A single missense mutation in codon 918 of the RET proto-oncogene in sporadic medullary thyroid carcinomas

Area of Science:

• Oncology
• Genetics
• Molecular Biology

Background:

• The RET proto-oncogene plays a role in various human cancers, including medullary thyroid carcinoma (MTC).
• Germline and somatic mutations in the RET proto-oncogene have been associated with MTC syndromes and sporadic MTC.
• Understanding the incidence of RET mutations in Japanese MTC patients is crucial for diagnosis and treatment.

Purpose of the Study:

• To investigate the frequency of RET proto-oncogene mutations in Japanese patients with medullary thyroid carcinoma.
• To identify specific mutation types and their correlation with sporadic and hereditary forms of MTC.

Main Methods:

• Screening of exons 10 and 11 of the RET proto-oncogene using PCR-SSCP in 14 MTC cases.
• DNA sequencing of exons 10 and 11 for hereditary MTC cases.
• Analysis of exon 16 using Fok1 restriction enzyme digestion and DNA sequencing for all tumor samples.

Main Results:

• No structural abnormalities were found in exons 10 or 11 of the RET proto-oncogene in any of the examined cases.
• A common point mutation (ATG to ACG) at codon 918 in exon 16 was detected in four out of ten sporadic MTC cases.
• This mutation results in the replacement of methionine with threonine.

Conclusions:

• The findings suggest a potential association between a specific point mutation in exon 16 of the RET proto-oncogene and the oncogenesis of sporadic medullary thyroid carcinomas in Japan.
• Further research encompassing the entire RET proto-oncogene is warranted to fully elucidate its role in thyroid tumorigenesis.