DNA damage, oxidative mutagen sensitivity, and repair of oxidative DNA damage in nonmelanoma skin cancer patients

"Slow kill" treatment reduces DNA damage in leukocytes of dogs naturally infected with Dirofilaria immitis

Parasitic diseases are considered to be a cause of oxidative stress which leads to oxidative damage of various molecules including DNA. This can result in mutations, replication errors, and genome instability. Therefore, aim of this study was to measure DNA damage induced by Dirofilaria immitis in the single cells such as dogs' leukocytes using the comet assay. Also, we monitored the effects of antiparasitic treatment on mitigation of sensitivity to DNA damage in leukocytes treated with H2O2 using the in vivo and ex vivo comet assay. The whole blood samples from 34 dogs from Serbia were used, both males and females, from one to 13 years old, both pure and mixed-breeds. A rapid immunochromatographic test (Antigen Rapid Heartworm Ag 2.0 Test Kit, Bionote, Minnesota, USA) was used for the detection of D. immitis antigens. The modified Knott's test and PCR were used in the aim of detecting D. immitis microfilariae in dogs' blood, and evaluating the number of circulating microfilariae during the treatment. The genotoxicity evaluation showed that D. immitis infection resulted in DNA damage in naturally infected dogs, with the highest DNA damage occurring in the group of dogs with severe clinical signs. Treatment with ivermectin and doxycycline decreased DNA damage in leukocytes of dogs in all groups, as the intensity of infection decreased due to applied therapy. Ex vivo comet assay results showed that leukocytes exhibited decreased sensitivity to H2O2-induced DNA damage during treatment. The results of the modified Knott's test and PCR in our study showed that treatment with ivermectin and doxycycline was successful in decreasing the average number of microfilariae during the time and at the end eliminating them from the dogs' blood.

Polymeric Nanoparticles as Tunable Nanocarriers for Targeted Delivery of Drugs to Skin Tissues for Treatment of Topical Skin Diseases

The topical route is the most appropriate route for the targeted delivery of drugs to skin tissues for the treatment of local skin diseases; however, the stratum corneum (SC), the foremost layer of the skin, acts as a major barrier. Numerous passive and active drug delivery techniques have been exploited to overcome this barrier; however, these modalities are associated with several detrimental effects which restrict their clinical applicability. Alternatively, nanotechnology-aided interventions have been extensively investigated for the topical administration of a wide range of therapeutics. In this review, we have mainly focused on the biopharmaceutical significance of polymeric nanoparticles (PNPs) (made from natural polymers) for the treatment of various topical skin diseases such as psoriasis, atopic dermatitis (AD), skin infection, skin cancer, acute-to-chronic wounds, and acne. The encapsulation of drug(s) into the inner core or adsorption onto the shell of PNPs has shown a marked improvement in their physicochemical properties, avoiding premature degradation and controlling the release kinetics, permeation through the SC, and retention in the skin layers. Furthermore, functionalization techniques such as PEGylation, conjugation with targeting ligand, and pH/thermo-responsiveness have shown further success in optimizing the therapeutic efficacy of PNPs for the treatment of skin diseases. Despite enormous progress in the development of PNPs, their clinical translation is still lacking, which could be a potential future perspective for researchers working in this field.

Lymphocyte micronuclei frequencies in skin, haematological, prostate, colorectal and esophageal cancer cases: A systematic review and meta-analysis

Micronucleus (MN) assay has been widely used as a biomarker of DNA damage, chromosomal instability, cancer risk and accelerated aging in many epidemiological studies. In this narrative review and meta-analysis we assessed the association between lymphocyte micronuclei (MNi) and cancers of the skin, blood, digestive tract, and prostate. The review identified nineteen studies with 717 disease subjects and 782 controls. Significant increases in MRi for MNi were observed in the following groups: subjects with blood cancer (MRi = 3.98; 95 % CI: 1.98-7.99; p = 0.000) and colorectal cancer (excluding IBD) (MRi = 2.69; 95 % CI: 1.82-3.98, p < 0.000). The results of this review suggest that lymphocyte MNi are a biomarker of DNA damage and chromosomal instability in people with haematological or colorectal cancers. However, the MRi for lymphocyte MNi in subjects with cancers of skin, prostate, esophagus was not significantly increased. More case-control and prospective studies are warranted to further verify the observed trends and to better understand the role of lymphocyte MNi as a biomarker of cancer risk in blood, skin, digestive tract and prostate.

