Melanoma chemoprevention

Deciphering UV-induced DNA Damage Responses to Prevent and Treat Skin Cancer

Ultraviolet (UV) radiation is among the most prevalent environmental factors that influence human health and disease. Even 1 h of UV irradiation extensively damages the genome. To cope with resulting deleterious DNA lesions, cells activate a multitude of DNA damage response pathways, including DNA repair. Strikingly, UV-induced DNA damage formation and repair are affected by chromatin state. When cells enter S phase with these lesions, a distinct mutation signature is created via error-prone translesion synthesis. Chronic UV exposure leads to high mutation burden in skin and consequently the development of skin cancer, the most common cancer in the United States. Intriguingly, UV-induced oxidative stress has opposing effects on carcinogenesis. Elucidating the molecular mechanisms of UV-induced DNA damage responses will be useful for preventing and treating skin cancer with greater precision. Excitingly, recent studies have uncovered substantial depth of novel findings regarding the molecular and cellular consequences of UV irradiation. In this review, we will discuss updated mechanisms of UV-induced DNA damage responses including the ATR pathway, which maintains genome integrity following UV irradiation. We will also present current strategies for preventing and treating nonmelanoma skin cancer, including ATR pathway inhibition for prevention and photodynamic therapy for treatment.

Chemoprevention agents for melanoma: A path forward into phase 3 clinical trials

Recent progress in the treatment of advanced melanoma has led to unprecedented improvements in overall survival and, as these new melanoma treatments have been developed and deployed in the clinic, much has been learned about the natural history of the disease. Now is the time to apply that knowledge toward the design and clinical evaluation of new chemoprevention agents. Melanoma chemoprevention has the potential to reduce dramatically both the morbidity and the high costs associated with treating patients who have metastatic disease. In this work, scientific and clinical melanoma experts from the national Melanoma Prevention Working Group, composed of National Cancer Trials Network investigators, discuss research aimed at discovering and developing (or repurposing) drugs and natural products for the prevention of melanoma and propose an updated pipeline for translating the most promising agents into the clinic. The mechanism of action, preclinical data, epidemiological evidence, and results from available clinical trials are discussed for each class of compounds. Selected keratinocyte carcinoma chemoprevention studies also are considered, and a rationale for their inclusion is presented. These data are summarized in a table that lists the type and level of evidence available for each class of agents. Also included in the discussion is an assessment of additional research necessary and the likelihood that a given compound may be a suitable candidate for a phase 3 clinical trial within the next 5 years.

Evaluation of Biodistribution of Sulforaphane after Administration of Oral Broccoli Sprout Extract in Melanoma Patients with Multiple Atypical Nevi

Broccoli sprout extract containing sulforaphane (BSE-SFN) has been shown to inhibit ultraviolet radiation-induced damage and tumor progression in skin. This study evaluated the toxicity and potential effects of oral BSE-SFN at three dosages. Seventeen patients who each had at least 2 atypical nevi and a prior history of melanoma were randomly allocated to 50, 100, or 200 μmol oral BSE-SFN daily for 28 days. Atypical nevi were photographed on days 1 and 28, and plasma and nevus samples were taken on days 1, 2, and 28. Endpoints assessed were safety, plasma and skin sulforaphane levels, gross and histologic changes, IHC for phospho-STAT3(Y705), Ki-67, Bcl-2, HMOX1, and TUNEL, plasma cytokine levels, and tissue proteomics. All 17 patients completed 28 days with no dose-limiting toxicities. Plasma sulforaphane levels pooled for days 1, 2, and 28 showed median postadministration increases of 120 ng/mL for 50 μmol, 206 ng/mL for 100 μmol, and 655 ng/mL for 200 μmol. Median skin sulforaphane levels on day 28 were 0.0, 3.1, and 34.1 ng/g for 50, 100, and 200 μmol, respectively. Plasma levels of proinflammatory cytokines decreased from day 1 to 28. The tumor suppressor decorin was increased from day 1 to 28. Oral BSE-SFN is well tolerated at daily doses up to 200 μmol and achieves dose-dependent levels in plasma and skin. A larger efficacy evaluation of 200 μmol daily for longer intervals is now reasonable to better characterize clinical and biological effects of BSE-SFN as chemoprevention for melanoma. Cancer Prev Res; 11(7); 429-38. ©2018 AACR.

