Novel Candidate Biomarkers in Melanomas Figure 7. Hierarchical Clustering and Network Analyses Revealed Novel Gene Interactions in Melanoma Progression. (A) Heatmap of five patient-derived metastatic melanoma cell lines. Metastases of human melanoma cell lines were clustered according to the expression profiles of genes CTCF, FBLIM1, HSPB1, NDRG2, NSD1, SERPINE1, SRC and VDR. Heatmaps were generated by unsupervised hierarchical clustering using the Pearson correlation as metric distance and average-linkage as algorithm as well. The saturation of either color (scale from green to red) reflects the magnitude of the difference on gene expression level. (B) Despite the molecular heterogenety observed in melanoma cells, relevance networks pointed out gene interactions commonly observed among the metastases examined, such as NDRG2/NSD1, VDR/NSD1, SRC/NSD1, CTCF/SERPINE1, HSPB1/SERPINE1 and FBLIM1/SERPINE1. FM305: human primary melanocytes from neonatal foreskin; Mel-2: right supraclavicular lymph node metastasis; Mel-3: counterpart of Mel-2 after the re-occurrence of the disease; Mel-11: brain metastasis; Mel-14: axillary lymph node metastasis, and Mel-33: inguinal lymph node metastasis. doi:10.1371/journal.pone.0044800.g007 (Figure 6B). Integrating the regulatory information can support positive or negative control of gene expression through synergism and antagonism. Therefore, a major effort needs to be done to find multiple regulatory signals, including epigenetic complexes, differentially deregulated at several phases of melanoma progres- sion. It could help find drugs that preferentially target cancer cells by exploring the effects of 5AzaCdR and/or TSA treatment and molecular heterogeneity in melanoma prevention. To summing up, the current study demonstrates the utility of our murine melanoma progression model to successfully identify PLOS ONE | www.plosone.org 14 September 2012 | Volume 7 | Issue 9 | e44800