8-hydroxy-2--deoxyguanosine and Skin-Neoplasms

Topics: 8-Hydroxy-2'-Deoxyguanosine; Biomarkers; Deoxyguanosine; DNA; DNA Adducts; DNA Damage; DNA Ligases; Forecasting; Humans; Light; Neoplasms, Radiation-Induced; Oxidation-Reduction; Oxidative Stress; Photochemistry; Photosensitivity Disorders; Pyrimidine Dimers; Radiation-Sensitizing Agents; Reactive Oxygen Species; Skin Neoplasms; Ultraviolet Rays

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Anti-Infective Agents; Carcinogens; Cell Transformation, Neoplastic; Deoxyguanosine; DNA; DNA Adducts; DNA Damage; Fluoroquinolones; Guanine; Humans; Models, Chemical; Mutagenesis; Nalidixic Acid; Neoplasms, Radiation-Induced; Oxidation-Reduction; Oxygen; Pteridines; Pterins; Quinolones; Radiation-Sensitizing Agents; Singlet Oxygen; Skin Neoplasms; Sunlight; Superoxides; Ultraviolet Rays

Molecular epidemiology has linked ultraviolet-induced DNA damage with mutagenesis and skin carcinogenesis. Ultraviolet radiation may damage DNA in one of two ways: either directly, leading to lesions such as cyclobutane thymine dimers (T<>T), or indirectly, via photosensitizers that generate free radical species that may ultimately produce such oxidative lesions as 8-oxo-2'-deoxyguanosine. We report the results of a pilot, case control study in which seven, healthy, human volunteers (skin type II; aged 23-56 y; three male, four female) received a suberythemal dose of whole body irradiation from ultraviolet-A-emitting fluorescent tubes used in psoralen plus ultraviolet A therapy. First void, mid-stream urine samples were collected pre-exposure and daily postexposure, for up to 13 d. Analysis of urinary 8-oxo-2'-deoxyguanosine and cyclobutane thymine dimers was by competitive enzyme-linked immunosorbent assay (interassay coefficient of variation < or = 10%) and compared with a matched, control group of unirradiated individuals. A maximal increase in levels of urinary 8-oxo-2'-deoxyguanosine was seen 4 d post-ultraviolet exposure. A subsequent reduction was noted, before finally returning to baseline. Similarly, cyclobutane thymine dimer levels peaked 3 d postexposure, before returning to baseline. In contrast to the 8-oxo-2'-deoxyguanosine analysis, however, a second peak was noted at days 9-11, before again returning to baseline. This is the first report examining urinary 8-oxo-2'-deoxyguanosine and cyclobutane thymine dimers following ultraviolet exposure of healthy human subjects. This work illustrates the induction and time course for excretion of ultraviolet-induced lesions, perhaps alluding to repair and ultimately offering the potential to define psoralen plus ultraviolet A dosage regimes in terms of minimizing DNA damage and hence cancer risk.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Case-Control Studies; Deoxyguanosine; DNA Damage; Enzyme-Linked Immunosorbent Assay; Female; Humans; Male; Middle Aged; Pilot Projects; Psoriasis; PUVA Therapy; Pyrimidine Dimers; Reproducibility of Results; Skin Neoplasms; Ultraviolet Rays

Oxidative stress role on metformin process of dacarbazine (DTIC) inducing resistance of B16F10 melanoma murine cells are investigated. To induce resistance to DTIC, murine melanoma cells were exposed to increasing concentrations of dacarabazine (DTIC-res group). Metformin was administered before and during the induction of resistance to DTIC (MET-DTIC). The oxidative stress parameters of the DTIC-res group showed increased levels of malondialdehyde (MDA), thiol, and reduced nuclear p53, 8-hydroxy-2'-deoxyguanosine (8-OH-DG), nuclear factor kappa B (NF-ĸB), and Nrf2. In presence of metformin in the resistant induction process to DTIC, (MET-DTIC) cells had increased antioxidant thiols, MDA, nuclear p53, 8-OH-DG, Nrf2, and reducing NF-ĸB, weakening the DTIC-resistant phenotype. The exclusive administration of metformin (MET group) also induced the cellular resistance to DTIC. The MET group presented high levels of total thiols, MDA, and reduced percentage of nuclear p53. It also presented reduced nuclear 8-OH-DG, NF-ĸB, and Nrf2 when compared with the control. Oxidative stress and the studied biomarkers seem to be part of the alterations evidenced in DTIC-resistant B16F10 cells. In addition, metformin administration is able to play a dual role according to the experimental protocol, preventing or inducing a DTIC-resistant phenotype. These findings should help future research with the aim of investigating DTIC resistance in melanoma.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Antineoplastic Agents, Alkylating; Antioxidants; Cell Line, Tumor; Dacarbazine; Drug Resistance, Neoplasm; Malondialdehyde; Melanoma, Experimental; Metformin; Mice; NF-E2-Related Factor 2; NF-kappa B; Oxidative Stress; Skin Neoplasms; Tumor Suppressor Protein p53

The current study investigated the prospective effect of Silybum marianum L. and Eucalyptus camaldulensis Dehnh extracts against skin cancer. Skin cancer was induced by 7,12-dimethylbenz(a) anthracene (DMBA) in young Balb/c mice. Plant extracts were administered to animals orally, once/day (100mg/kg, 5 days/week) for the 20 weeks. Anticancer activity was examined via tumor progression, where antimutagenic activity was measured using 8-OHdG and sister chromatid exchange (SCE) levels. Eucalyptus camaldulensis Dehnh. leaves extract and Silybum marianum L. leaves extract significantly reduced 8-OHdG in cultured human lymphocytes in a dose-response manner (P<0.05). Similarly, the leave extracts of both plants significantly reduced chromosomal damage as measured by SCE levels (P<0.05). In the skin painting assay, the leave extracts of both plants significantly delayed the onset of tumors compared to DMBA treated group (P<0.05). The Silybum marianum leaves extract significantly reduced tumor incidence (P<0.01) and papilloma frequency (P<0.01) induced by DMBA. The Eucalyptus camaldulensis leaves extract significantly reduced the number of tumors per animal (P<0.05) and incidence of tumors (P<0.001). The in vitro and in vivo findings showed that leaves of Silybum marianum L. and Eucalyptus camaldulensis Dehnh. extracts might be a promising source for anticancer and antimutagenic agents against human cancer.

Topics: 8-Hydroxy-2'-Deoxyguanosine; 9,10-Dimethyl-1,2-benzanthracene; Animals; Antimutagenic Agents; Carcinogens; Carcinoma; Cell Proliferation; Drug Screening Assays, Antitumor; Eucalyptus; Humans; In Vitro Techniques; Lymphocytes; Mice; Oxidative Stress; Plant Extracts; Plant Leaves; Silybum marianum; Skin; Skin Neoplasms; Tumor Burden

Little is known regarding the role of redox balance regulators in metastatic melanomas, but there is some evidence for a link between epithelial-to-mesenchymal transition (EMT) and cellular redox status.. We compared the immunohistochemical expression of nuclear factor erythroid-2-related factor 2 (NFE2L2), Kelch-like ECH-associated protein 1 (KEAP1), 8-hydroxy-2'-deoxyguanosine (8-OHdG), TWIST1, SNAI2 and ZEB1 between primary melanomas and metastases in a cohort of 23 nevi, 66 malignant melanomas and 22 metastases.. Nuclear NFE2L2 expression was higher (p=0.003) and cytoplasmic KEAP1 lower (p=0.026) in metastatic lesions than at primary sites. Nuclear NFE2L2 expression was associated with the presence of distant metastases (p=0.040) and with nuclear TWIST1 expression (p=0.002). Patients having both NFE2L2 and TWIST1 expression in nuclei had an extremely poor prognosis (p=0.0003). In multivariate analysis nuclear TWIST1 expression was an independent predictor of a poorer prognosis (HR 2.99, 95% CI 1.17-7.69; p=0.023) and the invasive TWIST1/ZEB1 phenotype showed poorer melanoma-specific survival (HR 7.28, 95% CI 2.23-23.77; p=0.001). Nuclear expression of 8-OHdG (p=0.001) was lower at metastatic sites than in primary lesions.. EMT signalling and the KEAP1/NFE2L2-axis are likely to be involved in metastatic spread of malignant melanoma and also appear to have potential interactions.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Biomarkers, Tumor; Deoxyguanosine; Epithelial-Mesenchymal Transition; Female; Humans; Immunohistochemistry; Kelch-Like ECH-Associated Protein 1; Male; Melanoma; NF-E2-Related Factor 2; Prognosis; Reactive Oxygen Species; Skin Neoplasms; Snail Family Transcription Factors; Survival Rate; Twist-Related Protein 1; Zinc Finger E-box-Binding Homeobox 1