Inhibiting STAT3 signaling is involved in the anti-melanoma effects of a herbal formula comprising Sophorae Flos and Lonicerae Japonicae Flos

A herbal formula (SL) comprising Sophorae Flos and Lonicerae Japonicae Flos was traditionally used to treat melanoma. Constitutively active signal transducer and activator of transcription 3 (STAT3) has been proposed as a therapeutic target in melanoma. Here we investigated whether an ethanolic extract of SL (SLE) exerted anti-melanoma activities by inhibiting STAT3 signaling. B16F10 allograft model, A375 and B16F10 cells were employed to assess the in vivo and in vitro anti-melanoma activities of SLE. A375 cells stably expressing STAT3C, a constitutively active STAT3 mutant, were used to determine the role of STAT3 signaling in SLE’s anti-melanoma effects. Intragastric administration of SLE (1.2 g/kg) potently inhibited melanoma growth in mice and inhibited STAT3 phosphorylation in the tumors. In cultured cells, SLE dramatically reduced cell viability, induced apoptosis, suppressed migration and invasion, and restrained STAT3 activation and nuclear localization. STAT3C overexpression in A375 cells diminished SLE’s effects on cell viability, apoptosis and invasion. Collectively, SLE exerted potent anti-melanoma effects partially by inhibiting STAT3 signaling. This study provides pharmacological justification for the traditional use of this formula in treating melanoma, and suggests that SLE has the potential to be developed as a modern alternative and/or complimentary agent for melanoma treatment and prevention.

STAT3 targeting by polyphenols: Novel therapeutic strategy for melanoma

Melanoma or malignant melanocytes appear with the low incidence rate, but very high mortality rate worldwide. Epidemiological studies suggest that polyphenolic compounds contribute for prevention or treatment of several cancers particularly melanoma. Such findings motivate to dig out novel therapeutic strategies against melanoma, including research toward the development of new chemotherapeutic and biologic agents that can target the tumor cells by different mechanisms. Recently, it has been found that signal transducer and activator of transcription 3 (STAT3) is activated in many cancer cases surprisingly. Different evidences supply the aspect that STAT3 activation plays a vital role in the metastasis, including proliferation of cells, survival, invasion, migration, and angiogenesis. This significant feature plays a vital role in various cellular processes, such as cell proliferation and survival. Here, we reviewed the mechanisms of the STAT3 pathway regulation and their role in promoting melanoma. Also, we have evaluated the emerging data on polyphenols (PPs) specifically their contribution in melanoma therapies with an emphasis on their regulatory/inhibitory actions in relation to STAT3 pathway and current progress in the development of phytochemical therapeutic techniques. An understanding of targeting STAT3 by PPs brings an opportunity to melanoma therapy. © 2016 BioFactors, 43(3):347-370, 2017.

