Melanoma induction by ultraviolet A but not ultraviolet B radiation requires melanin pigment

Evaluation of the anti-aging potential of acetyl tripeptide-30 citrulline in cosmetics

Acetyl tripeptide-30 citrulline, a commercialized bio-active peptide, is widely used in anti-wrinkle formulations. Volunteer-based tests have demonstrated that topical application of products containing acetyl tripeptide-30 citrulline significantly reduces the visibility of stretch marks. However, there is still a lack of research dedicated to systematically and holistically evaluating its cosmetic properties and elucidating its mechanisms of action. In this study, we assessed the cosmetic potential of acetyl tripeptide-30 citrulline using human immortalized keratinocytes (HaCaT) and mouse embryonic fibroblasts (3T3). Our findings reveal that acetyl tripeptide-30 citrulline exhibits anti-inflammatory and antioxidant activities in skin cells, particularly effective against the inflammatory markers cyclooxygenase-2 (COX2), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6), and the extent of inhibition of reactive oxygen species (ROS) production ranged from 95 % to 340 %. Moreover, acetyl tripeptide-30 citrulline specifically up-regulates Collagen IV and down-regulates matrix metalloproteinase-9 (MMP9), enhances the expression of skin barrier proteins transglutaminase 1 (TGM1) and filaggrin (FLG), thereby demonstrating its reparative capabilities. Additionally, acetyl tripeptide-30 citrulline increases the expression of the water channel protein aquaporin 3 (AQP3), thus improving skin hydration function. These results substantiate the previously proclaimed cosmetic attributes of acetyl tripeptide-30 citrulline and support its efficacy as an anti-aging agent in dermatological applications.

Bacterial Cellulose as a UVB Filter to Protect the Skin Microbiota

Certain aerobic bacteria produce bacterial cellulose (BC) to protect themselves from UV radiation. Inspired by this natural function, the UV-filtering capacity of wet BC film (BC) and dried BC (BC-Dried) is evaluated and it is concluded that both samples hardly filter UVA, but filter UVB to some extent, especially BC-Dried. Moreover, this filtering capacity does not diminish but significantly increases with time, with efficiencies in the 145-160 min time range equal to or greater than most UV filters of the market. This increase in efficiency is due to the fact that the BC structure is modified by prolonged exposure to UVB radiation. Specifically, UVB causes sintering of the cellulose fibers, making the structure denser and increasing its reflection and scattering of UVB radiation. Remarkably, this UVB filtering ability of BC allows it to protect key skin probiotics, Lactobacillus fermentum (L. fermentum) and Cutibacterium acnes (C. acnes), against UVB damage. While the protection of healthy skin microbiota is not currently a regulatory requirement for sunscreens with UV filters, it may become a key differentiator for future UV filters given the increasing evidence on the role of skin microbiota in health.

Association between arsenic exposure and melanoma: a meta-analysis

BACKGROUND

Melanoma is a highly malignant tumor. Moreover, its prevalence is increasing at a rapid rate year after year. Currently, UV light is the leading cause of melanoma, although numerous other risk factors exist, including arsenic. The link between arsenic and the likelihood of developing melanoma has long been debated. As a result, we conducted a meta-analysis of the available data to investigate the association between arsenic exposure and melanoma.

METHODS

We identified seven non-randomized controlled studies with 41,949 participants by searching the Chinese CNKI, Embase, PubMed, and Cochrane Library databases. We then used random-effects or fixed-effects models to evaluate the pooled odds ratios (OR) and their 95% confidence intervals (CI). Subgroup analyses were also carried out with different included regions.

RESULTS

Participants in the study who were exposed to arsenic had a somewhat higher chance of developing melanoma than those who were not (OR = 1.47, 95% CI 1.01-2.13). A subgroup analysis was also carried out for the US region, and the findings were not statistically significant (OR = 1.40, 95% CI 0.94-2.07).

CONCLUSION

This meta-analysis shows that arsenic exposure relates to an increased risk of melanoma.

Oxidative State in Cutaneous Melanoma Progression: A Question of Balance

Reactive oxygen species (ROS) are highly bioactive molecules involved not only in tissue physiology but also in the development of different human conditions, including premature aging, cardiovascular pathologies, neurological and neurodegenerative disorders, inflammatory diseases, and cancer. Among the different human tumors, cutaneous melanoma, the most aggressive and lethal form of skin cancer, is undoubtedly one of the most well-known "ROS-driven tumor", of which one of the main causes is represented by ultraviolet (UV) rays' exposure. Although the role of excessive ROS production in melanoma development in pro-tumorigenic cell fate is now well established, little is known about its contribution to the progression of the melanoma metastatic process. Increasing evidence suggests a dual role of ROS in melanoma progression: excessive ROS production may enhance cellular growth and promote therapeutic resistance, but at the same time, it can also have cytotoxic effects on cancer cells, inducing their apoptosis. In this context, the aim of the present work was to focus on the relationship between cell redox state and the signaling pathways directly involved in the metastatic processes. In addition, oxidative or antioxidant therapeutic strategies for metastatic melanoma were also reviewed and discussed.

Nature-Inspired Intelligent Computing: A Comprehensive Survey

Nature, with its numerous surprising rules, serves as a rich source of creativity for the development of artificial intelligence, inspiring researchers to create several nature-inspired intelligent computing paradigms based on natural mechanisms. Over the past decades, these paradigms have revealed effective and flexible solutions to practical and complex problems. This paper summarizes the natural mechanisms of diverse advanced nature-inspired intelligent computing paradigms, which provide valuable lessons for building general-purpose machines capable of adapting to the environment autonomously. According to the natural mechanisms, we classify nature-inspired intelligent computing paradigms into 4 types: evolutionary-based, biological-based, social-cultural-based, and science-based. Moreover, this paper also illustrates the interrelationship between these paradigms and natural mechanisms, as well as their real-world applications, offering a comprehensive algorithmic foundation for mitigating unreasonable metaphors. Finally, based on the detailed analysis of natural mechanisms, the challenges of current nature-inspired paradigms and promising future research directions are presented.

Innate Immune Cells in Melanoma: Implications for Immunotherapy

The innate immune system, composed of neutrophils, basophils, eosinophils, myeloid-derived suppressor cells (MDSCs), macrophages, dendritic cells (DCs), mast cells (MCs), and innate lymphoid cells (ILCs), is the first line of defense. Growing evidence demonstrates the crucial role of innate immunity in tumor initiation and progression. Several studies support the idea that innate immunity, through the release of pro- and/or anti-inflammatory cytokines and tumor growth factors, plays a significant role in the pathogenesis, progression, and prognosis of cutaneous malignant melanoma (MM). Cutaneous melanoma is the most common skin cancer, with an incidence that rapidly increased in recent decades. Melanoma is a highly immunogenic tumor, due to its high mutational burden. The metastatic form retains a high mortality. The advent of immunotherapy revolutionized the therapeutic approach to this tumor and significantly ameliorated the patients' clinical outcome. In this review, we will recapitulate the multiple roles of innate immune cells in melanoma and the related implications for immunotherapy.

