Nickel ion inhibits nuclear factor-kappa B activity in human oral squamous cell carcinoma

Correlation between Metal Ions and Cytokines in the Saliva of Patients with Oral Lichenoid Lesions

PURPOSE

We aimed to investigate the effect of metal ions from oral prostheses (OPs) released into the saliva of patients with oral lichenoid lesions (OLLs).

MATERIALS AND METHODS

Subjects (n=183) were divided into four groups according to the presence or absence of OLL and OP. Concentrations of the metal ions titanium, chromium (Cr), cobalt (Co), nickel (Ni), palladium (Pd), silver (Ag), platinum (Pt), gold (Au), and zirconium (Zr) were measured using a laser-ablation microprobe inductively coupled to a plasma mass spectrometer. Saliva levels of interleukin (IL)-6, IL-1β, IL-8, and tumor necrosis factor-α were detected using an enzyme-linked immunosorbent assay. The reticulation/keratosis, erythema, and ulceration (REU) scoring system was used to assess the severity of OLL.

RESULTS

Mean concentrations of IL-6 and IL-8 were statistically higher in OLL patients with OPs. The concentration of Ni was high in OLL groups. The concentrations of Cr, Ni, and Au ions in the saliva were positively correlated with IL-8. REU scores were positively correlated with salivary concentrations of IL-6 and IL-8, as well as with concentrations of Cr, Ni, and Au.

CONCLUSION

Increased concentrations of metal ions, especially Ni, in saliva were positively correlated with IL-8 and showed positive correlations with the severity of OLL.

JunB can enhance the transcription of IL-8 in oral squamous cell carcinoma

Proteasome inhibitor MG132 was shown to enhance the secretion of interleukin 8 (IL-8) by various cells. The enhancement is regulated by the transcription factor activator protein-1 (AP-1) at the transcriptional level. AP-1 is a dimer formed by AP-1 family proteins. The purpose of the present study was to explore the combinations of the AP-1 family proteins that contribute to MG132-driven IL-8 secretion. Oral squamous cell carcinoma-derived cell lines, Ca9-22 and HSC3, were used to demonstrate their response to MG132. IL-8 secretion was augmented by MG132 in both cell lines. c-Jun expression was detected in both the cell lines, whereas c-Fos expression was detected only in the HSC3. The influence of MG132 stimulation on c-Jun and c-Fos expression was further examined by western blot analysis. c-Jun expression was increased by MG132 stimulation, whereas c-Fos expression was not detected even after MG132 stimulation. As JunB is reported to inhibit the transcriptional activity of the AP-1 complex, we speculated that the c-Jun homodimer should contribute to IL-8 enhancement. Expression vectors encoding wild type and c-Jun mutants, M17 and M22-23, respectively, were constructed and transfected into the Ca9-22 cells. In contrast to our expectations, MG132-induced IL-8 secretion was significantly reduced in all the transfectants suggesting that other c-Jun members might form homodimers with c-Jun and contribute to IL-8 enhancement. Transfection of the cells with c-Jun or JunB small hairpin RNA (shRNA) reduced IL-8 secretion up to 50% and 65% of the control shRNA transfectant. Furthermore, cotransfection of both shRNA almost completely inhibited the IL-8 secretion. These results indicate that JunB not only inhibits but also enhances the transcription of c-Jun targets in combination with c-Jun.

A static magnetic field inhibits the expression of platelet-derived growth factor-AA in human oral squamous cell carcinoma

Magnetic attachments are commonly used for overdentures. The deleterious effects of exposure to magnetic flux on human health have not been substantiated so far; nevertheless, there is a need to understand the extent of magnetic field exposure in the oral area resulting from the use of magnetic attachments. The purpose of this study was to investigate the influence of a magnetic field on oral squamous cell carcinoma. Tumor cells cultured on a magnetic plate were compared with those not cultured on a magnetic plate (controls). The cells were seeded at a density of 1 × 10⁵ cells/well and cultured for 6 days. The influence of the magnetic field on cytokine production was examined by cytokine array analysis. Secretion of platelet-derived growth factor-AA (PDGF-AA) was measured by enzyme-linked immunosorbent assay and Western blotting. The expression of PDGF-AA messenger RNA was examined by real-time polymerase chain reaction, whereas nuclear factor-kappa B activity was measured by luciferase assay. The results indicated that the magnetic field inhibited the secretion of PDGF-AA, thereby inhibiting PDGF-AA-induced expression, thus reducing the risk of cancer recurrence.

Nickel chloride administration prevents the growth of oral squamous cell carcinoma

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.

The role of the PM2.5-associated metals in pathogenesis of child Mycoplasma Pneumoniae infections: a systematic review

The peak occurrence of Mycoplasma pneumoniae (M. pneumoniae) infections in childhood and haze episodes is concurrent. Together, the prevalence of macrolide-resistant M. pneumoniae varies among countries might also be related to the concentration of ambient fine particulate mass (aerodynamic diameter ≤2.5 μm, PM2.5). Numerous cohort studies have identified consistent associations between ambient PM2.5 and cardiorespiratory morbidity and mortality. PM2.5 is a carrier of the heavy metals. The relationship between PM2.5-associated metals and M. pneumoniae infections in childhood has been increasingly drawing public attention. First, we reviewed original articles and review papers in Pubmed and Web of Science regarding M. pneumoniae and PM2.5-associated metal and analyzed the structural basis of PM2.5-associated metal interaction with M. pneumoniae. Then, the possible mechanisms of action between them were conjectured. Mechanisms of oxidative stress induction and modulation of the host immune system and inflammatory responses via Toll-like receptors (TLRs) and/or the nuclear factor-kappa B (NF-κB) pathway are postulated to be the result of PM2.5-associated metal complex interaction with M. pneumoniae. In addition, a heavy metal effect on M. pneumoniae-expressed community-acquired respiratory distress syndrome (CARDS) toxin, and activation of the aryl hydrocarbon receptor (AhR) and TLRs to induce the differentiation of T helper (Th) cells are also regarded as important reasons for the influence of the heavy metals on the severity of M. pneumoniae pneumonia and the initial onset and exacerbation of M. pneumoniae associated asthma. PM2.5-associated metals via complex mechanisms can exert a great impact on the host through interaction with M. pneumoniae.

