Epidermal hyperplasia overlying human melanoma correlates with tumour depth and angiogenesis

Contribution of Keratinocytes in Skin Cancer Initiation and Progression

Keratinocytes are major cellular components of the skin and are strongly involved in its homeostasis. Oncogenic events, starting mainly from excessive sun exposure, lead to the dysregulation of their proliferation and differentiation programs and promote the initiation and progression of non-melanoma skin cancers (NMSCs). Primary melanomas, which originate from melanocytes, initiate and develop in close interaction with keratinocytes, whose role in melanoma initiation, progression, and immune escape is currently being explored. Recent studies highlighted, in particular, unexpected modes of communication between melanocytic cells and keratinocytes, which may be of interest as sources of new biomarkers in melanomagenesis or potential therapeutic targets. This review aims at reporting the various contributions of keratinocytes in skin basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), and melanoma, with a greater focus on the latter in order to highlight some recent breakthrough findings. The readers are referred to recent reviews when contextual information is needed.

Clinical and Onychoscopic Features of Benign and Malignant Conditions in Longitudinal Melanonychia in the Thai Population: A Comparative Analysis

Background

Longitudinal melanonychia can arise from many underlying conditions, both benign and malignant. Practitioners tend to be reluctant to perform a biopsy of this condition due to procedure-related pain and the possibility of permanent nail dystrophy. Onychoscopy has become a useful tool to provide a provisional diagnosis and assist in deciding on a nail biopsy.

Objective

To investigate and differentiate the clinical and onychoscopic features of subungual melanoma (SUM)/subungual melanoma in situ (SMIS) and other benign melanocytic conditions (BM).

Materials and Methods

In this cross-sectional study, a total of 32 cases of longitudinal melanonychia were examined, and baseline characteristics were recorded. Onychoscopic pictures were taken by handheld dermoscopy with 10x and 50x magnification. A biopsy was then performed in each case, and a pathological diagnosis was obtained.

Results

Of the 32 cases, 6 were diagnosed with SMIS and 26 with BM (21 simple lentigines, 5 junctional nevi). The median age was significantly higher among the SMIS group (56 vs 31 years) (p = 0.034). Regarding onychoscopic findings, cases with SMIS were significantly associated with a greater band width percentage (p = 0.014), multicolor presentation (p = 0.005), the presence of granular pigmentation (p = 0.034), and micro-Hutchinson’s sign (p = 0.015). In addition, subungual hyperkeratosis, a newly recognized onychoscopic feature, was more significantly associated with SMIS in comparison to BM (p = 0.002).

Conclusion

Onychoscopy provides useful information to aid in the differential diagnosis of longitudinal melanonychia. From our study, onychoscopy can be utilized to assist in making a decision whether to perform a biopsy in patients with longitudinal melanonychia suspicious of malignant melanocytic conditions.

Amelanotic Lentigo Maligna Melanoma: Mohs Surgery as the Definitive Treatment of an Invisible Tumour

Amelanotic lentigo maligna melanoma represents <2% of melanomas. Diagnosis is delayed owing to the lack of lesion pigmentation and advanced disease at presentation. Excision with appropriate margins is the treatment standard, but the starting point for such margins is often unclear. We describe 2 patients with amelanotic melanoma treated by Mohs micrographic surgery (MMS) that would not have been cleared by wide local excision alone and provide an extensive review of the literature. Both patients presented with histologic diagnoses of malignant melanoma, one with a barely perceptible biopsy site scar on the left infraorbital cheek/lower eyelid (Breslow 1.8 mm) and the second with an amelanotic tumour on the right helix (Breslow 10 mm). Due to location, aggressive histology, amelanotic appearance, and no apparent surrounding skin surface changes, MMS was elected to maximise margin control. For patient 1, invasive and in situ tumour was found at the American Joint Committee on Cancer–recommended margin of 1.5 cm, and the final defect measured 8.5 × 4.8 cm. Patient 2 had a significant invasive and amelanotic lentigo maligna component, resulting in a 9.0 × 6.5-cm defect. MMS allows for immediate histologic feedback on tumour margins of a clinically invisible tumour and thus offers the most definitive treatment.

