Topical application of dimethylbenz[a]anthracene results in the generation of multiple melanocytic nevi in C3H/HeN mice

Nanotechnology Addressing Cutaneous Melanoma: The Italian Landscape

Cutaneous melanoma is one of the most aggressive solid tumors, with a low survival for the metastatic stage. Currently, clinical melanoma treatments include surgery, chemotherapy, targeted therapy, immunotherapy and radiotherapy. Of note, innovative therapeutic regimens concern the administration of multitarget drugs in tandem, in order to improve therapeutic efficacy. However, also, if this drug combination is clinically relevant, the patient's response is not yet optimal. In this scenario, nanotechnology-based delivery systems can play a crucial role in the clinical treatment of advanced melanoma. In fact, their nano-features enable targeted drug delivery at a cellular level by overcoming biological barriers. Various nanomedicines have been proposed for the treatment of cutaneous melanoma, and a relevant number of them are undergoing clinical trials. In Italy, researchers are focusing on the pharmaceutical development of nanoformulations for malignant melanoma therapy. The present review reports an overview of the main melanoma-addressed nanomedicines currently under study in Italy, alongside the state of the art of melanoma therapy. Moreover, the latest Italian advances concerning the pre-clinical evaluation of nanomedicines for melanoma are described.

Analysis of major elements in pigmented melanocytic chicken skin using laser-induced breakdown spectroscopy

The concentration difference of major elements in melanocytic skin with respect to pigmentation level is analysed by laser-induced breakdown spectroscopy (LIBS) to investigate the applicability of LIBS as an in situ feedback tool for selective and complete laser removal of melanocytic skin tissue like nevus. The skin of black silkie chicken which had a characteristic darkly pigmented perifollicular skin surrounded by lightly pigmented extrafollicular skin was used as the sample. The results showed higher LIBS signal intensities of Ca²⁺ and Mg²⁺ but lower intensities of Na⁺ , Cl^- and K⁺ in the perifollicular skin than in the extrafollicular skin, which demonstrated the feasibility to use LIBS as a reliable method to distinguish skin tissues with difference in pigmentation level. Plasma emission of biochemical elements generated with a laser irradiation on melanocytic skin lesion.

A murine model for the development of melanocytic nevi and their progression to melanoma

Acquired melanocytic nevi are commonly found in sun exposed and unexposed human skin, but the potential for their transformation into invasive melanoma is not clear. Therefore, a mouse model of nevus initiation and progression was developed in C3H/HeN mice using a modified chemical carcinogenesis protocol. Nevi develop due to DNA damage initiated by dimethylbenz(a) anthracene (DMBA) followed by chronic promotion with 12‐O‐tetradecanoyl‐phorbol‐13‐acetate (TPA). Dysplastic pigmented skin lesions appeared in 7–9 wk with 100% penetrance. Nests of melanocytic cells appeared in a subset of skin draining lymph nodes (dLN) by 25 wk, but not in age matched controls. Immunohistochemistry, real‐time PCR, and flow cytometric analyses confirmed their melanocytic origin. Transformed cells were present in a subset of nevi and dLNs, which exhibited anchorage‐independent growth, tumor development, and metastasis in nude mice. Approximately 50% of the cell lines contained H‐Ras mutations and lost tumor suppressor p16^Ink4a expression. While most studies of melanoma focus on tumor progression in transgenic mouse models where the mutations are present from birth, our model permits investigation of acquired mutations at the earliest stages of nevus initiation and promotion of nevus cell transformation. This robust nevus/melanoma model may prove useful for identifying genetic loci associated with nevus formation, novel oncogenic pathways, tumor targets for immune‐prevention, screening therapeutics, and elucidating mechanisms of immune surveillance and immune evasion. © 2015 The Authors. Molecular Carcinogenesis, published by Wiley Periodicals, Inc.

