Neoplastic progression and prognosis in melanoma

Differential Gene Expression and Methylation Analysis of Melanoma in TCGA Database to Further Study the Expression Pattern of KYNU in Melanoma

Background: The aim of this study was to analyze and compare melanoma gene expression profiles in TCGA database through the application of different genes to explore the pathogenesis of melanoma. Furthermore, we confirmed the extent of the role of KYNU in melanoma and whether it can be a potential target for the diagnosis and treatment of melanoma. Methods: The gene expression profiles of melanoma samples were downloaded from TCGA database, and matrix files were synthesized to screen differential genes. The Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway analysis and GCDA broad institute were used to analyze common gene locus mutations and expression changes in melanoma, as well as methylation. In addition, the expression patterns of KYNU in melanoma were quantified by immunohistochemistry, Western blotting, qRT-PCR, software such as GEO DataSets and the Human Protein Atlas, and meta-analysis of skin diseases. KYNU was overexpressed in keratinocytes (HaCaT and HEKα) and melanoma cells (A375 and H1205-lu). CFDA-SE, Annexin V–PI double staining, and PI single staining were used to investigate the mechanism of KYNU in melanoma and its effects on melanoma proliferation, apoptosis, invasion, and migration. Results: The main signaling pathways involved in melanoma were EGF/EGFR–RAS–BRAF–MEK–ERK–CyclinD1/CDK4, Ras–PI3K–PTEN–PKB/AKT, and p14/p16 (CDKN2A)–MDM2–p53–p21–cyclinD1/CDK4/6–Rb/E2F. Moreover, MITF, KIT, CDH1. NRAS, AKT1, EGFR, TP53, KIT, and CDK4 were elevated in melanoma, whereas PTEN, cAMP, and BCL2 were reduced in melanoma. The copy number of tumor-promoting genes increased, while the copy number of tumor suppressor genes decreased. Changes in the copy number of the above tumor genes enriched in chromosomes were found through SNP gene mutations. The genes whose expression was negatively regulated by DNA methylation in melanoma included KRT18, CDK2, JAK3, BCL2, MITF, MET, CXCL10, EGF, SOX10, SOCS3, and KIT. The mutation rate of KYNU was high according to TCGA database. The KYNU level was decreased in melanoma. Overexpression of KYNU can promote changes in apoptotic BCL-2, metabolic KYN, 3-HAA, invasion and migration MMP9, E-cadherin, and other related proteins in melanoma. Fluorescence staining and flow analysis showed that a slower proliferation rate led to a stronger fluorescence intensity. In melanoma tumor cells with a low expression of KYNU, overexpression of KYNU could promote tumor cell apoptosis. IL-10 induced immunoregulatory changes in melanoma. The expression of MMP9 and AMPK decreased in A375, but the change in BCL-2 was not obvious. The expression of BCL-2 decreased significantly in H1205-lu. A375 showed cell-cycle arrest, indicating that IL-10 could slow down the cell cycle of melanoma. Conclusions: These results provide insights into the pathologic mechanisms of melanoma target genes and KYNU as a biomarker and potential therapeutic factor for melanoma.

Machine Learning Analysis of Immune Cells for Diagnosis and Prognosis of Cutaneous Melanoma

Tumor infiltration, known to associate with various cancer initiations and progressions, is a promising therapeutic target for aggressive cutaneous melanoma. Then, the relative infiltration of 24 kinds of immune cells in melanoma was assessed by a single sample gene set enrichment analysis (ssGSEA) program from a public database. The multiple machine learning algorithms were applied to evaluate the efficiency of immune cells in diagnosing and predicting the prognosis of melanoma. In comparison with the expression of immune cell in tumor and normal control, we built the immune diagnostic models in training dataset, which can accurately classify melanoma patients from normal (LR AUC = 0.965, RF AUC = 0.99, SVM AUC = 0.963, LASSO AUC = 0.964, and NNET AUC = 0.989). These diagnostic models were also validated in three outside datasets and suggested over 90% AUC to distinguish melanomas from normal patients. Moreover, we also developed a robust immune cell biomarker that could estimate the prognosis of melanoma. This biomarker was also further validated in internal and external datasets. Following that, we created a nomogram with a composition of risk score and clinical parameters, which had high accuracies in predicting survival over three and five years. The nomogram's decision curve revealed a bigger net benefit than the tumor stage. Furthermore, a risk score system was used to categorize melanoma patients into high- and low-risk subgroups. The high-risk group has a significantly lower life expectancy than the low-risk subgroup. Finally, we observed that complement, epithelial-mesenchymal transition, and inflammatory response were significantly activated in the high-risk group. Therefore, the findings provide new insights for understanding the tumor infiltration relevant to clinical applications as a diagnostic or prognostic biomarker for melanoma.

