Correlation of Ki-67 expression in cutaneous primary melanoma with prognosis in a prospective study: different correlation according to thickness.

BACKGROUND: The proliferative activity of melanoma cells, evaluated as MIB-1 immunoreactivity against a Ki-67 epitope, has been considered an indicator of poor prognosis in thick primary melanomas. OBJECTIVE: The aim of the study was to assess the correlation between the growth fraction of primary melanomas, assessed by means of Ki-67 immunoreactivity, and metastatic relapse. METHODS: Ki-67 reactivity in primary melanomas was evaluated as at least 5% of positive neoplastic cells and was assessed on fresh specimens of 55 primary lesions at the time of excision. Such reactivity was correlated with metastatic relapse of patients in a prospective study, by means of multivariate Cox regression models (follow-up, 3-120 months). RESULTS: Ki-67 immunoreactivity was associated with increasing thickness (P =.003). Positive correlation was found between Ki-67 reactivity and metastatic dissemination in primary melanomas less than 1.5 mm thick (n = 23; mean thickness, 0.75 +/- 0.3 mm; P =.002). On the contrary, a negative correlation was found between Ki-67 reactivity and metastatic activity in primary melanomas thicker than 1.5 mm (n = 32; mean thickness, 4.0 +/- 1.6 mm; P =.019). CONCLUSION: Ki-67 proliferative activity appears to be a possible predictor of metastasis in primary melanomas, in particular, an indicator of poor prognosis in lesions less than 1.5 mm thick.

Molecular detection of microsatellite instability in basal cell carcinoma.

Several studies have shown that the presence of genetic instability can be associated to carcinogenesis process. The detection of microsatellite instability (MI) that consists of an expansion and/or deletion of DNA within repeat sequences, may constitute a sensitive marker for the presence of gene mutations. A series of 18 basal cell carcinoma (BCC) consecutive patients was examined for the presence of alteration in 12 DNA microsatellite markers, in order to better understand the molecular significance of MI in the genesis and progression of BCC. Molecular alterations were detected in 6 out of 12 analyzed microsatellite loci. Five out of 18 BCC samples showed loss of heterozygosity at chromosome loci localized in the vicinity of the tumor suppressor genes, whereas six out of 18 BCC patients presented at least one altered microsatellite (instability). We demonstrated molecular genetic alterations at 2p16 locus, in the proximity of MSH2 gene and 17p21, in the proximity of the p53 gene. These data validate and confirm a role of MI in genesis and progression of BCC, by analysis of markers localized at specific chromosome region in proximity of oncogenes and tumor suppressor genes.

Immunohistochemical evidence of cytokine networks during progression of human melanocytic lesions.

Melanoma cells in culture express a variety of growth factors and cytokines and some of their autocrine and paracrine roles have been investigated. However, less information is available on the potential dynamic changes in expression of these molecules on cells during melanoma development and progression in situ. Using immunohistochemistry, we tested 40 nevi and primary and metastatic melanoma lesions for the expression of 10 growth factors and cytokines and the respective receptors representing 10 cell surface molecules. Nevi and thin (< 1 mm) primary melanomas showed little expression of ligands except weak reactivity of tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta), interleukin-8 (IL-8) and reactivity of TGF-betaR and c-kit. Marked up-regulation of growth factors, cytokines and receptor expression was observed in thick (> 1 mm) primary melanomas, which were stained with polyclonal or monoclonal antibodies (MAbs) for IL-1alpha, IL-1beta, IL-6, IL-8, TNF-alpha, TGF-beta, granulocyte-macrophage colony-stimulating factor (GMCSF) and stem cell factor (SCF), but not IL-2. Metastases showed similar expression patterns except that SCF was absent. Co-expression of ligand and receptor was observed for TGF-beta, GM-CSF and IL-6, suggesting an autocrine role for these ligands. TNF-alpha appears to be a marker of benign lesions; IL-6 and IL-8 expression is associated with biologically early malignancy; TGF-beta, GM-CSF and IL-1alpha are highly expressed in biologically late lesions; and TNF-beta is an apparent marker of metastatic dissemination. Our results indicate that melanoma cells utilize cascades of growth factors and cytokines for their progression.

In situ expression of transforming growth factor beta is associated with melanoma progression and correlates with Ki67, HLA-DR and beta 3 integrin expression.

Transforming growth factor-beta (TGF beta), which is secreted by cultured melanoma cells constitutively, inhibits the proliferation of normal melanocytes and of most melanoma cells in vitro, but some melanoma cells from advanced stages of the disease develop resistance to TGF beta-dependent growth inhibition, without developing any change in TGF beta cell surface binding. In vitro TGF beta also downregulates the expression of HLA-DR molecules on melanoma cells, and upregulates the expression of the beta 3 integrin subunit on some cell lines. Immunohistochemical analysis of 53 melanocytic lesions (12 naevi, 30 primary melanomas and 11 metastases) revealed a trend of increasing expression of TGF beta and TGF beta receptor type III with tumour progression, and a significantly higher expression of both TGF beta (P < 0.0001) and the receptor (P < 0.05) in metastatic and thick (> 1 mm) primary melanomas compared with thin (< 1 mm) primary melanomas. The expression of TGF beta correlated with expression of a marker of proliferation, Ki67, and with HLA-DR and beta 3 integrin subunit expression. Coexpression of the four molecules was observed in all metastases and in most thick primary melanomas. These findings argue against an inhibitory effect of TGF beta on cell proliferation or HLA-DR antigen expression in melanoma, and suggest the upregulation of the beta 3 subunit. TGF beta protein appears to be a biological marker of melanoma progression in situ.

Adhesion molecule profile and malignancy of melanocytic lesions.

The ability of melanoma cells to metastasize is largely dependent upon cell surface molecules that mediate cell-matrix and cell-cell interactions. Our aim was to investigate the expression of such molecules (adhesion molecules) on tissue sections of a series of melanocytic lesions in different stages of tumour progression. Four common naevi, four congenital naevi, four dysplastic naevi, three Spitz naevi, 20 primary melanomas and 15 metastatic melanomas were tested with an alkaline phosphatase/anti-alkaline phosphatase technique and a panel of monoclonal antibodies directed toward different alpha subunits of VLA receptors, beta 1, VNR-alpha and beta 3 subunit, and CD44 hyaluronate receptor. Only metastatic melanomas expressed the alpha 4 subunit, and only thick primary melanomas and metastases expressed the beta 3 subunit. The alpha 6/beta 1 chain was expressed at significantly higher levels on benign lesions, and a trend towards increased expression of alpha 2 and alpha 3 subunits was found in malignant versus benign lesions. Our results show that the pattern of integrin expression changes in melanocytic lesions along with malignant transformation.