Mutations in EGFR compromise hypoxia associated radiation resistance through impaired repair of replication fork associated DNA double-strand breaks
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE95564 | GEO | 2017/03/02
SECONDARY ACCESSION(S): PRJNA377535
REPOSITORIES: GEO
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Project description:EGFR signaling has been implicated in hypoxia-associated resistance to radiation or chemotherapy. Non-small cell lung carcinomas (NSCLC) with activating L858R or ?E746-E750 EGFR mutations exhibit elevated EGFR activity and downstream signaling. Here, relative to wild-type (WT) EGFR, mutant (MT) EGFR expression significantly increases radiosensitivity in hypoxic cells. Gene expression profiling in human bronchial epithelial cells (HBEC) revealed that MT-EGFR expression elevated transcripts related to cell cycle and replication in aerobic and hypoxic conditions and downregulated RAD50, a critical component of nonhomologous end joining and homologous recombination DNA repair pathways. NSCLCs and HBEC with MT-EGFR revealed elevated basal and hypoxia-induced ?-H2AX-associated DNA lesions that were coincident with replication protein A in the S-phase nuclei. DNA fiber analysis showed that, relative to WT-EGFR, MT-EGFR NSCLCs harbored significantly higher levels of stalled replication forks and decreased fork velocities in aerobic and hypoxic conditions. EGFR blockade by cetuximab significantly increased radiosensitivity in hypoxic cells, recapitulating MT-EGFR expression and closely resembling synthetic lethality of PARP inhibition.Implications: This study demonstrates that within an altered DNA damage response of hypoxic NSCLC cells, mutant EGFR expression, or EGFR blockade by cetuximab exerts a synthetic lethality effect and significantly compromises radiation resistance in hypoxic tumor cells. Mol Cancer Res; 15(11); 1503-16. ©2017 AACR.
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Project description:We previously reported that differential protein degradation of TKI-sensitive [L858R, del(E746-A750)] and resistant (T790M) epidermal growth factor receptor (EGFR) mutants upon erlotinib treatment correlates with drug sensitivity. However, the molecular mechanism remains unclear. We also reported SMAD ubiquitination regulatory factor 2 (SMURF2) as a stabilizer of EGFR in a ligase (E3) activity-dependent manner. Here, using in vitro and in vivo ubiquitination assays, mass spectrometry, and super-resolution microscopy, we show SMURF2-EGFR functional interaction is critical in receptor stability and TKI sensitivity. We found that L858R/T790M EGFR is a preferred substrate of SMURF2-UBCH5 (an E3-E2) complex-mediated K63-linked polyubiquitination, which preferentially stabilizes mutant receptor. We identified three lysine (K) residues (K721, 1037 and 1164) as the sites of ubiquitination and replacement of K to acetylation-mimicking asparagine (Q) at K1037 position in L858R/T790M background converts the stable protein sensitive to erlotinib-induced degradation. Using STochastic Optical Reconstruction Microscopy (STORM) imaging, we show that SMURF2 presence allows longer membrane retention of activated EGFR upon EGF treatment, whereas, siRNA-mediated SMURF2 knockdown fastens receptor endocytosis and lysosome enrichment. In an erlotinib-sensitive PC9 cells, SMURF2 overexpression increased EGFR levels with improved erlotinib tolerance, whereas, SMURF2 knockdown decreased EGFR steady state levels in NCI-H1975 and PC9-AR cells to overcome erlotinib and AZD-9291 resistance respectively. Additionally, disruption of the SMURF2-UBCH5 complex destabilized EGFR. Together, we propose that SMURF2-mediated preferential polyubiquitination of L858R/T790M EGFR may be competing with acetylation-mediated receptor internalization to provide enhanced receptor stability and that disruption of the E3-E2 complex may be an attractive alternate to overcome TKI resistance
