The immunohistochemical profile of Spitz nevi and conventional (non-Spitzoid) melanomas: a baseline study.

Several isolated markers have been proposed to aid in differential diagnostic of difficult melanocytic lesions, albeit none has been shown to be definitive in differentiating Spitz nevus from melanoma. This study proposes a wide panel of 22 markers having important functions in different biological functions (cell cycle, apoptosis, DNA repair proteins and membranous receptors) to provide a combination of proteins associated with either benign or malignant phenotype. Using tissue microarrays, we compared protein expression profiles in 28 typical Spitz nevi and 62 primary vertical growth phase non-spitzoid melanomas. Most of the significant differences were linked to cell-cycle deregulation such as overexpression of cyclin D1 and p21 in Spitz nevi compared with non-spitzoid melanomas (74 vs 16% and 91 vs 27%, respectively) and mitotic rate including Ki-67, highly expressed in deep areas of non-spitzoid melanomas (37%), whereas it is not expressed in Spitz nevi (0%), topoisomerase IIalpha (79% in non-spitzoid melanomas vs 15% in Spitz nevi) and nuclear survivin (69% in melanomas vs 0% in Spitz nevi). A combination of biological markers differentially expressed in Spitz nevi from non-spitzoid melanomas is defined, thus providing a potential tool for histopathological differential diagnostic between Spitz nevus and melanoma. Nevertheless, more studies including atypical Spitz nevi and spitzoid melanomas are necessary to further establish a reliable panel to differentiate among difficult cases.

A high-throughput study in melanoma identifies epithelial-mesenchymal transition as a major determinant of metastasis.

Metastatic disease is the primary cause of death in cutaneous malignant melanoma (CMM) patients. To understand the mechanisms of CMM metastasis and identify potential predictive markers, we analyzed gene-expression profiles of 34 vertical growth phase melanoma cases using cDNA microarrays. All patients had a minimum follow-up of 36 months. Twenty-one cases developed nodal metastatic disease and 13 did not. Comparison of gene expression profiling of metastatic and nonmetastatic melanoma cases identified 243 genes with a >2-fold differential expression ratio and a false discovery rate of <0.2 (206 up-regulated and 37 down-regulated). This set of genes included molecules involved in cell cycle and apoptosis regulation, epithelial-mesenchymal transition (EMT), signal transduction, nucleic acid binding and transcription, protein synthesis and degradation, metabolism, and a specific group of melanoma- and neural-related proteins. Validation of these expression data in an independent series of melanomas using tissue microarrays confirmed that the expression of a set of proteins included in the EMT group (N-cadherin, osteopontin, and SPARC/osteonectin) were significantly associated with metastasis development. Our results suggest that EMT-related genes contribute to the promotion of the metastatic phenotype in primary CMM by supporting specific adhesive, invasive, and migratory properties. These data give a better understanding of the biology of this aggressive tumor and may provide new prognostic and patient stratification markers in addition to potential therapeutic targets.

Gene expression profiling of primary cutaneous melanoma and clinical outcome.

BACKGROUND: Gene expression profiling data for human primary cutaneous melanomas are scarce because of the lack of retrospective collections of frozen tumors. To identify differentially expressed genes that may be involved in melanoma progression and prognosis, we investigated the relationship between gene expression profiles and clinical outcome in a cohort of patients with primary melanoma. METHODS: Labeled complementary RNA (cRNA) from each tissue sample was hybridized to a pangenomic 44K 60-mer oligonucleotide microarray. Class comparison and class prediction analyses were performed to identify genes whose expression in primary melanomas was associated with 4-year distant metastasis-free survival among 58 patients with at least 4 years of follow-up, distant metastasis, or death. Results were validated immunohistochemically at the protein level in 176 independent primary melanomas from patients with a median clinical follow-up of 8.5 years. Survival was analyzed with a Cox multivariable model and stratified log-rank test. All statistical tests were two-sided. RESULTS: We identified 254 genes that were associated with distant metastasis-free survival of patients with primary melanoma. These 254 genes include genes involved in activating DNA replication origins, such as minichromosome maintenance genes and geminin. Twenty-three of these genes were studied at the protein level; expression of five (MCM4, P = .002; MCM3, P = .030; MCM6, P = .004; KPNA2, P = .021; and geminin, P = .004) was statistically significantly associated with overall survival in the validation set. In a multivariable Cox model adjusted for tumor thickness, ulceration, age, and sex, expression of MCM4 (hazard ratio [HR] of death = 4.04, 95% confidence interval [CI] = 1.39 to 11.76; P = .010) and MCM6 (HR of death = 7.42, 95% CI = 1.99 to 27.64; P = .003) proteins was still statistically significantly associated with overall survival. CONCLUSION: We identified 254 genes whose expression was associated with metastatic dissemination of cutaneous melanomas. These genes may shed light on the molecular mechanisms underlying poor prognosis in melanoma patients.

Progression in cutaneous malignant melanoma is associated with distinct expression profiles: a tissue microarray-based study.

Cutaneous malignant melanoma remains the leading cause of skin cancer death in industrialized countries. Clinical and histological variables that predict survival, such as Breslow's index, tumor size, ulceration, or vascular invasion have been identified in malignant melanoma. Nevertheless, the potential relevance of biological variables still awaits an in-depth exploration. Using tissue microarrays (TMAs), we retrospectively analyzed 165 malignant melanoma samples from 88 patients corresponding to distinct histological progression phases, radial, vertical, and metastases. A panel of 39 different antibodies for cell cycle, apoptosis, melanoma antigens, transcription factors, DNA mismatch repair, and other proteins was used. Integrating the information, the study has identified expression profiles distinguishing specific melanoma progression stages. Most of the detected alterations were linked to the control of cell cycle G1/S transition; cyclin D1 was expressed in radial cases 48% (12 of 25) with significant lost of expression in vertical cases 14% (9 of 65), P = 0.002; whereas p16(INK4a) (89% in vertical versus 71% in metastatic cases, P = 0.009) and p27(KIP1) (76% in radial versus 45% in vertical cases, P = 0.010) were diminished in advanced stages. The study also defines a combination of biological markers associated with shorter overall survival in patients with vertical growth phase melanoma, that provided a predictor model with four antibodies (Ki67, p16(INK4a), p21(CIP1), and Bcl-6). This predictor model was validated using an independent series of 72 vertical growth phase melanoma patients.