Zou Minjing, Baitei Essa Y, Alzahrani Ali S, BinHumaid Faisal S, Alkhafaji Dania, Al-Rijjal Roua A, Meyer Brian F, Shi Yufei
1 Department of Genetics, King Faisal Specialist Hospital and Research Centre , Riyadh, Saudi Arabia .
Thyroid. 2014 Aug;24(8):1256-66. doi: 10.1089/thy.2013.0610. Epub 2014 Jun 10.
RET/PTC rearrangement, RAS, and BRAF mutations are considered to be mutually exclusive in papillary thyroid carcinoma (PTC). However, although concomitant mutations of RET/PTC, RAS, or BRAF have been reported recently, their significance for tumor progression and survival remains unclear. We sought to examine the prognostic value of concomitant mutations in PTC.
We investigated 88 PTC for concomitant mutations. Mutation in BRAF exon 15, KRAS, NRAS, and HRAS were studied by polymerase chain reaction (PCR)-sequencing of tumor DNA; RET/PTC rearrangement was determined by reverse transcription (RT)-PCR-sequencing of tumor cDNA.
BRAF(V600E) was detected in 39 of 82 classic PTC (CPTC) and in all three tall-cell variants (49%, 42/85). KRAS mutation (p.Q61R and p.S65N) was detected in two CPTC (2%, 2/88) and NRAS(Q61R) in one CPTC and two follicular variant PTC (FVPTC; 3%, 3/88). KRAS(S65N) was identified for the first time in thyroid cancer and could activate mitogen-associated protein kinase (MAPK). RET/PTC-1 was detected in nine CPTC, one tall-cell variant, and two FVPTC. Concomitant BRAF(V600E) and KRAS, or BRAF(V600E) and RET/PTC-1 mutations were found in two CPTC, and six CPTC and one tall-cell variant, respectively. In total, 11 concomitant mutations were found in 88 PTC samples (13%), and most of them were in the advanced stage of disease (8/11, 73%; p<0.01).
Our data show that concomitant mutations are a frequent event in advanced PTC and are associated with poor prognosis. The concomitant mutations may represent intratumor heterogeneity and could exert a gene dosage effect to promote disease progression. KRAS(S65N) can constitutively activate the MAPK pathway.
RET/PTC重排、RAS和BRAF突变在甲状腺乳头状癌（PTC）中被认为是相互排斥的。然而，尽管最近有报道称存在RET/PTC、RAS或BRAF的伴随突变，但其对肿瘤进展和生存的意义仍不清楚。我们试图研究PTC中伴随突变的预后价值。
我们调查了88例PTC的伴随突变情况。通过肿瘤DNA的聚合酶链反应（PCR）测序研究BRAF外显子15、KRAS、NRAS和HRAS的突变；通过肿瘤cDNA的逆转录（RT）-PCR测序确定RET/PTC重排。
在82例经典型PTC（CPTC）中的39例以及所有3例高细胞变异型中检测到BRAF（V600E）（49%，42/85）。在2例CPTC中检测到KRAS突变（p.Q61R和p.S65N）（2%，2/88），在1例CPTC和2例滤泡变异型PTC（FVPTC）中检测到NRAS（Q61R）（3%，3/88）。KRAS（S65N）首次在甲状腺癌中被鉴定出来，并且可以激活丝裂原相关蛋白激酶（MAPK）。在9例CPTC、1例高细胞变异型和2例FVPTC中检测到RET/PTC-1。在2例CPTC中分别发现了BRAF（V600E）与KRAS或BRAF（V600E）与RET/PTC-1的伴随突变，在6例CPTC和1例高细胞变异型中也分别发现了这种伴随突变。在88例PTC样本中总共发现了11例伴随突变（13%），其中大多数处于疾病晚期（8/11，73%；p<0.01）。
我们的数据表明，伴随突变在晚期PTC中是常见事件，并且与预后不良相关。伴随突变可能代表肿瘤内异质性，并可能发挥基因剂量效应以促进疾病进展。KRAS（S65N）可以组成性激活MAPK途径。
