Chemoprevention of human skin cancer

Current status of skin cancers with a focus on immunology and immunotherapy

Skin cancer is one of the most widespread cancers, with a significant global health effect. UV-induced DNA damage in skin cells triggers them to grow and proliferate out of control, resulting in cancer development. Two common types of skin cancer include melanoma skin cancer (MSC) and non-melanoma skin cancer (NMSC). Melanoma is the most lethal form of skin cancer, and NMSC includes basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and other forms. The incidence of skin cancer is increasing in part owing to a demographic shift toward an aging population, which is more prone to NMSC, imposing a considerable financial strain on public health services. The introduction of immunostimulatory approaches for cancer cell eradication has led to significant improvements in skin cancer treatment. Over the last three decades, monoclonal antibodies have been used as powerful human therapeutics besides scientific tools, and along with the development of monoclonal antibody production and design procedures from chimeric to humanized and then fully human monoclonal antibodies more than 6 monoclonal antibodies have been approved by the food and drug administration (FDA) and have been successful in skin cancer treatment. In this review, we will discuss the epidemiology, immunology, and therapeutic approaches of different types of skin cancer.

The role of the ubiquitin-proteasome pathway in skin cancer development: 26S proteasome-activated NF-κB signal transduction

The Ubiquitin-Proteasome System plays a central role in signal transduction associated with stress, in the skin in particular by the control of NF-κB pathways. Under normal conditions, the inhibitory protein IκB is phosphorylated by kinases, then ubiquitinated and ends up at the proteasome to be degraded. The present short review discusses recent progress in the inhibition of NF-κB activation by proteasome inhibitors prevents the degradation of protein IκB, which accumulates in the cytosol, and there by the activation of NF-κB. Moreover, would not only limit the expression of adhesion molecules and cytokines involved in metastatic processes, but also increase the sensitivity of cancer cells to apoptosis. Considering this fact, the activity of NF-κB is regulated by the phosphorylation and proteasome-dependent degradation of its inhibitor Iκb. In this scenario, the use of a proteasome inhibitor might be an effective strategy in the treatment of skin cancer with constitutive activation of NF-κB.

A Current Review on Drug Loaded Nanofibers: Interesting and Valuable Platform for Skin Cancer Treatment

BACKGROUND

Nanofibers are used in topical medication for various skin diseases like wound healing, skin cancer and others. Non-melanoma skin cancers (NMSCs) are the most widely distributed diseases in the world, of which 99% of people are affected by either basal cell carcinomas (BCCs) or squamous cell carcinomas (SCCs) of the skin. Skin malignancy is caused by direct sun exposure and regular application of unsafe restorative items on the skin.

OBJECTIVE

This review presents the use of nanofibers in skin cancer treatment and advances made in skin cancer treatment.

METHODS

There are various methods used in the production of nanofibers such as bicomponent extrusion, phase separation, template synthesis, drawing, electrospinning, and others. Electrospinning is the most widely used technique for nanofiber fabrication. The nanofibers are produced in nanometer size range and mostly used in medication because of their low thickness, large surface area per unit mass and porosity. Nanofibers are also used as drug delivery system for sustaining the action of drugs or medicaments.

RESULTS

Nanofibers enhance the permeation and availability of those drugs having low bioavailability and low permeability. Nanofibers increase the sustainability of the drugs up to 10 days.

CONCLUSION

Skin cancer is the abnormal growth of skin cells in the body influencing people of all colours and skin. In this review paper, the definition and production techniques of nanofibers and drugs used in skin cancer treatment and the relation between skin cancer and nanofiber are illustrated in detail. With the help of different techniques and drugs, the risk of non-melanoma skin cancer is reduced. Lay Summary: The risk of skin cancer and other skin problems is increasing day by day. In a previous study we found that the nanofibers are less used as a topical delivery system. We have studied the nanofibers as a drug delivery system in the treatment of skin cancer by using different drugs. According our study nanofibers are most useful in skin drug delivery and if the nanofiber, are merging with other drug delivery system like nanoparticles, it may maximize the output of drug into skin. The significance of this study is, to explain all information about nanofibers in skin cancer.

Antitumor effect of Melaleuca alternifolia essential oil and its main component terpinen-4-ol in combination with target therapy in melanoma models

Essential oils (EOs) have been recently emerging for their promising biological activities in preventing tumorigenesis or progression of different tumor histotypes, including melanoma. In this study, we investigated the antitumor activity of a panel of EOs in different tumor models. The ability of Melaleuca alternifolia (tea tree oil) and its main component, terpinen-4-ol, to sensitize the target therapy currently used for melanoma treatment was also assessed. Our results demonstrated that EOs differently affect the viability of human cancer cells and led us to select six EOs effective in melanoma and lung cancer cells, without toxic effects in human fibroblasts. When combined with dabrafenib and/or trametinib, Melaleuca alternifolia synergistically reduced the viability of melanoma cells by activating apoptosis. Through machine learning classification modeling, α-terpineol, tepinolene, and terpinen-4-ol, three components of Melaleuca alternifolia, were identified as the most likely relevant components responsible for the EO's antitumor effect. Among them, terpinen-4-ol was recognized as the Melaleuca alternifolia component responsible for its antitumor and proapoptotic activity. Overall, our study holds promise for further analysis of EOs as new anticancer agents and supports the rationale for their use to improve target therapy response in melanoma.

