Feedback loop in miR-449b-3p/ADAM17/NF-κB promotes metastasis in nasopharyngeal carcinoma.

An emerging body of evidence has promoted the understanding of the role of microRNAs (miRNAs) in tumorigenesis and progression, but the mediating function of miRNAs in nasopharyngeal carcinoma (NPC) development remains poorly elucidated. In this study, miR-449b-3p was downregulated in NPC specimens (P < .001) and cells (P < .05). Cytological and animal experiments provided evidence that miR-449b-3p inhibited NPC metastasis in vitro and in vivo. Disintegrin and metalloproteinase 17 (ADAM17) was revealed as a direct target of miR-449b-3p. Rescue experiments suggested that the downregulation of ADAM17 in the miR-449b-3p knockdown cells partially reversed the inhibition of cell invasion and migration. Luciferase reporter assay, chromatin immunoprecipitation assay, and Western blot analysis showed that ADAM17 could suppress the promoter activity and expression of miR-449b-3p by inducing NF-κB transcriptional activity. In conclusion, our study provided new insights into the underlying mechanism of the invasion and metastasis of NPC. The novel miR-449b-3p/ADAM17/NF-κB feedback loop could be a target for the clinical treatment of NPC.

MIIP gene expression is associated with radiosensitivity in human nasopharyngeal carcinoma cells.

The present study aims to investigate the radiosensitization effect of the migration and invasion inhibitory protein (MIIP) gene on nasopharyngeal carcinoma (NPC) cells. The MIIP gene was transfected into NPC 5-8F and CNE2 cells. The level of MIIP was analyzed by quantitative reverse transcription-polymerase chain reaction analysis and western blot. The changes in radiosensitivity of the cells were analyzed by colony formation assay. The changes in cell apoptosis and cycle distribution following irradiation were detected by flow cytometry. The expression of BCL2 associated X, apoptosis regulator/B-cell lymphoma 2 was evaluated using western blot. DNA damage was analyzed by counting γ-H2AX foci. The expression levels of γ-H2AX were evaluated by immunofluorescence and western blot. In a previous study by the authors, the results indicated that the expression of MIIP gene evidently increased in MIIP-transfected 5-8F (5-8F OE) and MIIP-transfected CNE2 (CNE2 OE) cells compared with the parental or negative control cells. In the present study, the survival rate of 5-8F OE and CNE2 OE cells markedly decreased following irradiation (0, 2, 4, 6 and 8 Gy) compared with the negative control (5-8F NC and CNE2 NC) and the untreated (5-8F and CNE2) groups. The expression of MIIP was able to increase apoptosis, which resulted in G2/M cell cycle arrest and DNA damage repair was attenuated in 5-8F and CNE2 cells following irradiation as measured by the accumulation of γ-H2AX. It was indicated that MIIP expression is associated with the radiosensitivity of NPC cells and has a significant role in regulating cell radiosensitivity.

MiR-152 functioning as a tumor suppressor that interacts with DNMT1 in nasopharyngeal carcinoma.

BACKGROUND: In recent years, miR-152 has been dysregulated in a variety of tumors and used as a tumor suppressor. Nevertheless, its role in nasopharyngeal carcinoma (NPC) remains unidentified. MATERIALS AND METHODS: Real-time quantitative PCR (polymerase chain reaction) was performed to analyze the expression of miR-152 in NPC cell lines. MiR-152 expression profiles in NPC tissues were obtained from Gene Expression Omnibus (GEO GSE36682). The effect of miR-152 on the invasion and proliferation of NPC cells was determined through cell invasion, wound healing, and cell viability assays. Apoptosis was examined by flow cytometry, and Western blot was performed to measure expression of the target gene. Pyrosequencing was used to detect the methylation level of NPC cells. RESULTS: In this study, miR-152 was downregulated in the NPC tissues and cell lines. When miR-152 was enhanced, the invasion and migration of NPC cells were inhibited. However, miR-152 had no effect on the proliferation of NPC cells. Luciferase reporter gene analysis was performed, and the results showed that DNMT1 (DNA (cytosine-5)-methyltransferase 1) is a direct target of miR-152 in NPC cells. DNMT1 downregulation and miR-152 overexpression both reversed the effects of miR-152 inhibition on the NPC cells. In addition, miR-152 expression increased as a result of the inhibition of the methylation level of miR-152 when DNMT1 expression was downregulated. CONCLUSION: The overexpression of miR-152 inhibited the migration and invasion of NPC cells by targeting DNMT1. Furthermore, DNMT1 regulated miR-152 expression through DNA methylation. Overall, the novel miR-152-DNMT1 regulatory circuit may provide better understanding of the pathogenesis of NPC and new epigenetic therapeutic target in NPC.