Physiological Roles of Eumelanin- and Melanogenesis-Associated Diseases: A Look at the Potentialities of Engineered and Microbial Eumelanin in Clinical Practice

This paper aims to highlight the physiological actions exerted by eumelanin present in several organs/tissues of the human body and to rationalise the often conflicting functional roles played by this biopolymer on the basis of its peculiar properties. Besides pigmentary disorders, a growing number of organ injuries and degenerative pathologies are presently ascribed to the modification of physiological eumelanin levels in terms of alterations in its chemical/structural features, and of a partial loss or uneven distribution of the pigment. The present review analyses the more recent research dedicated to the physiological and pathological actions of eumelanin and provides an insight into some melanogenesis-associated diseases of the skin, eye, ear, and brain, including the most significant neurodegenerative disorders. Also described are the potentialities of therapies based on the localised supply of exogeneous EU and the opportunities that EU produced via synthetic biology offers in order to redesign therapeutical and diagnostic applications.

Melanin: Nature's 4th bioorganic polymer

The pigments known as the melanins are widely recognized for their responsibility in the coloration of human skin, eyes, hair, and minimising the harmful effects of solar ultraviolet radiation. But specialists are aware that the melanins are present in all living kingdoms, barring viruses, and have functionality that extends beyond neutralizing ionising radiation. The ubiquitous presence of melanin in almost all human organs, recognized in recent years, as well as the presence of melanin in organisms that are evolutionarily distant from each other, indicate the fundamental importance of this class of material for all life forms. In this review, we argue for the need to accept melanins as the fourth primordial class of biological polymers, along with nucleic acids, proteins and polysaccharides. We consistently compare the properties of these canonical biological polymers with the properties of melanin and highlight key features that fundamentally distinguish melanins, their function and its mysteries.

The metabolism of melanin synthesis-From melanocytes to melanoma

Melanin synthesis involves the successful coordination of metabolic pathways across multiple intracellular compartments including the melanosome, mitochondria, ER/Golgi, and cytoplasm. While pigment production offers a communal protection from UV damage, the process also requires anabolic and redox demands that must be carefully managed by melanocytes. In this report we provide an updated review on melanin metabolism, including recent data leveraging new techniques, and technologies in the field of metabolism. We also discuss the many aspects of melanin synthesis that intersect with metabolic pathways known to impact melanoma phenotypes and behavior. By reviewing the metabolism of melanin synthesis, we hope to highlight outstanding questions and opportunities for future research that could improve patient outcomes in pigmentary and oncologic disease settings.

Malignant Melanoma: An Overview, New Perspectives, and Vitamin D Signaling

Melanoma, originating through malignant transformation of melanin-producing melanocytes, is a formidable malignancy, characterized by local invasiveness, recurrence, early metastasis, resistance to therapy, and a high mortality rate. This review discusses etiologic and risk factors for melanoma, diagnostic and prognostic tools, including recent advances in molecular biology, omics, and bioinformatics, and provides an overview of its therapy. Since the incidence of melanoma is rising and mortality remains unacceptably high, we discuss its inherent properties, including melanogenesis, that make this disease resilient to treatment and propose to use AI to solve the above complex and multidimensional problems. We provide an overview on vitamin D and its anticancerogenic properties, and report recent advances in this field that can provide solutions for the prevention and/or therapy of melanoma. Experimental papers and clinicopathological studies on the role of vitamin D status and signaling pathways initiated by its active metabolites in melanoma prognosis and therapy are reviewed. We conclude that vitamin D signaling, defined by specific nuclear receptors and selective activation by specific vitamin D hydroxyderivatives, can provide a benefit for new or existing therapeutic approaches. We propose to target vitamin D signaling with the use of computational biology and AI tools to provide a solution to the melanoma problem.

Cyclic AMP-regulatory element-binding protein: a novel UV-targeted transcription factor in skin cancer

Common therapeutics in relation to melanoma and non-melanoma cancers include the use of kinase inhibitors. The long-term benefits of kinases, however, are limited by development of drug resistance. An alternative approach for treatment would be to focus on transcription factors. Cyclic AMP-regulatory element-binding protein (CREB) is a transcription factor that is commonly overactivated or overexpressed in many different cancers including skin cancer. Ultraviolet radiation (UVR), one of the main causes of skin cancer, can activate CREB in both melanocytes and keratinocytes. In addition, CREB has been found to be activated in skin cancers. Considering the prominent role that CREB plays in skin cancers, the studies reviewed herein raise the possibility of CREB as a potential prognostic and diagnostic marker of skin cancer and a novel target for therapeutic intervention.

Unaddressed Challenges in the Treatment of Cutaneous Melanoma?

Background and Objectives: While the management of noninvasive cutaneous melanoma (CM) is typically limited to a secondary excision to reduce recurrence risk and periodic follow-up, treating patients with advanced melanoma presents ongoing challenges. Materials and Methods: This review provides a comprehensive examination of both established and emerging pharmacologic strategies for advanced CM management, offering an up-to-date insight into the current therapeutic milieu. The dynamic landscape of advanced CM treatment is explored, highlighting the efficacy of immune checkpoint inhibitors and targeted therapies, either in monotherapy or combination regimens. Additionally, ongoing investigations into novel treatment modalities are thoroughly discussed, reflecting the evolving nature of melanoma management. Results: The therapeutic landscape for melanoma management is undergoing significant transformation. Although various treatment modalities exist, there remains a critical need for novel therapies, particularly for certain stages of melanoma or cases resistant to current options. Conclusions: Consequently, further studies are warranted to identify new treatment avenues and optimize the utilization of existing drugs.

Stochastic modelling of single-cell gene expression adaptation reveals non-genomic contribution to evolution of tumor subclones

Cancer progression is an evolutionary process driven by the selection of cells adapted to gain growth advantage. We present the first formal study on the adaptation of gene expression in subclonal evolution. We model evolutionary changes in gene expression as stochastic Ornstein-Uhlenbeck processes, jointly leveraging the evolutionary history of subclones and single-cell expression data. Applying our model to sublines derived from single cells of a mouse melanoma revealed that sublines with distinct phenotypes are underlined by different patterns of gene expression adaptation, indicating non-genetic mechanisms of cancer evolution. Interestingly, sublines previously observed to be resistant to anti-CTLA-4 treatment showed adaptive expression of genes related to invasion and non-canonical Wnt signaling, whereas sublines that responded to treatment showed adaptive expression of genes related to proliferation and canonical Wnt signaling. Our results suggest that clonal phenotypes emerge as the result of specific adaptivity patterns of gene expression.

Integrative analysis of RNA-sequencing and microarray for the identification of adverse effects of UVB exposure on human skin

Background

Ultraviolet B (UVB) from sunlight represents a major environmental factor that causes toxic effects resulting in structural and functional cutaneous abnormalities in most living organisms. Although numerous studies have indicated the biological mechanisms linking UVB exposure and cutaneous manifestations, they have typically originated from a single study performed under limited conditions.

Methods

We accessed all publicly accessible expression data of various skin cell types exposed to UVB, including skin biopsies, keratinocytes, and fibroblasts. We performed biological network analysis to identify the molecular mechanisms and identify genetic biomarkers.

Results

We interpreted the inflammatory response and carcinogenesis as major UVB-induced signaling alternations and identified three candidate biomarkers (IL1B, CCL2, and LIF). Moreover, we confirmed that these three biomarkers contribute to the survival probability of patients with cutaneous melanoma, the most aggressive and lethal form of skin cancer.

Conclusion

Our findings will aid the understanding of UVB-induced cutaneous toxicity and the accompanying molecular mechanisms. In addition, the three candidate biomarkers that change molecular signals due to UVB exposure of skin might be related to the survival rate of patients with cutaneous melanoma.