Melanoma

Melanoma is a common cancer in the Western world with an increasing incidence. Sun exposure is still considered to be the major risk factor for melanoma. The prognosis of patients with malignant (advanced-stage) melanoma differs widely between countries, but public campaigns advocating early detection have led to significant reductions in mortality rates. As well as sun exposure, distinct genetic alterations have been identified as associated with melanoma. For example, families with melanoma who have germline mutations in CDKN2A are well known, whereas the vast majority of sporadic melanomas have mutations in the mitogen-activated protein kinase cascade, which is the pathway with the highest oncogenic and therapeutic relevance for this disease. BRAF and NRAS mutations are typically found in cutaneous melanomas, whereas KIT mutations are predominantly observed in mucosal and acral melanomas. GNAQ and GNA11 mutations prevail in uveal melanomas. Additionally, the PI3K-AKT-PTEN pathway and the immune checkpoint pathways are important. The finding that programmed cell death protein 1 ligand 1 (PDL1) and PDL2 are expressed by melanoma cells, T cells, B cells and natural killer cells led to the recent development of programmed cell death protein 1 (PD1)-specific antibodies (for example, nivolumab and pembrolizumab). Alongside other new drugs - namely, BRAF inhibitors (vemurafenib and dabrafenib) and MEK inhibitors (trametinib and cobimetinib) - these agents are very promising and have been shown to significantly improve prognosis for patients with advanced-stage metastatic disease. Early signs are apparent that these new treatment modalities are also improving long-term clinical benefit and the quality of life of patients. This Primer summarizes the current understanding of melanoma, from mechanistic insights to clinical progress. For an illustrated summary of this Primer, visit: http://go.nature.com/vX2N9s.

Statin use and its effect on all-cause mortality of melanoma patients: a population-based Dutch cohort study

Preclinical data showed anticancer effects of statins in melanoma, but meta-analyses could not demonstrate a reduced melanoma incidence in statin users. Rather than preventing occurrence, statins might reduce growth and metastatic spread of melanomas and ultimately improve survival. In this population-based study, we investigated the relationship between statin use and survival of melanoma patients. Patients ≥18 years who were diagnosed with cutaneous melanoma (Breslow thickness >1 mm) and registered in the Eindhoven Cancer Registry and in PHARMO Database Network between 1 January 1998 and 31 December 2010 were eligible. The hazard ratio (HR) of all-cause mortality was calculated by employing adjusted time-dependent and time-fixed Cox proportional hazard models. Disease-specific survival was estimated by means of 3-year relative survival rates (RSR). A control cohort of randomly selected patients using statins from PHARMO Database Network matched on age and gender was used to compare RSR of statin users to the general population. After melanoma diagnosis, 171 of 709 patients used statins. Use of statins showed a nonsignificantly decreased hazard of death (adjusted HR 0.76, 95% confidence interval [CI] 0.50–1.61). After stratification for gender, male but not female statin users showed a favorable outcome compared to nonusers (HR 0.57, 95% CI 0.32–0.99; HR 1.22, 95% CI 0.62–2.38, respectively). Three-year RSR for male statin users tended to be higher than for nonusers (91% vs. 80.5%, P = 0.06), no differences were observed in women (87.1% vs. 92.5%, P = 0.76). Statin use was not associated with an improved survival of melanoma patients. The trend for better survival of male in contrast to female statin users warrants further research.

Aspirin and other NSAIDs as chemoprevention agents in melanoma

Melanoma incidence is increasing and, despite recent therapeutic advances, the prognosis for patients with metastatic disease remains poor. Thus, early detection and chemoprevention are promising strategies for improving patient outcomes. Aspirin (acetylsalicylic acid) and other nonsteroidal anti-inflammatory drugs (NSAID) have demonstrated chemoprotective activity in several other cancers, and have been proposed as chemopreventive agents for melanoma. Throughout the last decade, however, a number of case-control, prospective, and interventional studies of NSAIDs and melanoma risk have yielded conflicting results. These inconsistent findings have led to uncertainty about the clinical utility of NSAIDs for melanoma chemoprevention. This mini-review highlights current knowledge of NSAID mechanisms of action and rationale for use in melanoma, provides a comparative review of outcomes and limitations of prior studies, and discusses the future challenges in demonstrating that these drugs are effective agents for mitigating melanoma risk.

