Abstract 197: miR-130b targets Arhgap1 increasing Cdc42 activity and metastic potential in Ewing sarcoma cells

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Osteosarcoma (OS) and Ewing's sarcoma (EWS) are the most common bone tumors in the pediatric population. While significant progress has been made with towards increasing patient outcomes, our success in eradicating these two malignances is significantly less than most other pediatric malignancies. One reason for continued treatment failure is due to high risk disease states such as the presence of metastatic lesions. Metastasis is of the utmost clinical relevance as it accounts for more than 90% of solid tumor deaths. Improvements in treatment regimens have been stagnant over the past 20-30 years most likely due to our lack of understanding their molecular pathogenesis. Overall survival rates are approximately 65-70% for localized disease and less than 20% for aggressive, disseminated states. Thus, the clinical need to understand high risk disease, such as metastasis is significant in order to develop novel therapeutics. miRNAs are highly conserved short 18-22 single stranded non-coding RNAs that have the ability to repress target translation and affect key cell signaling pathways often deregulated in cancer. Recently, miRNAs have been implicated in numerous cancers; however the functional role of miRNAs in sarcomas is limited. In order to identify novel alterations in miRNAs, we have utilized our analysis of microRNA expression from localized and metastatic tumors derived from novel genetically engineered mouse models of osteosarcoma. Among the miRNAs most significantly dysregulated, miR-130b was shown to be significantly upregulated in the metastatic lesions. Furthermore, it has been shown that miR-130b is overexpressed in OS and EWS patient samples, and this event is significantly associated with poor patient outcome in the latter sarcoma. Furthermore, we have verified miR-130b overexpression in both mouse and human sarcoma cell lines and in metastatic EWS tumor samples obtained from Texas Children's Hospital. Functional analysis shows overexpression of miR-130b increases migration and invasion in vitro. In order to identify novel targets of miR-130b contributing to metastasis, we performed gene expression analysis. We identified Cdc42GAP as a novel target of miR-130b. Cdc42GAP is a negative regulator of Cdc42 which hydrolyzes the active GTPase. ELISA analysis of Cdc42 activity reveals that Cdc42 activity is increased with overexpression of miR-130b.Further microarray and pathway analysis suggest a mechanism by which activation of Cdc42 leads to positive regulation of the MAPK cascade. Subsequent western blot analysis reveals that overexpression of miR-130b leads to the activation of SAPK/JNK and subsequent phosphorylation of c-JUN suggesting activation of AP-1 transcription factor. Taken together, these findings suggest that overexpression of miR-130b promotes sarcoma cell migration and invasion through targeting of Cdc42GAP and modulation of the Cdc42 and SAPK pathways. Citation Format: Laura Satterfield, Lyazat Kurenbekova, Ryan Shuck, Lawrence Donehower, Jason Yustein. miR-130b targets Arhgap1 increasing Cdc42 activity and metastic potential in Ewing sarcoma cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 197. doi:10.1158/1538-7445.AM2015-197