Cellular aspects of photocarcinogenesis

ALKBH5-mediated CHAC1 depletion promotes malignant progression and decreases cisplatin-induced oxidative stress in gastric cancer

The m6a demethyltransferase ALKBH5 dynamically modulates gene expression and intracellular metabolic molecules by modifying RNA m6a in cancer cells. However, ALKBH5's function in gastric cancer (GC) has remained controversial. This study demonstrates that ALKBH5 is highly expressed in GC. Silencing ALKBH5 hampers proliferation, and metastatic potential, and induces cell death in GC cells. Through a comprehensive analysis of the transcriptome and m6A sequencing, alterations in certain ALKBH5 target genes, including CHAC1, were identified. ALKBH5's demethylation effect regulates CHAC1 RNA stability, leading to reduced CHAC1 expression. Moreover, CHAC1 modulates intracellular ROS levels, influencing the chemotherapy sensitivity of gastric cancer. In summary, our study unveils the pivotal role of the ALKBH5-CHAC1-ROS axis and highlights the significance of m6A methylation in gastric cancer.

Enzyme-Digested Edible Bird’s Nest (EBND) Prevents UV and arid Environment-Induced Cellular Oxidative Stress, Cell Death and DNA Damage in Human Skin Keratinocytes and Three-Dimensional Epithelium Equivalents

The aim of this study is to investigate the repressive effects of enzyme-digested edible bird’s nest (EBND) on the combination of arid environment and UV-induced intracellular oxidative stress, cell death, DNA double-strand breaks (DSBs) and inflammatory responses in human HaCaT keratinocytes and three-dimensional (3D) epithelium equivalents. An oxygen radical antioxidant capacity assay showed that EBND exhibited excellent peroxyl radical scavenging activity and significantly increased cellular antioxidant capacity in HaCaT cells. When EBND was administered to HaCaT cells and 3D epitheliums, it exhibited significant preventive effects on air-drying and UVA (Dry-UVA)-induced cell death and apoptosis. Dry-UVA markedly induced intracellular reactive oxygen species (ROS) generation in HaCaT cells and 3D epitheliums as quantified by CellROX® Green/Orange reagents. Once HaCaT cells and 3D epitheliums were pretreated with EBND, Dry-UVA-induced intracellular ROS were significantly reduced. The results from anti-γ-H2A.X antibody-based immunostaining showed that EBND significantly inhibited Dry-UVA-induced DSBs in HaCaT keratinocytes. Compared with sialic acid, EBND showed significantly better protection for both keratinocytes and 3D epitheliums against Dry-UVA-induced injuries. ELISA showed that EBND significantly suppressed UVB-induced IL-6 and TNF-α secretion. In conclusion, EBND could decrease arid environments and UV-induced harmful effects and inflammatory responses in human keratinocytes and 3D epithelium equivalents partially through its antioxidant capacity.

Preclinical confirmation of UVC efficacy in treating infectious keratitis

PURPOSE

Preclinical evaluation of the therapeutic potential of antimicrobial 265 nm UVC for infectious keratitis.

METHODS

Four experiments explored UVC: 1) impact on bacterial and fungal lawns on agar, in individual or mixed culture, 2) bacterial inactivation dose in an in vitro deep corneal infection model, 3) dose validation in an ex vivo porcine keratitis model and 4) efficacy in a masked, randomised, controlled murine keratitis trial using bioluminescent Pseudomonas aeruginosa.

RESULTS

Minimum effective UVC exposures ranged between 2 s and 5 s for lawn bacteria and fungi in individual or mixed culture. Significant P. aeruginosa growth inhibition in the in vitro infection model was achieved with 15 s UVC, that resulted in a >3.5 log10 reduction of bacteria in a subsequent ex vivo keratitis model (p < 0.05). Bioluminescence fell below baseline levels in all treated animals, within 8 h of treatment (p < 0.05), in the in vivo study. Re-epithelialisation with corneal clarity occurred within 24 h in 75% of UVC-treated cases, with no relapse at 48 h. On plating, bacteria were recovered only from untreated controls.

CONCLUSIONS

UVC inhibited all tested bacteria and fungi, including mixed culture and strains linked to antibiotic resistance, in vitro, with exposures of ≤ 5 s. In vitro and ex vivo testing confirmed therapeutic potential of 15 s UVC. In vivo, 15 s UVC administered in two doses, 4 h apart, proved effective in treating murine bacterial keratitis.

Cancer incidence and mortality and risk factors in member countries of the " Belt and Road " initiative

BACKGROUND

At present, "Belt and Road" ("B&R") member states (accounting for about 61.78% of the world's population) face different types of cancer threats to varying degrees. We analyzed the incidence and mortality and risk factors of cancer in the member countries of the "B&R" to explore the basis of health and medical cooperation between countries and provide a foundation for formulating cancer prevention and control policies for building a healthy "B&R."

METHODS

Data were derived from the Global Cancer Observatory and Cancer Country Profiles in 2020. Incidence and mortality were age-standardized rates (ASRs). Population attributable fractions (PAFs) was applied to measure risk factors of cancers in the "B&R" countries. The mortality-to-incidence ratio (MIR) was calculated by dividing the mortality rate by the incidence rate.

RESULTS

A total of 26 cancers were included in the study. Lung, breast, colorectal, stomach, liver, prostate, cervical, esophageal, thyroid, and uterine cancers were the most common and highest in age-standardized mortality in the "B&R" countries. For men, Hungary had the highest cancer age-standardized incidence and mortality (ASR, 289.3 per 100,000 and ASR, 235.7 per 100,000, respectively), followed by Latvia (ASR, 288.6 per 100,000 and ASR, 196.5 per 100,000, respectively). In females, the highest incidence rates were estimated in Greece (ASR, 238.7 per 100,000), and the highest mortality rate was Brunei (ASR, 192.3 per 100,000). All countries were in the middle or high HDI range, with about half (46.88%) of countries achieving high HDI, mostly in Central and Eastern Europe (13 countries) and West Asia (10 countries). The United Arab Emirates had the highest MIR in male and female (1.59 vs 2.19). Tobacco products, infectious factors, and ultraviolet rays were the three main cancer risk factors in the "B&R" countries.

CONCLUSION

The overall burden of cancer in the countries along the "B&R" remains substantial, while the corresponding cancer prevention and control policies need to be improved. Strengthening health cooperation among member countries will contribute to a joint response to the risks and challenges posed by cancer.

UVB-Induced Microvesicle Particle Release and Its Effects on the Cutaneous Microenvironment

Ultraviolet B radiation (UVB) has profound effects on human skin that results in a broad spectrum of immunological local and systemic responses and is the major cause of skin carcinogenesis. One important area of study in photobiology is how UVB is translated into effector signals. As the skin is exposed to UVB light, subcellular microvesicle particles (MVP), a subtype of bioactive extracellular vesicles, are released causing a variety of local and systemic immunological effects. In this review, we highlight keratinocyte MVP release in keratinocytes in response to UVB. Specifically, Platelet-activating factor receptor agonists generated by UVB result in MVP released from keratinocytes. The downstream effects of MVP release include the ability of these subcellular particles to transport agents including the glycerophosphocholine-derived lipid mediator Platelet-activating factor (PAF). Moreover, even though UVB is only absorbed in the epidermis, it appears that PAF release from MVPs also mediates systemic immunosuppression and enhances tumor growth and metastasis. Tumor cells expressing PAF receptors can use this mechanism to evade chemotherapy responses, leading to treatment resistance for advanced cancers such as melanoma. Furthermore, novel pharmacological agents provide greater insight into the UVB-induced immune response pathway and a potential target for pharmacological intervention. This review outlines the need to more clearly elucidate the mechanism linking UVB-irradiation with the cutaneous immune response and its pathological manifestations. An improved understanding of this process can result in new insights and treatment strategies for UVB-related disorders from carcinogenesis to photosensitivity.

