Gene rearrangements in radiation-induced thyroid carcinogenesis

Area of Science:

• Oncology
• Molecular Genetics
• Radiation Biology

Background:

• Radiation exposure is a known risk factor for pediatric thyroid cancer.
• Chernobyl accident provided insights into genetic alterations in radiation-induced papillary thyroid carcinomas (PTC).
• Understanding genetic determinants is crucial for mechanisms of radiation carcinogenesis.

Purpose of the Study:

• To investigate the molecular genetic landscape of post-Chernobyl papillary thyroid carcinomas (PTC) in children.
• To identify specific genetic aberrations associated with radiation-induced thyroid carcinogenesis.
• To correlate genetic alterations with tumor phenotype, biology, and clinical outcomes.

Main Methods:

• Molecular genetic analysis of 191 post-Chernobyl PTC samples.
• Techniques included RT-PCR, multiplex PCR, DNA sequencing, and 5'RACE.
• Point mutation determination utilized PCR with allele-specific oligonucleotide hybridization or SSCP and sequencing.

Main Results:

• RET rearrangements were the predominant genetic aberrations in radiation-induced pediatric PTC, unlike sporadic adult tumors.
• Frequent RET fusions involved ELE1 (PTC3) and H4 (PTC1), leading to constitutive activation of the RET tyrosine kinase.
• Specific RET fusions (e.g., ELE1/RET, H4/RET) correlated with tumor progression rates and histological variants.

Conclusions:

• Radioiodine uptake in the juvenile thyroid gland induces specific genetic aberrations.
• These genetic alterations, particularly RET rearrangements, are key determinants of the phenotype, biology, and clinical course of radiation-induced PTC.
• Findings highlight the role of aberrant RET activation in radiation-induced thyroid tumorigenesis.