Abstract B19: Tumor-suppressive activities associated to MIR10A-5p expression in developmental sarcomas

Ewing sarcoma (ES) and alveolar rhabdomyosarcoma (ARMS) are pediatric sarcomas characterized by tumor-specific translocations. Besides acting as a direct modulator of transcription, fusion proteins appear to exert its oncogenic functions by epigenetic modifications on the transcriptome. Therefore, the identification of specific DNA methylation markers would be helpful for understanding their pathogenetic mechanism as well as for developing new therapeutic strategies. By using the Illumina Infinium HumanMethylation450 we have analyzed the methylome of ES and ARMS tumors and cell lines. ES and ARMS samples showed, among other epigenetic alterations, differential hypermethylation in the promoter of MIR10A-5p, thus suggesting an inhibition of its expression. Expression of MIR10A-5p is effectively low in ES and ARMS cell lines and patient samples and the treatment with the epigenetic modifier 5-aza restores its expression. MIR10A-5p stable overexpression in two ES (A673 and TC252) and two ARMS (Rh4 and RMS13) cell lines reduces proliferation, diminishes clonogenic growth, and decreases cellular migration. Cell death induced by MIR10A-5p reintroduction is only achieved in the p53wt ES cell line TC252. Proteomic profile of A673 MIR10A-5p cells is altered as assessed by iTRAQ. Protein kinase CRKL is one of the proteins downregulated due to MIR10A-5p reintroduction. Indeed, CRKL expression is also reduced in the other three MIR10A-5p stable overexpression models. Doxycycline-induced silencing of CRKL in ARMS cell line Rh30 provokes cell growth reduction in vitro and in vivo, G0/G1 arrest, and a decrease in the clonogenic capacity (Yeung CL et al., 2013). Interestingly, the migratory ability of Rh30 and A673 CRKL-silenced cells is also impaired. Thus, our results uncover MIR10A-5p as a putative tumor suppressor in ES and ARMS, suggesting a link between MIR10A-5p and CRKL. Further characterization of the oncogenic role of CRKL and the molecular mechanisms associated to MIR10A-5p tumor-suppressor activities in ES and ARMS is ongoing. Citation Format: David Herrero-Martin, Santiago Rello-Varona, Silvia Garcia-Monclus, Juan Huertas-Martinez, Olga Almacellas-Rabaiget, Lee J. Helman, Oscar M. Tirado. Tumor-suppressive activities associated to MIR10A-5p expression in developmental sarcomas [abstract]. In: Proceedings of the AACR Conference on Advances in Sarcomas: From Basic Science to Clinical Translation; May 16-19, 2017; Philadelphia, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(2_Suppl):Abstract nr B19.