Gonzalez-Cadavid N F, Zhou D, Battifora H, Bar-Eli M, Cline M J
Division of Hematology/Oncology, University of California, Los Angeles 90024-1678.
Oncogene. 1989 Sep;4(9):1137-40.
We have applied direct dideoxy sequencing of DNA fragments amplified in vitro by the polymerase chain reaction to the detection of mutations in exon 1 of the c-K-ras gene in human pancreatic adenocarcinomas. Four fresh frozen primary tumors, one metastatic tumor, and twelve formalin-fixed paraffin embedded tumors were analysed. Only three cases showed a possible mutation in codon 12 in a small population of cells, in contrast to the high frequency reported for this alteration with the RNAase A protection assay and allele-specific oligoxynucleotide hybridization. No major difference in sensitivity was found between DNA sequence analysis, and the latter method. Our results suggest that if c-K-ras mutations are indeed present in pancreatic adenocarcinomas at the high frequency reported by others, they must be confined to a small fraction of the cell population to escape detection by direct sequencing. Such a phenomenon would have implications for c-K-ras mutations in the pathogenesis of pancreatic adenocarcinomas.
我们已将通过聚合酶链反应体外扩增的DNA片段的直接双脱氧测序应用于检测人类胰腺腺癌中c-K-ras基因外显子1的突变。分析了4个新鲜冷冻的原发性肿瘤、1个转移性肿瘤和12个福尔马林固定石蜡包埋的肿瘤。与核糖核酸酶A保护试验和等位基因特异性寡核苷酸杂交报道的这种改变的高频率相反，只有3例在一小部分细胞中显示密码子12可能发生突变。DNA序列分析与后一种方法在敏感性上未发现重大差异。我们的结果表明，如果胰腺腺癌中确实存在其他人报道的高频率c-K-ras突变，那么它们必定局限于一小部分细胞群体中，从而通过直接测序无法检测到。这种现象将对胰腺腺癌发病机制中的c-K-ras突变产生影响。
