Alterations of the BRAF gene in thyroid tumors

BRAF belongs to the RAF family of protein kinases that are important components of the MAPK signaling pathway mediating cell growth, differentiation and survival. Activating point mutation of the BRAF gene resulting in V600E (previously designated as V599E) is a common event in thyroid papillary carcinoma, being found in approx 40% of this tumor. It has strong association with classical papillary carcinoma and tall cell and possibly Warthin-like variants. This mutation also occurs in thyroid poorly differentiated and anaplastic carcinomas, usually those containing areas of papillary carcinoma. Alterations in the BRAF gene do not overlap with RAS mutations and RET/PTC rearrangement, indicating that activation of one of the effectors of the MAPK pathway is sufficient for papillary thyroid carcinogenesis. Recently, another mechanism of BRAF activation has been identified, which involves chromosome 7q inversion that results in the AKAP9-BRAF fusion. It is rare in sporadic papillary carcinomas and is more common in tumors associated with radiation exposure. Yet another mechanism of BRAF activation may involve copy number gain, which is seen in a significant portion of thyroid follicular tumors of both conventional and oncocytic (Hürthle cell) types.     

甲状腺乳头状癌中BRAFV599E点突变与RET/PTC融合基因的检测

目的检测甲状腺乳头状癌(PTC)及其他类型甲状腺良恶性肿瘤中BRAFV599E的点突变及 RET/PTC1、3融合基因的表达状况,探讨二者与PTC临床病理学特征的关系.方法用聚合酶链反应(PCR)及逆转录(RT)-PCR分别检测95例石蜡与新鲜甲状腺病变组织中BRAFV599E点突变和RET/PTC1、3融合基因.结果 (1)仅在PTC中检测到BRAFV599E的突变,突变率56%(37/66),在经典型PTC和高细胞型PTC中突变率分别为70%(29/41)和2/3,在滤泡型PTC及其他类型甲状腺病变中未检测到BRAFV599E的突变.统计学分析BRAF突变与性别、年龄、伴慢性淋巴细胞浸润及淋巴结转移无明显关系(P>0.05).(2)PTC中RET/PTC检出率21.2%(14/66),其中5例RET/PTC1阳性(7.6%),9例RET/PTC3阳性(13.6%).RET/PTC融合基因阳性的14例PTC中未检测到BRAFV599E突变.其余29例良恶性病例中未检测到RET/PTC融合基因.RET/PTC融合基因的表达与PTC的临床病理学特征无明显关系(P>0.05).结论 (1)BRAFV599E突变和RET/PTC融合基因是PTC较特征性的遗传学改变,可作为PTC诊断和鉴别诊断提供分子学的依据,BRAFV599E突变可能是甲状腺乳头状癌表型的重要决定因素之一;(2)BRAFV599E突变与PTC的经典型和高细胞型两种主要亚型密切相关;(3)BRAFV599E突变与RET/PTC融合基因可能在PTC中是独立事件.     

Immunohistochemistry is highly sensitive and specific for detecting the BRAF V600E mutation in papillary thyroid carcinoma

The V600E mutation in the B-type Raf kinase (BRAF) gene is a common genetic change in cases of papillary thyroid carcinoma (PTC) that appears to play a key role in the development and progression of this disease. We sought to assess the sensitivity and specificity of immunohistochemical detection of this mutation with a V600E mutated BRAF antibody in a Chinese PTC cohort. In this study, we used fully automated immunohistochemistry (IHC) assay with a BRAF V600E (VE1) mouse monoclonal primary antibody to screen for the BRAF V600E mutation in 556 cases of PTC. Moreover, to verify the IHC staining results, real-time PCR was applied to detect this mutation in the same patient cohort. Among the 556 cases in the examined primary PTC cohort, 414 (74.5%) cases and 419 (75.4%) cases were positive for the BRAF V600E mutation by IHC staining and by real-time PCR, respectively. The real-time PCR results indicated that the sensitivity and specificity of IHC staining for the BRAF V600E mutation were 98.8% and 100%, respectively. The BRAF V600E mutation was common among Chinese patients with primary PTC, and was strongly correlated with older patient age and the conventional subtype of PTC but was not associated with parameters of clinicopathological aggressiveness. The fully automated IHC is a reliable technique that can serve as an alternative to molecular biological approaches for the routine detection of the BRAF V600E mutation in PTC patients.     

