One-Pot Endonucleolytically Exponentiated Rolling Circle Amplification by CRISPR-Cas12a Affords Sensitive, Expedited Isothermal Detection of MicroRNAs

MicroRNAs (miRNAs) are a class of short non-coding RNAs that play essential roles in gene expression regulation. While miRNAs offer a promising source for developing potent cancer biomarkers, the progress towards clinical utilities remains largely limited, due in part to the long-standing challenge in sensitive, specific, and robust detection of miRNAs in human biofluids. Emerging next-generation molecular technologies, such as the CRISPR-based methods, promise to transform nucleic acid testing. The prevailing strategy used in existing CRISPR-based methods is to hyphenate two separate reactions for pre-amplification, e.g., rolling circle amplification (RCA), and amplicon detection by Cas12a/13a trans-cleavage in tandem. Thus, existing CRISPR-based miRNA assays require multiple manual steps and lack the analytical performance of the gold standard, RT-qPCR. Radically deviating from the existing strategies, we developed a one-step, one-pot isothermal miRNA assay termed "Endonucleolytically eXponenTiated Rolling circle Amplification with the dual-functional CRISPR-Cas12a" (EXTRA-CRISPR) to afford RT-PCR-like performance for miRNA detection. We demonstrated the superior analytical performance of our EXTRA-CRISPR assay to detect miRNAs (miR-21, miR-196a, miR-451a, and miR-1246) in plasma extracellular vesicles, which allowed us to define a potent EV miRNA signature for detection of pancreatic cancer. The analytical and diagnostic performance of our one-pot assay were shown to be comparable with that of the commercial RT-qPCR assays, while greatly simplifying and expediting the analysis workflow. Therefore, we envision that our technology provides a promising tool to advance miRNA analysis and clinical marker development for liquid biopsy-based cancer diagnosis and prognosis.