Mutational status of codons 12 and 13 of the N- and K-ras genes in tissue and cell lines derived from primary and metastatic prostate carcinomas.

N- and K-ras mutations at codons 12 and 13 were investigated using oligonucleotide hybridization analysis after PCR amplification and subsequent sequence analysis of the amplified DNA from the region of interest in the following prostatic primary and metastatic (met) carcinoma-derived cell lines: 1013L (primary), PC3 (bone met), DU145 (brain met), and LNCaP (lymph node met). We also examined fresh and archival primary and metastatic prostate tumor tissue and benign prostatic hypertrophy specimens. All prostatic cells and tissues examined contain at least one wild-type N- and K-ras allele with respect to codons 12 and 13. No mutations were found at N-ras codon 13. The only mutation seen in the prostatic cell lines and tissues was a K-ras codon 12 position II G-to-T transversion. Since these are established nonclonal cell lines that have adapted to tissue culture, it is possible that this mutation does not represent the mutational state of prostatic carcinoma in vivo. However, the lack of consistent mutation in the ras genes amplified directly from tumors suggests that when ras mutations occur during the progression of prostatic carcinoma, they are late-stage events not directly involved in the initial development of disease. Immunoprecipitation studies using pan-ras antibodies revealed no evidence of altered expression of Ras proteins.