Suprabasin as a novel tumor endothelial cell marker

Recent studies have reported that stromal cells contribute to tumor progression. We previously demonstrated that tumor endothelial cells (TEC) characteristics were different from those of normal endothelial cells (NEC). Furthermore, we performed gene profile analysis in TEC and NEC, revealing that suprabasin (SBSN) was upregulated in TEC compared with NEC. However, its role in TEC is still unknown. Here we showed that SBSN expression was higher in isolated human and mouse TEC than in NEC. SBSN knockdown inhibited the migration and tube formation ability of TEC. We also showed that the AKT pathway was a downstream factor of SBSN. These findings suggest that SBSN is involved in the angiogenic potential of TEC and may be a novel TEC marker. We showed that Suprabasin (SBSN) was highly expressed in human TECs isolated from colon cancer and renal cell carcinoma (RCC). Immunostaining of these two human tumor blood vessels also revealed strong SBSN expression in vivo. To analyze the function of SBSN, TECs were isolated from human tumor xenografts in nude mice. We also found that, SBSN contributed to proangiogenic phenotype of TEC by promoting migration and tube formation through the activation of AKT. This is the first report about the expression and function of SBSN in TEC. This study suggests that SBSN is a novel target for anti-angiogenic therapy, which is specific for tumor blood vessels.