MET Amplified Gastric Cancer Cell Lines +/- Crizotinib
ABSTRACT: MET amplification is present in 20% of gastric cancers and has been confirmed as a therapeutic target in clinical trials. The molecular mechanisms of response and resistance to MET inhibitors are not well understood. We investigated the determinants of MET dependency in human gastric cancer. MET inhibition inhibited proliferation and induced cell death only in MET-amplified gastric cancer cell lines. The effects on growth arrest were stronger than the effects on cell death. To identify possible resistance mechanisms, we performed whole-genome mRNA expression profiling. Molecular changes related to autophagy were among the top alterations observed. Consistent with these findings, autophagy levels increased in a concentration-dependent manner when MET-amplified cells were exposed to crizotinib. Autophagy inhibition caused a dramatic decrease in apoptosis in one of the MET-amplified cell lines (MKN45) but not in the other (SNU-5). Because autophagy may provide energy in cells subjected to growth factor deprivation, we explored the effects of MET or autophagy inhibition on cellular ATP levels. This revealed that autophagy-dependent ATP production was selectively required for apoptosis in the MKN45 cells and that chemical ATP depletion mimicked the effects of autophagy inhibition to block cell death. Overall, the data reveal a novel relationship between ATP depletion and resistance to MET inhibitor-induced cell death. Our observations suggest that autophagy inhibitors could have unintended consequences when they are combined with growth factor receptor inhibitors in tumors that require autophagy-dependent ATP production for apoptosis. 12 samples triplicate samples of SNU-5 and MKN45 +/- criztonib for 24 hours
Project description:Amplification and activation of the Met receptor tyrosine kinase occurs up to 23% of gastric cancers, suggesting that Met is a therapeutic target in these cancers. However, the steady-state signaling events that occur during chronic Met activation, and mechanisms for resistance to Met small-molecule inhibitors, are poorly understood. Here we show that multiple gastric cancer cell lines harboring MET amplifications are dependent on Met signaling for proliferation and anchorage-independent growth. In these cells, short-term inhibition of Met leads to coordinated changes in gene expression; these include a rapid loss in expression of immediate-early genes, followed by decreased expression of genes involved in cell cycle and proliferation. Activation of Ras-Erk, PI3K-Akt and STAT3 pathways is attenuated by acute Met inhibition. STAT3 inhibition alone, but not individual inhibition of Mek or Akt, is sufficient to abrogate Met-dependent growth of these cells. However, following chronic Met inhibition, reactivation of Mek-dependent Erk phosphorylation occurs even in the presence of Met inhibitor corresponding with a downregulation of Erk negative regulators DUSP4/6. This provides a mechanism for the emergence of drug resistance. Our findings provide insights into innate resistance to a small-molecule Met inhibitor and highlight rational combination therapies that could be evaluated in clinical trials. Time series experiment, four cell lines, 2 treatments
Project description:To understand epigenic dysregulation of host and viral genes upon EBV infection in human gastric cancer, genome wide transcripts by RNAseq were undertaken for total RNAs of 3 EBVnGC, their isogenic cell lines converted by in vitro EBV-infection and 3 EBV-naturally infected GC cell lines. Overall design: Three independent gastric cancer (GC) cell lines (NUGC3, SNU-484, SNU-638) were experimentally infected with AKATA strain of EBV to derive EBV-infected isogenic GC cell lines (NUGC3EBV, SNU-484EBV, SNU-638EBV). Three indepedent GC cell lines with natural EBV-infection (SNU-719, NCC24, YCCEL1)) were also included in this study.
Project description:Non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations have shown a dramatic response to EGFR inhibitors (EGFR-TKI). EGFR T790M mutation and MET amplification have been recognized as major mechanisms of acquired resistance to EGFR-TKI. Therefore, MET inhibitors have recently been used in NSCLC patients in clinical trials. In this study, we tried to identify the mechanism of acquired resistance to MET inhibitor. We analyzed the antitumor effects of two MET inhibitors, PHA-665752 and crizotinib, in 10 NSCLC cell lines. EBC1 cells with MET amplification were the only cells that were sensitive to both MET inhibitors. We established PHA-665752-resistant EBC1 cells, namely EBC1-R cells. EBC1-R cells showed overexpression of ATP-binding cassette sub-family B member 1 (ABCB1) as well as phosphorylation of MET. EBC1-R cells grew as cell spheres that exhibited cancer stem cell-like (CSC) properties and epithelial mesenchymal transition (EMT). The levels of two miRNAs, miR-374a and miR-138 which targeted ABCB1, were decreased in EBC1-R cells. ABCB1 siRNA and ABCB1 inhibitor elacridar could reduce sphere numbers and suppress EMT. Elacridar could also reverse the resistance to PHA-665752 in EBC1-R cells. Our study demonstrated that ABCB1 overexpression which was associated with CSC properties and EMT was involved in the acquired resistance to MET inhibitor. Inhibition of ABCB1 might be a novel therapeutic strategy for NSCLC patients with acquired resistance to MET inhibitor. Overall design: To search resistant mechanisms of met inhibitor in EBC1-R cell, we compared EBC-1 cell and EBC1-R cell.
