Toxic Metals Increase Serum Tumor Necrosis Factor-α Levels, Modified by Essential Elements and Different Types of Tumor Necrosis Factor-α Promoter Single-nucleotide Polymorphisms.

BACKGROUND: Lead (Pb), cadmium (Cd), and arsenic (As) could cause health issues through oxidative stress that is indicated in the elevated tumor necrosis factor-alpha (TNF-α). However, some of the essential elements-selenium (Se), zinc (Zn), cobalt (Co), and copper (Cu)-are cofactors or structural components of antioxidant enzymes. It is suggested that single-nucleotide polymorphisms (SNPs) in the TNF-α gene have different TNF-α responses. This study aims to evaluate the effect of serum TNF-α levels through the interactions between toxic metals and essential elements and how the interactions between the toxic metals and TNF-α SNPs (-1031 T > C, -863 C > A, -857 C > T, -308 G > A, -238 G > A) influence serum TNF-α levels. METHODS: Blood samples were collected from 455 workers who carried out annual health examinations and multielements determined by inductively coupled plasma mass spectrometry (ICP-MS). TNF-α levels were detected by enzyme-linked immunosorbent assay (ELISA). TNF-α promoter SNPs were analyzed by specific primer probes using real-time polymerase chain reaction (PCR) methods. RESULTS: Increasing blood Pb, Cd, and As levels were associated with elevated TNF-α levels. The interaction between Pb and Cu decreased TNF-α levels and so did the interaction between Cd and Se. In the interaction between Pb and SNPs, individuals with AA/AG (-308 G > A) and AA/AG (-238 G > A) had higher serum TNF-α levels. However, lower TNF-α levels were noted in those individuals with AA/CA (-863 C > A). In the interaction between As and SNPs, workers with AA/AG (-238 G > A) had synergic effect with As and induced higher serum TNF-α levels. CONCLUSIONS: Blood Cu and Se were antagonists of toxic metals (Pb, As, and Cd) through lower serum TNF-α levels. Variant types of TNF-α SNPs (-308 G > A, -238 G > A) and wild type of -863 CC would be more susceptible to toxic metals.

Inhibition of Epstein-Barr virus reactivation in nasopharyngeal carcinoma cells by dietary sulforaphane.

Epstein-Barr virus (EBV) has been associated with several human malignancies including nasopharyngeal carcinoma (NPC). Reactivation of latent EBV has been considered to contribute to the carcinogenesis of NPC. Blocking the EBV lytic cycle has been shown effective in the treatment of EBV-associated diseases. We have searched for natural dietary compounds inhibiting EBV reactivation in NPC cells. Among them, sulforaphane (SFN) was found to be effective in the inhibition of EBV reactivation in latent EBV-positive NPC cells, NA and HA. SFN is a histone deacetylase (HDAC) inhibitor and has been recognized as an antioxidant and antitumor compound for chemoprevention. However, its antiviral effect is less well elucidated. In this study, after determination of the cytotoxicity of SFN on various epithelial cells, we showed that SFN treatment inhibits EBV reactivation, rather than induction, by detection of EBV lytic gene expression in EBV-positive NPC cells. We also determined that the number of cells supporting the EBV lytic cycle is decreased using immunofluorescence and flow cytometric analysis. Moreover, we have found that this inhibitory effect decreases virus production. To elucidate the inhibitory mechanism of SFN on the EBV lytic cycle, luciferase reporter assays were carried out on the Zta and Rta promoters. The results show that SFN inhibits transactivation activity of the EBV immediate-early gene Rta but not Zta. Together, our results suggest that SFN has the capability to inhibit EBV lytic cycle and the potential to be taken as a dietary compound for prevention of EBV reactivation.