Forty-five primary malignant melanomas, 18 benign skin nevi, and 7 normal skin tissues were hybridized on an Affymetrix Hu133A microarray (Santa Clara, CA) containing 22,000 probe sets. In this study, we report the gene expression profiling of an extensive set of clinically relevant tissue samples. ( 15), comparison of gene expression profiles of a few melanoma and normal melanocyte cell lines led to the identification of differentially expressed genes and pathways modulated in melanoma. These researchers identified several genes that might be associated with aggressive tumor behavior. ( 14) did gene expression profiling of malignant melanoma, using a microarray containing probes for 8,150 cDNAs. Studies have resulted in the identification of genes differentially expressed in benign and malignant lesions ( 12), as well as genes that might be of prognostic value ( 13). High-density microarrays have been applied to simultaneously monitor the expression of thousands of genes in biological samples.
The identification of novel melanoma-specific markers remains one of the key objectives in melanoma research. proposed a multimarker panel, including cancer-specific markers, for RT-PCR assay in order to increase assay specificity ( 11). Considering that benign nevi are not rare events in the melanoma sentinel lymph nodes, the current RT-PCR assays are not clinically useful for the diagnostics of melanoma micrometastasis. In fact, they cause false-positive results in the presence of benign capsular nevi ( 9– 11). However, these genes are not specific to tumor cells and cannot be used to discriminate between benign and malignant tissue. Many studies, when using well-characterized melanocyte-specific markers, such as tyrosinase and MART-1, have shown the presence of these gene transcripts in the lymph node, which were negative when using routine histologic and immunohistochemical methods ( 7, 8). Reverse transcription-PCR (RT-PCR) analysis has recently been proposed for a more sensitive detection of melanoma cells in lymph nodes. Nevertheless, even with enhanced by immunohistochemistry, histologic analysis is limited by the ability of light microscopy to recognize the tumor cells. Introduction of the sentinel lymph nodes technique ( 4) has increased the sensitivity of melanoma micrometastasis detection compared to H&E staining alone ( 5, 6). Therefore, regional lymph node status becomes the most significant prognostic factor for a melanoma patient's survival. Although the prognosis for early local melanoma is favorable with 5-year overall survival of >90%, regional lymph node involvement decreases the overall survival rate by 10% to 46% ( 3). The incidence of melanoma continues to increase faster than that of any other malignancy ( 2). The performance of the markers was compared with conventional melanoma markers such as tyrosinase, gp100, and MART1.Ĭonclusion: Our study systematically identified novel melanoma-specific genes and showed the feasibility of using a combination of PLAB and L1CAM in a reverse transcription-PCR assay to differentiate clinically relevant samples containing benign or malignant melanocytes.Ĭutaneous malignant melanoma is a serious healthcare problem with >55,100 new cases anticipated in 2004 in the U.S., with a mortality rate of about 14.5% ( 1). Differential gene expression of two melanoma-specific genes, PLAB and L1CAM, were tested by a one-step quantitative reverse transcription-PCR assay on primary malignant melanoma, benign nevi, and normal skin samples, as well as on malignant melanoma lymph node metastasis and melanoma-free lymph nodes. Novel genes associated with malignant melanoma were identified. Results: Hierarchical clustering revealed a distinct separation of the melanoma samples from the benign and normal specimens. The identification of melanoma-specific deregulated genes could provide molecular markers for lymph node staging assays and further insight into melanoma tumorigenesis.Įxperimental Design: Total RNA isolated from 45 primary melanoma, 18 benign skin nevi, and 7 normal skin tissue specimens were analyzed on an Affymetrix Hu133A microarray containing 22,000 probe sets. Purpose: Cutaneous melanoma is a common, aggressive cancer with increasing incidence.
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