Epidermal Growth Factor Receptor In Lung Cancer Cells Research Articles

Proteasomal deubiquitylase activity enhances cell surface recycling of the epidermal growth factor receptor in non-small cell lung cancer.

The epidermal growth factor receptor (EGFR) represents a top therapeutic target in the treatment of non-small cell lung cancer. EGFR expression is intricately modulated by receptor endocytosis, during which EGFR ubiquitylation and deubiquitylation play fundamental roles to govern receptor fate. This study aims to uncover novel aspects of the endocytic regulation of EGFR trafficking by deubiquitylases. The expression and ubiquitylation of EGFR in non-small cell lung cancer cells treated with deubiquitylase inhibitors were assessed by immunoblotting, immunoprecipitation and mass spectrometry analyses. The intracellular EGFR distribution was investigated using immunofluorescence and confocal microscopy assays, and colocalizations with endocytic compartments were examined using GFP-tagged Rab proteins as markers. The influence of the proteasomal deubiquitylase inhibitor b-AP15 on EGF- and HSP90 inhibitor-induced EGFR downregulation was evaluated by immunoblotting. The anticancer effects of b-AP15 were assessed by cell proliferation, colony formation and flow cytometry assays, as well as xenograft animal models. We found that b-AP15 caused a dramatically enhanced ubiquitylation of EGFR in lung cancer cells. Treatment with b-AP15 decreased cell surface EGFR levels and accumulated EGFR on recycling endosomes marked with Rab4A and Rab11A. b-AP15 effectively repressed EGF- and HSP90 inhibitor-induced EGFR degradation. Lung cancer cells exposed to b-AP15 showed markedly reduced cell propagation and significantly increased cell apoptosis. Furthermore, b-AP15 effectively inhibited tumor xenograft growth in nude mice. Proteasomal USP14 and UCHL5 act collectively to promote cell surface recovery of EGFR. Inhibition of proteasomal deubiquitylase activity induces increased EGFR ubiquitylation and retention on recycling endosomes. The USP14 and UCHL5 dual inhibitor b-AP15 elicits potent tumor-suppressive effects to deter cell proliferation and induce apoptotic cell death in lung cancer.

Ubiquilin proteins regulate EGFR levels and activity in lung adenocarcinoma cells.

Ubiquilin (UBQLN) proteins are involved in diverse cellular processes like endoplasmic reticulum-associated degradation, autophagy, apoptosis, and epithelial-to-mesenchymal transition. UBQLNs interact with a variety of substrates, including cell surface receptors, transcription factor regulators, proteasomal machinery proteins, and transmembrane proteins. In addition, previous work from our lab shows that UBQLN1 interacts with insulin-like growth factor receptor family members (IGF1R, IGF2R, and INSR) and this interaction regulates the activity and proteostasis of IGFR family members. We wondered whether UBQLN proteins could also bind and regulate additional receptor tyrosine kinases. Thus, we investigated a link between UBQLN and the oncogene epidermal growth factor receptor (EGFR) in lung adenocarcinoma cells. Loss of UBQLN1 occurs at high frequency in human lung cancer patient samples and we have shown that the loss of UBQLN1 is capable of altering processes involved in cell proliferation, migration, invasion, and epithelial-to-mesenchymal transition in lung adenocarcinoma cell lines. Here, we present data that loss of UBQLN1 resulted in increased turnover of total EGFR while increasing the relative amount of phosphorylated EGFR in lung adenocarcinoma cells, especially in the presence of its ligand EGF. Furthermore, the loss of UBQLN1 led to a more invasive cell phenotype as manifested by increased proliferation, migration, and speed of movement of these lung adenocarcinoma cells. Taken together, UBQLN1 regulates the expression and stability of EGFR in lung cancer cells.

Inhibition of COX-2 and EGFR by Melafolone Improves Anti-PD-1 Therapy through Vascular Normalization and PD-L1 Downregulation in Lung Cancer

Checkpoint blockade therapy has been proven efficacious in lung cancer patients. However, primary/acquired resistance hampers its efficacy. Therefore, there is an urgent need to develop novel strategies to improve checkpoint blockade therapy. Here we tested whether dual inhibition of cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) by flavonoid melafolone improves program death 1 (PD-1) checkpoint blockade therapy through normalizing tumor vasculature and PD-1 ligand (PD-L1) downregulation. Virtual screening assay, cellular thermal shift assay, and enzyme inhibition assay identified melafolone as a potential inhibitor of COX-2 and EGFR. In Lewis lung carcinoma (LLC) and CMT167 models, dual inhibition of COX-2 and EGFR by melafolone promoted survival, tumor growth inhibition, and vascular normalization, and ameliorated CD8+ T-cell suppression, accompanied by the downregulation of transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF), and PD-L1 in the tumor cells. Mechanistically, dual inhibition of COX-2 and EGFR in lung cancer cells by melafolone increased the migration of pericyte, decreased the proliferation and migration of endothelial cells, and enhanced the proliferation and effector function of CD8+ T cells through VEGF, TGF-β, or PD-L1 downregulation and PI3K/AKT inactivation. Notably, melafolone improved PD-1 immunotherapy against LLC and CMT167 tumors. Together, dual inhibition of COX-2 and EGFR by melafolone improves checkpoint blockade therapy through vascular normalization and PD-L1 downregulation and, by affecting vessels and immune cells, may be a promising combination strategy for the treatment of human lung cancer.

Mechanisms for DNA-damaging agent-induced inactivation of ErbB2 and ErbB3 via the ERK and p38 signaling pathways.