Project description:Fucoidan is a high-molecular polysaccharide whose main constituent is sulfated fucose. Extensive studies have demonstrated numerous interesting biological activities for fucoidan. We specifically focused on the anti-proliferation activity of fucoidan and examined the underlying mechanism in MKN45 gastric cancer cells. BrdU assay revealed that fucoidan impeded the MKN45 cell cycle by approximately 50%, and clonogenic assay also showed that fucoidan inhibited cell proliferation. Preliminary examinations of fucoidan using LDH assay showed no immediate cytotoxic effects at 24-h exposure. However, longer time courses revealed inhibition of cell growth at 4 days in a dose-dependent manner. Microarray analysis in MKN45 cells treated with fucoidan identified genes that were upregulated and downregulated in response to fucoidan, including MAP3K5, or ASK1 (apoptosis signal-regulating kinase), which was upregulated by 1.38-fold. Western blot confirmed that fucoidan increased ASK1 protein levels, while reducing the levels of phosphorylated ASK1. Reduction of ASK1 by siRNA decreased proliferation of MKN45 cells. Our findings show that fucoidan may suppress cellular proliferation and DNA synthesis in MKN45 cells by suppressing the ASK1-p38 signaling pathway through reduction of phosphorylated ASK1 levels. Overall design: To identify potential genes involved in mediating the cellular effects of fucoidan, which is a high-molecular polysaccharide whose main constituent is sulfated fucose, total RNA was collected from cultured MKN45 gastric cancer cells and microarray expression analyses were performed using the Agilent Human microarray kit (Palo Alto, CA, US). A total of 20278 sequences were examined at DNA Chip Research Inc. (Kanagawa, Japan), and 496 genes were found to be upregulated and 774 genes were downregulated by fucoidan.
Project description:In order to define YAP1-specific gene expression patterns in gastric cancer, the constitutively active mutant YAP1 (YAP1-S127A) was over-expressed in MKN45 gastric cancer cells. Defined gene expression signature was later used to stratify gastric cancer patients according to the presence of the YAP1-activated signature. Three groups of samples are included: 1. Mock control; 2. Vector control; 3. YAP-S127A expression. Gene expression profiles of YAP-S127A mutant-expressing cells were compared to that of mock and vector control. Experiments were done in MKN45 gastric cancer cells.
Project description:Analysis to find splicing variants that are differentially expressed in a highly metastatic stomach cancer cell line, MKN45P, versus its parental cell line, MKN45 Overall design: Comparison between highly metastatic gastric cancer cell line MKN45P and its parental cell line MKN45
Project description:Analysis to find splicing variants that are differentially expressed in a highly metastatic stomach cancer cell line, MKN45P, versus its parental cell line, MKN45 Comparison between highly metastatic gastric cancer cell line MKN45P and its parental cell line MKN45
Project description:Expression of SET7/9, a histone methyltransferase, was frequently reduced in cultured and primary gastric cancers. To identify the SET7/9 target genes in gastric cancer, we performed siRNA-based knockdown of SET7/9 in MKN74 and MKN45 cells and then examined significant expression changes of genes by microarray. Transfection of SET7/9 siRNA into MKN74 and MKN45 cells were performed by electroporation. After 48hrs, cells were harvested. Total RNA was used for cDNA microarray.
Project description:Persistent colonization of the gastric mucosa by Helicobacter pylori (Hp) elicits chronic inflammation and aberrant epithelial cell proliferation, which increases the risk of gastric cancer. We examined the ability of microRNAs to modulate gastric cell proliferation in response to persistent Hp infection and found that epigenetic silencing of miR-210 plays a key role in gastric disease progression. Importantly, DNA methylation of the miR-210 gene was increased in Hp-positive human gastric biopsies as compared to Hp-negative controls. Moreover silencing of miR-210 in gastric epithelial cells promoted proliferation. We identified STMN1 and DIMT1 as miR-210 target genes and demonstrated that inhibition of miR-210 expression augmented cell proliferation by activating STMN1 and DIMT1. Together, our results highlight inflammation-induced epigenetic silencing of miR-210 as a mechanism of induction of chronic gastric diseases, including cancer, during Hp infection. To identify miR-210 targets in gastric cells, whole transcriptome analysis of AGS and MKN45 cells transfected with pre-miR-210 was conducted using Affymetrix GeneChip Human Genome U133 Plus 2.0 Array.
Project description:This study set out to identify global changes in gene expression in MKN45 gastric epithelial cells following 8 hours stimulation with 10 μg/ml lipopolysaccharide (LPS) from the gastric pathogen H. pylori. Microarray analysis was used to compare changes in gene expression between cells treated with 10 μg/ml H. pylori LPS and untreated cells at the same time point. Total RNA was harvested from MKN45 cells following treatment with LPS for 8h or untreated cells at the same time-point. 2 independent experiments were carried out. RNA was labeled and hybridized to GeneChips to analyse changes in gene expression.