Antioxidant and Pro-Oxidant Capacities as Mechanisms of Photoprotection of Olive Polyphenols on UVA-Damaged Human Keratinocytes

A wide variety of polyphenols are reported to have considerable antioxidant and skin photoprotective effects, although the mechanisms of action are not fully known. Environmentally friendly and inexpensive sources of natural bioactive compounds, such as olive mill wastewater (OMWW), the by-product of olive-oil processing, can be considered an economic source of bioactive polyphenols, with a range of biological activities, useful as chemotherapeutic or cosmeceutical agents. Green strategies, such as the process based on membrane technologies, allow to recover active polyphenols from this complex matrix. This study aims to evaluate the antioxidant, pro-oxidant, and photoprotective effects, including the underlying action mechanism(s), of the ultra-filtered (UF) OMWW fractions, in order to substantiate their use as natural cosmeceutical ingredient. Six chemically characterized UF-OMWW fractions, from Italian and Greek olive cultivar processing, were investigated for their antioxidant activities, measured by Trolox Equivalent Antioxidant Capacity (TEAC), LDL oxidation inhibition, and ROS-quenching ability in UVA-irradiated HEKa (Human Epidermal Keratinocytes adult) cultures. The photoprotective properties of UF-OMWW were assayed as a pro-oxidant-mediated pro-apoptotic effect on the UVA-damaged HEKa cells, which can be potentially involved in the carcinogenesis process. All the UF-OMWW fractions exerted an effective antioxidant activity in vitro and in cells when administered together with UV-radiation on HEKa. A pro-oxidative and pro-apoptotic effect on the UVA-damaged HEKa cells were observed, suggesting some protective actions of polyphenol fraction on keratinocyte cell cultures.

Sunscreens and their usefulness: have we made any progress in the last two decades?

Sunscreens have now been around for decades to mitigate the Sun's damaging ultraviolet (UV) radiation which, although essential for the existence of life, is a recognized prime carcinogen. Accordingly, have suncreams achieved their intended purposes towards protection against sunburns, skin photo-ageing and the like? Most importantly, however, have they provided the expected protection against skin cancers that current sunscreen products claim to do? In the last two decades, there have been tens, if not hundreds of studies on sunscreens with respect to skin protection against UVB (280‒320 nm)-traditionally sunscreens with rather low sun protection factors (SPF) were intended to protect against this type of radiation-and UVA (320‒400 nm) radiation; a distinction between SPF and UVA protection factor (UVA-PF) is made. Many of the studies of the last two decades have focused on protection against the more skin-penetrating UVA radiation. This non-exhaustive article reviews some of the important facets of what is currently known about sunscreens with regard (i) to the physical UV filters titanium dioxide (TiO₂) and zinc oxide (ZnO) and the mostly photo-unstable chemical UVB/UVA filters (e.g., octinoxate (OMC) and avobenzone (AVO), among others), (ii) to novel chemical sunscreen agents, (iii) to means that minimize the breakdown of chemical filters and improve their stability when exposed to UV sunlight, (iv) to SPF factors, and (v) to a short discussion on non-melanoma skin cancers and melanoma. Importantly, throughout the article we allude to the safety aspects of sunscreens and at the end ask the question: do active ingredients in sunscreen products pose a risk to human health, and what else can be done to enhance protection? Significant loss of skin protection from two well-known commercial suncreams when exposed to simulated UV sunlight. Cream I: titanium dioxide, ethylhexyl triazone, avobenzone, and octinoxate; Cream II: octyl salicylate, oxybenzone, avobenzone, and octinoxate.

Computational Modeling on Aquaporin-3 as Skin Cancer Target: A Virtual Screening Study

Aquaporin-3 (AQP3) is one of the aquaglyceroporins, which is expressed in the basolateral layer of the skin membrane. Studies have reported that human skin squamous cell carcinoma overexpresses AQP3 and inhibition of its function may alleviate skin tumorigenesis. In the present study, we have applied a virtual screening method that encompasses filters for physicochemical properties and molecular docking to select potential hit compounds that bind to the Aquaporin-3 protein. Based on molecular docking results, the top 20 hit compounds were analyzed for stability in the binding pocket using unconstrained molecular dynamics simulations and further evaluated for binding free energy. Furthermore, examined the ligand-unbinding pathway of the inhibitor from its bound form to explore possible routes for inhibitor approach to the ligand-binding site. With a good docking score, stability in the binding pocket, and free energy of binding, these hit compounds can be developed as Aquaporin-3 inhibitors in the near future.

Nanoparticles for topical drug delivery: Potential for skin cancer treatment

Nanoparticles offer new opportunities for the treatment of skin diseases. The barrier function of the skin poses a significant challenge for nanoparticles to permeate into the tissue, although the barrier is partially compromised in case of injury or inflammation, as in the case of skin cancer. This may facilitate the penetration of nanoparticles. Extensive research has gone into developing nanoparticles for topical delivery; however, relatively little progress has been made in translating them to the clinic for treating skin cancers. We summarize the types of skin cancers and practices in current clinical management. The review provides a comprehensive outlook of the various nanoparticle technologies tested for topical therapy of skin cancers and summarizes the obstacles that impede its progress from the bench-to-bedside. The review also aims to provide an understanding of the pathways that govern nanoparticle penetration into the skin and a critical analysis of the approaches used to study nanoparticle interactions within the tissue.

Proprotein convertases: Key players in inflammation-related malignancies and metastasis

Many cancers occur from locations of inflammation due to chronic irritation and/or infection. Tumor microenvironment contains various different inflammatory cells and mediators that orchestrate diverse neoplastic processes, including proliferation, survival, adhesion and migration. In parallel, tumor cells have adapted some of the signaling molecules used by inflammatory cells, such as selectins and chemokines as well as their receptors for invasion, extravasation and subsequently metastasis. Expression and/or activation of the majority of these molecules is mediated by the proprotein convertases (PCs); proteases expressed by both tumor cells and inflammatory cells. This review analyzes the potential role of these enzymatic system in inflammation-associated cancer impacting on the malignant and metastatic potential of cancer cells, describing the possible use of PCs as a new anti-inflammatory therapeutic approach to tumor progression and metastasis.

•

Proteins maturation by the proprotein convertases plays important role in inflammation-related cancer and metastasis.

•

Protein precursors require the proprotein convertases for the induction of inflammation.

•

Understanding of the molecular mechanism linking the proprotein convertases to inflammation will allow novel therapies.

•

Inhibitors of the proprotein convertases constitute great potential for cancer treatment.

