Grape seed extract as photochemopreventive agent against UVB-induced skin cancer

Antioxidants in Photoaging: From Molecular Insights to Clinical Applications

Photoaging (PA) is considered a silent disease affecting millions of people globally and is defined as skin damage due to prolonged exposure to ultraviolet radiation (UVR) from the sun. Physiologically, the skin is in a state of renewal and synthesis of components of the extracellular matrix (ECM). However, exposure to UVR affects the production of the ECM, and the functioning and response of skin cells to UVR begins to change, thus expressing clinical and phenotypic characteristics of PA. The primary mechanisms involved in PA are direct damage to the DNA of skin cells, increases in oxidative stress, the activation of cell signaling pathways responsible for the loss of skin integrity, and cytotoxicity. The medical and scientific community has been researching new therapeutic tools that counteract PA, considering that the damage caused by UVR exceeds the antioxidant defense mechanisms of the skin. Thus, in recent years, certain nutraceuticals and phytochemicals have been found to exhibit potential antioxidant and photoprotective effects. Therefore, the main objective of this review is to elucidate the molecular bases of PA and the latest pharmaceutical industry findings on antioxidant treatment against the progression of PA.

Role of a Polyphenol-Enriched Blueberry Preparation on Inhibition of Melanoma Cancer Stem Cells and Modulation of MicroRNAs

Melanoma is a type of skin cancer known for its high mortality rate. Cancer stem cells (CSCs) are a subpopulation of cancer cells that significantly contribute to tumour recurrence and differentiation. Epigenetic-specific changes involving miRNAs maintain CSCs. Plant polyphenols have been reported to be involved in cancer chemoprevention and chemotherapy, with miRNAs being the novel effectors in their biological activities. A polyphenol-enriched blueberry preparation (PEBP) derived from fermented blueberries has demonstrated promising chemopreventative properties on breast cancer stem cells by influencing inflammatory pathways and miRNAs. In our current investigation, we seek to unveil the impact of PEBP on inhibiting melanoma development and to elucidate the underlying mechanisms. Our study employs various human cell lines, including an ex vivo cell line derived from a patient's metastatic tumour. We found that it elevates miR-200c, increasing E-cadherin expression and inhibiting miR-210-3p through NF-κB signalling, impacting Epithelial-to-Mesenchymal Transition (EMT), a critical process in cancer progression. PEBP increases the SOCS1 expression, potentially contributing to miR-210-3p inhibition. Experiments involving miRNA manipulation confirm their functional roles. The study suggests that PEBP's anti-inflammatory effects involve regulating miR-200c and miR-210 expression and their targets in EMT-related pathways. The overall aim is to provide evidence-based supportive care and preclinical evaluation of PEBP, offering a promising strategy for skin cancer chemoprevention.

Grape Seed Components as Protectors of Inflammation, DNA Damage, and Cancer

PURPOSE OF REVIEW

Oxidative stress is related to the pathogenesis of several chronic diseases, including inflammatory processes. Free radicals excess increase not only oxidative stress but also genomic instability. Polyphenols are non-enzymatic antioxidants that act as a defense barrier against free radicals and non-radical oxidants. The purpose of this article was to review published articles relating dietary polyphenols contained in grape seed proanthocyanidin extracts with its potential for reversing DNA damage.

RECENT FINDINGS

Proanthocyanidin components exert pleiotropic actions having several biological, biochemical, and significant pharmacological effects and showed the ability to reduce cytotoxicity and genotoxicity. Grape seed proanthocyanidin extracts showed the ability to reduce cytotoxicity and genotoxicity through the comet assay and the micronucleus technique.

