scholarly journals Ligand-Independent EGFR Activation by Anchorage-Stimulated Src Promotes Cancer Cell Proliferation and Cetuximab Resistance via ErbB3 Phosphorylation

Cancers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1552 ◽  
Author(s):  
Masami Nozaki ◽  
Hiroki Yasui ◽  
Yuichi Ohnishi
Keyword(s):  
Cell Growth ◽  
Cell Lines ◽  
Kinase Inhibitors ◽  
Specific Binding ◽  
Locally Advanced ◽  
Growth Factor Receptor ◽  
Resistant Cell ◽  
Egfr Inhibitor ◽  
Egfr Activation ◽  
Egfr Tyrosine Kinase Inhibitors

Activation of the epidermal growth factor receptor (EGFR) pathway plays an important role in the progression of cancer and is associated with a poor prognosis in patients. The monoclonal antibody cetuximab, which displays EGFR extracellular domain-specific binding, has proven effective in the treatment of locally advanced disease and relapsed/metastatic disease. However, the effects of cetuximab are weaker than those of EGFR tyrosine kinase inhibitors (TKIs). This study investigates differences in the effects on cell growth of cetuximab and EGFR TKI AG1478 at the molecular level using oral squamous cell carcinoma (OSCC) cell lines. First, we found that there were EGFR-inhibitor-sensitive (EIS) and EGFR-inhibitor-resistant cell lines. The EIS cell lines expressed not only EGFR but also ErbB3, and both were clearly phosphorylated. The levels of phosphorylated ErbB3 were unaffected by cetuximab but were reduced by AG1478. EGFR ligand treatment increased the levels of phosphorylated EGFR but not phosphorylated ErbB3. Moreover, when EIS cell lines that were only capable of anchorage-dependent growth were grown in suspension, cell growth was suppressed and the levels of phosphorylated focal adhesion kinase (FAK), Src, and ErbB3 were significantly reduced. The levels of phosphorylated ErbB3 were unaffected by the FAK inhibitor PF573228, but were reduced by Src inhibition. Finally, combining cetuximab and a Src inhibitor produced an additive effect on the inhibition of EIS cell line growth.

scholarly journals Ligand-Independent EGFR Activation by Anchorage Stimulated Src Promotes Cancer Cell Proliferation and Cetuximab Resistance via ErbB3 Phosphorylation

2019 ◽  
Author(s):  
Masami Nozaki ◽  
Hiroki Yasui ◽  
Yuichi Ohnishi
Keyword(s):  
Cell Growth ◽  
Cell Lines ◽  
Kinase Inhibitors ◽  
Specific Binding ◽  
Locally Advanced ◽  
Resistant Cell ◽  
Egfr Inhibitor ◽  
Egfr Activation ◽  
Egfr Tyrosine Kinase Inhibitors ◽  
Dependent Growth

Activation of the EGFR pathway plays an important role in the progression of cancer and is associated with a poor prognosis in patients. The monoclonal antibody cetuximab, which displays EGFR extracellular domain-specific binding, has proven effective in the treatment of locally advanced disease and relapsed/metastatic disease. However, the effects of cetuximab are weaker than those of EGFR tyrosine kinase inhibitors (TKIs). This study investigates differences in the effects on cell growth of cetuximab and EGFR TKI AG1478 at the molecular level using oral squamous cell carcinoma (OSCC) cell lines. First, we found that there were EGFR-inhibitor sensitive (EIS) and EGFR-inhibitor resistant cell lines. The EIS cell lines expressed not only EGFR but also ErbB3, and both were clearly phosphorylated. The levels of phosphorylated ErbB3 were unaffected by cetuximab but were reduced by AG1478. EGFR ligand treatment increased the levels of phosphorylated EGFR but not phosphorylated ErbB3. Moreover, when EIS cell lines that were only capable of anchorage-dependent growth were grown in suspension, cell growth was suppressed and the levels of phosphorylated FAK, Src, and ErbB3 were significantly reduced. The levels of phosphorylated ErbB3 were unaffected by the FAK inhibitor PF573228, but were reduced by Src inhibition. Finally, combining cetuximab and a Src inhibitor produced an additive effect on the inhibition of EIS cell line growth.

scholarly journals Discovery of a novel EGFR ligand DPBA that degrades EGFR and suppresses EGFR-positive NSCLC growth

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Nan Yao ◽  
Chen-Ran Wang ◽  
Ming-Qun Liu ◽  
Ying-Jie Li ◽  
Wei-Min Chen ◽  
...  
Keyword(s):  
Kinase Inhibitors ◽  
Growth Factor Receptor ◽  
Recycling Endosome ◽  
Egfr Activation ◽  
Survival Pathways ◽  
Egfr Ligand ◽  
Egfr Tyrosine Kinase Inhibitors ◽  
Egfr Tkis