Photosensibilisierende Antihypertensiva und das Hautkrebsrisiko bei postmenopausalen Frauen: Photosensitizing antihypertensive medication and risk of skin cancer among postmenopausal women

Hintergrund

Es gibt nur wenige prospektive Studien, die die Dosis‐Wirkungs‐Beziehung zwischen der Anwendung einiger photosensibilisierender Antihypertensiva und Hautkrebs untersucht haben.

Patienten und Methodik

Anhand prospektiver Daten aus der Women's Health Initiative Observational Study untersuchten wir den Zusammenhang zwischen der Anwendung von Antihypertensiva und dem Risiko für nicht melanozytären Hautkrebs (NMSC) und dem Melanom bei postmenopausalen Frauen im Alter von 50–79 Jahren (n = 64 918). Dabei wurden multivariable Cox‐Regressionsmodelle (Proportional‐Hazard‐Modelle) verwendet und Hazard Ratios (HR) sowie 95%‐Konfidenzintervalle (KI) berechnet.

Ergebnisse

8777 NMSC und 1227 Melanom‐Fälle wurden beobachtet. Die Anwendung von Antihypertensiva (HR [95%‐KI]: 1,12 [1,07–1,18]), ACE‐Hemmern (1,09 [1,01–1,18]), Kalziumkanalblockern (1,13 [1,05–1,22]), Diuretika (1,20 [1,12–1,27]), Schleifendiuretika (1,17 [1,07–1,28]) und Thiaziden (1,17 [1,03–1,33]) war jeweils mit einem erhöhten NMSC‐Risiko assoziiert. Das NMSC‐Risiko stieg linear mit der Anwendung mehrerer Antihypertensiva (p‐Trend = 0,02) und mit zunehmender Anwendungsdauer (p‐Trend < 0,01) an. Antihypertensiva (1,15 [1,00–1,31]), Angiotensin‐II‐Rezeptorblocker (1,82 [1,05–3,15]) und Diuretika (1,34 [1,13–1,59]) waren jeweils mit einem erhöhten Melanomrisiko assoziiert. Zwischen der Anwendung von Antihypertensiva und der Melanom‐Inzidenz wurde eine Effektmodifikation durch Exposition gegenüber Sonnenlicht‐Exposition beobachtet (p‐Interaktion = 0,02).

Schlussfolgerungen

Die Anwendung von Antihypertensiva allgemein und einiger einzelner Klassen von Antihypertensiva ging mit einer erhöhten Inzidenz von NMSC und Melanomen einher, wobei eine Dosis‐Wirkungs‐Beziehung bestand.

Photosensitizing antihypertensive medication and risk of skin cancer among postmenopausal women

BACKGROUND

Few prospective studies exist with an evaluation of a dose-response relationship between use of some photosensitizing antihypertensive medications and skin cancer.

PATIENT AND METHODS

We used prospective data from the Women's Health Initiative Observational Study to investigate the association between antihypertensive use and risk of non-melanoma skin cancer (NMSC) and melanoma in postmenopausal women aged 50-79 years at baseline (n  =  64,918). Multivariable Cox proportional hazards regression models were used and hazard ratios (HRs) and 95 confidence intervals (CIs) were calculated.

RESULTS

8,777 NMSC and 1,227 melanoma cases were observed. Use of antihypertensives (HR [95% CI]: 1.12 [1.07-1.18]), ACE inhibitors (1.09 [1.01-1.18]), calcium channel blockers (1.13 [1.05-1.22]), diuretics (1.20 [1.12-1.27]), loop diuretics (1.17 [1.07-1.28]), and thiazides (1.17 [1.03-1.33]) were each associated with higher NMSC risk. NMSC risk linearly increased with use of multiple antihypertensives (p-trend  =  0.02) and with longer duration of use (p-trend < 0.01). Antihypertensives (1.15 [1.00-1.31]), angiotensin-II receptor blockers (1.82 [1.05-3.15]), and diuretics (1.34 [1.13-1.59]) were each associated with elevated melanoma risk. Effect modification by solar radiation exposure was found between antihypertensive use and incidence of melanoma (p-interaction  =  0.02).

CONCLUSIONS

Use of antihypertensives overall, and several individual classes thereof, were associated with higher incidence of NMSC and melanoma with dose-response relationship.

Skin Protection by Carotenoid Pigments

Sunlight, despite its benefits, can pose a threat to the skin, which is a natural protective barrier. Phototoxicity caused by overexposure, especially to ultraviolet radiation (UVR), results in burns, accelerates photoaging, and causes skin cancer formation. Natural substances of plant origin, i.e., polyphenols, flavonoids, and photosynthetic pigments, can protect the skin against the effects of radiation, acting not only as photoprotectors like natural filters but as antioxidant and anti-inflammatory remedies, alleviating the effects of photodamage to the skin. Plant-based formulations are gaining popularity as an attractive alternative to synthetic filters. Over the past 20 years, a large number of studies have been published to assess the photoprotective effects of natural plant products, primarily through their antioxidant, antimutagenic, and anti-immunosuppressive activities. This review selects the most important data on skin photodamage and photoprotective efficacy of selected plant carotenoid representatives from in vivo studies on animal models and humans, as well as in vitro experiments performed on fibroblast and keratinocyte cell lines. Recent research on carotenoids associated with lipid nanoparticles, nanoemulsions, liposomes, and micelles is reviewed. The focus was on collecting those nanomaterials that serve to improve the bioavailability and stability of carotenoids as natural antioxidants with photoprotective activity.

Risk of Melanoma and Non-Melanoma Skin Cancer in Patients with Psoriasis and Psoriatic Arthritis Treated with Targeted Therapies: A Systematic Review and Meta-Analysis

Targeted therapies represent major advancements in the treatment of chronic skin conditions such as psoriasis. While previous studies have shown an increased risk of melanoma and non-melanoma skin cancer (NMSC) in patients receiving TNF-α inhibitors, the risks associated with newer biologics (IL-12/23 inhibitors, IL-23 inhibitors, IL-17 inhibitors) and Janus kinase (JAK) inhibitors remain less known. Using a systematic and meta-analytical approach, we aimed to summarize the currently available literature concerning skin cancer risk in patients treated with targeted therapies. The MEDLINE/PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched to find studies reporting the incidence rates (IR) of melanoma and NMSC in patients with psoriasis and psoriatic arthritis treated with biologics or JAK inhibitors. Nineteen studies were included in the analysis with a total of 13,739 patients. The overall IR of melanoma was 0.08 (95% CI, 0.05-0.15) events per 100 PYs and the overall IR of NMSC was 0.45 (95% CI, 0.33-0.61) events per 100 PYs. The IRs of melanoma were comparable across patients treated with IL-17 inhibitors, IL-23 inhibitors, and JAK inhibitors, while the IRs of NMSC were higher in patients treated with JAK inhibitors than in those treated with biologics. Prospective, long-term cohort studies are required to reliably assess the risks associated with novel targeted therapies.

Prognostic models based on lymph node density for primary gastrointestinal melanoma: a SEER population-based analysis

OBJECTIVE

This study aimed to construct prognostic models to predict the overall survival (OS) and cancer-specific survival (CSS) of patients with primary gastrointestinal melanoma (PGIM).

DESIGN

An observational and retrospective study.

SETTING

Data were obtained from the Surveillance, Epidemiology and End Results (SEER) programme database, encompassing a broad geographical and demographic spectrum of patients across the USA.