Protective effects of volatile components of aged garlic extract against ultraviolet B-induced apoptosis in human skin fibroblasts

Aged garlic extract (AGE) has been shown to protect the skin against UV-induced damage, but effects of its volatile components remain unknown. We investigated the effects of the volatile fraction of AGE on the responses of cultured skin fibroblasts subjected to UV-B irradiation. UV-B irradiation (20 mJ/cm² ) reduced the cell viability to 55% of control. The nonvolatile and volatile fractions of AGE inhibited the UV-B-induced reduction of cell viability; the cell viabilities were 100% and 73%, respectively. The volatile fraction inhibited the UV-B-induced increase in apoptotic cell death by 28%. The volatile fraction also inhibited the phosphorylation of mitogen-activated protein kinases (MAPKs) induced by UV-B irradiation. GC-MS analysis revealed that a large number of volatile compounds were generated during aging of garlic. These results suggest that the volatile fraction of AGE has protective effects against the UV-B-induced death of skin fibroblasts, and that this effect may partly be due to an inhibition of apoptosis via the downregulation of MAPK signaling. The volatile compounds of AGE may have beneficial applications for skin health. PRACTICAL APPLICATIONS: In this study, we investigated the effects of AGE against cell damage of UV-B-irradiated human skin fibroblasts. The aging process of garlic produced characteristic volatile compounds that have significant protective effects against UV-induced cell damage. Our results demonstrated that the aging process is a suitable method to develop added value in garlic extracts to improve skin health.

Assessing Photosensitized Membrane Damage: Available Tools and Comprehensive Mechanisms

Lipids are important targets of the photosensitized oxidation reactions, forming important signaling molecules, disorganizing and permeabilizing membranes, and consequently inducing a variety of biological responses. Although the initial steps of the photosensitized oxidative damage in lipids are known to occur by both Type I and Type II mechanisms, the progression of the peroxidation reaction, which leads to important end-point biological responses, is poorly known. There are many experimental tools used to study the products of lipid oxidation, but neither the methods nor their resulting observations were critically compared. In this article, we will review the tools most frequently used and the key concepts raised by them in order to rationalize a comprehensive model for the initiation and the progression steps of the photoinduced lipid oxidation.

Keratinocyte Carcinoma and Photoprevention: The Protective Actions of Repurposed Pharmaceuticals, Phytochemicals and Vitamins

Simple Summary

Keratinocyte carcinoma is the most common type of cancer. Sun exposure and ultraviolet radiation are significant contributors to the development of carcinogenesis, mediated by DNA damage, increased oxidative stress, inflammation, immunosuppression and dysregulated signal transduction. Photoprevention involves using different compounds to delay or prevent ultraviolet radiation-induced skin cancer. In this review, we look at new avenues for systemic photoprevention that are based on pharmaceuticals, plant-derived phytochemicals and vitamins. We also investigate the mechanisms underlying these strategies for preventing the onset of carcinogenesis.

Abstract

Ultraviolet radiation (UVR) arising from sun exposure represents a major risk factor in the development of keratinocyte carcinomas (KCs). UVR exposure induces dysregulated signal transduction, oxidative stress, inflammation, immunosuppression and DNA damage, all of which promote the induction and development of photocarcinogenesis. Because the incidence of KCs is increasing, better prevention strategies are necessary. In the concept of photoprevention, protective compounds are administered either topically or systemically to prevent the effects of UVR and the development of skin cancer. In this review, we provide descriptions of the pathways underlying photocarcinogenesis and an overview of selected photoprotective compounds, such as repurposed pharmaceuticals, plant-derived phytochemicals and vitamins. We discuss the protective potential of these compounds and their effects in pre-clinical and human trials, summarising the mechanisms of action involved in preventing photocarcinogenesis.