Role of Xeroderma pigmentosum D (XPD) protein in genome maintenance in human cells under oxidative stress

Xeroderma pigmentosum D (XPD) protein plays a pivotal role in the nucleotide excision repair pathway. XPD unwinds the local area of the damaged DNA by virtue of constituting transcription factor II H (TFIIH) and is important not only for repair but also for basal transcription. Although cells deficient in XPD have shown to be defective in oxidative base-lesion repair, the effects of the oxidative assault on primary fibroblasts from patients suffering from Xeroderma Pigmentosum D have not been fully explored. Therefore, we sought to investigate the role of XPD in oxidative DNA damage-repair by treating primary fibroblasts derived from a patient suffering from Xeroderma Pigmentosum D, with hydrogen peroxide. Our results show dose-dependent increase in genotoxicity with minimal effect on cytotoxicity with H₂O₂ in XPD deficient cells compared to control cells. XPD deficient cells displayed increased susceptibility and reduced repair capacity when subjected to DNA damage induced by oxidative stress. XPD deficient fibroblasts exhibited increased telomeric loss after H₂O₂ treatment. In addition, we demonstrated that chronic oxidative stress induced accelerated premature senescence characteristics. Gene expression profiling revealed alterations in genes involved in transcription and nucleotide metabolisms, as well as in cellular and cell cycle processes in a more significant way than in other pathways. This study highlights the role of XPD in the repair of oxidative stress and telomere maintenance. Lack of functional XPD seems to increase the susceptibility of oxidative stress-induced genotoxicity while retaining cell viability posing as a potential cancer risk factor of Xeroderma Pigmentosum D patients.

Stress-induced miRNAs isolated from wheat have a unique therapeutic potential in ultraviolet-stressed human keratinocyte cells

Increasing evidence supports the existence of cross-kingdom gene regulation. However, the therapeutic potential of stress-specific plant miRNAs and their role in UV-related pathologies in human tissue remain largely unexplored. The aim of this study was to investigate the therapeutic potential and mechanisms of action of stress-induced miRNA cocktails (SI-WmiRs) from Einkorn wheat (Triticum monococcum L.) on human keratinocyte (HaCaT) cells exposed to a high dose of UV-B radiation. We used a biofactory approach and irradiated wheatgrass with UV-C for 240 min to obtain the specific SI-WmiRs that wheat produces to recover from UV stress. We followed the plant with molecular and biochemical analyses and extracted our SI-WmiRs at the most appropriate time (0 h and 6 h after UV-C application). Then, we applied the SI-WmiR cocktail to HaCaT cells exposed to high-dose of UV-B radiation. Our results show that UV-B radiation induced lipid peroxidation and DNA damage, as demonstrated by increased malondialdehyde (MDA) levels and changes in the RAPD band profile, respectively. UV stress also impaired IL6/JAK2/STAT3 signalling and activated the inflammatory mediators IL6 and TNF-α in HaCaT cells, leading to significant induction of apoptotic cell death. We found that SI-WmiR transfection prevents lipid peroxidation and oxidative stress-related DNA damage by increasing antioxidant (CuZn-SOD, Mn-SOD) and DNA repair (EXO1, SMUG1 and XRCC3) gene expression. In addition, SI-WmiRs regulated IL6/JAK2/STAT3 signalling by reducing JAK2 and STAT3 gene expression and phosphorylated protein levels compared to the control treatments. Moreover, SI-WmiRs inhibited pro-apoptotic BAX, Caspase 3 and Caspase 8 gene expression and protein levels to prevent apoptosis of UV-stressed HaCaT cells. Our results demonstrate that stress-induced wheat miRNAs produced using a biofactory approach have strong potential as a novel and effective alternative therapy for UV stress-related skin damage.

Wounding Therapies for Prevention of Photocarcinogenesis

The occurrence of non-melanoma skin cancer (NMSC) is closely linked with advanced age and ultraviolet-B (UVB) exposure. More specifically, the development of NMSC is linked to diminished insulin-like growth factor-1 (IGF-1) signaling from senescent dermal fibroblasts in geriatric skin. Consequently, keratinocyte IGF-1 receptor (IGF-1R) remains inactive, resulting in failure to induce appropriate protective responses including DNA repair and cell cycle checkpoint signaling. This allows UVB-induced DNA damage to proliferate unchecked, which increases the likelihood of malignant transformation. NMSC is estimated to occur in 3.3 million individuals annually. The rising incidence results in increased morbidity and significant healthcare costs, which necessitate identification of effective treatment modalities. In this review, we highlight the pathogenesis of NMSC and discuss the potential of novel preventative therapies. In particular, wounding therapies such as dermabrasion, microneedling, chemical peeling, and fractionated laser resurfacing have been shown to restore IGF-1/IGF-1R signaling in geriatric skin and suppress the propagation of UVB-damaged keratinocytes. This wounding response effectively rejuvenates geriatric skin and decreases the incidence of age-associated NMSC.

Carotenoids from Persimmon (Diospyros kaki Thunb.) Byproducts Exert Photoprotective, Antioxidative and Microbial Anti-Adhesive Effects on HaCaT

Persimmon (Diospyros kaki Thunb.) fruits are a remarkable source of carotenoids, which have shown protective effects against UV radiation in bacteria, fungi, algae, and plants. The aim of this study was to analyze the photoprotection provided by an acetone extract, rich in carotenoids and obtained from byproducts derived from the persimmon juice industry, against UV-induced cell death in the keratinocyte HaCaT cell line. For this purpose, the cytotoxicity and phototoxicity of carotenoid extract, as well as its intracellular reactive oxygen species (ROS) scavenging and anti-adhesive activities towards HaCaT cells, were evaluated. The in vitro permeation test provided information about the permeability of the carotenoid extract. Persimmon extracts, rich in carotenoids (PEC), were absorbed by HaCaT keratinocyte cells, which reduced the UV-induced intracellular ROS production in treated cells. Thus, PEC exerted a photoprotective and regenerative effect on UV-irradiated HaCaT cells, and this protection was UV dose-dependent. No cytotoxic effect was observed in HaCaT cultures at the concentration tested. PEC treatment also stimulated the adhesion capacity of skin microbiome to HaCaT cells, while exhibiting a significant anti-adhesive activity against all tested pathogens. In conclusion, PEC showed potential for use as a functional ingredient in skin-care products.

Bioactive substances in the stratum corneum of the epidermis found as indicators of skin damage due to sun exposure

Background/Purpose

Although an inflammatory response upon acute injury caused by ultraviolet radiation (UV) can be observed immediately, the influence of long‐term, repetitive low‐dose UV exposure on the skin cannot be precisely perceived, making early detection of chronic damage difficult. This study investigated bioactive substances in the stratum corneum as a potential early and sensitive indicator of the influence of sun exposure on the skin using receiver operating characteristic (ROC) analysis.

Methods

Receiver operating characteristic analysis was performed to assess the responsiveness of cytokines [interleukin (IL)‐1α, IL‐1 receptor antagonist (IL‐1ra), IL‐10, tumor necrosis factor (TNF)‐α], BCL2‐associated protein X (Bax), Toll‐like receptor (TLR)3, and TLR4 in the stratum corneum of healthy people exposed (dorsum of the hand) and unexposed (inner arm) to UV. Sunscreen was applied to patients with photodermatosis for 4 weeks to evaluate changes in IL‐1ra/IL‐1α, TNF‐α, Bax, and TLR3 levels after sunscreen application, as these molecules exhibited high responsiveness to sun exposure according to ROC analysis. In addition, IL‐1ra, IL‐1α, and IL‐10 levels were quantified by enzyme‐linked immunosorbent assay, and TNF‐α, Bax, TLR3, and TLR4 levels were semi‐quantitatively assessed by immunocytochemistry.