In this study, we developed cationic ultra-flexible nanocarriers (UltraFLEX-Nano) to surmount the skin barrier structure and to potentiate the topical delivery of a highly lipophilic antioxidative diindolylmethane derivative (DIM-D) for the inhibition of UV-induced DNA damage and skin carcinogenesis.. UltraFLEX-Nano was prepared with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, 1,2-dioleoyl-3-trimethylammonium-propane, cholesterol and tween-80 by ethanolic injection method; was characterized by Differential Scanning Calorimetric (DSC), Fourier Transform Infrared (FT-IR) and Atomic Force Microscopic (phase-imaging) analyses and permeation studies were performed in dermatomed human skin. The efficacy of DIM-D-UltraFLEX-Nano for skin cancer chemoprevention was evaluated in UVB-induced skin cancer model in vivo.. DIM-D-UltraFLEX-Nano formed a stable mono-dispersion (110.50±0.71nm) with >90% encapsulation of DIM-D that was supported by HPLC, DSC, FT-IR and AFM phase imaging. The blank formulation was non-toxic to human embryonic kidney cells. UltraFLEX-Nano was vastly deformable and highly permeable across the stratum corneum; there was significant (p<0.01) skin deposition of DIM-D for UltraFLEX-Nano that was superior to PEG solution (13.83-fold). DIM-D-UltraFLEX-Nano pretreatment delayed the onset of UVB-induced tumorigenesis (2 weeks) and reduced (p<0.05) the number of tumors observed in SKH-1 mice (3.33-fold), which was comparable to pretreatment with sunscreen (SPF30). Also, DIM-D-UltraFLEX-Nano caused decrease (p<0.05) in UV-induced DNA damage (8-hydroxydeoxyguanosine), skin inflammation (PCNA), epidermal hyperplasia (c-myc, CyclinD1), immunosuppression (IL10), cell survival (AKT), metastasis (Vimentin, MMP-9, TIMP1) but increase in apoptosis (p53 and p21).. UltraFLEX-Nano was efficient in enhancing the topical delivery of DIM-D. DIM-D-UltraFLEX-Nano was efficacious in delaying skin tumor incidence and multiplicity in SKH mice comparable to sunscreen (SPF30).

Topics: 1,2-Dipalmitoylphosphatidylcholine; 8-Hydroxy-2'-Deoxyguanosine; Animals; Antioxidants; Carcinogenesis; Chemoprevention; Cyclin D1; Deoxyguanosine; DNA Damage; Drug Carriers; Drug Compounding; Fatty Acids, Monounsaturated; Female; Gene Expression Regulation, Neoplastic; HEK293 Cells; Humans; Indoles; Interleukin-10; Mice; Nanoparticles; Permeability; Proliferating Cell Nuclear Antigen; Proto-Oncogene Proteins c-myc; Quaternary Ammonium Compounds; Skin; Skin Neoplasms; Tumor Suppressor Protein p53; Ultraviolet Rays

Increased expression and prognostic significance of major redox regulator nuclear factor erythroid-2-related factor (Nrf2) is recognized in many cancers. Our aim was to investigate the role of oxidative stress markers in melanoma.. We characterized the immunohistochemical expression of Nrf2, kelch-like ECH-associated protein 1 (Keap1), BRAF(V600E), 8-hydroxy-2'-deoxyguanosine (8-OHdG) and nitrotyrosine in 36 nevi, 14 lentigo maligna and 71 malignant melanomas. We measured Nrf2 expression in melanoma cell lines and conducted cytotoxicity assays combining BRAF/NRAS ablation and H2O2treatment.. Nuclear Nrf2 expression in melanoma correlated with deeper Breslow (p<0.0005), invasive phenotype (Clark III-V) (p=0.011), nodular growth (p=0.001) and worse melanoma-specific survival (p=0.008). Absence of 8-OHdG in the endothelium was a greater significant predictor of poor prognosis (p=0.024) than ulceration (p=0.17) and had a similar impact on prognosis as Breslow (p=0.024). A decrease of Nrf2 followed the BRAF/NRAS inhibition, but combination of inhibitor with H2O2did not increase cytotoxicity.. Nrf2 and 8-OHdG influence prognosis in melanoma.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Cell Line, Tumor; Deoxyguanosine; Female; Humans; Intracellular Signaling Peptides and Proteins; Kaplan-Meier Estimate; Kelch-Like ECH-Associated Protein 1; Male; Melanoma; NF-E2-Related Factor 2; Oxidative Stress; Proto-Oncogene Proteins B-raf; Signal Transduction; Skin Neoplasms; Tyrosine

The concurrent impact of repeated low-level summer sunlight exposures on vitamin D production and cutaneous DNA damage, potentially leading to mutagenesis and skin cancer, is unknown.. This is an experimental study (i) to determine the dual impact of repeated low-level sunlight exposures on vitamin D status and DNA damage/repair (via both skin and urinary biomarkers) in light-skinned adults; and (ii) to compare outcomes following the same exposures in brown-skinned adults.. Ten white (phototype II) and six South Asian volunteers (phototype V), aged 23-59 years, received 6 weeks' simulated summer sunlight exposures (95% ultraviolet A/5% ultraviolet B, 1·3 standard erythemal doses three times weekly) wearing summer clothing exposing ~35% body surface area. Assessments made were circulating 25-hydroxyvitamin D [25(OH)D], immunohistochemistry for cyclobutane pyrimidine dimer (CPD)-positive nuclei and urinary biomarkers of direct and oxidative (8-oxo-deoxyguanosine) DNA damage.. Serum 25(OH)D rose from mean 36·5 ± 13·0 to 54·3 ± 10·5 nmol L. Low-dose summer sunlight exposures confer vitamin D sufficiency in light-skinned people concurrently with low-level, nonaccumulating DNA damage. The same exposures produce minimal DNA damage but less vitamin D in brown-skinned people. This informs tailoring of sun-exposure policies.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adolescent; Adult; Asia, Southeastern; Biomarkers; Deoxyguanosine; Diet; DNA Damage; DNA Repair; Environmental Exposure; Female; Humans; Male; Middle Aged; Pyrimidine Dimers; Seasons; Skin; Skin Neoplasms; Skin Pigmentation; Sunlight; Vitamin D; Vitamin D Deficiency; Young Adult

Ultraviolet (UV) radiation results in a significant loss in years of healthy life, approximately 1.5 million disability-adjusted life years (DALYs), and is associated with greater than 60,000 deaths annually worldwide that are attributed to melanoma and other skin cancers. Currently, there are no standardized biomarkers or assay panels to assess oxidative stress skin injury patterns in human skin exposed to ionizing radiation. Using biopsy specimens from chronic solar UV-exposed and UV-protected skin, we demonstrate that UV radiation-induced oxidative skin injury can be evaluated by an immunohistochemical panel that stains 8-hydroxydeoxyguanosine (8-OH-dG) to assess DNA adducts, 4-hydroxy-2-nonenal (HNE) to assess lipid peroxidation, and advanced glycation end products (AGEs) to assess protein damage. We believe this panel contains the necessary cellular biomarkers to evaluate topical agents, such as sunscreens and anti-oxidants that are designed to prevent oxidative skin damage and may reduce UV-associated skin aging, carcinogenesis, and inflammatory skin diseases. We envision that this panel will become an important tool for researchers developing topical agents to protect against UV radiation and other oxidants and ultimately lead to reductions in lost years of healthy life, DALYs, and annual deaths associated with UV radiation.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aldehydes; Deoxyguanosine; DNA Adducts; Glycation End Products, Advanced; Humans; Immunohistochemistry; Lipid Peroxidation; Melanoma; Oxidative Stress; Skin; Skin Neoplasms; Ultraviolet Rays

