Activation of c-K-ras mutations in human gastrointestinal tumors

Area of Science:

• Oncology
• Gastroenterology
• Molecular Biology

Background:

• Ras genes, particularly c-K-ras, are frequently activated oncogenes in human cancers.
• Limited and conflicting data exist on the prevalence of c-K-ras mutations in esophageal, gastric, and small bowel neoplasms.

Purpose of the Study:

• To investigate the frequency of c-K-ras codon 12 mutations in various gastrointestinal tumors.
• To compare mutation rates across different segments of the gastrointestinal tract.

Main Methods:

• DNA analysis of 262 formalin-fixed, paraffin-embedded gastrointestinal samples and tumors.
• Utilized a polymerase chain reaction-based restriction fragment length polymorphism assay to detect c-K-ras codon 12 mutations.

Main Results:

• c-K-ras mutations were detected in 2% of Barrett's esophagus, 5% of esophageal adenocarcinomas, 3% of gastric adenocarcinomas, and 0% of esophageal squamous cell carcinomas.
• Mutation rates were significantly higher in the lower GI tract: 40% in small bowel adenomas, 36% in small bowel adenocarcinomas, 40% in large bowel adenomas, and 37% in large bowel adenocarcinomas.
• No association was found between c-K-ras mutations and clinicopathological factors like age, gender, histology, grade, stage, location, or mortality.

Conclusions:

• The incidence of c-K-ras codon 12 mutations in small and large bowel tumors is approximately tenfold greater than in upper gastrointestinal tumors.
• These findings highlight a significant difference in c-K-ras oncogene activation between the upper and lower gastrointestinal tracts, with implications for cancer development and potential targeted therapies.