Comprehensive analysis of cancer hallmarks in cutaneous melanoma and identification of a novel unfolded protein response as a prognostic signature

Molecular pathways regulating the initiation and development of melanoma are potential therapeutic targets for this aggressive skin cancer. Therefore, transcriptome profiles of cutaneous melanoma were obtained from a public database and used to systematically evaluate cancer hallmark pathways enriched in melanoma. Finally, the unfolded protein response pathway was screened out, and the unfolded protein response-related genes were used to develop a robust biomarker that can predict the prognosis of melanoma, especially for younger, metastatic and high Clark level patients. This biomarker was further validated in two other independent datasets. In addition, melanoma patients were divided into high- and low-risk subgroups by applying a risk score system. The high-risk group exhibited higher immune infiltration and higher expression of N6-methyladenosine RNA methylation regulators, and had significantly shorter survival times than the low-risk subgroup. Gene Set Enrichment Analysis revealed that, among the enriched genes, gene sets involved in immune response and the extracellular matrix receptor interaction were significantly activated in the high-risk group. Our findings thus provide a new clinical application for prognostic prediction as well as potential targets for treatment of melanoma.

Melanoma tumour vasculature heterogeneity: from mice models to human

Tumour angiogenesis is defined by an anarchic vasculature and irregularities in alignment of endothelial cells. These structural abnormalities could explain the variability in distribution of nanomedicines in various tumour models. Then, the main goal of this study was to compare and to characterize the tumour vascular structure in different mouse models of melanoma tumours (B16F10 and SK-Mel-28) and in human melanomas from different patients. Tumours were obtained by subcutaneous injection of 10⁶ B16F10 and 3.10⁶ SK-Mel-28 melanoma cells in C57BL/6 and nude mice, respectively. Tumour growth was evaluated weekly, while vasculature was analysed through fluorescent labelling via CD31 and desmin. Significant differences in tumour growth and mice survival were evidenced between the two melanoma models. A fast evolution of tumours was observed for B16F10 melanoma, reaching a tumour size of 100 mm³ in 7 days compared to SK-Mel-28 which needed 21 days to reach the same volumes. Important differences in vascularization were exposed between the melanoma models, characterized by a significant enhancement of vascular density and a significant lumen size for mice melanoma models compared to human. Immunostaining revealed irregularities in endothelium structure for both melanoma models, but structural differences of vasculature were observed, characterized by a stronger expression of desmin in SK-Mel-28 tumours. While human melanoma mainly develops capillaries, structural irregularities are also observed on the samples of this tumour model. Our study revealed an impact of cell type and tumour progression on the structural vasculature of melanoma, which could impact the distribution of drugs in the tumour environment.

Metastases of malignant neoplasms: Historical, biological, & clinical considerations

The metastasis of neoplastic cells from their site of origin to distant anatomic locations continues to be the principal cause of death from malignant tumors, and that fact has been recognized by physicians for over a century. After the work done by Halsted in the treatment of breast cancer in the 1880s, accepted surgical canon held that metastasis occurred in a linear fashion, with centrifugal "growth in continuity" from the primary neoplasm that first involved regional lymph nodes. Those structures were considered to then be the sources of more distant, visceral metastases. With that premise in mind, radical and "ultra-radical" surgical procedures were devised to remove as many lymph nodes as possible in the treatment of carcinomas and melanomas. However, such interventions were ineffective in altering tumor-related mortality. This review considers the details of the historical material just mentioned. It also reviews currently-held concepts on biological mechanisms of metastasis, the "sentinel" lymph node biopsy technique, and the important topic of metastatic tumor "dormancy" as the cause of surgical treatment failure. Finally, predictive models of tumor behavior are discussed, which are based on gene signatures. These will likely be the key to identifying malignant lesions of low surgical stage that ultimately prove fatal through later manifestation of metastasis.

Conservation of immune gene signatures in solid tumors and prognostic implications

Background

Tumor-infiltrating leukocytes can either limit cancer growth or facilitate its spread. Diagnostic strategies that comprehensively assess the functional complexity of tumor immune infiltrates could have wide-reaching clinical value. In previous work we identified distinct immune gene signatures in breast tumors that reflect the relative abundance of infiltrating immune cells and exhibited significant associations with patient outcomes. Here we hypothesized that immune gene signatures agnostic to tumor type can be identified by de novo discovery of gene clusters enriched for immunological functions and possessing internal correlation structure conserved across solid tumors from different anatomic sites.