LIMD2 Is Overexpressed in BRAF V600E-Positive Papillary Thyroid Carcinomas and Matched Lymph Node Metastases

We previously described that LIM domain containing 2 (LIMD2) overexpression was closely correlated with metastatic process in papillary thyroid carcinoma (PTC). We here evaluated the expression of LIMD2 in a series of non-metastatic and metastatic PTC and their matched lymph node metastases via immunohistochemistry. LIMD2 was expressed in 74 (81%) of primary PTC and 35 (95%) of lymph node metastases. Sub-analysis performed in 37 matched samples demonstrated that in four cases, LIMD2 is expressed in lymph node metastases, while it is not expressed in primary tumors. Moreover, in eight cases, the staining intensity of LIMD2 was stronger in the patient-matched lymph node metastases than in the primary tumors. Next, the expression of LIMD2 was correlated with clinical pathological parameters and BRAF V600E and RET/PTC mutational status. The expression of LIMD2 in primary tumors was correlated with the presence of BRAF V600E mutation (P =?0.0338). Western blot analysis in thyroid cell lines demonstrated that LIMD2 is expressed in two PTC cell lines, while it is not expressed in normal thyroid and follicular thyroid carcinoma cell lines. Importantly, its expression was higher in a PTC cell line that harbors BRAF V600E mutation than in a PTC cell line that harbors RET/PTC1. The available genomic profiling data generated by The Cancer Genome Atlas Research Network confirmed that LIMD2 expression is higher in BRAF-like PTC samples. Our data suggest that LIMD2 may play an important role in the metastatic process of PTC, predominantly in BRAF V600E-positive tumors.     

Diffuse sclerosing variant of papillary thyroid carcinoma: lack of BRAF mutation but occurrence of RET/PTC rearrangements.

Diffuse sclerosing variant of papillary thyroid carcinoma (PTC) is a rare tumour with a characteristic morphology as well as a strong preponderance for younger female patients. The T1799A missense mutation in exon 15 of the BRAF gene and RET/PTC rearrangement have been identified as the dominant genetic tumour initiation events in the pathogenesis of PTC leading to a constitutive activation of the RAS-RAF-MAPK pathway. In order to elucidate the pathogenesis of diffuse sclerosing variant of PTC, the prevalence of BRAF mutation and RET/PTC were determined by RT-polymerase chain reaction and DNA-sequence analysis in tumour samples of seven patients with this variant (all female, age range 15-61 years, mean 33.3 years) without prior radiation exposure. None of these cases showed a BRAF mutation. RET/PTC1 (two out of seven) and RET/PTC3 (one out of seven), which have been shown in large PTC series to comprise together more than 90% of RET/PTC types, were found in <50% of the cases investigated. All seven samples expressed the RET tyrosine kinase domain but lacked its extracellular domain potentially suggesting the existence of rare types of RET/PTC rearrangement in the four remained cases of diffuse sclerosing variant of PTC. Regarding this subtype, our study confirmed the paradigm of a mutual exclusivity between RET/PTC and BRAF in PTC. Additionally, this rare variant of papillary thyroid carcinoma may represent a tumour type susceptible to RET-targeted therapies.     

A new BRAF gene mutation detected in a case of a solid variant of papillary thyroid carcinoma

BRAF gene mutations have been frequently detected in papillary thyroid carcinoma (PTC). Moreover, there is a close association between the type of mutation and the PTC histotype: BRAF(V600E) is associated with conventional PTC and with histological variants of PTC displaying a prominent papillary growth pattern, whereas BRAF(K601E) is associated with the follicular variant of PTC. We report the detection of a novel BRAF triplet deletion in a case of PTC displaying a predominantly solid growth pattern. The deletion leads to the replacement of a valine and a lysine by a glutamate in the BRAF activation segment (BRAF(VK600-1E)), thus mimicking partially the 2 BRAF mutations previously described. Our study reinforces the existence of a close relationship between the occurrence of some types of BRAF mutation and some PTC histotypes. The genetic study of more cases of the solid variant of PTC is necessary to find whether there exists a significant association between the occurrence of BRAF(VK600-1E) and such PTC histotype.     

