Project description:We performed miRNA expression profiling in a series of fresh-frozen neoadjuvantly imatinib treated gastrointestinal stromal tumors (GIST), using a microarray approach. Significant differentially expressed miRNAs among imatinib-resistant and imatinib-sensitive groups were identified using SAM analysis.
Project description:Despite the success of imatinib in advanced gastrointestinal stromal tumor (GIST) patients, 50% of the patients experience resistance within two years of treatment underscoring the need to get better insight into the mechanisms conferring imatinib resistance. Here the microRNA and mRNA expression profiles in primary (imatinib-naïve) and imatinib-resistant GIST were examined. Fifty-three GIST samples harboring primary KIT mutations (exon 9; n=11/exon 11; n=41/exon 17; n=1) and comprising imatinib-naïve (IM-n) (n=33) and imatinib-resistant (IM-r) (n=20) tumors, were analyzed. The microRNA expression profiles were determined and from a subset (IM-n, n=14; IM-r, n=15) the mRNA expression profile was established. Ingenuity pathway analyses were used to unravel biochemical pathways and gene networks in IM-r GIST. Thirty-five differentially expressed miRNAs between IM-n and IM-r GIST samples were identified. Additionally, miRNAs distinguished IM-r samples with and without secondary KIT mutations. Furthermore 352 aberrantly expressed genes were found in IM-r samples. Pathway and network analyses revealed an association of differentially expressed genes with cell cycle progression and cellular proliferation thereby implicating genes and pathways involved in imatinib resistance in GIST. Differentially expressed miRNAs and mRNAs between IM-n and IM-r GIST were identified. Bioinformatic analyses provided insight into the genes and biochemical pathways involved in imatinib-resistance and highlighted key genes that may be putative treatment targets.
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:We performed miRNA expression profiling in a series of fresh-frozen neoadjuvantly imatinib treated gastrointestinal stromal tumors (GIST), using a microarray approach. Significant differentially expressed miRNAs among imatinib-resistant and imatinib-sensitive groups were identified using SAM analysis. Agilent microarray platform with probes matching 903 human miRNAs was used to determine miRNA expression profiles in 17 GISTs (imatinib-sensitive and 7 imatinib-resistant). To validate the microarray platform, the expression levels of selected miRNAs were evaluated using qRT-PCR.
Project description:Purpose: The goals of this study are to characterize the transcriptional dysregulation of GIST. More importantly, the transcriptome differences betweeen Imatinib-sensitive and resistant patients are compared to identify RNAs that may impact Imatinib resistance. Methods: High-throughput RNA sequencing (RNA-seq) was employed to capture the transcriptional changes in GIST compared to normal samples. RSEM was used to quantify gene expression and DESeq2 was utilized to compared expression changes between different sample groups.
Project description:Analysis of mouse GIST tumors at the gene expression level. The purpose of the study was to identify immunomodulatory genes in mouse GIST tumors after in vivo treatment with the specific tyrosine kinase inhibitor imatinib mesylate. Total RNA obtained from mouse GIST tumors after in vivo treatment with imatinib or vehicle control injected intraperitoneally.
Project description:Analysis of mouse GIST tumors at the gene expression level. The purpose of the study was to identify immunomodulatory genes in mouse GIST tumors after in vivo treatment with the specific tyrosine kinase inhibitor imatinib mesylate.
Project description:Activating mutations in either KIT or PDGFRA are present in approximately 90% of gastrointestinal stromal tumors (GISTs). Although treatment with the KIT and PDGFR inhibitor imatinib can control advanced disease in about 80% of GIST patients, the beneficial effect is not durable. Here, we report that ligands from the FGF family reduced the effectiveness of imatinib in GIST cells, and FGF2 and FGFR1 are highly expressed in all primary GIST samples examined. The combination of KIT and FGFR inhibition showed increased growth inhibition in imatinib-sensitive GIST cell lines in the presence or absence of added FGF2 in vitro, and delayed tumor regrowth in vivo. In addition, inhibition of mitogen-activated protein kinase (MAPK) signaling by imatinib was not sustained in GIST cells. An extracellular signal-regulated kinase (ERK) rebound occurred through activation of FGF signaling, and was repressed by FGFR1 inhibition. Downregultation of Sprouty proteins played a role in the imatinib-induced feedback activation of FGF signaling in GIST cells. We used micorarrays to quantify the gene expression levels in GIST cell lines.
Project description:We performed microRNA expression profiling in a series of fresh-frozen neoadjuvantly imatinib-treated and non-treated gastrointestinal stromal tumors (GIST), using a microarray approach. Significant differentially expressed microRNAs among imatinib-treated and non-treated groups were identified using SAM analysis.
Project description:This study is an open-label, multicenter, Phase I dose-escalation study of the combination of AMN107 and imatinib (STI571) in patients with imatinib-resistant GIST. This study is designed to determine the Phase II dose of AMN107 and imatinib when administered together in patients with imatinib-resistant GIST, and to characterize the safety, tolerability and pharmacokinetic (PK) profile of this combination.
