New agents for prevention of ultraviolet-induced nonmelanoma skin cancer

Algorithmic approach toward diagnosis of patients with congenital photosensitivity disorders and review of literature

The congenital photosensitivity disorders present as cutaneous signs and symptoms secondary to photosensitivity, extracutaneous manifestations, and a predisposition to malignancy. Diagnosis of these conditions mainly depend on clinical findings as the molecular analysis is not always feasible. A review of all the related articles collected after a thorough literature search using keywords, "congenital AND photosensitivity NOT acquired" and the individual diseases was done. A total of 264 articles were included in the review. An algorithm for diagnosis of the different congenital photosensitivity disorders based on the various clinical presentations has been proposed. An early suspicion and diagnosis of the different congenital photosensitivity disorders is the cornerstone behind prompt institution of prevention and treatment, and decreasing the associated morbidity.

Unravelling the photoprotective effects of freshwater alga Nostoc commune Vaucher ex Bornet et Flahault against ultraviolet radiations

Several studies have suggested the direct relationship between skin complications, air pollution, and UV irradiation. UVB radiations cause various skin complications such as skin aging, skin inflammation, and skin cancer. The current study is designed to develop an ultraviolet (UV) absorbing MAA-loaded topical gel and to evaluate its UVA and UVB screening potential. MAA was extracted from the Nostoc commune Vaucher ex Bornet et Flahault (N. commune) and characterized by HPLC-PDA (with a retention time 2.6 min), UV-Visible (absorption maximum 334 nm), and mass spectrometry (m/z 346.2) techniques. The methanolic (10%) solution of MAA (50-150 μl) was dissolved in propylene glycol and mixed with hydrated gel (1.5 % of carbopol 934) by using EDTA (0.3%). Eight (F1-F8) formulations were evaluated for their physico-chemical characters. F7 retained its physio-chemical characters for 90 days. Further selected formulation (F7) was evaluated for its gelling strength (GSg), gelling temperature (GT), melting temperature (MT), apparent viscosity (cp), molecular mass (MMS), pH, physical appearance, homogeneity, and spreading diameter (SD). The stability study of the fabricated gel formulation was done as per International Committee on Harmonization guidelines and sunscreen potential was determined by in vitro sunscreen UV method. Findings revealed that GSg (337 ± 1.7 g/cm²), GT (22.8 ± 0.2 °C), cp (71.1 ± 0.2), MMS (424.177 ± 0.7), pH (6.2 ± 0.04), and SD (56 ± 0.2). For in vitro sunscreen potential determination, different concentrations of F7 (50-150 μl) were prepared. Topical application of the F7 displayed UV-A/UV-B photoprotection with SPF 1.13 folds greater then marketed formulation (Lotus herbals UV screen gel). Based on these findings, it was concluded that methanolic extract derived from N. commune contains Porphyra-334 which can be potentially used as photo protective compound in several cosmetic preparations. Development of sunscreen gel from Nostoc commune The current investigation is designed to develop ultraviolet (UV) absorbing MAA (mycosporine amino acid)-loaded topical gel from Nostoc commune to evaluate its UVA and UVB screening potential. LCMS characterization of HPLC-PDA purified MAA from N. commune methanolic extract demonstrated a prominent ion peak of a protonated molecule ([M + H]⁺) at m/z 346.2 [M+H]+ value confirmed the presence of Porphyra-334. Porphyra-334 is a broad-spectrum sun-protective compound evidenced for its potential in blocking UVA and UVB (Bhatia et al. 2010). Prepared sunscreen formulations remain stable for prolonged period and provide broad-spectrum protection against harmful UV range.

Xeroderma Pigmentosum: General Aspects and Management

Xeroderma Pigmentosum (XP) is a rare genetic syndrome with a defective DNA nucleotide excision repair. It is characterized by (i) an extreme sensitivity to ultraviolet (UV)-induced damages in the skin and eyes; (ii) high risk to develop multiple skin tumours; and (iii) neurologic alterations in the most severe form. To date, the management of XP patients consists of (i) early diagnosis; (ii) a long-life protection from ultraviolet radiation, including avoidance of unnecessary UV exposure, wearing UV blocking clothing, and use of topical sunscreens; and (iii) surgical resections of skin cancers. No curative treatment is available at present. Thus, in the last decade, in order to prevent or delay the progression of the clinical signs of XP, numerous strategies have been proposed and tested, in some cases, with adverse effects. The present review provides an overview of the molecular mechanisms featuring the development of XP and highlights both advantages and disadvantages of the clinical approaches developed throughout the years. The intention of the authors is to sensitize scientists to the crucial aspects of the pathology that could be differently targeted. In this context, the exploration of the process underlining the conception of liposomal nanocarriers is reported to focus the attention on the potentialities of liposomal technology to optimize the administration of chemoprotective agents in XP patients.

