Identification of genes down-regulated during melanoma progression: a cDNA array study

In order to identify genes relevant for melanoma development, we carried out cDNA array experiments employing an in vitro model of human melanoma progression, consisting of two cell lines: one, LP, derived from a primary melanoma and the other, LM, from its metastatic supraclavicular lymph node. Basic cDNA array data identified 26 genes as down-regulated in the LM cell line. Northern blot analysis confirmed an effective transcriptional down-regulation for five out of 13 genes analyzed. The products of these five genes belong to different functional protein types, such as transcription and translation regulators (Edg-2, eIF-3 p110, and RNPL/RBM3), extracellular communicators (PRSS11) and members of the major histocompatibility complex (beta2-microglobulin). Some previously described differences in expression patterns, such as loss of HLA I, were confirmed by our array data. In addition, we identified and validated for the first time the reduced expression level of several genes during melanoma progression. In particular, reduced Edg-2 gene product expression was also confirmed in a group of 50 primary melanomas and unrelated metastases. In conclusion, comparative hybridization by means of cDNA arrays assisted in identifying a series of novel progression-associated changes in gene expression, confirming, at the same time, a number of previously described results.