In melanocytic lesions the fraction of BRAF V600E alleles is associated with sun exposure but unrelated to ERK phosphorylation.

BRAF(V600E) mutation has been frequently reported in different types of melanocytic lesions, but its role in melanomagenesis is poorly understood, having been associated with either the proliferative-induced MAPK pathway activation or the acquisition of oncogene-driven senescence. The presence of BRAF alterations has been related to sun exposure, although the molecular mechanisms underlying this event are only partly known. To elucidate the relationships among BRAF/NRAS alterations, MAPK pathway activation, and sun exposure, we examined 22 acquired nevi and 18 cutaneus melanomas from 38 patients. Microdissected tissues from each lesion were subjected to BRAF/NRAS mutation analysis by sequencing, allele-specific PCR and pyrosequencing assay. The same lesions were also examined for the expression of phosphorylated ERK1/2. Phototype and an accurate history of sun exposure were evaluated for each patient. BRAF(V600E) mutation was detected in 50% of the acquired nevi and in 70% of the cutaneus melanomas in the absence of NRAS alterations. The fraction of alleles carrying BRAF(V600E) substitution was variable but strongly associated with sun exposure. In contrast, no relationship was evidenced between the presence of this mutation and patients' phototype, phosphorylated ERK1/2 expression, or Clark's level. Our findings indicate that in melanocytic lesions, BRAF(V600E) mutation can affect a subset of the cells and is associated with the type and quantity of sun exposure. This mutation is independent of the nevo-melanoma progression and unrelated to ERK phosphorylation, suggesting that alternative mechanisms to the MAPK activation are also involved in this type of transformation.     

The intermediate-activity L597VBRAF mutant acts as an epistatic modifier of oncogenic RAS by enhancing signaling through the RAF/MEK/ERK pathway

(L597V)BRAF mutations are acquired somatically in human cancer samples and are frequently coincident with RAS mutations. Germline (L597V)BRAF mutations are also found in several autosomal dominant developmental conditions known as RASopathies, raising the important question of how the same mutation can contribute to both pathologies. Using a conditional knock-in mouse model, we show that endogenous expression of (L597V)Braf leads to approximately twofold elevated Braf kinase activity and weak activation of the Mek/Erk pathway. This is associated with induction of RASopathy hallmarks including cardiac abnormalities and facial dysmorphia but is not sufficient for tumor formation. We combined (L597V)Braf with (G12D)Kras and found that (L597V)Braf modified (G12D)Kras oncogenesis such that fibroblast transformation and lung tumor development were more reminiscent of that driven by the high-activity (V600E)Braf mutant. Mek/Erk activation levels were comparable with those driven by (V600E)Braf in the double-mutant cells, and the gene expression signature was more similar to that induced by (V600E)Braf than (G12D)Kras. However, unlike (V600E)Braf, Mek/Erk pathway activation was mediated by both Craf and Braf, and ATP-competitive RAF inhibitors induced paradoxical Mek/Erk pathway activation. Our data show that weak activation of the Mek/Erk pathway underpins RASopathies, but in cancer, (L597V)Braf epistatically modifies the transforming effects of driver oncogenes.     

BRAF mutations are associated with some histological types of papillary thyroid carcinoma