Methods

We assembled microarray expression datasets encompassing 5,295 tumors of the breast, colon, lung, ovarian and prostate. Unsupervised clustering methods were used to determine number and composition of gene clusters within each dataset. Immune-enriched gene clusters (signatures) identified by gene ontology enrichment were analyzed for internal correlation structure and conservation across tumors then compared against expression profiles of: 1) flow-sorted leukocytes from peripheral blood and 2) >300 cancer cell lines from solid and hematologic cancers. Cox regression analysis was used to identify signatures with significant associations with clinical outcome.

Results

We identified nine distinct immune-enriched gene signatures conserved across all five tumor types. The signatures differentiated specific leukocyte lineages with moderate discernment overall, and naturally organized into six discrete groups indicative of admixed lineages. Moreover, seven of the signatures exhibit minimal and uncorrelated expression in cancer cell lines, suggesting that these signatures derive predominantly from infiltrating immune cells. All nine immune signatures achieved statistically significant associations with patient prognosis (p<0.05) in one or more tumor types with greatest significance observed in breast and skin cancers. Several signatures indicative of myeloid lineages exhibited poor outcome associations that were most apparent in brain and colon cancers.

Conclusions

These findings suggest that tumor infiltrating immune cells can be differentiated by immune-specific gene expression patterns that quantify the relative abundance of multiple immune infiltrates across a range of solid tumor types. That these markers of immune involvement are significantly associated with patient prognosis in diverse cancers suggests their clinical utility as pan-cancer markers of tumor behavior and immune responsiveness.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2948-z) contains supplementary material, which is available to authorized users.

Metastatic melanoma: Pathologic characterization, current treatment, and complications of therapy

Metastatic melanoma (MM) has the potential to involve virtually any anatomical site, and it also has a wide spectrum of histological appearances. General clinicopathologic data pertaining to MM are presented in this review, together with a discussion of its differential diagnosis and therapy. "Biological" agents used in the treatment of melanoma are considered, along with the pathological features of the complications that they may cause.

Angiogenesis in melanoma: an update with a focus on current targeted therapies

Angiogenesis plays a crucial role in melanoma metastasis and progression. In recent years, numerous studies have investigated the prognostic and clinical significance of this phenomenon, and the development of molecular techniques has enabled us to achieve a better understanding of angiogenesis in melanoma. Herein, we review the current state of knowledge regarding angiogenesis in melanoma, including the pathophysiological, histological and immunohistochemical aspects of this phenomenon. We also review the molecular pathways involved in angiogenesis and the interplay between different components that might be manipulated in the future development of efficient targeted therapies. Recently developed targeted antiangiogenic therapies in clinical trials and included in the treatment of advanced-stage melanoma are also reviewed.

Immunolabeling for p16, WT1, and Fli-1 in the assignment of growth phase for cutaneous melanomas

Distinction between radial growth phase (RGP) and vertical growth phase (VGP) in cutaneous melanomas is prognostically significant. Despite established morphological criteria, molecular markers to separate RGP and VGP have not been well established. The goal of this study was to investigate associations of p16, WT1, and Fli-1 with RGP-to-VGP progression, by immunohistochemistry. The p16 is a tumor suppressor, whereas WT1 and Fli-1 are transcriptional activators. The authors hypothesized that entry into VGP would be associated with decreased p16 and increased WT1 and Fli-1. Paraffin sections from 18 RGP and 15 VGP melanomas were immunostained with well-characterized antibodies to p16, WT1, and Fli-1. Melanoma growth phases were determined using precodified morphological attributes. In RGP melanomas, p16 was expressed in 15 of 18 (83%), WT1 in 17 of 17 (100%), and Fli-1 at least focally in 6 of 18 (33%). The deep dermal component of VGP melanomas stained positively for Fli-1 in 9 of 14 (64%), strongly for WT1 in 10 of 14 (71%), and strongly for p16 in only 2 of 15 (13%). Observed patterns of WT1 immunopositivity did not support the authors' hypothesis; it is not likely to be a good indicator of VGP. On the other hand, Fli-1 staining trended toward more positive deep tumor compartment staining and p16 to weaker staining in the deep compartment. At present, application of histological criteria remains the best method for assignment of growth phase in melanomas; however, p16 and possibly Fli-1 immunostains may serve as useful adjuncts in morphologically indeterminate cases.