The objective of this study was to demonstrate the anti-skin cancer and chemopreventive potential of 1,1-bis(3'-indolyl)-1-(p-chlorophenyl methane) (DIM-D) using an in vitro model.. In vitro cell cytotoxicity and viability assays were carried out in A431 human epidermoid carcinoma cell line and normal human epidermal keratinocytes (NHEK) respectively by crystal violet staining. Apoptosis induction in A431 cells (DIM-D treated) and NHEK cells pretreated with DIM-D (2 hr) prior to UVB irradiation, were assessed. The accumulation of reactive oxygen species (ROS) in DIM-D pretreated NHEK cells (2 hr) prior to UVB exposure was also determined. Immunocytochemistry and western blot analysis was performed to determine cleaved caspase 3 and DNA damage markers in DIM-D treated A431 cells and in DIM-D pretreated NHEK cells prior to UVB irradiation.. The IC50 values of DIM-D were 68.7 ± 7.3, 48.3 ± 10.1 and 11.5 ± 3.1 μM whilst for Epigallocatechin gallate (EGCG) were 419.1 ± 8.3, 186.1 ± 5.2 and 56.7 ± 3.1 μM for 24, 48 and 72 hr treatments respectively. DIM-D exhibited a significantly (p<0.05) greater induction of DNA fragmentation in A431 cells compared to EGCG with percent cell death of 38.9. In addition, DIM-D induced higher expression in A431 cells compared to EGCG of cleaved caspase 3 (3.0-fold vs. 2.4-fold changes), Nurr1 (2.7-fold vs. 1.7-fold changes) and NFκB (1.3-fold vs. 1.1-fold changes). DIM-D also exhibited chemopreventive activity in UVB-irradiated NHEK cells by significantly (p<0.05) reducing UVB-induced ROS formation and apoptosis compared to EGCG. Additionally, DIM-D induced expression of Nurr1 but reduced expression of 8-OHdG significantly in UVB-irradiated NHEK cells compared to EGCG and UV only.. Our results suggest that DIM-D exhibits Nurr1-dependent transactivation in the induction of apoptosis in A431 cells and it protects NHEK cells against UVB-induced ROS formation and DNA damage.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Apoptosis; Blotting, Western; Catechin; Cell Line, Tumor; Cell Survival; Cells, Cultured; Chemoprevention; Deoxyguanosine; Dose-Response Relationship, Drug; Humans; Immunohistochemistry; Indoles; Inhibitory Concentration 50; Keratinocytes; Nuclear Receptor Subfamily 4, Group A, Member 2; Oxidative Stress; Reactive Oxygen Species; Skin Neoplasms; Ultraviolet Rays

Nicotinamide (vitamin B3) protects from ultraviolet (UV) radiation-induced carcinogenesis in mice and from UV-induced immunosuppression in mice and humans. Recent double-blinded randomized controlled Phase 2 studies in heavily sun-damaged individuals have shown that oral nicotinamide significantly reduces premalignant actinic keratoses, and may reduce new non-melanoma skin cancers. Nicotinamide is a precursor of nicotinamide adenine dinucleotide (NAD(+)), an essential coenzyme in adenosine triphosphate (ATP) production. Previously, we showed that nicotinamide prevents UV-induced ATP decline in HaCaT keratinocytes. Energy-dependent DNA repair is a key determinant of cellular survival after exposure to DNA-damaging agents such as UV radiation. Hence, in this study we investigated whether nicotinamide protection from cellular energy loss influences DNA repair. We treated HaCaT keratinocytes with nicotinamide and exposed them to low-dose solar-simulated UV (ssUV). Excision repair was quantified using an assay of unscheduled DNA synthesis. Nicotinamide increased both the proportion of cells undergoing excision repair and the repair rate in each cell. We then investigated ssUV-induced cyclobutane pyrimidine dimers (CPDs) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8oxoG) formation and repair by comet assay in keratinocytes and with immunohistochemistry in human skin. Nicotinamide reduced CPDs and 8oxoG in both models and the reduction appeared to be due to enhancement of DNA repair. These results show that nicotinamide enhances two different pathways for repair of UV-induced photolesions, supporting nicotinamide's potential as an inexpensive, convenient and non-toxic agent for skin cancer chemoprevention.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Cell Line; Deoxyguanosine; DNA; DNA Damage; DNA Glycosylases; DNA Repair; Humans; Keratinocytes; Niacinamide; Pyrimidine Dimers; Skin; Skin Neoplasms; Ultraviolet Rays

Arsenic causes several human cancers. Arsenic-induced Bowen's disease (As-BD), the most common arsenical cancer, is characterized by increased proliferation, dysplasia, and individual cell apoptosis, all of which involve mitochondria. We reported that arsenic causes aberrant keratinocyte proliferation through mtTFA-mediated mitochondrial biogenesis in As-BD. Increasing mitochondrial biogenesis causes cells to undergo oxidative stress. However, how arsenic induces oxidative stress and causes mtDNA damage in arsenical cancers remains largely unknown. Using tissues from As-BD patients and arsenic-treated keratinocytes, we determined the oxidative stress, antioxidant enzymes, DNA-repair enzymes, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) level in mtDNA by immunofluorescence, real-time PCR, and western blot. The results showed that oxidative stress was enhanced in both As-BD and arsenic-treated keratinocytes. Antioxidant enzymes including manganese-superoxide anion and copper/zinc-superoxide anion and DNA-repair enzymes were upregulated concomitantly in tissues and cells. In arsenic-treated keratinocytes, increased mitochondrial oxidative stress and the 8-OHdG level in mtDNA were attenuated by pretreatment with ascorbic acid, a potent antioxidant. Further, we found several somatic mutations in the ND4, ND5, and ND6 genes of mtDNA in lesional but not in perilesional skin from As-BD patients. Taken together, the results suggest that oxidative damage and mutations to mtDNA might be involved in the arsenical skin cancers in the context of mitochondrial biogenesis.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Aged, 80 and over; Antioxidants; Apoptosis; Arsenic; Bowen's Disease; Case-Control Studies; Cell Proliferation; Cells, Cultured; Deoxyguanosine; DNA Damage; DNA Repair Enzymes; DNA, Mitochondrial; Humans; Keratinocytes; Middle Aged; Mutation; Oxidative Stress; Skin Neoplasms; Superoxides

Overexposure of the skin to carcinogenic insults causes a variety of adverse effects, among them the development of skin carcinomas. Since there is a need to develop efficient chemopreventive agents based on nutrition, our goal was to determine antioxidant and anti-carcinogenic properties of grapes by evaluating grape powder developed by the California Table Grape Commission. In order to elucidate the mechanism(s) of action of grape powder, three of the major antioxidant components found in grapes-resveratrol, catechin, quercetin, and grape seed extract, containing a proanthocyanidin B-2-gallate-were evaluated for their abilities to inhibit oxidative stress and to protect the immune system. Tested antioxidants given topically and/or systemically strongly inhibited 7,12-dimethylbenz[a]anthracene (DMBA)-induced epidermal hyperplasia, proliferation, and inflammation. The hydroxylation of 2'-deoxyguanosine was markedly inhibited by topical and dietary administration of test variables, i.e., by approximately 40-70%. Simultaneous dietary and topical treatment with antioxidants reduced these biomarkers, showing strong additive and in some combinations synergistic effects. DMBA-mediated Ha-ras mutations in codon 61 were reduced by up to 50% with topical applications, but much higher inhibition was observed in mice treated with different combinations. The results of the present study clearly show impressive effects of combined topical and dietary treatments with above grape-derived antioxidants.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Antioxidants; Body Weight; Cyclooxygenase 2; Deoxyguanosine; Eating; Freeze Drying; Genes, ras; Mice; Mutation; Powders; Skin Neoplasms; Vitis