Results

Receiver operating characteristic analysis identified IL‐1ra/IL‐1α, TNF‐α, Bax, and TLR3 in the stratum corneum as highly responsive to sun exposure. Moreover, in participants, including patients with photodermatosis, IL‐1ra/IL‐1α, TNF‐α, and Bax levels decreased significantly after sunscreen application.

Conclusion

The results revealed that IL‐1ra/IL‐1α, TNF‐α, and Bax in the stratum corneum represent sensitive indicators of the influence of sun exposure on the skin.

The potential effect of Polypodium leucotomos extract on ultraviolet- and visible light-induced photoaging

Photoaging induced by both ultraviolet and visible light has been shown to lead to increased inflammation and dysregulation of the extracellular matrix. Standardized extract of the Polypodium leucotomos fern, PLE, possesses anti-inflammatory and antioxidant properties, and has been shown to potentially mitigate photoaging through various mechanisms. This comprehensive review presents the data available on the effects of P. leucotomos extract on UV and VL-induced photoaging in vitro as well as in vivo in murine and human models.

Effect of therapeutic UVC on corneal DNA: Safety assessment for potential keratitis treatment

PURPOSE

Antimicrobial ultraviolet C (UVC) has proven efficacy in vitro against keratitis isolates and has potential to treat corneal infection if safety can be confirmed.

METHOD

Safety of 265 nm, 1.93 mW/cm² intensity UVC (15-300 s exposures) was investigated in vitro via cyclobutane pyrimidine dimer (CPD) formation in DNA of human cultured corneal epithelial cells; ex vivo, by evaluating UVC transmissibility as a function of porcine corneal thickness; and in vivo, by evaluating CPD induction in the mouse cornea following UVC exposure.

RESULTS

A single exposure of 15 s UVC did not induce significant CPD formation (0.92 ± 1.45%) in vitro relative to untreated control (p = 0.93) whereas 300 s exposure caused extensive CPD formation (86.8 ± 13.73%; p < 0.0001). Cumulative exposure to 15 s UVC daily for 3 days induced more CPD (14.6 ± 8.2%) than a single equivalent 45 s exposure (8.3 ± 4.0%) (p < 0.001) but levels returned to baseline within 72 h (p = 0.29), indicating highly efficient DNA repair. Ex vivo, UVC transmission decreased sharply with increasing corneal thickness, confirming UVC effects are limited to the superficial corneal layers. In vivo evaluations demonstrated no detectable CPD after three consecutive daily 15 s UVC exposures, whereas a single 300 s exposure induced extensive CPD formation in superficial corneal epithelium.

CONCLUSION

Up to three daily doses of 15 s UVC, in vivo, appear safe with respect to CPD formation. Ongoing research exploring UVC as a possible treatment for microbial keratitis is warranted.

Anti‑photoaging and anti‑oxidative activities of natural killer cell conditioned medium following UV‑B irradiation of human dermal fibroblasts and a reconstructed skin model

Conditioned media from various sources comprise numerous growth factors and cytokines and are known to promote the regeneration of damaged tissues. Among these, natural killer cell conditioned medium (NK-CdM) has been shown to stimulate collagen synthesis and the migration of fibroblasts during the wound healing process. With a long-term aim of developing a treatment for skin photoaging, the ability of NK-CdM to prevent ultraviolet-B (UV-B) damage was assessed in neonatal human dermal fibroblasts (NHDFs) and an in vitro reconstructed skin model. The factors present in NK-CdM were profiled using an antibody array analysis. Protein and mRNA levels in UV-B exposed NHDFs treated with NK-CdM were measured by western blotting and quantitative reverse transcription-PCR, respectively. The total antioxidant capacity of NK-CdM was determined to assess its ability to suppress reactive oxygen species. The anti-photoaging effect of NK-CdM was also assessed in a 3D reconstituted human full skin model. NK-CdM induced proliferation of UV-B-treated NHDFs, increased procollagen expression, and decreased matrix metalloproteinase (MMP)-1 expression. NK-CdM also exhibited a potent antioxidant activity as measured by the total antioxidant capacity. NK-CdM inhibited UV-B-induced collagen degradation by inactivating MAPK signaling. NK-CdM also elicited potential anti-wrinkle effects by inhibiting the UV-B-induced increase in MMP-1 expression levels in a 3D reconstituted human full skin model. Taken together, the suppression of both UV-B-induced MMP-1 expression and JNK activation by NK-CdM suggests NK-CdM as a possible candidate anti-skin aging agent.

Occupational differences in standardized mortality ratios for non-melanotic skin cancer and melanoma in exposed areas among individuals with Fitzpatrick skin types III and IV

OBJECTIVE

The objective of this study was to identify subpopulations vulnerable to skin cancer by occupations, among individuals with Fitzpatrick skin types III and IV.

METHODS

Data were retrieved from the national mortality registry of Korean National Statistical Office (KNSO) from 1993 to 2012, including all medical certificates of death written and confirmed by physicians. Medical certificates of death from 1993 to 2012 were obtained from the national mortality registry of Korean National Statistical Office. These completed medical certificates are verified by the Korean Ministry of Government Administration and Home Affairs and formatted using 103 main and 236 specific causes of death as recommended by the World Health Organization. We calculated direct standardized mortality rate and standardized mortality ratio (SMR) using the indirect standardization method. The entire population as reflected in the 2005 national census was used as a reference population.

RESULTS

Of 594 deaths from skin cancer, 227 (38.2%) were from non-melanotic skin cancer (NMSC) and 367 (61.8%) from cutaneous melanoma (CM). Compared to office workers, agriculture/fishery/forestry workers had significantly higher SMRs for NMSC in men [SMR: 461, 95% confidential interval (CI): 329-583] and women (SMR: 575, 95% CI: 317-864). SMR was also increased in men who worked in exposed area (SMR of NMSC:553, 95% CI:222-1018, SMR of CM:453, 95% CI: 133-1009).

CONCLUSION

This is the first Asian study to suggest that agriculture/fishery/forestry workers have increased SMRs for NMSC and CM in exposed areas. Early diagnosis of skin cancer in this group is important.

Marine fungal DHICA as a UVB protectant: Assessment under in vitro and in vivo conditions

The present study explores UVB protective role of a melanin precursor namely DHICA (5,6- Dihydroxyindole-2-carboxylic acid) expressed by the marine imperfect fungus Aspergillus nidulans. In brief, A. nidulans grown in a modified growth medium for the period of 5 days at 25 °C under shaking conditions and the extracellular medium free from fungal biomass used for the extraction of DHICA. The extracted DHICA further exposed to partial purification and subjected to UVB protection studies using HaCaT cells and Balb/c mice independently. DHICA obtained in the present study found soluble in water. Experiments on HaCaT cell compatibility revealed nil cell death up to 500 μM concentration of DHICA. UVB protection studies under in vitro conditions emphasizes DHICA significantly protect HaCaT cells from UVB exposure by quenching the generated ROS, reducing cell apoptosis, maintain the cellular integrity and sequentially down regulating the LPO (Lipid peroxidation) and up-regulating the antioxidant enzyme (SOD (Superoxide Dismutase), Catalase, GPx (Glutathione peroxidase)) respectively. Further, experiments on cell cycle arrest analysis, gelatin zymography, and western blot analysis on COX-2 and TNF-alpha, IHC (Immunohistochemistry) on apoptotic markers (Bax, Bcl2) substantiate the protective role of DHICA. Furthermore, in vivo studies on BALB/c mice carried out and compared with the sunscreen cream with sun protective factor (SPF) of 20. Analysis of skin sections of experimental samples revealed that an appreciable reduction in the epidermal thickness of the skin samples of mice pre-exposed to DHICA followed by UVB exposure compared to UVB exposure alone. RT-PCR results on various inflammatory apoptotic markers also suggested that DHICA has UVB protective potential. The observations made in the present study explore the possible application of DHICA alone as a sun-protective agent for skin care.

