Microarray analysis shows multiple signaling pathways are involved in basal cell carcinoma growth

BACKGROUND: Basal cell carcinoma (BCC) is the most common form of human cancer. Though the genetic mutation and subsequent aberrant signaling role of the Hedgehog pathway in BCC development is understood, little is known about the downstream genetic mechanisms underlying BCC growth. The characterization of molecular events would improve our understanding of carcinogenesis and may define new therapeutic intervention opportunities. OBJECTIVE: To identify differential gene expression associated with tumorigenesis promotion and to define common signaling pathways significant in BCC survival and growth. METHODS: Microarray analysis, using a 21K expanded sequence verified cDNA set was performed on tissues obtained from previously untreated patients undergoing Mohs surgical resection (8 superficial BCC, 8 nodular BCC, 7 morphea form, 8 normal skin). Significantly differentially expressed genes were identified by analysis of microarray results in various data sets and subsequently screened for signaling pathway involvement. Selected genes were validated using real-time PCR analysis using an expanded set of 31 BCC samples. RESULTS: The global gene expression profiles in BCCs and normal skin were distinguishable by unpaired T test. 2429 genes were at least 1.5 fold differentially expressed between BCC (all morphological types) and normal skin (p < 0.01). Multiple singaling pathways were activated, but the hedgehog, WNT, MAPK and calcium signal transduction pathways predominated. CONCLUSION: Our findings may have important implications for understanding the pathogenesis of BCC and suggest targeting of the WNT and MAPK pathways with therapeutic intervention. Keywords: disease state analysis Human BCC and normal skin tissues were obtained from 31 patients in the Department of Dermatology and Skin Science, University of British Columbia with approval from the University Clinical Research Ethics Board. For microarray analysis, tissue samples were collected from different subtypes and normal controls as follows: nodular (8), Morphea form (7), Superficial (8) and microdissected normal skin epithelium (8). All of samples were taken from the facial area. Human Operon v.2.1 (21K) glass arrays were produced (based on human 70mers from Operon Biotechnologies Inc, Huntsville, AL) by the Microarray Facility of the Prostate Centre at Vancouver General Hospital, Vancouver, Canada [17, 18]. RNAs were amplified using the SenseAmp Plus kit (Genisphere Inc, Hatfield, PA). The calculated A 260/280 ratio was used to determine the appropriate amount of sense RNA for labeling. Total RNA from test samples and universal human reference RNA (Stratagene, Cedar Creek, TX) were differentially labeled with Cy5 and Cy3 respectively, with the 3DNA array detection 350 kit (Genisphere Inc, Hatfield, PA) and cohybridized to cDNA microarrays. Following overnight hybridization and washing, arrays were imaged using a ScanArray Express scanner (PerkinElmer, Boston, MA).