Project description:Gastrointestinal stromal tumors (GISTs) are the most important mesenchymal tumors of the gastrointestinal tract. The vast majority of GISTs exhibit activating mutations of KIT or PDGFRA, but epigenetic alteration of GISTs is largely unknown. In this study, we aimed to clarify the involvement of DNA methylation in GIST malignancy. A total of 25 GIST specimens were studied using Human Genome CGH Microarray Kit 105A (G4412A, Agilent). Levels of LINE-1 methylation were analyzed using bisulfite-pyrosequencing. LINE-1 hypomethylation was correlated with risk grade, and high-risk GISTs exhibited lower levels of LINE-1 methylation than low- or intermediate-risk GISTs. Array CGH analysis revealed a significant correlation between LINE-1 hypomethylation and chromosomal aberrations. Our data suggest that LINE-1 hypomethylation correlates with the aggressiveness of GISTs. Hypomethylation may increase the malignant potential of GISTs by inducing accumulation of chromosomal aberrations. A total of 25 surgically obtained human gastrointestinal stromal tumors (GISTs) was analyzed using Agilent CGH microarray. Copy number aberration was compared with clinicopathological features and DNA methylation status.
Project description:Gastrointestinal stromal tumors (GISTs) are the most important mesenchymal tumors of the gastrointestinal tract. The vast majority of GISTs exhibit activating mutations of KIT or PDGFRA, but epigenetic alteration of GISTs is largely unknown. In this study, we aimed to clarify the involvement of DNA methylation in GIST malignancy. A total of 25 GIST specimens were studied using Human Genome CGH Microarray Kit 105A (G4412A, Agilent). Levels of LINE-1 methylation were analyzed using bisulfite-pyrosequencing. LINE-1 hypomethylation was correlated with risk grade, and high-risk GISTs exhibited lower levels of LINE-1 methylation than low- or intermediate-risk GISTs. Array CGH analysis revealed a significant correlation between LINE-1 hypomethylation and chromosomal aberrations. Our data suggest that LINE-1 hypomethylation correlates with the aggressiveness of GISTs. Hypomethylation may increase the malignant potential of GISTs by inducing accumulation of chromosomal aberrations.
Project description:To explore mechanisms underlying wild-type GISTs, array CGH was performed on 32 gastric GISTs (4 risk groups stratified by tumor size and mitotic counts comprised 8 cases each).
Project description:Gastrointestinal stromal tumors (GISTs) comprise a biologically diverse group of neoplasms with respect to activating mutations in either KIT or PDGFRA genes, histology, anatomic site of origin, and clinical aggressiveness. In this study, we applied the high resolution array-based comparative genomic hybridization (array-CGH) technology to 66 primary GISTs (40 gastric and 26 non-gastric, 48 with KIT- and 18 with PDGFRA-mutations) for identification of novel high-level alterations and for characterization of genotype-related genomic changes. All cases had genomic imbalances with the highest occurrence of chromosome 14q (73%), 1p (62%), 22q (59%), 15q (38%) and 13q (29%) losses. Our data indicate that loss of chromosome 14 and/or 22 is an early change in GIST tumorigenesis irrespective of tumor genotype. Furthermore, DNA copy number changes showed a site dependent pattern. These included lower incidence of losses at 14q (87% vs. 35%), and higher frequency of losses at 1p (45%, vs. 85%) and 15q (17% vs. 69%) in non-gastric versus gastric site (p<0.001 for all). However, in the multivariate analysis with adjustment to tumor risk stratification, only the chromosome 14q loss site-dependent pattern of distribution retained its significance. These findings suggest that loss of chromosome 14q is a relatively late genetic event in the development of non-gastric GISTs, the lack of which is most likely substituted by the accumulation of chromosomes 1p/15q and other changes. The novel minimal overlapping regions of deletion at chromosome 1p (1p36.32-1p35.2, 1p34.1, and 1p22.1-1p21.3), 13q (13q14.11-q14.2 and 13q32.3-q33.1) and 15q23 were delineated, which point to chromosomal regions that may harbor genes relevant to the development of these neoplasms. Keywords: comparative genomic hybridization, genotype, site dependent changes