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.

MicroRNA-21 depletion by CRISPR/Cas9 in CNE2 nasopharyngeal cells hinders proliferation and induces apoptosis by targeting the PI3K/AKT/MOTOR signaling pathway

BACKGROUND

We assess the effects exerted by CRISPR/Cas9 mediated microRNA 21 (miR-21) depletion on the biologic characteristics of CNE2 nasopharyngeal carcinoma (NPC) cells and the underlying mechanisms.

METHODS

The sgRNA was designed targeted at miR-21 gene, along with the construction of the CRISPR/Cas9 lentivirus system and the detection of editing efficiency through T7EN1 enzyme digestion. Effects of miR-21 depletion on the biologic characteristics of CNE2 cells were detected through CCK-8, Transwell Invasion Assay and flow cytometry. Mechanistic studies were based on bioinformatic analysis and immunoblotting.

RESULTS

A CRISPR/Cas9 system with targeted knockdown of miR-21 gene was obtained. miR-21 depletion evidently inhibited the growth, clone formation, and invasion as well as migration abilities of CNE2 cells, thus inducing apoptosis. A total of 28 KEGG were identified through the bioinformatic analysis. Further immunoblotting showed that the expressions of proteins involved in the PI3K/AKT/mTOR signaling pathway were decreased in response to miR-21 depletion.

CONCLUSIONS

miR-21 depletion can suppress the cell growth as well as proliferation and induce apoptosis in CNE2 cells possibly by inhibiting the PI3K/AKT/mTOR signaling pathway.

SERPINB2 overexpression inhibited cell proliferation, invasion and migration, led to G2/M arrest, and increased radiosensitivity in nasopharyngeal carcinoma cells

The aim of this study was to evaluate the effect of SERPINB2 on cell proliferation, cell cycle, epithelial-mesenchymal transition (EMT), invasion, migration, and radiosensitivity in nasopharyngeal carcinoma cells. Both CNE2R and CNE2 cells were transfected with pEGFP-N1-SERPINB2. Cell proliferation was measured by MTT assay, cell cycle by flow cytometry, and SERpINB2 expression by quantitative real-time polymerase chain reaction (qRT-PCR). Western blot was carried out to detect the protein expression. In addition, SERPINB2 and β-catenin were located intracellularly using an immunofluorescent assay, and cell migration and invasion were measured by wound healing and Transwell assays, respectively. Radiosensitivity was assessed using colony formation and MTT assays. SERPINB2 expression was downregulated in CNE2R cells. After transfection with pEGFP-N1-SERPINB2, the OD values were decreased, and there was an increased fraction in the G2/M phase. Moreover, SERPINB2 overexpression could inhibit the invasion and migration capabilities of CNE2R and CNE2 cells, with downregulation of vimentin, N-cadherin, nuclear β-catenin, matrix metalloproteinase (MMP)-2 and MMP-9, and upregulation of E-cadherin. Moreover, transfection with the SERPINB2 plasmid reduced the growth rate of CNE2R cells at doses of 2, 4 and 6 Gy, and also decreased the surviving fractions. Overexpression of SERPINB2 could reduce the proliferation, invasion and migration capabilities of CNE2R and CNE2 cells, and led to G2/M arrest via EMT inhibition, and this may be a potential strategy for enhancing the radiation sensitivity of nasopharyngeal carcinoma cells.

Triptolide inhibits cell growth and GRP78 protein expression but induces cell apoptosis in original and radioresistant NPC cells

The radioresistance is the key factor to hamper curative effect and survival of nasopharyngeal carcinoma (NPC) patients. Nature triptolide (TPL) has been found to circumvent drug-resistant effect of cancer, but its effect on NPC radioresistance has been rarely studied. In the present study, the 10 Gy-resistant CNE2 subclones (CNE2-SR) were used as a NPC radioresistant model. The IC₅₀ of TPL in CNE2 and CNE2-SR cells was measured by MTT assay, cell cycle was analyzed by flow cytometry, and protein expression was examined by western blot. Our data showed that TPL treatment decreased the percentage of viable cells, and IC50 value in CNE2 and CNE2-SR cells was 23.6 ± 1.41 nmol/L and 31.2 ± 1.16 nmol/L, respectively. Six Gy was a moderate dosage of X-ray for CNE2, and 25 nM TPL was close to IC50 value of CNE2 and CNE2-SR. Six Gy X-ray and/or 25 nM TPL significantly inhibited tumor growth in nude mice. Furthermore, 6 Gy X-ray and/or 25 nM TPL significantly inhibited cell growth and induced cell apoptosis and M/G2 phase arrest in CNE2 and CNE2-SR cells. Moreover, TPL treatment significantly inhibited the expression of GRP78 protein in CNE2 and CNE2-SR cells. These results suggest that TPL may serve as a potential radiosensitizer agent for NPC treatment.

Exogenous WWOX enhances apoptosis and weakens metastasis in CNE2 nasopharyngeal carcinoma cells through the intrinsic apoptotic pathway

The WW domain containing oxidoreductase (WWOX) has been postulated to behave as a putative tumor suppressor and that silencing of WWOX expression is linked to the carcinogenesis and progression of various carcinomas. The role of WWOX in nasopharyngeal carcinoma (NPC) remains unclear. Herein, we sought to evaluate the biological feature of WWOX restoration in human CNE2 NPC cells. In vitro experiments manifested that transiently overexpressed WWOX significantly suppressed proliferation as well as invasion and migration of the CNE2 cells. Of note, WWOX-induced apoptosis could be partly reversed by the selective caspase inhibitor, Z-VAD-FMK. Furthermore, immunoblotting analysis indicated that ectopic expression of WWOX could trigger the intrinsic apoptotic signaling pathway characterized by a down-regulation of Bcl-2 and Bcl-xL, and up-regulation of Bax and Cytochrome c along with a remarkable activation of the caspase cascades. Taken together, our data reveal that WWOX behaves as a potent tumor suppressor in CNE2 cells, possibly by enhancing apoptosis and weakening metastasis via the intrinsic apoptotic pathway.

Dasatinib suppresses invasion and induces apoptosis in nasopharyngeal carcinoma

Dasatinib, an orally available tyrosine kinas inhibitor (TKI), potently inhibits SRC which was found to activate RTKs that induce trastuzumab de novo and acquired resistance. To evaluate the potential of Dasatinib in the treatment of Nasopharyngeal Carcinoma, we used a variety of assays to measure its effects on cell proliferation, apoptosis, and migration. This work aimed to test the antitumor effects of the inhibitor in vitro to determine whether in vivo analyses were warranted. Cell growth rate and 50% inhibitory concentration was calculated by MTT assay. Dasatinib-induced apoptotic cells were investigated by Annexin V/PI staining. Proteins from cell extracts were analyzed by Western blot. Cell motility was investigated by Transwell. Our study showed that Dasatinib significantly inhibited CNE2 proliferation and induced apoptosis in vitro. Phospho-AKT, phospho-MEK, phospho-ERK expression was significantly reduced when treated with dasatinib which means the downregulated RAS/RAF/MEK/ERK and PI3K/AKT pathway activity. Dasatinib significantly inhibited the motility of CNE2 as well as Phospho-FAK expression. Dasatinib exhibit antitumor effects of nasopharyngeal carcinoma by downregulating MAPK and PI3K/AKT pathways activity and FAK phosphorylation. This suggests that dasatinib would have therapeutic activity against NPC.