Mutations in the BRAF gene have recently been detected in a wide range of neoplastic lesions with a particularly high prevalence in melanoma and papillary thyroid carcinoma (PTC). The hot-spot mutation BRAF(V599E) is frequently detected in PTC (36-69%), in contrast to its absence in other benign or malignant thyroid lesions. In order to unravel whether there is any association between the occurrence of the BRAF mutation and the histological pattern of PTC, in this study a previous series of 50 PTCs was extended to 134 cases, including ten cases of PTC-related entities-hyalinizing trabecular tumour (HTT) and mucoepidermoid carcinoma (MEC). Using PCR/SSCP and sequencing, the BRAF(V599E) mutation was detected in 45 of the 124 PTCs (36%). No mutations were detected in any case of HTT and MEC. BRAF(V599E) was present in 75% of Warthin-like PTCs and 53% of conventional PTCs, whereas no BRAF(V599E) mutations were detected in any of the 32 cases of the follicular variant of PTC. BRAF(V599E) was also detected in 6 of 11 cases of the oncocytic variant of PTC that displayed a papillary or mixed follicular-papillary growth pattern and in none of the four oncocytic PTCs with a follicular growth pattern. A distinct mutation in BRAF (codon K600E) was detected in three cases of the follicular variant of PTC. This study has confirmed the high prevalence of BRAF(V599E) in PTC and has shown that the mutation is almost exclusively seen in PTC with a papillary or mixed follicular-papillary growth pattern, regardless of the cytological features of the neoplastic cells. The results support the existence of an oncocytic variant of PTC that should be separated from the oncocytic variant of follicular carcinoma and suggest that the follicular variant of PTC may be genetically different from conventional PTC.     

The Relationship of the BRAFV600E Mutation and the Established Prognostic Factors in Papillary Thyroid Carcinomas

It has been shown that BRAF(V600E) mutation in papillary thyroid carcinomas (PTC) is associated both with pathogenesis and poor prognosis. In this study, we aimed to investigate the relationship of the BRAF(V600E) mutation and the established prognostic factors in a cohort of Turkish patients with PTC. Forty-six cases of papillary thyroid carcinoma have been evaluated for the presence of BRAF(V600E) mutation. BRAF(V600E) has been examined by restriction fragment length polymorphism. BRAF(V600E) mutation status has been compared with well-known histopathological and clinical prognostic parameters such as invasion of thyroid capsule, extrathyroidal extension, and the presence of lymph node and/or distant metastasis. We have found that BRAF(V600E) mutation was present in the majority of our cases (40/46). Considering the stage of the disease, five of the negative cases were in stage 1 while the remaining one was in stage 2. Only one BRAF(V600E) negative case has shown extrathyroidal extension and lymph node metastasis. All four patients with distant metastasis had BRAF(V600E) mutation. Statistical analyses revealed that there are no significant relationship between the BRAF(V600E) mutation and the established prognostic factors. We found a relatively higher BRAF(V600E) mutation rate in classical type PTC than in other similar studies. We think that the limited number of our cases may either weaken or mask some potentially important relationship between BRAF(V600E) mutation and the established prognostic factors.     

Novel V600E BRAF mutations in imatinib-naive and imatinib-resistant gastrointestinal stromal tumors

BRAF and NRAS are commonly mutated in cancer and represent the most frequent genetic events in malignant melanoma. More recently, a subset of melanomas was shown to overexpress KIT and harbor KIT mutations. Although most gastrointestinal stromal tumors (GISTs) exhibit activating mutations in either KIT or PDGFRA, about 10% of the cases lack mutations in these genes. It is our hypothesis following the melanoma model that mutations in BRAF or NRAS may play a role in wild-type GIST pathogenesis. Alterations in RAS/MEK/ERK pathway may also be involved in development of imatinib resistance in GIST, particularly in tumors lacking secondary KIT or PDGFRA mutations. Imatinib-naive wild-type GISTs from 61 patients, including 15 children and 28 imatinib-resistant tumors without secondary KIT mutations were analyzed. Screening for hot spots mutations in BRAF (exons 11 and 15) and NRAS (exons 2 and 3) was performed. A BRAF exon 15 V600E was identified in 3 of 61 GIST patients, who shared similar clinical features, being 49- to 55-years-old females and having their tumors located in the small bowel. The tumors were strongly KIT immunoreactive and had a high risk of malignancy. An identical V600E BRAF mutation was also identified in one of 28 imatinib resistant GIST lacking a defined mechanism of drug resistance. In conclusion, we identified a primary BRAF V600E mutations in 7% of adult GIST patients, lacking KIT/PDGFRA mutations. The BRAF-mutated GISTs show predilection for small bowel location and high risk of malignancy. A secondary V600E BRAF mutation could represent an alternative mechanism of imatinib resistance. Kinase inhibitors targeting BRAF may be effective therapeutic options in this molecular GIST subset.     

