Ns, also as PKCη Molecular Weight autophagy-related proteins such as LC3 and p62, within the EV fraction of the culture media. We also identified that inhibitor treatment facilitates nNOS Accession secretion of EVs distinct from exosomes in size, and that these EVs are involved in secretion of ubiquitinated proteins. Interestingly, evaluation of knockout cells deficient for autophagy-related proteins revealed that the elements within the initiation step of autophagy are necessary for EVmediated secretion of ubiquitinated proteins.ISEV2019 ABSTRACT BOOKSummary/Conclusion: These benefits indicate that autophagy impairment promotes secretion of ubiquitinated proteins through EVs. Our data offer the mechanistic link between the autophagy/lysosome pathway and vesicle secretion. We propose that cells might make use of the EV-mediated secretion as an option pathway to retain protein homeostasis when cellular proteostasis machinery is functionally impaired. Funding: This perform was supported by JST; by KAKENHI (18H02585); by The Asahi Grass Foundation and the Tokyo Biochemical Investigation Foundation.miRNAs, four miRNAs altered the EV secretion in both cell lines, HCT116 and A549. Summary/Conclusion: Some of these target genes have reported as endosomal pathway associated protein and shown the up-regulation in cancer cells. These findings recommend that the identification of target genes of these miRNAs supplies the new insight into the cancer cell communication using the microenvironmental cells, which leads to a promising therapeutic method against cancer progression.PF07.04 PF07.Identifying the miRNAs related with EV Secretion from cancer cell lines Tomofumi Yamamotoa, Nobuyoshi Kosakab, Fumihiko Urabea, Yutaka Hattoric and Takahiro Ochiyab Division of Molecular and Cellular Medicine, National Cancer Center Research Institute, Tokyo, Japan; bDepartment of Molecular and Cellular Medicine, Institute of Healthcare Science, Tokyo Healthcare University, Shinjyuku-ku, Japan; cClinical Physiology and Therapeutics, Keio University Faculty of Pharmacy, Tokyo, JapanaRas Tumour microvesicles biogenesis and signalling in drosophila Vakil Ahmad, Carson Broeker, Kayla Calandro and Yves Chiswili. Chabu University of Missouri, Columbia, USAIntroduction: Extracellular vesicles (EVs) derived from cancer cells contribute to their surrounding microenvironmental cells for their benefit. Our group has previously shown that inhibiting the EVs production attenuated the angiogenesis in the tumour, resulting in the suppression of metastasis. Hence, understanding the mechanisms of EV secretion may contribute for the regulation of EVmediated cancer progression. Having said that, the precise mechanism of EV secretion in cancer cells remains unclear. The purpose of this study should be to elucidate the unknown mechanisms of EV secretion in cancer cells. To reveal this, microRNAs (miRNAs), which regulate numerous genes, are employed. Solutions: To recognize the EV secretion related miRNAs, miRNA-based screening technique was established. Combined with ExoScreen, which is ultra-sensitive detection method of EV by measuring surface protein of EVs, including CD9 and CD63, miRNAbased screening was performed in colorectal cancer cell line, HCT116, and lung cancer cell line, A549. The results with the screening were confirmed by the nanoparticle tracking evaluation. Candidate genes of those miRNAs have been selected by in silico analysis. Outcomes: In the initial 1728 miRNAs, we identified 13 miRNAs that are linked with EV secretion in each cell lines. Then, the target.