| Purpose:The oxidative nucleotide bases in tissues and serum were examined separately using double immunofluorescent staining and ELISA method.The status of EB virus infections in the tissues of NPC was examined useing fluorescence in situ hybridization (FISH). Preliminarily to explore that whether the origination and development of the NPC are related to the oxidative DNA damage, in order to find out the potential biomarkers for the diagnose of NPC.Methods:(1) 57 cases of NPC and 39 cases of chronic nasopharyngitis were investigated to examine the expression of iNOS, the formation of 8-NitroG and 8-OHdG using double immunofluorescent staining. The statistical differences in immunoreactivities were analyzed using a Mann-Whitney test.(2) 36 patients from 57 cases with NPC and a group of 36 noncancer controls were investigated to examine the level of serum 8-OHdG using enzyme-linked immunosorbent assay (ELISA) method. The statistical differences were analyzed using a t test.(3) 57 cases of NPC and 39 cases of chronic nasopharyngitis were investigated to examine the expression of phosphorylated signal transducers and activators of transcription (p-Stat3) and epidermal growth factor receptor (EGFR), using double immunofluorescent staining. The statistical differences in immunoreactivities were analyzed using a Mann-Whitney test. (4) 57 cases of NPC and 39 cases of chronic nasopharyngitis were investigated to examine CD68, the surface antigen of macrophages and its expression product interleukin-6 (IL-6), using double immunofluorescent staining. The statistical differences in immunoreactivities were analyzed using a Mann-Whitney test.(5) 57 cases of NPC and 39 cases of chronic nasopharyngitis were investigated to examine EBV encoded small RNAs (EBER), using fluorescent in situ hybridization (FISH). The statistical differences in immunoreactivities were analyzed using a Mann-Whitney test.Results:(1) Strong DNA lesions were observed in cancer cells of NPC patients. 8-NitroG and 8-OHdG were positive, observed in all cases of NPC (100%). iNOS was observed in fifty-four cases of NPC (94.7%). Samples from NPC exhibited significantly more intense staining for 8-NitroG,8-OHdG and iNOS than those of chronic nasopharyngitis (P<0.05).(2) The mean value of serum 8-OHdG level of thirty-six NPC patients was 0.538±0.336ng/ml compared to 0.069±0.059ng/ml of thirty-six noncancer controls. The difference of 8-OHdG levels in serum of NPC patients and noncancer controls was statistically significant (P<0.05).(3) P-Stat3 and EGFR were positive, both observed in fifty-four cases of NPC (94.7%). Samples from NPC exhibited significantly more intense staining for P-State3 and EGFR than those of chronic nasopharyngitis (P<0.05).(4)CD68 and IL-6 were positive, observed in all cases of NPC (100%). Samples from NPC exhibited significantly more intense staining for CD68 and IL-6 than those of chronic nasopharyngitis (P<0.05).(5) EBER was positive, observed in all cases of NPC (100%). Samples from NPC exhibited significantly more intense staining for EBER than those of chronic nasopharyngitis (P<0.05).Conclusions:(1)The oxidative DNA damage exists in NPC.(2) The oxidative DNA damage was related to the up-regulation of iNOS.(3) The pathological stimulations, such as inflammations from the bacteria, virus and parasite in nasopharyngeal tissues, might lead to nitrative and oxidative DNA lesions by iNOS catalyzed NO, which contribute to the origination and development of NPC. The high expression of iNOS was possibly because of the up-regulation of EGFR owing to TRAFs expression by LMP1. Combining of EGFR and specific ligand EGF or TGF-a union causes the acceptor area self-phosphorylation in the cell and activates Stat3 using its tyrosine activating enzyme activeness. Another circuit of up-regulation of iNOS possibly was because the EB virus exists as the antigen in the nasopharynx epithelial cell, causing the accumulation of nasopharynx department macrophage, T and the B lymphocyte, the blood vessel smooth muscle cell and the neutral granular cell,which secretes inflammatory cell factor like IL-6. p-Stat3 was activated through IL-6/gp130/the Jak pathway. p-Stat3 promotes the iNOS gene expression. As a result of the iNOS high expression, in the cell the NO active oxygen increasing, causes the DNA damage through NO, which finally induces the cancer.(4) 8-NitroG and 8-OHdG could be suitable and promising biomarkers for evaluating the risk of NPC. Better understanding of the mechanisms and role of such nitrative and oxidative DNA damage in NPC is a necessary basis to develop new strategies for cancer prevention by modulating the process of inflammation.
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