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Oligosaccharyltransferase Inhibition Overcomes Therapeutic Resistance to EGFR Tyrosine Kinase Inhibitors.

ABSTRACT: Asparagine (N)-linked glycosylation is a posttranslational modification essential for the function of complex transmembrane proteins. However, targeting glycosylation for cancer therapy has not been feasible due to generalized effects on all glycoproteins. Here, we perform sensitivity screening of 94 lung cancer cell lines using NGI-1, a small-molecule inhibitor of the oligosaccharyltransferase (OST) that partially disrupts N-linked glycosylation, and demonstrate a selective loss of tumor cell viability. This screen revealed NGI-1 sensitivity in just 11 of 94 (12%) cell lines, with a significant correlation between OST and EGFR inhibitors. In EGFR-mutant non-small cell lung cancer with EGFR tyrosine kinase inhibitor (TKI) resistance (PC9-GR, HCC827-GR, and H1975-OR), OST inhibition maintained its ability to induce cell-cycle arrest and a proliferative block. Addition of NGI-1 to EGFR TKI treatment was synthetic lethal in cells resistant to gefitinib, erlotinib, or osimertinib. OST inhibition invariably disrupted EGFR N-linked glycosylation and reduced activation of receptors either with or without the T790M TKI resistance mutation. OST inhibition also dissociated EGFR signaling from other coexpressed receptors like MET via altered receptor compartmentalization. Translation of this approach to preclinical models was accomplished through synthesis and delivery of NGI-1 nanoparticles, confirmation of in vivo activity through molecular imaging, and demonstration of significant tumor growth delay in TKI-resistant HCC827 and H1975 xenografts. This therapeutic strategy breaks from kinase-targeted approaches and validates N-linked glycosylation as an effective target in tumors driven by glycoprotein signaling.Significance:EGFR-mutant NSCLC is incurable despite the marked sensitivity of these tumors to EGFR TKIs. These findings identify N-linked glycosylation, a posttranslational modification common to EGFR and other oncogenic signaling proteins, as an effective therapeutic target that enhances tumor responses for EGFR-mutant NSCLC. Cancer Res; 78(17); 5094-106. ©2018 AACR.

SUBMITTER: Lopez Sambrooks C

PROVIDER: S-EPMC6125176 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature

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Oligosaccharyltransferase Inhibition Overcomes Therapeutic Resistance to EGFR Tyrosine Kinase Inhibitors.

Lopez Sambrooks Cecilia C Baro Marta M Quijano Amanda A Narayan Azeet A Cui Wei W Greninger Patricia P Egan Regina R Patel Abhijit A Benes Cyril H CH Saltzman W Mark WM Contessa Joseph N JN

Cancer research 20180719 17

Asparagine (N)-linked glycosylation is a posttranslational modification essential for the function of complex transmembrane proteins. However, targeting glycosylation for cancer therapy has not been feasible due to generalized effects on all glycoproteins. Here, we perform sensitivity screening of 94 lung cancer cell lines using NGI-1, a small-molecule inhibitor of the oligosaccharyltransferase (OST) that partially disrupts N-linked glycosylation, and demonstrate a selective loss of tumor cell v ...[more]

PMID: 30026325

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Project description:BackgroundEpidermal growth factor receptor (EGFR) inhibitors, including cetuximab and panitumumab, are valuable therapeutics for colorectal cancer (CRC), but resistance to these inhibitors is common. The reason for such resistance is not well understood, which hampers development of better therapeutic strategies. Although activating mutations in KRAS, BRAF and PIK3CA are considered major drivers of CRC resistance to EGFR inhibitors, therapeutic targeting of these drug resistance drivers has not produced substantial clinical benefit.MethodsWe exploited cell lines and mouse tumor models (cell line xenografts and patient derived xenografts) for experiments of genetic and pharmacologic depletion of EGFR and/or its family member HER2, including EGFR mutants, inhibition of EGFR ligand shedding, and biochemical analysis of signaling proteins, to delineate the mechanism of CRC resistance to EGFR inhibitors and to assess the therapeutic activity of PEPDG278D, which is a recombinant human protein that induces the degradation of both EGFR and HER2.ResultsThe sensitivity of CRC cells to cetuximab and panitumumab correlates with the ability of these drugs to induce EGFR downregulation. PEPDG278D strongly inhibits oncogenic signaling and growth of CRC cells by causing profound depletion of EGFR and HER2, regardless of activating mutations of KRAS, BRAF and PIK3CA. siRNA knockdown of EGFR or HER2 also inhibits CRC cells resistant to EGFR inhibitors. Tumors harboring mutated KRAS, BRAF and/or PIK3CA also overexpress EGFR ligands, further suggesting that EGFR signaling remains important to the tumors. While excessive tumor-generated high-affinity EGFR ligands block target engagement by PEPDG278D, aderbasib, an inhibitor of ADAM10 and ADAM17, enables PEPDG278D to exert strong antitumor activity by inhibiting ligand shedding. Moreover, adding fluorouracil, which is commonly used in CRC treatment, to the combination of PEPDG278D and aderbasib further enhances tumor inhibition.ConclusionsOur study shows that CRC resistance to EGFR inhibitors results primarily from the inability of the inhibitors to downregulate their target and that a PEPDG278D-based combination treatment overcomes the resistance.

Project description:Cetuximab, the FDA-approved anti-EGFR antibody for head and neck squamous cell carcinoma (HNSCC), has displayed limited efficacy due to the emergence of intrinsic and acquired resistance. We and others have demonstrated that cetuximab resistance in HNSCC is driven by alternative receptor tyrosine kinases (RTK), including HER3, MET, and AXL. In an effort to overcome cetuximab resistance and circumvent toxicities associated with the administration of multiple RTK inhibitors, we sought to identify a common molecular target that regulates expression of multiple RTK. Bromodomain-containing protein-4 (BRD4) has been shown to regulate the transcription of various RTK in the context of resistance to PI3K and HER2 inhibition in breast cancer models. We hypothesized that, in HNSCC, targeting BRD4 could overcome cetuximab resistance by depleting alternative RTK expression. We generated independent models of cetuximab resistance in HNSCC cell lines and interrogated their RTK and BRD4 expression profiles. Cetuximab-resistant clones displayed increased expression and activation of several RTK, such as MET and AXL, as well as an increased percentage of BRD4-expressing cells. Both genetic and pharmacologic inhibition of BRD4 abrogated cell viability in models of acquired and intrinsic cetuximab resistance and was associated with a robust decrease in alternative RTK expression by cetuximab. Combined treatment with cetuximab and bromodomain inhibitor JQ1 significantly delayed acquired resistance and RTK upregulation in patient-derived xenograft models of HNSCC. These findings indicate that the combination of cetuximab and bromodomain inhibition may be a promising therapeutic strategy for patients with HNSCC.Significance: Inhibition of bromodomain protein BRD4 represents a potential therapeutic strategy to circumvent the toxicities and financial burden of targeting the multiple receptor tyrosine kinases that drive cetuximab resistance in HNSCC and NSCLC.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/15/4331/F1.large.jpg Cancer Res; 78(15); 4331-43. ©2018 AACR.

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Oligosaccharyltransferase Inhibition Overcomes Therapeutic Resistance to EGFR Tyrosine Kinase Inhibitors.

Publications

Oligosaccharyltransferase Inhibition Overcomes Therapeutic Resistance to EGFR Tyrosine Kinase Inhibitors.

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