UV exposure induces skin cancer, in part, by inducing immune suppression. Repairing DNA damage, neutralizing the activity of cis-urocanic acid, and reversing oxidative stress abrogate UV-induced immune suppression and skin cancer induction, suggesting that DNA, UCA, and lipid photo-oxidation serve as UV photoreceptors. What is not clear is whether signaling through each of these different photoreceptors activates independent pathways to induce biological effects or whether there is a common checkpoint where these pathways converge. Here, we show that agents known to reverse photocarcinogenesis and photoimmune suppression, such as platelet-activating factor (PAF) and serotonin (5-HT) receptor antagonists, regulate DNA repair. Pyrimidine dimer repair was accelerated in UV-irradiated mice injected with PAF and 5-HT receptor antagonists. Nucleotide excision repair (NER), as measured by unscheduled DNA synthesis, was accelerated by PAF and 5-HT receptor antagonists. Injecting PAF and 5-HT receptor antagonists into UV-irradiated Xeroderma pigmentosum complementation group A-deficient mice, which lack the enzymes responsible for NER, did not accelerate photoproduct repair. Similarly, UV-induced formation of 8-oxo-deoxyguanosine was reduced by PAF and 5-HT receptor antagonists. We conclude that PAF and 5-HT receptor antagonists accelerate DNA repair caused by UV radiation, which prevents immune suppression and interferes with photocarcinogenesis.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Deoxyguanosine; DNA Repair; Immune Tolerance; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Oxidative Stress; Piperazines; Platelet Activating Factor; Reactive Oxygen Species; Serotonin Antagonists; Skin Neoplasms; Ultraviolet Rays; Urocanic Acid; Xeroderma Pigmentosum; Xeroderma Pigmentosum Group A Protein

8-hydroxy-2'-deoxyguanosine (8-OHdG) is one of the main mutagenic modifications induced in DNA by oxidative stress. Elevated levels of 8-OHdG have been regarded as an independent prognostic factor in different types of cancer. Various enzymes, such as human 8-oxoguanine DNA-glycosylase 1 (hOGG1) and glucose-6-phosphate dehydrogenase (G6PD), act as protection against oxidative stress. The low activity of such enzymes has been consistently associated with increased risk of progression in several tumor types. The aim of this study was to investigate whether 8-OHdG, hOGG1 and G6PD expression in tumor tissues might be a predictor of survival in melanoma patients. The expression of 8-OHdG, hOGG1 and G6PD was immunohistochemically investigated in primary cutaneous melanoma and the effect on survival was analyzed. Furthermore, the immunostaining for p53 and survivin was evaluated and the relationship among 8-OHdG, hOGG1, G6PD, p53 and survivin expression was analyzed. Kaplan-Meier analysis demonstrated that patients with low expression of nuclear 8-OHdG had significantly longer survival time compared with those with a high expression (P=0.032), whereas cancer-specific survival of patients was not associated with hOGG1 or G6PD expression. These results suggest an involvement of oxidative DNA damage in the process of melanoma pathogenesis and demonstrate that 8-OHdG expression in nuclei of tumor cells could be useful as an early independent prognostic marker in patients with primary cutaneous melanoma.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adolescent; Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Cell Nucleus; Child; Child, Preschool; Deoxyguanosine; Female; Humans; Male; Melanoma; Middle Aged; Prognosis; Skin Neoplasms; Survival Analysis; Young Adult

To investigated the relationship between skin-tumor promotion and oxidative stress caused by dimethylated arsenic in mice.. The experimental animal model was used to examine the effect of dimethylated arsenic, a metabolite of DMA(V), dimethylarsinous acid (DMA(III)) in skin tumorigenesis in mice. The 8-oxo-2'-deoxyguanosine (8-oxodG) analysis of epidermis was based on the method of HPLC.. When mice were topically treated with trivalent dimethylated arsenic (DMA(III)), a further reductive metabolite of DMA(V), not only an increase in skin tumors but also an elevation of 8-oxodG in epidermis were observed.. These results suggest that tumor promotion due to DMA(V) administration is mediated by DMA(III) through the induction of oxidative stress.

Topics: 8-Hydroxy-2'-Deoxyguanosine; 9,10-Dimethyl-1,2-benzanthracene; Animals; Cacodylic Acid; Carcinogens; Deoxyguanosine; Female; Mice; Mice, Hairless; Oxidative Stress; Skin Neoplasms

UV radiation is an important environmental factor in the pathogenesis of skin aging and cancer. Many harmful effects of UV radiation are associated with generation of reactive oxygen species. Cellular antioxidants prevent the occurrence and reduce the severity of UV-induced photoaging and diseases of the skin. The transcription factor Nrf2 (NF-E2-related factor 2) and its negative regulator protein, Keap1 (Kelch-like-ECH-associated protein 1), are central regulators of cellular antioxidant responses. We used nrf2-null mice to investigate the roles of the Nrf2-Keap1 system in protection of skin from harmful effects of UVB irradiation. A single irradiation with UVB induced stronger and longer lasting sunburn reaction in nrf2-null mice. Histological changes, including epidermal necrosis, dermal edema, inflammatory cell infiltration, sunburn cell formation, TUNEL-positive apoptotic cell formation, and accumulation of oxidative DNA products such as 8-hydroxy-2'-deoxyguanosine after UVB irradiation, were more prominent in nrf2-null mice. These findings indicate that the Nrf2-Keap1 pathway plays an important role in protection of the skin against acute UVB reactions, including cutaneous cell apoptosis and oxidative damage. However, there were no significant differences in skin carcinogenesis between nrf2-null and wild-type mice exposed to chronic UVB irradiation, suggesting that there is a complex and subtle balance between factors promoting and preventing photocarcinogenesis. Journal of Investigative Dermatology (2008) 128, 1773-1779; doi:10.1038/sj.jid.5701245; published online 17 January 2008.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Deoxyguanosine; DNA Damage; Female; In Situ Nick-End Labeling; Intracellular Signaling Peptides and Proteins; Kelch-Like ECH-Associated Protein 1; Mice; Mice, Inbred BALB C; Neoplasms, Radiation-Induced; NF-E2-Related Factor 2; Oxidation-Reduction; Skin Neoplasms; Sunburn; Ultraviolet Rays

Treatment with thymidine dinucleotide (pTT) has well documented DNA-protective effects and reduces development of squamous cell carcinoma in UV-irradiated mice. The preventive effect of pTT on basal cell carcinoma (BCC) was evaluated in UV-irradiated Ptch-1(+/-) mice, a model of the human disease Gorlin syndrome. Topical pTT treatment significantly reduced the number and size (P < 0.001) of BCCs in murine skin after 7 months of chronic irradiation. Skin biopsies collected 24 hours after the final UV exposure showed that pTT reduced the number of nuclei positive for cyclobutane pyrimidine dimers by 40% (P < 0.0002) and for 8-hydroxy-2'-deoxyguanosine by 61% (P < 0.01 compared with vehicle control). Immunostaining with an antibody specific for mutated p53 revealed 63% fewer positive patches in BCCs of pTT-treated mice compared with controls (P < 0.01), and the number of Ki-67-positive cells was decreased by 56% (P < 0.01) in pTT-treated tumor-free epidermis and by 76% (P < 0.001) in BCC tumor nests (P < 0.001). Terminal dUTP nick-end labeling staining revealed a 213% increase (P < 0.04) in the number of apoptotic cells in BCCs of pTT-treated mice. Cox-2 immunostaining was decreased by 80% in tumor-free epidermis of pTT-treated mice compared with controls (P < 0.01). We conclude that topical pTT treatment during a prolonged period of intermittent UV exposure decreases the number and size of UV-induced BCCs through several anti-cancer mechanisms.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Administration, Cutaneous; Animals; Anticarcinogenic Agents; Apoptosis; Basal Cell Nevus Syndrome; Carcinoma, Basal Cell; Cell Nucleus; Cell Size; Deoxyguanosine; Humans; Mice; Patched Receptors; Patched-1 Receptor; Pyrimidine Dimers; Receptors, Cell Surface; Skin; Skin Neoplasms; Thymine Nucleotides; Ultraviolet Rays

