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Anaplastic thyroid cancer: cytogenetic patterns by comparative genomic hybridization
Daishu Miura1, Nobuyuki Wada, Koei Chin
1Department of Surgery, University of California, San Francisco/Mount Zion Medical Center, San Francisco, California 94143-1674, USA.
Summary
Anaplastic thyroid cancer (ATC) frequently shows chromosomal abnormalities, especially when linked with follicular thyroid cancer (FTC). Papillary thyroid cancer (PTC) associations show fewer abnormalities, suggesting distinct genetic paths.
Area of Science:
- Genetics
- Oncology
- Cytogenetics
Background:
- Anaplastic thyroid cancer (ATC) is an aggressive form of thyroid malignancy.
- Differentiated thyroid cancer (DTC), including papillary thyroid cancer (PTC) and follicular thyroid cancer (FTC), can precede or coexist with ATC.
- Understanding the genetic underpinnings of ATC, particularly in relation to its differentiated precursors, is crucial for elucidating its pathogenesis.
Purpose of the Study:
- To investigate chromosomal abnormalities in anaplastic thyroid cancer (ATC) using comparative genomic hybridization (CGH) and flow cytometry.
- To compare the frequency and nature of chromosomal abnormalities in ATC associated with different types of differentiated thyroid cancer (DTC), namely PTC and FTC.
- To explore the potential correlation between DNA aneuploidy and chromosomal aberrations in ATC.
Main Methods:
- Analysis of 10 frozen ATC tissues and 5 thyroid cancer cell lines (1 ATC, 4 DTCs).
- Comparative genomic hybridization (CGH) was employed to detect chromosomal gains and losses.
- Flow cytometry was used to assess DNA content and determine ploidy status (aneuploidy vs. diploidy).
Main Results:
- Chromosomal abnormalities were detected in 50% of ATC tissues (24 abnormalities: 22 gains, 2 losses).
- ATCs associated with follicular thyroid cancer (FTC) exhibited significantly more chromosomal abnormalities compared to those associated with papillary thyroid cancer (PTC) (median 9.5 vs. 0.5, p=0.046).
- Aneuploidy was observed in 60% of ATC tissues, with good concordance between CGH and flow cytometry findings (p=0.048).
Conclusions:
- Chromosomal abnormalities are frequent in ATCs, particularly those arising in the context of FTC.
- The distinct patterns of chromosomal aberrations suggest that PTC and FTC possess different genetic backgrounds.
- These cytogenetic differences may be retained even after transformation to ATC, supporting distinct etiological pathways for ATC subtypes.