Melanoma and sun exposure: where are we now?

Transethosomal Gel for the Topical Delivery of Celecoxib: Formulation and Estimation of Skin Cancer Progression

The topical delivery of therapeutics is a promising strategy for managing skin conditions. Cyclooxygenase-2 (COX-2) inhibitors showed a possible target for chemoprevention and cancer management. Celecoxib (CXB) is a selective COX-2 inhibitor that impedes cell growth and generates apoptosis in different cell tumors. Herein, an investigation proceeded to explore the usefulness of nano lipid vesicles (transethosomes) (TES) of CXB to permit penetration of considerable quantities of the drug for curing skin cancer. The prepared nanovesicles were distinguished for drug encapsulation efficiency, vesicle size, PDI, surface charge, and morphology. In addition, FT-IR and DSC analyses were also conducted to examine the influence of vesicle components. The optimized formulation was dispersed in various hydrogel bases. Furthermore, in vitro CXB release and ex vivo permeability studies were evaluated. A cytotoxicity study proceeded using A431 and BJ1 cell lines. The expression alteration of the cyclin-dependent kinase inhibitor 2A (CDKN2A) gene and DNA damage and fragmentation using qRT-PCR and comet assays were also investigated. Optimized CXB-TES formulation was spherically shaped and displayed a vesicle size of 75.9 ± 11.4 nm, a surface charge of -44.7 ± 1.52 mV, and an entrapment efficiency of 88.8 ± 7.2%. The formulated TES-based hydrogel displayed a sustained in vitro CXB release pattern for 24 h with an enhanced flux and permeation across rat skin compared with the control (free drug-loaded hydrogel). Interestingly, CXB-TES hydrogel has a lower cytotoxic effect on normal skin cells compared with TES suspension and CXB powder. Moreover, the level of expression of the CDKN2A gene was significantly (p ≤ 0.01, ANOVA/Tukey) decreased in skin tumor cell lines compared with normal skin cell lines, indicating that TES are the suitable carrier for topical delivery of CXB to the cancer cells suppressing their progression. In addition, apoptosis demonstrated by comet and DNA fragmentation assays was evident in skin cancer cells exposed to CXB-loaded TES hydrogel formulation. In conclusion, our results illustrate that CXB-TES-loaded hydrogel could be considered a promising carrier and effective chemotherapeutic agent for the management of skin carcinoma.

CDKN2A/CDK4 Status in Greek Patients with Familial Melanoma and Association with Clinico-epidemiological Parameters

Approximately 5–10% of melanoma cases occur in a familial context. CDKN2A/CDK4 were the first high- penetrance melanoma genes identified. The aims of this study were to evaluate CDKN2A/CDK4 variants in Greek familial melanoma patients and to correlate the mutational status with specific clinico-epidemiological characteristics. A cross-sectional study was conducted by genotyping CDKN2A/CDK4 variants and selected MC1R polymorphisms in 52 melanoma-prone families. Descriptive statistics were calculated and comparisons were made using the X² test, Fisher’s exact test and Student’s t-test for statistical analysis, as appropriate. CDKN2A variants were detected in 46.2% of melanoma-prone families, while a CDK4 variant was found in only one family. This study confirmed that, in the Greek population, the age at melanoma diagnosis was lower in patients carrying a variant in CDKN2A compared with wild-type patients. No statistically significant associations were found between CDKN2A mutational status and MC1R polymorphisms.

Climatic Conditions and the Reporting of Sun-Protective Behavior Survey Data: A Brief Report

Two hundred thirty-one spectators at a Cricket match in Brisbane, Australia, were interviewed and observed to determine their sun protective behaviors, and these behaviors were compared to the temperature and amount of cloud cover at the time of the study. People tended to protect themselves from the sun when there was less cloud cover and temperatures were higher.

Characterization of individuals at high risk of developing melanoma in Latin America: bases for genetic counseling in melanoma

Purpose:

CDKN2A is the main high-risk melanoma-susceptibility gene, but it has been poorly assessed in Latin America. We sought to analyze CDKN2A and MC1R in patients from Latin America with familial and sporadic multiple primary melanoma (SMP) and compare the data with those for patients from Spain to establish bases for melanoma genetic counseling in Latin America.

