CHARACTERIZATION OF P53 GENE-MUTATIONS IN ESOPHAGEAL SQUAMOUS-CELL CARCINOMA CELL-LINES - INCREASED FREQUENCY AND DIFFERENT SPECTRUM OF MUTATIONS FROM PRIMARY TUMORS

We screened 29 human esophageal squamous cell carcinoma (ESC) cell lin es for mutations of the p53 gene through all coding exons and exon-int ron junctions. Mutations were found in 22 cell lines (76%), consisting of 20 single-base substitutions, 2 small deletions and 1 single-base insertion. Out of 20 single-base substitution, 5 were located at the e xon-intron junctions and mRNAs with abnormal splicing were detected by RT-PCR in 4 of them. A G:C to T:A transversion, which occurred rather frequently in resected tumors of ESC, was observed in only I cell lin e, and, instead, frequent transitions at CpG sites were detected. We a lso examined 65 fresh tumor materials, from all of which we tried to e stablish cell lines, and detected mutations in 26 samples (40%). Compa red with the results in these fresh tumor materials, the mutation inci dence In cell lines was significantly high and the mutation spectrum w as also different. From these 65 tumors, 10 cell lines were establishe d, including 3 cell lines from 26 tumors with p53 mutations and 7 cell lines from 39 without mutations, which indicates that there was no si gnificant correlation between the status of the p53 gene in each fresh tumor and its establishment as a cell line. In 7 cell lines establish ed from mutation-free tumors, newly acquired mutations were detected i n 5, which suggests that mutations might occur during the process of e stablishing cell lines. (C) 1996 Wiley-Liss, Inc.