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Mxi1 mutations in human neurofibrosarcomas
Abstract:
Mxi1 is thought to negatively regulate Myc function and may therefore be a potential tumor suppressor gene. Little effort has yet been made to find alterations involving this gene in human solid tumors. We screened 31 human gastric cancers, 7 esophageal cancers, 85 bone and soft tissue tumors of various types, including 4 neurofibrosarcomas. We also examined 29 human tumor cell lines consisting of 12 esophageal cancers, 7 glioma/glioblastomas and 10 others for Mxi1 mutations in exons 1, 2, 4 (HLH domain), 5 and 6. Polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and subsequent sequencing revealed three distinct polymorphisms in the intron-exon boundary upstream from exon 6. We discovered a missense mutation, GCA to GTA (Ala 54 Val), in exon 2 in a neurofibrosarcoma patient (case 1), two missense mutations, AAA to CAA (Lys 118 Gln) and GAA to GGA (Glu 154 Gly) in exon 5 of another neurofibrosarcoma patient (case 2), and 3 amino acid substitutions, GTG to GCG (Val 179 Ala), GTT to GCT (Val 181 Ala) and TTC to CTC (Phe 186 Leu), in a third neurofibrosarcoma patient (case 3). In case 3, loss of heterozygosity was also demonstrated by informative (TTC)3/(TTC)2 polymorphism. Our data demonstrate that mutations occur in the Mxi1 gene in neurofibrosarcoma. Missense mutations in the functional domain of Mxi1 in these cases may be involved in the pathogenesis of neurofibrosarcoma.
Insights
Mutations in the Mxi1 gene, a potential tumor suppressor, were identified in neurofibrosarcoma patients. These Mxi1 gene alterations may contribute to the development of neurofibrosarcoma.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- The Mxi1 gene is implicated in negatively regulating Myc, suggesting a role as a tumor suppressor.
- Limited research has explored Mxi1 gene alterations in human solid tumors.
Purpose of the Study:
- To investigate mutations in the Mxi1 gene across various human solid tumors and cell lines.
- To identify specific Mxi1 gene alterations and their potential role in neurofibrosarcoma pathogenesis.
Main Methods:
- Screening of 31 gastric cancers, 7 esophageal cancers, and 85 bone and soft tissue tumors, including 4 neurofibrosarcomas.
- Analysis of 29 human tumor cell lines (12 esophageal cancers, 7 glioma/glioblastomas, 10 others) for Mxi1 mutations.
- Utilized Polymerase Chain Reaction-Single-Strand Conformation Polymorphism (PCR-SSCP) and sequencing to detect mutations in Mxi1 exons.
Main Results:
- Identified three polymorphisms in the intron-exon boundary upstream from exon 6.
- Discovered missense mutations in Mxi1 exon 2 (Ala54Val) in one neurofibrosarcoma patient.
- Found multiple missense mutations in Mxi1 exon 5 (Lys118Gln, Glu154Gly, Val179Ala, Val181Ala, Phe186Leu) in two other neurofibrosarcoma patients, with loss of heterozygosity in one case.
Conclusions:
- Demonstrated the occurrence of Mxi1 gene mutations in neurofibrosarcoma.
- Suggests that missense mutations within the functional domain of Mxi1 may play a role in the pathogenesis of neurofibrosarcoma.