Prevention of Skin Carcinogenesis by the Non-β-blocking R-carvedilol Enantiomer

Skin cancer is the most common malignancy worldwide and is rapidly rising in incidence, representing a significant public health challenge. The β-blocker, carvedilol, has shown promising effects in preventing skin cancer. However, as a potent β-blocker, repurposing carvedilol to an anticancer agent is limited by cardiovascular effects. Carvedilol is a racemic mixture consisting of equimolar S- and R-carvedilol, whereas the R-carvedilol enantiomer does not possess β-blocking activity. Because previous studies suggest that carvedilol's cancer preventive activity is independent of β-blockade, we examined the skin cancer preventive activity of R-carvedilol compared with S-carvedilol and the racemic carvedilol. R- and S-carvedilol were equally effective in preventing EGF-induced neoplastic transformation of the mouse epidermal JB6 Cl 41-5a (JB6 P+) cells and displayed similar attenuation of EGF-induced ELK-1 activity. R-carvedilol appeared slightly better than S-carvedilol against UV-induced intracellular oxidative stress and release of prostaglandin E₂ from the JB6 P+ cells. In an acute UV-induced skin damage and inflammation mouse model using a single irradiation of 300 mJ/cm² UV, topical treatment with R-carvedilol dose dependently attenuated skin edema and reduced epidermal thickening, Ki-67 staining, COX-2 protein, and IL6 and IL1β mRNA levels similar to carvedilol. In a chronic UV (50-150 mJ/cm²) induced skin carcinogenesis model in mice with pretreatment of test agents, topical treatment with R-carvedilol, but not racemic carvedilol, significantly delayed and reduced skin squamous cell carcinoma development. Therefore, as an enantiomer present in an FDA-approved agent, R-carvedilol may be a better option for developing a safer and more effective preventive agent for skin carcinogenesis. PREVENTION RELEVANCE: In this study, we demonstrated the skin cancer preventive activity of R-carvedilol, the non-β-blocking enantiomer present in the racemic β-blocker, carvedilol. As R-carvedilol does not have β-blocking activity, such a preventive treatment would not lead to common cardiovascular side effects of β-blockers.

Murine Skin Carcinogenesis and the Role of Immune System Dysregulation in the Tumorigenicity of 2-Ethylhexyl Acrylate

Some chemicals act as human carcinogens in various organ systems including the skin. Mice have been an ideal model to study a wide variety of chemical carcinogens because the pathogenesis in that species often mirrors that in humans. However, different mouse strains vary in their susceptibility to these agents. Thus, reliance on a single strain may lead to inaccurate findings. 2-Ethylhexyl acrylate (2-EHA) is an acrylate used as a co-monomer in the production of polymer resins for adhesives, latex paints, cross-linking agents, finishes for textiles and leather, and paper coatings. Monomer exposure may occur in occupational settings where it is produced or used; the only exposure that may occur to consumers or construction personnel is trace amounts in the final polymer product. There are no reports of cancer in humans caused by exposure to 2-EHA. However, 2-EHA has been reported to cause cancer in one strain of mice. This is an important issue since recommendations about its safety in humans depend, in part, on information derived from animal studies. We reviewed the literature on the preclinical effects of acrylates on skin carcinogenesis in C3H/HeJ mice, which can be criticized because of peculiarities in the immunological composition of that strain, the lack of rigorous histopathologic characterization of tumors that developed, the high doses of 2-EHA that were used for evaluation, and the lack of reproducibility in a second strain of mice. The C3H/HeJ mouse model is not ideal as it has a mutation in Toll-like receptor 4 (TLR4) that impairs its innate and adaptive immune responses. Inconsistencies in the histological evaluation of tumors induced in C3H/HeJ mice provide further evidence that the tumorigenic effect of 2-EHA was strain specific, a result of chronic inflammation during the promotion stage and/or a skewed immune response caused by the TLR4 mutation. In conclusion, 2-EHA has not convincingly been demonstrated to have skin carcinogenic activity to date. More relevant mouse models that mimic human squamous cell carcinoma, basal cell carcinoma, and melanoma with amounts that do not exceed a maximum tolerated dose are needed to assess the carcinogenic effects of 2-EHA.

Dietary Fat Intake and the Risk of Skin Cancer: A Systematic Review and Meta-Analysis of Observational Studies

We conducted a meta-analysis to evaluate the association between fat intake and the risk of three major types of skin cancer including basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and cutaneous malignant melanoma (CMM). A comprehensive search of PubMed and EMBASE was performed to identify all relevant observational studies published up to December 1, 2018. Specific odds ratio (OR) or relative risk (RR) estimates for the highest versus the lowest intake of dietary fat and 95% confidence intervals (CI) from the included studies were pooled using random effect model. Three prospective cohort studies (175,675 participants and 30,915 BCC cases, 4,106 SCC cases and 1,638 CMM cases) and nine case-control studies (328 BCC cases, 493 SCC cases, 1,547 CMM cases and 2,660 controls) were identified. The pooled results indicated that dietary consumption of total fat and saturated fat were not associated with three major types of skin cancer. High consumption of monounsaturated fat was significantly associated with a decreased risk of BCC (RR: 0.90, 95% CI: 0.85-0.96) and high level of polyunsaturated fat intake was potentially positively associated with SCC (RR: 1.19, 95% CI: 1.06-1.33). Our findings should be confirmed by further evidence from well-designed and large-scale prospective cohort studies.

