Novel clinically relevant genes in gastrointestinal stromal tumors identified by exome sequencing.
OBJECTIVE
Chromosomal gains and losses resulting in altered gene dosage are known to be recurrent in gastrointestinal stromal tumors (GIST). The aim of our study was the identification of clinical relevant genes in these candidate regions.


METHODS
A cohort of 174 GIST was investigated using DNA array (n = 29), FISH (n = 125), exome sequencing (n = 13), and immunohistochemistry (n = 145).


RESULTS
Array analysis revealed recurrent copy number variations (CNVs) of chromosomal arms 1p, 1q, 3p, 4q, 5q, 7p, 11q, 12p, 13q, 14q, 15q, and 22q. FISH studies of these CNVs showed that relative loss of 1p was associated with shorter disease-free survival (DFS). Analysis of exome sequencing concentrating on target regions showing recurrent CNVs revealed a median number of 3,404 (range 1,641-13,602) variants (SNPs, insertions, deletions) in each tumor minus paired blood sample; variants in at least three samples were observed in 37 genes. After further analysis, target genes were reduced to 10 in addition to KIT and PDGFRA. Immunohistochemical investigation showed that expression of SYNE2 and DIAPH1 was associated with shorter DFS, expression of RAD54L2 with shorter and expression of KIT with longer overall survival.


CONCLUSIONS
Using a novel approach combining DNA arrays, exome sequencing, and immunohistochemistry, we were able to identify 10 target genes in GIST, of which three showed hithero unknown clinical relevance. Because the identified target genes SYNE2, MAPK8IP2, and DIAPH1 have been shown to be involved in MAP kinase signaling, our data further indicate the important role of this pathway in GIST.
Authors' Affiliations: Department of Surgery; Center for Medical Statistics, Informatics, and Intelligent Systems; Department of Obstetrics and Gynecology and Core Unit Next Generation Sequencing; Clinical Institute of Pathology, Medical University of Vienna; and Center for Integrative Bioinformatics Vienna (CIBIV), Max F Perutz Laboratories, University of Vienna & Medical University of Vienna, & Faculty of Computer Science, University of Vienna, Vienna, Austria.
Sebastian F
SF
Schoppmann
Ursula
U
Vinatzer
Niko
N
Popitsch
Martina
M
Mittlböck
Sandra
S
Liebmann-Reindl
Gerd
G
Jomrich
Berthold
B
Streubel
Peter
P
Birner
D014408:Biomarkers, Tumor / Q000235:genetics*; D056915:DNA Copy Number Variations; D059472:Exome; D046152:Gastrointestinal Stromal Tumors / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D020869:Gene Expression Profiling; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D009367:Neoplasm Staging; D011379:Prognosis
D014408:Biomarkers, Tumor