Circular RNAs in peripheral blood mononuclear cells are more stable than linear RNAs upon sample processing delay

Area of Science:

• Molecular Biology
• Genomics
• Biochemistry

Background:

• Circular RNAs (circRNAs) are a novel class of non-coding RNAs with a unique closed-loop structure.
• Blood circRNAs exhibit higher stability than linear mRNAs, positioning them as potential liquid biopsy biomarkers.
• The impact of sample processing delays on blood circRNA expression profiles is not well understood.

Purpose of the Study:

• To investigate the effects of prolonged sample processing delays on the expression profiles of circRNAs, mRNAs, and lncRNAs in peripheral blood mononuclear cells (PBMCs).
• To explore the mechanisms behind aberrant circRNA expression relative to their corresponding mRNA transcripts.
• To assess the stability of circRNAs as potential liquid biopsy biomarkers under delayed sample processing conditions.

Main Methods:

• Whole blood samples from three donors were collected and PBMCs were isolated at six different time points.
• RNA sequencing (RNA-seq) was employed to measure total RNA expression profiles.
• Differential expression analysis and alternative splicing (AS) event screening using rMATS-turbo and CIRI-AS were performed.

Main Results:

• Incubation at 4°C for up to 48 hours minimally affected circRNA expression.
• Extended incubation beyond 12 hours induced significant alterations in mRNA and lncRNA expression.
• Linear mRNA alternative splicing events were notably impacted by delays as short as 2 hours, while circRNAs showed less impact.

Conclusions:

• PBMC circRNAs demonstrate remarkable stability even with prolonged sample processing delays.
• The stability of circRNAs suggests their suitability as robust biomarkers for liquid biopsies.
• Delayed processing significantly impacts mRNA and lncRNA profiles, highlighting the advantage of using circRNAs.