The association between nonsteroidal anti-inflammatory drugs and skin cancer: Different responses in American and European populations

OBJECTIVE

To conduct a comprehensive systematic meta-analysis investigating the association of nonsteroidal anti-inflammatory drugs (NSAIDs) and their subtypes with skin cancer (SC) and its subclasses (basal cell carcinoma BCC; squamous cell carcinoma SCC; melanoma; nonmelanoma skin cancer NMSC) in general, American and European populations.

METHODS

PubMed, Embase, the Cochrane Library, the China National Knowledge Infrastructure and ClinicalTrials.gov were searched up to 24 February 2019. Pooled effect sizes and 95% confidence intervals were used to estimate associations.

RESULTS

Results based on 26 original studies including 223,619 cases and 1,398,507 controls showed both NSAIDs and nonselective Cyclooxygenase (COX) inhibitors to be statistically significantly associated with a reduced risk of SC, BCC, SCC and NMSC but not with melanoma. Conversely, no association was observed between selective Cyclooxygenase 2 (COX-2) inhibitors and SC or its subclasses. Further subgroup analysis showed that the results analyzed for American populations were almost the same as those for the general population. For European populations, neither NSAIDs nor its subtypes correlated significantly with susceptibility to SC or its subclasses.

CONCLUSIONS

The use of NSAIDs might reduce the risk of SC, but many factors including study population, drug subtype, and disease subclass affect the significance of the association.

Treatment of actinic keratoses and cancerization field of the face and scalp with 0.015% ingenol mebutate gel in Brazilian individuals: safety, tolerability and patients' perspectives

BACKGROUND

Actinic keratosis (AK) represents a risk of progression to squamous cell carcinoma. Ingenol mebutate gel is a novel therapeutic option for field-directed treatment.

OBJECTIVES

To evaluate the safety, tolerability and patients' perspectives, related to the therapeutic success of managing AKs on the face and scalp with ingenol mebutate gel in Brazilian individuals.

METHODS

This was an observational, retrospective and descriptive study of 68 areas of actinic keratosis on the face and scalp treated with Ingenol mebutate gel involving a total of 37 patients. The drug was applied for three consecutive days on an area of of 25 cm2 and documentation was performed on baseline and days 4, 8, 15, 60 and 180. On day 4, the composite local skin reaction score was calculated. At the end, a questionnaire was applied to evaluate patients' perspectives about the treatment.

RESULTS

Adherence was 100%, no serious adverse events were recorded and the mean composite local skin reaction score (standard deviation) was 8.61±4.22. The treatment was considered optimum by 75.68% of the patients.

STUDY LIMITATIONS

Calculation of composite local skin reaction score performed only on the fourth day.

CONCLUSIONS

Treatment with ingenol mebutate gel was considered safe and tolerable in Brazilian subjects. Patients had a maximum adherence rate and a great improvement in self-esteem. The results of this research reproduce the findings of the literature.

Evaluating the Noninferiority of a New Photodynamic Therapy (Flexitheralight) Compared With Conventional Treatment for Actinic Keratosis: Protocol for a Phase 2 Study

Background

Actinic keratosis (AK) is characterized by preinvasive, cancerous lesions on sun-exposed skin that negatively affect patient quality of life and may progress to invasive squamous cell carcinoma (SCC). If untreated, AK may either regress or progress to SCC, with significant morbidity and possible lethal outcomes. The most commonly used treatments for AK are cryotherapy, topical chemotherapy and, more recently, photodynamic therapy (PDT). This clinical study is part of a project that aims to create specific light-emitting fabrics (LEFs) that strongly improve the efficiency and reliability of PDT as a treatment for AK.

Objective

This study aims to compare the efficacy and tolerability of a new PDT protocol involving the Flexitheralight device (N-PDT) with the classical protocol involving the Aktilite CL 128 device (C-PDT; Galderma Laboratories) for the treatment of AK. All participants receive both protocols. The primary objective of this study is to compare the lesion response rate after 3 months of N-PDT with C-PDT. Secondary objectives are evaluations of pain and local tolerance during treatment, clinical evolution of the subject's skin, and evaluations of patient quality of life and satisfaction.

Methods

The study is a split-face, intraindividual comparison of two PDT protocols. The total number of patients recruited was 42. Patients were exposed to a continuous red light with the Aktilite CL 128 device on one side of the face and to fractionated red illumination with the new device, Flexitheralight, on the other side of the face. Males or females over the age of 18 years with a clinical diagnosis of at least 10 previously untreated, nonpigmented, nonhyperkeratotic grade I and II AK lesions of the forehead and/or scalp were included and were recruited from the Department of Dermatology of the Centre Hospitalier Universitaire de Lille. The patients came to the investigational center for one treatment session (day 1), and they were followed up after 7 days, 3 months and 6 months. A second treatment session was performed on day 111 in cases in which an incomplete response was observed at the 3-month follow-up. Data will be analyzed using SAS software version 9.4 (SAS Institute Inc). Continuous variables will be reported as means and standard deviations, and categorical variables will be reported as frequencies and percentages. The Shapiro-Wilk test will be used to assess the normality of the distribution.

Results

The clinical investigation was performed by July 2018. Data analysis was performed at the end of 2018, and results are expected to be published in early 2019.

Conclusions

This phase II clinical trial aims to evaluate the noninferior efficacy and superior tolerability of N-PDT compared to that of C-PDT. If N-PDT is both efficacious and tolerable, N-PDT could become the treatment of choice for AK due to its ease of implementation in hospitals.

