Dataset Information

Identification of a Recurrent LMO7-BRAF Fusion in Papillary Thyroid Carcinoma.

ABSTRACT: BACKGROUND:The BRAFV600E mutation is the most common driver in papillary thyroid carcinoma (PTC) tumors. In recent years, gene fusions have also been recognized as important drivers of cancer in PTC. Previous studies have suggested that thyroid tumors with fusion genes frequently display an aggressive course. These observations prompted further exploration of gene fusions in PTC tumors. The aim was to search for previously unrecognized gene fusions using thyroid tissue samples from PTC patients. METHODS:Gene fusions were analyzed in RNA sequencing data obtained from 12 PTC tumors and paired unaffected thyroid tissue samples. Candidate fusions were further filtered and validated using reverse transcriptase polymerase chain reaction, Sanger sequencing, and fluorescence in situ hybridization. An Ohio cohort of 148 PTC tumor samples was screened for a LMO7-BRAF fusion and the BRAFV600E mutation. Functional assays were performed to assess the LMO7-BRAF fusion. RESULTS:Two coding fusions (CCDC6-RET and LMO7-BRAF) were found in one tumor sample each. The novel LMO7-BRAF fusion was validated by reverse transcriptase polymerase chain reaction and fluorescence in situ hybridization. The LMO7-BRAF fusion was a recurrent somatic alteration with a frequency of 2.0% (3/148) in PTC tumors, while the BRAFV600E point mutation was found in 63.5% (94/148) of tumors. Enforced expression of LMO7-BRAF fusion protein stimulated endogenous ERK1/2 phosphorylation and promoted anchorage independent cell growth to an extent similar to BRAFV600E. CONCLUSIONS:A novel fusion gene, LMO7-BRAF, was identified in PTC tumors. The results indicate that the LMO7-BRAF fusion behaves as an oncogenic alteration. This observation expands the spectrum of fusion genes involving kinases in thyroid cancer.

SUBMITTER: He H

PROVIDER: S-EPMC5994666 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature

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Identification of a Recurrent LMO7-BRAF Fusion in Papillary Thyroid Carcinoma.

He Huiling H Li Wei W Yan Pearlly P Bundschuh Ralf R Killian Jackson A JA Labanowska Jadwiga J Brock Pamela P Shen Rulong R Heerema Nyla A NA de la Chapelle Albert A

Thyroid : official journal of the American Thyroid Association 20180516 6

<h4>Background</h4>The BRAF<sup>V600E</sup> mutation is the most common driver in papillary thyroid carcinoma (PTC) tumors. In recent years, gene fusions have also been recognized as important drivers of cancer in PTC. Previous studies have suggested that thyroid tumors with fusion genes frequently display an aggressive course. These observations prompted further exploration of gene fusions in PTC tumors. The aim was to search for previously unrecognized gene fusions using thyroid tissue samples ...[more]

PMID: 29768105

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Project description:ContextThe BRAF V600E mutation (BRAF-MUT) confers an aggressive phenotype in papillary thyroid carcinoma, but unidentified additional genomic abnormalities may be required for full phenotypic expression.ObjectiveRNA sequencing (RNA-Seq) was performed to identify genes differentially expressed between BRAF-MUT and BRAF wild-type (BRAF-WT) tumors and to correlate changes to patient clinical status.DesignBRAF-MUT and BRAF-WT tumors were identified in patients with T1N0 and T2-3N1 tumors evaluated in a referral medical center. Gene expression levels were determined (RNA-Seq) and fusion transcripts were detected. Multiplexed capture/detection and digital counting of mRNA transcripts (nCounter, NanoString Technologies) validated RNA-Seq data for immune system-related genes.PatientsBRAF-MUT patients included nine women, three men; nine were TNM stage I and three were stage III. Three (25%) had tumor infiltrating lymphocytes. BRAF-WT included five women, three men; all were stage I, and five (62.5%) had tumor infiltrating lymphocytes.ResultsRNA-Seq identified 560 of 13 085 genes differentially expressed between BRAF-MUT and BRAF-WT tumors. Approximately 10% of these genes were related to MetaCore immune function pathways; 51 were underexpressed in BRAF-MUT tumors, whereas 4 (HLAG, CXCL14, TIMP1, IL1RAP) were overexpressed. The four most differentially overexpressed immune genes in BRAF-WT tumors (IL1B; CCL19; CCL21; CXCR4) correlated with lymphocyte infiltration. nCounter confirmed the RNA-Seq expression level data. Eleven different high-confidence fusion transcripts were detected (four interchromosomal; seven intrachromosomal) in 13 of 20 tumors. All in-frame fusions were validated by RT-PCR.ConclusionBRAF-MUT papillary thyroid cancers have reduced expression of immune/inflammatory response genes compared with BRAF-WT tumors and correlate with lymphocyte infiltration. In contrast, HLA-G and CXCL14 are overexpressed in BRAF-MUT tumors. Sixty-five percent of tumors had between one and three fusion transcripts. Functional studies will be required to determine the potential role of these newly identified genomic abnormalities in contributing to the aggressiveness of BRAF-MUT and BRAF-WT tumors.

Project description:BackgroundOver the past ten years, the incidence rate of papillary thyroid carcinoma (PTC) worldwide has been increasing rapidly year by year, with the incidence rate increasing 6% annually. PTC has become the malignant tumor with the highest growth rate in the world that fourteen PTC-related mutant genes have been identified. Whether the BRAFV600E mutation related to more aggressive clinicopathologic features and worse outcome in PTC remains variable and controversial. We aim to investigate the risk factors that may predict the BRAFV600E mutation potential of these lesions and new prevention strategies in PTC patients.MethodsA total of 9,908 papillary thyroid carcinoma patients with average 74.6% BRAFV600E mutations were analyzed (RevMan 5.3 software) in this study. The PubMed, Embase, and ISI Web of Science databases were systematically searched for works published through December 15, 2021.ResultsThe following variables were associated with an increased risk of BRAFV600E mutation in PTC patients: age ≥ 45 years (OR = 1.39, 95%CI = 1.21-1.60, p < 0.00001), male gender (OR = 1.13, 95%CI = 0.99-1.28, p = 0.06), multifocality (OR = 1.22, 95%CI = 1.07-1.40, p = 0.004), lymph node metastasis (OR = 1.33, 95%CI = 0.79-2.23, p = 0.28), extrathyroidal extension + (OR = 1.61, 95%CI = 1.06-2.44, p = 0.03), vascular invasion + (OR = 2.04, 95%CI = 1.32-3.15, p = 0.001), and tumor node metastasis stage (OR = 1.61, 95%CI = 1.38-1.88, p < 0.00001). In addition, tumor size (>1 cm) (OR = 0.51, 95%CI = 0.32-0.81, p = 0.005) and distant metastasis (OR = 0.69, 95%CI = 0.22-2.21, p = 0.54) had no association or risk with BRAFV600E mutation in PTC patients.ConclusionOur systematic review identified the following significant risk factors of BRAFV600E mutation in PTC patients: age (≥45 years), gender (male), multifocality, lymph node metastasis, vascular invasion, extrathyroidal extension, and advanced tumor node metastasis stage (stages III and IV). Tumor size (>1 cm) and distant metastasis do not appear to be correlated with BRAFV600E mutation in PTC patients.

Dataset Information

Identification of a Recurrent LMO7-BRAF Fusion in Papillary Thyroid Carcinoma.

Publications

Identification of a Recurrent LMO7-BRAF Fusion in Papillary Thyroid Carcinoma.

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