Long non-coding RNA n326322 promotes the proliferation and invasion in nasopharyngeal carcinoma.

Long non-coding RNAs (lncRNAs) have been reported to perform significant roles in cancer development and progression. Our research has found that a novel lncRNA n326322 was higher in nasopharyngeal carcinoma (NPC) cells. Moreover, the gain and loss of functional approaches revealed that the overexpression of lncRNA-n326322 promoted NPC cell proliferation and invasion, whereas the downregulation of lncRNA-n326322 suppressed cell proliferation and invasion. Further experiments demonstrated that potential mechanism may be associated with the activation of PI3K/AKT and ERK/MAPK pathways. Taken together, these results indicate that lncRNA-n326322 is associated with tumorigenesis of NPC.

MicroRNA-19b-3p regulates nasopharyngeal carcinoma radiosensitivity by targeting TNFAIP3/NF-κB axis.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is among the most common squamous cell carcinoma in South China and Southeast Asia. Radiotherapy is the primary treatment for NPC. However, radioresistance acts as a significant factor that limits the efficacy of radiotherapy for NPC patients. Growing evidence supports that microRNAs (miRNAs) play an important role in radiation response. METHODS: Real-time quantitative PCR was used to analyze the expression of miR-19b-3p in NPC cell lines and NP69. miR-19b-3p expression profiles in NPC tissues were obtained from the Gene Expression Omnibus database. The effect of miR-19b-3p on radiosensitivity was evaluated by cell viability assays, colony formation assays and in vivo experiment. Apoptosis and cell cycle were examined by flow cytometry. Luciferase reporter assay was used to assess the target genes of miR-19b-3p. Expression of target proteins and downstream molecules were analyzed by Western blot. RESULTS: miR-19b-3p was upregulated in NPC and served as an independent predictor for reduced patient survival. Radioresponse assays showed that miR-19b-3p overexpression resulted in decreased sensitivity to irradiation, whereas miR-19b-3p downregulation resulted in increased sensitivity to irradiation in vitro. Moreover, miR-19b-3p decreased the sensitivity of NPC cells to irradiation in vivo. Luciferase reporter assay confirmed that TNFAIP3 was a direct target gene of miR-19b-3p. Knockdown of TNFAIP3 reduced sensitivity to irradiation, whereas upregulation of TNFAIP3 expression reversed the inhibitory effects of miR-19b-3p on NPC cell radiosensitivity. Mechanistically, we found that miR-19b-3p increased NPC cell radioresistance by activating the TNFAIP3/ NF-κB axis. CONCLUSIONS: miR-19b-3p contributes to the radioresistance of NPC by activating the TNFAIP3/ NF-κB axis. miR-19b-3p is a determinant of NPC radioresponse and may serve as a potential therapeutic target in NPC treatment.

Long-Term Results of Concurrent Chemoradiotherapy for Advanced N2-3 Stage Nasopharyngeal Carcinoma.