Trial Registration

ClinicalTrials.gov NCT03076918; https://clinicaltrials.gov/ct2/show/NCT03076918 (archived by WebCite at http://www.webcitation.org/771KA0SSK)

International Registered Report Identifier (IRRID)

DERR1-10.2196/11530

Molecular dynamic simulations of oxidized skin lipid bilayer and permeability of reactive oxygen species

Lipid peroxidation by reactive oxygen species (ROS) during oxidative stress is non-enzymatic damage that affects the integrity of biological membrane, and alters the fluidity and permeability. We conducted molecular dynamic simulation studies to evaluate the structural properties of the bilayer after lipid peroxidation and to measure the permeability of distinct ROS. The oxidized membrane contains free fatty acid, ceramide, cholesterol, and 5α-hydroperoxycholesterol (5α-CH). The result of unconstrained molecular dynamic simulations revealed that lipid peroxidation causes area-per-lipid of the bilayer to increase and bilayer thickness to decrease. The simulations also revealed that the oxidized group of 5α-CH (-OOH) moves towards the aqueous layer and its backbone tilts causing lateral expansion of the bilayer membrane. These changes are detrimental to structural and functional properties of the membrane. The measured free energy profile for different ROS (H₂O₂, HO₂, HO, and O₂) across the peroxidized lipid bilayer showed that the increase in lipid peroxidation resulted in breaching barrier decrease for all species, allowing easy traversal of the membrane. Thus, lipid peroxidation perturbs the membrane barrier and imposes oxidative stress resulting into apoptosis. The collective insights increase the understanding of oxidation stress at the atomic level.

Expression of P53, BAX, and BCL-2 in human malignant melanoma and squamous cell carcinoma cells after tea tree oil treatment in vitro

Tea tree oil (TTO) is an essential oil obtained by steam distillation from the leaves of Melaleuca alternifolia (Myrtaceae). This oil has traditionally been used for the treatment of various skin infections. The present study aimed to investigate the cytotoxic effects of TTO against two representative types of human skin cancer, namely malignant melanoma (A-375) and squamous cell carcinoma (HEp-2).To outline the basic molecular mechanism involved in apoptosis induction in A-375 and HEp-2 cell lines, Annexin V/PI staining for apoptosis detection, cell cycle analysis were monitored using flow cytometry and mRNA expression levels of the apoptosis-regulatory genes P53, BAX, and BCL-2 were determined by real-time PCR and western blot after treatment with TTO. Results showed that TTO exhibited a strong cytotoxicity towards A-375 and HEp-2 cell lines, with IC50 values of 0.038% (v/v) and 0.024% (v/v) respectively. This cytotoxicity resulted from TTO induced apoptosis in both A-375 and HEp-2 cell lines as evidenced by morphological features of apoptosis and Annexin V/PI staining results in addition to the activation of caspase-3/7 and -9, upregulation of pro-apoptotic genes (P53 and BAX) and downregulation of the anti-apoptotic gene BCL-2. Additionally, cell cycle analysis showed that TTO caused cell cycle arrest mainly at G2/M phase. Taken together, the results of this study reveal that TTO is an effective apoptosis inducer in A-375 and HEp-2 cancer cell lines, indicating that it could be a promising chemopreventive candidate to be used in topical formulations against melanoma and squamous cell cancers; however, further in vivo studies may be warranted.

DNA scission and LDL cholesterol oxidation inhibition and antioxidant activities of Bael (Aegle marmelos) flower extracts

Phenolic compounds and other antioxidants have been implicated in protection against non-communicable diseases (NCDs) in which oxidative stress is a main contributor. The extracts of Bael (Aegle marmelos) flower were examined for their phenolic content, free radical scavenging efficacy and inhibition of low density lipoprotein (LDL) cholesterol oxidation and DNA scission activities. The extracts of Bael flowers were prepared using different solvent systems and their total phenolic content (TPC) and total flavonoid content (TFC) determined. Selected extracts which showed high TPC were subsequently used to determine their efficacy in scavenging hydroxyl, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, using electron paramagnetic resonance (EPR) spectroscopy. The corresponding peroxyl radical scavenging activity was measured using oxygen radical absorbance capacity (ORAC) assay. The potency of the extracts in inhibiting hydroxyl and peroxyl radical-induced supercoiled DNA scission and inhibition of LDL cholesterol oxidation was also evaluated. The chemical identity of phenolic compounds present in the extracts was tentatively unraveled using HPLC-MS. Phenolic extracts of Bael flowers effectively inhibited hydroxyl, and peroxyl radicals. Phenolic extracts demonstrated notable inhibitory activity against hydroxyl and peroxyl radical-induced DNA scission and LDL oxidation. Vanillic, p-coumaric, chlorogenic, caffeic, and gentisic acids were identified as major phenolic acids, along with flavonoids, mainly catechin, and quercetin. The knowledge gained here may help better use of Bael flower extracts as functional herbal beverage ingredients in the prevention of NCDs.

The protective effect of some Thai plants and their bioactive compounds in UV light-induced skin carcinogenesis

Skin cancer, represents a major public health concern. While the vast majority is non-melanoma skin cancers, melanomas are mostly responsible for mortality. Solar UVB radiation is mutagenic and carcinogenic. It is primarily responsible for both non-melanoma and melanoma skin cancers via excessive production of reactive oxygen species (ROS), which mediate changes in inflammation and immunity, and have been implicated in all three stages of skin cancer development. Due to their regulatory role in numerous functions of cells, signaling pathways are targets for chemoprevention. The current standards in melanoma therapy are targeted and combination therapies, which, albeit prolong survival responses, are still prone to development of drug resistance. To this extent, drugs of natural origin continue to spark great interest. Thailand has a rich biodiversity of indigenous flora, which have traditionally been used to treat a variety of pathologies. The active components in plant extracts that have medicinal properties, termed 'bioactive compounds,' are efficient chemopreventive agents due to their antioxidant, antimutagenic, anticarcinogenic, and carcinogen detoxification properties. Thai plants and their bioactive compounds have shown protective effects on UV light-induced skin cancer in different experimental models. This warrants further in vivo investigations and translation to clinical studies to determine efficacy and safety, for use as lead compounds in targeted/combination therapy or adjuvant therapy with existing regimes. Coupled with a strategy for prevention, this offers a promising outlook for protection against photocarcinogenesis.