Micronuclei and Their Association with Infertility, Pregnancy Complications, Developmental Defects, Anaemias, Inflammation, Diabetes, Chronic Kidney Disease, Obesity, Cardiovascular Disease, Neurodegenerative Diseases and Cancer

Micronuclei (MN) are a strong cytogenetic indicator of a catastrophic change in the genetic structure and stability of a cell because they originate from either chromosome breaks or whole chromosomes that have been lost from the main nucleus during cell division. The resulting genetic abnormalities can to lead to cellular malfunction, altered gene expression and impaired regenerative capacity. Furthermore, MN are increased as a consequence of genetic defects in DNA repair, deficiency in micronutrients required for DNA replication and repair and exposure to genotoxic chemicals and ultraviolet or ionising radiation. For all of these reasons, the measurement of MN has become one of the best-established methods to measure DNA damage in humans at the cytogenetic level. This chapter is a narrative review of the current evidence for the association of increased MN frequency with developmental and degenerative diseases. In addition, important knowledge gaps are identified, and recommendations for future studies required to consolidate the evidence are provided. The great majority of published studies show a significant association of increased MN in lymphocytes and/or buccal cells with infertility, pregnancy complications, developmental defects, anaemias, inflammation, diabetes, cardiovascular disease, kidney disease, neurodegenerative diseases and cancer. However, the strongest evidence is from prospective studies showing that MN frequency in lymphocytes predicts cancer risk and cardiovascular disease mortality.

Association between polymorphisms in DNA repair gene XRCC1 and non-melanoma skin cancer risk: a meta-analysis

Objective

Non-melanoma skin cancer (NMSC) is the most common malignancy with annually rising incidence. The aim of this study was to estimate the association between three coding polymorphisms (Arg399Gln, Arg194Trp, and Arg280His) of the DNA repair gene X-ray repair cross-complementing group 1 (XRCC1) and NMSC susceptibility.

Methods

Online databases were searched to retrieve case–control studies published between January 2000 and November 2016. Pooled odds ratio (OR) and 95% confidence interval (CI) were employed to assess the strength of association. Overall, 10 relevant studies were finally included for analysis, including 3,143 NMSC patients and 3,540 controls. For each polymorphism of XRCC1 gene, there were 3,050 cases and 3,463 controls for Arg399Gln, 914 cases and 1,182 controls for Arg194Trp, and 279 cases and 413 controls for Arg280His.

Results

Our results showed that these three polymorphisms in the XRCC1 coding region were not associated with increased risk of NMSC in the total studied population. However, subgroup analysis by ethnicities demonstrated that Gln/Arg genotype of Arg399Gln polymorphism was associated with increased risk of NMSC under the heterogeneous model in Asian populations (Gln/Arg vs Arg/Arg: OR =1.39, 95% CI =1.04–1.87, P=0.03); subgroup analysis by tumor types showed that Trp/Trp genotype of Arg194Trp was positively associated with decreased cancer risk in squamous-cell skin cancer (SCC) type under the homogeneous model (Trp/Trp vs Arg/Arg: OR =0.38, 95% CI =0.16–0.92, P=0.03).

Conclusion

Our results suggested that Arg399Gln variant of XRCC1 gene might be a risk factor for NMSC in Asian populations, and Arg194Trp variant of XRCC1 gene might be a protective factor for patients with SCC. In addition, future case–control studies are still needed to further evaluate the effect of XRCC1 polymorphisms in NMSC risk.

Nicotinamide for skin cancer chemoprevention

Nicotinamide (vitamin B₃ ) has a range of photoprotective effects in vitro and in vivo; it enhances DNA repair, reduces UV radiation-induced suppression of skin immune responses, modulates inflammatory cytokine production and skin barrier function and restores cellular energy levels after UV exposure. Pharmacological doses of nicotinamide have been shown to reduce actinic keratoses and nonmelanoma skin cancer incidence in high-risk individuals, making this a nontoxic and accessible option for skin cancer chemoprevention in this population.

DNA Repair Gene Polymorphisms and Their Relation With DNA Damage, DNA Repair, and Total Antioxidant Capacity in Childhood Acute Lymphoblastic Leukemia Survivors

Oxidative stress and defective DNA repair are major contributory factors in the initiation and progression of carcinogenesis. Chemotherapy and radiotherapy cause oxidative DNA damage, consume antioxidant capacity, and impair DNA repair activity. These effects of chemotherapy and radiotherapy may be contributory factors in the development of secondary malignancy in cancer survivors. Basal, H2O2-induced, and postrepair DNA damage; urinary 8-hydroxydeoxyguanosine level as a marker of oxidatively damaged DNA; and serum total antioxidant capacity were measured; XPD Lys751Gln, XRCC1 Arg399Gln, and XRCC1 Arg194Trp polymorphisms were analyzed in childhood acute lymphoblastic leukemia (ALL) survivors. Basal and H2O2-induced DNA damage were found to be higher in the ALL survivor group versus the control group, however, there was no significant difference between the other parameters. No association was found between the examined parameters and polymorphisms of XPD 751 and XRCC1 399 and both the groups. XRCC1 194Trp allele was found to be associated with a low level of postrepair DNA damage in the ALL survivors. In conclusion, basal DNA damage and susceptibility to oxidation are high in childhood ALL survivors. This situation which may easily lead to occurrence of a secondary cancer does not seem to be a result of deficient DNA repair.