Human papillomavirus type 16 (HPV16) is a major causative factor in the development of uterine cervical carcinomas. We investigated the role of E6/E7 in tumor formation. Skin-specific E6/E7 transgenic mice showed approximately twice as many tumors compared with nontransgenic mice in dimethylbenz[a]anthracene (DMBA)-initiated and a 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted two-stage skin carcinogenesis. This model showed a significant increase of epidermal cell proliferation in the transgenic mice. The 8-hydroxy-2'deoxyguanosine (8OH-dG) detection assay showed that oxidative DNA damage was significantly higher in the transgenic mice after TPA treatments. The overexpression of E6/E7 in the skin in the DMBA/TPA two-stage-induced carcinogenesis model aggravated the incidence of tumor formation. HPV16 E6/E7 appears to act as an enhancer of carcinogenesis that requires initiation by DMBA and promotion by TPA.

Topics: 8-Hydroxy-2'-Deoxyguanosine; 9,10-Dimethyl-1,2-benzanthracene; Animals; Deoxyguanosine; Dermis; DNA Damage; Epidermis; Gene Expression; Humans; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Mice, Transgenic; Oncogene Proteins, Viral; Papillomavirus E7 Proteins; Repressor Proteins; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate

We investigated the relationship between lung- and skin-tumor promotion and oxidative stress caused by administration of dimethylarsinic acid (DMA(V)) in mice. The incidence of lung tumors induced by lung tumor initiator (4NQO) and DMA(V) were, as well as 8-oxo-2'-deoxyguanosine (8-oxodG), suppressed by cotreatment with (-)epigallocatechin gallate (EGCG). When mice were topically treated with trivalent dimethylated arsenic (DMA(III)), a further reductive metabolite of DMA(V), not only an increase in skin tumors but also an elevation of 8-oxodG in epidermis were observed. These results suggest that tumor promotion due to DMA(V) administration is mediated by DMA(III) through the induction of oxidative stress.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenoma; Administration, Topical; Animals; Cacodylic Acid; Carcinogenicity Tests; Carcinogens; Deoxyguanosine; Female; Herbicides; Lung Neoplasms; Male; Mice; Mice, Hairless; Oxidative Stress; Skin Neoplasms

The naevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterized by tumorigenesis such as multiple basal cell carcinomas, odontogenic keratocysts and developmental abnormalities such as calcified dural folds and rib-anomalies. Recently, it has been shown that ultraviolet (UV) B exposure produced more BCCs in ptch knockout mice than wild mice.. To Investigate the role of UV in development of BCCs in NBCCS, cellular sensitivity to killing by UVB and removal of UVB-induced oxidative DNA damage were examined using fibroblasts derived from patients with NBCCS under physiologically relevant doses of UVB exposure.. Three patients with NBCCS, a 59-year-old male patient, an 18-year-old boy and a 13-year-old boy were examined by photobiological analysis. Cellular sensitivity to killing by UVB and UVC and removal of oxidative DNA damage caused by UVB were tested using fibroblasts derived from these patients. We measured cellular 8-hydroxydeoxyguanosine (8-OHdG) after UVB exposure up to 24 h after UVB exposure using high-performance liquid chromatography.. All three cell strains derived from the patients with NBCCS were hypersensitive to killing by UVB (D10: 50-70% of normal) but not by UVC. After UVB exposure, the production of 8-OHdG increased dose dependently up to 3200 J m-2 in both NBCCS cells and normal cells. In normal cells, 8-OHdG after UVB exposure returned to its basal level during 24 h, whereas in NBCCS cells the amount of 8-OHdG after 800 J m-2 of UVB exposure did not return to its basal level even after 24 h. The result indicates the removal of 8-OHdG could be impaired in NBCCS cells. Ability in removal of thymine dimers of NBCCS cells was similar to that of normal cells.. Hypersensitivity to UVB can be one of the diagnostic tools of NBCCS for those whose clinical features have not yet completed. Hypersensitivity to cell killing and the impairment of removal of 8-OHdG after UVB exposure may play some role in developing BCCs and other tumours in NBCCS.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adolescent; Adult; Basal Cell Nevus Syndrome; Case-Control Studies; Cell Death; Cells, Cultured; Chromatography, High Pressure Liquid; Deoxyguanosine; Dimerization; Dose-Response Relationship, Radiation; Female; Humans; Male; Middle Aged; Photosensitivity Disorders; Skin Neoplasms; Thymine; Ultraviolet Rays

Photodynamic therapy (PDT) is available for the treatment of various skin tumours and other skin diseases. Ultraviolet (UV) irradiation induces DNA damage, cyclobutane pyrimidine dimers (CPD) (6-4) photoproducts (6-4PP) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), all of which are carcinogenic for the skin. However, effects of PDT on DNA damage and carcinogenesis are unclear.. To compare the production of photoproducts and the induction of skin tumours in mouse epidermis treated with UVB or PDT.. We performed UVB irradiation or ATX-S10(Na)-PDT on the skin of 20 hairless mice, in each case, and analysed DNA damage and tumour induction.. After a single irradiation of UVB on mouse skin, CPD, 6-4PP and 8-OHdG were detected in the nuclei of keratinocytes. In contrast, PDT-treated mouse keratinocytes showed induction of 8-OHdG, but not of CPD or 6-4PP. Skin tumours induced by UVB irradiation (3 kJ m(-2) three times weekly) were observed following 15 weeks of irradiation (mean +/- SEM tumour incidence 3.2 +/- 1.8%; tumour number 3.2 +/- 1.6 per mouse) and increased depending on irradiation times and doses. Following 30 weeks of UVB irradiation (3 kJ m(-2) three times weekly), mean +/- SEM tumour incidence and tumour number were 28.7 +/- 4.8% and 14.2 +/- 2.8% per mouse, respectively. Although skin tumours were also detected in PDT-treated mouse skin following 80 weeks of treatment (mean +/- SEM tumour incidence 9.1 +/- 1.8%; tumour number 12.2 +/- 2.3 per mouse), the number of tumours was not statistically different from untreated mouse skin (mean +/- SEM tumour incidence 4.1 +/- 3.8%; tumour number 5.2 +/- 3.3 per mouse).. PDT induced 8-OHDG but not CPD or 6-4PP, and was shown to be a relatively safe modality following multiple applications to mouse skin.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Cell Transformation, Neoplastic; Deoxyguanosine; DNA Damage; Dose-Response Relationship, Radiation; Female; Keratinocytes; Mice; Mice, Hairless; Neoplasms, Radiation-Induced; Photochemotherapy; Porphyrins; Pyrimidine Dimers; Skin; Skin Neoplasms; Ultraviolet Therapy

The appearance of 8-oxo-2'-deoxyguanosine (8-oxodG) was examined immunohistochemically using an 8-oxodG-monoclonal antibody in 28 cases of arsenic-related human skin tumors and in 20 cases of arsenic-unrelated human skin cancer to determine if the induction of oxidative stress participates in skin tumorigenesis caused by arsenics. The rate of 8-oxodG-positive was significantly higher in arsenic-related human skin cancer (28 of 28, 100%) than in arsenic-unrelated human skin cancer (3 of 20, 15%, P<0.01 by Chi2 test). Moreover, in all the arsenic-related skin samples, 8-oxodG was detected not only in tumor tissues but also in keratosis and normal tissues. These results suggest that the induction of oxidative stress may play an important role in arsenic carcinogenesis.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Aged; Aged, 80 and over; Arsenic Poisoning; Biopsy; China; Deoxyguanosine; DNA Damage; Environmental Exposure; Environmental Pollutants; Female; Humans; Immunohistochemistry; Male; Middle Aged; Oxidative Stress; Skin Neoplasms

