RESUMO
BACKGROUND: The clustered regulatory interspaced short palindromic repeats (CRISPR)-Cas13a system has strong potential for highly sensitive detection of exogenous sequences. The detection of KRASG12 point mutations with low allele frequencies may prove powerful for the formal diagnosis of pancreatic ductal adenocarcinoma (PDAC). RESULTS: We implemented preamplification of KRAS alleles (wild-type and mutant) to reveal the presence of mutant KRAS with CRISPR-Cas13a. The discrimination of KRASG12D from KRASWT was poor for the generic KRAS preamplification templates and depended on the crRNA design, the secondary structure of the target templates, and the nature of the mismatches between the guide and the templates. To improve the specificity, we used an allele-specific PCR preamplification method called CASPER (Cas13a Allele-Specific PCR Enzyme Recognition). CASPER enabled specific and sensitive detection of KRASG12D with low DNA input. CASPER detected KRAS mutations in DNA extracted from patients' pancreatic ultrasound-guided fine-needle aspiration fluid. CONCLUSION: CASPER is easy to implement and is a versatile and reliable method that is virtually adaptable to any point mutation.
RESUMO
Advances in molecular medicine have placed nucleic acid detection methods at the center of an increasing number of clinical applications. Polymerase chain reaction (PCR)-based diagnostics have been widely adopted for their versatility, specificity, and sensitivity. However, recently reported clustered regularly interspaced short palindromic repeats-based methods have demonstrated equivalent to superior performance, with increased portability and reduced processing time and cost. In this study, we applied Specific High-Sensitivity Enzymatic Reporter UnLOCKing (SHERLOCK) technology to the detection of oncogenic rearrangements. We implemented SHERLOCK for the detection of BCR::ABL1 mRNA, a hallmark of chronic myeloid leukemia (CML), and EGFR DNA oncogenic alleles, frequently detected in glioblastoma and non-small cell lung cancer (NSCLC). SHERLOCK enabled rapid, sensitive, and variant-specific detection of BCR::ABL1 and EGFR alterations. Compared with the gold-standard PCR-based methods currently used in clinic, SHERLOCK achieved equivalent to greater sensitivity, suggesting it could be a new tool in CML and NSCLC, to detect low level of molecular residual disease.