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Heterogeneity of mesothelioma cell lines as defined by altered genomic structure and expression of the NF2 gene
B Deguen1, L Goutebroze, M Giovannini
1Laboratoire de Génétique des Tumeurs, INSERM U434, Fondation Jean Dausset-CEPH, Paris, France.
Abstract:
Germ-line mutations in the neurofibromatosis 2 (NF2) gene cause a susceptibility to the development of schwannoma and meningioma, 2 mostly benign tumors of neural crest origin. Bi-allelic inactivation of this gene has been observed in sporadic schwannomas and meningiomas. The NF2 gene may also be somatically inactivated in human malignant mesotheliomas (HMMs). Surprisingly, patients with an NF2 germ-line mutation have not been reported to be at an increased risk for this highly invasive tumor of mesodermal origin. To investigate in HMMs the silencing mechanism of the NF2 gene, we have analyzed its structure and expression in a series of 18 cell lines derived from HMMs. NF2 gene alterations were identified at a genomic level in 7 cell lines and were associated with a marked decrease in the concentration of the NF2 transcript. This decrease was also observed in 4 additional cell lines with no identified NF2 mutation. The 11 cell lines presented evidence suggesting deletion of one NF2 allele. None of these enabled the detection of normal or truncated forms of the NF2 protein by immunoprecipitational immunoblot analyses. In the 7 remaining cell lines, NF2 mRNA and NF2 protein were easily detectable. Among the latter, 4 lines were heterozygous for several chromosome 22 microsatellite loci, suggesting the presence of 2 NF2 alleles. Taken together, our data indicate that silencing of the NF2 gene is restricted to a subset of mesothelioma cell lines. The availability of established cell lines with different characterized NF2 status provides a powerful tool to explore the mechanism by which the NF2 protein exerts its tumor suppressive activity.
Insights
Neurofibromatosis 2 (NF2) gene silencing occurs in a subset of human malignant mesothelioma cell lines, impacting tumor development. This study provides tools to explore NF2
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Germ-line mutations in the neurofibromatosis 2 (NF2) gene are linked to schwannoma and meningioma development.
- Bi-allelic inactivation of the NF2 gene is observed in sporadic schwannomas and meningiomas.
- The NF2 gene's role in human malignant mesotheliomas (HMMs) and its inactivation mechanisms are not fully understood, especially given the lack of increased risk in NF2 germ-line mutation patients.
Purpose of the Study:
- To investigate the NF2 gene silencing mechanism in human malignant mesotheliomas (HMMs).
- To analyze the structure and expression of the NF2 gene in HMM cell lines.
- To provide a tool for exploring the tumor suppressive activity of the NF2 protein.
Main Methods:
- Analysis of NF2 gene structure and expression in 18 HMM cell lines.
- Identification of genomic alterations and transcript levels.
- Detection of NF2 protein using immunoprecipitational immunoblot analyses.
- Microsatellite analysis to assess allele status.
Main Results:
- NF2 gene alterations were found in 7 cell lines, associated with decreased NF2 transcript levels.
- NF2 transcript decrease was observed in 4 additional cell lines without identified mutations.
- 11 cell lines showed evidence of NF2 allele deletion, with no detectable NF2 protein.
- NF2 mRNA and protein were detectable in the remaining 7 cell lines, with 4 showing evidence of two NF2 alleles.
Conclusions:
- NF2 gene silencing is specific to a subset of mesothelioma cell lines.
- Established HMM cell lines with varying NF2 status offer a resource for studying NF2 protein's tumor suppressive functions.
- Further research is needed to elucidate the precise mechanisms of NF2 gene silencing and its role in mesothelioma pathogenesis.