Chemoprevention of skin melanoma: facts and myths

Melanoma is the most dangerous type of skin cancer. Despite the rise of public awareness, the incidence rate among the white population has been rising constantly for several decades. Systematic improvement in knowledge about the biology of pigment cells and molecular mechanisms of their neoplastic transformation has enhanced the possibility of melanoma chemoprevention. Hence, chemopreventive agents that prevent, inhibit, or reverse melanoma development are being investigated intensively. Among synthetic compounds, especially well studied are lipid-lowering drugs and cyclooxygenase inhibitors. Substances found in everyday diet, such as genistein, apigenin, quercetin, resveratrol, and curcumin may also have potential chemopreventive qualities. However, studies examining the chemopreventive activity of these compounds have shown widely varying results. Early reports on the possible chemopreventive activity of statins and fibrates were not proved by the results of randomized clinical trials. Similarly, case-control studies examining the influence of NSAIDs on the risk of melanoma do not confirm the antitumor activity of cyclooxygenase inhibitors. Further clinical trials involving carefully selected target populations as well as the identification of specific biomarkers of prognostic and predictive value seem to be essential for the evaluation of the chemopreventive activity of the studied substances.

Comparative study of the hydrolytic metabolism of methyl-, ethyl-, propyl-, butyl-, heptyl- and dodecylparaben by microsomes of various rat and human tissues

Hydrolytic metabolism of methyl-, ethyl-, propyl-, butyl-, heptyl- and dodecylparaben by various tissue microsomes and plasma of rats, as well as human liver and small-intestinal microsomes, was investigated and the structure-metabolic activity relationship was examined. Rat liver microsomes showed the highest activity toward parabens, followed by small-intestinal and lung microsomes. Butylparaben was most effectively hydrolyzed by the liver microsomes, which showed relatively low hydrolytic activity towards parabens with shorter and longer alkyl side chains. In contrast, small-intestinal microsomes exhibited relatively higher activity toward longer-side-chain parabens, and showed the highest activity towards heptylparaben. Rat lung and skin microsomes showed liver-type substrate specificity. Kidney and pancreas microsomes and plasma of rats showed small-intestinal-type substrate specificity. Liver and small-intestinal microsomal hydrolase activity was completely inhibited by bis(4-nitrophenyl)phosphate, and could be extracted with Triton X-100. Ces1e and Ces1d isoforms were identified as carboxylesterase isozymes catalyzing paraben hydrolysis by anion exchange column chromatography of Triton X-100 extract from liver microsomes. Ces1e and Ces1d expressed in COS cells exhibited significant hydrolase activities with the same substrate specificity pattern as that of liver microsomes. Small-intestinal carboxylesterase isozymes Ces2a and Ces2c expressed in COS cells showed the same substrate specificity as small-intestinal microsomes, being more active toward longer-alkyl-side-chain parabens. Human liver microsomes showed the highest hydrolytic activity toward methylparaben, while human small-intestinal microsomes showed a broadly similar substrate specificity to rat small-intestinal microsomes. Human CES1 and CES2 isozymes showed the same substrate specificity patterns as human liver and small-intestinal microsomes, respectively.

Selenium for the prevention of cutaneous melanoma

The role of selenium (Se) supplementation in cancer prevention is controversial; effects often depend on the nutritional status of the subject and on the chemical form in which Se is provided. We used a combination of in vitro and in vivo models to study two unique therapeutic windows for intervention in the process of cutaneous melanomagenisis, and to examine the utility of two different chemical forms of Se for prevention and treatment of melanoma. We studied the effects of Se in vitro on UV-induced oxidative stress in melanocytes, and on apoptosis and cell cycle progression in melanoma cells. In vivo, we used the HGF transgenic mouse model of UV-induced melanoma to demonstrate that topical treatment with l-selenomethionine results in a significant delay in the time required for UV-induced melanoma development, but also increases the rate of growth of those tumors once they appear. In a second mouse model, we found that oral administration of high dose methylseleninic acid significantly decreases the size of human melanoma xenografts. Our findings suggest that modestly elevation of selenium levels in the skin might risk acceleration of growth of incipient tumors. Additionally, certain Se compounds administered at very high doses could have utility for the treatment of fully-malignant tumors or prevention of recurrence.

