Rapid and sensitive detection of KRAS mutation after fast-COLD-PCR enrichment and high-resolution melting analysis.

KRAS mutations exhibit significant predictive and prognostic value in cancer. Efficient, sensitive, and accurate molecular approaches are required to evaluate KRAS mutation status, even when mutant alleles are restricted to a small portion of a clinical sample, which otherwise contains wild-type alleles. We describe a highly sensitive method to detect KRAS mutations by high-resolution melting (HRM) analysis after mutation enrichment by fast-COLDpolymerase chain reaction (PCR). Using 10 ng of starting DNA and after fast-COLD-PCR of a 76-bp region containing KRAS codons 12 and 13; the amplicons undergo a nested conventional PCR reaction followed by HRM analysis. Samples exhibiting aberrant melting profiles are sequenced to identify mutation type and position. Serial dilution experiments indicate a sensitivity of approximately 0.3% mutant-to-wild type for HRM-based mutation detection and the ability to directly sequence mutation-containing samples. A number of lung adenocarcinoma specimens earlier characterized were screened. Fast-COLD-PCR-HRM analysis correctly identified KRAS mutations and also showed a previously undetected, low-level missense GGT > TTT complex mutation. On account of the short target regions and low requirement of starting DNA, this rapid, cost-effective, and sensitive fast-COLD-PCR-HRM approach is expected to find broad application for detecting low-abundance KRAS mutations in a wide range of clinical specimens.