Anti-Inflammatory and Skin Barrier Repair Effects of Topical Application of Some Plant Oils

Plant oils have been utilized for a variety of purposes throughout history, with their integration into foods, cosmetics, and pharmaceutical products. They are now being increasingly recognized for their effects on both skin diseases and the restoration of cutaneous homeostasis. This article briefly reviews the available data on biological influences of topical skin applications of some plant oils (olive oil, olive pomace oil, sunflower seed oil, coconut oil, safflower seed oil, argan oil, soybean oil, peanut oil, sesame oil, avocado oil, borage oil, jojoba oil, oat oil, pomegranate seed oil, almond oil, bitter apricot oil, rose hip oil, German chamomile oil, and shea butter). Thus, it focuses on the therapeutic benefits of these plant oils according to their anti-inflammatory and antioxidant effects on the skin, promotion of wound healing and repair of skin barrier.

Topical application of Nexrutine inhibits ultraviolet B-induced cutaneous inflammatory responses in SKH-1 hairless mouse

BACKGROUND

Ultraviolet B (UVB) radiation is the major contributor to skin inflammation which leads to the development of skin cancer. Hence, in this study, we studied the effect of Nexrutine (NX) on UVB-induced cutaneous inflammation and its mediators.

METHODS

Ultraviolet absorption spectra of NX were measured by spectrophotometer. To conduct the photoprotective studies, SKH-1 hairless mice were topically treated with NX, 30 minutes before to the UVB (180 mJ/cm² ) exposure. Twenty hours of post-UVB irradiation, mouse skin was used for edema measurements, H & E staining, myeloperoxidase (MPO) activity, and estimation of plasma cytokines. In addition, expression levels of inflammatory cytokines, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) were also determined by Western blot analysis.

RESULTS

Nexrutine displayed absorbance over the UVB spectrum. NX significantly decreased the UVB-induced epidermal edema, skin thickness, leukocyte infiltration, number of the sunburn, and TUNEL-positive cells. NX treatment also decreased the number of mast cells, MPO activity, expression of pro-inflammatory cytokines, and inflammation mediator protein in mouse skin.

CONCLUSION

These results provide evidences that NX inhibits the UVB-induced cutaneous inflammatory responses in SKH-1 mouse skin.

CXCL1 Inhibition Regulates UVB-Induced Skin Inflammation and Tumorigenesis in Xpa-Deficient Mice

Xeroderma pigmentosum complementation group A is a hereditary disease characterized by early onset of skin cancers and freckle-like pigmented maculae in sun-exposed sites. Although the etiology of the predisposition to UVR-induced skin tumors in xeroderma pigmentosum complementation group A is well investigated as a repair deficiency in UVR-induced DNA damage, the mechanism of exaggerated sunburn in patients with xeroderma pigmentosum complementation group A and whether UVR-induced inflammation relates to a skin tumor-prone phenotype remains to be elucidated. Using gene profiling of xeroderma pigmentosum complementation group A model mice, Xpa-deficient mice, we found that expression of CXCL1 in the skin and blood of Xpa-deficient mice increased significantly after UVB exposure over even a limited area compared with that of wild-type mice. We administered CXCL1 neutralizing antibody or the antioxidant agent, N-acetylcysteine, to Xpa-deficient mice after UVB irradiation and found significant suppression of blood levels of CXCL1, ear swelling and erythema, the hallmarks of inflammation and neutrophil chemotaxis. Xpa-deficient mice treated with chronic UVB exposure plus administration of CXCL1 neutralizing antibody or N-acetylcysteine yielded many fewer skin tumors compared with the control group. This indicates that the UVB-induced strong inflammatory response of Xpa-deficient mice plays a role in skin tumor development, which could be suppressed by regulating chemokines such as CXCL1.

AP-1 Expression and its Clinical Relevance in Immune Disorders and Cancer

The inflammatory response is known to have a significant role in certain autoimmune diseases and malignancies. We review current knowledge regarding the functions of activator protein 1 (AP-1) as an important modulator in several immune disorders and carcinomas. AP-1 is overexpressed in rheumatoid arthritis and in long-term allogeneic hematopoietic stem cell transplantation survivors; however, decreased expression of AP-1 has been observed in psoriasis, systematic lupus erythematosus and in patients who do not survive after hematopoietic stem cell transplantation. AP-1 also is implicated in the control of various cancer cells. Higher levels of AP-1 components are present in breast and endometrial carcinomas, colorectal cancer and in acute myeloid leukemia, Hodgkin׳s lymphoma and anaplastic large cell lymphoma, with downregulation in ovarian and gastric carcinomas and in patients with chronic myelogenous leukemia. AP-1 may enable the development of helpful markers to identify early-stage disease or to predict severity.

Djulis (Chenopodium formosanum Koidz.) Water Extract and Its Bioactive Components Ameliorate Dermal Damage in UVB-Irradiated Skin Models

Dermal photoaging is a condition of skin suffering inappropriate ultraviolet (UV) exposure and exerts inflammation, tissue alterations, redness, swelling, and uncomfortable feelings. Djulis (Chenopodium formosanum Koidz.) is a cereal food and its antioxidant and pigment constituents may provide skin protection from photoaging, but it still lacks proved experiments. In this study, protective effects of djulis extract (CFE) on UVB-irradiated skin were explored. The results showed that HaCaT cells with 150 μg/mL CFE treatment had higher survival and less production of interleukin- (IL-) 6, matrix metalloprotease- (MMP-) 1, and reactive oxygen species (ROS) in UVB-irradiated conditions. Subsequently, in animal studies, mice supplemented with CFE (100 mg/kg BW) were under UVB irradiation and had thinner epidermis and lower IL-6 levels in skin layer. These data demonstrate that bioactive compounds possessing the potency of antiphotoaging exist in CFE. Following that, we found rutin and chlorogenic acid (10-100 μM) could significantly increase cell viability and decrease the production of IL-6 in UVB models. Additionally, djulis pigment-betanin has no effect of increasing cell viability in this study. Our findings suggest CFE can protect skin against UV-induced damage and this protection is mainly from contributions of rutin and chlorogenic acid.

Relevance of HLA-G, HLA-E and IL-10 expression in lip carcinogenesis

HLA-G, HLA-E and IL-10 are molecules which can provide tumor immunosuppression as well as the capacity of evasion to the immune system host. This study set out to evaluate HLA-G, HLA-E and IL-10 expression in lip squamous cell carcinoma (LSCC) and in a potentially malignant disorder (actinic cheilitis - AC), correlating the expression of these proteins with the degree of epithelial dysplasia. Immunohistochemistry was undertaken to identify HLA-G, HLA-E and IL-10 in samples from patients with LSCC (n=20), AC (n=30) and healthy lip mucosa (control) (n=10). A semiquantitative scoring system was used for analysis. Differences between the groups were evaluated using the Pearson Chi-Squared test. The percentage of LSCC samples showing high immunoreactivity (IRS>2) for HLA-G, HLA-E and IL-10 (neoplastic/epithelial cells) and HLA-E (stroma/connective tissue) was significantly higher that of the control (P<0.05). A tendency for a progressive increase in the proteins analyzed was observed from the control to AC and to LSCC. The degree of dysplasia in the AC samples was not significantly associated with the proteins evaluated (P>0.05). The high expression of HLA-G, HLA-E and IL-10 in AC and LSCC reflects the capacity that these pathologies have for evasion and progression.

