Sensitive and specific KRAS somatic mutation analysis on whole-genome amplified DNA from archival tissues

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Kirsten RAS (KRAS) is a key signaling protein frequently mutated in various cancers.
• KRAS mutations often lead to a constitutively active protein, driving cancer progression.
• Accurate KRAS mutation detection is vital for cancer diagnosis and targeted therapy selection.

Purpose of the Study:

• To develop and validate a sensitive and specific two-step protocol for screening KRAS mutations.
• To enable mutation detection from limited DNA quantities available in formalin-fixed, paraffin-embedded (FFPE) tissues.
• To assess the feasibility of the protocol for clinical specimens, such as pancreatic cancers.

Main Methods:

• The protocol combines whole-genome amplification (WGA) with high-resolution melting analysis (HRM) as a prescreening step.
• Direct Sanger sequencing is used for confirmation of mutations identified by HRM.
• Target-specific primers and herring sperm DNA were employed to optimize WGA from low-cell-number FFPE samples.

Main Results:

• The WGA-HRM-Sanger sequencing protocol demonstrated high sensitivity and specificity for KRAS mutation detection.
• Successful WGA was achieved even with DNA from as few as 100 cells.
• The PCR amplification of whole-genome amplified DNA (wgaDNA) did not introduce genotypic changes, unlike unamplified DNA.

Conclusions:

• This two-step method is a feasible and effective approach for KRAS mutation screening in FFPE clinical specimens.
• The protocol's ability to work with limited DNA makes it valuable for molecular diagnostics.
• The methodology can potentially be adapted for screening mutations in other genomic regions.