Why is autophagy important for melanoma? Molecular mechanisms and therapeutic implications

As the principle lysosomal mediated mechanism for the degradation of aged or damaged organelles and proteins, autophagy (self-eating) is generally considered a pro-survival process activated by cells to sustain life in presence of adverse environmental conditions such as nutrient shortage and/or in presence of cytotoxic compounds. Upon activation, cytoplasmic material is sequestered into double-membrane vesicles (autophagosomes) then targeted for degradation by fusion with lysosomes (autolysosomes); metabolic activity and cell survival are consequently sustained by recycling the degradation products. Basal autophagy occurs in almost all cell types, though at different degree, as a finely regulated "quality control" process to prevent cell damage, for the demolition of cellular structures during cell/tissue remodelling, and to ensure the maintenance of cellular homeostasis through recycling cellular components/molecules. Autophagy is stimulated in response to both physiological and pathological conditions such as starvation, hypoxia and low energy, pathogen infection and protein aggregates. Although it's clear that autophagy is also involved in cancer, its role, however, is complex since it can both suppress and promote tumorigenesis. Consequently, it is generally accepted that while autophagy is used by advanced stage cancers to maintain tumour survival, loss of autophagy in earlier stages is associated with tumour development. Accordingly, it is now apparent that aberrant control of autophagy is among key hallmarks of cancer, with several studies now demonstrating this process is deregulated also in melanoma.

Innate immune sensing of cancer: clues from an identified role for type I IFNs

A subset of patients with a variety of cancers shows evidence of a natural adaptive immune response against their tumor, as evidenced by spontaneous T-cell infiltration, circulating anti-tumor T cells, or antibody responses. Evidence has indicated that such natural immune responses have positive prognostic import in early stage disease and may be predictive of clinical response to immunotherapeutics in advanced disease. However, these observations raise a new critical fundamental question-what innate immune signals might be generated in the context of non-pathogen-induced cancers that drive productive antigen presentation toward induction of an adaptive immune response? Gene expression profiling in melanoma revealed that tumors having high expression of T-cell markers also show evidence of a type I IFN transcriptional signature. Mechanistic experiments in mice have revealed that a spontaneous CD8(+) T-cell response against transplantable tumors depends on host type I IFN signaling, through a mechanism dependent upon CD8α(+) dendritic cells (DCs). The requirement for type I IFN production by host DCs has suggested a subset of innate immune sensing receptors and signaling pathways that might be involved with initiating this process. Elucidating further these innate immune mechanisms should provide new insights into cancer immunotherapy.

Influence of single nucleotide polymorphisms in the MMP1 promoter region on cutaneous melanoma progression

Recently, we reported on the associations of seven single nucleotide polymorphisms (SNPs) in the promoter region of MMP1 gene with susceptibility to cutaneous melanoma (CM). Considering the reported correlation between MMP1 expression and melanoma progression, we hypothesized that these promoter SNPs might affect CM progression and prognosis. In this study, we examined the associations of seven SNPs with overall survival, as well as six clinicopathological factors in 754 patients with CM. After adjustment for 11 covariates, we observed significant associations of the SNP -422A>T (rs475007) with ulceration status (P=0.012), primary tumor thickness (P=0.040), and anatomic site (P=0.030). We also observed significant associations of the SNP -755T>G (rs498186) with ulceration status (P=0.038) and anatomic site (P=0.003). Two SNPs, -839G>A and -519A>G, were marginally associated with primary tumor thickness, ulceration status, and anatomic site. Furthermore, the frequency of haplotype 2G-G-G-A-A-G-T was higher in patients with ulceration (odds ratio=2.18, 95% confidence interval: 1.08-4.40, P=0.030) compared with those without ulceration. However, we did not find significant associations of these SNPs with overall survival and other clinical factors. As primary tumor thickness and ulceration status are two important indicators of tumor progression and have significant associations with melanoma prognosis, our results suggested that these promoter SNPs in MMP1 might have potential effects on melanoma progression and prognosis by influencing related clinical factors.

Thigmotropism of malignant melanoma cells

During malignant melanoma (MM) progression including incipient metastasis, neoplastic cells follow some specific migration paths inside the skin. In particular, they progress along the dermoepidermal basement membrane, the hair follicles, the sweat gland apparatus, nerves, and the near perivascular space. These features evoke the thigmotropism phenomenon defined as a contact-sensing growth of cells. This process is likely connected to modulation in cell tensegrity (control of the cell shape). These specifically located paucicellular aggregates of MM cells do not appear to be involved in the tumorigenic growth phase, but rather they participate in the so-called "accretive" growth model. These MM cell collections are often part of the primary neoplasm, but they may, however, correspond to MM micrometastases and predict further local overt metastasis spread.