Genet Med18 7, 727–736.

Methods:

CDKN2A and MC1R were sequenced in 186 Latin American patients from Argentina, Brazil, Chile, Mexico, and Uruguay, and in 904 Spanish patients. Clinical and phenotypic data were obtained.

Genet Med18 7, 727–736.

Results:

Overall, 24 and 14% of melanoma-prone families in Latin America and Spain, respectively, had mutations in CDKN2A. Latin American families had CDKN2A mutations more frequently (P = 0.014) than Spanish ones. Of patients with SMP, 10% of those from Latin America and 8.5% of those from Spain had mutations in CDKN2A (P = 0.623). The most recurrent CDKN2A mutations were c.-34G>T and p.G101W. Latin American patients had fairer hair (P = 0.016) and skin (P < 0.001) and a higher prevalence of MC1R variants (P = 0.003) compared with Spanish patients.

Genet Med18 7, 727–736.

Conclusion:

The inclusion criteria for genetic counseling of melanoma in Latin America may be the same criteria used in Spain, as suggested in areas with low to medium incidence, SMP with at least two melanomas, or families with at least two cases among first- or second-degree relatives.

Genet Med18 7, 727–736.

Skin cancer and vitamin D: an update

Exposure of the skin to solar ultraviolet (UV) radiation has both risks and benefits for human health. Absorption of UV-B radiation by DNA results in mutations that underlie the development of skin cancers, as is apparent from genetic studies showing high occurrence of UV signature mutations within these tumors. UV-B radiation is also absorbed by 7-dehydrocholesterol to initiate vitamin D synthesis. In experimental studies vitamin D metabolites enhance apoptosis of malignant cells, inhibit angiogenesis and proliferation and increase differentiation, potentially reducing skin cancer development and improving prognosis after diagnosis. There are some supporting human data. We review the links between sun exposure, vitamin D and skin cancers.

Increased prevalence of lung, breast, and pancreatic cancers in addition to melanoma risk in families bearing the cyclin-dependent kinase inhibitor 2A mutation: implications for genetic counseling

BACKGROUND

Cyclin-dependent kinase inhibitor 2A (CDKN2A) is the major high-risk susceptibility gene for melanoma.

OBJECTIVE

We sought to evaluate the effect of CDKN2A mutations in Spanish patients with a high risk of developing melanoma and the association with clinical and family history features.

METHODS

A cross-sectional study design was used to analyze the CDKN2A impact in 702 Spanish patients with a high risk of developing melanoma.

RESULTS

The CDKN2A mutation prevalence was 8.5% in patients with sporadic multiple primary melanoma and 14.1% in familial melanoma. Number of cases in the family, number of primary melanomas, and age of onset were associated with the presence of CDKN2A mutation. Having a CDKN2A mutation in the family increased the prevalence of other cancers (prevalence ratio [PR] 2.99, P=.012) and prevalence of pancreatic (PR 2.97, P=.006), lung (PR 3.04, P<.001), and breast (PR 2.19, P=.018) cancers but not nephrourologic or colon cancer.

LIMITATIONS

Smoking status was not assessed in the individuals with lung cancer.

CONCLUSIONS

Melanoma-prone families with mutations in CDKN2A have an increased prevalence of a broad spectrum of cancers including lung, pancreatic, and breast cancer. This information should be included in genetic counseling and cancer prevention programs for CDKN2A mutation carriers.

North-South gradients of melanomas and non-melanomas: A role of vitamin D?