PARTICIPANTS

A total of 991 patients diagnosed with PGIM were included in this study.

METHODS

A total of 991 patients with PGIM were selected from the SEER database. They were further divided into a training cohort and a validation cohort. Independent prognostic factors were identified by Cox regression analysis. Two prognostic models were constructed based on the results of multivariable Cox regression analysis. The concordance index (C-index) and area under the time-dependent receiver operating characteristic curve (time-dependent AUC) were used to evaluate the discriminative ability. Calibration curves were plotted to evaluate the agreement between the probability as predicted by the models and the actual probability. Risk stratification was developed given the model.

RESULTS

By the multivariable Cox regression analysis, we identified four independent risk factors (age, stage, lymph node density and surgery) for OS, and three independent risk factors (stage, lymph node density and surgery) for CSS, which were used to construct prognostic models. C-index, time-dependent AUC, calibration curves and Kaplan-Meier curves of risk stratification indicated that these two models had good discriminative ability, predictive ability as well as clinical value.

CONCLUSIONS

The prognostic models of OS and CSS had satisfactory accuracy and were of clinical value in evaluating the prognosis of patients with PGIM.

A Side-by-Side Comparison of Wildtype and Variant Melanocortin 1 Receptor Signaling with Emphasis on Protection against Oxidative Damage to DNA

Common variants of the MC1R gene coding the α-melanocyte stimulating hormone receptor are associated with light skin, poor tanning, blond or red hair, and increased melanoma risk, due to pigment-dependent and -independent effects. This complex phenotype is usually attributed to impaired activation of cAMP signaling. However, several MC1R variants show significant residual coupling to cAMP and efficiently activate mitogenic extracellular signal-regulated kinase 1 and 2 (ERK1/2) signaling. Yet, residual signaling and the key actions of wildtype and variant MC1R have never been assessed under strictly comparable conditions in melanocytic cells of identical genetic background. We devised a strategy based on CRISPR-Cas9 knockout of endogenous MC1R in a human melanoma cell line wildtype for BRAF, NRAS and NF1, followed by reconstitution with epitope-labeled MC1R constructs, and functional analysis of clones expressing comparable levels of wildtype, R151C or D294H MC1R. The proliferation rate, shape, adhesion, motility and sensitivity to oxidative DNA damage were compared. The R151C and D294H RHC variants displayed impaired cAMP signaling, intracellular stability similar to the wildtype, triggered ERK1/2 activation as effectively as the wildtype, and afforded partial protection against oxidative DNA damage, although less efficiently than the wildtype. Therefore, common melanoma-associated MC1R variants display biased signaling and significant genoprotective activity.

Dual Action of Curcumin as an Anti- and Pro-Oxidant from a Biophysical Perspective

Curcumin, a natural polyphenol widely used as a spice, colorant and food additive, has been shown to have therapeutic effects against different disorders, mostly due to its anti-oxidant properties. Curcumin also reduces the efficiency of melanin synthesis and affects cell membranes. However, curcumin can act as a pro-oxidant when blue light is applied, since upon illumination it can generate singlet oxygen. Our review aims to describe this dual role of curcumin from a biophysical perspective, bearing in mind its concentration, bioavailability-enhancing modifications and membrane interactions, as well as environmental conditions such as light. In low concentrations and without irradiation, curcumin shows positive effects and can be recommended as a beneficial food supplement. On the other hand, when used in excess or irradiated, curcumin can be toxic. Therefore, numerous attempts have been undertaken to test curcumin as a potential photosensitizer in photodynamic therapy (PDT). At that point, we underline that curcumin-based PDT is limited to the treatment of superficial tumors or skin and oral infections due to the weak penetration of blue light. Additionally, we conclude that an increase in curcumin bioavailability through the using nanocarriers, and therefore its concentration, as well as its topical use if skin is exposed to light, may be dangerous.

Cutaneous interaction with visible light: What do we know?

Visible light has been used therapeutically in dermatology for years for a variety of cosmetic and medical indications, including skin rejuvenation and the treatment of inflammatory and neoplastic conditions, among others. Until recently, visible light was thought to be relatively inert compared to its spectral neighbors, ultraviolet and infrared radiation. However, recent literature has described the ability of visible light to cause erythema in light skin and pigmentary changes in individuals with darker skin types. Concern surrounding its potentially damaging cutaneous effects has been raised in both the medical community and social media outlets. In this article, we provide an evidenced-based review describing what is currently known about visible light, focusing on its role in dermatologic diseases including disorders of hyperpigmentation such as melasma and postinflammatory hyperpigmentation.

Endogenous Photosensitizers in Human Skin

Endogenous photosensitizers play a critical role in both beneficial and harmful light-induced transformations in biological systems. Understanding their mode of action is essential for advancing fields such as photomedicine, photoredox catalysis, environmental science, and the development of sun care products. This review offers a comprehensive analysis of endogenous photosensitizers in human skin, investigating the connections between their electronic excitation and the subsequent activation or damage of organic biomolecules. We gather the physicochemical and photochemical properties of key endogenous photosensitizers and examine the relationships between their chemical reactivity, location within the skin, and the primary biochemical events following solar radiation exposure, along with their influence on skin physiology and pathology. An important take-home message of this review is that photosensitization allows visible light and UV-A radiation to have large effects on skin. The analysis presented here unveils potential causes for the continuous increase in global skin cancer cases and emphasizes the limitations of current sun protection approaches.

The Selective Cytotoxicity of Quercus Brantii Lindl. Galls on A375 and SK-MEL-3 Human Malignant Melanoma Cell Lines

This study aimed to find out the mechanism of cytotoxic effects of galls of Quercus Brantii on A375 and SK-MEL-3 melanoma and AGO-1522 normal human fibroblast cell lines for the first time. Therefore, cell viability and cytotoxic activities were evaluated. Furthermore, ROS formation, lipid peroxidation, and release of cytochrome-c were also assessed. The results revealed that the extract of these galls at a concentration of 0.05 mg/ml significantly (P<0.001) increased cytotoxicity, ROS formation, TBARS formation, and cytochrome-c release in A375 and SK-MEL-3 melanoma cell lines compared to AGO-1522 normal human fibroblast. These results demonstrated that these galls can be considered a promising candidate which acts in synergy with anticancer agents used in the clinical treatment of human malignant melanoma.

Prominent Roles and Conflicted Attitudes of Eumelanin in the Living World

Eumelanin, a macromolecule widespread in all the living world and long appreciated for its protective action against harmful UV radiation, is considered the beneficial component of the melanin family (ευ means good in ancient Greek). This initially limited picture has been rather recently extended and now includes a variety of key functions performed by eumelanin in order to support life also under extreme conditions. A lot of still unexplained aspects characterize this molecule that, in an evolutionary context, survived natural selection. This paper aims to emphasize the unique characteristics and the consequent unusual behaviors of a molecule that still holds the main chemical/physical features detected in fossils dating to the late Carboniferous. In this context, attention is drawn to the duality of roles played by eumelanin, which occasionally reverses its functional processes, switching from an anti-oxidant to a pro-oxidant behavior and implementing therefore harmful effects.

