In addition to inflammation, microarray analyses have revealed changes in SEPP1 expression during development and following alterations in the differentiation state of extrahepatic cells. Elegant developmental studies have demonstrated SEPP1 ortholog spatiotemporal expression in both zebrafish (Thisse et al. 2003) and murine model systems (Lee et al. 2008). Increased expression has been observed in differentiating myeloid, pulmonary, and Sertoli cells (Tabuchi et al. 2005; Ghassabeh et al. 2006; Wade et al. 2006). Conversely, SEPP1 expression is decreased with neoplastic progression from normal tissue, to carcinoma, to metastatic disease in cells of prostate origin (Dhanasekaran et al. 2001). Evaluation of SEPP1 expression in the Oncomine database (Rhodes et al. 2004) also identifies decreased SEPP1 expression in melanoma, lung, and colon cancer compared to normal tissue suggesting that decreased SEPP1 expression may be a common feature of malignancies. Indeed, work in colorectal cancer suggests that specific selenoenzymes are reduced, indicating that changes in SEPP1 is not a general alteration in nutrition or decreased selenium (Al-Taie et al. 2004).