Nicotine-Mediated Ca(2+)-Influx Induces IL-8 Secretion in Oral Squamous Cell Carcinoma Cell

Cigarette smoking is one of the most important risk factors for the development of various diseases. Nicotine is the most extensively investigated component of cigarette smoke, and a comprehensive analysis of the genes induced by nicotine stimulation revealed that interleukin-8 (IL-8) was induced in oral squamous cell carcinoma cell (OSCC). Based on this background, the signaling mechanisms of nicotine-mediated IL-8 induction in OSCC was investigated. Augmented IL-8 secretion by Ca9-22 cells was blocked by the NF-κB inhibitor L-1-4'-tosylamino-phenylethyl-chloromethyl ketone (TPCK) and the nicotinic acetylcholine receptor (nAChR)-specific inhibitor α-bungarotoxin (αBtx). The downstream signaling pathway was further examined by pre-incubating the cells with inhibitors against mitogen-activated protein kinase (MEK), protein kinase C (PKC), and Ca(2+)/calmodulin-dependent kinase II (CaMK II). Only the CaMK II inhibitor was found to exert an inhibitory effect on nicotine-mediated IL-8 secretion. Pre-treatment of the Ca9-22 cells with the Ca(2+) chelator BAPTA-AM drastically inhibited IL-8 secretion. Although nicotine stimulation induced the phosphorylation of the NF-κB p65 subunit, pre-treatment with BAPTA-AM was found to inhibit this activity significantly. CaMK II-dependent p65 phosphorylation was confirmed by pre-incubation of the cells with CaMK II inhibitor. The results from this study indicate that the binding of nicotine to nAChR induces Ca(2+) influx, which results in the activation and phosphorylation of CaMK II and NF-κB p65, respectively. Nicotine-mediated IL-8 induction should be a trigger for the initiation of various diseases.

Cancer cell-derived IL-8 induces monocytic THP1 cells to secrete IL-8 via the mitogen-activated protein kinase pathway

Aberrant activity of transcription factors in oral squamous cell carcinoma (OSCC) results in the spontaneous secretion of various cytokines and chemokines. Among them, IL-8, owing to its angiogenic activity, promotes the growth of OSCCs. In the present study, we examined the role of IL-8 secreted by OSCCs, on the angiogenic activity of monocytic THP1 cells. Culture supernatant (Ca-sup) augmented IL-8 secretion by THP1 cells, which was found to be significantly reduced following the removal Ca9-22-derived IL-8 from the Ca-sup. IL-8 induction was regulated at the transcriptional level, because real-time PCR demonstrated the augmented IL-8 messenger RNA (mRNA) expression. We further performed the luciferase assay using the 5'-untranslated region of IL-8 gene. Contradictory to our speculations, luciferase activity was not augmented by Ca-sup stimulation. NF-κB-independent IL-8 induction was further confirmed by pre-treating THP1 cells with NF-κB-specific inhibitors. To elucidate the signaling pathway, THP1 was pre-treated with MEK inhibitors. The results demonstrated that pre-treatment of cells with MEK inhibitor drastically reduced IL-8 levels, suggesting the role of MEK. Moreover, Ca-sup was found to increase ERK1/2 phosphorylation in a time-dependent manner. These results indicated that OSCC-derived IL-8 appears to activate angiogenic activity in monocytes within the tumor microenvironment via the mitogen-activated protein kinase (MAPK) pathway.

Nickel ions selectively inhibit lipopolysaccharide-induced interleukin-6 production by decreasing its mRNA stability

Nickel (Ni) ions easily elute from many alloys and elicit inflammation and allergies. Previous studies have shown that infections due to the implantation of medical devices cause inflammation and enhance the elution of Ni ions (Ni²⁺). However, cross-talk between infection- and Ni²⁺-induced signaling pathways has not yet been elucidated in detail. In the present study, we investigated the effects of Ni2+ on the lipopolysaccharide (LPS)-induced production of cytokines in a LPS-induced air pouch-type inflammation model in BALB/c mice and the murine macrophage cell line RAW264. We demonstrated that Ni²⁺ inhibited the LPS-induced production of interleukin (IL)-6, but not that of tumor necrosis factor (TNF)-α both in vivo and in vitro. This inhibitory effect was also observed with cobalt ion (Co²⁺), but not with chloride ion (Cl⁻), zinc ion (Zn²⁺), or palladium ion (Pd²⁺), and was highly selective to the production of IL-6. Ni²⁺ did not inhibit the activation of ERK1/2, p38 MAPK, or JNK. Although Ni²⁺ decreased IL-6 mRNA levels, it failed to inhibit the LPS-induced activation of the IL-6 promoter. An experiment using actinomycin D, a transcription inhibitor, revealed that Ni²⁺ decreased the stability of IL-6 mRNA. Moreover, Ni²⁺ inhibited the LPS-induced expression of Arid5a, but not regnase-1. These results demonstrated that Ni²⁺ may have selectively inhibited the LPS-induced production of IL-6 by decreasing the Arid5a-dependent stabilization of IL-6 mRNA.