Intercellular crosstalk in human malignant melanoma

Incidence of malignant melanoma is increasing globally. While the initial stages of tumors can be easily treated by a simple surgery, the therapy of advanced stages is rather limited. Melanoma cells spread rapidly through the body of a patient to form multiple metastases. Consequently, the survival rate is poor. Therefore, emphasis in melanoma research is given on early diagnosis and development of novel and more potent therapeutic options. The malignant melanoma is arising from melanocytes, cells protecting mitotically active keratinocytes against damage caused by UV light irradiation. The melanocytes originate in the neural crest and consequently migrate to the epidermis. The relationship between the melanoma cells, the melanocytes, and neural crest stem cells manifests when the melanoma cells are implanted to an early embryo: they use similar migratory routes as the normal neural crest cells. Moreover, malignant potential of these melanoma cells is overdriven in this experimental model, probably due to microenvironmental reprogramming. This observation demonstrates the crucial role of the microenvironment in melanoma biology. Indeed, malignant tumors in general represent complex ecosystems, where multiple cell types influence the growth of genetically mutated cancer cells. This concept is directly applicable to the malignant melanoma. Our review article focuses on possible strategies to modify the intercellular crosstalk in melanoma that can be employed for therapeutic purposes.

Melanoma cells influence the differentiation pattern of human epidermal keratinocytes

Background

Nodular melanoma is one of the most life threatening tumors with still poor therapeutic outcome. Similarly to other tumors, permissive microenvironment is essential for melanoma progression. Features of this microenvironment are arising from molecular crosstalk between the melanoma cells (MC) and the surrounding cell populations in the context of skin tissue. Here, we study the effect of melanoma cells on human primary keratinocytes (HPK). Presence of MC is as an important modulator of the tumor microenvironment and we compare it to the effect of nonmalignant lowly differentiated cells also originating from neural crest (NCSC).

Methods

Comparative morphometrical and immunohistochemical analysis of epidermis surrounding nodular melanoma (n = 100) was performed. Data were compared to results of transcriptome profiling of in vitro models, in which HPK were co-cultured with MC, normal human melanocytes, and NCSC, respectively. Differentially expressed candidate genes were verified by RT-qPCR. Biological activity of candidate proteins was assessed on cultured HPK.

Results

Epidermis surrounding nodular melanoma exhibits hyperplastic features in 90% of cases. This hyperplastic region exhibits aberrant suprabasal expression of keratin 14 accompanied by loss of keratin 10. We observe that MC and NCSC are able to increase expression of keratins 8, 14, 19, and vimentin in the co-cultured HPK. This in vitro finding partially correlates with pseudoepitheliomatous hyperplasia observed in melanoma biopsies. We provide evidence of FGF-2, CXCL-1, IL-8, and VEGF-A participation in the activity of melanoma cells on keratinocytes.

Conclusion

We conclude that the MC are able to influence locally the differentiation pattern of keratinocytes in vivo as well as in vitro. This interaction further highlights the role of intercellular interactions in melanoma. The reciprocal role of activated keratinocytes on biology of melanoma cells shall be verified in the future.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-14-1) contains supplementary material, which is available to authorized users.

Melanoma's connections to the tumour microenvironment

SUMMARY

Melanoma cells interact with and depend on seemingly normal cells in their tumour microenvironment to allow the acquisition of the hallmarks of solid cancer. In general, there are three types of interaction of melanoma cells with their microenvironment. First, there is bilateral communication between melanoma cells and the stroma, which includes fibroblasts, endothelial cells, immune cells, soluble molecules, and the extracellular matrix. Second, while under normal conditions keratinocytes control localisation and proliferative behaviour of melanocytes in the epidermis, once this balance is disturbed and a melanoma has developed, melanoma cells may take over the control of their epidermal tumour microenvironment. Finally, there are subcompartments within tumours with different microenvironmental milieu defined by their access to oxygen and nutrients. Therefore, different melanoma cells within a tumour face different microenvironments. Interactions between melanoma cells among each other and with the cell types in their microenvironment happen through endocrine and paracrine communication and/or through direct contact via cell-cell and cell-matrix adhesion, and gap junctional intercellular communication (GJIC). Connexins have been identified as key molecules for direct cell-cell communication and are also thought to be important for the release of signalling molecules from cells to the microenvironment. In this review we provide an update of the alterations in cell-cell communication in melanoma and the tumour microenvironment associated with melanoma development and progression.