Incidence rates of skin cancer increase with decreasing latitude in Norway, as in many other countries with white populations. The latitudinal trends of the incidence rates of skin cancer were studied and compared with data for vitamin D-induced by UV and for vitamin D intake. The north-south gradient for CMM incidence rates on sun exposed skin is much smaller than those for BCC and SCC, and that for BCC is smaller than that for SCC. This indicates that SCC and BCC are mainly due to solar UVB, while UVA may play a significant role for CMM and a smaller role for BCC, since the north-south gradient of annual UVB fluences is larger than that of UVA fluences. However, there is an inverse latitudinal gradient of skin cancer in central Europe. This is probably due to a gradient of skin color, since white skin is an important determinant of increased risk of skin cancer. The role of vitamin D for skin cancer risk is difficult to evaluate, since serum levels of 25-hydroxyvitamin D, as well as vitamin D intakes, are widely different from country to country. Still, epidemiological evidence indicates a role: for melanomas arising on non-sun exposed body localizations (uveal melanomas, melanomas arising in the vulva and perianal/anorectal regions) there appears to be no latitudinal gradient, or, a negative gradient, i.e., increasing rates with decreasing latitude as would be expected if UV-generated vitamin D plays a protective role. Both skin cancer risk and vitamin D photosynthesis decrease with increasing skin darkness.

Antiproliferative activity of the isofuranonaphthoquinone isolated from Bulbine frutescens against Jurkat T cells

Cancer is a major public health burden in both developed and developing countries. The quinone moiety has been shown to possess antitumor activity and several cancer drugs in clinical use contain this entity. The effect of isofuranonaphthoquinone isolated from Bulbine frutescens on Jurkat T cells was determined. Cells were exposed to the isofuranonaphthoquinone (IFNQ) at different concentrations. Significant antiproliferative effects were observed which were comparable to that of the anticancer drug 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). A combination of IFNQ with BCNU produced synergistic effects which were observed after 72 hrs. It was also observed that combining IFNQ with reduced glutathione abolished the anticancer activity of the compound. It is, therefore, proposed that the isofuranonaphthoquinone may exert part of its effect by producing reactive oxygen species resulting in death of the cells as the effects of this compound were antagonized by reduced glutathione. An investigation on the effects of isofuranonaphthoquinone on glutathione transferase (GST) activity and drug efflux pumps showed that this compound exhibited inhibitory effects on both the GST and the drug efflux pumping activities. Thus, the isofuranonaphthoquinone showed cytotoxicity, works through inhibition of some cellular mechanisms, and could present a potential source of lead compounds for anticancer drug development.

Stressed out mitochondria: the role of mitochondria in ageing and cancer focussing on strategies and opportunities in human skin

Mitochondrial DNA damage has been used as a successful and unique biomarker of tissue stress. A valuable example of this is sun damage in human skin which leads to ageing and skin cancer. The skin is constantly exposed to the harmful effects of sunlight, such as ultraviolet radiation, which causes it to age with observable characteristic features as well as clinical precancerous lesions and skin cancer. Formation of free radicals by the sun's harmful rays which contribute to oxidative stress has been linked to the induction of deletions and mutations in the mitochondrial DNA. These markers of mitochondrial DNA damage have been proposed to contribute to the mechanisms of ageing in many tissues including skin and are associated with many diseases including cancer. In this article we highlight the role of this important organelle in ageing and cancer with particular emphasis on experimental strategies in the skin.

From melanocyte to metastatic malignant melanoma

Malignant melanoma is one of the most aggressive malignancies in human and is responsible for almost 60% of lethal skin tumors. Its incidence has been increasing in white population in the past two decades. There is a complex interaction of environmental (exogenous) and endogenous, including genetic, risk factors in developing malignant melanoma. 8–12% of familial melanomas occur in a familial setting related to mutation of the CDKN2A gene that encodes p16. The aim of this is to briefly review the microanatomy and physiology of the melanocytes, epidemiology, risk factors, clinical presentation, historical classification and histopathology and, more in details, the most recent discoveries in biology and genetics of malignant melanoma. At the end, the final version of 2009 AJCC malignant melanoma staging and classification is presented.

Rising trends in incidence of cutaneous malignant melanoma and their future projections in Catalonia, Spain: increasing impact or future epidemic?

BACKGROUND

During the past decades, there has been a substantial increase in the incidence of cutaneous malignant melanoma (CMM) among all Caucasian populations. Spain presents one of Europe's lowest incidence and mortality rates.

OBJECTIVE

The aim of this study was to analyse the recent trends of CMM incidence and mortality in a region with lower incidence as well as to project their future trends.