Polymeric nanoparticles-based topical delivery systems for the treatment of dermatological diseases

Human skin not only functions as a permeation barrier (mainly because of the stratum corneum layer) but also provides a unique delivery pathway for therapeutic and other active agents. These compounds penetrate via intercellular, intracellular, and transappendageal routes, resulting in topical delivery (into skin strata) and transdermal delivery (to subcutaneous tissues and into the systemic circulation). Passive and active permeation enhancement methods have been widely applied to increase the cutaneous penetration. The pathology, pathogenesis, and topical treatment approaches of dermatological diseases, such as psoriasis, contact dermatitis, and skin cancer, are then discussed. Recent literature has demonstrated that nanoparticles-based topical delivery systems can be successful in treating these skin conditions. The studies are reviewed starting with the nanoparticles based on natural polymers especially chitosan, followed by those made of synthetic, degradable (aliphatic polyesters), and nondegradable (polyacrylates) polymers; emphasis is given to nanospheres made of polymers derived from naturally occurring metabolites, the tyrosine-derived nanospheres (TyroSpheres™). In summary, the nanoparticles-based topical delivery systems combine the advantages of both the nanosized drug carriers and the topical approach, and are promising for the treatment of skin diseases. For the perspectives, the penetration of ultra-small nanoparticles (size smaller than 40 nm) into skin strata, the targeted delivery of the encapsulated drugs to hair follicle stem cells, and the combination of nanoparticles and microneedle array technologies for special applications such as vaccine delivery are discussed.

An aphidicolin-block nucleotide excision repair assay measuring DNA incision and repair capacity

The objective of the present study was to develop a cellular phenotype assay for nucleotide excision repair (NER), using benzo[a]pyrene diol epoxide (BPDE) as model mutagen. Since in vitro exposure to BPDE may lead to DNA strand breaks resulting from both direct interaction with DNA and incisions introduced by the repair enzymes, we aimed to discriminate between both types of breaks using the comet assay and quantified the DNA strand breaks after in vitro challenge of peripheral blood mononucleated cells (PBMCs) with BPDE in the presence or absence of the DNA polymerase inhibitor aphidicolin (APC). The assay was performed with a low (0.5 microM) and a high (2.5 microM) BPDE concentration. The individual NER capacity was defined as the amount of DNA damage induced by BPDE in presence of APC, diminished with the damage induced by BPDE and APC alone. First, the assay was applied to a NER-deficient human fibroblast cell line (XPA-/-) to validate the methodology. Lower repair capacity and a higher amount of BPDE-induced DNA adducts were observed for the XPA-/- fibroblasts as compared to the wild-type fibroblasts. Repeated experiments on PBMCs from four donors showed low intra-individual, intra-experimental and inter-assay variation for both concentrations, indicating the reliability of the method. To assess the inter-individual variation, the assay was applied to PBMCs from 22 donors, comparing the repair capacity after exposure to 0.5 microM (N = 10) and 2.5 microM (N = 12) BPDE. The repair capacity showed a higher inter-individual variation as compared to the intra-individual variation. Moreover, this difference was more pronounced using the low concentration. All these results indicate the adequacy of the method using this low concentration. Further improvement, however, should be recommended by applying the study with low BPDE concentration in a larger population and taking into account the relevant genotypes for NER.

In vitro benzo[a]pyrene diol epoxide-induced DNA damage and chromosomal aberrations in primary lymphocytes, smoking, and risk of squamous cell carcinoma of the head and neck

Cigarette smoking is a major risk factor for squamous cell carcinoma of the head and neck (SCCHN), but only a fraction of those exposed to cigarette smoke develops SCCHN, suggesting variation in individual susceptibility. Tobacco smoke contains a number of carcinogens that cause various kinds of damage to DNA. In this study, we simultaneously measured benzo[a]pyrene diol epoxide-induced DNA damage and chromosomal aberrations by the comet assay and the mutagen sensitivity assay, respectively, in cultured primary lymphocytes from newly recruited 123 patients with SCCHN and 136 age- and sex-matched controls. Using the control median as the cut-off, the elevated risk of SCCHN was 2.35 (95% CI, 1.37-4.03), 2.28 (95% CI, 1.34-3.98) and 3.25 (95% CI, 1.85-5.07) for high levels of tail extension, tail length and oliver tail moment of the comet assay, respectively, and 1.75 (95% CI, 1.04-2.94) for high levels of chromosomal aberrations of the mutagen sensitivity assay. The effects of these 2 types of measurements were additive; subjects with high levels of both DNA damage and chromosomal aberrations had a 4.77-fold increased risk (95% CI, 2.73-8.36) of SCCHN. Cigarette smoking further elevated this risk to more than 20-fold (OR 23.6; 95% CI, 8.92-62.3). These data support our previous finding that suboptimal repair contributed to susceptibility to SCCHN and the new data further suggests a possible gene-environment interaction that may play an important role in the etiology of SCCHN. Further validation studies are warranted.