Gene regulatory and clinical effects of interferon β in patients with metastatic melanoma: a phase II trial

Interferon (IFN)-β in preclinical studies, compared to IFN-α2, bound with higher affinity to its receptor, induced to higher levels of IFN-stimulated gene products, induced more apoptosis in melanoma cells, and had antitumor effects against melanoma. A maximally tolerated dose of 12 × 10(6) international units/m(2) after 2 weeks subcutaneously daily with dose escalation to 18 × 10(6) international units/m(2) was thus used in a phase II trial of IFN-β1a in cutaneous metastatic melanoma (n = 17) and uveal melanoma (n = 4). It resulted in expected but reversible drug-related severe (grade 3) adverse events in 13/21 patients; anorexia and fatigue were mostly of mild or moderate severity and infrequently needed dose reduction. Although a single patient had a sustained regression, overall IFN-β1a did not have clinical benefit (response rate <10%; median progression-free survival 1.8 months). Effective and potent induction in peripheral blood cells and into serum of products of IFN-stimulated genes such as the pro-apoptotic cytokine, TRAIL, and the immunomodulatory and anti-angiogenic chemokines, CXCL10 and CCL8, confirmed gene regulatory actions. To probe further anti-angiogenic mechanisms, both VEGF-A and CXCL-5 were assessed; compared to before treatment, both proteins decreased. Continued improvements in understanding of antitumor mechanisms will enhance usefulness of IFNs for nodal or distant metastases from melanoma.

Melanoma progression exhibits a significant impact on connexin expression patterns in the epidermal tumor microenvironment

Melanoma depends on, interacts with and reacts to the stroma in which it is embedded, including fibroblasts, extracellular matrix, endothelial cells and immune cells. However, the impact of melanoma on the epidermal tumor microenvironment-the multilayered epithelium of the skin-is poorly understood. Gap junctions are essential for intercellular communication and involved in proliferation, differentiation and homeostasis of keratinocytes. We have shown previously that the gap junction proteins connexin 26 and 30 (Cx26 and Cx30) are induced in the epidermal tumor microenvironment of skin cancers including melanoma. This study compares the extent of Cx26, Cx30 and Cx43 expression in the epidermal microenvironment of melanocytic nevi and melanomas and its association with melanoma thickness, proliferative index of the tumor and its microenvironment, and with 5-year metastasis and survival. We found that induction of Cx26 and Cx30 cell-cell border expression in the epidermal tumor microenvironment correlates to malignancy. Importantly, there was a significant correlation of tumor thickness with the vertical epidermal Cx26 and Cx30 expression pattern and the horizontal Cx26 dissemination. Furthermore, horizontal Cx26 expression correlated with metastasis. Vertical epidermal expression patterns of Cx26 and Cx30 significantly correlated with the proliferative index in the epidermal tumor microenvironment but not with the proliferative index in the tumor. In contrast, Cx43 did not correlate with malignancy, thickness or proliferative index. In summary, here we show for the first time a significant association between the progression of melanoma and alterations in its epithelial tumor microenvironment.

The disintegrin-metalloproteinases ADAM 10, 12 and 17 are upregulated in invading peripheral tumor cells of basal cell carcinomas

BACKGROUND

Members of the a disintegrin and metalloproteinase (ADAM) family are expressed in malignant tumors and participate in the pathogenesis of cancer. However, the presence of ADAM 10, 12, 17 and their role in basal cell carcinoma (BCC) have not been described. The purpose of this study was to investigate expression of ADAM 10, 12 and 17 in BCC.

METHODS

Expression of ADAM 10, 12 and 17 was analyzed by immunohistochemistry in skin tissues obtained from 25 patients with different types of BCC.

RESULTS

Immunoreactivity of ADAM 10, 12 and 17 was increased at the peripheral tumor margin compared with central areas of BCC tumor cell nests. Immunoreactivity of ADAM 10 and 12 was increased in the deep margin of invading tumor cell nests in mixed BCC. Focally increased expression of ADAM 12 was detected in squamous differentiated tumor cells of nodular BCC. In addition, immunoreactivity of ADAM 17 was increased in superficial BCC.

CONCLUSIONS

ADAM 10, 12 and 17 showed different expression pattern in BCC histologic subtypes, indicating their different role in the BCC pathogenesis. Overexpression of ADAM 10, 12 and 17 immunoreactivity in deep invasion area of BCC indicates that these three proteases may play an important role in the locally invasive and highly destructive growth behavior of BCC. Additionally, we suggest that ADAM 17 may play an important role in early development of BCC.

Phase II trial of pegylated interferon and thalidomide in malignant metastatic melanoma