Smouldering malignant melanoma and metastatic dormancy: an update and review

The fund of knowledge regarding the versatility of presentation of MM metastases is still quite incomplete. The recent literature pertaining to the current understanding of the mechanisms underlying two special features of MM metastasis is reviewed. On the one hand, a long disease-free interval (MM dormancy) may occur before the surge of overt metastases. On the other hand, the so-called MM smouldering phenomenon refers to the condition where regional metastases wax and wane for long periods of time on restricted skin regions. It is important to emphasize that local micrometastases often predict sentinel lymph node involvement but may not reflect progression of the primary MM to full-blown visceral metastatic competence. It is likely that a combination of factors impacts the versatile MM metastasic progression. Among the main factors, one has to mention the phenotypic heterogeneity and variability in the phenotype of MM cells, the presence of MM stem cells and MM cells engaged in an amplification proliferation pool, as well as the host immune response, and possibly the induction of a particular stromal structure and vascularity.

Comparison Among Clark's, Breslow's, and TNM classifications for cutaneous head and neck malignant melanoma

This retrospective study was carried out to assess the prognostic value of three classification systems used for staging cutaneous head and neck malignant melanoma (CHNME). Fifty-three patients with histologically proven CHNME were analyzed. Thirty patients were never treated before admission, whereas 23 (43.4%) had a second radical resection of the primary tumor location, 9 (17%) had neck nodes, none had distant metastasis, and all had a minimum of 5 years of follow-up. Results show that T-stage is the most important clinical prognostic parameter, whereas Clark's and Breslow's classifications have lower impact in defining prognosis. Sites of primary tumor determines different clinical outcomes, but this does not reach statistically significant values. A second surgery on the primary tumor location is possible and is effective toward survival. No statistical differences were noted between the previously untreated and treated groups. Neck nodes have to be removed with neck dissection, and this regimen can improve the clinical outcome; however, only 40% of neck positive patients survive more than 5 years.

Angiogenesis in melanoma

The process of angiogenesis is crucial for progression and metastasis of the majority of solid tumors including melanomas. The current review summarizes existing knowledge of the mechanisms of angiogenesis in melanoma, as well as current anti-angiogenic therapeutic strategies and their targets. We focus primarily on the role of key growth factors that are secreted by melanoma cells and known to trigger angiogenic responses, and their receptors as expressed on both endothelial and melanoma cells. Many of these growth factors function in synergy with receptors for extracellular matrix, integrins, and matrix metalloproteinases (MMPs). All of these systems of molecules are activated during major stages of angiogenesis such as endothelial migration, proliferation, and reorganization of surrounding extracellular matrix. The blockade of these molecules and their downstream pathways leads to inhibition of melanoma vascularization. Thus, these classes of molecules are essential for melanoma angiogenesis and, therefore, might serve as promising targets for therapeutic intervention. Many recently developed compounds targeting key pathways in angiogenesis are in their final stages of clinical trials.

Biologic and prognostic significance of dermal Ki67 expression, mitoses, and tumorigenicity in thin invasive cutaneous melanoma

PURPOSE

Tumor cell proliferation is a central feature of melanoma progression. In this study, we characterized three biomarkers of proliferation (Ki67 expression, dermal mitotic rate [MR], and tumorigenicity) in thin (< or = 1.00 mm) primary cutaneous melanomas and examined their association with prognosis.

PATIENTS AND METHODS

We used immunohistochemistry to determine Ki67 expression using the monoclonal antibody MIB-1 in lesions from a prospective cohort that included 396 patients with thin invasive primary melanomas seen between 1972 and 1991. A multivariate Cox proportional hazards model was used to define independent prognostic factors, and recursive partitioning was used to develop a prognostic tree identifying risk groups.

RESULTS

Dermal Ki67 expression was lower than epidermal Ki67 expression in radial growth phase (RGP) melanomas (n = 171), and dermal Ki67 expression and MR were higher in tumorigenic vertical growth phase (VGP) melanomas (n = 193) compared with RGP and nontumorigenic VGP melanomas (n = 42). Dermal Ki67 expression, MR greater than 0, growth phase, thickness, ulceration, tumor-infiltrating lymphocytes, and sex were associated with metastasis at 10 years, however, only dermal Ki67 expression, MR greater than 0, and sex were independent prognostic factors. Two high-risk groups were identified: men and women with dermal MR greater than 0 and dermal Ki67 expression > or = 20% in tumor cells and men with MR greater than 0 and Ki67 expression less than 20%, with 10-year metastasis rates of 39% and 20%, respectively.