NRAS and EPHB6 mutation rates differ in metastatic melanomas of patients in the North Island versus South Island of New Zealand

Melanoma, the most aggressive skin cancer type, is responsible for 75% of skin cancer related deaths worldwide. Given that New Zealand (NZ) has the world's highest melanoma incidence, we sought to determine the frequency of mutations in NZ melanomas in recurrently mutated genes. NZ melanomas were from localities distributed between North (35°S-42°S) and South Islands (41°S-47°S). A total of 529 melanomas were analyzed for BRAF exon 15 mutations by Sanger sequencing, and also by Sequenom MelaCarta MassARRAY. While, a relatively low incidence of BRAFV600E mutations (23.4%) was observed overall in NZ melanomas, the incidence of NRAS mutations in South Island melanomas was high compared to North Island melanomas (38.3% vs. 21.9%, P=0.0005), and to The Cancer Genome Atlas database (TCGA) (38.3% vs. 22%, P=0.0004). In contrast, the incidence of EPHB6G404S mutations was 0% in South Island melanomas, and was 7.8% in North Island (P=0.0002). Overall, these data suggest that melanomas from geographically different regions in NZ have markedly different mutation frequencies, in particular in the NRAS and EPHB6 genes, when compared to TCGA or other populations. These data have implications for the causation and treatment of malignant melanoma in NZ.

Fernblock (Polypodium leucotomos Extract): Molecular Mechanisms and Pleiotropic Effects in Light-Related Skin Conditions, Photoaging and Skin Cancers, a Review

Healthier life styles include increased outdoors time practicing sports and walking. This means increased exposure to the sun, leading to higher risk of sunburn, photoaging and skin cancer. In addition to topical barrier products, oral supplementations of various botanicals endowed with antioxidant activity are emerging as novel method of photoprotection. Polypodium leucotomos extract (PL, commercial name Fernblock^®, IFC Group, Spain) is a powerful antioxidant due to its high content of phenolic compounds. PL is administered orally, with proven safety, and it can also be used topically. Its mechanisms include inhibition of the generation and release of reactive oxygen species (ROS) by ultraviolet (UV) light. It also prevents UV- and ROS-induced DNA damage with inhibition of AP1 and NF-κB and protection of natural antioxidant enzyme systems. At the cellular level, PL decreases cellular apoptosis and necrosis mediated UV and inhibits abnormal extracellular matrix remodeling. PL reduces inflammation, prevents immunosuppression, activates tumor suppressor p53 and inhibits UV-induced cyclooxygenase-2 (COX-2) enzyme expression. In agreement with increased p53 activity, PL decreased UV radiation-induced cell proliferation. PL also prevents common deletions mitochondrial DNA damage induced by UVA, and MMP-1 expression induced Visible Light and Infrared Radiation. These cellular and molecular effects are reflected in inhibitions of carcinogenesis and photoaging.

Understanding the connection between platelet-activating factor, a UV-induced lipid mediator of inflammation, immune suppression and skin cancer

Lipid mediators of inflammation play important roles in several diseases including skin cancer, the most prevalent type of cancer found in the industrialized world. Ultraviolet (UV) radiation is a complete carcinogen and is the primary cause of skin cancer. UV radiation is also a potent immunosuppressive agent, and UV-induced immunosuppression is a well-known risk factor for skin cancer induction. An essential mediator in this process is the glyercophosphocholine 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine commonly referred to as platelet-activating factor (PAF). PAF is produced by keratinocytes in response to diverse stimuli and exerts its biological effects by binding to a single specific G-protein-coupled receptor (PAF-R) expressed on a variety of cells. This review will attempt to describe how this lipid mediator is involved in transmitting the immunosuppressive signal from the skin to the immune system, starting from its production by keratinocytes, to its role in activating mast cell migration in vivo, and to the mechanisms involved that ultimately lead to immune suppression. Recent findings related to its role in regulating DNA repair and activating epigenetic mechanisms, further pinpoint the importance of this bioactive lipid, which may serve as a critical molecular mediator that links the environment (UVB radiation) to the immune system and the epigenome.

Merkel cell carcinoma: emerging biology, current approaches, and future directions

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine cutaneous cancer that predominantly occurs in patients who are older, and is associated with a high rate of distant failure and mortality. Current management strategies that incorporate surgery and radiotherapy achieve high rates of locoregional control, but distant failure rates remain problematic, highlighting the need for new effective systemic therapies. Chemotherapy can achieve high response rates of limited duration in the metastatic setting, but its role in definitive management remains unproven. Recent developments in our knowledge about the biology of MCC have led to the identification of new potential therapeutic targets and treatments. A key finding has been the discovery that a human polyomavirus may be a causative agent. However, emerging data suggests that MCC may actually be two distinct entities, viral-associated and viral-negative MCC, which is likely to have implications for the management of MCC in the future and for the development of new treatments. In this review, we discuss recent discoveries about the biology of MCC, current approaches to management, and new therapeutic strategies that are being investigated.

Detection of UV-induced cyclobutane pyrimidine dimers by near-infrared spectroscopy and aquaphotomics

Ultraviolet (UV) radiation causes cellular DNA damage, among which cyclobutane pyrimidine dimers (CPDs) are responsible for a variety of genetic mutations. Although several approaches have been developed for detection of CPDs, conventional methods require time-consuming steps. Aquaphotomics, a new approach based on near-infrared spectroscopy (NIRS) and multivariate analysis that determines interactions between water and other components of the solution, has become an effective method for qualitative and quantitative parameters measurement in the solutions. NIR spectral patterns of UVC-irradiated and nonirradiated DNA solutions were evaluated using aquaphotomics for detection of UV-induced CPDs. Groups of UV-irradiated and nonirradiated DNA samples were classified (87.5% accuracy) by soft independent modeling of class analogy (SIMCA). A precise regression model calculated from NIR water spectral patterns based on UVC doses (r Val = 0.9457) and the concentration of cis-syn cyclobutane thymine dimers (cis-syn T<>Ts; r Val = 0.9993) was developed using partial least squares regression (PLSR), while taking advantage of water spectral patterns, particularly around 1400-1500 nm. Our results suggested that, in contrast to DNA, the formation of cis-syn T<>Ts increased the strongly hydrogen bonded water. Additionally, NIRS could qualitatively and quantitatively detect cis-syn T<>Ts in isolated DNA aqueous solutions upon UVC exposure.

Mechanisms of Photoaging and Cutaneous Photocarcinogenesis, and Photoprotective Strategies with Phytochemicals

Photoaging and photocarcinogenesis are primarily due to solar ultraviolet (UV) radiation, which alters DNA, cellular antioxidant balance, signal transduction pathways, immunology, and the extracellular matrix (ECM). The DNA alterations include UV radiation induced thymine-thymine dimers and loss of tumor suppressor gene p53. UV radiation reduces cellular antioxidant status by generating reactive oxygen species (ROS), and the resultant oxidative stress alters signal transduction pathways such as the mitogen-activated protein kinase (MAPK), the nuclear factor-kappa beta (NF-κB)/p65, the janus kinase (JAK), signal transduction and activation of transcription (STAT) and the nuclear factor erythroid 2-related factor 2 (Nrf2). UV radiation induces pro-inflammatory genes and causes immunosuppression by depleting the number and activity of the epidermal Langerhans cells. Further, UV radiation remodels the ECM by increasing matrixmetalloproteinases (MMP) and reducing structural collagen and elastin. The photoprotective strategies to prevent/treat photoaging and photocarcinogenesis include oral or topical agents that act as sunscreens or counteract the effects of UV radiation on DNA, cellular antioxidant balance, signal transduction pathways, immunology and the ECM. Many of these agents are phytochemical derivatives and include polyphenols and non-polyphenols. The flavonoids are polyphenols and include catechins, isoflavones, proanthocyanidins, and anthocyanins, whereas the non-flavonoids comprise mono phenolic acids and stilbenes. The natural sources of polyphenols include tea, cocoa, grape/wine, soy, pomegranate, and Polypodium leucotomos. The non-phenolic phytochemicals include carotenoids, caffeine and sulphoraphance (SFN). In addition, there are other phytochemical derivatives or whole extracts such as baicalin, flavangenol, raspberry extract, and Photomorphe umbellata with photoprotective activity against UVB radiation, and thereby carcinogenesis.

