Targeting S100P Inhibits Colon Cancer Growth and Metastasis by Lentivirus-Mediated RNA Interference and Proteomic Analysis

S100P was recently found to be overexpressed in a variety of cancers and is considered a potential target for cancer therapy, but the functional role or mechanism of action of S100P in colon cancer is not fully understood. In the present study, we knocked down the gene expression of S100P in colon cancer cells using lentivirus-mediated RNA interference. This step resulted in significant inhibition of cancer cell growth, migration and invasion in vitro and tumor growth and liver metastasis in vivo. Moreover, S100P downstream target proteins were identified by proteomic analysis in colon cancer DLD-1 cells with deletion of S100P Knockdown of S100P led to downregulation of thioredoxin 1 and beta-tubulin and upregulation of Rho guanosine diphosphate (GDP) dissociation inhibitor alpha (RhoGDIA), all potential therapeutic targets in cancer. Taken together, these findings suggest that S100P plays an important role in colon tumorigenesis and metastasis, and the comprehensive and comparative analyses of proteins associated with S100P could contribute to understanding the downstream signal cascade of S100P leading to tumorigenesis and metastasis. (C) 2011 The Feinstein Institute for Medical Research, www.feinsteininstitute.org