METHODS

Cutaneous malignant melanoma incidence data were provided by the Tarragona and Girona population-based cancer registries and mortality data were provided by the Mortality Registry of Catalonia. Time trends of incidence and mortality rates by CMM were assessed through the estimated annual percentages of change of the incidence and mortality age-standardized rates to the World Standard Population. Projections were based on a Bayesian age-period-cohort model using second order autoregressive effects on age.

RESULTS

During the last 20 years CMM incidence has increased substantially at a faster rate than any other neoplasms in Catalonia, particularly among women and this trend will probably continue for the next several years. Nevertheless, CMM mortality trends have been and probably will remain stable during this period.

CONCLUSION

Improvements in preventive activities should be implemented to decrease incidence and mortality from this cancer. Monitoring stage-specific trends in CMM incidence can assess the impact of preventive strategies; for this reason more complete information on diagnostic features of CMM patients in the Spanish population-based cancer registries are necessary.

Economic evaluation of skin cancer prevention in Australia

OBJECTIVES

Australia has the highest incidence of skin cancer in the world, despite prevention campaigns being implemented since the early 1980s. This study assesses the cost-effectiveness of a skin cancer prevention program (named SunSmart) since it was introduced, together with its potential cost-effectiveness as an upgraded and ongoing national program.

METHODS

The reduction in melanoma incidence attributable to SunSmart was modelled as the primary end-point. Historical expenditures on SunSmart were obtained from representative Australian states in three latitude zones. Melanoma incidence rates from these states were used to model key health outcomes. Non-melanoma skin cancer was modelled separately based on national survey results.

RESULTS

We estimate that SunSmart has averted 28,000 disability-adjusted life-years (DALYs), equivalent to 22,000 life-years saved, in the state of Victoria since its introduction in 1988, as well as saving money from cost offset in skin cancer management (dominant). An upgraded national program for the next 20 years is estimated to avert 120,000 DALYs, with associated reductions in the use of health care resources. It remains a dominant intervention in which every dollar invested in SunSmart will return an estimated AU$2.30.

CONCLUSIONS

This study demonstrates that a sustained modest investment in skin cancer control is likely to be an excellent value for money.

Ambient UVB and melanoma risk in the United States: a case-control analysis

PURPOSE

Exposure to ultraviolet-B (UVB) radiation is a well-established risk factor for human cutaneous malignant melanoma. Intermittent and cumulative exposures from UVB have been estimated most often by interview questionnaire. This study assessed cumulative UVB using a ground-based measurement instrument to estimate the association between UVB and melanoma.

METHODS

Population-based, incident cases of melanoma (n = 380) and frequency-matched controls (n = 364) residing in Connecticut at diagnosis were interviewed between 1987 and 1989 about recreational and vacation activities, sun-protection practices, occupation, and other factors. Using a residential history, regression estimates of lifetime UVB were derived from ambient measures of UVB, adjusted for intermittent exposure.

RESULTS

Cases and controls received 29% of lifetime mean UVB in the first 15 years of life. Number of days per year in recreational activity during childhood and late adulthood were associated with increased melanoma risk. When estimating lifetime UVB adjusted for intermittent exposure, melanoma risk peaked at a 5.7-fold increased risk in the ninth decile.

CONCLUSION

Sporadic and chronic sun exposure play a role in melanoma etiology. Skin-protection practices should be encouraged across levels of sun intensity, not only in childhood but throughout adulthood.

Sun exposure, diet, and melanoma in Hawaii Caucasians

Much uncertainty remains about the type of sunlight exposure that most increases risk of cutaneous melanoma and the role of diet. The authors conducted a population-based case-control study (1986-1992) of Caucasians living on Oahu, Hawaii; included were 278 cases and age- and sex-matched controls. Plasma samples were measured for retinol, carotenoids, and alpha-tocopherol by high-pressure liquid chromatography. Selenium was measured in blood and toenails by neutron activation. Celtic and English ancestries, migration to Hawaii before age 20 years, fair complexion, inability to tan, and family history of skin cancer, as well as height, hours spent in the summer sun, blistering sunburns during adolescence, and moles, all increased melanoma risk. With regard to diet and biomarkers, only alcohol was associated with risk. The odds ratios for increasing tertiles of lifetime ethanol intake were 1.0, 1.2 (95% confidence interval (CI): 0.6, 2.2), and 2.3 (95% CI: 1.2, 4.4) (p for trend = 0.01) for men and 1.0, 1.1 (95% CI: 0.5, 2.4), and 1.7 (95% CI: 0.7, 3.8) (p for trend = 0.19) for women. Dietary lipids were unrelated to risk, but polyunsaturated fat intake appeared to modify the effects of alcohol and toenail selenium on melanoma risk. These data provide additional evidence for the association of constitutional susceptibility factors, intense sun exposure (particularly before age 20 years), and alcohol consumption with melanoma risk.