Antioxidant activity of polyphenolic compounds obtained from Euphorbia antisyphilitica by-products

In this study, an alternative extraction technique, ultrasound-assisted extraction, was used to extract the polyphenolic fraction from two different residues of the candelilla plant (Euphorbia antisyphilitica). These metabolites were further analyzed to evaluate their bioactivity as antioxidants. In addition, their functional groups were identified by Fourier transform infrared (FTIR) spectroscopy. The antioxidant assays showed statistically significant differences between the phenolic extracts, with citric acid residues (CAR) exhibiting a higher oxidant effect than sulfuric acid residues (SAR). The CAR from San Jerónimo (SJ) cultivar showed decreased IC50 values (179.441 ± 7.92 μL mL-1, DPPH•), and its polyphenolic fraction was able to inhibit lipid oxidation (70.31 ± 2.50%). FTIR analysis subsequently revealed the presence of functional groups related to polyphenolic compounds, such as hydroxy, carbonyl, carbon double bond, and amine groups. In addition, FTIR spectra showed slight differences in phenolic compounds, due to the strong acid treatment involved in the extraction of wax. The present study demonstrated that candelilla by-products from citric acid-wax extraction have a polyphenolic fraction with strong antioxidant activity, which may be useful in food and pharmaceutical products.

Grape Stem Extracts with Potential Anticancer and Antioxidant Properties

The application of plant extracts for therapeutic purposes has been used in traditional medicine because plants contain bioactive compounds with beneficial properties for health. Currently, the use of these compounds that are rich in polyphenols for the treatment and prevention of diseases such as cancer, diabetes, and cardiovascular diseases, many of them related to oxidative stress, is gaining certain relevance. Polyphenols have been shown to have antimutagenic, antioxidant, and anti-inflammatory properties. Therefore, the objective of the present work was to study the potential effect of grape stem extracts (GSE), rich in phenolic compounds, in the treatment of cancer, as well as their role in the prevention of this disease associated with its antioxidant power. For that purpose, three cancer lines (Caco-2, MCF-7, and MDA-MB-231) were used, and the results showed that grape stem extracts were capable of showing an antiproliferative effect in these cells through apoptosis cell death associated with a modification of the mitochondrial potential and reactive oxygen species (ROS) levels. Additionally, grape stem extracts showed an antioxidant effect on differentiated intestinal cells that could protect the intestine from diseases related to oxidative stress. Therefore, grape extracts contain bioactive principles with important biological properties and could be used as bio-functional food ingredients to prevent diseases or even to improve certain aspects of human health.

Differential Modulation of Autophagy Contributes to the Protective Effects of Resveratrol and Co-Enzyme Q10 in Photoaged Mice

BACKGROUND

In photoaging, the accumulation of ultraviolet (UV)-induced oxidative damage leads to the characteristic hallmarks of aging. Here arises the importance of autophagy as a cellular degradation process that cleans the cells of defective or aged organelles and macromolecules, thus maintaining cellular homeostasis. In spite of this, the exact impact of autophagy in photoaging is still elusive.

OBJECTIVE

To evaluate the protective effects of resveratrol and/or co-enzyme-Q10 against the UVA-induced alterations and to explore the role of autophagy in their proposed benefits.

METHODS

Sixty female mice were randomly divided into normal control, untreated UVA-exposed, resveratrol (50mg/kg), co-enzyme-Q10 (100mg/kg), and resveratrol/co-enzyme-Q10-treated UVA-- exposed groups. Clinical signs of photoaging were evaluated using a modified grading score and the pinch test. Skin malondialdehyde and reduced glutathione were assessed as markers of oxidative stress. Tissues were examined for histopathological signs of photodamage, and autophagic changes were determined by immunohistochemical detection of LC3 and P62 in the different cells of the skin.

RESULTS

UVA-exposure increased the oxidative stress with subsequent epidermal and dermal injury. This was associated with the stimulation of autophagy in the keratinocytes and inhibition of autophagic flux in the fibroblasts and infiltrating macrophages. Both drugs corrected the impaired pinch test, macro-and microscopic changes, and exhibited distinct staining patterns with anti-LC3 and P62 in the different cell types denoting autophagic modulation.

CONCLUSION

Changes in autophagic flux are strongly implicated in photoaging associated skin damage and the differential modulation of autophagy by resveratrol and, to a lesser extent by Co-enzyme- Q10, is partially involved in their therapeutic benefits.