Positive regulatory interactions between YAP and Hedgehog signalling in skin homeostasis and BCC development in mouse skin in vivo

Skin is a highly plastic tissue that undergoes tissue turnover throughout life, but also in response to injury. YAP and Hedgehog signalling play a central role in the control of epidermal stem/progenitor cells in the skin during embryonic development, in postnatal tissue homeostasis and in skin carcinogenesis. However, the genetic contexts in which they act to control tissue homeostasis remain mostly unresolved. We provide compelling evidence that epidermal YAP and Hedgehog/GLI2 signalling undergo positive regulatory interactions in the control of normal epidermal homeostasis and in basal cell carcinoma (BCC) development, which in the large majority of cases is caused by aberrant Hedgehog signalling activity. We report increased nuclear YAP and GLI2 activity in the epidermis and BCCs of K14-CreER/Rosa-SmoM2 transgenic mouse skin, accompanied with increased ROCK signalling and ECM remodelling. Furthermore, we found that epidermal YAP activity drives GLI2 nuclear accumulation in the skin of YAP2-5SA-ΔC mice, which depends on epidermal β-catenin activation. Lastly, we found prominent nuclear activity of GLI2, YAP and β-catenin, concomitant with increased ROCK signalling and stromal fibrosis in human BCC. Our work provides novel insights into the molecular mechanisms underlying the interplay between cell signalling events and mechanical force in normal tissue homeostasis in vivo, that could potentially be perturbed in BCC development.

Pharmacoeconomic evaluations in the treatment of actinic keratoses

Actinic keratoses (AKs) develop as a consequence of chronic ultraviolet (UV) exposure and exist on a continuum with squamous cell carcinoma (SCC). As one of the most common conditions treated by dermatologists, AK places a significant burden on patients and the healthcare system. A range of treatments are used, including topical treatments that target the visible and subclinical lesions. The goal of such therapies is to achieve complete clearance of AKs and eliminate the risk of progression to SCC. Robust meta-analyses of trial data can provide valuable information for the optimal management of AK and cost-effectiveness evaluations of topical treatments, such as ingenol mebutate gel and diclofenac. These outcomes can facilitate prescribing physicians’ decisions and shape therapeutic guidelines. Peer-reviewed meta-analysis publications and treatment guidelines favoured ingenol mebutate efficacy over diclofenac and the relative cost-effectiveness of ingenol mebutate. We discuss and critique recent evidence, from a cost-effectiveness analysis of 3% diclofenac sodium and ingenol mebutate in the treatment of AK in Italy, which has challenged this view.

Primary and Secondary Chemoprevention of Malignant Melanoma

The incidence of malignant melanoma (MM) continues to rise in the United States. While sun protection and full body skin examinations remain the mainstay of preventative care, chemoprevention of the deadly disease has become an increasingly popular field of study. In this focused review, we discuss current findings and analyze the risks and benefits of various agents investigated for the primary and secondary chemoprevention of MM. Such agents include topical retinoids, vitamins, and supplements, Polypodium leucotomas extracts, non-steroidal anti-inflammatory agents (NSAIDs), statins, sunscreens, and field therapy with topical imiquimod for primary and secondary chemoprevention. We further identify a need for expanded high quality human research on the topic.

Tumor-Preferential Induction of Immune Responses and Epidermal Cell Death in Actinic Keratoses by Ingenol Mebutate

The rapid and strong clinical efficacy of the first-in-class, ingenol mebutate, against actinic keratosis (AK) has resulted in its recent approval. We conducted the first comprehensive analysis of the cellular and molecular mode of action of topical ingenol mebutate 0.05% gel in both AK and uninvolved skin of 26 patients in a phase I, single-center, open-label, within-patient comparison. As early as 1 day after application, ingenol mebutate induced profound epidermal cell death, along with a strong infiltrate of CD4⁺ and CD8⁺ T-cells, neutrophils, and macrophages. Endothelial ICAM-1 activation became evident after 2 days. The reaction pattern was significantly more pronounced in AK compared with uninvolved skin, suggesting a tumor-preferential mode of action. Extensive molecular analyses and transcriptomic profiling of mRNAs and microRNAs demonstrated alterations in gene clusters functionally associated with epidermal development, inflammation, innate immunity, and response to wounding. Ingenol mebutate reveals a unique mode of action linking directly to anti-tumoral effects.

Trial Registration: ClinicalTrials.gov NCT01387711

A cost-utility analysis of ingenol mebutate gel for the treatment of actinic keratosis: a Scottish perspective

BACKGROUND

Actinic keratosis (AK) is a UV-induced, pre-malignant skin condition that is common in adults over 60 years of age with fair skin in Scotland. The most commonly prescribed first-line treatment for AK in Scotland is currently diclofenac gel (3 %). Ingenol mebutate gel is a recently developed topical therapy available in two strengths for the treatment of AK lesions on the face and scalp (150 mcg/g once daily for 3 consecutive days) or trunk and extremities (500 mcg/g once daily for 2 consecutive days).

OBJECTIVE

To compare the cost-effectiveness of two strengths of ingenol mebutate gel developed to treat AK lesions on the face and scalp (150 mcg/g once daily for 3 consecutive days) or trunk and extremities (500 mcg/g once daily for 2 consecutive days) with other first-line AK therapies including diclofenac gel, 5-FU, 5-FU/salicylic acid, and cryotherapy for the first-line treatment of AK in adult patients, from the perspective of the National Health Service (NHS) in Scotland.

METHODS

A cost-utility analysis was conducted using a decision-tree approach to calculate the costs and benefits of different treatment strategies for AK on the face and scalp or trunk and limbs over a 12-month time horizon. Data on the relative efficacy of treatments were obtained from a systematic literature review and meta-analysis. Utility scores and resource-use data were obtained from published sources.

RESULTS

Over 12 months, ingenol mebutate 150 mcg/g gel and 500 mcg/g gel were cost-effective compared with the most commonly used topical therapy in Scotland, diclofenac (3 %) gel, at a willingness-to-pay threshold of £20,000 per QALY, with a minimal additional cost of £43 and £105, respectively per QALY gained.

CONCLUSIONS

Ingenol mebutate gel is a cost-effective therapy for the first-line treatment of AK from a Scottish NHS perspective.

