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Deep Sequencing Identifies Multiple Fusion Transcripts, Differentially Expressed Genes, and Generalized Immune Suppression in BRAF (V600E) mutant vs. BRAF wild-type Papillary Thyroid Carcinoma

ABSTRACT: CONTEXT: BRAF V600E mutation (BRAF-mut.) confers aggressiveness in papillary thyroid carcinoma, but unidentified genomic abnormalities may be required for full phenotypic expression. OBJECTIVE: To perform deep sequencing to identify genes differentially expressed between BRAF-mut. and BRAF-wild-type (BRAF-WT) tumors, and to compare to patient clinical status. DESIGN: BRAF-mut. and BRAF-WT tumors were identified in patients with T1N0 and with T23N1 tumors. Expression levels of genes were determined from RNA sequencing (RNA-Seq) data and fusion transcripts were detected. NanoString was used to validate the RNA-Seq data for immune genes. SETTING: Patients were seen at two sites of a major referral medical center. PATIENTS: Twenty patients were studied. BRAF-mut. patients included 9 women, 3 men; 9 were TNM stage I and 3 were stage III; 3 (25%) had lymphocytic thyroiditis. BRAF-WT included 5 women; 3 men; all were stage I; 5 (62.5%) had lymphocytic thyroiditis. RESULTS: 560 of 13,085 genes were differentially expressed by RNA-Seq, and MetaCore analysis identified 55 immune function genes that were differentially expressed as a function of BRAF mutational status. Immune function genes were broadly underexpressed in BRAF-mut. tumors, with only 4 genes (HLA-G, CXCL14, TIMP1, IL1RAP) more highly expressed. NanoString validated the RNA Seq data for immune genes. Eleven high confidence fusion transcripts were detected, four being inter-chromosomal and seven intra-chromosomal. CONCLUSION: BRAF-mut. papillary thyroid cancers have less expression of immune and inflammatory response genes than BRAF-WT tumors. Thirteen of 20 (65%) tumors had between one and three fusion transcripts. Functional studies will be required to determine the potential role of the newly identified genomic abnormalities in contributing to the aggressiveness of BRAF-mut. and wild-type tumors.

ORGANISM(S): Homo sapiens

PROVIDER: GSE48953 | GEO | 2015/07/01

SECONDARY ACCESSION(S): PRJNA212391

REPOSITORIES: GEO

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Project description:Low-grade ovarian serous carcinomas are believed to arise via an adenoma-serous borderline tumor-serous carcinoma sequence. In this study, we found that advanced-stage, low-grade ovarian serous carcinomas both with and without adjacent serous borderline tumor shared similar regions of loss of heterozygosity. We then analyzed 91 ovarian tumor samples for mutations in TP53, BRAF, and KRAS. TP53 mutations were not detected in any serous borderline tumors (n = 30) or low-grade serous carcinomas (n = 43) but were found in 73% of high-grade serous carcinomas (n = 18). BRAF (n = 9) or KRAS (n = 5) mutation was detected in 47% of serous borderline tumors, but among the low-grade serous carcinomas (39 stage III, 2 stage II, and 2 stage I), only one (2%) had a BRAF mutation and eight (19%) had a KRAS mutation. The low frequency of BRAF mutations in advanced-stage, low-grade serous carcinomas, which contrasts with previous findings, suggests that aggressive, low-grade serous carcinomas are more likely derived from serous borderline tumors without BRAF mutation. In addition, advanced-stage, low-grade carcinoma patients with BRAF or KRAS mutation have a better apparent clinical outcome. However, further investigation is needed. Low-grade ovarian serous carcinomas are believed to arise via an adenoma-serous borderline tumor-serous carcinoma sequence. In this study, we found that advanced-stage, low-grade ovarian serous carcinomas both with and without adjacent serous borderline tumor shared similar regions of loss of heterozygosity. We then analyzed 91 ovarian tumor samples for mutations in TP53, BRAF, and KRAS. TP53 mutations were not detected in any serous borderline tumors (n = 30) or low-grade serous carcinomas (n = 43) but were found in 73% of high-grade serous carcinomas (n = 18). BRAF (n = 9) or KRAS (n = 5) mutation was detected in 47% of serous borderline tumors, but among the low-grade serous carcinomas (39 stage III, 2 stage II, and 2 stage I), only one (2%) had a BRAF mutation and eight (19%) had a KRAS mutation. The low frequency of BRAF mutations in advanced-stage, low-grade serous carcinomas, which contrasts with previous findings, suggests that aggressive, low-grade serous carcinomas are more likely derived from serous borderline tumors without BRAF mutation. In addition, advanced-stage, low-grade carcinoma patients with BRAF or KRAS mutation have a better apparent clinical outcome. However, further investigation is needed. Gene expression analysis was performed on five serous borderline tumors with BRAF mutation and five serous borderline tumors without BRAF mutation randomly. RNA was extracted from microdissected tumor cells. Expression profiling was carried out with Affymetrix GeneChip Human Genome U133 Plus 2.0 arrays

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Deep Sequencing Identifies Multiple Fusion Transcripts, Differentially Expressed Genes, and Generalized Immune Suppression in BRAF (V600E) mutant vs. BRAF wild-type Papillary Thyroid Carcinoma

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