Plant Phenolics: Bioavailability as a Key Determinant of Their Potential Health-Promoting Applications

Phenolic compounds are secondary metabolites widely spread throughout the plant kingdom that can be categorized as flavonoids and non-flavonoids. Interest in phenolic compounds has dramatically increased during the last decade due to their biological effects and promising therapeutic applications. In this review, we discuss the importance of phenolic compounds' bioavailability to accomplish their physiological functions, and highlight main factors affecting such parameter throughout metabolism of phenolics, from absorption to excretion. Besides, we give an updated overview of the health benefits of phenolic compounds, which are mainly linked to both their direct (e.g., free-radical scavenging ability) and indirect (e.g., by stimulating activity of antioxidant enzymes) antioxidant properties. Such antioxidant actions reportedly help them to prevent chronic and oxidative stress-related disorders such as cancer, cardiovascular and neurodegenerative diseases, among others. Last, we comment on development of cutting-edge delivery systems intended to improve bioavailability and enhance stability of phenolic compounds in the human body.

An Update on the Role of Dietary Phytochemicals in Human Skin Cancer: New Insights into Molecular Mechanisms

Human skin is continuously subjected to environmental stresses, as well as extrinsic and intrinsic noxious agents. Although skin adopts various molecular mechanisms to maintain homeostasis, excessive and repeated stresses can overwhelm these systems, leading to serious cutaneous damage, including both melanoma and non-melanoma skin cancers. Phytochemicals present in the diet possess the desirable effects of protecting the skin from damaging free radicals as well as other benefits. Dietary phytochemicals appear to be effective in preventing skin cancer and are inexpensive, widely available, and well tolerated. Multiple in vitro and in vivo studies have demonstrated the significant anti-inflammatory, antioxidant, and anti-angiogenic characteristics of dietary phytochemicals against skin malignancy. Moreover, dietary phytochemicals affect multiple important cellular processes including cell cycle, angiogenesis, and metastasis to control skin cancer progression. Herein, we discuss the advantages of key dietary phytochemicals in whole fruits and vegetables, their bioavailability, and underlying molecular mechanisms for preventing skin cancer. Current challenges and future prospects for research are also reviewed. To date, most of the chemoprevention investigations have been conducted preclinically, and additional clinical trials are required to conform and validate the preclinical results in humans.

Whole Fruit Phytochemicals Combating Skin Damage and Carcinogenesis

Skin is arguably the largest organ of the body and is continuously subjected to intrinsic, extrinsic, and environmental stresses. Therefore, skin developed elaborate mechanisms to maintain homeostasis, including antioxidant, antiinflammatory, and DNA damage repair capabilities. However, repeated and excessive stresses can overwhelm these systems, causing serious cutaneous damages, including skin carcinogenesis. Phytonutrients present in the diet possess a myriad of health-promoting effects by protecting skin from damaging free radicals as well as by other mechanisms. Although many chemoprotective phytonutrients have been shown to be efficacious individually, a combination of multiple agents could have synergistic response in curtailing or preventing cutaneous damages. Here, we discuss the benefits of natural amalgamation of phytonutrients in select fruits against skin damage including carcinogenesis. However, a majority of these studies have been done in preclinical models. Therefore, clinical studies are needed to determine the human relevance of the available preclinical data, especially in the human population who are at higher risk for skin cancers (e.g., organ transplant patients). In addition, detailed well-structured preclinical animal studies in the models of high-risk skin carcinogenesis could also be useful toward informing the design for human trials.

Potential health benefits of phenolic compounds in grape processing by-products

Prevention emerges as a powerful approach in minimizing the risk of deleterious lifestyle diseases because therapies do not necessarily guarantee a permanent cure. Accordingly, consumers' growing preference for natural and health-promoting dietary options that are rich in antioxidants has become widespread. Grape (Vitis vinifera) is an antioxidant-rich fruit extensively grown for fresh or processed consumption. The long-term consumption of its polyphenolic antioxidants may promote multiple health benefits. However, grape pomace (GP), consisting of peel, seed, stem, and pulp, is discarded during grape processing, including juice extraction and winemaking, despite its substantial antioxidant content. Polyphenolic extraction techniques have been widely explored to date, but the consolidation of reported physiological impacts of GP-derived polyphenolic constituents is limited. Thus, this review highlights current studies of the potential applications of GP extract in disease prevention and treatment, emphasizing the major influence of polyphenolic compositions and origins of different grape varieties.