Abstract Epidermal growth factor receptor (EGFR) activation plays a pivotal role in EGFR-driven non-small cell lung cancer (NSCLC) and is considered as a key target of molecular targeted therapy. EGFR tyrosine kinase inhibitors (TKIs) have been canonically used in NSCLC treatment. However, prevalent innate and acquired resistances and EGFR kinase-independent pro-survival properties limit the clinical efficacy of EGFR TKIs. Therefore, the discovery of novel EGFR degraders is a promising approach towards improving therapeutic efficacy and overcoming drug resistance. Here, we identified a 23-hydroxybetulinic acid derivative, namely DPBA, as a novel EGFR small-molecule ligand. It exerted potent in vitro and in vivo anticancer activity in both EGFR wild type and mutant NSCLC by degrading EGFR. Mechanistic studies disclosed that DPBA binds to the EGFR extracellular domain at sites differing from those of EGF and EGFR. DPBA did not induce EGFR dimerization, phosphorylation, and ubiquitination, but it significantly promoted EGFR degradation and repressed downstream survival pathways. Further analyses showed that DPBA induced clathrin-independent EGFR endocytosis mediated by flotillin-dependent lipid rafts and unaffected by EGFR TKIs. Activation of the early and late endosome markers rab5 and rab7 but not the recycling endosome marker rab11 was involved in DPBA-induced EGFR lysosomal degradation. The present study offers a new EGFR ligand for EGFR pharmacological degradation and proposes it as a potential treatment for EGFR-positive NSCLC, particularly NSCLC with innate or acquired EGFR TKI resistance. DPBA can also serve as a chemical probe in the studies on EGFR trafficking and degradation.

scholarly journals DRES-13. DUAL KINASE INHIBITION TO COMBAT EGFR-INHIBITOR RESISTANCE IN GLIOBLASTOMA

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi74-vi74
Author(s):  
Erin Smithberger ◽  
Abigail Shelton ◽  
Madison Butler ◽  
Alex Flores ◽  
Ryan Bash ◽  
...  
Keyword(s):  
Kinase Inhibitors ◽  
Alternative Pathway ◽  
Growth Factor Receptor ◽  
Cell Types ◽  
Genetically Engineered ◽  
Differentially Expressed ◽  
Egfr Inhibitor ◽  
Tumor Resistance ◽  
Pten Deletion ◽  
In Cells

Abstract Glioblastoma (GBM) is an aggressive primary brain tumor with a poor survival rate. One of the most common molecular alterations seen in GBM is amplification and/or mutation of the Epidermal Growth Factor Receptor (EGFR), which has made it an attractive therapeutic target. However, several EGFR tyrosine kinase inhibitors have been tested clinically in GBM with minimal success. One reason for this lack of efficacy could be due to acute, adaptive resistance via alternative pathway activation. To investigate this mechanism of tumor resistance, we used RNA-seq and multiplex inhibitor bead/mass spectrometry (MIB-MS) to analyze the transcriptomes and kinomes of genetically engineered murine astrocytes with common GBM genotypes. We have previously shown that 38% of the expressed kinome varied among a panel of diverse nGEM astrocytes harboring Cdkn2a deletion (C) plus Pten deletion (CP), wild-type human EGFR (CE) or EGFRvIII (CEv3) overexpression or both EGFRvIII overexpression and Pten deletion (CEv3P). Although CE have a similar transcriptional profile to C cells at baseline, when treated with the EGFR inhibitor afatinib, CE respond more similarly to CEv3 cells. When cells containing endogenous murine EGFR (C and CP) are treated with afatinib, fewer than 0.5% of kinases showed differential expression. In cells with EGFR overexpression alone, more than 6% of kinases were differentially expressed upon afatinib treatment, including Ntrk3, Fgfr2 and 3, Lyn, Bmx, Epha2 and 5, Fn3k, a kinase involved in fructosamine processing, and Nrbp2, a kinase involved in regulation of apoptosis. This effect was blunted in cells lacking Pten in addition to having EGFRvIII (CEv3P), resulting in less than 2% of kinases being differentially expressed. The only kinase upregulated in all three EGFR-overexpressing cell types was Coq8a, which is involved in electron transport and response to DNA damage. Given this overlap in response, Coq8a could be a potential dual treatment target for GBM.

scholarly journals A Case Report of Primary Resistance to EGFR TKI in Lung Adenocarcinoma Due to Coexisting MET Exon 14 Skipping Mutation with Excellent Response to Combination of Gefitinib and Capmatinib

2021 ◽  
Author(s):  
Nirmal Vivek Raut ◽  
Siddharth Srivastava ◽  
Guarav Dilip Gangwani ◽  
Heena Sajid Ali
Keyword(s):  
Kinase Inhibitors ◽  
Single Gene ◽  
Growth Factor Receptor ◽  
Nonsmall Cell Lung Cancer ◽  
Primary Resistance ◽  
Gene Testing ◽  
Comprehensive Genomic Profiling ◽  
Egfr Tyrosine Kinase Inhibitors ◽  
Next Generation Sequencing Ngs ◽  
Egfr Tki

