Unknown,Transcriptomics,Genomics,Proteomics

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The N-glycosylated isoform of M-NM-2-integrin as a potential biomarker and target in HER-2+ BC refractory to HER-2 targeted therapies.

ABSTRACT: Acquired resistance to trastuzumab, a rationally designed HER-2 targeting antibody, remains a major hurdle in management of HER-2 positive breast cancer (HER-2+ BC) patients. Potential resistance mechanisms are numerous, derived primarily from studies where HER-2 positive cell lines are chronically exposed to trastuzumab. Recent evidence suggests a role for epithelial-mesenchymal transition (EMT) in trastuzumab resistance, but a definitive link between the two has been difficult to establish because relevant model systems are lacking. When sub-populations of trastuzumab sensitive SKBR-3 cells were isolated using cloning rings, an (EMT) occurred spontaneously in several (3/8) clones. SKBR-3 EMT-clones featured increased spindle morphology, expressed N-glycosylated M-NM-21-integrin, and decreased HER-2, all characteristics shared by JIMT-1, a cell lines with intrinsic resistance to trastuzumab. SKBR-3 EMT-clones were characterized by gene expression profiling and mammosphere formation. The N-glycosylated isoform of M-NM-2-itnegrin was targeted with M-NM-2-integrin inhibiting antibody, AIIB2. Transcriptional profiling revealed that SKBR-3 EMT-clones underwent a shift from a luminal molecular subtype to a more aggressive mesenchymal/ basal phenotype. Isolating clones from SKBR-3 cells with enforced expression of a M-NM-2-integrin isoform lacking extensive N-glycosylation failed to increase the likelihood for spontaneous EMT in SKBR-3. However, specific inhibition of the heavily N-glycosylated variant of M-NM-21-integrin expressed by SKBR-3 EMT-clones restored epithelial morphology and impaired mammosphere formation. Furthermore, when SKBR-3 EMT-clones were treated with relevant doses of trastuzumab and lapatinib, they showed M-bM-^@M-^\spontaneousM-bM-^@M-^] resistance. In this study we describe a model of spontaneous EMT following clonal selection in HER-2+ cell line, SKBR-3. Using this model we establish the first direct link between EMT and resistance to HER-2 targeted therapies. We also identify the N-glycosylated isoform of M-NM-2-integrin as a potential biomarker and target in HER-2+ BC refractory to HER-2 targeted therapies. RNA was isolated from 10 breast cancer cell lines in triplicate. Pairwise gene expression differences were compared between each of the SKBR-3 cell lines (SKBR-3/ b1, SK-EV-C4, and SK-B1-C1). Features selected had at least a 2X difference in at least one comparison, with a one-way ANOVA corrected p-value of >0.05. In addition, expression profiles from SKBR-3/ EV and SK-B1-C1 cell were compared and a differential gene list was generated to include genes that differed by at least 1.5X, with a t-test p-value of >0.02 (unpaired, Bonferroni corrected). A total of 1940 entities met these criteria and the expression of these genes was investigated in all breast cancer cell lines.

ORGANISM(S): Homo sapiens

SUBMITTER: Kathryn Graham

PROVIDER: E-GEOD-40152 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Acquired resistance to trastuzumab, a rationally designed HER-2 targeting antibody, remains a major hurdle in management of HER-2 positive breast cancer (HER-2+ BC) patients. Potential resistance mechanisms are numerous, derived primarily from studies where HER-2 positive cell lines are chronically exposed to trastuzumab. Recent evidence suggests a role for epithelial-mesenchymal transition (EMT) in trastuzumab resistance, but a definitive link between the two has been difficult to establish because relevant model systems are lacking. When sub-populations of trastuzumab sensitive SKBR-3 cells were isolated using cloning rings, an (EMT) occurred spontaneously in several (3/8) clones. SKBR-3 EMT-clones featured increased spindle morphology, expressed N-glycosylated β1-integrin, and decreased HER-2, all characteristics shared by JIMT-1, a cell lines with intrinsic resistance to trastuzumab. SKBR-3 EMT-clones were characterized by gene expression profiling and mammosphere formation. The N-glycosylated isoform of β-itnegrin was targeted with β-integrin inhibiting antibody, AIIB2. Transcriptional profiling revealed that SKBR-3 EMT-clones underwent a shift from a luminal molecular subtype to a more aggressive mesenchymal/ basal phenotype. Isolating clones from SKBR-3 cells with enforced expression of a β-integrin isoform lacking extensive N-glycosylation failed to increase the likelihood for spontaneous EMT in SKBR-3. However, specific inhibition of the heavily N-glycosylated variant of β1-integrin expressed by SKBR-3 EMT-clones restored epithelial morphology and impaired mammosphere formation. Furthermore, when SKBR-3 EMT-clones were treated with relevant doses of trastuzumab and lapatinib, they showed “spontaneous” resistance. In this study we describe a model of spontaneous EMT following clonal selection in HER-2+ cell line, SKBR-3. Using this model we establish the first direct link between EMT and resistance to HER-2 targeted therapies. We also identify the N-glycosylated isoform of β-integrin as a potential biomarker and target in HER-2+ BC refractory to HER-2 targeted therapies.

Project description:Epithelial-mesenchymal transition (EMT) has recently been recognized as a key element of cell invasion, migration, metastasis, and drug resistance in several types of cancer, including non-small cell lung cancer (NSCLC). Our aim was to clarify microRNA (miRNA) -related mechanisms underlying EMT followed by acquired resistance to epidermal growth factor receptor tyrosine-kinase inhibitor (EGFR-TKI) in NSCLC. MiRNA expression profiles were examined before and after transforming growth factor-beta1 (TGF-M-NM-21) exposure in four human adenocarcinoma cell lines with or without EMT. Correlation between expressions of EMT-related miRNAs and resistance to EGFR-TKI gefitinib was evaluated. MiRNA array and quantitative RT-PCR revealed that TGF-M-NM-21 significantly induced overexpression of miR-134, miR-487b, and miR-655, which belong to the same cluster located on chromosome 14q32, in lung adenocarcinoma cells with EMT. MAGI2 (membrane-associated guanylate kinase, WW and PDZ domain-containing protein 2), a predicted target of these miRNAs and a scaffold protein required for PTEN (phosphatase and tensin homolog), was diminished in A549 cells with EMT after the TGF-M-NM-21 stimulation. Overexpression of miR-134 and miR-487b promoted the EMT phenomenon and affected the drug resistance to gefitinib, whereas knockdown of these miRNAs inhibited the EMT process and reversed TGF-M-NM-21-induced resistance to gefitinib. Our study demonstrated that the miR-134/487b/655 cluster contributed to the TGF-M-NM-21-induced EMT phenomenon and affected the resistance to gefitinib by directly targeting MAGI2, whose suppression subsequently caused loss of PTEN stability in lung cancer cells. The miR-134/miR-487b/miR-655 cluster may be new therapeutic targets in advanced lung adenocarcinoma patients, depending on the EMT phenomenon. miRNA expression profiles before and after TGF-M-NM-21 exposure were assessed in the four lung adenocarcinoma cell lines, A549, LC2/ad, PC3, and, PC9 by TaqMan miRNA arrays. Relative ratios of miRNAs in cells after TGF-M-NM-21 exposure were calculated when compared with the cells before TGF-M-NM-21 exposure.

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The N-glycosylated isoform of M-NM-2-integrin as a potential biomarker and target in HER-2+ BC refractory to HER-2 targeted therapies.

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