Photoreactivity and phototoxicity of experimentally photodegraded hair melanosomes from individuals of different skin phototypes

Even though melanin is commonly viewed as natural photoprotectant, the pigment demonstrates residual photoreactivity, which under certain conditions could contribute to UVA-dependent melanomagenesis. Skin melanin is constantly exposed to external stressors, including solar radiation, which could induce photodegradation of the pigment. Although photodegradation of melanin pigments was studied in synthetic models and RPE melanosomes, photochemical and photobiological effects of experimental photodegradation of human skin melanin of different chemical composition remain unknown. In this work, melanosomes isolated from hair of individuals of different skin phototypes (I-III, V) were exposed to high-intensity violet light and its impact on physical and chemical properties of the pigments were analyzed using electron paramagnetic resonance (EPR), spectrophotometry and dynamic light scattering (DLS). Photoreactivity of photodegraded melanins was examined by EPR oximetry, EPR spin-trapping and time-resolved singlet oxygen phosphorescence. Antioxidant potential of the pigments was measured using the EPR DPPH assay. Cellular effect of the exposure of melanosome-loaded HaCaT cells to UV-Vis light was determined by MTT assay, JC-10 assay, and iodometric assay. The data revealed that experimental photodegradation increased photoreactivity of natural melanins, while decreasing their antioxidant capacity. Photodegraded melanin was responsible for higher cell death, a decrease in mitochondrial membrane potential and elevated levels of lipid hydroperoxides.

Cell-intrinsic melanin fails to protect melanocytes from ultraviolet-mutagenesis in the absence of epidermal melanin

Melanin is a free-radical scavenger, antioxidant, and broadband absorber of ultraviolet (UV) radiation which protects the skin from environmental carcinogenesis. However, melanin synthesis and UV-induced reactive melanin species are also implicated in melanocyte genotoxicity. Here, we attempted to reconcile these disparate functions of melanin using a UVB-sensitive, NRAS-mutant mouse model, TpN. We crossed TpN mice heterozygous for an inactivating mutation in Tyrosinase to produce albino and black littermates on a C57BL/6J background. These animals were then exposed to a single UVB dose on postnatal day three when keratinocytes in the skin have yet to be melanized. Approximately one-third (35%) of black mice were protected from UVB-accelerated tumor formation. However, melanoma growth rates, tumor mutational burdens, and gene expression profiles were similar in melanomas from black and albino mice. Skin from albino mice contained more cyclobutane pyrimidine dimer (CPD) positive cells than black mice 1-h post-irradiation. However, this trend gradually reversed over time with CPDs becoming more prominent in black than albino melanocytes at 48 h. These results show that in the absence of epidermal pigmentation, melanocytic melanin limits the tumorigenic effects of acute UV exposure but fails to protect melanocytes from UVB-induced mutagenesis.

Interferon-gamma signaling promotes melanoma progression and metastasis

Interferon-gamma (IFNG) has long been regarded as the flag-bearer for the anti-cancer immunosurveillance mechanisms. However, relatively recent studies have suggested a dual role of IFNG, albeit there is no direct experimental evidence for its potential pro-tumor functions. Here we provide in vivo evidence that treatment of mouse melanoma cell lines with Ifng enhances their tumorigenicity and metastasis in lung colonization allograft assays performed in immunocompetent syngeneic host mice, but not in immunocompromised host mice. We also show that this enhancement is dependent on downstream signaling via Stat1 but not Stat3, suggesting an oncogenic function of Stat1 in melanoma. The experimental results suggest that melanoma cell-specific Ifng signaling modulates the tumor microenvironment and its pro-tumorigenic effects are partially dependent on the γδ T cells, as Ifng-enhanced tumorigenesis was inhibited in the TCR-δ knockout mice. Overall, these results show that Ifng signaling may have tumor-promoting effects in melanoma by modulating the immune cell composition of the tumor microenvironment.

Probing photoprotection properties of lipophilic chain conjugated thiourea-aryl group molecules to attenuate ultraviolet-A induced cellular and DNA damages

Ultraviolet-A (UVA) radiation is a major contributor to reactive oxygen species (ROS), reactive nitrite species (RNS), inflammation, and DNA damage, which causes photoaging and photocarcinogenesis. This study aimed to evaluate the UVA protective potential of lipophilic chain conjugated thiourea-substituted aryl group molecules against UVA-induced cellular damages in human dermal fibroblasts (BJ cell line). We tested a series of nineteen (19) molecules for UVA photoprotection, from which 2',5'-dichlorophenyl-substituted molecule DD-04 showed remarkable UVA protection properties compared to the reference (benzophenone). The results indicate that DD-04 significantly reduced intracellular ROS and nitric oxide (NO) as compared to the UVA-irradiated control (p < 0.001). Moreover, the compound DD-04 showed anti-inflammatory activity as it significantly reduced the levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) pro-inflammatory cytokines produced by THP-1 (human monocytic) cells (p < 0.05). DNA damage was also prevented by DD-04 treatment in the presence of UVA. It was observed that DD-04 significantly reduced the number of cyclobutane pyrimidine dimers (CPDs) when compared to the UVA-irradiated control (p < 0.001). Finally, the DNA strand breaks were checked and a single intact DNA band was seen upon treatment with DD-04 in the presence of UVA. In conclusion, DD-04 can be considered a potential candidate UVA filter due to its photoprotective potential.

Ultraviolet A radiation exposure and melanoma: a review

The incidence of cutaneous melanoma has been increasing worldwide, and melanoma disproportionately contributes to skin cancer mortality. The pathogenesis of melanoma involves genetic and environmental factors, and while the effects of ultraviolet B radiation on melanoma development are well researched, fewer studies have investigated the role of ultraviolet A (UVA) radiation. We comprehensively reviewed cell, animal and epidemiology studies on the association between UVA exposure and melanomagenesis. UVA radiation has been found to have negative effects on melanocytes due to the induction of oxidative stress, dysregulation of gene transcription and creation of mutagenic photoproducts in DNA. Animal studies demonstrate adverse effects of UVA on melanocytes, including the development of melanoma. Epidemiology studies, of varying quality, that examined participants' exposure to tanning devices which use UVA radiation primarily found that UVA exposure increased the risk for melanoma. Some studies reported larger associations with increased frequency of device use, suggestive of a dose-response relationship. Overall, we found that many studies supported a positive association between UVA exposure and melanoma on both molecular and population levels. Understanding the role of UVA in the development of melanoma will inform the implementation of preventive health interventions, such as those related to sunscreen development and use and increasing restrictions on indoor tanning.

MC1R and melanin-based molecular probes for theranostic of melanoma and beyond

Malignant melanoma is accounting for most of skin cancer-associated mortality. The incidence of melanoma increased every year worldwide especially in western countries. Treatment efficiency is highly related to the stage of melanoma. Therefore, accurate staging and restaging play a pivotal role in the management of melanoma patients. Though 18F-fluorodeoxyglucose (18F-FDG) positron-emission tomography (PET) has been widely used in imaging of tumor metastases, novel radioactive probes for specific targeted imaging of both primary and metastasized melanoma are still desired. Melanocortin receptor 1 (MC1R) and melanin are two promising biomarkers specifically for melanoma, and numerous research groups including us have been actively developing a plethora of radioactive probes based on targeting of MC1R or melanin for over two decades. In this review, some of the MC1R-targeted tracers and melanin-associated molecular imaging probes developed in our research and others have been briefly summarized, and it provides a quick glance of melanoma-targeted probe design and may contribute to further developing novel molecular probes for cancer theranostics.