Synchronous Metastatic Medullary and Papillary Thyroid Carcinomas in a Patient with Germline RET Mutation: Case Report,Molecular Analysis,and Implications for Pathogenesis

The occurrence of medullary thyroid carcinoma (MTC) in patients with germline RET mutation is well established, but the occasional occurrence of papillary thyroid carcinoma (PTC) in this setting remains unexplained. We report a case of synchronous MTC and PTC in a patient with germline RET mutation, and investigate the molecular pathogenesis of these two tumors. A 48-year-old man presented with cervical lymphadenopathy and was found to have metastatic MTC involving cervical and mediastinal lymph nodes. He underwent thyroidectomy and debulking of metastatic disease. The resected thyroid showed bilateral MTC and a 1-cm PTC. His lymph node metastases were predominantly MTC along with a small focus of metastatic PTC. Molecular testing using peripheral blood revealed a germline RET point mutation (Val804Met). Both tumors were analyzed for the BRAF (Val600Glu) mutation and the RET/PTC1 translocation. The PTC was positive for the BRAF mutation but negative for RET/PTC1. The MTC was negative for both abnormalities. We conclude that the MTC was caused by the germline RET mutation, while the PTC was caused by a somatic BRAF mutation. The occurrence of PTC in patients with germline RET mutations appears to be purely coincidental.     

Co‐occurrence of histone H3 K27M and BRAF V600E mutations in paediatric midline grade I ganglioglioma

Ganglioglioma (GG) is a grade I tumor characterized by alterations in the MAPK pathway, including BRAF V600E mutation. Recently, diffuse midline glioma with an H3 K27M mutation was added to the WHO 2016 classification as a new grade IV entity. As co‐occurrence of H3 K27M and BRAF V600E mutations has been reported in midline tumors and anaplastic GG, we searched for BRAF V600E and H3 K27M mutations in a series of 54 paediatric midline grade I GG (midline GG) to determine the frequency of double mutations and its relevance for prognosis. Twenty‐seven patients (50%) possessed the BRAF V600E mutation. The frequency of the co‐occurrence of H3F3A/BRAF mutations at diagnosis was 9.3%. No H3 K27M mutation was detected in the absence of the BRAF V600E mutation. Double‐immunostaining revealed that BRAF V600E and H3 K27M mutant proteins were present in both the glial and neuronal components. Immunopositivity for the BRAF V600E mutant protein correlated with BRAF mutation status as detected by massARRAY or digital droplet PCR. The median follow‐up of patients with double mutation was 4 years. One patient died of progressive disease 8 years after diagnosis, whereas the four other patients were all alive with stable disease at the last clinical follow‐up (at 9 months, 1 year and 7 years) without adjuvant therapy. We demonstrate in this first series of midline GGs that the H3 K27M mutation can occur in association with the BRAF V600E mutation in grade I glioneuronal tumors. Despite the presence of H3 K27M mutations, these cases should not be graded and treated as grade IV tumors because they have a better spontaneous outcome than classic diffuse midline H3 K27M‐mutant glioma. These data suggest that H3 K27M cannot be considered a specific hallmark of grade IV diffuse gliomas and highlight the importance of integrated histomolecular diagnosis in paediatric brain tumors.     

BRAF screening as a low-cost effective strategy for simplifying HNPCC genetic testing

Background: According to the international criteria for hereditary non-polyposis colorectal cancer (HNPCC) diagnostics, cancer patients with a family history or early onset of colorectal tumours showing high microsatellite instability (MSI-H) should receive genetic counselling and be offered testing for germline mutations in DNA repair genes, mainly MLH1 and MSH2. Recently, an oncogenic V600E hotspot mutation within BRAF, a kinase encoding gene from the RAS/RAF/MAPK pathway, has been found to be associated with sporadic MSI-H colon cancer, but its association with HNPCC remains to be further clarified.     