Noninvasive Prediction of Prostatic DNA Damage by Oxidative Stress Challenge of Peripheral Blood Lymphocytes

To move closer to the goal of individualized risk prediction for prostate cancer, we used an in vivo canine model to evaluate whether the susceptibility of peripheral blood lymphocytes (PBLs) to oxidative stress-induced DNA damage could identify those individuals with the highest prostatic DNA damage. This hypothesis was tested in a population of 69 elderly male beagle dogs after they had completed a 7-month randomized feeding trial to achieve the broad range of dietary selenium status observed in U.S. men. The alkaline Comet assay was used to directly compare the extent of DNA damage in PBLs with prostatic DNA damage in each dog. Using stepwise logistic regression, the sensitivity of PBLs to oxidative stress challenge with hydrogen peroxide (H(2)O(2)) predicted dogs in the highest tertile of prostatic DNA damage. Dogs with PBLs highly sensitive to H(2)O(2) were 7.6 times [95% confidence interval (95% CI), 1.5-38.3] more likely to have high prostatic DNA damage than those in the H(2)O(2)-resistant group. This risk stratification was observed in multivariate analysis that considered other factors that might influence DNA damage, such as age, toenail selenium concentration, and serum testosterone concentration. Our data show that the sensitivity of PBLs to oxidative stress challenge, but not endogenous DNA damage in PBLs, provides a noninvasive surrogate marker for prostatic DNA damage. These findings lend support to the concept that oxidative stress contributes to genotoxic damage, and that oxidative stress challenge may stratify men for prostate cancer risk.

Ultramicrostructure and clinical implications of satellite foci in front of the head of pterygium

In our previous studies, grey satellite foci were found in the front of heads of pterygia. This research was designed to investigate the ultramicrostructure and clinical implications of these satellite foci. The satellite foci were observed and counted under slit lamp biomicroscope. The patients with eye pterygia were divided into groups in terms of occupation, sex, age, length of history, grade of congestion, and size of the heads. The SPSS 13.0 software was used for statistical analysis. The cap areas and satellite foci were ultramicrostructurally examined. Among the total 62 eyes with pterygium, satellite foci were found in 34. The overall incidence of satellite foci was 54.8%. There were no significant differences in incidence among the subjects of different sex, age, and length of history. There were significant differences in incidence among the patients of different occupation, grades of congestion, and size of heads. Higher grades of congestion, outdoor occupations and larger pterygium heads were associated with higher incidence of satellite foci. High grades of congestion and bigger heads were also correlated with the number of satellite foci. Length of history bore no correlation with number of satellite foci. Histologically, the components of the cap areas and the foci were identical, with both consisting of mass of active fibroblasts. The activated fibroblasts existed in the natural tissue planes between Bowman's layer and basal cell layer. The fibroblasts in the satellite foci and the cap areas of a pterygium show some features of tumor cells and may play a vital role in the development and progression of a pterygium. The presence and amount of satellite foci around a pterygium can be used as an indicator for the speed of its growth.

p53 codon 72 polymorphism, DNA damage and repair, and risk of non-melanoma skin cancer

A very common polymorphism of p53, that of codon 72, codes either for a proline (P72) or an arginine (R72). The two alleles differ in their biological properties: P72 is a stronger inducer of p21, while R72 induces 5-10 times more apoptosis. It is not known, however, whether this polymorphism influences genome stability. The influence of p53 codon 72 polymorphism on cancer risk has been studied for different types of cancer with mixed and inconsistent results. With respect to sporadic non-melanoma skin cancer (NMSC), there are few studies, with small sample sizes, and none in a Latinoamerican population. These studies have found no association between p53 genotype at codon 72 and NMSC. We analyzed whether p53 codon 72 genotype influences genomic stability and the sensitivity of cells to UVB. We also carried out a case-control study of NMSC in a Mexican population which included 204 BCC cases, 42 SCC cases, and 238 controls. There was no association between p53 genotype and basal levels of DNA damage, oxidative DNA damage sensitivity, or DNA repair capacity. R72 dominantly increased the in vitro sensitivity of cells to UVB-induced apoptosis. There was no significant association either between p53 genotype and basal cell carcinoma (BCC), squamous cell carcinoma (SCC) or both combined.