Identification of differentially expressed genes in nasopharyngeal carcinoma by means of the Atlas human cancer cDNA expression array

Pm pose: To investigate genes of critical areas, including cell cycle/growth control, apoptosis. oncogene/tumor suppressors and growth factor/cytokines, that are differentially expressed in nasopharyngeal carcinoma. Methods: The Human Cancer cDNA Atlas. which contains 588 genes relating to tumor biology, was used to screen normal nasopharyngeal tissue, nasopharyngeal cancer (NPC). The reverse transcription/polymerase chain reaction was used to confirm the expression pattern of some genes identified by Atlas hybridization. Results: The differentially expressed cell cycle/growth control regulators in NPC showed a stronger tendency toward cell proliferation with the upregulation of cyclin D1, cyclin D2 etc. The expression pattern of apoptosis-related genes demonstrated the upregulation of both anti-apoptotic factors such as the BCL-2-related protein A1, TRAF3. the inhibitor of apoptosis protein A1 (IAP1) and apoptotic pathway elements such as FasiApo-1, Apo-2 ligand etc. Among oncogenes/tumor suppressors, MDM2, STAT1 and STAT2 were found to be up-regulated in NPC. The expression profile of growth factors/cytokines showed the up-regulation of many growth-enhancing factors such as EGR1, tumor-derived growth factor 1, platelet-derived growth factor A chain etc, as well as Th1-type cytokines e.g. interleukin-1 beta and interferons. A smaller number of genes were down-regulated in nasopharyngeal cancer, such as those encoding ERK1, Raf, secreted apoptosis-related protein 1, CD27BP, transforming growth factor beta 2, pre-B-cell-stimulating factor homologue etc. Conclusion: The consistent tendency toward cell proliferation, the possibility of a stronger anti-apoptotic force that operates on the normal apoptotic pathway, or the autocrine or paracrine growth factors may account for the development of NPC. Some genes are reported for the first time to have changed expression in nasopharyngeal carcinoma. The simple, quick, and high-throughput method of profiling gene expression by cDNA array hybridization provides us with a quick overview of key factors that may be involved in NPC, and may identify genes suitable for further study of carcinogenesis mechanism or targets for possible molecular diagnosis or therapy.