Alterations of the BRAF gene in thyroid tumors

BRAF belongs to the RAF family of protein kinases that are important components of the MAPK signaling pathway mediating cell growth, differentiation and survival. Activating point mutation of the BRAF gene resulting in V600E (previously designated as V599E) is a common event in thyroid papillary carcinoma, being found in approx 40% of this tumor. It has strong association with classical papillary carcinoma and tall cell and possibly Warthin-like variants. This mutation also occurs in thyroid poorly differentiated and anaplastic carcinomas, usually those containing areas of papillary carcinoma. Alterations in the BRAF gene do not overlap with RAS mutations and RET/PTC rearrangement, indicating that activation of one of the effectors of the MAPK pathway is sufficient for papillary thyroid carcinogenesis. Recently, another mechanism of BRAF activation has been identified, which involves chromosome 7q inversion that results in the AKAP9-BRAF fusion. It is rare in sporadic papillary carcinomas and is more common in tumors associated with radiation exposure. Yet another mechanism of BRAF activation may involve copy number gain, which is seen in a significant portion of thyroid follicular tumors of both conventional and oncocytic (Hürthle cell) types.     

Investigation of BRAF V600E detection approaches in papillary thyroid carcinoma

Objective

The detection of BRAF V600E mutation in papillary thyroid carcinoma (PTC) may be helpful to offer diagnostic confirmation. Additionally, such detection may provide a targeted therapeutic approach for the radioactive iodine resistant patients to predict adverse outcomes. To compare the results of immunohistochemistry (IHC) method using the anti-BRAF V600E (VE1) antibody with the Quantitative real-time polymerase chain reaction (qPCR) approach in examining BRAF V600E mutation in PTC, we investigated the sensitivity and specificity of BRAF V600E (clone VE1) mouse monoclonal antibody in detecting the BRAF V600E mutation and correlated BRAF V600E mutation with clinicopathologic features in PTC.

甲状腺乳头状癌中TROP-2表达的临床意义及其诊断价值

目的观察人类滋养层细胞表面抗原2(TROP-2)在甲状腺乳头状癌(papillary thyroid carcinoma,PTC)中的表达,探讨TROP-2在PTC中表达的临床意义及其诊断价值。方法采用免疫组化EnVision法检测100例甲状腺恶性病变(PTC 75例、滤泡性癌10例、髓样癌10例、差分化癌5例)、45例良性病变(正常甲状腺10例、结节性甲状腺肿10例、桥本甲状腺炎15例、滤泡性腺瘤10例),5例具有乳头样核特征的非浸润性甲状腺滤泡性肿瘤(non-invasive folliculaRthyroid neoplasms with papillary-like nucleaRfeatures,NIFTP)中TROP-2的表达;ARMS法检测PTC中BRAF V600E基因突变。分析TROP-2对PTC诊断的敏感性和特异性,及其与PTC临床病理特征以及BRAF V600E基因突变的关系。结果TROP-2在PTC中的阳性率为81.3%(61/75),在其他甲状腺恶性肿瘤和良性病变中均阴性,TROP-2对PTC诊断的敏感性为81.3%,特异性为100%。TROP-2表达与PTC淋巴结转移有关(P<0.05),与患者年龄、性别、肿瘤部位及临床分期无关(P>0.05),经典型PTC中TROP-2表达高于滤泡亚型PTC(P<0.05)。PTC中TROP-2表达与BRAF V600E基因突变呈正相关(P<0.05)。结论TROP-2是一种具有高度特异性和敏感性的诊断PTC的标志物,TROP-2检测可预测PTC的临床生物学行为和BRAF V600E基因突变状态,并对于形态学变形的PTC、微小型PTC和PTC的甲状腺内扩散的诊断和识别具有重要价值。     

BRAF V600E Mutation Is Associated with mTOR Signaling Activation in Glioneuronal Tumors