Is head and neck melanoma a distinct entity? A clinical registry-based comparative study in 5702 patients with melanoma

BACKGROUND

The head and neck region is more heavily exposed to ultraviolet (UV) radiation than any other body site. Therefore, cutaneous malignant melanoma (CMM) of the head and neck area is proposed to have notable differences from melanoma at other body sites regarding clinicopathological features and survival of patients.

OBJECTIVES

The present retrospective study based on clinical registry data aims to compare clinical features and prognostic factors of head and neck melanoma (HNM) vs. melanoma at other anatomical regions (MOR) in order to detect differences which may be associated to the mode of sun exposure.

METHODS

The clinical records and histopathological findings of 844 patients with clinical stage I and II invasive HNM were compared with the data of 4858 patients with MOR. Survival analysis was performed using the Kaplan-Meier estimate, and the multivariate Cox proportional hazard model was used to evaluate independent prognostic factors.

RESULTS

Melanoma density was clearly higher for HNM than for MOR: this was particularly true for the face, where it was elevated by a factor of 2.6. There was a higher male/female ratio in patients with HNM and they were significantly older than patients with MOR (P < 0.0001). Breslow tumour thickness did not differ between HNM and MOR. However, CMMs at the scalp were significantly thicker and to a higher degree ulcerated. Concerning clinicopathological CMM subtypes, there was an increased proportion of lentigo maligna melanoma among HNM and of nodular melanoma in the scalp and neck regions. Excision margins were narrower and the rate of complete primary excision was lower in HNM than in MOR. Overall, there was no significant statistical difference in cumulative 10-year survival rates according to Kaplan-Meier estimates among patients with HNM (84.6%) and MOR (87.8%). Tumour thickness turned out to be the variable with the highest prognostic impact followed by ulceration in both HNM and MOR.

CONCLUSIONS

In relation to the skin surface significantly more CMMs were found in the head and neck area than in other anatomical regions. This might indicate, but does not prove, that UV exposure promotes the development of CMM. Although HNM showed specific clinicopathological features, prognosis remained unaffected. Thus HNM seems not to be a distinct subtype of CMM.

Policy and Practice for Preventing Skin Cancer in Children

This paper identifies what is known and what is not known about the link between sun exposure and skin cancer and what can be done to reduce sun exposure in children. There is evidence for the use of sun protective clothing and of the effectiveness of sunscreens for some, but not all, forms of skin cancer. While there is some evidence to support interventions in schools, there is insufficient evidence to support other interventions aimed at children or their caregivers. There is no clear means of assessing the "trade-off" between the benefits and harms of sunlight exposure, and the impact of sun protection strategies on other health promotion messages aimed at children is unknown. Reliance on educational interventions in schools may benefit from a broader approach that includes more emphasis on protective clothing and structural changes in the school day. Sun protection messages should be linked with other health promotion messages targeting children.

Miniature personal electronic UVR dosimeter with erythema response and time-stamped readings in a wristwatch

