We evaluated the best tagging SNPs from our previous PTC study and additionally included SNPs in or near FOXE1 and NKX2-1 genes, known susceptibility loci for thyroid cancer.
Thyroid cancer (TC) is frequently associated with BRAF or RAS oncogenic mutations and RET/PTC rearrangements, with aberrant RAF-MEK-ERK and/or PI3K pathway activation.
BRAF(V600E) mutation analysis is superior to RAS point mutations and evaluation of RET/PTC rearrangements in the diagnosis of thyroid cancer, even in indeterminate lesions.
Twenty-four (27%) of 89 patients were diagnosed with thyroid cancer (50% papillary thyroid carcinoma [PTC], 50% follicular variant of papillary thyroid carcinoma [FVPTC]).
This study confirms the occurrence of synchronous MTC and PTC and is the first evidence of the co-existence of melanoma and distinct thyroid cancers of different origin.
The posttest probability of thyroid cancer was 100% for nodules positive for BRAF or RET-PTC, 70% for RAS or PAX8-PPARG, and 88% for molecular cytology overall.
In addition, expression of Sin1 and activation of AKT kinase were analyzed in fresh-frozen tissue samples (normal/tumor), primary cell cultures (papillary thyroid carcinoma [PTC]), and an established thyroid cancer cell line (medullary thyroid carcinoma) by Western blotting.
The molecular pathology of thyroid cancer is now better understood because of our ability to identify RET/PTC rearrangements and BRAF mutations in the aetiopathogenesis of the large majority of PTCs and the high prevalence of RAS mutations and PAX8/PPARgamma rearrangements in follicular patterned carcinomas (FTCs and follicular variant of PTCs).
Even though RET/PTC is a specific genetic event in the carcinomas, our results suggested the possibility of RET/PTC as "passenger" abnormalities rather than "driver" oncogenic mutation during thyroid cancer progression, warranting further studies on mechanisms and implication of RET gene instability.
In this study, we use an 18 Mb region on 10q11.2-21 containing the RET gene and its recombination partners, the H4 and NCOA4 (ELE1) genes, as a model chromosomal region frequently involved in RET/PTC rearrangements in thyroid cancer.
We analyzed the methylation pattern of 17 gene promoters in nine thyroid cancer cell lines and in 38 primary thyroid carcinomas (13 papillary thyroid carcinoma [PTC], 10 follicular thyroid carcinoma [FTC], 9 undifferentiated thyroid carcinoma [UTC], 6 medullary thyroid carcinoma [MTC]), 12 goiters, and 10 follicular adenomas (FA) by methylation- specific polymerase chain reaction (PCR).
Furthermore, activation of specific subtypes of the ret/PTC tyrosine kinase oncogene appears to be more common in radiation-associated thyroid cancers than in spontaneous thyroid cancers.
Present data suggest that: (1) the incidence of FAP-associated thyroid cancer probably has been underestimated in the past; (2) intensive screening could detect a larger than expected number of thyroid carcinomas; (3) systematic screening is recommended in patients with ocular patches and genetic mutation in exon 15; (4) Hashimoto-like findings do not exclude carcinoma but are a frequent accompanying finding; (5) despite frequent multicentricity and early lymph node involvement, FAP-associated thyroid tumors seem to have an excellent prognosis, in particular those showing ret-PTC activation.