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Project description:Mutations in the epidermal growth factor receptor (EGFR) kinase domain occur in 10-30% of lung adenocarcinoma. Leucine to arginine substitution at amino acid position 858 (L858R) accounts for around 50% of EGFR-tyrosine kinase inhibitor (TKI) sensitizing mutations. A second site mutation in the gatekeeper residue (T790M) accounts for around 60% of acquired resistance to EGFR-TKIs. We sought to identify the immediate direct and indirect targets of these mutant EGFRs in lung adenocarcinoma and their modulation by erlotinib, the first generation, and most widely used EGFR-directed TKI. We undertook stable isotope labeling of amino acids in cell culture (SILAC), phosphopeptide enrichment, and quantitative mass spectrometry to identify dynamic changes of phosphorylation downstream of mutant EGFRs in lung adenocarcinoma cells harboring L858R or L858R/T790M mutations and their modulation by erlotinib inhibition. Phosphorylation at the majority of phosphosites identified exhibited no change upon either EGF stimulation or erlotinib inhibition. Only around 7% of phosphosites identified and quantified showed increased phosphorylation upon EGF stimulation in either cell line. However, while phosphorylation at 61% of these phosphosites decreased upon erlotinib inhibition in the TKI sensitive H3255 cells, only 24% of such sites exhibited decreased phosphorylation upon erlotinib inhibition in the TKI resistant H1975 cells. Top canonical pathways that were inhibited upon erlotinib treatment in sensitive cells, but not the resistant cells include EGFR, Insulin receptor, HGF, MAPK, mTOR, p70S6K and JAK/STAT signaling. We identified phosphosites in proteins of the autophagy network, such as ULK1 (S623) that is constitutive phosphorylated in these lung adenocarcinoma cells, but phosphorylation is inhibited upon erlotinib treatment in sensitive cells, but not resistant cells. Finally, kinase-substrate prediction analysis from our data indicated that substrates of basophilic kinase families, AGC, CAMK and STE were significantly enriched and those of proline directed kinase families, CMGC and CK were significantly depleted among substrates that exhibit increased phosphorylation upon EGF stimulation and reduced phosphorylation upon TKI inhibition. This is the first study to date to examine global phosphorylation changes upon erlotinib treatment of lung adenocarcinoma cells and results from this study provide new insights into signaling downstream of mutant EGFRs in lung adenocarcinoma.
2015-01-30 | PXD001101 | Pride
Project description:Controlled activation of epidermal growth factor receptor (EGFR) is systematically guaranteed at the molecular level, however aberrant activation of EGFR is frequently found in cancer. Transcription induced by EGFR activation often involves coordinated expression of genes that positively and negatively regulate the original signaling pathway, therefore alterations in EGFR kinase activity may reflect changes in gene expression associated with the pathway. In this study, we investigated transcriptional changes following EGF stimulation with or without the EGFR kinase inhibitor Iressa in H1299 human non-small-cell lung cancer cells (parental H1299, H1299 cells which overexpress wild-type: EGFR-WT and mutant EGFR: L858R). Our results clearly showed differences in transcriptional activity in the absence or presence of EGFR kinase activity, and genes sharing the same molecular functions showed distinct expression dynamics. The results showed particular enrichment of EGFR/ErbB signaling-related genes in a differentially expressed gene set, and significant protein expression of MIG6/RALT(ERRFI1), an EGFR negative regulator, was confirmed in L858R. High MIG6 protein expression was correlated with basal EGFR phosphorylation and inversely correlated with EGF-induced ERK phosphorylation levels. Investigation of NCI-60 cell lines showed that ERRFI1 expression was correlated with EGFR expression regardless of tissue type. These results suggest that cells accumulate MIG6 as an inherent negative regulator to suppress excess EGFR activity when basal EGFR kinase activity is considerably high. Taken together, an EGFR mutation can cause transcriptional changes to accommodate the activation potency of the original signaling pathway at the cellular level. Experiment Overall Design: H1299 human non-small cell lung cancer cells were stimulated by the growth hormone (epidermal growth factor (EGF)) or EGFR kinase inhibitor (Iressa). Control was set as non-treated cells.
2009-08-09 | E-GEOD-11729 | biostudies-arrayexpress
Project description:To identify gene expression changes associated with receptor tyrosine kinase (RTK) activation, we performed RNA-Seq analysis of murine pro-B BAF3 cells over-expressing the oncogenic form of EGFR (EGFR-L858R-T790M), FGFR (TEL-FGFR1 fusion), MET (TPR-MET fusion) or RET (CCDC6-RET fusion) genes. We reported the RTK-driven transcriptional reprogramming of metabolic genes.