Diet and Skin Cancer: The Potential Role of Dietary Antioxidants in Nonmelanoma Skin Cancer Prevention

Nonmelanoma skin cancer (NMSC) is the most common cancer among Americans. Ultraviolet (UV) radiation exposure is the major risk factor for the development of NMSC. Dietary AOs may prevent free radical-mediated DNA damage and tumorigenesis secondary to UV radiation. Numerous laboratory studies have found that certain dietary AOs show significant promise in skin cancer prevention. These results have been substantiated by animal studies. In human studies, researchers have evaluated both oral AO supplements and dietary intake of AOs via whole foods. In this review, we provide an overview of the role of AOs in preventing tumorigenesis and outline four targeted dietary AOs. We review the results of research evaluating oral AOs supplements as compared to dietary AOs intake via whole foods. While these specific supplements have not shown efficacy, intake of AOs via consumption of whole foods has shown some promise. Lessons learned from the field of hypertension research may provide important guidance in future study design. Further research on the role of dietary AOs in the prevention of NMSC is warranted and should focus on intake via whole food consumption.

Design, synthesis and structure-activity relationship studies of novel and diverse cyclooxygenase-2 inhibitors as anti-inflammatory drugs

Because of the pivotal role of cyclooxygenase (COX) in the inflammatory processes, non-steroidal anti-inflammatory drugs (NSAIDs) that suppress COX activities have been used clinically for the treatment of inflammatory diseases/syndromes; however, traditional NSAIDs exhibit serious side-effects such as gastrointestinal damage and hyper sensitivity owing to their COX-1 inhibition. Also, COX-2 inhibition-derived suppressive or preventive effects against initiation/proliferation/invasion/motility/recurrence/metastasis of various cancers/tumours such as colon, gastric, skin, lung, liver, pancreas, breast, prostate, cervical and ovarian cancers are significant. In this study, design, synthesis and structure-activity relationship (SAR) of various novel {2-[(2-, 3- and/or 4-substituted)-benzoyl, (bicyclic heterocycloalkanophenyl)carbonyl or cycloalkanecarbonyl]-(5- or 6-substituted)-1H-indol-3-yl}acetic acid analogues were investigated to seek and identify various chemotypes of potent and selective COX-2 inhibitors for the treatment of inflammatory diseases, resulting in the discovery of orally potent agents in the peripheral-inflammation model rats. The SARs and physicochemical properties for the analogues are described as significant findings. For graphical abstract: see Supplementary Material. ( www.informahealthcare.com/enz ).

Consumption of omega-3 fatty acids and the risk of skin cancers: a systematic review and meta-analysis

Skin cancers have a higher incidence than all other cancers combined and are a major cause of morbidity worldwide. Laboratory data suggest certain dietary constituents, notably omega-3 polyunsaturated fatty acids (n-3 PUFAs), could potentially protect against skin malignancy, although no large-scale review has been conducted in humans. The objective of this review and meta-analysis was to determine the relationship between dietary n-3 PUFAs and skin cancer incidence. It considered all published randomized controlled trials and observational studies up to March 2013. Five studies (two case-control and three cohort) were identified pertaining to oral n-3 PUFA consumption and incidence of basal cell carcinoma (BCC), squamous cell carcinoma (SCC), melanoma (or a combination) and were included in a random-effects meta-analysis. A further six studies considering nondietary n-3 PUFA exposure (e.g., by tissue analysis) and/or recognized biological markers of skin cancer risk (e.g., p53 expression) were analyzed qualitatively. Dietary n-3 PUFAs were not associated with BCC (pooled OR 1.05, 95% CIs 0.86-1.28). Consumption of high levels of n-3 PUFAs were inversely associated with melanoma, although with only one estimate available (OR 0.52, 95% CI 0.34-0.78), and SCC, although nonsignificantly (pooled OR 0.86, 95% CIs 0.59-1.23). Available evidence is suggestive, but currently inadequate, to support the hypothesis that n-3 PUFAs protect against skin malignancy.

Nonmelanoma skin cancer of the head and neck: prevention

The importance and effectiveness of prevention efforts and strategies for skin cancers are reviewed. Topical sunscreens and their proper use are presented. Topical and ingested forms of natural, synthetic, or biologic chemical agents that are potentially efficacious for chemoprevention are listtdldted and discussed.