Amount of Melanin Granules in Human Hair Defines the Absorption and Conversion to Heat of Light Energy in the Visible Spectrum

One of the known important functions of hair is protection from extensive sunlight. This protection is accomplished in large part due to natural hair pigmentation which is known to reflect the number of melanin granules (melanosomes) in the hair shaft, and melanin variants. Melanin takes in excessive light energy and converts it to heat in a process called absorption; heat is then dissipated into the environment as infrared radiation, thereby protecting the underlying skin. We used transmission electron microscopy (TEM) to visualize the melanosome counts in samples of human hair, and used thermal microscopy to measure the temperature changes of the samples when exposed to green and blue light lasers. In our experiments green light conversion to heat was highly correlated to the number of melanosomes, whereas blue light conversion to heat was less correlated, which may be because the reddish melanosomes it contains are less effective in absorbing energy from the blue spectrum of light. Anyway, we have shown the metals accumulation in the melanin can be easily visualized with TEM. We confirmed that the amount of melanin granules in human hair defines the conversion to heat of light energy in the visible spectrum.

UVA Radiation, DNA Damage, and Melanoma

Melanoma is a lethal type of skin tumor that has been linked with sunlight exposure chiefly in fair-skinned human populations. Wavelengths from the sun that can reach the earth's surface include UVA radiation (320-400 nm) and UVB radiation (280-320 nm). UVB effectively induces the formation of dimeric DNA photoproducts, preferentially the cyclobutane pyrimidine dimers (CPDs). The characteristic UVB signature mutations in the form of C to T mutations at dipyrimidine sequences are prevalent in melanoma tumor genomes and have been ascribed to deamination of cytosines within CPDs before DNA polymerase bypass. However, evidence from epidemiological, animal, and other experimental studies also suggest that UVA radiation may participate in melanoma formation. The DNA damage relevant for UVA includes specific types of CPDs at TT sequences and perhaps oxidative DNA damage to guanine, both induced by direct or indirect, photosensitization-mediated chemical and biophysical processes. We summarize the evidence for a potential role of UVA in melanoma and discuss some of the mechanistic pathways of how UVA may induce mutagenesis in melanocytes.

Topology and Excited State Multiplicity as Controlling Factors in the Carbazole-Photosensitized CPD Formation and Repair

Photosensitized thymine<>thymine (Thy<>Thy) formation and repair can be mediated by carbazole (Cbz). The former occurs from the Cbz triplet excited state via energy transfer, while the latter takes place from the singlet excited state via electron transfer. Here, fundamental insight is provided into the role of the topology and excited state multiplicity, as factors governing the balance between both processes. This has been achieved upon designing and synthesizing different isomers of trifunctional systems containing one Cbz and two Thy units covalently linked to the rigid skeleton of the natural deoxycholic acid. The results shown here prove that the Cbz photosensitized dimerization is not counterbalanced by repair when the latter, instead of operating through-space, has to proceed through-bond.

The Damaging Effects of Long UVA (UVA1) Rays: A Major Challenge to Preserve Skin Health and Integrity

Within solar ultraviolet (UV) light, the longest UVA1 wavelengths, with significant and relatively constant levels all year round and large penetration properties, produce effects in all cutaneous layers. Their effects, mediated by numerous endogenous chromophores, primarily involve the generation of reactive oxygen species (ROS). The resulting oxidative stress is the major mode of action of UVA1, responsible for lipid peroxidation, protein carbonylation, DNA lesions and subsequent intracellular signaling cascades. These molecular changes lead to mutations, apoptosis, dermis remodeling, inflammatory reactions and abnormal immune responses. The altered biological functions contribute to clinical consequences such as hyperpigmentation, inflammation, photoimmunosuppression, sun allergies, photoaging and photocancers. Such harmful impacts have also been reported after the use of UVA1 phototherapy or tanning beds. Furthermore, other external aggressors, such as pollutants and visible light (Vis), were shown to induce independent, cumulative and synergistic effects with UVA1 rays. In this review, we synthetize the biological and clinical effects of UVA1 and the complementary effects of UVA1 with pollutants or Vis. The identified deleterious biological impact of UVA1 contributing to clinical consequences, combined with the predominance of UVA1 rays in solar UV radiation, constitute a solid rational for the need for a broad photoprotection, including UVA1 up to 400 nm.

Melanoma Detection by AFM Indentation of Histological Specimens

Melanoma is visible unlike other types of cancer, but it is still challenging to diagnose correctly because of the difficulty in distinguishing between benign nevus and melanoma. We conducted a robust investigation of melanoma, identifying considerable differences in local elastic properties between nevus and melanoma tissues by using atomic force microscopy (AFM) indentation of histological specimens. Specifically, the histograms of the elastic modulus of melanoma displayed multimodal Gaussian distributions, exhibiting heterogeneous mechanical properties, in contrast with the unimodal distributions of elastic modulus in the benign nevus. We identified this notable signature was consistent regardless of blotch incidence by sex, age, anatomical site (e.g., thigh, calf, arm, eyelid, and cheek), or cancer stage (I, IV, and V). In addition, we found that the non-linearity of the force-distance curves for melanoma is increased compared to benign nevus. We believe that AFM indentation of histological specimens may technically complement conventional histopathological analysis for earlier and more precise melanoma detection.

Comparative Study of Δ9-Tetrahydrocannabinol and Cannabidiol on Melanogenesis in Human Epidermal Melanocytes from Different Pigmentation Phototypes: A Pilot Study

Δ9-tetrahydrocannabinol (THC) is one of the primary ingredients of cannabis plants and is responsible for the psychoactive properties of cannabis. While cannabidiol (CBD), the non-psychoactive compound from cannabis, has been shown to stimulate human epidermal melanogenesis, the effects of THC have not been addressed in human epidermal melanocytes. Moreover, to date, no study has tested the effects of these compounds on melanocytes differing in pigmentation, representative of different skin phototypes, which would be significant as different ethnicities are known to differentially metabolize these xenobiotics. Herein, the effects of THC were studied and compared alongside CBD in human epidermal melanocytes derived from lightly-pigmented (HEMn-LP; Caucasian) and darkly-pigmented (HEMn-DP; African-American) cells over a chronic exposure of 6 d. Results demonstrated that both compounds displayed cytotoxicity at 4 µM but stimulated melanin synthesis and tyrosinase activity in a similar manner in LP and DP cells at nontoxic concentrations of 1-2 µM. However, THC and CBD showed a differential effect on dendricity in both cells; THC and CBD reversibly increased dendricity in LP cells while there was no significant change in DP cells. THC and CBD induced higher levels of reactive oxygen species (ROS) in LP cells while there was no change in the ROS levels in DP cells. In summary, although THC was relatively less cytotoxic as compared to CBD to both LP and DP cells, it exhibited a similar capacity as CBD to stimulate melanin synthesis and export in LP cells which was accompanied by a significant oxidative stress. DP cells were relatively resistant to the effects of both THC and CBD which might implicate the protective effects conferred by melanin in dark-skinned individuals.