MC1R, eumelanin and pheomelanin: their role in determining the susceptibility to skin cancer

Skin pigmentation is due to the accumulation of two types of melanin granules in the keratinocytes. Besides being the most potent blocker of ultraviolet radiation, the role of melanin in photoprotection is complex. This is because one type of melanin called eumelanin is UV absorbent, whereas the other, pheomelanin, is photounstable and may even promote carcinogenesis. Skin hyperpigmentation may be caused by stress or exposure to sunlight, which stimulates the release of α-melanocyte stimulating hormone (α-MSH) from damaged keratinocytes. Melanocortin 1 receptor (MC1R) is a key signaling molecule on melanocytes that responds to α-MSH by inducing expression of enzymes responsible for eumelanin synthesis. Persons with red hair have mutations in the MC1R causing its inactivation; this leads to a paucity of eumelanin production and makes red-heads more susceptible to skin cancer. Apart from its effects on melanin production, the α-MSH/MC1R signaling is also a potent anti-inflammatory pathway and has been shown to promote antimelanoma immunity. This review will focus on the role of MC1R in terms of its regulation of melanogenesis and influence on the immune system with respect to skin cancer susceptibility.

The dysplastic nevus: from historical perspective to management in the modern era: part I. Historical, histologic, and clinical aspects

Since its description in the 1970s, the dysplastic nevus has been a source of confusion, and whether it represents a precursor to melanoma remains a controversial subject. Although a Consensus Conference in 1992 recommended that the term "dysplastic nevus" no longer be used, the histologic diagnosis continues to present a therapeutic quandary for dermatologists and other physicians, and there remains significant variation in clinical management. In part I of this continuing medical education review, we will discuss the historical origins of the term, the evidence for its distinct histologic basis, and its clinical significance.

Animal models of melanoma: a somatic cell gene delivery mouse model allows rapid evaluation of genes implicated in human melanoma

The increasing incidence and mortality associated with advanced stages of melanoma are cause for concern. Few treatment options are available for advanced melanoma and the 5-year survival rate is less than 15%. Targeted therapies may revolutionize melanoma treatment by providing less toxic and more effective strategies. However, maximizing effectiveness requires further understanding of the molecular alterations that drive tumor formation, progression, and maintenance, as well as elucidating the mechanisms of resistance. Several different genetic alterations identified in human melanoma have been recapitulated in mice. This review outlines recent progress made in the development of mouse models of melanoma and summarizes what these findings reveal about the human disease. We begin with a discussion of traditional models and conclude with the recently developed RCAS/TVA somatic cell gene delivery mouse model of melanoma.

Melanocyte expression of survivin promotes development and metastasis of UV-induced melanoma in HGF-transgenic mice

We previously found the apoptosis inhibitor Survivin to be expressed in melanocytic nevi and melanoma but not in normal melanocytes. To investigate the role of Survivin in melanoma development and progression, we examined the consequences of forced Survivin expression in melanocytes in vivo. Transgenic (Tg) mouse lines (Dct-Survivin) were generated with melanocyte-specific expression of Survivin, and melanocytes grown from Dct-Survivin mice expressed Survivin. Dct-Survivin melanocytes exhibited decreased susceptibility to UV-induced apoptosis but no difference in proliferative capacity compared with melanocytes derived from non-Tg littermates. Induction of nevi in Dct-Survivin and non-Tg mice by topical application of 7,12-dimethylbenz(a)anthracene did not reveal significant differences in lesion onset (median, 10 weeks) or density (4 lesions per mouse after 15 weeks). Dct-Survivin mice were bred with melanoma-prone MH19/HGF-B6 Tg mice, and all progeny expressing either individual, neither, or both (Survivin/HGF) transgenes were UV-treated as neonates and then monitored for 43 weeks. Melanocytes in neonatal Survivin+/HGF+ mouse skin were less susceptible to UV-induced apoptosis than those from Survivin-/HGF+ mice. Onset of melanocytic tumors was earlier (median, 18 versus 24 weeks; P = 0.01, log-rank test), and overall tumor density was greater (7.7 versus 5.2 tumors per mouse; P = 0.04) in Survivin+/HGF+ compared with Survivin-/HGF+ mice. Strikingly, melanomas arising in Survivin+/HGF+ mice showed a greater tendency for lymph node (35% versus 0%; P = 0.04) and lung (53% versus 22%) metastasis and lower rates of spontaneous apoptosis than those in Survivin-/HGF+ mice. These studies show a role for Survivin in promoting both early and late events of UV-induced melanoma development in vivo.