Abstract 2398: S100P/RAGE signaling activates AP1 and NF-kB in miR-21/RECK regulation

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL The receptor for advanced glycation end-products (RAGE) plays a role in different pathological diseases including cancer. Several ligands activate RAGE, among them are AGEs (advance glycation end-products), HMGB1 (amphoterin), amyloid-α peptide, and the S100 Ca2+ binding family. Activation of RAGE by S100P stimulates many cell processes in cancer mediated by AP1, NF-kB and ERK1/2. Recently, these transcription factors were shown to induce expression of the oncogene, miR-21. Our data show that S100P over-expression in LS174T and SW480 colon cancer cells induces miR-21 expression. It is well known that S100P has an intracellular and an extracellular function when it interacts with Ezrin and RAGE respectively. To decipher if the extracellular function of S100P mediated by its interaction with RAGE induces miR-21, we treated SW480 normally expressing RAGE and not S100P with exogenous human recombinant (hr)-S100P. These results show that S100P/RAGE signaling induces miR-21 expression. To determine if the induction of miR-21 by S100P/RAGE signaling is mediated by AP1 and NF-kB, we performed luciferase studies with wild type, and mutated AP1 and NF-kB pri-miR-21 promoter constructs in cells expressing only the RAGE receptor. These data show that S100P/RAGE signaling mediates miR-21 induction by the activation of AP1 and NF-kB. Additionally, LS174T cells expressing RAGE and S100P rendered similar results when they ectopically over-express S100P. However, ectopic S100P expression in SW480 cells induced miR-21 independent of AP1 and NF-kB. These results suggest that S100P has another mechanism of regulating miR-21. Our previous data indicated that over-expression of S100P down regulates the reversion-inducing cysteine-rich protein with Kazal motifs (RECK). RECK is an anti metastatic gene, inhibitor of metalloproteinases and a target of miR-21. Our data shows that RAGE expressing cells treated with exogenous hr-S100P down regulate RECK expression, suggesting that miR-21 induction by S100P/RAGE signaling represses RECK. To determine if there is a correlation in expression levels of miR-21 with RECK, RAGE, and S100P, we used the combined method of in situ hybridization (ISH) and immunohistochemical (IHC) techniques on human colorectal cancer tissues. We found that there are three groups of cells in the malignant epithelium as well as in the surrounding tissue. One group of cells expresses high levels of miR-21, another group expresses high levels of RECK while the third group expresses both. Together, these data show that S100P/RAGE regulates miR-21/RECK expression mediated by AP1 and NF-kB and suggest that in cancer this signaling pathway remodels the extracellular matrix by the activation of metalloproteinases inducing epithelial mesenchymal transition to allow cell migration/invasion in colon cancer progression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2398. doi:1538-7445.AM2012-2398