Anticancer properties of phospholipase A2 from Daboia siamensis venom on human skin melanoma cells

Background

Phospholipase A₂ (PLA₂) is a major component of the Daboia siamensis venom, which is able to hydrolyse the membrane of various cells. For this reason, the activity of PLA₂ was investigated regarding its pharmaceutical properties. This study was conducted to explore the pharmacological properties of a PLA₂ from Daboia siamensis (dssPLA₂) venom on human skin melanoma cell line (SK-MEL-28).

Methods

dssPLA₂ was isolated by ion exchange and gel filtration columns. Various concentrations of dssPLA₂ were investigated for cytotoxic activity and inhibition of migration on SK-MEL-28 cells. Cell death analysis, mRNA expression levels of Notch I-III and BRAF V600E genes were also determined.

Results

dssPLA₂ exhibited cytotoxicity on SK-MEL-28 for 24 and 72 h as compared with untreated cells. However, it had no toxic effects on CCD-1064sk cells under the same conditions. dssPLA₂ (0.25 and 0.5 μg/mL) induced 17.16 and 30.60 % of apoptosis, while activated 6.53 and 7.05 % of necrotic cells. dssPLA₂ at 0.25, 0.5, 1 and 2 μg/mL could inhibit migration on SK-MEL-28 cells for 24 h by 31.06, 41.66, 50 and 68.75 %, respectively. The action of dssPLA₂ significantly reduced the levels of Notch I and BRAF V600E genes expression on SK-MEL-28 cells compared with untreated cells at 72 h.

Conclusions

This study indicates that dssPLA₂ had potential effects of apoptosis, necrosis, cytotoxicity and inhibition of migration on SK-MEL-28 cells. dssPLA₂ could possibly be a selective agent that targets cancer cells without affecting normal cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s40409-016-0061-z) contains supplementary material, which is available to authorized users.

Quality by design case study 1: Design of 5-fluorouracil loaded lipid nanoparticles by the W/O/W double emulsion - Solvent evaporation method

With Quality by Design (QbD), a systematic approach involving design and development of all production processes to achieve the final product with a predetermined quality, you work within a design space that determines the critical formulation and process parameters. Verification of the quality of the final product is no longer necessary. In the current study, the QbD approach was used in the preparation of lipid nanoparticle formulations to improve skin penetration of 5-Fluorouracil, a widely-used compound for treating non-melanoma skin cancer. 5-Fluorouracil-loaded lipid nanoparticles were prepared by the W/O/W double emulsion - solvent evaporation method. Artificial neural network software was used to evaluate the data obtained from the lipid nanoparticle formulations, to establish the design space, and to optimize the formulations. Two different artificial neural network models were developed. The limit values of the design space of the inputs and outputs obtained by both models were found to be within the knowledge space. The optimal formulations recommended by the models were prepared and the critical quality attributes belonging to those formulations were assigned. The experimental results remained within the design space limit values. Consequently, optimal formulations with the critical quality attributes determined to achieve the Quality Target Product Profile were successfully obtained within the design space by following the QbD steps.

Efficacy and safety of follow-up field treatment of actinic keratosis with ingenol mebutate 0·015% gel: a randomized, controlled 12-month study

BACKGROUND

Ingenol mebutate (IngMeb) is a novel patient-applied topical field therapy for actinic keratosis.

OBJECTIVES

To demonstrate the efficacy and safety of follow-up IngMeb field treatment of actinic keratoses (AKs) present at 8 weeks after initial treatment or emerging in a previously cleared field.

METHODS

In this phase III, randomized, double-blind study in patients with 4-8 clinically visible AKs within a contiguous 25-cm(2) treatment area on the face or scalp, all patients were treated initially with IngMeb 0·015% gel for three consecutive days. If lesions were present in the field at 8 weeks, or emerged at weeks 26 or 44, patients were randomized (2 : 1) to follow-up IngMeb or vehicle gel for three consecutive days. The main outcome was complete clearance rates of AKs 8 weeks after randomization.

RESULTS

Of 450 patients who received initial treatment with IngMeb, 61·6% demonstrated complete clearance at 8 weeks. Patients with AKs present at 8 weeks or emerging at weeks 26 or 44 were randomized to IngMeb (n = 134) or vehicle (n = 69). IngMeb achieved a higher complete clearance rate than vehicle 8 weeks after randomization in AKs present at 8 weeks (46·7% vs. 18·4%; P < 0·01) and in emergent AKs (59·5% vs. 25·0%; P = 0·01). Based on those who completed 12 months of follow-up (n = 340), the overall 12-month clearance rate was estimated at 50·0%. Follow-up IngMeb treatment was well tolerated.

CONCLUSIONS

This study demonstrated the long-term benefit of IngMeb 0·015% gel for initial and follow-up therapy of AKs.

A randomized trial comparing simultaneous vs. sequential field treatment of actinic keratosis with ingenol mebutate on two separate areas of the head and body

Background

Actinic keratoses (AKs) are precursors to invasive squamous cell carcinoma and can progress if untreated. Limited data support the use of ingenol mebutate to treat AKs on more than one area of the body simultaneously.

Objective

To investigate safety, efficacy and treatment satisfaction when treating separate areas simultaneously or sequentially with different concentrations of ingenol mebutate gel.

Methods

In this phase IIIb study (NCT01787383), patients with clinically visible, non‐hyperkeratotic AKs on two separate treatment areas (face/scalp and trunk/extremities) were randomized to simultaneous or sequential treatment with ingenol mebutate gel (0.015% and 0.05%). Endpoints included composite local skin response (LSR) score 3 days after first application, complete AK clearance and percentage reduction in AKs at week 8.

Results

There were no statistically significant differences between simultaneous (n = 101) and sequential (n = 98) groups in composite LSR score (10.4 vs. 9.7), complete clearance (52.7% vs. 46.9%) or percentage reduction in AKs (83.4% vs. 79.1%). Mean composite LSR scores on face/scalp and trunk/extremities were similar for both groups. Adverse event (AE) incidence was comparable between groups, the most common treatment‐related AEs being pruritus and pain at the application site.

Conclusion

Treating AKs with ingenol mebutate simultaneously or sequentially gave similar results in terms of tolerability (LSR score, AEs) and efficacy (complete clearance). Therefore, the physician and patient can select the most convenient treatment regimen, with confidence in achieving a similar outcome.

