[Detection of ras gene mutations of pancreatic tumors by polymerase chain reaction and direct sequencing method].

Ras genes (H-,K-,N-ras) are converted to active oncogenes by point mutations occurring in either codon 12, 13 or 61. We analyzed 19 pancreatic tumors (formalin fixed paraffin embedded tissue) of these codons by a method to directly sequence nucleotides around codons 12/13 and 61 of the three ras genes, using polymerase chain reaction and direct sequencing method. Of 19 pancreatic tumors, all 17 duct cell carcinomas involving 2 mucous producing pancreatic cancers had point mutations of the K-ras codon 12, but 2 islet cell tumors had ano point mutation around codons 12, 13, 61 of the three ras genes. Extremely high incidence of ras gene mutation may be relevant to certain pathogenesis of pancreatic cancers.