Emerging phytochemicals for prevention of melanoma invasion

Cutaneous malignant melanoma is the leading cause of death from skin diseases due to its propensity to metastasize. Once diagnosed with metastatic melanoma, most patients will die of their disease within 2years. As suppression of metastases requires long-term interventions, potential anti-metastatic agents must not only be efficacious but also have low toxicity. Many phytochemicals used in traditional medicine have low toxicity and recent studies suggest that some are promising candidates for the prevention or treatment of metastatic melanoma. Here, we review the recent literature regarding phytochemicals that have shown inhibitory effects on melanoma cell migration or invasion.

Melanoma: epidemiology, diagnosis, treatment, and outcomes

Melanoma is a skin cancer that arises from the malignant transformation of melanocytes. Although it is typically considered a pigmented lesion, the clinical presentation of melanoma can vary greatly. With increased efforts in screening and detection of early-stage melanoma, researchers and clinicians hope to improve clinical outcomes for patients with melanoma. Novel immunotherapies directed at specific molecular targets in the pathogenesis of melanoma usher in a new era of treatment of advanced melanoma.

Melanoma prevention using topical PBISe

Malignant melanoma is the deadliest form of skin cancer, known for its drug resistance and high metastatic potential. Deregulated PI3 and mitogen activated protein (MAP) kinase pathways promote early melanocytic lesion development and confer drug resistance. No agent exists to target these deregulated pathways to prevent cutaneous noninvasive melanocytic cells or invasive melanomas from developing into more aggressive widely disseminated metastatic disease. In this study, a selenium containing isosteric analogue of PBIT [S, S'-1,4-phenylenebis(1,2-ethanediyl)bis-isothiourea] called PBISe [Se, Se'-1,4-phenylenebis(1,2-ethanediyl)bis-isoselenourea] is shown to moderate these 2 major signaling pathways to prevent cutaneous melanocytic lesion or melanoma development. Topical application of PBISe retarded melanocytic lesion development in laboratory-generated skin by 70% to 80% and in animal skin by approximately 50%. Mechanistically, prevention of lesion development occurred due to decreased Akt3 signaling, which increased MAP kinase pathway activity to inhibitory levels. The combined effect of targeting these pathways led to decreased cell proliferation and increased apoptotic cell death thereby preventing melanoma development. Thus, topically applied PBISe treatment has potential to prevent noninvasive melanocytic lesion and invasive metastatic melanoma development in skin.

Botanicals for the prevention and treatment of cutaneous melanoma

Cutaneous melanoma, a cancer of melanocytes, when detected at later stages is arguably one of the most lethal cancers and the cause of more years of lost life than any other cancer among young adults. There is no standard therapy for advanced-stage melanoma and the median survival time for patients with metastatic melanoma is <1 yr. An urgent need for novel strategies against melanoma has directed research towards the development of new chemotherapeutic and biologic agents that can target the tumor by several different mechanisms. Recently, several dietary agents are being investigated for their role in the prevention and treatment of various forms of cancer and may represent the future modality of the treatment. Here, we have reviewed emerging data on botanicals that are showing promise for their potential inhibitory effect against cutaneous melanoma.

Laser-assisted topical drug delivery by using a low-fluence fractional laser: imiquimod and macromolecules

The aim of this study was to evaluate the ability of a low-fluence fractional erbium:yttrim-aluminum-garnet (Er:YAG) laser, with a wavelength of 2940 nm, for enhancing and controlling the skin permeation of imiquimod and macromolecules such as polypeptides and fluorescein isothiocyanate (FITC)-labeled dextran (FD). The in vitro permeation has been determined using a Franz diffusion cell, with porcine skin and nude mouse skin as the barriers. Hyperproliferative and ultraviolet (UV)-irradiated skins were also used as barrier models to mimic the clinical therapeutic conditions. Confocal laser scanning microscopy (CLSM) was used to examine the in vivo nude mouse skin uptake of peptide, FITC, and FD. Both in vitro and in vivo results indicated an improvement in permeant skin delivery by the laser. The laser fluence and number of passes were found to play important roles in controlling drug transport. Increases of 46- and 127-fold in imiquimod flux were detected using the respective fluences of 2 and 3 J/cm(2) with 4 pulses. An imiquimod concentration of 0.4% from aqueous vehicle with laser treatment was sufficient to approximate the flux from the commercial cream with an imiquimod dose of 5% without laser treatment, indicating a reduction of the drug dose by 125-fold. The enhancement of peptide permeation was size and sequence dependent, with the smaller molecular weight (MW) and more-hydrophilic entities showing greater enhancing effect. Skin permeation of FD with an MW of at least 150 kDa could be achieved with fractional laser irradiation. CLSM images revealed intense green fluorescence from the permeants after exposure of the skin to the laser. The follicular pathway was significant in laser-assisted permeation.