Personal ultraviolet radiation (UVR) dosimetry is important because sunlight is the most important risk factor for skin cancer and a risk factor for some eye diseases and immunosuppression and related disorders. Integrating devices, such as polysulphone film dosimeters, are generally used. To measure the exact dose at specific times, we have developed a personal electronic UVR dosimeter that makes time-stamped measurements. It has a sensor with an erythema action spectrum response and a linear sensitivity (dose-response) with no offset. The sensor has cosine response, and the dosimeter can cope with environmental conditions such as rain, temperature and dirt. It can be programmed to measure with different time intervals and save the average of a specified number of measurements in the memory that can store 32 000 time-stamped measurements. It is small (36 x 28 x 13 mm), weighs 14 g and can work for 4 months without maintenance. It is worn on the wrist, is equipped with a watch showing the time and may thus be used in large-scale studies. The sensitivity can change by 10% due to temperature changes from -5 to 40 degrees C. The UVR dosimeter sensitivity is 0.09 standard erythema doses (SED)/h and the difference in total received dose during 7 days between a Solar Light 501 UV-Biometer (186 SED) and our UVR dosimeter was 3% and the median difference in daily total dose was 2.2%. The dosimeter provides unique possibilities. Examples of personal UVR measurements, data calculations and how they can be interpreted are given.

Role of Sun Exposure in Melanoma

BACKGROUND

Malignant melanoma is the third most common skin cancer in the United States. It is commonly thought that sun exposure is causative in these tumors. Recently, however, the significance of the role of sun exposure in melanoma has come into question. Some have suggested that other factors, such as genetics, play a larger role, and that sun protection may even be harmful.

OBJECTIVE AND METHODS

To investigate the role of sun exposure in melanoma etiology. An extensive review of basic science and clinical literature on this subject was conducted.

RESULTS

Although exceptions exist, sun exposure likely plays a large role in most melanomas. The pattern of this exposure, however, is not fully known, and controversy exists, especially in the use of sunscreens. Sun exposure may interact with genetic factors to cause melanomas, and sun protective measures appear to be prudent.

CONCLUSIONS

The cause of melanoma is probably variable and multifactorial. Sun exposure may play a primary or supporting role in most melanoma tumors.

Skin cancer and non-Hodgkin's lymphoma: examining the link

BACKGROUND

The incidence rates of melanoma and non-Hodgkin's lymphoma (NHL) have increased substantially worldwide over the past several decades. It has been hypothesized that ultraviolet light exposure through sunlight may be a common environmental risk factor shared by both skin cancer and NHL.

OBJECTIVE

The purpose of this study was to better understand the association between skin cancer and NHL and to evaluate its implication in clinical practice.

METHODS

We reviewed the current literature on the link between the two malignancies and on the role of ultraviolet light in the development of NHL. Publications were selected using a PUBMED search with the terms "non-Hodgkin's lymphoma" and "skin cancer." Epidemiologic studies in English and published after 1995 were the focus.

CONCLUSIONS

Large population-based studies support an increased risk of subsequent NHL among patients with skin cancers (both melanoma and nonmelanoma skin cancers) and a risk of skin cancer development in patients with NHL, although support for a direct relationship between ultraviolet light and the incidence of NHL is weak and inconsistent. Given their increased risk of developing skin cancers, patients with a history of NHL may benefit from a full-body examination during their visits.

Loss of p16 expression is associated with histological features of melanoma invasion

While mutations of CDKN2A are associated with melanoma predisposition, the precise role of its gene product p16 in the development of sporadic melanoma is less clearly understood. We sought to determine the prevalence of p16 expression using immunohistochemical analysis in a population-based sample of melanoma tumours, and also to identify histological, phenotypic and environmental factors associated with the presence or absence of p16 expression. We conducted face-to-face interviews with 108 patients newly diagnosed with melanoma to ascertain their history of sun exposure, and recorded various phenotypic parameters. Paraffin sections of tumours from these patients were stained with an anti-p16 monoclonal antibody following antigen retrieval. Overall, 52 (48%) tumours expressed p16; nodular melanomas had significantly lower levels of p16 immunoreactivity than superficial spreading melanomas (P = 0.015). While no association was found between p16 expression and host phenotype, loss of p16 staining was associated with thicker lesions (p = 0.084) and a high mitotic index (P = 0.013). Taken together, these findings are consistent with loss of p16 being a late event in the progression of sporadic primary melanomas, being associated with tumours of a more aggressive nature.

A natural history of melanomas and dysplastic nevi: an atlas of lesions in melanoma-prone families

BACKGROUND

Few long-term clinical and histologic data for melanocytic lesions have been available based on the mutation status of families at an increased risk of melanoma. In the current study, the authors describe the clinical and histologic features of dysplastic nevi and melanoma over time in families at an increased risk of melanoma with differing germline mutations in CDKN2A, CDK4, or not yet identified genes.

