Abstract 1837: Exosomal non-coding RNAs as mediators for cell-cell communications .

Abstract Introduction: Exosomes are 30-100nm membrane vesicles of endocytic origin containing proteins, mRNAs, microRNAs and lincRNAs. MicroRNAs are small and lincRNAs are large intergenic non-coding RNAs. They are emerging as key regulators of diverse cellular processes including cancer. In this study, we investigated the exosome-mediated transfer of microRNAs and lincRNAs, regulation and functional significance in breast cancer. Approach: Exosomes were isolated by ultracentrifugation and stained with PKH26 dye for cellular uptake in different cells by confocal microscopy. This uptake was also shown by exosome isolated from stable 293T cell line overexpressing the pCDH-CD63-GFP fusion protein. To determine the effect of nSMase2 on exosome secretion, stable cell lines were established with smpd3 gene. Levels of microRNAs and lincRNAs secreted in media were determined by real time PCR and their function validated through western blot and cell invasion. Results: We first showed that exosomes can be transferred among different cell lines through direct uptake. We found that miR-10b is highly expressed in metastatic breast cancer MDA-MB-231 cells as compared to non-metastatic breast cells. Also, nSMase2 promoted the exosome-mediated miR-10b secretion whereas ceramide inhibitor suppressed this secretion. Importantly, western blot revealed that upon uptake, miR-10b can still reduce the protein level of its target genes. We also found lincRNA 21A and BC200 to be secreted through exosome in cell type dependent manner with functional significance. Conclusion: We found that the exosomes secreted from cancer cells containing microRNA and lincRNA can be taken up by other cells and have functional role in the recipient cells suggesting the importance of exosome-mediated RNA transfer in tumor microenvironment. Citation Format: Ramesh Singh, Yin-Yuan Mo. Exosomal non-coding RNAs as mediators for cell-cell communications . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1837. doi:10.1158/1538-7445.AM2013-1837