Abstract 955: Inhibition of SEC24D decreases exosome release of the tumor suppressor miR-605 in renal cell carcinoma

Background: MicroRNA 605 (miR-605) has been recently reported as a putative tumor suppressor and its overexpression decreases tumor cell proliferation, migration and clonogenicity. To date, the role of miR-605 in renal cell carcinoma (RCC) has not been investigated. We recently showed the decrease of circulating miR-605 in serum of clear cell renal cell carcinoma (ccRCC) patients who responded to the treatment with the histone deacetylase (HDAC) inhibitor vorinostat, and the VEGF blocker bevacizumab. The current study was designed to investigate the expression of miR-605 and understand the mechanism(s) responsible the extracellular release of miR-605 using RCC cells. Methods: 786-0 cells were treated with and without vorinostat for 24h and condition media were collected, briefly centrifuged to settle the cells and debris, and processed to isolate exosomes using the ExoQuick exosome isolation kit (Systems Biology, CA). Purified exosomes and 786-0 cells were used to isolate RNA and further prepared cDNA to utilize for quantitative RT-PCR analysis. Expression of miR-605 in exosomes and cells was determined by Quantitative RT-PCR using TaqMan MicroRNA Assays with miR-605 primers obtained from Applied Biosystems, NY. To determine the role of secretory protein 24 family member D (SEC24D), a catalytic component of coat protein complex (COPII) involved in the secretory pathway, 786-0 cells treated with vorinostat were used to determine SEC24D expression by QRT-PCR and Western blot analysis. TCGA data was used to determine correlation of SEC24D expression clear cell renal cell carcinoma patients’ survival. Results: Vorinostat treatment resulted in a significant decrease of miR-605 expression in exosomes and increase (100 fold) of intracellular expression. Furthermore, the increased intracellular miR-605 was associated with the inhibition of SEC24D mRNA and protein expression in 786-0 cells treated with vorinostat. Cancer Genomic data analysis of c-Bioportal from MSKCC of TCGA revealed the overall poor survival of ccRCC patients with alteration of SEC24D. Conclusion: Taken together, our preliminary data suggest that the HDAC inhibitor vorinostat inhibits SEC24D and exosome mediated extracellular secretion of miR-605 in RCC cells. These results suggest that vorinostat treatment retained intracellular miR-605 that target genes involved in cell survival and proliferation in RCC. Further studies will evaluate circulating miR-605 as a predictive biomarker to determine the efficacy of vorinostat in ongoing trials with RCC patients. Citation Format: Sreenivasulu Chintala, Remi Adelaiye-Ogala, Ashley Orillion, Sreevani Arisa, May Elbanna, Roberto Pili. Inhibition of SEC24D decreases exosome release of the tumor suppressor miR-605 in renal cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 955.