METHODS

Thirty-three families with > 2 living members with invasive melanoma were evaluated clinically and followed prospectively for up to 25 years. All the participants were evaluated by the same study team at the Clinical Center of the National Institutes of Health or in local clinics. After informed consent was obtained, family members (n = 844) were examined and photographed. Blood was obtained for genetic studies; genotyping for CDKN2A and CDK4 was performed. Sequential photographs of melanocytic lesions were taken as part of the clinical evaluations. When melanocytic lesions were removed, the histology was reviewed. Representative photographs and photomicrographs were selected for six classes of lesions and three mutation groups.

RESULTS

All the families were found to have members with dysplastic nevi and melanoma; 17 had mutations in CDKN2A, 2 had mutations in CDK4, and 14 had no mutations in either gene identified. The majority of dysplastic nevi either remain stable or regress; few change in a manner that should cause concern for melanoma. With careful surveillance, melanomas can be found early.

CONCLUSIONS

The melanomas and dysplastic nevi that were found to occur in the study families did not appear to vary by the type of mutation identified in the families.

Preformulation study of epigallocatechin gallate, a promising antioxidant for topical skin cancer prevention

Epigallocatechin gallate (EGCG) is a potent polyphenolic antioxidant extracted from green tea. Due to its antimutagenic and antitumor activities, it is a promising candidate for use in topical formulations for skin cancer prevention. The overall goal of this study was therefore to determine the influence of several factors on the stability of EGCG in solution to obtain information that would facilitate the subsequent development of topical formulations. Our first objective was to determine the influence of pH, temperature, and ionic strength on the aqueous stability of EGCG. A second objective was to determine the stability of EGCG in various solvents in the presence and absence of different antioxidants. A simple and rapid stability indicating high-performance liquid chromatography assay for EGCG was developed. Stability studies were performed in 0.05 M aqueous buffers at pH 3, 5, 7, and 9 at 4, 25, and 50 degrees C. The effect of ionic strength on EGCG stability was evaluated in 0.05 M acetate buffer, pH 5, adjusted to the desired ionic strength with sodium chloride. An accelerated stability study of EGCG was performed at 50 degrees C in the organic solvents glycerin and Transcutol P in the presence of antioxidants. The degradation of EGCG increased rapidly as temperature and solution pH were increased. Ionic strength increases also caused an accelerated degradation. The solution stability of EGCG was prolonged in glycerin and Transcutol P compared with an aqueous environment. The addition of 0.1% concentrations of several antioxidants in combination with 0.025% EDTA caused variable effects on EGCG stability. Butylated hydroxytoluene in glycerin produced the greatest stability improvement for EGCG. The t(90) (time for 10% degradation to occur) was 76.1 days at 50 degrees C. It can be concluded that glycerin-based vehicles are suitable for stabilizing EGCG.