BACKGROUND: N-stage is related to distant metastasis in nasopharyngeal carcinoma (NPC) patients. The purpose of this study was to evaluate the efficacy and toxicity of different nedaplatin-based chemotherapy regimens in advanced N2-3 stage NPC patients treated with intensity modulated radiation therapy (IMRT). PATIENTS AND METHODS: Between April 2005 and December 2009, a total of 128 patients with N2-3 advanced NPC were retrospectively analyzed. Patients were treated with IMRT concurrent with 2 cycles of chemotherapy consisting of either nedaplatin plus paclitaxel (NP group, n = 67) or nedaplatin plus fluorouracil and paclitaxel (NFP group, n = 61). Two to four cycles of adjuvant chemotherapy were then administered every 21 days following concurrent chemoradiotherapy. RESULTS: With a median follow-up of 60 months, the 5-year overall survival (OS), progression-free survival (PFS), local-regional recurrence-free survival (LRRFS), and distant metastasis-free survival (DMFS) for all patients were 81.4%, 71.5%, 87.8% and 82.0%, respectively. No significant difference in PFS (66.6% vs. 76.7%, P = 0.212) and LRRFS rates (89.0% vs. 86.3%, P = 0.664) was observed between the NP and NFP groups. The 5-year OS (75.4% vs. 88.5%, P = 0.046) and DMFS (75.1% vs. 89.0%, P = 0.042) rate were superior in the NFP group compared with the NP group. The NFP group had a higher incidence of grade 3-4 acute toxicities including bone marrow suppression (leukopenia: χ2 = 3.935, P = 0.047; anemia: χ2 = 9.760, P = 0.002; thrombocytopenia: χ2 = 8.821, P = 0.003), and both liver and renal dysfunction (χ2 = 5.206, P = 0.023) compared with the NP group. Late toxicities were moderate and no difference was observed between the two groups. CONCLUSION: IMRT concurrent with nedaplatin-based chemotherapy is an advocated regimen for patients with advanced N2-3 stage NPC. Patients with advanced N2-3 stage may be better candidates for the NFP regimen although this regimen was associated with a high acute toxicity rate.

MiR-145, a microRNA targeting ADAM17, inhibits the invasion and migration of nasopharyngeal carcinoma cells.

MiR-145 is downregulated and functions as a tumor suppressor in many malignancies. In this study, the biological function, molecular mechanism, and direct target genes of miR-145 in nasopharyngeal carcinoma (NPC) cells were investigated. Cell survival was detected by cell viability assay, and cell cycle was determined through flow cytometry. Invasion and migration of NPC cells were examined using cell invasion and wound healing assays, respectively. A disintegrin and metalloproteinase 17 (ADAM17) was verified as the target of miR-145 through luciferase reporter assay, qRT-PCR, and Western blot analysis. In NPC cell lines, miR-145 expression was significantly downregulated and ADAM17 protein expression was upregulated. ADAM17 was downregulated at the post-transcriptional level by miR-145 via the binding site of ADAM17-3'UTR. Transfection with miR-145 mimic suppressed cell growth and induced cell cycle arrest in the G0/G1 phase by upregulating key G0/G1 phase regulators, namely, p53 and p21. MiR-145 also inhibited cellular migration and invasion through targeting ADAM17 involving the regulation of EGFR and E-cadherin. Knockdown of ADAM17 elicited similar effects to that of miR-145 on NPC cells. This study reveals that miR-145 suppressed the invasion and migration of NPC cells by targeting ADAM17. Thus, miR-145 could be a therapeutic target for NPC.

Impact of plasma Epstein-Barr virus-DNA and tumor volume on prognosis of locally advanced nasopharyngeal carcinoma.

This retrospective study aims to examine the association of plasma Epstein-Barr virus- (EBV-) DNA levels with the tumor volume and prognosis in patients with locally advanced nasopharyngeal carcinoma (NPC). A total of 165 patients with newly diagnosed locally advanced NPC were identified from September 2011 to July 2012. EBV-DNA was detected using fluorescence quantitative polymerase chain reaction (PCR) amplification. The tumor volume was calculated by the systematic summation method of computer software. The median copy number of plasma EBV-DNA before treatment was 3790 copies/mL. The median gross tumor volume of the primary nasopharyngeal tumor (GTVnx), the lymph node lesions (GTVnd), and the total GTV before treatment were 72.46, 23.26, and 106.25 cm(3), respectively; the EBV-DNA levels were significantly correlated with the GTVnd and the total GTV (P < 0.01). The 2-year overall survival (OS) rates in patients with positive and negative pretreatment plasma EBV-DNA were 100% and 98.4% (P = 1.000), and the disease-free survival (DFS) rates were 94.4% and 80.8% (P = 0.044), respectively. These results indicate that high pretreatment plasma EBV-DNA levels in patients with locally advanced NPC are associated with the degree of lymph node metastasis, tumor burden, and poor prognosis.