Pegylated interferon and thalidomide demonstrate immunomodulatory and antiangiogenic activity, and efficacy in melanoma. The combination was evaluated in a phase II trial. Eligibility included biopsy-confirmed malignant melanoma with metastases and progression, maximum of two earlier systemic therapies, performance status of 0-2, and adequate hepatic, bone marrow and renal function. Pegylated interferon was administered at a dose of 0.5 microg/kg subcutaneously weekly and thalidomide 200 mg orally daily. Toxicity was evaluated every 2 weeks and response every 8 weeks. Eighteen patients were enrolled in this trial. Median age was 55.5 years (range: 29-80 years). Seventeen patients had visceral metastases and one had lymph node-only metastases. Two patients had brain metastases. Nine patients had received earlier adjuvant therapy and 16 patients had received earlier therapy for metastatic disease. Performance status was 0, 1 and 2 in 11, six and one patients, respectively. Severe (grade 4) toxicities observed were anemia in two patients and thrombocytopenia in one patient. No treatment-related deaths occurred. Dose escalation of thalidomide to 300 mg daily was feasible in four patients. One therapy-related hospitalization for nausea and dehydration occurred. No objective responses were noted; three patients demonstrated disease stabilization. The regimen of pegylated interferon and thalidomide was well tolerated. The combination, however, failed to demonstrate clinical efficacy in pretreated metastatic malignant melanoma.

Unusual occurrence of a melanoma with intermixed epithelial component: a true melanocarcinoma?: case report and review of epithelial differentiation in melanoma by light microscopy and immunohistochemistry

We report a case of a 27-year-old woman with a nonpigmented lesion on the right scalp. Histological examination showed a malignant nodular neoplasm with 2 distinct but intimately admixed components: a malignant melanoma with a spindle component and an unusual glandular component. Immunohistochemical studies demonstrated epithelial differentiation on the basis of cytokeratin (CAM5.2 and AE1/AE3) expression in the glandular component and melanocytic differentiation (HMB-45, PNL2, MITF, and S-100) of the spindle cell component. A single melanocytic marker (MITF) was expressed in both components, raising the possibility of dual differentiation in a single tumor, rather than the alternative considerations of a collision tumor or a reactive pseudoepitheliomatous hyperplasia with eccrine duct lumen formation within a melanoma. This unusual tumor with both melanocytic and epithelial components may represent a true melanocarcinoma, which becomes a plausible consideration, in view of melanoma plasticity and recent experimental evidence and speculation about the role of stem cells in melanoma.

Targeting endothelial and tumor cells with semaphorins

Neuropilins (NRP) are receptors for the class 3 semaphorin (SEMA3) family of axon guidance molecules and the vascular endothelial growth factor (VEGF) family of angiogenesis factors. Although the seminal studies on SEMA3s and NRPs first showed them to be mediators of axon guidance, it has become very apparent that these proteins play an important role in vascular and tumor biology as well. Neuronal guidance and angiogenesis are regulated similarly at the molecular level. For example, SEMA3s not only repel neurons and collapse axon growth cones, but have similar effects on endothelial cells and tumor cells. Preclinical studies indicate that SEMA3F is a potent inhibitor of tumor angiogenesis and metastasis. In addition, neutralizing antibodies to NRP1 enhance the effects of anti-VEGF antibodies in suppressing tumor growth in xenograft models. This article reviews NRP and SEMA3 structural interactions and their role in developmental angiogenesis, tumor angiogenesis and metastasis based on cell culture, zebrafish and murine studies.

Differential growth of IFN-beta-engineered tumor cells in nude and IFN receptor-null mice

The purpose of this study was to investigate the therapeutic potential of interferon-beta (IFN-beta) against tumors that resist its antiproliferative effects. Mouse fibrosarcoma cells (UV-2237m-P) and their counterparts, transfected with either IFN-beta cDNA (UV-2237m-IFN-beta) or its control vector (UV-2237m-neo), were used in the study. UV-2237m-IFN-beta cells, still expressing functional IFN receptors, were resistant to the antiproliferative effects of IFN-beta. UV-2237m-P and UV-2237m-neo cells produced progressive tumors in both nude and IFN receptor-null nude (IFNAR-/-nude) mice. In contrast, growth of UV-2237m-IFN-beta cells was significantly delayed in nude mice. UV-2237m-IFN-beta tumors from nude mice contained fewer microvessels, fewer proliferating cells, and more apoptotic cells than did UV-2237m-P and UV-2237m-neo tumors. They expressed high levels of inducible nitric oxide synthase (iNOS) and were densely infiltrated by macrophages. Incubation with macrophages from nude mice, but not those from IFNAR-/- nude mice or iNOS-null/nude mice, led to more significant killing of UV-2237m-IFN-beta cells than that of control cells, which was blocked by iNOS inhibitor N-methylarginine. Similarly, more UV-2237m-IFN-beta cells were killed when they were incubated with spleen lymphocytes from nude mice. These data indicate that IFN-beta can inhibit growth of IFN-beta-resistant tumors by T cell-independent host-mediated mechanisms, including the role of macrophages, natural killer (NK) cells, and iNOS activity.

