BackgroundThe spontaneous IL-8 secretion observed in OSCC is partially dependent on the disregulated activity of transcription factor NF-κB. Nickel compounds are well established human carcinogens, however, little is known about the influence of nickel on the spontaneous secretion of IL-8 in oral squamous cell carcinoma (OSCC) cells. The aim of the present study was to investigate whether Ni2+ ions can influence on IL-8 secretion by OSCC.Methods and ResultsThe IL-8 secretion was measured by ELISA. The expression of IL-8 mRNA was examined by real-time PCR. The NF-κB activity was measured by luciferase assay. The phosphorylation status and nuclear localization of NF-κB subunits were examined by Western blotting or Transfactor kit and immunofluorescence staining, respectively. The interaction of NF-κB p50 subunit and Ni2+ ions was examined by Ni2+-column pull down assay. The site-directed mutagenesis was used to generate a series of p50 mutants. Scratch motility assay was used to monitor the cell mobility. Our results demonstrated that, on the contrary to our expectations, Ni2+ ions inhibited the spontaneous secretion of IL-8. As IL-8 reduction was observed in a transcriptional level, we performed the luciferase assay and the data indicated that Ni2+ ions reduced the NF-κB activity. Measurement of p50 subunit in the nucleus and the immunofluorescence staining revealed that the inhibitory effect of Ni2+ ions was attributed to the prevention of p50 subunit accumulation to the nucleus. By Ni2+-column pull down assay, Ni2+ ions were shown to interact directly with His cluster in the N-terminus of p50 subunit. The inhibitory effect of Ni2+ ions was reverted in the transfectant expressing the His cluster-deleted p50 mutant. Moreover, Ni2+ ions inhibited the OSCC mobility in a dose dependent fashion.ConclusionsTaken together, inhibition of NF-κB activity by Ni2+ ion might be a novel therapeutic strategy for the treatment of oral cancer.

The improved survival by the addition of cetuximab is likely to be attributable to the antiepithelial-mesenchymal transition action of cetuximab via inhibiting EGFR-GEP100-Arf6-AMAP1 pathway. © 2016 Wiley Periodicals, Inc. Head Neck 39: 476-485, 2017.

The effect of NiCl2 on oral squamous cell carcinoma-derived cell line HSC3 was examined. Incubation with 1 mM NiCl2 significantly reduced the expression of MMPs at mRNA and protein levels. The in vivo orthotopic implantation model was established by injecting highly metastatic subcell line HSC3-M3 to nude mouse tongue. After 1 week of injection, mice were fed with or without 1 mM NiCl2-containing water for two to three weeks. Immunohistochamical examination revealed that MMP9 expression was drastically reduced in NiCl2-fed mice. By CT images, cancer mass was observed as a translucent area in control mice. In NiCl2-fed mice, much highly translucent area was observed within the translucent area. Histologically, this area corresponded to the necrotic area in the tumor mass. Real-time PCR analysis revealed the reduced expression of angiogenic factors such as IL-8 and VEGF mRNA in NiCl2-fed mice. To further examine the effect of NiCl2 on metastasis, human β-globin gene expression in regional lymphnodes was compared. The β-globin gene was totaly absent in NiCl2-fed mice. Moreover, various cancer metastasis-related genes were inhibited in NiCl2-fed mice by PCR array analysis. The results indicated that NiCl2 might be a promising new anti-cancer therapeutics for the oral cancer treatment.