Current concept of photocarcinogenesis

Schematic pathway of UV induced inflammation and the formation of oxidative stress.

Preventive effects of ZPDC glycoprotein (24 kDa) on hepatotoxicity induced by mercury chloride in vitro and in vivo

Mercury is a potent environmental contaminant that exerts toxic effect on various vital organs in the human body. Recently, we isolated glycoprotein from Zanthoxylum piperitum DC (ZPDC), which has antioxidant and anticancer effects. In the present study, we determined the preventive effects of ZPDC glycoprotein on hepatic damage induced by mercury chloride (HgCl2 ). We evaluated the activities of lactate dehydrogenase (LDH), alanine aminotransferase (ALT), antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)], extracellular signal-regulated kinase (ERK)1/2, p38 mitogen-activated protein kinase (MAPK), cyclo-oxygenase (COX-2), inducible nitric oxide synthetase (iNOS), and activator protein (AP-1) and the quantitative expressions of nuclear factor E2-related factor (Nrf2), heme oxygenase (HO-1), metallothionein (MT) and reduced glutathione (GSH) in mercury-chloride-exposed (50 μM and 10 mg/kg body weight) primary cultured hepatocytes and ICR mice, using biochemical assays, radioactivity and immunoblot analysis. The results demonstrated that ZPDC glycoprotein decreased the levels of LDH, ALT, HO-1 and MT, whereas it increased the activities of hepatic antioxidant enzymes (SOD, CAT and GPx) and reduced GSH in mercury-chloride-exposed primary cultured hepatocytes. Also, it suppressed arachidonic acid release and expression of ERK, p38 MAPK, COX-2, iNOS, AP-1 and Nrf-2 in primary cultured hepatocytes and ICR mice exposed to mercury chloride. Collectively, ZPDC glycoprotein may have potential applications to prevent hepatotoxicity induced by mercury chloride.

Inhibitory effects of dietary Spirulina platensis on UVB-induced skin inflammatory responses and carcinogenesis

Reactive oxygen species produced in response to UVR are important in skin tumor development. We have previously reported that deficiency of the Ogg1 gene, encoding the repair enzyme for 8-oxo-7,8-dihydroguanine (8-oxoG), increases skin tumor incidence in mice upon repetitive UVB exposure and modulation of UVB-induced inflammatory response. Spirulina platensis is used as a human food supplement because it contains abundant nutritional and antioxidant components. Therefore, we investigated the inhibitory effects of S. platensis on UVB-induced skin tumor development in Ogg1 knockout-(KO) mice and the wild-type (WT) counterpart. Dietary S. platensis suppressed tumor induction and development in both genotypes compared with our previous data without S. platensis. Induction of erythema and ear swelling, one of the hallmarks of UVB-induced inflammatory responses, was suppressed in the skin of Ogg1-KO mice and albino hairless mice fed with dietary S. platensis. Compared with untreated mice, S. platensis-administered mice showed significantly reduced 8-oxoG formation in the skin after UVB exposure. Moreover, we found that S. platensis effectively downregulated the signal proteins p38 mitogen-activated protein kinase, stress-activated protein kinase/c-Jun N-terminal kinase, and extracellular signal-regulated kinase after UVB exposure especially in Ogg1-KO mice. Our results suggest that S. platensis exerts antitumor effects against UVB irradiation in the skin through its anti-inflammatory and antioxidant effects.

A novel mechanism of skin tumor promotion involving interferon-gamma (IFNγ)/signal transducer and activator of transcription-1 (Stat1) signaling

The current study was designed to explore the role of signal transducer and activator of transcription 1 (Stat1) during tumor promotion using the mouse skin multistage carcinogenesis model. Topical treatment with both 12-O-tetradecanoylphorbol-13-acetate (TPA) and 3-methyl-1,8-dihydroxy-9-anthrone (chrysarobin or CHRY) led to rapid phosphorylation of Stat1 on both tyrosine (Y701) and serine (S727) residues in epidermis. CHRY treatment also led to upregulation of unphosphorylated Stat1 (uStat1) at later time points. CHRY treatment also led to upregulation of interferon regulatory factor 1 (IRF-1) mRNA and protein, which was dependent on Stat1. Further analyses demonstrated that topical treatment with CHRY but not TPA upregulated interferon-gamma (IFNγ) mRNA in the epidermis and that the induction of both IRF-1 and uStat1 was dependent on IFNγ signaling. Stat1 deficient (Stat1(-/-) ) mice were highly resistant to skin tumor promotion by CHRY. In contrast, the tumor response (in terms of both papillomas and squamous cell carcinomas) was similar in Stat1(-/-) mice and wild-type littermates with TPA as the promoter. Maximal induction of both cyclooxygenase-2 and inducible nitric oxide synthase in epidermis following treatment with CHRY was also dependent on the presence of functional Stat1. These studies define a novel mechanism associated with skin tumor promotion by the anthrone class of tumor promoters involving upregulation of IFNγ signaling in the epidermis and downstream signaling through activated (phosphorylated) Stat1, IRF-1 and uStat1.

Ultraviolet light exposure stimulates HMGB1 release by keratinocytes

The primary cause of non-melanoma skin cancer is ultraviolet (UV) light from the sun. Many studies have demonstrated that cutaneous inflammation resulting from UV exposure is important for the development of skin cancer. In fact, anti-inflammatory drugs have been shown to be effective in preventing skin cancer in animal models and in clinical trials. One new class of inflammatory mediators that could regulate UV-induced inflammation and skin carcinogenesis is alarmins. Alarmins are endogenous molecules that act as potent pro-inflammatory mediators when they are released by cells or accumulate extracellularly. The purpose of the current studies was to examine the expression and release of the alarmin high mobility group box 1 (HMGB1) after acute and chronic UV irradiation. Acute UV exposure stimulated the release of HMGB1 in cultured human keratinocytes and epidermal keratinocytes in murine skin. HMGB1 release correlated with pro-inflammatory cytokine production in vitro and inflammatory cell infiltration in vivo. HMGB1 was also examined in tumors arising in chronically irradiated murine skin. HMGB1 protein expression in low grade, benign papillomas was similar to adjacent skin. However, HMGB1 staining was more widespread with a higher number of HMGB1-positive cells observed in high grade papillomas and malignant tumors. Overall, the data suggest that HMGB1 may be an important regulator of UV-induced cutaneous inflammation and tumor formation. Additional studies are needed to assess whether targeting HMGB1 would be a useful strategy to prevent tumors from developing in response to chronic UV exposure.

