Abstract
Despite the low mortality rates, well-differentiated thyroid carcinomas (WDTC) frequently relapse. BRAF and TERT mutations have been extensively related to prognosis in thyroid cancer. In this study, the methylation levels of selected CpGs (5-cytosine-phosphate-guanine-3) comprising a classifier, previously reported by our group, were assessed in combination with BRAF and TERT mutations. We evaluated 121 WDTC, three poorly-differentiated/anaplastic thyroid carcinomas (PDTC/ATC), 22 benign thyroid lesions (BTL), and 13 non-neoplastic thyroid (NT) tissues. BRAF (V600E) and TERT promoter (C228T and C250T) mutations were tested by pyrosequencing and Sanger sequencing, respectively. Three CpGs mapped in PFKFB2, ATP6V0C, and CXXC5 were evaluated by bisulfite pyrosequencing. ATP6V0C hypermethylation and PFKFB2 hypomethylation were detected in poor-prognosis (PDTC/ATC and relapsed WDTC) compared with good-prognosis (no relapsed WDTC) and non-malignant cases (NT/BTL). CXXC5 was hypomethylated in both poor and good-prognosis cases. Shorter disease-free survival was observed in WDTC patients presenting lower PFKFB2 methylation levels (p = 0.004). No association was observed on comparing BRAF (60.7%) and TERT (3.4%) mutations and prognosis. Lower PFKFB2 methylation levels was an independent factor of high relapse risk (Hazard Ratio = 3.2; CI95% = 1.1–9.5). PFKFB2 promoter methylation analysis has potential applicability to better stratify WDTC patients according to the recurrence risk, independently of BRAF and TERT mutations.
Highlights
Papillary (PTC) and follicular (FTC) thyroid carcinomas are the most prevalent thyroid tumors, designated as well-differentiated thyroid carcinomas (WDTC) [1]
telomerase reverse transcriptase encoding gene (TERT) promoter mutation has been reported in approximately 9% of PTC and in higher frequency in poorly-differentiated thyroid carcinomas (PDTC) (40%) and anaplastic thyroid carcinomas (ATC) (>70%) [1]
We previously reported a DNA methylation signature composed of 21 CpGs which was capable of discriminating WDTC samples according to the clinical outcome (86% of accuracy)
Summary
Papillary (PTC) and follicular (FTC) thyroid carcinomas are the most prevalent thyroid tumors, designated as well-differentiated thyroid carcinomas (WDTC) [1]. Papillary thyroid cancer harboring BRAF mutation is frequently described in patients with worse prognosis [5,6,7], mainly in older individuals [8]. TERT promoter mutation is highly prevalent in advanced PTC (61% of the cases) and FTC (71%) [14]. This gene encodes the catalytic subunit of telomerase, a ribonucleoprotein complex that maintains the telomere length, playing an important role in the tumorigenesis and cellular immortality [15]. TERT promoter and BRAF mutations were genotyped, and three differentially methylated CpGs, included in the previous reported prognostic signature, were assessed by bisulfite pyrosequencing. The molecular data were compared with the WDTC patient’s outcome, which was followed-up during 10.6 years in the median
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