Benefit and risk of organic ultraviolet filters

Modern sunscreen products provide broad-spectrum UV protection and may contain one or several UV filters. A modern UV filter should be heat and photostable, water resistant, nontoxic, and easy to formulate. Identification of a substance that meets these criteria is as difficult as discovering a new drug; hundreds of new molecules are synthesized and screened before a lead candidate is identified. The most important aspect in the development of a new UV filter is its safety. In our laboratories, the safety of new ultraviolet filters is assessed by an initial in vitro screen including photostability, cytotoxicity, photocytotoxicity, genotoxicity, and photogenotoxicity tests. These tests are performed in mammalian, yeast, and bacterial cell systems. Skin penetration potential is measured in vitro using human skin or, when required by regulations, in vivo. Because modern sunscreens are selected on the basis of their retention on and in the stratum corneum and are formulated as poorly penetrating emulsions, they generally have very low to negligible penetration rates. The safety and efficacy of UV filters are regulated and approved by national and international health authorities. Safety standards in the European Union, United States, or Japan stipulate that new filters pass a stringent toxicological safety evaluation prior to approval. The safety dossier of a new UV filter resembles that of a new drug and includes acute toxicity, irritation, sensitization, phototoxicity, photosensitization, subchronic and chronic toxicity, reproductive toxicity, genotoxicity, photogenotoxicity, carcinogenicity, and, in the United States, photocarcinogenicity testing. The margin of safety of new UV filters for application to humans is estimated by comparing the potential human systemic exposure with the no-effect level from in vivo toxicity studies. Only substances with a safe toxicological profile and a margin of safety of at least 100-fold are approved for human use. Finally, prior to marketing, new UV filters undergo stringent human testing to confirm their efficacy as well as the absence of irritation, sensitization, photoirritation, and photosensitization potential in man. UV filters not only protect against acute skin injury, such as sunburn, but also against long-term and chronic skin damage, including cellular DNA damage, photoinduced immune suppression, and, by extension, skin cancer. The protection provided by modern sunscreens against UV-induced skin cancer was shown in animal photocarcinogenicity studies and confirmed by numerous in vitro, animal, and human investigations: UV filters protect the p53 tumor suppressor gene from damage and prevent UV-induced immune suppression. Recent studies suggest that sunscreens protect against precursor lesions of skin cancer, such as actinic keratoses. Additional benefits of ultraviolet filters include prevention of photodermatoses, such as polymorphic light eruption, and, possibly, photoaging. Modern sunscreens are safe for children and adults. Percutaneous penetration and irritation rates of topically applied substances in children and adults are similar. The principal protective measure is to keep children out of the sun and/or to cover them with protective clothes; however, sunscreens are a safe and effective and often the only feasible defense of children against UV radiation. In conclusion, sunscreens are safe protective devices that undergo stringent safety and efficacy evaluation.

Ultraviolet B-induced melanoma in Monodelphis domestica occurs in the absence of alterations in the structure or expression of the p53 gene

Monodelphis domestica, a South American opossum, has been established as a mammalian model for sporadic ultraviolet radiation (UVR)-induced melanoma. Using this model system, we investigated the role of changes in the p53 gene in the development of cutaneous melanocyte-derived lesions. Cutaneous melanocytic hyperplasias, benign melanomas and metastatic primary melanomas, plus affected lymph nodes and visceral organs, were screened for mutations in the Monodelphis p53 gene by single-strand conformation polymorphism analysis and direct sequencing. With the exception of a silent point mutation found in a single benign melanocytic hyperplasia sample, no p53 mutations were detected. Furthermore, a relative quantitative reverse transcriptase-polymerase chain reaction approach was used to analyse p53 gene expression at different stages of primary melanoma progression and revealed no substantial changes in p53 mRNA levels. These results suggest that, as in humans, UVR-induced melanoma in the Monodelphis model is initiated and progresses on the basis of predominantly p53-independent molecular pathways.

Multi-waveband solar irradiance on tree-shaded vertical and horizontal surfaces: cloud-free and partly cloudy skies

Irradiance measurements of short wave (SW), photosynthetically active (PAR), ultraviolet-A (UVA) and ultraviolet-B (UVB) solar radiations were made on horizontal and vertical surfaces in the shade of trees under cloud-free and partly cloudy skies. All measurements were referenced to the irradiance of a horizontal surface above the canopy. For horizontal shaded surfaces under cloud-free skies, the values of the ratio (Rh) of below- to above-canopy horizontal irradiance were similar for the UVA and UVB wavebands and for the SW and PAR wavebands. However, Rh for the UV wavebands differed from that for the PAR and SW wavebands. Overall, values of Rh in the shade typically varied as PAR < SW << UVA < UVB. The irradiance ratios for vertical surface in the shade typically varied as UVB > UVA = SW > PAR. In absolute terms, UVB irradiance (Ih) on tree-shaded horizontal surfaces increased relative to a cloud-free sky when a translucent cirroform cloud was in front of the sun, but decreased when the cloud was in a region of sky away from the sun. Translucent cirroform cloud cover also tended to decrease the UVB irradiance (Iv) for a shaded vertical surface (either facing the sun or south) relative to that under cloud-free skies, regardless of where the clouds were in the sky. In all other wavebands the shaded Ih and Iv increased under translucent cirroform cloud cover relative to cloud-free skies, regardless of where the clouds were in the sky.