Abstract B26: MiR-200 is involved in anti-invasive activity of sulindac in colon cancer

The chemopreventive benefits of nonsteroidal anti-inflammatory drugs (NSAIDs) are documented in various human cancers by numerous pre-clinical and clinical studies. However, the mechanisms accounting for NSAIDs9 anticancer activity have not been well understood, given the controversial findings when determining the key role of cyclooxygenase 2 (COX-2) inhibition in the action. MicroRNA is a set of non-coding small RNA molecules showing the “master” role in regulation of human coding gene expression. We are interested in studying if microRNA is able to address the underlying mechanism of NSAIDs9 anticancer activity. MiR-200 is a tumor suppressor microRNA and is well-known for its inhibitory effect on the epithelial-mesenchymal transition (EMT). Our previous study reported that the NSAID, sulidac sulfide (SS) can inhibit breast and colon tumor cell motility through a distinct mechanism from the known suppressive activity on tumor cell growth through COX-2 inhibition. In this study, we aim to study if miR-200 is involved in this underlying mechanism. By using human colon tumor cell lines, HCT116 and LIM2405, as the research models, we found that SS treatment could ultimately suppress the tumor cell invasion, while miR-200 was upregulated in parallel. When examining the expression levels of a panel of EMT related genes, we found the E-cadherin was upregulated but snail was downregulated inversely. E-cadherin was reported to be regulated by snail through the transcriptional repression; however, our results did not support the direct control of snail on E-cadherin in the colon tumor cells with miR-200 expression. When snail and miR-200 were forced to be overexpressed in HCT116 cells, E-cadherin was upregulated; when snail was knocked down by siRNAs in miR-200 overexpressed cells, E-cadherin maintained the static expression. These results suggest that the regulation of snail on E-cadherin in colon cancer cells may depend on miR-200 expression. To further support this hypothesis, we studied the interaction between snail and miR-200. The bioinformatics analysis suggested that several E-boxes on miR-200 gene promoter could serve as the binding sites of snail. By employing the chromatin immunoprecipitation (ChIP) and luciferase assays, we demonstrated that snail could directly bind to miR-200 promoter and regulate its expression at the transcriptional level. Our previous study showed that blockade NF-κB signaling is involved in SS inhibition of colon tumor cell motility. Given that snail was also reported to be regulated by NF-κB through the transcriptional modulation, these data suggest the NF-κB-snail-miR-200-E-cadherin axis may account for a novel mechanism to address the anti-metastatic activity of sulindac in colon cancer. Potentially, our results will provide insights into development of novel drugs in treatment of cancer patients with advanced diseases. This study is supported by the NIH/NCI R01 Grant (1R01CA192395) and the American Cancer Society Research Scholar Grant (RSG-13-265-01-RMC). Citation Format: Hong Chang, Xiangling Feng, Ruixia Ma, Yaguang Xi. MiR-200 is involved in anti-invasive activity of sulindac in colon cancer. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Cancer Cell Cycle - Tumor Progression and Therapeutic Response; Feb 28-Mar 2, 2016; Orlando, FL. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(11_Suppl):Abstract nr B26.