Nuclear accumulation of beta-catenin protein indicates activation of wnt signaling in chemically induced rat nephroblastomas

Aberrant wnt signaling caused by mutations in CTNNB1 occurs in about 15% of Wilms tumors, and these mutations appear to be dependent on the concomitant mutational inactivation of the zinc-finger protein WT1. Nuclear beta-catenin protein, a substitute marker of active wnt signaling, has been detected in an even higher proportion (>50%) of Wilms tumors, suggesting alternative genetic pathways leading to beta-catenin activation. Thus, targeting wnt signaling may become an important future therapeutic strategy in Wilms tumor patients. Currently, chemically induced rat nephroblastomas provide the only available rodent model for this tumor. To determine the contribution of active wnt signaling in this model, we investigated 24 chemically induced rat nephroblastomas for beta-catenin protein expression and for Ctnnb1 and WT1 mutations. Immunohistochemistry showed focal strong nuclear accumulation of beta-catenin protein in 18 of 24 tumors, although in a heterogenous pattern. Blastemal and mesenchymal compartments displayed nuclear-positive cells more frequently than areas of epithelial differentiation. Interestingly, we found no mutation of exon 3 of Ctnnb1 and no mutation within the zinc-finger region of WT1 in any of the 24 tumors analyzed. In conclusion, our findings suggest activation of wnt signaling in the majority (63%) of chemically induced rat nephroblastomas. Nuclear expression of beta-catenin in the absence of Ctnnb1 mutations implies, however, alternate mutational targets in rat nephroblastomas.

Use of oral N-acetylcysteine for protection of melanocytic nevi against UV-induced oxidative stress: towards a novel paradigm for melanoma chemoprevention

PURPOSE

Induction of oxidative stress has been implicated in UV-induced melanoma. We sought to determine whether the antioxidant N-acetylcysteine (NAC) could be safely administered to protect melanocytic nevi from the oxidative stress resulting from acute UV exposure.

EXPERIMENTAL DESIGN

Patients at increased risk for melanoma were recruited from a screening clinic. Induction and detection of oxidative stress (reactive oxygen species and glutathione depletion) was optimized in nevi following ex vivo UV irradiation. Nevi were removed from patients before, and following, oral ingestion of a single (1,200 mg) dose of NAC, and then these nevi were UV irradiated (4,000 J/m(2)).

RESULTS

Oxidative stress was induced in nevi 24 to 48 hours following ex vivo UV irradiation. A single oral dose of NAC was well tolerated in all patients (n = 72). Basal levels of reduced glutathione and the NAC metabolite cysteine were well correlated between similar-appearing nevi from the same patient and were significantly increased in nevi removed 3 hours after NAC ingestion compared with nevi removed before drug ingestion. In approximately half (9 of 19) of patients tested, UV-induced glutathione depletion was attenuated in the postdrug (compared with predrug) nevus.

CONCLUSIONS

NAC can be safely administered to patients for the purpose of modulating UV-induced oxidative stress in nevi. This study suggests the feasibility of patients taking NAC prophylactically before acute UV exposure, to prevent pro-oncogenic oxidative stress in nevi and ultimately reduce long-term melanoma risk.

