High levels of autoantibodies against catalase and superoxide dismutase in nasopharyngeal carcinoma

Development and Validation of a Novel Diagnostic Nomogram Model Using Serum Oxidative Stress Markers and AURKA for Prediction of Nasopharyngeal Carcinoma

Purpose

The mortality rate of nasopharyngeal carcinoma (NPC) remains high due to the absence of quick and accurate diagnostic approaches at its early stage. Our aim is to evaluate the diagnostic value of the elevated expression of Aurora kinase A (AURKA) and the oxidative stress markers (such as glutathione, superoxide dismutase and malondialdehyde) in serum of NPC patients and to establish a nomogram model for predicting NPC on the ground of these biomarkers.

Patients and Methods

Serum samples from 93 NPC patients and 94 healthy subjects were collected. Enzyme-linked immunosorbent assay (ELISA) was adopted to determine the AURKA level, while oxidative stress markers were measured by commercially available appropriate kits. Logistic regression was used for NPC predictor identification and nomogram construction. The training and validation cohorts (3:1) were randomly split up from the participants. Receiver operating characteristic (ROC) curves, calibration curves, and decision curve analyses (DCAs) were performed to validate the nomogram.

Results

AURKA and malondialdehyde (MDA) levels were significantly high in the NPC population compared to the healthy controls (P < 0.0001). The nomogram resulted in an area under the curve (AUC) of 0.897 (95% confidence interval: 0.848-0.947) in the training set and AUC of 0.770 (0.628-0.912) in the validation set. The predicted probability and the actual probability matched well in the nomogram (P > 0.05). DCAs showed good results too.

Conclusion

Serum levels of AURKA, SOD, and MDA have diagnostic values in NPC. The nomogram based on the identified biomarkers is favorable for NPC prediction.

Lipid peroxidation, proteins modifications, anti-oxidant enzymes activities and selenium deficiency in the plasma of hashitoxicosis patients

OBJECTIVES

The aim of this study was to explore the oxidative stress profile in hashitoxicosis (HTX) and to compare it with that of healthy subjects.

PATIENTS AND METHODS

Spectrophotometric methods were used to evaluate the oxidative stress markers. The selenium level was investigated by atomic absorption.

RESULTS

High levels of thiobarbituric acid reactive species (TBARS) and conjugated dienes were found in HTX patients (p = 0.034 and p = 0.043, respectively) compared with healthy controls. For antioxidant enzymes, superoxide dismutase (SOD) and catalase activities increased, whereas that of glutathione peroxidase (GPx) decreased (p = 0.000, p = 0.014, p = 0.000, respectively) compared with controls. A reduction in the level of selenium (p = 0.029) and thiol groups (p = 0.008) were shown in patients; however, levels of carbonyl group and malondialdehyde (MDA) protein adducts decreased (p = 0.000) compared with controls. Positive correlation was shown between levels of free thyroxine (FT4) and TBARS (r = 0.711, p = 0.048) and between FT4 level and SOD activity (r = 0.713, p = 0.047). Conversely, GPx activity presented a negative correlation with FT4 and free triiodothyronine (FT3) levels (r = -0.934, p = 0.001; r = -0.993, p = 0.000, respectively). In addition, GPx activity showed positive correlation with selenium level (r = 0.981, p = 0.019) and the FT3 level correlated negatively with the level of thiol groups (r = -0.892, p = 0.017).

CONCLUSIONS

This study shows the presence of an oxidative stress and selenium deficiency in HTX patients and suggests that the hyperthyroid state is strongly implicated in the establishment of this disturbed oxidative profile.

Changes in the nasopharyngeal carcinoma nuclear proteome induced by the EBNA1 protein of Epstein-Barr virus reveal potential roles for EBNA1 in metastasis and oxidative stress responses

Epstein-Barr virus (EBV) infection is causatively associated with a variety of human cancers, including nasopharyngeal carcinoma (NPC). The only viral nuclear protein expressed in NPC is EBNA1, which can alter cellular properties in ways that may promote oncogenesis. Here, we used 2-dimensional difference gel electrophoresis (2-D DiGE) to profile changes in the nuclear proteome that occur after stable expression of EBNA1 in the EBV-negative NPC cell line CNE2. We found that EBNA1 consistently altered the levels of a small percentage of the nuclear proteins. The identification of 19 of these proteins by mass spectrometry revealed that EBNA1 upregulated three proteins affecting metastatic potential (stathmin 1, maspin, and Nm23-H1) and several proteins in the oxidative stress response pathway, including the antioxidants superoxide dismutase 1 (SOD1) and peroxiredoxin 1 (Prx1). Western blot analysis verified that EBNA1 expression upregulated and EBNA1 silencing downregulated these proteins. In addition, transcripts for stathmin 1 were induced by EBNA1, whereas EBNA1 only affected Prx1 and SOD1 at the protein level. Further investigation of the EBNA1 effects on the redox pathway showed that long-term EBNA1 expression in NPC resulted in increased reactive oxygen species (ROS) and increased levels of the NADPH oxidases NOX1 and NOX2, known to generate ROS. In addition, EBNA1 depletion in EBV-positive cells decreased NOX2 and ROS. The results show multiple roles for EBNA1 in the oxidative stress response pathway and suggest mechanisms by which EBNA1 may promote NPC metastases.

Analysis of epitope regions for autoantibodies in catalase

Catalase is reported to be one of the target antigens for autoantibodies in various pathologies. To understand the mechanism of autoantibody production, we compared the several properties of autoantigenic epitopes (AE)-1 and -2 of mouse catalase, which reported to react with antibodies from sera of Helicobacter hepaticus-infected mice; AE-3 and -4 of rat catalase, which we found to be susceptible to autoimmunity; and antigenic epitope (E)-1 of H. pylori catalase, which is recognized by monoclonal antibodies produced by immunized mice. Amino acid sequences of AE-1 and -2 were similar among both mammalian and pathogenic microorganism catalases, whereas that of E-1 differed. Amino acid sequences of AE-3 and -4 were similar among mammalian catalases but differed from pathogenic microorganism catalases. Based on local relative rates of evolution, these vertebrate catalases were divided into 5 segments. E-1 included a faster evolving region, whereas AE-1 and -2 included a slowly evolving region; AE-3 and -4 comprised a slowly evolving patch within a faster evolving region. In conclusion, although AE-1 and -2 of catalase have been reported to contribute to autoimmune responses in animals infected with catalase-producing pathogens, AE-3 and -4 appear to have a different mechanism for autoantibody production.