CONCLUSION

Proliferation slows as melanoma cells enter the dermis and then increases with the onset of tumorigenic VGP. Ki67 expression and dermal MR provide independent prognostic information that can potentially be used in risk-based management of patients.

Incidence of BRAF oncogene mutation and clinical relevance for primary cutaneous melanomas

PURPOSE

The purpose of the study was to clarify the incidence of B-raf oncogene (BRAF) mutations in primary cutaneous melanomas, their relation to tumor progression, and effect on disease outcome. Somatic mutations of BRAF kinase, a component of the Ras-mitogen-activated protein/extracellular signal-regulated kinase kinase-mitogen-activated protein kinase pathway, are frequently reported (>65%) in nevi and malignant melanomas.

EXPERIMENTAL DESIGN

We assessed BRAF mutation frequency in exons 11 and 15 in primary (n = 59) and metastatic (n = 68) melanomas. Direct sequencing of PCR products was performed on DNA isolated and purified from microdissected tumors.

RESULTS

Eighteen mutations (31%) at exon 15 were detected in primary melanoma with a significantly (P = 0.001) higher frequency in patients < 60 years old. Incidence of BRAF mutation did not correlate with Breslow thickness. Presence of BRAF mutation of primary tumors did not effect overall disease-free survival. BRAF mutation frequency in metastatic lesions was 57% and significantly (P = 0.0024) higher than primary melanomas.

CONCLUSIONS

The study suggests that BRAF mutation may be acquired during development of metastasis but is not a significant factor for primary tumor development and disease outcome.

Narrower Surgical Margins Might be Sufficient in Invasive Horizontal Growth Phase Melanoma

Background and Aims

The delineation of horizontal and vertical growth phases in primary cutaneous melanoma has contributed to our understanding of melanoma progression. Horizontal growth phase invasive melanomas are now believed to metastasize very rarely. Consequently, some of us have started to treat these lesions with very limited surgical margins, assuming that in terms of biological behavior this type of melanoma is more similar to an in situ than an invasive lesion.

Methods

Between January 1997 and December 2001 42 lesions of this type in 41 patients (24 women and 17 men) were treated in the outpatient clinic under local anesthesia. The excision margin was half a centimeter and the subcutaneous fat was cleared in most cases to the deep fascia, which was conserved. Loss was made good by direct tissue closure. All patients had undergone an excisional biopsy before definitive surgery. The size of the lesions ranged from 2 mm to 19 mm in maximum linear extent (median 7 mm). Lesion thickness ranged from 0.11 mm to 0.58 mm (median, 0.27 mm).

Results

The median follow-up was 47 months (range, 26-83). During this period none of the patients had locoregional or distant relapses.

Conclusions

This preliminary report seems to corroborate the assumption that horizontal growth phase melanoma is not an aggressive lesion and might therefore be cured by non-aggressive surgery. The proper treatment of such lesions might be a surgical excision at half a centimeter distance from the biopsy scar. This approach may produce very good cosmetic results, while keeping the costs and required resources to a minimum.

Relevance of vertical growth pattern in thin level II cutaneous superficial spreading melanomas

Thin (<or=0.76 mm) level II cutaneous superficial spreading melanomas (SSMs) are known to be of excellent prognosis and very few recur, metastasize, or are lethal. Although many prognostic features at this stage have been studied, none appears to be statistically significant. The concept of tumor growth phase is correlated with Clark's level except for level II. SSM level II show either an invasive vertical growth phase or an invasive radial growth phase. The aim of our study (retrospective, multicenter, and case-control type) was to investigate the prognostic impact of vertical growth phase in thin level II cutaneous SSM. We identified 12 patients of poor outcome with complete initial excision. Each case was matched with three controls for gender, age, location, tumor thickness, and follow-up period since diagnosis. Independent pathologists studied all cases and controls. Univariate analyses were performed with a conditional logistic regression method. A kappa test was used to assess reproducibility between pathologists. Our study is the first and largest that shows that vertical growth phase is the only statistically significant prognostic factor for thin level II cutaneous SSM. We propose that growth phase evaluation (a minimum of eight serial sections being mandatory not to underdiagnose vertical growth phase) should be added to the recommendations for melanoma histologic report, at least for level II SSM.