Can statin therapy reduce the risk of melanoma? A meta-analysis of randomized controlled trials

A growing body of literature suggests that statins may have a chemopreventive potential against melanoma through pleiotropic anti-inflammatory, immunomodulatory, and antiangiogenesis mechanisms. Our aim was to examine this association through a detailed meta-analysis of randomized controlled trials (RCTs). A comprehensive search for trials published up to June 2009 was performed, reviews of each study were conducted and data were abstracted. Prior to meta-analysis, the studies were evaluated for publication bias and heterogeneity. Pooled relative risk estimates (RR) and 95% confidence intervals (CIs) were calculated using the fixed- and the random-effects models. Subgroup and sensitivity analyses were also conducted. Sixteen RCTs of statins for cardiovascular outcomes, involving 62,568 individuals with a mean age of 60 years and an average follow-up of nearly 4.7 years, contributed to the analysis. We found no evidence of publication bias (P = 0.47) or heterogeneity among the studies (P = 0.25). Statin use did not significantly affect the risk of developing melanoma assuming either a fixed- (RR = 0.92, 95% CI: 0.67-1.26), or a random-effects model (RR = 0.92, 95% CI: 0.62-1.36). This neutral effect was further supported by the results of subgroup and sensitivity analyses. Our findings do not support a protective effect of statins against melanoma.

Intravenous administration of CP-4055 (ELACYT) in patients with solid tumours. A Phase I study

PURPOSE

Cytarabine (ara-C) has limited activity in solid tumours. CP-4055 (ELACYT) is a novel ara-C-5'-elaidic acid ester that may circumvent this limitation. CP-4055 maximum tolerated dose (MTD), pharmacokinetics and antitumor activity have been investigated in patients with solid tumours.

MATERIAL AND METHODS

Thirty-four patients (19 malignant melanoma, 8 ovarian cancers and 7 NSCLC) received CP-4055 as a 30 min, or 2 hr intravenous (IV) infusion daily for 5 consecutive days every 3 or 4 weeks (D1-5 q3w or D1-5 q4w) in a dose escalation designed study with doses ranging from 30 to 240 mg/m(2)/day.

RESULTS

The most frequent CTC grade 1-2 adverse events (AEs) were nausea, fatigue, vomiting, anorexia and pyrexia. Most of the grade 3-4 AEs were neutropenia. The MTD was 200 mg/m(2)/day and 240 mg/m(2)/day for D1-5 q3w and D1-5 q4w, respectively. The MTD was independent of infusion time in the 4 week schedule. CP-4055 was maintained in plasma for up to 5-10 hr at dose levels >150 mg/m(2)/day. One objective partial response (PR) with time to progression (TTP) of 22 months was reported in an advanced malignant melanoma patient.

CONCLUSION

CP-4055 was well tolerated; the majority of the AEs were of CTC grade 1. The 3 week schedule was not recommended due to neutropenic nadir between days 18-26. The recommended dose was 200 mg/m(2)/day in a D1-5 q4w schedule. Efficacy data suggest that CP-4055 might be active in treatment of solid tumours.

[Precancerous and early invasive carcinomas: non-surgical treatment of head and facial skin]

Chronic exposure to sunlight with its high proportion of high energy ultraviolet light is the main cause of the common cutaneous precancerous lesions and carcinomas of the head and neck. This causes a field cancerization effect frequently with multiple actinic keratoses (AKs), basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs). Although demonstrating the best cure rates and lowest recurrence rates, surgical excision rapidly progresses to its limits. Field cancerization requires field therapy. Non-specific caustic agents may remove superficial lesions, however, the modern therapeutic modalities such as topical cytotoxic treatment with 5-fluorouracil, photodynamic therapy with 5-aminolevulinic acid (ALA) or its methyl ester (MeALA), the topical immune response modifier imiquimod or the local application of the cyclooxygenase inhibitor diclofenac are more specific and effective. Intralesional and perilesional injections of cytotoxic agents and interferons as well as the new targeted anti-cancer drugs are further alternatives. The most important aspect, however, is the prophylaxis of chronic photodamage.

