulation of Sp1 and suppression of miR-27a in the tumor tissues.

CONCLUSION

Physcion induces apoptosis and autophagy in human nasopharyngeal carcinoma by targeting Sp1, which was mediated by ROS/miR-27a/ZBTB10 signaling. The results suggest that physcion is a promising candidate for the treatment of human nasopharyngeal carcinoma.

Anticancer activities of alkaloids extracted from the Ba lotus seed in human nasopharyngeal carcinoma CNE-1 cells

To investigate the anticancer activities of alkaloids from the Ba lotus seed (BLSA) in human nasopharyngeal carcinoma (NPC) CNE-1 cells, an MTT assay, flow cytometry, reverse transcription-polymerase chain reaction and western blotting were performed. BLSA was found to significantly reduce CNE-1 cell proliferation in a dose-dependent manner at all concentrations compared with the control (P<0.05). In addition, flow cytometry analysis identified that BLSA treatment significantly increased the sub-G1 content in CNE-1 cells (P<0.05). Following BLSA treatment, the mRNA and protein levels of a number of apoptosis-related factors, such as caspase family members (caspase-3, -8 and -9), B-cell lymphoma (Bcl)-2-associated X protein, Fas and Fas ligand were significantly increased compared with the control (P<0.05). This was accompanied by a significant decrease in anti-apoptotic Bcl-2 and Bcl-extra large protein expression compared with the control (P<0.05). Furthermore, BLSA treatment was determined to modulate CNE-1 cell expression of nuclear factor (NF)-κB and NF-κB inhibitor α. The results of the present study indicate that BLSA has anticancer activity through inducing cellular apoptosis. In addition, these results suggest that BLSA can be used as a therapeutic agent in NPC.

Nobiletin inhibits invasion and migration of human nasopharyngeal carcinoma cell lines by involving ERK1/2 and transcriptional inhibition of MMP-2

OBJECTIVE

Nasopharyngeal carcinoma (NPC) is known for its high incidence of neck lymph node metastasis, which represents poor prognosis. Nobiletin is a citrus polymethoxyflavonoid that suppresses tumor growth and metastasis, both of which depend on angiogenesis in previous studies. However, the effect of Nobiletin on human NPC cells metastasis has not been clearly clarified.

RESEARCH DESIGN AND METHODS

In this study, we determine the effects of Nobiletin on the migration and invasion in NPC cells.

RESULTS

Nobiletin significantly inhibited migration/invasion capacities of HONE-1 and NPC-BM cell lines. The results of gelatin zymography and western blotting revealed that the activities and protein levels of the MMP-2 were inhibited by Nobiletin. Nobiletin also showed that inhibits phosphorylation of ERK1/2. Tests of the real-time PCR and promoter assays evaluated the inhibitory effects of Nobiletin on MMP-2 expression in human NPC cells. Nobiletin inhibits MMP-2 expression, up-regulating tissue inhibitor of metalloproteinase-2 and down-regulation of the transcription factors of NF-κB and activator protein 1 (AP-1) signaling pathways. Finally, an administration of Nobiletin effectively suppressed the tumor formation and metastasis in the NPC xenograft model in vivo.

CONCLUSIONS

Nobiletin may have potential use as a chemo-preventive agent against nasopharyngeal cancer metastasis.

PinX1 regulation of telomerase activity and apoptosis in nasopharyngeal carcinoma cells

BACKGROUND

Human interacting protein X1 (PinX1) has been identified as a critical telomerase inhibitor and proposed to be a putative tumor suppressor gene. Loss of PinX1 has been found in a large variety of malignancies, however, its function in inhibiting telomerase activity of tumor cells is not well documented. Here we show that PinX1 is essential for down-regulation telomerase activity of nasopharyngeal carcinoma.

METHODS

Expression vectors of human PinX1 (pEGFP-C3-PinX1) and its small interfering RNA (PinX1-FAM-siRNA) were constructed and transfected into NPC. Their effects on mRNA of telomerase catalytic subunit (hTERT), telomerase activity, cell proliferation, cell migration, wound healing, cell cycles and apoptosis were examined using semi-quantitative RT-PCR, stretch PCR, MTT assay, Transwell, scratch assay and flow cytometry, respectively.

RESULTS

Transfection of pEGFP-C3-PinX1 and PinX1-FAM-siRNA increased and reduced PinX1 mRNA by 1.6-fold and 70%, respectively. Over-expression of PinX1 decreased hTERT mRNA by 21%, reduced telomerase activity, inhibited cell growth, migration and wound healing ability, arrested cells in G0/G1 phase, and increased apoptotic index. In contrast, down-regulation of PinX1 did not alter the above characteristics.

CONCLUSIONS

PinX1 may play important roles in NPC proliferation, migration and apoptosis and has application potential in tumor-targeted gene therapy.