The Dark Side of Melanin Secretion in Cutaneous Melanoma Aggressiveness

Skin cancers are among the most common cancers worldwide and are increasingly prevalent. Cutaneous melanoma (CM) is characterized by the malignant transformation of melanocytes in the epidermis. Although CM shows lower incidence than other skin cancers, it is the most aggressive and responsible for the vast majority of skin cancer-related deaths. Indeed, 75% of patients present with invasive or metastatic tumors, even after surgical excision. In CM, the photoprotective pigment melanin, which is produced by melanocytes, plays a central role in the pathology of the disease. Melanin absorbs ultraviolet radiation and scavenges reactive oxygen/nitrogen species (ROS/RNS) resulting from the radiation exposure. However, the scavenged ROS/RNS modify melanin and lead to the induction of signature DNA damage in CM cells, namely cyclobutane pyrimidine dimers, which are known to promote CM immortalization and carcinogenesis. Despite triggering the malignant transformation of melanocytes and promoting initial tumor growth, the presence of melanin inside CM cells is described to negatively regulate their invasiveness by increasing cell stiffness and reducing elasticity. Emerging evidence also indicates that melanin secreted from CM cells is required for the immunomodulation of tumor microenvironment. Indeed, melanin transforms dermal fibroblasts in cancer-associated fibroblasts, suppresses the immune system and promotes tumor angiogenesis, thus sustaining CM progression and metastasis. Here, we review the current knowledge on the role of melanin secretion in CM aggressiveness and the molecular machinery involved, as well as the impact in tumor microenvironment and immune responses. A better understanding of this role and the molecular players involved could enable the modulation of melanin secretion to become a therapeutic strategy to impair CM invasion and metastasis and, hence, reduce the burden of CM-associated deaths.

The Double-Edged Sword of Oxidative Stress in Skin Damage and Melanoma: From Physiopathology to Therapeutical Approaches

The skin is constantly exposed to exogenous and endogenous sources of reactive oxygen species (ROS). An adequate balance between ROS levels and antioxidant defenses is necessary for the optimal cell and tissue functions, especially for the skin, since it must face additional ROS sources that do not affect other tissues, including UV radiation. Melanocytes are more exposed to oxidative stress than other cells, also due to the melanin production process, which itself contributes to generating ROS. There is an increasing amount of evidence that oxidative stress may play a role in many skin diseases, including melanoma, being the primary cause or being a cofactor that aggravates the primary condition. Indeed, oxidative stress is emerging as another major force involved in all the phases of melanoma development, not only in the arising of the malignancy but also in the progression toward the metastatic phenotype. Furthermore, oxidative stress seems to play a role also in chemoresistance and thus has become a target for therapy. In this review, we discuss the existing knowledge on oxidative stress in the skin, examining sources and defenses, giving particular consideration to melanocytes. Therefore, we focus on the significance of oxidative stress in melanoma, thus analyzing the possibility to exploit the induction of oxidative stress as a therapeutic strategy to improve the effectiveness of therapeutic management of melanoma.

Low-Cost Naked-Eye UVB and UVC Dosimetry Based on 3,3',5,5'-Tetramethylbenzidine

Ultraviolet radiation (UVR) is both useful to human beings and can cause irreversible harm of varying degrees (UVA, UVB, and UVC). Especially, in areas with excessive sunlight, the appearance of UVB results in an increased risk of skin cancer. On the other hand, UV lamps (254 nm, UVC) are widely used in disinfection (air, water, and factory food) and hospital sterilization; the leakage of UVC is thus sometimes inevitable, which may cause fatal injuries to the related staff. Therefore, low-cost UV dosimetry-based personal protective equipment (PPE) and industrial monitoring devices are of great importance. Here, for the first time, we found that 3,3',5,5'-tetramethylbenzidine (TMB) could be rapidly oxidized upon UVB and UVC irradiation in a dose-dependent manner, in which TMB acts as a self-photosensitizer. Since TMB is a typical and widely used chromogenic substrate in enzyme-linked immunosorbent assay (ELISA), it is well-commercialized with low cost and vast availability worldwide, which permitted the development of low-cost naked-eye UVB and UVC dosimetry. A wearable bracelet mounted with TMB-loaded paper was developed for successful indication of whether the UVB exposure in the sunlight exceeded the minimum erythema dose (MED). In addition, we also developed a clock dial equipped with a TMB solution for unattended detection of UVC leakage from UVC disinfection lamps. The UVB- and UVC-selective coloration and low cost of TMB offered remarkable potential in facile detection of UVR in our daily life.

Visible-Blind ZnMgO Colloidal Quantum Dot Downconverters Expand Silicon CMOS Sensors Spectral Coverage into Ultraviolet and Enable UV-Band Discrimination

Selective spectral detection of ultraviolet (UV) radiation is highly important across numerous fields from health and safety to industrial and environmental monitoring applications. Herein, a nontoxic, visible-blind, quantum dot (QD)-based sensing scheme that expands the spectral coverage of silicon complementary metal-oxide-semiconductor (CMOS) sensors into the UV, enabling efficient UV detection without affecting the sensor performance in the visible and UV-band discrimination, is reported. This scheme uses zinc magnesium oxide (ZnMgO) QDs with compositionally tunable absorption across UV and high photoluminescence quantum yield in the visible. The efficient luminescence and large Stokes shift of these QDs are exploited herein to act as an efficient downconverting material that enhances the UV sensitivity of Si-photodetectors (Si-PDs). A Si-PD integrated with the QDs results in a ninefold improvement in photoresponsivity from 0.83 to 7.5 mA W^-1 at 260 nm. Leveraging the tunability of these QDs, a simple UV-band identification scheme is further reported, which uses two distinct-bandgap ZnMgO QDs stacked in a tandem architecture whose spectral emission color depends on the UV-band excitation light. The downconverting stack enables facile discrimination of UV light using a standard CMOS image sensor (camera) or by the naked eye and avoids the use of complex optics.

Investigation of the HelioVital filter foil revealed protective effects against UVA1 irradiation-induced DNA damage and against UVA1-induced expression of matrixmetalloproteinases (MMP) MMP1, MMP2, MMP3 and MMP15

The damaging effects of solar ultraviolet (UV) radiation exposure to human skin are well known and can reach from accelerated skin aging (photoaging) to skin cancer. Much of the damaging effects of solar UVA (320-400 nm) radiation is associated with the induction of reactive oxygen species (ROS), which are capable to cause oxidative damage to DNA like the oxidized guanosine 8-hydroxy-2' -deoxyguanosine (8-OHdG). Therefore, new UV protective strategies, have to be tested for their efficiency to shield against UV induced damage. We investigated the protective effects of HelioVital sun protection filter foil against UVA1 irradiation in skin cells. It could be shown, that HelioVital sun protection filter foil has protective effects against UVA1 irradiation induced changes in matrix metalloproteinase (MMP) expression. Furthermore a UVA1-dependant regulation of MMP15 in human fibroblasts could be shown for the first time in this context. In addition, this study demonstrated the protective effect of the HelioVital filter film against UVA1-induced ROS production and DNA damage. These results could pave the way for clinical studies with HelioVital filter foil shielding against the damaging effects of phototherapy and other forms of irradiation therapy, thereby increasing the safety and treatment opportunities of these forms of therapy.

Photoprotection by clothing: A review

Clothing is recognized by leading health agencies as a primary method to protect against the harmful effects of photodamage caused by ultraviolet (UV) radiation and visible light. The photoprotective capacity of clothing is commonly measured as the ultraviolet protective factor (UPF). While the technology driving photoprotective clothing has been well-established, there continues to be efforts to discover new materials to improve the UPF of clothing. Here, we show increased Google searches for photoprotective clothing over the last decade, suggesting a high level of public interest in photoprotective clothing. In addition, we investigate the frequency of UPF-graded photoprotective clothing sold by large retail stores featured in Fortune 1000. We review factors that alter the UPF of clothing and describe emerging textile technologies used to increase clothing's photoprotective capacity. Finally, we compare how photoprotective clothing is regulated among different countries, the importance of photoprotective clothing in occupational health, and research in visible light and clothing photoprotection.

