Analysis of the circular RNA transcriptome in endometrial cancer

Abstract

// Bei Jun Chen 1 , Frances L. Byrne 1 , Konii Takenaka 1 , Susan C. Modesitt 2 , Ellen M. Olzomer 1 , James D. Mills 3 , Rhonda Farrell 4 , Kyle L. Hoehn 1 and Michael Janitz 1, 5 1 School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia 2 Division of Gynecologic Oncology, Obstetrics and Gynecology Department, University of Virginia Health System, Charlottesville, VA, USA 3 Department of Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands 4 Gynecologic Oncology, Royal Hospital for Women, University of New South Wales, Sydney, NSW, Australia 5 Paul-Flechsig-Institute for Brain Research, University of Leipzig, Leipzig, Germany Correspondence to: Michael Janitz, email: m.janitz@unsw.edu.au Keywords: circRNAs; RNA-Seq; transcriptome; endometrial cancer; hotspot genes Received: October 20, 2017      Accepted: December 01, 2017      Published: December 20, 2017 ABSTRACT Circular RNAs (circRNAs) are a naturally occurring family of non-coding RNA that may regulate gene expression in mammals. circRNAs are more stable than messenger RNAs due to their resistance to RNA exonuclease. A growing body of evidence has shown that the expression of circRNAs is regulated during development in a tissue-specific manner. CircRNAs have been implicated in a number of cancers; however, their role in endometrial cancer (EC) is completely unknown. Here, we report the circular transcriptome specific for EC as determined by RNA sequencing. We found that the overall abundance of circRNAs is lower in EC than in normal endometrium. Further, there are numerous ‘hotspot’ genes from which circRNAs are transcribed that may account for alterations in circRNA expression between the normal and malignant endometrium. Most importantly, we have also identified circRNAs that are differentially expressed between malignant and normal endometrial tissue. The functional significance of these circRNAs in cancer remains to be determined, but they may serve as potential biomarkers for the diagnosis of EC or monitoring of EC progression.