Helicobacter pylori (H. pylori) infection has been associated with gastric carcinogenesis, but responsible and detail mechanisms are insufficient by the absence of adequate data. To obtain direct evidence regarding the carcinogenicity of H. pylori, we investigated the initiating and promoting activity of H. pylori water extract (HPE) in two-stage mouse skin carcinogenesis model. HPE treatment, as an initiation, significantly enhanced tumor formation compared with control group. Moreover, HPE treatment increased production of 8-hydroxydeoxyguanosine in epidermal cells and HPE-initiated/TPA-promoted papillomas demonstrated a point mutation of the Ha-ras gene. These results suggest an initiating activity of HPE on two-stage mouse skin carcinogenesis.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Alleles; Animals; Carcinogens; Cell Fractionation; Cocarcinogenesis; Codon; Deoxyguanosine; Disease Progression; DNA; DNA Adducts; DNA Damage; Female; Genes, ras; Helicobacter pylori; Luminescent Measurements; Mice; Mice, Inbred SENCAR; Oxidative Stress; Papilloma; Peroxidase; Point Mutation; Skin; Skin Neoplasms; Superoxides; Tetradecanoylphorbol Acetate; Water

We have previously demonstrated that soybean isoflavone genistein inhibits ultraviolet-B (UVB)-induced skin tumorigenesis in hairless mice. In the present study, we further investigated the possible mechanism(s) of action whereby genistein inhibits photocarcinogenesis with focuses on UVB-induced oxidative events, including hydrogen peroxide (H(2)O(2)) production, lipid peroxidation (as represented by malondialdehyde, MDA), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation in vivo. We demonstrated that subacute exposure to UVB substantially increased the level of H(2)O(2), lipid peroxides, and 8-OHdG in skin of hairless mice. In addition, chronic exposure to low-dose UVB (0.9-1.2 kJ/m(2) for 20 weeks) substantially increased the levels of 8-OHdG not only in the epidermis, but also in the internal organs such as liver, brain, and spleen of mice with exception of kidney. However, genistein did not affect the level of UVB-induced pyrimidine dimmers in the same UVB exposed mouse skin, indicating selective inhibition of oxidative DNA damage by genistein. Induction of H(2)O(2) was independent of UVB fluences whereas the levels of MDA and 8-OHdG were induced in an UVB fluence-dependent manner. The results suggest that H(2)O(2) be generated as an acute cutaneous response to UVB irradiation, while MDA and 8-OHdG are accumulated with increasing UVB exposure and more closely related to chronic effects of UVB radiation. Pre-treatment of animals with 10 micromol of genistein 1 h prior to UVB exposure significantly inhibited UVB-induced H(2)O(2) and MDA in skin and 8-OHdG in epidermis as well as internal organs. Suppression of 8-OHdG formation by genistein has been corroborated in purified DNA irradiated with UVA and B. In summary, our results suggest that UVB irradiation elicit a series of oxidative events, which can be substantially inhibited by isoflavonoid genistein through either direct quenching of reactive oxygen species or indirect antiinflammatory effects. Thus, the antioxidative properties of genistein may explain for the mechanisms of anti-photocarcinogenic action of genistein.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Anticarcinogenic Agents; Brain; Cattle; Deoxyguanosine; DNA Damage; Female; Genistein; Hydrogen Peroxide; In Vitro Techniques; Kidney; Liver; Malondialdehyde; Mice; Mice, Hairless; Oxidation-Reduction; Oxidative Stress; Pyrimidine Dimers; Skin; Skin Neoplasms; Ultraviolet Rays

Concerning arsenic-induced tumorigenesis, an animal model must be developed for understanding the mechanism of human carcinogenesis by arsenics. To determine whether orally administered dimethylarsinic acid (DMA) promotes and causes the progression of skin tumorigenesis, an animal protocol by topical application of dimethylbenz(a)anthracene (DMBA) with or without UVB, a tumor promoter, in hairless mice was used. The administration of DMA by the oral route promoted not only the formation of papillomas induced by DMBA alone but also the formation of malignant tumors induced by way of the formation of atypical keratoses by treatment with DMBA and UVB. A phenomenon, the progression of keratoses-->atypical keratoses-->squamous cell carcinomas (SCCs), observed in the present study may resemble the development of tumors in arsenic-exposed humans. We also discussed the involvement of a reactive oxygen species (ROS), e.g., the dimethylarsenic peroxy radical [(CH3)2AsOO.], produced during the metabolic processing of DMA, in skin and in multi-organ tumorigenesis.

Topics: 8-Hydroxy-2'-Deoxyguanosine; 9,10-Dimethyl-1,2-benzanthracene; Administration, Oral; Animals; Arsenicals; Cocarcinogenesis; Deoxyguanosine; Female; Mice; Mice, Hairless; Mutagens; Reactive Oxygen Species; Skin Neoplasms; Ultraviolet Rays

Reactive oxygen species (ROS) have been shown to be responsible for inducing DNA damage after ultraviolet radiation (UV). Antioxidant, vitamin E and epigallocatechin gallate extracted from green tea, applied topically to the skin, delayed the onset of UV-induced skin cancer in mice. Since olive oil is reported to have a potent antioxidative effect in in vitro system, we asked whether, topical use of olive oil reduces the number and delays the onset of UV-induced skin cancer in mice. We found that super virgin olive oil painted immediately after UVB radiation significantly delayed the onset and reduced the number of skin cancer, but pretreatment of super virgin olive oil and pre- and/or post treatment by regular olive oil neither retarded nor reduced skin cancer formation in UV-irradiated mice. Further, 8-hydroxy-deoxyguanosine (8-OHdG) formation in mice epidermis was apparently reduced by super virgin olive oil painted immediately after UV radiation, although cyclobutane pyrimidine dimers and (6-4) photoproducts were not reduced by olive oil treatment. Our results suggest that daily topical use of super virgin olive oil after sun bathing may delay and reduce UV-induced skin cancer development in human skin, possibly by decreasing ROS-induced 8-OHdG which is responsible for gene mutation.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Administration, Topical; Animals; Antioxidants; Deoxyguanosine; Female; Humans; Mice; Neoplasms, Radiation-Induced; Olive Oil; Plant Oils; Pyrimidine Dimers; Reactive Oxygen Species; Skin Neoplasms; Ultraviolet Rays

There is growing evidence to suggest that solar radiation-induced, oxidative DNA damage may play an important role in skin carcinogenesis. Numerous methods have been developed to sensitively quantitate 8-oxo-2'deoxyguanosine (8-oxodG), a recognised biomarker of oxidative DNA damage. Immunoassays may represent a means by which the limitations of many techniques, principally derived from DNA extraction and sample workup, may be overcome. We report the evaluation of probes to thymine dimers and oxidative damage in UV-irradiated cells and the DNA derived therefrom. Thymine dimers were most readily recognised, irrespective of whether in situ in cells or in extracted DNA. However, using antibody-based detection the more subtle oxidative modifications required extraction and, in the case of 8-oxodG, denaturation of the DNA prior to successful recognition. In contrast, a recently described novel probe for 8-oxodG detection showed strong recognition in cells, although appearing unsuitable for use with extracted DNA. The probes were subsequently applied to examine the relative induction of lesions in cells following UV irradiation. Guanine-glyoxal lesions predominated over thymine dimers subsequent to UVB irradiation, whereas whilst oxidative lesions increased significantly following UVA irradiation, no induction of thymine dimers was seen. These data support the emerging importance of oxidative DNA damage in UV-induced carcinogenesis.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Cell Line, Transformed; Deoxyguanosine; DNA Damage; Humans; Hydrogen Peroxide; Immunohistochemistry; Keratinocytes; Nucleic Acid Denaturation; Oxidation-Reduction; Pyrimidine Dimers; Simian virus 40; Skin Neoplasms; Ultraviolet Rays

