8-hydroxy-2--deoxyguanosine and Papillomavirus-Infections

The Human papillomavirus is responsible for the most common sexually transmitted infection and is also known to be an oncogenic virus that is associated with cervical, anogenital, and head-neck cancers. The present study aims to assess whether oxidative DNA damage is correlated with the grade of HPV-related lesions. Moreover, we evaluated clinical data and unhealthy lifestyles to verify their possible influence on the genesis of oxidative DNA damage in cervical cells. We quantified the amount of 8-Oxo-2'-deoxyguanosine in DNA as a biomarker of oxidative damage in women with and without HPV infection. We also correlated oxidative damage with different stages of cervical lesions and available clinical data (e.g., HPV genotypes). To identify HPV infections, in which proteins with a transforming potential are produced, we performed a qualitative detection of HPV E6/E7 mRNA. Our results showed greater oxidative damage in HPV-related dysplastic cervical lesions compared to samples with normal cytology, especially in women with high-grade squamous intraepithelial lesions. The latter showed a closed link with high-risk HPV genotypes. Reactive oxygen species can induce DNA double-strand breaks in both the host DNA and in the circular viral episome; this could facilitate the integration of the virus, promoting HPV carcinogenesis. Therefore, in HPV-infected women, it could be useful to reduce additional resources of reactive oxygen/nitrogen species (RONS) with a healthy lifestyle.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adolescent; Adult; Biomarkers; Deoxyguanosine; DNA Damage; Female; Humans; Middle Aged; Mutagens; Oncogene Proteins, Viral; Papillomavirus Infections; Reactive Oxygen Species; RNA, Messenger; Uterine Cervical Dysplasia; Young Adult

It is increasingly recognized that microbes that reside in and on human body sites play major roles in modifying the pathogenesis of several diseases, including cancer. However, specific microbes or microbial communities that can be mechanistically linked to cervical carcinogenesis remain largely unexplored. The purpose of the study was to examine the association between cervical microbiota and high-grade cervical intraepithelial neoplasia (CIN 2+) in women infected with high-risk (HR) human papillomaviruses (HPV) and to assess whether the cervical microbiota are associated with oxidative DNA damage as indicated by the presence of cervical cells positive for 8-hydroxy-2'-deoxyguanosine. The study included 340 women diagnosed with CIN 2+ (cases) and 90 diagnosed with CIN 1 (non-cases). Microbiota composition was determined by Illumina sequencing of the 16S rRNA gene amplified from DNA extracted from cervical mucus samples. Measures of alpha/beta-diversity were not associated with either CIN severity or oxidative DNA damage. However, a cervical mucosal community type (CT) dominated by L. iners and unclassified Lactobacillus spp was associated with CIN 2+ (OR = 3.48; 95% CI, 1.27-9.55). Sequence reads mapping to Lactobacillaceae, Lactobacillus, L. reuteri, and several sub-genus level Lactobacillus operational taxonomic units were also associated with CIN 2+ when examined independently (effect size >2.0; P < 0.05). Our 16S rRNA sequencing results need confirmation in independent studies using whole-genome shotgun sequencing and that would allow sharpening the suggested associations at finer taxonomic levels. Our results provide little evidence that DNA oxidative damage mediates the effect of the microbiome on the natural history of HPV infection and CIN severity. Cancer Prev Res; 9(5); 357-66. ©2016 AACR.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Cervix Uteri; Deoxyguanosine; Female; Humans; Microbiota; Middle Aged; Neoplasm Grading; Oxidative Stress; Papillomavirus Infections; Polymerase Chain Reaction; Uterine Cervical Dysplasia; Uterine Cervical Neoplasms; Young Adult

Exposure to cigarette smoke is well documented to increase oxidative stress and could account for higher risk of cervical cancer in smokers. Cervical pre-cancerous lesions that are initiated by human papillomavirus (HPV) infection generally regress in the absence of known risk factors such as smoking. 8-oxodeoxyguanosine (8-oxodG) is a highly mutagenic oxidative DNA lesion that is formed by the oxidation of deoxyguanosine. In the present study, we examined: a) the effect of cigarette smoke condensate (CSC) on 8-oxodG formation in and its removal from HPV-transfected (ECT1/E6 E7), HPV-positive (CaSki) and HPV-negative (C33A) human cervical cancer cells, and b) the cell cycle progression and apoptosis in CSC-treated ECT1/E6 E7 cells. CSC induced 8-oxodG in a dose- (p=0.03) and time (p=0.002)-dependent fashion in ECT1/E6 E7 cells as determined by flow cytometry. A 2.4-fold higher level of 8-oxodG was observed in HPV-positive compared with HPV-negative cells. However, 8-oxodG lesions were almost completely removed 72 h post-exposure in all cell lines as determined by ImageStream analysis. This observation correlates with the 2- and 5-fold increase in the p53 levels in ECT1/E6 E7 and CaSki cells with no significant change in C33A cells. We conclude that: a) cigarette smoke constituents induce oxidative stress with higher burden in HPV-positive cervical cancer cells and b) the significant increase observed in p53 levels in wild-type cervical cells (ECT1/E6 E7 and CaSki) may be attributed to the p53-dependent DNA repair pathway while a p53-independent pathway in C33A cells cannot be ruled out.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Apoptosis; Cell Cycle; Cell Line, Transformed; Cell Line, Tumor; Cell Transformation, Viral; Deoxyguanosine; DNA Damage; DNA Repair; Female; Genes, p53; Human papillomavirus 16; Humans; Nicotiana; Oxidative Stress; Papillomavirus Infections; Risk Factors; Smoke; Uterine Cervical Neoplasms

In HPV-positive cervical carcinoma cells, p53 protein is functionally antagonized by the E6 oncoprotein. We investigated a possible role of p53 in antioxidant defense of HPV-positive cervical cancer cell lines. We found that SiHa cells containing integrated HPV 16 had higher expression of p53 and exhibited the greatest resistant to H2O2-induced oxidative damage, compared with HeLa, CaSki and ME180 cell lines. Downregulation of p53 resulted in the inhibition of p53-regulated antioxidant enzymes and elevated intracellular ROS in SiHa cells. By contrast, the ROS level was not affected in HeLa, CaSki and ME180 cell lines after inhibition of the p53 protein. Under mild or severe H2O2-induced stress, p53-deficient SiHa cells exhibited much higher ROS levels than control SiHa cells. Furthermore, we analyzed cell viability and apoptosis after H2O2 treatment and found that p53 deficiency sensitized SiHa cells to H2O2 damage. Inhibition of p53 resulted in excessive oxidation of DNA; control SiHa cells exhibited a more rapid removal of 8-oxo-7,8-dihydro-2'-deoxyguanosine from DNA compared with p53-deficient SiHa cells exposed to the same level of H2O2 challenge. These data collectively show that endogenous p53 in SiHa cells has an antioxidant function and involves in the reinforcement of the antioxidant defense.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Antioxidants; Deoxyguanosine; DNA Damage; Down-Regulation; Female; HeLa Cells; Human papillomavirus 16; Humans; Hydrogen Peroxide; Oncogene Proteins, Viral; Oxidants; Oxidation-Reduction; Oxidative Stress; Papillomavirus Infections; Repressor Proteins; Tumor Suppressor Protein p53; Uterine Cervical Neoplasms