Implications of grape extract and its nanoformulated bioactive agent resveratrol against skin disorders

The grape seed extract (GSE) and its main active polyphenol, resveratrol (RES), have shown considerable antioxidant activities, besides possessed protective and therapeutic effects against various skin complications. This paper discusses the favorable effects of RES, GSE and their nanoformulations for dermatological approaches, with specific emphasis on clinical interventions. In this manner, electronic databases including PubMed, Science Direct and Google Scholar were searched. Data were collected from 1980 up to February 2019. The search terms included "Vitis vinifera", "grape", "resveratrol", "skin", "dermatology", and "nanoformulation". To increase the skin permeability of GSE and RES, several innovative nanoformulation such as liposomes, niosomes, solid-lipid nanoparticles, nanostructured lipid carriers, and lipid-core nanocapsule has been evaluated. According to our extensive searches, both RES and GSE have beneficial impacts on skin disorders such as chloasma, acne vulgaris, skin aging, as well as wound and facial redness. More clinical studies with nanoformulation approaches are recommended to achieve conclusive outcomes regarding the efficacy of RES and GSE in the management of skin diseases.

Total phenylethanoid glycosides and magnoloside IafromMagnolia officinalisvar.bilobafruits inhibit ultraviolet B-induced phototoxicity and inflammation through MAPK/NF-κB signaling pathways

Magnolia officinalisvar.bilobais used as a traditional medicine in China and as a food additive in the United Kingdom and the European Union.

In vitro and in vivo anti-inflammatory properties of green synthesized silver nanoparticles using Viburnum opulus L. fruits extract

A green, rapid and cost effective method for the bio-synthesis of silver nanoparticles (AgNPs), using polyphenols present in European cranberry bush fruit extracts was developed. The obtained AgNPs were characterized by ultra-violet visible spectroscopy (UV-VIS), Fourier transform - infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and X-ray diffraction patterns (XRD). The average size of the spherical AgNPs was found to be 25nm. The anti-inflammatory effect of the biomaterials was investigated, both in vitro (on HaCaT cell line, exposed to UVB radiation) and in vivo (on acute inflammation model in Wistar rats). Our results support the conclusion that the photosynthesized silver nanoparticles present a potent anti-inflammatory activity and could be successfully used as therapeutic tools for treatment of inflammation.

Herbal extracts, lichens and biomolecules as natural photo-protection alternatives to synthetic UV filters. A systematic review

Besides the unquestionable positive effects of solar exposure for human health, UV rays have been widely investigated for toxicology aspects related to excessive UVB and UVA doses, which involve sunburns, skin aging, DNA skin damage and tumorigenesis. At present, synthetic and mineral sunscreens are used to protect against these damages but several natural molecules can provide UV protection, including also synergic effect or enhanced photo stability. Although a large number of herbal extracts and plant origin molecules can deserve potential applications, most of the study reported utilizes different method and different strategies of investigation, making thus difficult to understand the real versus claimed potential. This is possibly one of the reasons why, beside the large body of literature there are no officially approved natural commercial sun-filter but a consistent number of commercially available solar products (sunscreen) on the market that contain herbal derivatives. In this review we have evaluated the papers appeared in the last 15years and we have critically collected the most significant data. Several databases, namely Scifinder, Pubmed, Google Scholar, ISI-Web of Science and Scopus, were used as literature sources; excluding patents and symposium or congress papers. Only articles in the English language have been selected. New formulation, new skin delivery systems, skin penetration enhancers and boosters are most likely the next frontier of investigation in order to better understand the role of whole herbal extracts in exerting their photo protective activity.