Reactive oxygen species have been shown to play a role in ultraviolet light (UV)-induced skin carcinogenesis. Vitamin E and green tea polyphenols reduce experimental skin cancers in mice mainly because of their antioxidant properties. Since olive oil has also been reported to be a potent antioxidant, we examined its effect on UVB-induced skin carcinogenesis in hairless mice. Extra-virgin olive oil was applied topically before or after repeated exposure of mice to UVB. The onset of UVB-induced skin tumors was delayed in mice painted with olive oil compared with UVB control mice. However, with increasing numbers of UVB exposures, differences in the mean number of tumors between UVB control mice and mice pretreated with olive oil before UVB exposure (pre-UVB group) were lost. In contrast, mice that received olive oil after UVB exposure (post-UVB group) showed significantly lower numbers of tumors per mouse than those in the UVB control group throughout the experimental period. The mean number of tumors per mouse in the UVB control, pre-UVB and post-UVB groups was 7.33, 6.69 and 2.64, respectively, in the first experiment, and 8.53, 9.53 and 3.36 in the second experiment. Camellia oil was also applied, using the same experimental protocol, but did not have a suppressive effect. Immunohistochemical analysis of DNA damage in the form of cyclobutane pyrimidine dimers (CPD), (6-4) photoproducts and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in samples taken 30 min after a single exposure of UVB showed no significant difference between UVB-irradiated control mice and the pre-UVB group. In the post-UVB group, there were lower levels of 8-OHdG in epidermal nuclei, but the formation of CPD and (6-4) photoproducts did not differ. Exposure of olive oil to UVB before application abrogated the protective effect on 8-OHdG formation. These results indicate that olive oil topically applied after UVB exposure can effectively reduce UVB-induced murine skin tumors, possibly via its antioxidant effects in reducing DNA damage by reactive oxygen species, and that the effective component may be labile to UVB.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Administration, Topical; Animals; Anticarcinogenic Agents; Deoxyguanosine; Female; Mice; Mice, Hairless; Mice, Inbred BALB C; Olive Oil; Plant Oils; Pyrimidine Dimers; Skin; Skin Neoplasms; Tumor Suppressor Protein p53; Ultraviolet Rays

Arsenic is widely distributed in nature in the form of either metalloids or chemical compounds, which cause a variety of pathologic conditions including cutaneous and visceral malignancies. Recently, reactive oxygen species have been hypothesized to be one of the causes of arsenic-induced carcinogenesis. 8-Hydroxy-2'-deoxyguanosine is one of the major reactive oxygen species-induced DNA base-modified products that is widely accepted as a sensitive marker of oxidative DNA damage. We studied the presence of 8-hydroxy-2'-deoxyguanosine by immunohistochemistry using N45.1 monoclonal antibody in 28 cases of arsenic-related skin neoplasms and arsenic keratosis as well as in 11 cases of arsenic-unrelated Bowen's diseases. The frequency of 8-hydroxy-2'-deoxyguanosine positive cases was significantly higher in arsenic-related skin neoplasms (22 of 28; 78%) than in arsenic-unrelated Bowen's disease (one of 11; 9%) (p < 0.001 by chi2 test). 8-Hydroxy-2'-deoxyguanosine was also detected in normal tissue adjacent to the arsenic-related Bowen's disease lesions. Furthermore, arsenic was detected by neutron activation analysis in the deparaffined skin tumor samples of arsenic-related disease (four of five; 80%), whereas arsenic was not detected in control samples. Our results strongly suggest the involvement of reactive oxygen species in arsenic-induced human skin cancer. Key word: neutron activation analysis.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Aged; Aged, 80 and over; Arsenic; Bowen's Disease; Deoxyguanosine; DNA Damage; Female; Humans; Immunohistochemistry; Male; Middle Aged; Neoplasms; Neutron Activation Analysis; Oxidative Stress; Poisons; Reactive Oxygen Species; Skin; Skin Neoplasms

The mouse skin tumor initiation-promotion model was used to investigate the protective effect of diet restriction in mechanistic and quantitative terms. A total of five groups of 14 male NMRI mice were initiated with 100 nmol 7,12-dimethylbenz[a]anthracene (DMBA) and promoted twice weekly with 2.5, 1.25, or 0.625 nmol 12-O-tetradecanoylphorbol-13-acetate (TPA). Food intake was ad libitum (all 3 TPA dose levels) or restricted to 70% (high and intermediate TPA dose levels). Time of appearance of the first papilloma was recorded for each mouse. Two weeks later, an osmotic minipump delivering 5-bromo-2'-deoxyuridine (BrdU) was implanted and the mouse was killed after 24 h. Cell proliferation in the epidermis was assessed by immunohistochemistry for BrdU incorporated into DNA. 8-hydroxy-2'-deoxyguanosine (8-OH-dG) in epidermal DNA was determined by HPLC/electrochemical detection. The median latency time (t50) for the appearance of skin papilloma in the high-, intermediate-, and low-dose TPA groups fed ad libitum was 9, 15.5, and 23.5 weeks, respectively. The diet-restricted groups (high and intermediate TPA dose) showed t50 values of 16 and 26 weeks. Therefore, diet restriction to 70% had approximately the same protective effect as reducing the dose of TPA by a factor of two. Both the rate of cell proliferation and the level of 8-OH-dG in the epidermis increased with the dose of TPA. Median values were increased 3- to 4-fold at the highest dose. In controls, but not in TPA-treated animals, diet restriction resulted in a decrease for both markers, by 25 and 40% for the labeling index for cell division and the level of 8-OH-dG, respectively. Both markers showed an inverse relationship with the median papilloma latency time. On an individual basis, the correlation was significant in some groups, but only for the labeling index. The data indicate that protection from the skin tumor-promoting effect of TPA by diet restriction could be based more on a reduction of the rate of cell division than on a reduction of oxidative DNA damage.

Topics: 8-Hydroxy-2'-Deoxyguanosine; 9,10-Dimethyl-1,2-benzanthracene; Animals; Body Weight; Carcinogens; Cell Division; Deoxyguanosine; Diet; DNA; DNA Damage; Immunohistochemistry; Male; Mice; Oxidative Stress; Papilloma; Skin Neoplasms; Tetradecanoylphorbol Acetate

The premutagenic oxidative DNA base damage, 7,8-dihydro-8-oxoguanine, is induced in human skin fibroblasts by monochromatic radiation ranging from a UVB wavelength (312 nm) up to wavelengths in the near visible (434 nm). The oxidative damage is not generated by absorption of radiation in DNA but rather by activation of photosensitizers generating genotoxic singlet oxygen species. The spectrum for the yield of the oxidative damage in confluent, non-growing, primary skin fibroblasts shows that it is UVA (above 334 nm) and near visible radiations which cause almost all of this guanine oxidation by natural sunlight in the fibroblast model. We estimate that the total amount of oxidation of guanine induced by sunlight in fibroblasts in the epidermis of the skin equals or exceeds the amount of the major type of direct DNA damage, cyclobutane pyrimidine dimers. In rapidly dividing lymphoblastoid cells, no oxidative guanine damage was induced. However, in melanoma cells almost as much damage as in non-growing fibroblasts (1.1 per 10(4) guanine bases after 1200 kJ/m2 UVA) was found. We conclude that oxidative DNA base damage can probably contribute to the induction of both non-melanoma and melanoma skin cancer by sunlight.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Cells, Cultured; Deoxyguanosine; DNA Damage; Dose-Response Relationship, Radiation; Fibroblasts; Humans; Melanoma; Oxidation-Reduction; Pyrimidine Dimers; Skin; Skin Neoplasms; Spectrum Analysis; Ultraviolet Rays