Distinct phenotypic changes between the superficial and deep component of giant congenital melanocytic naevi: a rationale for curettage

BACKGROUND

Giant congenital melanocytic naevi (GCMN) convey a 14-fold increased melanoma risk. In contrast, medium congenital melanocytic naevi (MCMN) are rarely associated with malignant transformation. Management of patients with GCMN is challenging and there is no consensus on the most appropriate strategy for treating these patients.

OBJECTIVES

To provide a rationale for performing curettage of GCMN in the neonatal period in order to reduce the risk of malignant transformation to melanoma.

METHODS

Twenty-six infants with GCMN who underwent biopsies before excisional surgery (n = 7) or curettage (n = 19) during the past 14 years (Academic Hospital, Vrije Universiteit Brussel) and 10 MCMN patients who underwent excision biopsies (Radboud University Nijmegen Medical Centre) were included in this study. Using these biopsies, we performed genetic and detailed immunohistochemical evaluations of changes that are associated with malignant transformation. Variables of interest included melanoma-associated BRAF mutations, proliferative activity, vascularity, cellular context and extracellular matrix architecture.

RESULTS

GCMN and MCMN did not show oncogenic BRAF mutation and displayed similar features with respect to the amount of nonmelanocytic cells within the naevus and matrix architecture. Naevus cells in the superficial component of the GCMN, however, were more proliferative, and this component was more vascular compared with its deep component and with MCMN. In this study, none of the 19 newborn patients who underwent curettage developed a melanoma within a mean follow-up time of 7 years.

CONCLUSIONS

The data presented here support the idea that curettage of GCMN in neonates has the potential for lowering the risk of developing cutaneous melanoma by not only obtaining an important numerical reduction of naevus cells but also removing the 'active' melanocytes.

Semaphorin 3F, a chemorepulsant for endothelial cells, induces a poorly vascularized, encapsulated, nonmetastatic tumor phenotype

Melanoma is the most lethal skin cancer. Most deaths from melanoma result from metastases. Semaphorins have been shown to inhibit neuronal and endothelial cell migration, but the effects of semaphorins on tumor metastasis have not been documented. We found that semaphorin 3F (SEMA3F) was markedly downregulated in highly metastatic human cell lines in vitro and in vivo, which suggested that it may be a metastasis inhibitor. Metastatic human melanoma cells were transfected with SEMA3F and implanted into mice; the resultant tumors did not metastasize. Rather, the primary tumors resembled benign nevi characterized by large areas of apoptosis, diminished vascularity, inhibition of hyperplasia in overlying epidermal cells, and encapsulated tumor borders delineated by thick layers of fibroblasts and collagen matrix. This phenotype is in stark contrast to highly invasive, vascular mock-transfected tumors. In vitro, tumor cells expressing SEMA3F had a diminished capacity to adhere and migrate on fibronectin. Consistent with semaphorin-mediated chemorepulsion of neurons, tumor cells expressing SEMA3F were chemorepulsive for vascular and lymphatic endothelial cells expressing neuropilin-2 (NRP2), a novel mechanism for a tumor angiogenesis inhibitor. The repulsive activity was abrogated by NRP2 RNA interference. Together these results indicate that SEMA3F is a potent metastasis inhibitor that targets both tumor and stromal cells and raise the possibility of SEMA3F having therapeutic potential.

Angiopoietin-related growth factor (AGF) promotes angiogenesis

We report here the identification of angiopoietin-related growth factor (AGF) as a positive mediator for angiogenesis. To investigate the biologic function of AGF in angiogenesis, we analyzed the vasculature in the dermis of transgenic mice expressing AGF in mouse epidermal keratinocytes (K14-AGF). K14-AGF transgenic mice were grossly red, especially in the ears and snout, suggesting that hypervascularization had occurred in their skin. Histologic examination of ear skin from K14-AGF transgenic mice revealed increased numbers of microvessels in the dermis, whereas the expression of several angiogenic factors, such as basic fibroblast growth factor (bFGF), vascular endothelial growth factors (VEGFs), and angiopoietin-1 (Ang-1), was decreased. We showed that AGF is a secreted protein and does not bind to tyrosine kinase with immunoglobulin and EGF-homology domain (Tie1) or Tie2 receptors. An in vitro chamber assay revealed that AGF directly promotes chemotactic activity of vascular endothelial cells. Both mouse corneal and matrigel plug assays showed that AGF induces neovascularization in vivo. Furthermore, we found that plasma leakage occurred after direct injection of AGF into the mouse dermis, suggesting that AGF directly induces a permeability change in the local vasculature. On the basis of these observations, we propose that AGF is a novel angiogenic factor and that handling of its biologic functions could lead to novel therapeutic strategies for control of angiogenesis.