Profiling Of Endogenous Circular Rna Molecules In Formalin-Fixed Paraffin-Embedded Tissues From Patients With B-Cell Malignancies Using An Enzyme-Free Digital Counting Method

Circular RNAs (circRNAs) are covalently closed endogenous RNA molecules with tissue- and disease specific expression patterns, which have potential as diagnostic and prognostic biomarkers in cancer. The landscape of circRNA expression has not been characterized in B-cell malignancies, and current methods for circRNA quantification have several limitations that prevent development of clinically applicable assays. Based on high-throughput RNA sequencing (RNA-seq) data, we designed assays for analyzing 52 unique circRNAs simultaneously, using a digital, enzyme-free technology termed NanoString, in cell lines and paired fresh frozen and formalin-fixed, paraffin-embedded (FFPE) patient samples (including mantle cell lymphoma, multiple myeloma, follicular lymphoma, diffuse large B-cell lymphoma, Burkitt lymphoma and chronic lymphocytic leukemia). The data obtained using NanoString were compared to RNA-seq and reverse transcription-qPCR (RT-qPCR) data obtained on the same samples. RNA-seq profiling revealed a high expression of circRNAs in B-cell malignancies and the NanoString circRNA expression profiles were able to distinguish different B-cell malignancies. We detected circRNAs known to be deregulated in other cancers, including ciRS-7, circHIPK3 circCCDC66, circCDYL, circZKSCAN1 and circFBXW7, and identified a novel circRNA from the IKZF3 oncogene. NanoString data were more reproducible and quantitatively accurate than RNA-seq data and the technology works in particular well for low quality RNA samples. Together, we demonstrate that the NanoString technology enables specific, sensitive and accurate quantification of circRNAs in FFPE samples and provide a map of circRNA expression in B-cell malignancies. Citation Format: Lasse Sommer Kristensen, Mette Dahl, Maria S. Andersen, Iben Daugaard, Thomas B. Hansen, Kirsten Gronbaek, Jorgen Kjems. Profiling of endogenous circular RNA molecules in formalin-fixed paraffin-embedded tissues from patients with B-cell malignancies using an enzyme-free digital counting method [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-394.