Abstract 1486: Bladder cancer exosomes contain tumor-associated mRNA and long non-coding RNA and facilitate tumor progression
Authors: Olsen Jayme , Flax Jonathan D. , Messing Edward M. , Beckham Carla J. 
Published: May 2015

INTRODUCTION: Exosomes are 30-100nM membrane bound vesicles that contain protein, miRNA, mRNA, long non-coding (lnc)RNA and can facilitate tumor progression. Recently, we showed that exosomes from bladder cancer (BC) cell lines and urine of BC patients promote angiogenesis, migration and invasion (submitted). Given the complexity of exosomes, investigation of how each class of biomolecule affects tumor biology is critical. The lncRNAs HOTAIR and MALAT1 have been shown to mediate invasiveness in several tumors including BC. Knockdown of MALAT1 or HOTAIR reduced invasion, growth and motility. To this end, we asked if BC exosomes contain or affect the levels of tumor-associated lncRNAs in cells exposed to exosomes.

METHODS: A commercial array was used to identify mRNA and lncRNAs in exosomes from BC cell lines. qRT-PCR and sequencing confirmed full-length candidate RNAs in exosomes from cell lines and patients. lncRNA and mRNA levels in cells treated with BC exosomes were quantitated by qRT-PCR. Tumor progression of exosome treated cells was evaluated in vitro by standard scratch migration and trans-well invasion assays. HOTAIR was knocked down with shRNA-HOTAIR.

Results: Over 2000 transcripts were identified in BC exosomes. Candidate transcripts were selected based on abundance or known roles in tumor progression and were confirmed by qRT-PCR in exosomes of high-grade BC cell lines: TCC-SUP and T24. Some transcripts were more abundant in exosomes vs. corresponding cell lysates. TCC-SUP exosomes were differentially enriched in some transcripts vs. T24 exosomes. Many of the same lncRNAs and mRNAs identified in cell lines, were enriched in urinary exosomes from pT2+ BC patients vs. controls. Exosomes from TCC-SUP, T24 and patients facilitated increased invasion and migration of recipient 5637 BC cells. Importantly, these tumor progression phenotypes correlated with increased levels of lncRNAs including HOTAIR and MALAT1 in recipient 5637cells. Critically, downstream targets of HOTAIR activation; laminins, SNAIL and ABL2 involved in epithelial to mesenchymal transition, were elevated in recipient 5637 cells. In addition, knockdown of HOTAIR resulted in alterations in target gene expression.Conclusions: BC exosomes from cells lines and urine of pT2+ BC patients contain tumor-associated mRNA and lncRNAs including MALAT1 and HOTAIR and facilitate migration and invasion. Increased levels of several tumor-associated transcripts were observed in exosome treated cells, suggesting that exosomes may deliver and or induce the expression of mRNA and lncRNAs to promote tumor progression.

Citation Format: Jayme Olsen, Jonathan D. Flax, Edward M. Messing, Carla J. Beckham. Bladder cancer exosomes contain tumor-associated mRNA and long non-coding RNA and facilitate tumor progression. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1486. doi:10.1158/1538-7445.AM2014-1486