8-Hydroxyguanosine

Salivary 8-hydroxyguanosine levels in smokers and non-smokers with chronic periodontitis

This case-controlled clinical trial was performed on the salivary 8-hydroxyguanosine (8-OHdG) levels in smokers and non-smokers with chronic periodontitis after non-surgical periodontal therapy. Subjects (N = 40) with periodontitis (smokers and non-smokers) and with clinically healthy conditions (smokers and non-smokers) were assigned to this study. At baseline, clinical periodontal parameters (plaque index, gingival index, pocket probing depth and clinical attachment levels) were evaluated. Saliva samples were obtained pre- and post-treatment to quantify the 8-OHdG levels using Elisa technique. Subjects diagnosed with chronic periodontitis with smoking habit (CPs) and non-smokers (CPns) received scaling and root planing. In clinically healthy subjects with smoking habit (CHs) and non-smokers (CHns), only oral hygiene tutoring was performed. All clinical measurements and salivary collection were repeated in a 3-month recall interval. Data were analyzed using Anova, Tukey post hoc test and Mann-Whitney 'U' tests (P < 0.05). At baseline, CPs and CPns groups showed significantly higher PI, GI, PD and CAL values than those of CHns and CHs (P < 0.001). Baseline salivary levels of 8-OHdG were significantly higher in CPs group (14.775 pg/mL) (P < 0.001) compared to the other groups. All clinical parameters in chronic periodontitis group improved at the 3rd month recall interval, however, with regards to 8-OHdG values, the CP smoker category still had a higher level compared to CP non-smoker. This study reflects an on-going periodontal destructive status in smokers and salivary 8-OHdG levels could be recognized as an oxidative biomarker for determining periodontal tissue destruction.

8-Hydroxyguanosine as a possible RNA oxidative modification marker in urine from colorectal cancer patients: Evaluation by ultra performance liquid chromatography-tandem mass spectrometry

Oxidative RNA damage has been found to be associated with a variety of diseases, and 8-hydroxyguanosine (8-OHG) is a typical marker of oxidative modification of RNA. This guanosine modification is an emerging biomarker for disease detection and determination of 8-OHG in human urine is favored because it is noninvasive to patients. However, due to its poor ionization efficiency in mass spectrometry and trace amount in urine, accurate quantification of this modified nucleoside is still challenging. Herein, a rapid, accurate, sensitive and robust method using solid-phase extraction (SPE) combined with isotope dilution ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed for detection of this oxidative RNA modification in human urine. The limit of detection can reach 1.5 fmol and the method exhibits good precision on intra-day (1.8-3.3%) and inter-day (0.6-1.2%) analyses. Satisfactory recovery (87.5-107.2%) at three spiked levels was achieved by using HLB cartridge for urine pretreatment. Using this method, we quantified 8-OHG in urine from 65 colorectal cancer (CRC) patients and 76 healthy volunteers. The measured level of urinary 8-OHG for CRC patients and healthy controls is 1.91 ± 0.63 nmol/mmol creatinine and 1.33 ± 0.35 nmol/mmol creatinine, respectively. We found the content of 8-OHG in urine was raised in CRC patients patients, implying this oxidative RNA modification marker could act as a potential noninvasive indicator for early screening of CRC. In addition, this study will make contributions to the investigations of the influences of oxidative stress on the formation and development of CRC.

Incorporation of 8-hydroxyguanosine (8-oxo-7,8-dihydroguanosine) 5'-triphosphate by bacterial and human RNA polymerases

Oxidized RNA precursors formed in the nucleotide pool may be incorporated into RNA. In this study, the incorporation of 8-hydroxyguanosine 5'-triphosphate (8-OH-GTP; 8-oxo-7,8-dihydroguanosine 5'-triphosphate) into RNA by Escherichia coli RNA polymerase was examined in vitro, using a primer RNA and a template DNA with defined sequences. 8-OH-GTP was incorporated opposite C and A in the template DNA. Surprisingly, 8-OH-GTP was quite efficiently incorporated by the bacterial RNA polymerase, in contrast to the incorporation of the 2'-deoxyribo counterpart by DNA polymerases, as indicated by the kinetic parameters. The primer was further extended by the addition of a ribonucleotide complementary to the nucleobase adjacent to C or A (the nucleobase opposite which 8-OH-GTP was inserted). Thus, the incorporation of 8-OH-GTP did not completely inhibit further RNA chain elongation. 8-OH-GTP was also incorporated opposite C and A by human RNA polymerase II. These results suggest that 8-OH-GTP in the nucleotide pool can cause the formation of oxidized RNA and disturb the transmittance of genetic information.

8-Hydroxyguanosine and 8-methoxyguanosine possess immunostimulating activity for B lymphocytes

The present paper extends previous observations of Goodman and Weigle (M.G. Goodman and W.O. Weigle, J. Immunol. 128, 2399, 1982) and describes the activation of B lymphocytes by a number of C-8-substituted guanine ribonucleosides. 8-Hydroxyguanosine stimulates both proliferation and differentiation of murine B cells while 8-methoxyguanosine stimulates only differentiation and 8-aminoguanosine has no discernible effect on B-cell activation. The former two compounds also increase the magnitude of the antibody response to the type 2 antigen trinitrophenyl-AECM-Ficoll. These data demonstrate that guanosine, which is itself inhibitory to murine B cells, is converted into an immunostimulatory molecule after substitution at its C-8 position with methoxy or hydroxy groups and the bromo or mercapto group not essential for conferring biological activity to this nucleoside. However, our data also suggest that substitution of different groups at the C-8 position does influence the biological activity of this molecule.

Oxidative stress marker 8-hydroxyguanosine is more highly expressed in prostate cancer than in benign prostatic hyperplasia

Oxidative stress is a primary cause of vascular endothelial damage. In the prostate, ischemia increases the levels of reactive oxygen species, growth factors and cytokines, and induces the development of angiogenesis, which results in cancer progression. The expression levels of an oxidative stress marker, 8-hydroxyguanosine (8-OHdG), were compared between prostate cancer and non-neoplastic prostate tissues. A prostate tissue microarray composed of 10 cases of prostatic adenocarcinoma and 70 cases of benign prostatic hyperplasia was immunohistochemically stained for 8-OHdG. All cases expressed 8-OHdG. The levels of 8-OHdG expression in prostatic cancer (30.0% moderate and 70.0% strong) were significantly higher than those in benign prostatic hyperplasia (71.4% moderate and 28.6% strong; (p<0.01). Notably, 8-OHdG is expressed more highly in prostate cancer tissues in comparison to benign prostate tissues.