We previously created a knock-in mutant mouse harboring a dominantly negative mutant thyroid hormone receptor beta (TRbeta(PV/PV) mouse) that spontaneously develops a follicular thyroid carcinoma similar to human thyroid cancer.
We used the human follicular thyroid cancer cell lines (FTC-133 and FTC-236 cells) to elucidate how functional expression of the THRB gene could affect tumorigenesis.
A total of 37 thyroid aspirates, including benign hyperplastic nodules (HBN, N = 16) and follicular thyroid carcinomas (FTC, N = 21) were analyzed for the presence of NRAS(61) and KRAS(13) mutations.
Total mutations found in the FNA and in the corresponding histological specimen in both series were: one PAX8/PPARG rearrangement in a follicular carcinoma (FC), four NRAS mutations [in two FCs, one papillary carcinoma and one follicular adenoma (FA)] and one HRAS mutation in one FA.
A similar genetic abnormality of N-ras genes at codon 61 between follicular adenoma and follicular carcinoma suggests that the mutation of N-ras at codon 61 might play a part in oncogenesis in follicular tumors.
In the present study, we aimed to investigate the clinicopathological aspects of a large series of follicular thyroid carcinomas (FTCs) in paediatric patients and to analyse the point mutations in codons 12, 13 and 61 of NRAS, HRAS and KRAS genes and the rearrangements of PAX8-PPARG.
To our knowledge, this is the first reported case of synchronous and metastatic primary papillary and follicular carcinomas, and the first report of synchronous BRAF V600E mutated papillary and NRAS mutated follicular carcinoma.
Total mutations found in the FNA and in the corresponding histological specimen in both series were: one PAX8/PPARG rearrangement in a follicular carcinoma (FC), four NRAS mutations [in two FCs, one papillary carcinoma and one follicular adenoma (FA)] and one HRAS mutation in one FA.
Finally, KRAS2 was found to be differentially expressed (P<0.05) when comparing the papillary thyroid carcinoma and follicular thyroid carcinoma groups.
In the present study, we aimed to investigate the clinicopathological aspects of a large series of follicular thyroid carcinomas (FTCs) in paediatric patients and to analyse the point mutations in codons 12, 13 and 61 of NRAS, HRAS and KRAS genes and the rearrangements of PAX8-PPARG.
In accordance with our previous reports, we found that observation of concomitant CD26-positive and PTEN-negative status in cases of follicular adenoma suggests a state close to follicular carcinoma or progression to cancer, thus warranting careful follow-up.
We found PIK3CA copy gain (defined as four or more copies) in nine of 31 FTC (29%), 20 of 141 PTC (14%), and five of 62 FTA (8%); PIK3CA gene mutations in four of 31 FTC (13%), one of 141 PTC (1%), and none of 62 FTA (0%); Ras mutations in three of 31 FTC (10%) and none of the 141 PTC and 62 FTA; and PTEN mutations in two of 31 FTC (6%) and none of 62 FTA (0%).
Similarly, there is increasing evidence demonstrating that mutations leading to activation of the phosphatidylinositol 3- kinase (PI3K)/AKT effectors -PTEN and PI3KCa- are essential for the pathogenesis of follicular thyroid carcinoma (FTC).
Caveolin-1 is of particular functional interest because it has been shown to interact with PTEN, the tumor suppressor gene mutated in Cowden syndrome, an inherited multiple hamartoma syndrome that includes predisposition to FTC.
CS/CS-like patients have elevated risks of follicular thyroid cancer due to PTEN pathogenic mutations and of papillary thyroid cancer from SDHx and KLLN alterations.
Here, we show SDHD-G12S and SDHD-H50R lead to impaired PTEN function through alteration of its subcellular localization accompanied by resistance to apoptosis and induction of migration in both papillary and follicular thyroid carcinoma cell lines.
The authors found PTEN methylation to become progressively higher from benign thyroid adenoma to follicular thyroid cancer and to aggressive anaplastic thyroid cancer, which harbored activating genetic alterations in the PI3K/AKT pathway correspondingly with a progressively higher prevalence.