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Genetic instability and mutation of the TGF-beta-receptor-II gene in ampullary carcinomas
1Department of Pathology, Faculty of Medicine, University of Tokyo, Japan.
Abstract:
Ampullary carcinomas are relatively rare cancers of which very little is known in terms of carcinogenetic mechanisms at the molecular level. Genetic instability caused by mutations of mismatch-repair genes has been demonstrated to be responsible for hereditary non-polyposis colorectal cancers and a sub-set of sporadic colorectal cancers. In some of those tumors showing genetic instability, the transforming-growth-factor-beta(TGF-beta)-receptor-II gene has been found to be mutated in repetitive sequences and considered to be a target of replication error. We studied the role of genetic instability and associated TGF-beta-receptor-II-gene mutations in a series of 18 sporadic cases by analyzing 5 microsatellite loci (D2S123, D3S1029, D5S409, TP53 and BAT26) and by sequencing a poly-A repeat (nucleotides 709-718) in the TGF-beta-receptor-II gene. Microsatellite instability was observed in 4 (22.2%) and gene mutations in 14 (77.8%) cases. These data indicate that the TGF-beta-receptor-II gene might be a preferential target of genetic instability whose alteration might be specifically advantageous and constitute a common step in the development of ampullary carcinomas.
Insights
Genetic instability and transforming growth factor beta receptor II (TGF-β-RII) gene mutations are implicated in ampullary carcinoma development. TGF-β-RII gene alterations may be a common, advantageous step in this rare cancer
Area of Science:
- Oncology
- Molecular Biology
- Cancer Genetics
Background:
- Ampullary carcinomas are rare, with poorly understood molecular carcinogenetic mechanisms.
- Genetic instability, driven by mismatch-repair gene mutations, is key in some colorectal cancers.
- Transforming growth factor beta receptor II (TGF-β-RII) gene mutations are observed in tumors with genetic instability.
Purpose of the Study:
- To investigate the role of genetic instability and TGF-β-RII gene mutations in sporadic ampullary carcinomas.
- To determine if TGF-β-RII gene alterations are a common event in ampullary cancer development.
Main Methods:
- Analyzed 18 sporadic ampullary carcinoma cases.
- Assessed microsatellite instability at 5 loci (D2S123, D3S1029, D5S409, TP53, BAT26).
- Sequenced the poly-A repeat in the TGF-β-RII gene.
Main Results:
- Microsatellite instability was detected in 22.2% of cases.
- TGF-β-RII gene mutations were found in 77.8% of cases.
- The TGF-β-RII gene appears to be a frequent target in ampullary carcinomas.
Conclusions:
- Genetic instability and TGF-β-RII gene mutations are significant in ampullary carcinoma.
- Alterations in the TGF-β-RII gene may provide a selective advantage, contributing to cancer development.
- These findings highlight potential molecular pathways in rare ampullary cancers.