A randomized, double-blind, placebo-controlled clinical trial evaluating Dermytol(®) cream for the treatment of actinic keratoses

Purpose

Actinic keratosis lesions (AKs) have the potential to develop into squamous cell carcinoma (SCC) and thus therapies to prevent SCC development from AKs are warranted. The aim of this study was to assess the effects of a 3 month application of a canola phenolic acid-based cream (CPA) on AK lesions.

Patients and methods

This was a randomized, double-blind, placebo-controlled, 12 week clinical study conducted at a single-center in Santo Domingo, Dominican Republic. Forty-five subjects (30 CPA and 15 placebo), aged 45–85 years with 3–10 AKs within a 20 cm² treatment area (scalp, forehead, dorsal forearm, neck, or back of hand) were enrolled. The primary outcome was complete or partial lesion clearance and the secondary outcome was safety of CPA.

Results

Although complete AK lesion clearance was not seen in this study, a significant reduction in the mean change from baseline in the average lesion area was observed at weeks 3 (P=0.002), 6 (P<0.001), and 12 (P<0.001) in the CPA group, but only at weeks 6 and 12 in the placebo group (P=0.005 and P=0.002, respectively). Furthermore, the proportion of participants with a $10% decrease in average lesion area was significantly higher in the CPA group than the placebo group at weeks 3 (P=0.05) and 6 (P=0.02), and showed a trend at week 12 (P=0.06). A subset analysis of the change in average lesion area based upon the total lesion area at baseline revealed that CPA elicited a greater reduction than placebo (2×) in participants with a baseline total AK lesion area of 100–500 mm² than in participants with a total area <100 mm² (1.3×).

Conclusion

The results of this study and previous in vitro studies suggest a potential role for CPA in the treatment of AK lesions and the prevention of SCC development.

No chemopreventive effect of nonsteroidal anti-inflammatory drugs on nonmelanoma skin cancer: evidence from meta-analysis

Background

Nonmelanoma skin cancer (NMSC),which includes squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), is the most common form of cancer, and its incidence is increasing. Nonsteroidal anti-inflammatory drugs (NSAIDs) have been reported to be chemopreventive for NMSC. However, the results from published studies were controversial.

Methods

We searched the PubMed and Embase databases for relevant studies. Moreover, relevant reviews regarding the use of NSAIDs for NMSC patients were examined for potential inclusive studies. To measure the effects of NSAIDs, the relative risk (RR) was analyzed.

Results

A Total of 8 studies were included in our meta-analysis. We found that NSAIDs use was not associated with a reduced risk of SCC or BCC under the random effects model (pooled RR  =  0.86, 95% CI, 0.73–1.02, P  =  0.085; pooled RR  =  0.94, 95% CI 0.85–1.04, P  =  0.266; respectively).

Conclusion

From the included studies, we found no statistically significant chemopreventive effect on NMSC of NSAIDs. This finding warrants more prospective studies evaluating the relationship between NSAIDs and NMSC.

Photoprotective effects of apple peel nanoparticles

Plants contain enriched bioactive molecules that can protect against skin diseases. Bioactive molecules become unstable and ineffective due to unfavorable conditions. In the present study, to improve the therapeutic efficacy of phytodrugs and enhance photoprotective capability, we used poly(D,L-lactide-co-glycolide) as a carrier of apple peel ethanolic extract (APETE) on permeation-enhanced nanoparticles (nano-APETE). The in vitro toxicity of nano-APETE-treated dermal fibroblast cells were studied in a bioimpedance system, and the results coincided with the viability assay. In addition, the continuous real-time evaluations of photodamage and photoprotective effect of nano-APETE on cells were studied. Among three different preparations of nano-APETE, the lowest concentration provided small, spherical, monodispersed, uniform particles which show high encapsulation, enhanced uptake, effective scavenging, and sustained intracellular delivery. Also, the nano-APETE is more flexible, allowing it to permeate through skin lipid membrane and release the drug in a sustained manner, thus confirming its ability as a sustained transdermal delivery. In summary, 50 μM nano-APETE shows strong synergistic photoprotective effects, thus demonstrating its higher activity on target sites for the treatment of skin damage, and would be of broad interest in the field of skin therapeutics.

Topical treatment with diclofenac, calcipotriol (vitamin-D3 analog) and difluoromethylornithine (DFMO) does not prevent nonmelanoma skin cancer in mice

Nonmelanoma skin cancer is a common cancer type with increasing incidence. The purpose of this study was to evaluate topical application of diclofenac, calcipotriol, and difluoromethylornithine as chemoprevention in a mouse model of ultraviolet light-induced skin tumors, since these agents have been reported to have tumor inhibiting properties. One hundred twenty eight mice were treated with UVB radiation followed by chemoprevention or placebo. There were no significant effects of the treatments with respect to presence of skin tumors, number of tumors, tumor size, or survival. The investigated drugs were ineffective as chemoprevention in the dose regimens used in this study.

Pharmacotherapy of actinic keratosis: an update

INTRODUCTION

Actinic keratosis (AK) represents the initial intraepidermal manifestation of abnormal keratinocyte proliferation, with the potential of progression to squamous cell carcinoma (SCC). Few visible AKs lead to the use of lesion-directed treatments, including ablative and/or surgical procedures. Multiple and/or the suspicion of subclinical (non-visible) AKs lead to the use of field-directed therapies, including topical and ablative treatments. Predicting which AK will progress to SCC is difficult, and so all are treated. The goals of treatment are to eliminate visible AKs and to treat subclinical (non-visible) AKs, minimizing their risk of progression to invasive SCC, while pursuing good cosmesis.

AREAS COVERED

This review discusses the prevention of AKs (such as ultraviolet light avoidance, sunscreen use, protective clothing, and frequent self-examinations, in addition to chemoprevention with retinoids, eflornithine, silymarin, and others). It also covers lesion-directed treatments (e.g., cryotherapy, electrodessication and curettage, and surgery). Field-directed treatments are also mentioned (including laser resurfacing, dermabrasion, chemical peels, topical immunomodulators (imiquimod and diclofenac), topical chemotherapeutic agents (5-fluorouracil and retinoids), and photodynamic therapy). Finally, newer and investigational treatments are discussed (including ingenol mebutate).