2020-04-10 | GSE111292 | GEO
Project description:Controlled activation of epidermal growth factor receptor (EGFR) is systematically guaranteed at the molecular level, however aberrant activation of EGFR is frequently found in cancer. Transcription induced by EGFR activation often involves coordinated expression of genes that positively and negatively regulate the original signaling pathway, therefore alterations in EGFR kinase activity may reflect changes in gene expression associated with the pathway. In this study, we investigated transcriptional changes following EGF stimulation with or without the EGFR kinase inhibitor Iressa in H1299 human non-small-cell lung cancer cells (parental H1299, H1299 cells which overexpress wild-type: EGFR-WT and mutant EGFR: L858R). Our results clearly showed differences in transcriptional activity in the absence or presence of EGFR kinase activity, and genes sharing the same molecular functions showed distinct expression dynamics. The results showed particular enrichment of EGFR/ErbB signaling-related genes in a differentially expressed gene set, and significant protein expression of MIG6/RALT(ERRFI1), an EGFR negative regulator, was confirmed in L858R. High MIG6 protein expression was correlated with basal EGFR phosphorylation and inversely correlated with EGF-induced ERK phosphorylation levels. Investigation of NCI-60 cell lines showed that ERRFI1 expression was correlated with EGFR expression regardless of tissue type. These results suggest that cells accumulate MIG6 as an inherent negative regulator to suppress excess EGFR activity when basal EGFR kinase activity is considerably high. Taken together, an EGFR mutation can cause transcriptional changes to accommodate the activation potency of the original signaling pathway at the cellular level.
2009-07-30 | GSE11729 | GEO
Project description:Lung cancer is the leading cause of cancer death. Mutations in the kinase domain of EGFR, a predominant driver oncogene, such as L858R missense mutation and a series of deletions spanning the conserved sequence 747LREA750, are associated with sensitivity to tyrosine kinase inhibitors (TKIs). However, patients receiving EGFR-TKIs (gefitinib and erlotinib) develop drug-resistance due to a secondary mutation at the gatekeeper residue (T790M) in about 50-60% of cases, urging for new drug development. Afatinib, a FDA approved second-generation EGFR-TKI that was developed to circumvent T790M-mediated resistance, has not been very effective in clinical trials. In this study, we performed a global phosphoproteomic screen to identify targets that undergo mutant EGFR-dependent tyrosine phosphorylation and their modulation by erlotinib or afatinib. We undertook stable isotope labeling of amino acids in cell culture (SILAC), phosphopeptide enrichment, and quantitative mass spectrometry to identify dynamic changes of phosphorylation downstream of mutant EGFRs in lung adenocarcinoma cells harboring L858R or L858R/T790M mutations and their modulation by erlotinib and afatinib inhibition. We identified and quantified 397, 429, 223, and 594 phosphotyrosine sites in H3255, 11-18,PC9, and H1975 cell lines that were grown in presence of FBS and in presence/absence of TKIs, respectively. These account for a total of 907 unique phospho-tyrosine sites in 496 proteins. Among them, 187 phosphotyrosine sites were found to be in 89 kinases, which may serve as intermediary regulatory kinases in EGFR signalling pathway. Further analysis indicated that in TKI-sensitive H3255 and 11-18 cells, there were 58/111 and 65/101 tyrosine sites that were hypophosphorylated in presence of erlotinib and afatinib, respectively. However, in TKI-resistant H1975 cells, 189 and 264 tyrosine sites were hypophosphorylated in presence of erlotinib and afatinib respectively, indicating that the afatinib-specific additional sites could be validated for identifying potentially new drug targets to counter TKI-resistance. Ingenuity pathway analysis (IPA) of proteins with altered phosphorylation sites demonstrated that several canonical pathways including ephrin receptor signalling and integrin signalling pathways were enriched, which may play important roles in cell growth and proliferation. However, upon EGF stimulation of serum starved H3255 cells in presence or absence of TKIs, 99 tyrosine sites that were hyperphosphorylated upon EGF stimulation were inhibited in presence of erlotinib or afatinib. But in H1975 cells treated with erlotinib, 48 of the above sites were either unchanged or were hyperphosphorylated. These sites include EGFR (Y1197/869/998), JAK1 (Y1034), FRK (Y497), GAB1 (Y657/689), MAPK1 (Y187), MAPK3 (Y204), MET (Y1252/1253). Furthermore, a total of 112 sites that were observed to be hypophosphorylated upon EGF stimulation in H1975 cells, were found to be hyperphosphorylated upon erlotinib inhibition. This could possibly be due to the activation of downstream phosphatases with EGF stimulation. We are now performing in-depth bioinformatic analysis and validation experiments using functional genomics to understand the role of targets of mutant EGFR signalling in lung cancer.
2017-03-29 | PXD004373 | Pride