Ruthenium polypyridyl phototriggers: from beginnings to perspectives

Octahedral Ru(II) polypyridyl complexes constitute a superb platform to devise photoactive triggers capable of delivering entire molecules in a reliable, fast, efficient and clean way. Ruthenium coordination chemistry opens the way to caging a wide range of molecules, such as amino acids, nucleotides, neurotransmitters, fluorescent probes and genetic inducers. Contrary to other phototriggers, these Ru-based caged compounds are active with visible light, and can be photolysed even at 532 nm (green), enabling the use of simple and inexpensive equipment. These compounds are also active in the two-photon regime, a property that extends their scope to systems where IR light must be used to achieve high precision and penetrability. The state of the art and the future of ruthenium polypyridyl phototriggers are discussed, and several new applications are presented.

Melanin and urate act to prevent ultraviolet damage in the integument of the silkworm, Bombyx mori

The phenomenon that epidermal cells under the white stripes rather than black stripes contain many uric acid granules was found in larvae of several Lepidopteran species. However, the biological mechanism of this phenomenon is still unknown. In the present study, we take advantage of several silkworm (Bombyx mori) body color mutant strains to investigate the deposition patterns and biological mechanism of urate and melanin in the integuments of these mutant larvae. By imaging with transmission electron microscope, we found that there were some melanin granules in the larval cuticle in black body color mutant plain Black (p(B) ), but not in background strain plain (p) with white larval body color. In contrast, the larval epidermal cell of background strain had much more urate granules than that of black one. Furthermore, the uric acid content under the black stripes was significantly lower than that under the white stripes in a single individual of mottled stripe (p(S) ) with black and white stripes in each segment. Ultraviolet A (UVA) exposure experiments showed that the distinct oily (od) mutant individuals with translucent larval integument were more sensitive to the UVA damage than black body color mutant and background strain without any pigmentation in the larval cuticle. This is likely due to the absence of melanin granules and few urate granules in the integument of od mutant. Thus, both the deposited melanin granules in the cuticle and the abundant urate granules in the epidermis cells constitute effective barriers for the silkworm to resist UVA-induced damage.

UVA photoirradiation of benzo[a]pyrene metabolites: induction of cytotoxicity, reactive oxygen species, and lipid peroxidation

Benzo[ a]pyrene (BaP) is a prototype for studying carcinogenesis of polycyclic aromatic hydrocarbons (PAHs). We have long been interested in studying the phototoxicity of PAHs. In this study, we determined that metabolism of BaP by human skin HaCaT keratinocytes resulted in six identified phase I metabolites, for example, BaP trans-7,8-dihydrodiol (BaP t-7,8-diol), BaP t-4,5-diol, BaP t-9,10-diol, 3-hydroxybenzo[a]pyrene (3-OH-BaP), BaP (7,10/8,9)tetrol, and BaP (7/8,9,10)tetrol. The photocytotoxicity of BaP, 3-OH-BaP, BaP t-7,8-diol, BaP trans-7,8-diol- anti-9,10-epoxide (BPDE), and BaP (7,10/8,9)tetrol in the HaCaT keratinocytes was examined. When irradiated with 1.0 J/cm2 UVA light, these compounds when tested at doses of 0.1, 0.2, and 0.5 μM, all induced photocytotoxicity in a dose-dependent manner. When photoirradiation was conducted in the presence of a lipid (methyl linoleate), BaP metabolites, BPDE, and three related PAHs, pyrene, 7,8,9,10-tetrahydro-BaP trans-7,8-diol, and 7,8,9,10-tetrahydro-BaP trans-9,10-diol, all induced lipid peroxidation. The formation of lipid peroxides by BaP t-7,8-diol was inhibited by NaN3 and enhanced by deuterated methanol, which suggests that singlet oxygen may be involved in the generation of lipid peroxides. The formation of lipid hydroperoxides was partially inhibited by superoxide dismutase (SOD). Electron spin resonance spin trapping experiments indicated that both singlet oxygen and superoxide radical anion were generated from UVA photoirradiation of BPDE in a light dose responding manner.

Morpho-mechanical intestinal remodeling in type 2 diabetic GK rats--is it related to advanced glycation end product formation?

Little is known about the mechanisms for the biomechanical remodeling in diabetes. The histomorphology, passive biomechanical properties and expression of advanced glycation end product (N epsilon-(carboxymethyl) lysine, AGE) and its receptor (RAGE) were studied in jejunal segments from 8 GK diabetic rats (GK group) and 10 age-matched normal rats (Normal group). The mechanical test was done by using a ramp distension of fluid into the jejunal segments in vitro. Circumferential stress and strain were computed from the length, diameter and pressure data and from the zero-stress state geometry. AGE and RAGE were detected by immunohistochemistry staining. Linear regression analysis was done to study association between the glucose level and AGE/RAGE expression with the histomorphometric and biomechanical parameters. The blood glucose level, the jejunal weight per length, wall thickness, wall area and layer thickness significantly increased in the GK group compared with the Normal group (P<0.05, P<0.01 and P<0.001). The opening angle and absolute values of residual strain decreased whereas the circumferential stiffness of the jejunal wall increased in the GK group (P<0.05 and P<0.01). Furthermore, stronger AGE expression in the villi and crypt and RAGE expression in the villi were found in the GK group (P<0.05 and P<0.01). Most histomorphometric and biomechanical changes were associated with blood glucose level and AGE/RAGE expression. In conclusion, histomorphometric and biomechanical remodeling occurred in type 2 diabetic GK rats. The increasing blood glucose level and the increased AGE/RAGE expression were associated with the remodeling, indicating a causal relationship.

Molecular mechanisms of garlic-derived allyl sulfides in the inhibition of skin cancer progression

Skin cancer is a serious concern whose incidence is increasing at an alarming rate. Allyl sulfides—i.e., sulfur metabolites in garlic oil—have been demonstrated to have anticancer activity against several cancer types, although the mechanisms underlying these effects remain enigmatic. Our previous study showed that diallyl trisulfide (DATS) is more potent than mono- and disulfides against skin cancer. DATS inhibits cell growth of human melanoma A375 cells and basal cell carcinoma (BCC) cells by increasing the levels of intracellular reactive oxygen species (ROS) and DNA damage and by inducing G2/M arrest, endoplasmic reticulum (ER) stress, and mitochondria-mediated apoptosis, including the caspase-dependent and -independent pathways. This short review focuses on the molecular mechanisms of garlic-derived allyl sulfides on skin cancer prevention.

Epidermal expression of neuropilin 1 protects murine keratinocytes from UVB-induced apoptosis

Background

Neuropilin 1 (NRP1) is expressed on several cell types including neurons and endothelial cells, where it functions as an important regulator in development and during angiogenesis. As a cell surface receptor, NRP1 is able to bind to members of the VEGF family of growth factors and to secreted class 3 semaphorins. Neuropilin 1 is also highly expressed in keratinocytes, but the function of NRP1 in epidermal physiology and pathology is still unclear.

Methods and Results

To elucidate the role of NRP1 in skin in vivo we generated an epidermis-specific neuropilin 1 knock out mouse model by using the Cre-LoxP-System. Mice were viable and fertile and did not display any obvious skin or hair defects. After challenge with UVB irradiation, we found that deletion of epidermal NRP1 leads to increased rates of apoptosis both in vitro and in vivo. NRP1-deficient primary keratinocytes cultured in vitro showed significantly higher rates of apoptosis 24 hours after UVB. Likewise, there is a significant increase of active caspase 3 positive cells in the epidermis of Keratin 14-Cre-NRP1 (−/−) mice 24 hours after UVB irradiation. By Western Blot analysis we could show that NRP1 influences the cytosolic levels of Bcl-2, a pro-survival member of the Bcl-2 family. After UVB irradiation the amounts of Bcl-2 decrease in both protein extracts from murine epidermis and in NRP1-deficient keratinocytes in vitro, whereas wild type cells retain their Bcl-2 levels. Likewise, levels of phospho-Erk and Rac1 were lower in NRP1-knock out keratinocytes, whereas levels of pro-apoptotic p53 were higher.

