Project description:To study the very early changes in high-grade transformation of gastrointestinal stromal tumors (GISTs), 17 biphasic GISTs, with a transitional status in which low-grade and high-grade parts coexist, were collected from 263 continuous cases (6.5%). Nucleic acids of each part were retrieved for gene expression profiling.
Project description:Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the digestive tract. The majority of GIST patients eventually develop resistance to imatinib therapy. To identify the responsible mechanisms, we investigated the differentially expressed mRNAs and circRNAs in imatinib-resistant GISTs using SBC ceRNA microarrays. We found that 107 mRNAs and 521 circRNAs were significantly differentially expressed between imatinib-naïve and imatinib-resistant GIST tissue samples. qRT-PCR analyses validated that circ-BRIP1, circ-EPHB4 and circ-RECQL4 and their host genes were upregulated in imatinib-resistant GISTs, and circ-BRIP1, circ-EPHB4, and RECQL4 were associated with imatinib resistance, tumor relapse and progression, and metastasis in GIST patients. The expression levels of circ-BRIP1, circ-EPHB4 and their host genes were also evaluated using TMAs with 150 human GISTs. The expression level of EPHB4 was significantly increased in high-grade GISTs in comparison to low-grade GISTs and correlated with imatinib resistance. Specifically, we first developed a method for high-throughput analysis of the expression of differentially expressed circRNAs by ISH-IHC in a set of FFPE-tissue microarrays in GIST. Our results also suggested a possible role for circ-BRIP1, circ-EPHB4, and their host genes in the progression of GISTs.
Project description:In contrast to the paucity of clinic GIST (Gastrointestinal stromal tumor; 0.0014 % happening rate), there is a more than twenty thousand times higher rate for miniGISTs, about ~30% of human population could be identified to have miniGISTs. Exploring the molecular differences between miniGISTs and overt GISTs will help us to understand the transformation mechanisms along with GIST progression, but C-kit and PDGFRA mutations analysis failed to identify the differences between these two groups. Conclusion: miniGISTs have significant distinct gene expression profile with overt GISTs by both unsupervised and supervised analysis. Our finding indicated that c-kit and DOG1 expression are the very early events in the genesis of miniGIST and overt GIST, and miniGIST is a molecular distinct group with overt GIST. Within our study, we collected six miniGISTs with diameter less than 1cm from autopsies and seven overt GISTs from clinic, performed the first system-wide gene expression profiling of miniGISTs and overt GISTs by 3’end RNA Sequencing, and further compared the expression profiles between these two groups.
Project description:In contrast to the paucity of clinic GIST (Gastrointestinal stromal tumor; 0.0014 % happening rate), there is a more than twenty thousand times higher rate for miniGISTs, about ~30% of human population could be identified to have miniGISTs. Exploring the molecular differences between miniGISTs and overt GISTs will help us to understand the transformation mechanisms along with GIST progression, but C-kit and PDGFRA mutations analysis failed to identify the differences between these two groups. Conclusion: miniGISTs have significant distinct gene expression profile with overt GISTs by both unsupervised and supervised analysis. Our finding indicated that c-kit and DOG1 expression are the very early events in the genesis of miniGIST and overt GIST, and miniGIST is a molecular distinct group with overt GIST.
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: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:Activating mutation of KIT is well known as a key molecular event for the development of gastrointestinal stromal tumors(GISTs). Dysregulation of microRNAs(miRNA) might elucidate KIT mutation, KIT overexpression and the resulting tumorigenesis in GIST. Herein we identified miRNA expression profiles that associated with KIT mutation and KIT overexpression in GIST by miRNA microarrays and Real-time PCR in GISTs. The potentially target genes of selected miRNAs were analyzed by bioinformatic techniques with GO and KEGG pathway analysis. We showed that 6 miRNAs were differentially expressed in CD117IHC+/KITmutant GISTs compared to CD117IHC-/wild-type GISTs. Of these, 2 miRNAs including miR-483-3p and miR-589 were up-regulated, while the other 4 miRNAs including miR-140-5p, miR-148b-3p, miR-1587 and miR-4507 were down-regulated. GO and KEGG analysis demonstrated that miRNAs with significant change were involved in regulation of target genes related to the development of GIST. Among the candidate miRNAs studied, miR-148b-3p and miR-140-5p may be involved in GIST tumorigenesis via targeting mutant KIT or via intermediate molecules of PDGFRA, PI3K-AKT and MAPK pathway, such as AKT2, MAPK1, MAPK10, STAT5A, SMAD4, SMAD5 and PTEN. Furthermore, the reduced expression of miR-140-5p and miR-148b-3p were inversely correlated with high-risk grade, recurrence and metastasis of GIST. The current findings indicated that miR-148b-3p and miR-140-5p were not only involved in tumorigenesis of GIST, but might also participate in the progression of GIST and could be considered as novel biomarkers for potentially predicting the prognosis of GIST.
Project description:KIT, PDGFRA, NF1, and SDH mutations are alternate initiating events, fostering hyperplasia in gastrointestinal stromal tumors (GISTs), and additional genetic alterations are required for progression to malignancy. The most frequent secondary alteration, demonstrated in ~70% of GISTs, is chromosome 14q deletion. Here we report hemizygous or homozygous inactivating mutations of the chromosome 14q MAX gene in 16 of 76 GISTs (21%). We find MAX mutations in 17% and 50% of sporadic and NF1-syndromic GISTs, respectively, and we find loss of MAX protein expression in 48% and 90% of sporadic and NF1-syndromic GISTs, and in 3 of 8 micro GISTs, which are early GISTs. MAX genomic inactivation is associated with p16 silencing in the absence of p16 coding sequence deletion, and MAX induction restores p16 expression and inhibits GIST proliferation. Hence, MAX inactivation is a common event in GIST progression, fostering cell cycle activity in early GISTs.
Project description:To clarify the microRNA (miRNA) expression signatures in gastrointestinal stromal tumors (GISTs), a series of 32 GIST specimens were analyzed using Agilent miRNA microarray V3. Unsupervised hierarchical clustering revealed that GISTs can be categorized into 2 groups according to the expression of a miRNA cluster encoded on chromosome 14q32.31. Total RNA was extracted from 32 fresh frozen GIST specimens obtained from surgical resections. Expression of 851 miRNAs was analyzed using Human miRNA Microarray V3 (Rel 12.0 G4470C; Agilent technologies, Santa Clara, CA, USA). Risk grade was assessed according to the risk definition system proposed by Fletcher et al. (Hum Pathol. 2002;33:459-65.)
Project description:To analyze the gene expression signatures in gastrointestinal stromal tumors (GISTs), a series of 14 GIST specimens were analyzed using Agilent Whole Human Genome Microarray (4x44K, G4112F). Total RNA was extracted from 32 fresh frozen GIST specimens obtained from surgical resections. Gene expression was analyzed using Agilent Whole Human Genome Microarray (4x44K, G4112F, Agilent technologies, Santa Clara, CA, USA). Risk grade was assessed according to the risk definition system proposed by Fletcher et al. (Hum Pathol. 2002;33:459-65.)