Vitis vinifera seeds extract for the modulation of cytosolic factors BAX-α and NF-kB involved in UVB-induced oxidative stress and apoptosis of human skin cells

Background and aims

The depletion of the ozone layer allows overexposure of the skin to UV radiation, which is prolonged due to the increasing life expectancy, together with inappropriate life habits contribute to the increasing incidence of cutaneous malignancies. Plant extracts with antioxidant capacities are frequently employed as a means to protect skin against ultraviolet (UV) radiations, thus preventing skin cancers. In the present study we assessed a red grape seed extract (GSE) potential capacities to reduce ultraviolet B (UVB) radiation-induced reactive oxygen species (ROS) and subsequent apoptosis in a human keratinocytes cell line (HaCaT). We identified molecules and pathways modulated by the GSE through which this may exert its photoprotective effect.

Methods

The GSE was standardized according to its polyphenolic content and the most important biologically active compounds, such as epigallocatechin and epicatechin, catechin hydrate, procyanidin B and gallic acid were evidenced by high-performance liquid chromatography. According to the plant extract cytotoxicity on the HaCaT cell line, two concentrations were selected for testing from the non-toxic range: GSE₁ (37.5 μgEqGA/ml) and GSE₂ (75 μgEqGA/ml). The level of ROS was evaluated with CM-H₂DCFDA assay, while apoptosis, Bax-α and NF-kβ p65 proteins with ELISA and confirmed by western-blot.

Results

Both concentrations of the extract decreased the level of ROS in UVB-irradiated keratinocytes (p<0.001), whereas apoptosis and Bax-α pro-apoptotic protein were only reduced by the higher concentration (GSE₂). The NF-kB p65 protein level registered increasing values in time after UVB exposure of the cells, while the tested plant extract re-established its level when its smaller concentration was used (GSE₁).

Conclusion

These results encourage further studies on this extract in order to identify other molecules and pathways through which this extract might exert its beneficial effects and also recommend its use as a potential photoprotective agent.

Photoprotective Effect of Lotus (Nelumbo nucifera Gaertn.) Seed Tea against UVB Irradiation

Lotus (Nelumbo nucifera Gaertn.) seed is widely used as a traditional medicine in countries of Asia. Among many functions of the lotus seed, one interesting activity is its skin protection from the sunlight and scar. In this study, we focused on the skin protective property of lotus seed tea against ultraviolet B (UVB) irradiation. Two groups of a hairless mouse model, water as control (water group) and lotus seed tea (LST group), were administrated a fluid drink water for six months. After 6 month of administration, UVB exposure was carried out to both groups for another 3 months. During and after the administration, the skin moisture content and the morphological and histopathological analyses through biopsy were carried out. Prior to UVB irradiation, no significant difference was discovered in the skin moisture content for the water group and LST group (P<0.05). However, drastic changes were observed after the UVB treatment. The LST group showed a clear evidence of skin protection compared to the control group (P<0.05). The moisture content, epidermal and horny layer thickness, and protein carbonyl values all revealed that the intake of the lotus seed tea enhanced protection against UVB exposure. As a result, the long-term intake of the lotus seed tea showed the effect of preventing loss of skin moisture, mitigating the formation of abnormal keratinocytes, and contributing to protein oxidation inhibition.

Photoprotection by Punica granatum seed oil nanoemulsion entrapping polyphenol-rich ethyl acetate fraction against UVB-induced DNA damage in human keratinocyte (HaCaT) cell line