Adaptation of the protocol for determining in vitro the sun protection factor of anti-solar sticks

Apart from the protection offered by clothing, the application of sunscreen products suited to each type of skin constitutes one way for decreasing the frequency of skin cancers nowadays. After having adapted an in vitro method for determining the efficacy of sunscreens in emulsion form, we wished to transpose this technique by adapting it for the anti-solar sticks for the evaluation of sun protection factor (SPF) using a spectrophotometer equipped with an integrating sphere. To do this, we tested 14 products in the market as well as sticks that we ourselves fabricated in the laboratory. In a base common to all of these sticks, we added organic (13 filters tested) and inorganic (two filters tested, titanium dioxide and zinc oxide) to their maximum permitted concentration in the European Union. In parallel, emulsions containing the same filters at the same percentage of use were studied; to be in keeping with the results on the products packaging on the one hand, and with the results obtained for the emulsion form on the other hand, we were able to determine the optimal mass which needed to be placed on the support used the in vitro test to determine the SPF.

Gamma-IFN-inducible-lysosomal thiol reductase modulates acidic proteases and HLA class II antigen processing in melanoma

HLA class II-restricted antigen (Ag) processing and presentation are important for the activation of CD4+ T cells, which are the central orchestrating cells of immune responses. The majority of melanoma cells either expresses, or can be induced to express, HLA class II proteins. Thus, they are prime targets for immune mediated elimination by class II-restricted CD4+ T cells. We have previously shown that human melanoma cells lack an important enzyme, gamma interferon-inducible lysosomal thiol-reductase (GILT), capable of perturbing immune recognition of these tumors. Here, we show that GILT expression in human melanoma cells enhances Ag processing and presentation via HLA class II molecules. We also show that GILT expression influences the generation of active forms of cysteinyl proteases, cathepsins B, L and S, as well as an aspartyl protease cathepsin D in melanoma cells. Mechanistic studies revealed that GILT does not regulate acidic cathepsins at the transcriptional level; rather it colocalizes with the cathepsins and influences HLA class II Ag processing. GILT expression in melanoma cells also elevated HLA-DM molecules, which favor epitope loading onto class II in the endolysosomal compartments, enhancing CD4+ T cell recognition. These data suggest that GILT-expressing melanoma cells could prove to be very promising for direct antigen presentation and CD4+ T cell recognition, and may have direct implications for the design of cancer vaccines.

N-acetylcysteine protects melanocytes against oxidative stress/damage and delays onset of ultraviolet-induced melanoma in mice

PURPOSE

UV radiation is the major environmental risk factor for melanoma and a potent inducer of oxidative stress, which is implicated in the pathogenesis of several malignancies. We evaluated whether the thiol antioxidant N-acetylcysteine (NAC) could protect melanocytes from UV-induced oxidative stress/damage in vitro and from UV-induced melanoma in vivo.

EXPERIMENTAL DESIGN

In vitro experiments used the mouse melanocyte line melan-a. For in vivo experiments, mice transgenic for hepatocyte growth factor and survivin, shown previously to develop melanoma following a single neonatal dose of UV irradiation, were given NAC (7 mg/mL; mother's drinking water) transplacentally and through nursing until 2 weeks after birth.

RESULTS

NAC (1-10 mmol/L) protected melan-a cells from several UV-induced oxidative sequelae, including production of intracellular peroxide, formation of the signature oxidative DNA lesion 8-oxoguanine, and depletion of free reduced thiols (primarily glutathione). Delivery of NAC reduced thiol depletion and blocked formation of 8-oxoguanine in mouse skin following neonatal UV treatment. Mean onset of UV-induced melanocytic tumors was significantly delayed in NAC-treated compared with control mice (21 versus 14 weeks; P = 0.0003).

CONCLUSIONS

Our data highlight the potential importance of oxidative stress in the pathogenesis of melanoma and suggest that NAC may be useful as a chemopreventive agent.