Problems in the interpretation of apparent "radial growth phase" malignant melanomas that metastasize

BACKGROUND

The delineation of radial and vertical growth phases in primary cutaneous malignant melanomas has contributed to our understanding of melanoma progression and has enhanced the ability of pathologists to provide clinicians with meaningful prognostic information. Vertical growth phase (VGP) lesions have the potential to metastasize, but radial growth phase (RGP) melanomas are believed to lack competence for metastasis.

METHODS

We have identified three cases in which metastasis occurred in association with lesions initially interpreted as RGP melanomas. To determine whether these cases truly represented exceptional metastasizing RGP melanomas or VGP lesions incorrectly identified as RGP lesions, careful microscopic re-review of these cases was performed.

RESULTS

In one case, additional microscopic sectioning revealed a focus of vertical growth that was not evident on the original sections. In the other two cases, only radial growth was found. In one of these cases there was melanoma in situ with regressive changes, but no evidence for invasive melanoma. In the other, a RGP lesion was associated with an adjacent compound nevus with periadnexal involvement.

CONCLUSIONS

These cases suggest that, while true RGP melanomas have an excellent prognosis, caution must be exercised in defining a lesion as having no metastatic potential when multiple sections of the primary lesion are unavailable, when the lesion is accompanied by regressive changes, or when there is an associated melanocytic nevus. It is possible that strictly defined RGP melanomas may metastasize in very rare cases. Our observations also suggest that metastatic potential is a function of numerous factors, and may not be evaluable on morphological grounds alone.

Spectrophotometric intracutaneous analysis: a new technique for imaging pigmented skin lesions

BACKGROUND

Spectrophotometric intracutaneous analysis (SIA) is a new technique for imaging pigmented skin lesions and for diagnosing melanoma. The SIAscope produces eight narrow-band spectrally filtered images of the skin over an area of 24 x 24 mm with radiation ranging from 400 to 1000 nm.

OBJECTIVES

To present the early results of a clinical trial with SIA.

METHODS

Spectrophotometric inputs from the skin were analysed using complex algorithms to return high-resolution information regarding total melanin content of the epidermis and papillary dermis, collagen and haemoglobin content as well as the presence of melanin in the papillary dermis.

RESULTS

Simple, highly reproducible and reliable features were identified, e.g. the presence of dermal melanin, collagen holes and 'erythematous blush' with blood displacement. These simple features were found to be highly specific (80.1%) and sensitive (82.7%) for melanoma in a dataset of 348 pigmented lesions (52 melanomas) and compared very favourably with dermatoscopy when analysed using receiver-operator characteristic curves.

CONCLUSIONS

This first clinical trial with SIAscopy has yielded very promising results and delivers new, useful information to the clinician diagnosing pigmented skin lesions.

Microstaging in cutaneous melanoma

Recent papers have addressed critical issues regarding the microstaging of cutaneous melanoma. They concern the new staging proposal by the American Joint Committee on Cancer (AJCC), the presentation of new prognostic models than seem applicable in daily practice, and new immunohistochemical findings than demonstrate prognostic information independently of the conventional major factors. These issues are commented on by the Pathology Committee of the EORTC Melanoma Group.

Loss of expression of protein kinase C beta is a common phenomenon in human malignant melanoma: a result of transformation or differentiation?

As with most cancers, the aetiology of human cutaneous melanoma is likely to be multifactorial and to include the accumulation of irreversible alterations in an unknown number of genes. Elucidating this molecular progression necessitates both the identification of genetic perturbations at each clinically relevant stage, and the assessment of their impact on the normal melanocyte. The observation that the epidermal melanocyte, in contrast to metastatic melanoma cells, requires activation of the protein kinase C (PKC) pathway to facilitate growth in vitro indicates that one or more isoforms (or substrates) of this large and complex family of proteins are among those that undergo alteration during the development of malignant melanoma. Consequently, a number of studies have investigated the expression of various PKC family members in both melanocyte and melanoma cell lines, without a consensus of opinion as to which isoforms are of biological significance in melanoma development and progression. The present study involved a comprehensive evaluation of the PKC profile in normal melanocytes and in 16 metastatic melanoma cell lines. The results show that the major difference in isoform expression between epidermal melanocytes and melanoma cells is the loss of PKCbeta protein expression in 90% of melanoma cell lines. Examination of PKCbeta in benign and malignant melanocytic lesions revealed that this protein is either downregulated or absent in both naevi and metastatic melanomas. We conjecture that, although the loss of PKCbeta expression is a common phenomenon in malignant melanocytes, it may be related more to a normal process of melanocytic differentiation than to malignant transformation.

