Abstract 1332: Extracted mRNA from frozen buffy coat samples shows promise for use in downstream sequencing analyses

Abstract

Abstract Frozen blood samples are routinely collected and stored in medical biobanks across the world, often for periods of several decades, and later used for medical research such as biomarker studies. Some common biomarker targets have included DNA alterations, protein or antibody levels or metabolomics. However, despite the potential importance of gene-expression alterations in circulating immune cells, transcriptional studies on blood samples from biobanks have been limited due to preanalytical technical difficulties of extracting high-quality RNA. In the absence of an RNA preservative, RNA degrades rapidly during the thawing process. Our aim was, therefore, to investigate the possibility of using biobanked blood samples for transcriptomics analyses. First, we used a CryoXtract CXT 350 to establish a protocol capable of isolating high-quality RNA from frozen core aliquots of buffy coat without thawing the entire sample tube. Then, we performed RNA sequencing on RNA extracted from 20 pre-diagnostic buffy coat samples from colorectal cancer patients and matched controls included in the population-based, prospective Northern Sweden Health and Disease Study (NSHDS). For all samples, two different library preparation methods were used (Illumina TruSeq Stranded mRNA poly-A selection and Illumina Stranded Total RNA with Ribo-Zero Globin). We obtained RNA yields of more than 1 µg from a majority of the NSHDS samples (mean=2.57 µg), and more than 92% of samples had RIN values of 6 or higher, indicating suitability for downstream analyses. Preliminary random forest analyses showed expected discriminatory ability between men and women based on data generated from each of the two library preparation methods. In conclusion, our newly established RNA extraction method enables extraction of RNA from frozen, biobanked buffy coat samples, collected in standard tubes, that is of sufficient quantity and quality for use in downstream whole-genome transcriptomic analyses, such as RNA sequencing. Citation Format: Erik Bovinder Ylitalo, Linda Vidman, Sophia Harlid, Bethany Van Guelpen. Extracted mRNA from frozen buffy coat samples shows promise for use in downstream sequencing analyses [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1332.