Frequent mutations of NF2 and allelic loss from chromosome band 22q12 in malignant mesothelioma: Evidence for a two-hit mechanism of NF2 inactivation

We previously reported NF2 mutations in malignant mesothelioma (MM) cell li nes and corresponding primary tumors. We have now generated polyclonal anti bodies that specifically recognize the C-terminus of the NF2 protein. Weste rn blot analysis was performed on 25 MM cell lines, 14 of which showed no N F2 expression. Single-strand conformation polymorphism and DNA sequence ana lyses revealed NF2 mutations in each of these 14 cell lines. To explore the mechanism of inactivation of NF2, loss of heterozygosity analysis was perf ormed with two microsatellite markers located in the vicinity of the NF2 lo cus in chromosome band 22q12. Eighteen of the 25 cell lines (72%) showed lo sses at one or both loci tested. All cases exhibiting mutation and/or aberr ant expression of NF2 showed allelic losses, suggesting that inactivation o f NF2 in MM occurs via a two-hit mechanism. Genes Chromosomes Cancer 24:238 -242, 1999. (C) 1999 Wiley-Liss, Inc.