BRAF V600E mutations have been recently reported in glioneuronal tumors (GNTs). To evaluate the expression of the BRAF V600E mutated protein and its association with activation of the mammalian target of rapamycin (mTOR) pathway, immunophenotype and clinical characteristics in GNTs, we investigated a cohort of 174 GNTs. The presence of BRAF V600E mutations was detected by direct DNA sequencing and BRAF V600E immunohistochemical detection. Expression of BRAF‐mutated protein was detected in 38/93 (40.8%) gangliogliomas (GGs), 2/4 (50%) desmoplastic infantile gangliogliomas (DIGs) and 23/77 (29.8%) dysembryoplastic neuroepithelial tumors (DNTs) by immunohistochemistry. In both GGs and DNTs, the presence of BRAF V600E mutation was significantly associated with the expression of CD34, phosphorylated ribosomal S6 protein (pS6; marker of mTOR pathway activation) in dysplastic neurons and synaptophysin (P < 0.05). In GGs, the presence of lymphocytic cuffs was more frequent in BRAF‐mutated cases (31 vs. 15.8%; P = 0.001). The expression of both BRAF V600E and pS6 was associated with a worse postoperative seizure outcome in GNT (P < 0.001). Immunohistochemical detection of BRAF V600E‐mutated protein may be valuable in the diagnostic evaluation of these glioneuronal lesions and the observed association with mTOR activation may aid in the development of targeted treatment involving specific pathogenic pathways.     

分化型甲状腺癌中BRAF V600E突变分析

目的探讨分化型甲状腺癌中BRAF V600E突变与临床病理特征的关系。方法收集甲状腺乳头状癌(papillary thyroid carcinoma,PTC)80例(其中经典型67例、滤泡亚型8例、嗜酸细胞亚型3例、高细胞亚型2例)、滤泡癌5例,其中30例PTC取相应癌旁组织,全部送基因检测室检测BRAF V600E突变情况。结果 80例PTC中BRAF V600E突变率为65.0%,5例滤泡癌及30例癌旁组织中未发现BRAF V600E突变;BRAF V600E突变与患者年龄、肿瘤包膜侵犯、淋巴结转移及TNM分期有关。PTC亚型中,经典型和高细胞亚型的BRAF V600E突变率较高(70.1%、100.0%),滤泡亚型的突变率较低(33.3%)。结论PTC中BRAF V600E突变可能与患者年龄有一定相关性,还与包膜侵犯、淋巴结转移及TNM分期有关,经典型和高细胞亚型的BRAF V600E突变率较高,明显高于滤泡亚型。     

Effect of BRAF V600E mutation detection of fine-needle aspiration biopsy on diagnosis and treatment guidance of papillary thyroid carcinoma

ObjectiveThe aim of this study was to evaluate the diagnostic value of detection of BRAF V600E mutation in the fine-needle aspiration cytology (FNAC) specimens of thyroid nodules and the relationship between BRAF V600E mutation and the clinicopathological characteristics of papillary thyroid carcinoma (PTC).MethodsA total of 252 patients who underwent initial thyroid surgery were retrospectively analysed. All the patients underwent a preoperative FNAC at our institution, and the thyroid puncture cell fluid was used for both the cytological diagnosis and BRAF V600E mutational analysis using quantitative polymerase chain reaction. The Cochran-Mantel-Haenszel test was used to evaluate the diagnostic value of BRAF V600E mutation in FNAC fluid in diagnosing PTC. The association between BRAF V600E mutation and the clinicopathological parameters of PTC was analysed using the χ² test.ResultsThrough FNAC, 21 (8%), 60 (24%), and 171 (68%) cases were cytologically diagnosed as benign, indeterminate, and malignant, respectively. Postoperatively, 242 cases were histopathologically diagnosed as PTCs and 10 as goitre nodules. In the FNAC samples, 12 (57 %) of the 21 benign, 48 (80 %) of the 60 indeterminate, and 152 (88.9 %) of the 171 malignant cases showed BRAF V600E mutation. The histopathological diagnosis was used as the gold standard. The sensitivity and specificity of BRAF V600E mutational analysis in the FNAC samples for the diagnosis of PTC were 91.7 % and 100 % in benign, 82.8 % and 100 % in the indeterminate, and 89.4 % and 100 % in the malignant cases, respectively.ConclusionBRAF V600E mutational analysis in FNAC samples of thyroid nodules can be used an effective supplementary diagnostic method at our institution. However, BRAF V600E mutation was not associated with aggressive characteristics in PTC.