Differentiation therapy of human cancer: basic science and clinical applications

Current cancer therapies are highly toxic and often nonspecific. A potentially less toxic approach to treating this prevalent disease employs agents that modify cancer cell differentiation, termed 'differentiation therapy.' This approach is based on the tacit assumption that many neoplastic cell types exhibit reversible defects in differentiation, which upon appropriate treatment, results in tumor reprogramming and a concomitant loss in proliferative capacity and induction of terminal differentiation or apoptosis (programmed cell death). Laboratory studies that focus on elucidating mechanisms of action are demonstrating the effectiveness of 'differentiation therapy,' which is now beginning to show translational promise in the clinical setting.

TIA-1 positive tumor-infiltrating lymphocytes in nevi and melanomas

Tumor-infiltrating lymphocytes (TIL) have been shown to be an independent prognostic factor in melanomas. To better characterize the host immune response, we have classified TIL by their immunoreactivity against lymphoid markers in formalin-fixed, paraffin-embedded tissue. Monoclonal antibodies to leukocyte common antigen (LCA) and TIA-1 (a granule-associated protein of cytotoxic T cells and NK cells) were used to immunostain a series of benign nevi, nontumorigenic radial growth phase, and tumorigenic vertical growth phase melanomas and metastases. Among nine nevi, few LCA+ TIL were found, among which rare cells were positive for TIA-1 (mean, 2.0). Five nontumorigenic radial growth phase melanomas also had few total TIL and rare TIA-1+ TIL (mean, 3.4); the nontumorigenic radial growth phase component of seven tumorigenic vertical growth phase melanomas had higher numbers of TIA-1+ TIL (mean, 11). Twelve cases of tumorigenic vertical growth phase melanoma showed a variable but significantly greater number of both LCA+ TIL and TIA-1+ TIL (mean, 30.6). Nine cases of metastatic melanoma had a wide range of variation in LCA as well as in TIA-1+ TIL (mean, 46). Although the mean total number of TIA-1+ TIL increased from nontumorigenic radial growth phase to tumorigenic vertical growth phase to metastases, TIA-1+ as a percentage of TIL declined across these categories of tumor progression (42%, 31%, and 26%, respectively). Our results show that these attributes of TIA-1+ TIL, both increasing total number but decreasing percentage, appear to be a marker of tumor progression of malignant melanomas. In addition, there was significant variability in the number of TIA-1+ TIL among advanced melanomas, raising the possibility that an assessment of TIA-1+ TIL may prove a useful prognostic tool for the evaluation of primary melanomas.

Tumor progression, early diagnosis and prognosis of melanoma

Primary melanomas evolve from melanocytes or from precursor lesions through two stages: the radial and vertical growth phases. The radial growth phase may be in situ or microinvasive, but is a non-tumorigenic neoplastic process, while the vertical growth phase is tumorigenic. The prognosis in radial growth phase is excellent irrespective of thickness or other variables. Curable radial growth phase melanomas can be recognized by surveillance of patients identified by screening for risk markers which include dysplastic nevi, common nevi, freckles, and other indicators of chronic or acute sun exposure or sun sensitivity. The prognosis in vertical growth phase depends on attributes of the tumor and of the host. The tumor mitotic rate, the presence of host tumor-infiltrating lymphocytes (TIL) within the vertical growth phase, and tumor thickness are the most powerful predictors of survival. New prognostic attributes are needed not only to provide for more accurate prognosis and diagnosis, but also to test the relevance of in vitro or animal studies in a human neoplastic system. Such attributes will be developed in the future based on markers that are associated with tumor progression. Candidate markers include growth factors and cytokines and their receptors, adhesion molecules and their ligands, chemotactic and motility factors, immune response-related molecules, and tumor-associated proteases. Some of these markers that are represented in the transition from radial to vertical growth phase will be reviewed. The tumor progression model presented here has been of value in the development of more accurate prognostic models, and in the elucidation of mechanisms of the malignant phenotype in melanoma.

Advances in management of melanoma

It is clear from the above that the sentinel node technique and assessment of circulating melanoma cells has provided important additional methods for staging and assessment of prognosis of patients with melanoma. Cure of the disease still depends on good quality surgery and implementation of quality control measures to ensure the adequacy of surgical removal of primary melanoma and regional lymph node metastases is fundamental to improvement in survival from the disease. Systemic medical treatments have yet to show any significant impact on the disease when given in an adjuvant setting or in treatment of metastatic disease. There is much hope that new initiatives in immunotherapy and in apoptosis research will provide more effective treatments of the disease.