AbstractTreatment of nonsmall cell lung cancer (NSCLC) carrying an epidermal growth factor receptor (EGFR) mutation depends on EGFR tyrosine kinase inhibitors (TKIs). However, all patients treated with EGFR TKI eventually develop progressive disease. Approximately, 20% of patients do not respond to EGFR TKIs, which is defined as primary resistance. The prognosis of these patients is similar to NSCLC with nondriver mutations. We report a case of a patient with EGFR exon 21 mutation who rapidly progressed in 15 days on Gefitinib. Next-generation sequencing (NGS) showed a MET exon 14 skip mutation coexisting with EGFR exon 21 mutation, causing primary resistance to EGFR TKI. Based on NGS reports, a treatment combining Gefitinib and Capmatinib, a MET inhibitor, induced a rapid response in the patient, which was sustained at the end of 8 months. This clearly emphasizes the need for comprehensive genomic profiling using NGS over single gene testing.

scholarly journals Efficacy of the CDK4/6 Dual Inhibitor Abemaciclib in EGFR-Mutated NSCLC Cell Lines with Different Resistance Mechanisms to Osimertinib

Cancers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 6
Author(s):  
Silvia La Monica ◽  
Claudia Fumarola ◽  
Daniele Cretella ◽  
Mara Bonelli ◽  
Roberta Minari ◽  
...  
Keyword(s):  
Cell Lines ◽  
Kinase Inhibitor ◽  
Acquired Resistance ◽  
Growth Factor Receptor ◽  
Resistance Mechanisms ◽  
Resistant Cell ◽  
Nsclc Cell ◽  
Dual Inhibitor ◽  
Nsclc Patients ◽  
Egfr Mutated

Abemaciclib is an inhibitor of cyclin-dependent kinases (CDK) 4 and 6 that inhibits the transition from the G1 to the S phase of the cell cycle by blocking downstream CDK4/6-mediated phosphorylation of Rb. The effects of abemaciclib alone or combined with the third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) osimertinib were examined in a panel of PC9 and HCC827 osimertinib-resistant non-small cell lung cancer (NSCLC) cell lines carrying EGFR-dependent or -independent mechanisms of intrinsic or acquired resistance. Differently from sensitive cells, all the resistant cell lines analyzed maintained p-Rb, which may be considered as a biomarker of osimertinib resistance and a potential target for therapeutic intervention. In these models, abemaciclib inhibited cell growth, spheroid formation, colony formation, and induced senescence, and its efficacy was not enhanced in the presence of osimertinib. Interestingly, in osimertinib sensitive PC9, PC9T790M, and H1975 cells the combination of abemaciclib with osimertinib significantly inhibited the onset of resistance in long-term experiments. Our findings provide a preclinical support for using abemaciclib to treat resistance in EGFR mutated NSCLC patients progressed to osimertinib either as single treatment or combined with osimertinib, and suggest the combination of osimertinib with abemaciclib as a potential approach to prevent or delay osimertinib resistance in first-line treatment.

scholarly journals ERβ1 Expression Patterns Have Different Effects On EGFR TKIs Treatment Response in EGFR Mutant Lung Adenocarcinomas.

2020 ◽  
Author(s):  
Lijuan Zhang ◽  
Meng Tian ◽  
Jiamao Lin ◽  
Jianbo Zhang ◽  
Haiyong Wang ◽  
...  
Keyword(s):  
Western Blot ◽  
Cell Lines ◽  
Kinase Inhibitors ◽  
Expression Patterns ◽  
Estrogen Therapy ◽  
Growth Factor Receptor ◽  
Treatment Resistance ◽  
Progression Free Survival ◽  
Pathway Activation ◽  
Egfr Tkis

Abstract Background: Estrogen receptor β (ERβ) can regulate cellular signaling through non-genomic mechanisms, potentially promoting resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). However, the mechanisms underlying the ERβ-mediated resistance to EGFR TKIs remain poorly understood. Methods: qRT-PCR was performed to investigate ERβ1 and ERβ5 expression levels in cell lines. The localization of ERβ and ERβ1 within cells was assessed using immunocytochemistry and immunofluorescence. The effect of estradiol and/or gefitinib on EGFR signaling pathways was determined by western blot. Cell viability and colony formation assays were used to assess gefitinib response for different cell lines. The apoptosis was verified by tunel and western blot. Immunohistochemistry was used to assess the expression of ERβ1 in lung adenocarcinoma tissues. Patient survival was estimated using the Kaplan-Meier method, and comparisons between groups were conducted using log-rank tests. Results: PC9 cell lines stably overexpressing ERβ1 or ERβ1/ERβ5 were established successfully. Immunofluorescence revealed that ERβ5 overexpression partly retained ERβ1 in the cytoplasm. Immunoblotting analyses revealed that EGFR pathway activation levels were higher in PC9/ERβ1/5 cells than those in PC9/ERβ1 or control PC9 cells. In the presence of estradiol, PI3K/AKT/mTOR pathway activation levels were higher in ERβ1/5-expressing cells than those in ERβ1-expressing cells. Additionally, PC9/ERβ1/5 cells were less prone to the cytotoxic and pro-apoptotic effects of gefitinib compared with PC9/ERβ1 or control PC9 cells. Conclusion: Cytoplasmic ERβ1 was associated with poor progression-free survival in lung cancer patients treated with EGFR TKIs. These results suggest that anti-estrogen therapy might reverse EGFR TKI treatment resistance to some extent in selected patients.

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