Conclusion

NRP1 expression in keratinocytes is dispensable for normal skin development. Upon UVB challenge, NRP1 contributes to the prevention of keratinocyte apoptosis. This pro-survival function of NRP1 is accompanied by the maintenance of high levels of the antiapoptotic regulator Bcl-2 and by lower levels of pro-apoptotic p53.

Polypodium leucotomos decreases UV-induced epidermal cell proliferation and enhances p53 expression and plasma antioxidant capacity in hairless mice

A single dose of ultraviolet radiation (UVR) induces significant changes in blood and skin of hairless mice. Oral administration of a hydrophilic extract of the fern Polypodium leucotomos (PL, 300 mg/kg during 5 days before UVR and for two additional days after irradiation) modulates some of the effects of UVR. Most significantly, PL administration reduced the number of proliferating cells by 13%, increased the number of p53(+) cells by 63%, enhanced the antioxidant plasma capacity (ORAC) by 30% and reinforced the network of dermal elastic fibres. Western blot analysis of skin antioxidant-related enzymes failed to demonstrate significant changes caused by PL. Thus, the beneficial effect of PL likely owes to its antioxidant and anti-ROS properties rather than its modulation of the expression of endogenous antioxidant systems. These data provide mechanistic clues for its efficacy as a systemic photoprotective agent with antioxidant and anti-photo-ageing properties.

Silibinin is a potent sensitizer of UVA radiation-induced oxidative stress and apoptosis in human keratinocyte HaCaT cells

UVA radiation (315-400 nm), which constitutes ca 95% of the UV irradiation in natural sunlight reaching earth surface, is a major environmental risk factor associated with human skin cancer pathogenesis. UVA is an oxidizing agent that causes significant damage to cellular components through the release of reactive oxygen species (ROS) and leads to photoaging and photocarcinogenesis. Here we investigate the effect of silibinin, the flavonolignan from Silybum marianum, on UVA-induced ROS and cell death in human keratinocyte cell line HaCaT. In addition, the effect of silibinin on UVA-induced intracellular ROS-mediated endoplasmic reticulum (ER) stress was also analyzed. UVA irradiation resulted in ROS production and apoptosis in HaCaT cells in a dose-dependent manner, and the ROS levels and apoptotic index were found to be elevated significantly when the cells were treated with 75 μmsilibinin for 2 h before UVA exposure. When the cells were pretreated with 10 mmN-acetyl cysteine, the enhancement of UVA-induced apoptosis by silibinin was compromised. Furthermore, we found that silibinin enhances ER stress-mediated apoptosis in HaCaT cells by increasing the expression of CHOP protein. These results suggest that silibinin may be beneficial in the removal of UVA-damaged cells and the prevention of skin cancer.

Skin tumours induced by narrowband UVB have higher frequency of p53 mutations than tumours induced by broadband UVB independent of Ogg1 genotype

Different wavelengths of ultraviolet (UV) light have different promoting effects on skin carcinogenesis. Narrowband UVB (NB-UVB) has a single-peak wavelength of 311 nm and is widely used for treating skin diseases. Our previous work showed that, in comparison with conventional broadband UVB (BB-UVB), long-term exposure to NB-UVB induces higher frequency of skin cancer in mice, and it suggested that this is mediated through the formation of cyclobutane pyrimidine dimers (CPDs). To explore whether the frequency of p53 mutations in skin tumours correlates with CPD-induced mutations, we compared the frequency and types of p53 mutations between NB-UVB-induced and BB-UVB-induced malignant skin tumours produced in wild-type and Ogg1 knockout mice, which are deficient in repair of oxidative 8-oxoguanine (8-oxoG), a DNA damage mediated by reactive oxygen species (ROS). The frequency of p53 mutation was significantly higher in NB-UVB-induced than in BB-UVB-induced tumours in both wild-type and Ogg1 knockout mice. Most of the p53 mutations found were G:C → A:T transitions at dipyrimidine sites in both the NB-UVB- and BB-UVB-exposed groups. However, G:C → T:A mutations caused by 8-oxoG did not increase in Ogg1 knockout mice exposed to either NB-UVB or BB-UVB. Our results strongly suggest that NB-UVB induces highly malignant tumours caused by p53 dipyrimidine mutations through the formation of CPDs.

Cultivated ginseng suppresses ultraviolet B-induced collagenase activation via mitogen-activated protein kinases and nuclear factor κB/activator protein-1-dependent signaling in human dermal fibroblasts

Cultivated ginseng (CG) (Panax ginseng C.A. Meyer), an herb used in Korean herbal medicine, has been widely used in China and Japan to treat fatigue and to enhance resistance to many diseases. It contains many bioactive constituents, including various ginsenosides that are believed to have antioxidant, immunostimulatory, and antiaging activities. Previous studies have revealed that treatment with Panax ginseng is significantly associated with reduced photoaging, but the underlying mode of action has not been elucidated. In this study, we hypothesized that CG inhibits ultraviolet B (UVB)-induced collagenase activation through mitogen-activated protein kinases (MAPKs) and nuclear factor κB (NF-κB)/activator protein-1 (AP-1)-dependent signaling in human skin fibroblasts. HS68 cells were treated with CG, followed by irradiation with UVB. Those effects were assessed by semiquantitative polymerase chain reaction, Western blotting, and enzymic activity assays. We found that CG increased cell viability and inhibited the production of reactive oxygen species in HS68 cells exposed to UVB irradiation. Pretreatment of HS68 cells with CG inhibited UVB-induced production of matrix metalloproteinase (MMP) 1 and MMP-13. Western blot analysis further revealed that CG markedly suppressed the enhancement of collagen degradation in UVB-exposed HS68 cells. Cultivated ginseng also suppressed UVB-induced activation of NF-κB, c-Jun, and c-Fos and the phosphorylation of MAPKs, which are upstream modulators of NF-κB and AP-1. These results indicate that CG inhibits UVB-induced collagenolytic MMP production by interfering with MAPK/AP-1 and NF-κB signaling and thus may be useful in the prevention and treatment of skin photoaging.

Autocrine abscisic acid mediates the UV-B-induced inflammatory response in human granulocytes and keratinocytes

UV-B is an abiotic environmental stress in both plants and animals. Abscisic acid (ABA) is a phytohormone regulating fundamental physiological functions in plants, including response to abiotic stress. We previously demonstrated that ABA is an endogenous stress hormone also in animal cells. Here, we investigated whether autocrine ABA regulates the response to UV-B of human granulocytes and keratinocytes, the cells involved in UV-triggered skin inflammation. The intracellular ABA concentration increased in UV-B-exposed granulocytes and keratinocytes and ABA was released into the supernatant. The UV-B-induced production of NO and of reactive oxygen species (ROS), phagocytosis, and cell migration were strongly inhibited in granulocytes irradiated in the presence of a monoclonal antibody against ABA. Moreover, presence of the same antibody strongly inhibited release of NO, prostaglandin E2 (PGE(2)), and tumor necrosis factor-α (TNF-α) by UV-B irradiated keratinocytes. Lanthionine synthetase C-like protein 2 (LANCL2) is required for the activation of the ABA signaling pathway in human granulocytes. Silencing of LANCL2 in human keratinocytes by siRNA was accompanied by abrogation of the UV-B-triggered release of PGE(2), TNF-α, and NO and ROS production. These results indicate that UV-B irradiation induces ABA release from human granulocytes and keratinocytes and that autocrine ABA stimulates cell functions involved in skin inflammation.