Model Studies on the Photoreduction of the 5-Hydroxy-5,6-dihydrothymine and 5-Methyl-2-pyrimidone Moieties of (6-4) Photoproducts by Photolyase

Photorepair mechanism of (6‐4) photoproducts (6‐4PP) by photolyase has been the subject of active debate over the years. The initial rationalization based on electron transfer to an oxetane or azetidine intermediate formed upon binding to the enzyme has been questioned, and there is now a more general consensus that the lesion is directly reduced from the excited flavin cofactor. However, the accepting moiety, i.e. the 5‐methyl‐2‐pyrimidone or 5‐hydroxy‐5,6‐dihydrothymine, has not been fully identified yet. In this work, spectroscopic experiments have been run to determine which of the 5′‐ or 3′‐base of 6‐4PP is more prone to be reduced. For this aim, the two building blocks of 6‐4PP were synthesized and used as electron acceptors. Instead of the short‐lived photolyase cofactor, which does not provide a time window compatible with diffusion‐controlled intermolecular processes, carbazole, 2‐methoxynaphthalene and phenanthrene have been selected as electron donors due to their appropriate singlet lifetimes and reduction potentials. Steady‐state and time‐resolved fluorescence revealed that, in solution, the pyrimidone chromophore is the most easily reduced moiety. This was confirmed by transient absorption experiments consisting of quenching of the solvated electron by the two moieties of 6‐4PP.

Melanoma, Melanin, and Melanogenesis: The Yin and Yang Relationship

Melanin pigment plays a critical role in the protection against the harmful effects of ultraviolet radiation and other environmental stressors. It is produced by the enzymatic transformation of L-tyrosine to dopaquinone and subsequent chemical and biochemical reactions resulting in the formation of various 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and 5,6-dihydroxyindole (DHI) oligomers-main constituents of eumelanin, and benzothiazine and benzothiazole units of pheomelanin. The biosynthesis of melanin is regulated by sun exposure and by many hormonal factors at the tissue, cellular, and subcellular levels. While the presence of melanin protects against the development of skin cancers including cutaneous melanoma, its presence may be necessary for the malignant transformation of melanocytes. This shows a complex role of melanogenesis in melanoma development defined by chemical properties of melanin and the nature of generating pathways such as eu- and pheomelanogenesis. While eumelanin is believed to provide radioprotection and photoprotection by acting as an efficient antioxidant and sunscreen, pheomelanin, being less photostable, can generate mutagenic environment after exposure to the short-wavelength UVR. Melanogenesis by itself and its highly reactive intermediates show cytotoxic, genotoxic, and mutagenic activities, and it can stimulate glycolysis and hypoxia-inducible factor 1-alpha (HIF-1α) activation, which, combined with their immunosuppressive effects, can lead to melanoma progression and resistance to immunotherapy. On the other hand, melanogenesis-related proteins can be a target for immunotherapy. Interestingly, clinicopathological analyses on advanced melanomas have shown a negative correlation between tumor pigmentation and diseases outcome as defined by overall survival and disease-free time. This indicates a "Yin and Yang" role for melanin and active melanogenesis in melanoma development, progression, and therapy. Furthermore, based on the clinical, experimental data and diverse effects of melanogenesis, we propose that inhibition of melanogenesis in advanced melanotic melanoma represents a realistic adjuvant strategy to enhance immuno-, radio-, and chemotherapy.

Bystander effect of ultraviolet A radiation protects A375 melanoma cells by induction of antioxidant defense

Ultraviolet (UV) irradiated cells release factors that result in varied responses by non-irradiated cells via bystander effects (BE). The UV-BE is dependent on the cell types involved and on the wavelength of the radiation. Using conditioned medium from UVA-irradiated A375 human melanoma cells (UVA-CM), UVA-bystander response was evaluated on the viability of naïve A375 cells. UVA-CM treatment itself did not alter cell viability; however, UVA-CM treated bystander cells were more resistant to the lethal action of UVA, UVB, UVC or H₂O₂. Effects of UVA-CM on cell proliferation, mechanism of cell death, DNA damage, malondialdehyde formation, generation of reactive oxygen species (ROS) and antioxidant status were studied in A375 cells. We observed that UVA-CM triggered antioxidant defenses to elicit protective responses through elevation of antioxidant enzyme activities in cells, which persisted until 5 h after exposure to UVA-CM. This was possibly responsible for decreased generation of ROS and diminished DNA and membrane damage in cells. These bystander cells were resistant to killing when exposed to different genotoxic agents. Damaged nuclei, induction of apoptosis and autophagic death were also lowered in these cells. The influence of UVA-CM on cancer stem cells side population was assessed.Highlights:UVA radiation induced bystander effects in A375 cellsDamage by genotoxicants is suppressed due to lower ROS generation on UVA-CM treatmentUVA-CM exposure enhanced higher activities of CAT and GPxResistance to genotoxic agents in such cells was due to elevated antioxidant defenceUVA-bystander phenomenon was a protective response.

Modelling Photoionisation in Isocytosine: Potential Formation of Longer-Lived Excited State Cations in its Keto Form

Studying the effects of UV and VUV radiation on non-canonical DNA/RNA nucleobases allows us to compare how they release excess energy following absorption with respect to their canonical counterparts. This has attracted much research attention in recent years because of its likely influence on the origin of our genetic lexicon in prebiotic times. Here we present a CASSCF and XMS-CASPT2 theoretical study of the photoionisation of non-canonical pyrimidine nucleobase isocytosine in both its keto and enol tautomeric forms. We analyse their lowest energy cationic excited states including 2 π + , 2 n O + and 2 n N + and compare these to the corresponding electronic states in cytosine. Investigating lower-energy decay pathways we find - unexpectedly - that keto-isocytosine+ presents a sizeable energy barrier potentially inhibiting decay to its cationic ground state, whereas enol-isocytosine+ features a barrierless and consequently ultrafast pathway analogous to the one previously found for the canonical (keto) form of cytosine+ . Dynamic electron correlation reduces the energy barrier in the keto form substantially (by ∼1 eV) but it is nevertheless still present. We additionally compute the UV/Vis absorption signals of the structures encountered along these decay channels to provide spectroscopic fingerprints to assist future experiments in monitoring these intricate photo-processes.

Perspectives on Cyclobutane Pyrimidine Dimers-Rise of the Dark Dimers†

Some early reports demonstrate that levels of cyclobutane pyrimidine dimers (CPD) may increase after UVR exposure had ended, although these observations were treated as artifacts. More recently, it has been shown unequivocally that CPD formation does occur post-irradiation, with maximal levels occurring after about 2-3 h. These lesions have been termed "dark CPD" (dCPD). Subsequent studies have confirmed their presence in vitro, in mouse models and in human skin in vivo. Melanin carbonyls have a role in the formation of dCPD, but they have also been observed in amelanotic systems, indicating other, unknown process(es) exist. In both cases, the formation of dCPD can be prevented by the presence of certain antioxidants. We lack data on the spectral dependence of dCPD, but it is unlikely to be the same as for incident CPD (iCPD), which are formed only during irradiation. There is evidence that iCPD and dCPD may have different repair kinetics, although this remains to be elucidated. It is also unknown whether iCPD and dCPD have different biological properties. The formation of dCPD in human skin in vivo has implications for post solar exposure photoprotection, and skin carcinogenesis, with a need for this to be investigated further.