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Somatic mitochondrial DNA (mtDNA) mutations in papillary thyroid carcinomas and differential mtDNA sequence variants
J J Yeh1, K L Lunetta, N J van Orsouw
1Clinical Cancer Genetics Program, Ohio State University Comprehensive Cancer Center, Columbus 43210, USA.
Abstract:
Somatic mutations in mtDNA have recently been identified in colorectal tumours. Studies of oncocytic tumours have led to hypotheses which propose that defects in oxidative phosphorylation may result in a compensatory increase in mitochondrial replication and/or gene expression. Mutational analysis of mtDNA in thyroid neoplasia, which is characterised by increased numbers of mitochondria and is also one of the most common sites of oncocytic tumours. has been limited to date. Using the recently developed technique of two-dimensional gene scanning, we have successfully examined 21 cases of thyroid tumours, six cases of non-neoplastic thyroid pathology, 30 population controls, nine foetal thyroid tissues and nine foetal tissues of non-thyroid origin, either kidney or liver. We have identified three different somatic mutations (23%) in papillary thyroid carcinomas. In addition, we have found significant differential distributions of mtDNA sequence variants between thyroid carcinomas and controls. Interestingly, these variants appear to be more frequent in the genes which encode complex I of the mitochondrial electron transport chain compared to normal population controls. These findings suggest first, that somatic mtDNA mutations may be involved in thyroid tumorigenesis and second, that the accumulation of certain non-somatic variants may be related to tumour progression in the thyroid.
Insights
Somatic mitochondrial DNA (mtDNA) mutations were found in 23% of papillary thyroid carcinomas, suggesting a role in thyroid cancer development. Specific mtDNA variants were also more common in tumors, potentially influencing disease progression.
Area of Science:
- Mitochondrial genetics
- Cancer biology
- Thyroid pathology
Background:
- Somatic mutations in mitochondrial DNA (mtDNA) are implicated in colorectal tumors.
- Oncocytic tumors suggest that oxidative phosphorylation defects may increase mitochondrial replication or gene expression.
- Thyroid neoplasia, common in oncocytic tumors, has limited mtDNA mutational analysis.
Purpose of the Study:
- To investigate the presence and role of somatic mtDNA mutations in thyroid tumorigenesis.
- To analyze mtDNA sequence variants in thyroid carcinomas and compare them to controls.
- To explore the association between mtDNA alterations and thyroid tumor progression.
Main Methods:
- Utilized two-dimensional gene scanning for mtDNA analysis.
- Examined 21 thyroid tumors, 6 non-neoplastic thyroid tissues, 30 population controls, and 9 fetal tissues.
- Compared mtDNA sequence variants between thyroid carcinomas and control groups.
Main Results:
- Identified three distinct somatic mtDNA mutations in 23% of papillary thyroid carcinomas.
- Found significant differences in mtDNA sequence variant distribution between thyroid carcinomas and controls.
- Observed a higher frequency of certain variants in genes encoding Complex I of the mitochondrial electron transport chain in tumors.
Conclusions:
- Somatic mtDNA mutations may play a role in the development of thyroid tumors.
- The accumulation of specific non-somatic mtDNA variants might be linked to thyroid tumor progression.
- Further research into mtDNA's role in thyroid cancer is warranted.