There has been an increase in the use of botanicals as skin photoprotective agents. Pomegranate (Punica granatum L.) is well known for its high concentration of polyphenolic compounds and for its antioxidant and anti-inflammatory properties. The aim of this study was to analyze the photoprotection provided by P. granatum seed oil nanoemulsion entrapping the polyphenol-rich ethyl acetate fraction against UVB-induced DNA damage in the keratinocyte HaCaT cell line. For this purpose, HaCaT cells were pretreated for 1h with nanoemulsions in a serum-free medium and then irradiated with UVB (90-200 mJ/cm(2)) rays. Fluorescence microscopy analysis provided information about the cellular internalization of the nanodroplets. We also determined the in vitro SPF of the nanoemulsions and evaluated their phototoxicity using the 3T3 Neutral Red Uptake Phototoxicity Test. The nanoemulsions were able to protect the cells' DNA against UVB-induced damage in a concentration dependent manner. Nanodroplets were internalized by the cells but a higher proportion was detected along the cell membrane. The SPF obtained (~25) depended on the concentration of the ethyl acetate fraction and pomegranate seed oil in the nanoemulsion. The photoprotective formulations were classified as non-phototoxic. In conclusion, nanoemulsions entrapping the polyphenol-rich ethyl acetate fraction show potential for use as a sunscreen product.

Concentration effects of grape seed extracts in anti-oral cancer cells involving differential apoptosis, oxidative stress, and DNA damage

BACKGROUND

Grape seeds extract (GSE) is a famous health food supplement for its antioxidant property. Different concentrations of GSE may have different impacts on cellular oxidative/reduction homeostasis. Antiproliferative effect of GSE has been reported in many cancers but rarely in oral cancer.

METHODS

The aim of this study is to examine the antioral cancer effects of different concentrations of GSE in terms of cell viability, apoptosis, reactive oxygen species (ROS), mitochondrial function, and DNA damage.

RESULTS

High concentrations (50-400 μg/ml) of GSE dose-responsively inhibited proliferation of oral cancer Ca9-22 cells but low concentrations (1-10 μg/ml) of GSE showed a mild effect in a MTS assay. For apoptosis analyses, subG1 population and annexin V intensity in high concentrations of GSE-treated Ca9-22 cells was increased but less so at low concentrations. ROS generation and mitochondrial depolarization increased dose-responsively at high concentrations but showed minor changes at low concentrations of GSE in Ca9-22 cells. Additionally, high concentrations of GSE dose-responsively induced more γH2AX-based DNA damage than low concentrations.

CONCLUSIONS

Differential concentrations of GSE may have a differentially antiproliferative function against oral cancer cells via differential apoptosis, oxidative stress and DNA damage.

Malondialdehyde-derived epitopes in human skin result from acute exposure to solar UV and occur in nonmelanoma skin cancer tissue

Cutaneous exposure to solar ultraviolet radiation (UVR) is a causative factor in photoaging and photocarcinogenesis. In human skin, oxidative stress is widely considered a key mechanism underlying the detrimental effects of acute and chronic UVR exposure. The lipid peroxidation product malondialdehyde (MDA) accumulates in tissue under conditions of increased oxidative stress, and the occurrence of MDA-derived protein epitopes, including dihydropyridine-lysine (DHP), has recently been substantiated in human skin. Here we demonstrate for the first time that acute exposure to sub-apoptogenic doses of solar simulated UV light (SSL) causes the formation of free MDA and protein-bound MDA-derived epitopes in cultured human HaCaT keratinocytes and healthy human skin. Immunohistochemical staining revealed that acute exposure to SSL is sufficient to cause an almost twenty-fold increase in general MDA- and specific DHP-epitope content in human skin. When compared to dose-matched solar simulated UVA, complete SSL was more efficient generating both free MDA and MDA-derived epitopes. Subsequent tissue microarray (TMA) analysis revealed the prevalence of MDA- and DHP-epitopes in nonmelanoma skin cancer (NMSC). In squamous cell carcinoma tissue, both MDA- and DHP-epitopes were increased more than threefold as compared to adjacent normal tissue. Taken together, these date demonstrate the occurrence of MDA-derived epitopes in both solar UVR-exposed healthy human skin and NMSC TMA tissue; however, the potential utility of these epitopes as novel biomarkers of cutaneous photodamage and a functional role in the process of skin photocarcinogenesis remain to be explored.