A novel platform for mutation detection in colorectal cancer using a PNA-LNA molecular switch

Detection of KRAS mutation in colorectal cancer (CRC) is important in the prediction of response to target therapy. The study aims to develop a novel mutation detection platform called the "PNA-LNA molecular switch" for the detection of KRAS mutation in CRC. We employed the enhanced binding specificity of peptide nucleic acid (PNA) and locked nucleic acid (LNA) in conjunction with a loop-mediated isothermal amplification (LAMP) approach to identify the mutation status of KRAS oncogene codon 12 (c.35G>T/G12V and c.35G>A/G12D) using synthetic oligonucleotides and colon cancer cell lines (Caco-2 and SW480). This method specifically blocked the amplification of the wild-type sequences while substantially amplifying the mutated ones, which was visualized by both colorimetric and fluorescence assays. We then checked the mutation profile of KRAS codon 12 in the DNA derived from tumor tissue samples (number of samples, n = 30) and circulating tumor cells (n = 24) from CRC patients. Finally, we validated the results by comparing them with the data obtained from DNA sequencing of colon tumors (n = 21) of the same CRC patients. This method showed excellent sensitivity (1 DNA copy/μl), reproducibility [relative standard deviation (%RSD) < 5%, for n = 3], and linear dynamic range (1 ag/μl-10 pg/μl, R² = 0.94). This platform is significantly faster, relatively cheaper, has superior sensitivity and specificity, and does not require any high-end equipment. To conclude, this method has the potential to be translated into clinical settings for the detection of mutations in diverse diseases and conditions.