8-Hydroxy-2'-deoxyguanosine (8-OHdG) is a mutation-prone (G:C to T:A transversion) DNA base-modified product generated by reactive oxygen species or photodynamic action. G:C to T:A transversions are observed in the p53 and ras genes of UVB-induced skin cancers of mice and in squamous and basal cell carcinomas of human skin exposed to sunlight. In the current study, 8-OHdG formation was evaluated in the epidermis of hairless mice after repeated exposure to UVB, and possible mechanisms involved were studied. Exposure of hairless mice to either 3.4 [2 minimal erythema dose (MED)] or 16.8 (10 MED) kJ/m2 of UVB three times a week for 2 wk induced a 2.5- or 6.1-fold increase, respectively, in the levels of 8-OHdG in DNA, compared to the unexposed controls. An immunohistochemical method using a monoclonal antibody specific for 8-OHdG showed stronger and more extensive staining in the nuclei of UV-irradiated epidermal cells than in those of nonirradiated cells. Western blots probed with antibodies against 4-hydroxy-2-nonenal-modified proteins confirmed the involvement of reactive oxygen species in the epidermal damage induced by chronic UVB exposure. 3-Nitro-L-tyrosine was detected in western blots in a concentration-dependent manner, suggesting that peroxynitrite derived from the reaction of nitric oxide and superoxide, both of which were probably released from inflammatory cells, was involved in modifying the DNA bases. Therefore, the formation of 8-OHdG after UVB exposure appears to be regulated by at least three pathways: photodynamic action, lipid peroxidation, and inflammation and may play a role in sunlight-induced skin carcinogenesis.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Deoxyguanosine; Male; Mice; Mice, Hairless; Pyrimidine Dimers; Skin; Skin Neoplasms; Tyrosine; Ultraviolet Rays

Initiation and promotion are major stages in the multistage carcinogenesis process. Formation of initiating carcinogen-DNA base adducts leads to heritable genetic changes, but the tumor-promoting events induced by complete carcinogens have not, as yet, been elucidated. Oxidant production and oxidative DNA damage induced by phorbol esters (i.e., 12-O-tetradecanoyl-phorbol-13-acetate) are associated with tumor promotion, while antioxidants and inhibitors of oxidative DNA damage suppress promotion and carcinogenesis. Our goal was to establish whether a carcinogen that requires oxidative metabolism for its activity can also induce oxidant production and DNA base oxidation. We found that topical treatment of SENCAR mice with 7,12-dimethylbenz[a]anthracene, which induces tumors in 40-50% of the mice, also causes hydrogen peroxide production and formation of oxidized bases (i.e., 8-hydroxyl-2'-deoxyguanosine and 5-hydroxymethyl-2'-deoxyuridine) in epidermal DNA. The levels of oxidized bases were of comparable magnitude to those mediated by the potent tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate. The oxidized bases persisted over several weeks in epidermal DNA. These oxidative events appear to be temporally associated with inflammatory responses that include edema and polymorphonuclear leukocyte infiltration, which remained elevated over longer periods of time and at higher levels than those induced by phorbol ester. Because these processes are usually associated with tumor promotion, our results support the conjecture that oxidative events may be involved in what is operationally referred to as the tumor promotion process by 7,12-dimethylbenz[a]anthracene.

Topics: 8-Hydroxy-2'-Deoxyguanosine; 9,10-Dimethyl-1,2-benzanthracene; Animals; Antioxidants; Carcinogens; DNA; DNA Damage; Female; Guanine; Hydrogen Peroxide; Mice; Mice, Inbred SENCAR; Neutrophils; Oxidation-Reduction; Peroxidase; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate; Thymidine

The question was addressed whether the risk of cancer of an individual in a heterogeneous population can be predicted on the basis of measurable biochemical and biological variables postulated to be associated with the process of chemical carcinogenesis. Using the skin tumor model with outbred male NMRI mice, the latency time for the appearance of a papilloma was used as an indicator of the individual cancer risk. Starting at 8 weeks of age, a group of 29 mice was treated twice weekly with 20 nmol of 7,12-dimethylbenz[alpha]anthracene (DMBA) applied to back skin. The individual papilloma latency time ranged from 13.5 to 25 weeks of treatment. Two weeks after the appearance of the first papilloma in each mouse, an osmotic minipump delivering 5-bromo-2'-deoxyuridine was s.c. implanted and the mouse was killed 24 hr later. Levels of DMBA-DNA adducts, of 8-hydroxy-2'-deoxyguanosine, and various measures of the kinetics of cell division were determined in the epidermis of the treated skin area. The levels of 8-hydroxy-2'-deoxyguanosine and the fraction of cells in DNA replication (labeling index for the incorporation of 5-bromo-2'-deoxyuridine) were significantly higher in those mice that showed short latency times. On the other hand, the levels of DMBA-DNA adducts were lowest in animals with short latency times. The latter finding was rather unexpected but can be explained as a consequence of the inverse correlation seen for the labeling index: with each round of cell division, the adduct concentration is reduced to 50% because the new DNA strand is free of DMBA adducts until the next treatment. Under the conditions of this bioassay, therefore, oxygen radical-related genotoxicity and the rate of cell division, rather than levels of carcinogen-DNA adducts, were found to be of predictive value as indicators of an individual cancer risk.

Topics: 8-Hydroxy-2'-Deoxyguanosine; 9,10-Dimethyl-1,2-benzanthracene; Animals; Cell Division; Deoxyguanosine; DNA; DNA Adducts; DNA Damage; DNA Replication; Immunohistochemistry; Kinetics; Male; Mice; Mice, Inbred Strains; Papilloma; Skin; Skin Neoplasms; Time Factors

Significant differences in sensitivity to multistage carcinogenesis have been noted between mice that are sensitive (SENCAR) and resistant (C57BL/6J) to 12-O-tetradecanoylphorbol-13-acetate (TPA). However, the mechanism of this sensitivity has not yet been established. Recent studies from this laboratory have shown that TPA significantly enhances formation of hydrogen peroxide (H2O2) and oxidized DNA bases in SENCAR mouse skin, as it increases the infiltration of polymorphonuclear leukocytes (PMNs), as quantitated by myeloperoxidase (MPO). In the studies reported here, we compared SENCAR and C57BL/6J mice with respect to TPA-mediated edema, hyperplasia, PMN infiltration, oxidant formation and oxidative DNA damage in mouse skin. Topical application of two TPA doses (2x2-40 micrograms, 20 h apart) dose-dependently increased PMN infiltration and oxidant formation in both mouse strains, which was consistent with TPA-induced morphological alterations (edema and hyperplasia). However, at low TPA doses (2-4 micrograms), the increases over controls in the SENCAR mice were significantly greater (P < 0.01) than those in C57BL/6J mice. Comparison of the net values indicated that 4 micrograms TPA enhanced PMN infiltration (MPO units/cm2) and oxidant formation (nmol H2O2/cm2) in SENCAR mice by 7.7- and 11-fold respectively over those present in TPA-treated C57BL/6J mouse skin. At the same dose, TPA also significantly increased formation of thymidine glycol (dTG; 5.5-fold), 5-hydroxymethyl-2'-deoxyuridine (HMdU; 4.9-fold) and 8-hydroxyl-2-deoxyguanosine (8-OHdG; 11.4-fold) in SENCAR mouse epidermis. Then, the levels of all three declined. In C57BL/6J mice, there were virtually no increases at 4 micrograms TPA, but their levels gradually increased with higher TPA doses and reached maxima at 10 micrograms TPA for dTG (1.9-fold increase), at 20 micrograms TPA for 8-OHdG (6.0-fold), and at 30 micrograms TPA for HMdU (1.8-fold). We conclude that the TPA-mediated oxidative events and oxidative DNA modification by different doses of TPA correlate with the promoting potencies of those doses in both mouse strains. Therefore, they could be, at least in part, responsible for the strain-dependent sensitivity to tumor promotion.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Carcinogens; Deoxyguanosine; DNA Damage; Hydrogen Peroxide; Hyperplasia; Mice; Mice, Inbred C57BL; Mice, Inbred Strains; Neutrophils; Peroxidase; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate; Thymidine