SOX10 expression in superficial spreading and nodular malignant melanomas.

SOX10 is a transcription factor expressed in nerve cells and melanocytes. The aim of this study was to investigate the protein expression pattern of SOX10 in malignant melanoma tumors and to analyze whether the results correlated with clinical parameters and the proliferation marker Ki-67. Furthermore, proliferation and migration were analyzed in three different cell lines employing SOX10 small interfering RNA-mediated silencing. Expression patterns were determined in 106 primary tumors and 39 metastases in addition to 16 normal skin samples and six benign nevi employing immunohistochemistry and tissue microarrays. The immunohistochemical staining was evaluated manually and with an automated algorithm. SOX10 was strongly expressed in the benign tissues, but for the malignant tumors superficial spreading melanomas stained stronger than nodular malignant melanomas (P=0.008). The staining intensity was also inversely correlated with T-stage (Spearman's ρ=-0.261, P=0.008). Overall survival and time to recurrence were significantly correlated with SOX10 intensity, but not in multivariate analysis including T-stage. With the automated algorithm there was an inverse correlation between the SOX10 staining intensity and the proliferation marker, Ki-67 (ρ=-0.173, P=0.02) and a significant difference in the intensity signal between the benign tissues, the primary tumors and the metastases where the metastases stained the weakest (P≤0.001). SOX10 downregulation resulted in variable effects on proliferation and migration rates in the melanoma cell lines. In conclusion, the SOX10 intensity level differed depending on the tissue studied and SOX10 might have a role in survival. No conclusion regarding the role of SOX10 for in-vitro proliferation and migration could be drawn.

Selective expression of Syntaxin-7 protein in benign melanocytes and malignant melanoma.

To search for proteins expressed in human melanocytes and melanoma, we employed an antibody-based proteomics strategy to screen for protein expression in tissue microarrays containing normal tissues, cancer tissues and cell lines. Syntaxin-7 (STX7) was identified as a novel protein, not previously characterized in cells of melanocytic lineage, displaying a cell type-specific protein expression pattern. In tumor tissues, STX7 was expressed in malignant melanoma and lymphoma. The protein was further characterized regarding subcellular localization, specificity, tissue distribution pattern and potential as a diagnostic and prognostic marker using cell lines and tissue microarrays containing normal skin, melanocytic nevi and primary and metastatic melanoma. STX7 was expressed in normal melanocytes, various benign melanocytic nevi, atypical nevi and malignant melanoma. Analysis in two independent melanoma cohorts demonstrated STX7 expression in nearly all investigated tumors, although at varying levels (> 90% positive tumors). The expression level of STX7 protein was inversely correlated to tumor stage, suggesting that decreased expression of STX7 is associated with more aggressive tumors. In conclusion, we present protein profiling data for a novel protein showing high sensitivity and specificity for cells of the melanocytic lineage. The presented antibody-based proteomics approach can be used as an effective strategy to identify novel tumor markers and evaluate their potential clinical relevance.

Serological and immunohistochemical analysis of S100 and new derivatives as markers for prognosis in patients with malignant melanoma.

The incidence of cutaneous malignant melanoma is rising, and tumour markers are attracting attention as a possible alternative to clinical examination in the follow-up situation. S100 is the preferred marker for malignant melanoma, and correlation between serum S100 and disease relapse and survival has been reported. S100 tests previously used in clinical studies were specified poorly regarding reactivity with S100A1B and S100BB. In this study, a newly designed S100 assay (designed to measure exclusively S100A1B and S100BB) and two newly developed serological assays, S100A1B, and S100BB, were investigated postoperatively in patients undergoing radical surgery for cutaneous malignant melanoma. Additionally, immunohistochemical analysis of S100A4 was performed on the primary malignant melanoma using tissue microarrays. The primary aim of the study was to investigate whether any of these assays, either singly or in combination, can contribute additional information concerning increased risk of relapse and death because of malignant melanoma. In total, 98 patients (54 males, 44 females) with malignant melanoma were included in the study. As a continuous variable, S100BB (P=0.016) was associated statistically with increased risk of relapse; this was not the case for increased values of either S100 (P=0.11) or S100A1B (P=0.92). The Kaplan-Meier overall survival as well as disease specific survival curve for the S100 serum level demonstrated a statistically significant association with better survival if the patient had a S100 level

The protein expression of TRP-1 and galectin-1 in cutaneous malignant melanomas.

BACKGROUND: Patients with metastazing malignant melanoma have a poor outcome and determination of thickness of the primary tumor remains as the most important prognostic predictor. The aim of this study was to use an antibody-based proteomics strategy to search for new molecular markers associated with melanoma progression. Two proteins, TRP-1 and galectin-1, were identified as proteins with enhanced expression in cells from the melanocytic lineage. PATIENTS AND METHODS: Protein profiling of TRP-1 and galectin-1 together with proliferation marker Ki-67 and melanocyte marker Melan-A was performed in normal tissues from 144 individuals and in 216 different tumors using tissue microarrays and immunohistochemistry. The protein expression pattern was further analyzed in a defined cohort of 157 patients diagnosed with invasive cutaneous malignant melanoma. RESULTS: Both TRP-1 and galectin-1 were highly expressed in normal melanocytes and melanoma. The expression of TRP-1 was inversely correlated with tumor stage (p=0.002, (R=-0.28)). Neither TRP-1 or galectin-1 was associated with overall or disease free survival (p>0.14, p>0.46 respectively). Ki-67 was associated with tumor stage and survival (p<0.001). CONCLUSION: TRP-1 and galectin-1 protein expression patterns were determined in normal and cancer tissues and both proteins were expressed in the majority of the malignant melanomas. There was no correlation between TRP-1 or galectin-1 expression and survival.

The role of circulating angiogenic factors in patients operated on for localized malignant melanoma.

Malignant melanoma is a disease capable of rapid progression and rapidly developing metastases. Angiogenesis is a key event signalling tumour progression and elevated levels of angiogenic markers may indicate metastatic disease. No previously published work has, so far, examined plasma vascular endothelial growth factor (VEGF) and its receptor, VEGFR-1, in melanoma. This study investigated circulating levels of the angiogenic factors, VEGF-A and -D, their receptors 1-3 and hepatocyte growth factor (HGF)/scatter factor, in patients shortly after primary surgery for localized malignant melanoma. Elevated circulating levels of VEGF and its receptors, and of HGF, were found postoperatively, possibly derived from the reactive stroma adjacent to the tumours. Using univariate analysis, a correlation between levels of VEGFR-1 and relapse was found, but a correlation between the investigated angiogenic factors and survival could not be established. The results of the present study indicate that production of these angiogenic factors may be due to sources other than malignant melanoma cells.