K-RAS ONCOGENE ACTIVATION IN ADENOCARCINOMA OF THE HUMAN PANCREAS - ASTUDY OF 82 CARCINOMAS USING A COMBINATION OF MUTANT-ENRICHED POLYMERASE CHAIN-REACTION ANALYSIS AND ALLELE-SPECIFIC OLIGONUCLEOTIDE HYBRIDIZATION

We examined 82 surgically resected or biopsied, formalin-fixed, paraff in-embedded primary adenocarcinomas of the pancreas for the presence o f activating point mutations in codon 12 of the K-ras oncogene. Mutati ons were detected using primer-mediated, mutant-enriched, polymerase c hain reaction-restriction fragment length polymorphism analysis and ch aracterized further by allele-specific oligonucleotide hybridization. This combination of mutant-enriched polymerase chain reaction-restrict ion fragment length polymorphism analysis and allele-specific oligonuc leotide hybridization results in a rapid and sensitive characterizatio n of the mutations in codon 12 of K-ras. Sixty-eight (83%) of the 82 c arcinomas examined harbored a point mutation. Of the 68 mutations, 33 (49%) were guanine to adenine transitions, 27 (39%) were guanine to th ymine transversions, and eight (12%) were guanine to cytosine transver sions. Mutations were found in carcinomas of the bead (61 of 75, 81%) as well as in carcinomas of the body or tail (seven of seven, 100%) of the pancreas. The overall prevalence of K-ras point mutations in aden ocarcinomas of the pancreas obtained from patients who smoked cigarett es at some point during their lives (88%; 86% in current smokers and 8 9% in ex-smokers) was greater than that seen in pancreatic adenocarcin omas from patients who never smoked cigarettes (68%, P = 0.046). The p resence of K-ras point mutations did not correlate with tumor ploidy, tumor proliferating index, or patient survival. These results demonstr ate that primer-mediated, mutant-enriched polymerase chain reaction-re striction fragment length polymorphism analysis combined with allele-s pecific oligonucleotide hybridization can be used to detect and charac terize mutations in codon 12 of the K-ras oncogene in formalin-fixed, paraffin-embedded tissues, and the results confirm that activating poi nt mutations in codon 12 of the K-ras oncogene occur frequently in ade nocarcinomas of the pancreas.