EXPERT OPINION

There is no panacea in the treatment of AKs. The current best approach is the sequential treatment with a lesion-directed and a field-directed therapy. Several combinations seem to work well; they just need to be selected based on the evidence and adjusted to patient needs, preferences and dermatologist expertise.

Oxidative stress and skin cancer: an overview

Skin is the largest body organ that serves as an important environmental interface providing a protective envelope that is crucial for homeostasis. On the other hand, it is a major target for toxic insult by a broad spectrum of physical and chemical agents that are capable of altering its structure and function. There are a large number of dietary contaminants and drugs can manifest their toxicity in skin. These environmental toxicants or their metabolites are inherent oxidants and/or directly or indirectly drive the production of a variety of reactive oxidants also known as reactive oxygen species. These are short-lived entities that are continuously generated at low levels during the course of normal aerobic metabolism. These are believed to activate proliferative and cell survival signaling that can alter apoptotic pathways that may be involved in the pathogenesis of a number of skin disorders. The skin possesses an array of antioxidant defense mechanisms that interact with toxicants to obviate their deleterious effect. The "antioxidant power" of a food is an expression of its capability both to defend the human organism from the action of the free radicals and to prevent degenerative disorders. Plants like olive trees have their own built-in protection against the oxidative damage of the sun, and these built-in protectors function as cell protectors in our own body. Although many antioxidants have shown substantive efficacy in cell culture systems and in animal models of oxidant injury, unequivocal confirmation of their beneficial effects in human populations has proven elusive.

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.

Activation of p38 MAP kinase and JNK pathways by UVA irradiation

There are more than two million new cases of non-melanoma skin cancers (NMSCs) diagnosed each year in the United States of America. The clear etiological factor is chronic exposure to solar radiation from the sun. The wavelengths of solar light that reach the earth's surface include UVB (280-320 nm), which accounts for 1-10%, and UVA (320-400 nm), which accounts for 90-99% of the radiation. While most published research has focused on the effects of UVB, little is known concerning UVA-mediated signal transduction pathways, and their role in skin tumor promotion and progression, giving rise to squamous cell carcinomas (SCCs). Here, we focus on UVA-mediated activation of p38 MAP kinase and c-Jun N-terminal kinase (JNK), and their roles in activator protein-1 (AP-1) mediated transcription, cyclooxygenase-2 (COX-2) and Bcl-XL expression. Since p38 MAP kinase and JNK play major roles in the expression of UVA-induced AP-1, COX-2 and Bcl-XL, pharmacological inhibitors of these kinases may be useful in the chemoprevention of SCC skin cancer.

Melanoma chemoprevention in skin reconstructs and mouse xenografts using isoselenocyanate-4

Melanoma incidence and mortality rates continue to increase despite the use of sunscreen as well as screening programs for early surgical excision of premalignant lesions. The steady increase in melanoma incidence suggests that additional preventive approaches are needed to augment these existing strategies. One unexplored area involves targeting genes whose deregulation promotes disease development to prevent melanoma. The Akt3 signaling pathway is one key signaling cascade that plays a central role by deregulating apoptosis to promote development of approximately 70% of melanomas. Isoselenocyanate-4 (ISC-4), derived from isothiocyanates by increasing the alkyl chain length and replacing sulfur with selenium, has been developed to target this important signaling pathway in melanomas; however, its chemopreventive potential is unknown. In this study, the chemopreventive efficacy of topical ISC-4 was evaluated in a laboratory-generated human skin melanoma model containing early melanocytic lesion or advanced stage melanoma cell lines and in animals containing invasive xenografted human melanoma. Repeated topical application of ISC-4 reduced tumor cell expansion in the skin model by 80% to 90% and decreased tumor development in animals by approximately 80%. Histologic examination of ISC-4-treated skin showed no obvious damage to skin cells or skin morphology, and treated animals did not exhibit markers indicative of major organ-related toxicity. Mechanistically, ISC-4 prevented melanoma by decreasing Akt3 signaling that lead to a 3-fold increase in apoptosis rates. Thus, topical ISC-4 can delay or slow down melanocytic lesion or melanoma development in preclinical models and could impact melanoma incidence rates if similar results are observed in humans.

Polyhydroxylated fatty alcohols derived from avocado suppress inflammatory response and provide non-sunscreen protection against UV-induced damage in skin cells

Exposing skin to ultraviolet (UV) radiation contributes to photoaging and to the development of skin cancer by DNA lesions and triggering inflammatory and other harmful cellular cascades. The present study tested the ability of unique lipid molecules, polyhydroxylated fatty alcohols (PFA), extracted from avocado, to reduce UVB-induced damage and inflammation in skin. Introducing PFA to keratinocytes prior to their exposure to UVB exerted a protective effect, increasing cell viability, decreasing the secretion of IL-6 and PGE(2), and enhancing DNA repair. In human skin explants, treating with PFA reduced significantly UV-induced cellular damage. These results support the idea that PFA can play an important role as a photo-protective agent in UV-induced skin damage.

White oral lesions, actinic cheilitis, and leukoplakia: confusions in terminology and definition: facts and controversies

Many diseases affecting the cutaneous tissues may incur observable changes to the mucosal tissues of the oral cavity. As a consequence, the dermatologist should always assess the oral mucosal tissues of their patients as a matter of routine. Equivocal lesions should be referred to a dentist for further assessment. Although most encountered white oral lesions are innocuous, some potentially serious conditions may mimic an innocuous white lesion. As examples, oral lichen planus may cause significant patient discomfort and is associated with some degree of increased malignant risk, whereas actinic cheilitis and leukoplakia have a confirmed association with an increased malignant risk. This contribution reviews the characteristics and management strategies for some of the more common white oral lesions that the dermatologist may observe in clinical practice.