Cisplatin (CDDP) and doxorubicin (DOX) are chemotherapeutic drugs that trigger apoptosis by inducing DNA-damage. A previous study using breast cancer cells demonstrated the negative feedback modulation of the epidermal growth factor receptor (EGFR) and receptor tyrosine-protein kinase erbB-2 (ErbB2) via extracellular signal-regulated kinase (ERK)-mediated phosphorylation of conserved Thr-669 and Thr-677 residues, respectively, in the juxtamembrane domain. In addition, CDDP has been identified to cause negative feedback inhibition of activated EGFR in lung cancer cells. In the present study, the role of phosphorylation in the feedback control of the ErbB2/ErbB3 heterodimer in human breast and gastric cancer cells was investigated. Phosphorylation of ErbB2 at Thr-677 was induced by CDDP and DOX, which in turn reduced tyrosine autophosphorylation of ErbB2 and ErbB3. Treatment with trametinib, a mitogen-activated protein kinase inhibitor that blocks ERK-mediated Thr-677 phosphorylation, and substitution of Thr-677 to alanine, blocked the feedback inhibition of ErbB2 and ErbB3. In addition, these agents caused the degradation of ErbB proteins through the activation of p38 mitogen-activated protein kinase (p38) and ERK. These results demonstrate that chemotherapeutic agents trigger ERK- and p38-mediated post-translational downregulation of ErbB receptors.

Abstract 546: Impact of therapeutic EGFR inhibition on immune checkpoint blockade in head and neck squamous cell carcinoma

Abstract Patients with advanced recurrent and/or metastatic head and neck squamous cell carcinoma (HNSCC) have few effective treatment options and a poor median survival of 6-8 months. Limited improvement in overall survival has been observed in HNSCC patients treated with EGFR inhibitors despite high expression of epidermal growth factor receptor (EGFR) in these tumors. Remarkable clinical results are emerging from immunotherapy targeting programmed death-1 (PD1) and its ligand programmed death ligand-1 (PDL1). Blockade of the PD1/PDL1 interaction is believed to enhance endogenous anti-tumor immunity by restoring T cell cytotoxic action. PDL1 is highly expressed in primary, recurrent, and metastatic HNSCC and phase 1 clinical trials are ongoing for monoclonal antibodies targeting the PD1/PDL1 axis in HNSCC. We found that activation of EGFR in HNSCC cells by epidermal growth factor (EGF) significantly increases PDL1 expression in a dose dependent manner. EGFR inhibition using tyrosine kinase inhibitors (TKI) or cetuximab suppresses this EGF-induced PDL1 expression in cells with both wild type and constitutively active EGFR. This is consistent with published data that constitutively active EGFR in lung cancer cells correlates with higher PDL1 expression, and this can be reversed by EGFR inhibition. These results suggest there may be interactions between EGFR-targeted therapy and immunotherapy involving the PD1/PDL1 axis. To evaluate potential therapeutic interactions, we used an immunocompetent, syngeneic mouse model of human EGFR-expressing TUBO cancer cells on a BALB/c background. The murine TUBO-EGFR cells are sensitive to human EGFR inhibitors both in vitro and in vivo. Initial studies show that treatment of tumors with EGFR inhibitor (erlotinib) results in increased intratumoral CD8+ T cell infiltration and tumor regression, suggesting that EGFR inhibition can impact the anti-tumor T cell response. We are currently evaluating the effects of EGFR inhibition on PDL1 expression and tumor response to PD1/PDL1 blockade using this model. Further, a clinical trial investigating the impact of cetuximab treatment on intratumoral expression of PDL1 in HNSCC patients is planned to open shortly. We conclude that signaling mediated by EGFR can impact expression of PDL1 by HNSCC. Understanding the interactions between EGFR inhibitors and immune checkpoint blockade could lead to new approaches to combining TKI and cancer immunotherapy. Citation Format: Laura M. Rogers, Madelyn M. Espinosa-Cotton, Andrean L. Simons, George J. Weiner. Impact of therapeutic EGFR inhibition on immune checkpoint blockade in head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 546.

EGFR Transactivation by Peptide G Protein-Coupled Receptors in Cancer.

Lung cancer kills approximately 1.3 million citizens in the world annually. The tyrosine kinase inhibitors (TKI) erlotinib and gefitinib are effective anti-tumor agents especially in lung cancer patients with epidermal growth factor receptor (EGFR) mutations. The goal is to increase the potency of TKI in lung cancer patients with wild type EGFR. G protein-coupled receptors (GPCR) transactivate the wild type EGFR in lung cancer cells. The GPCR can be activated by peptide agonists causing phosphatidylinositol turnover or stimulation of adenylylcyclase. Recently, nonpeptide antagonists were found to inhibit the EGFR transactivation caused by peptides. Nonpeptide antagonists for bombesin (BB), neurotensin (NTS) and cholecystokinin (CCK) inhibit lung cancer growth and increase the cytotoxicity of gefitinib. The results suggest that GPCR transactivation of the EGFR may play an important role in cancer cell proliferation.

P0037 A novel method of surface-enhanced Raman scattering to detect mutant EGFR status of malignant pleural effusion

Background Somatic mutations in the epidermal growth factor receptor (EGFR) gene are common in patients with lung adenocarcinomas and are associated with sensitivity to the small molecule tyrosine kinase inhibitors (TKIs). For 10–50% of the patients who have malignant pleural effusion (MPE), pathological diagnosis might rely exclusively on finding lung cancer cells in the MPE. Current methods based on polymerase chain reaction were used to test mutant EGFR status of MPE samples, but the accuracy of the test data is very low, resulting in many patients losing the chance of TKI treatment. Methods We synthesised a novel bioprobe, which consisted of the seaurchin-like Au nanocluster (AuNC), crystal violet, polyethylene glycol, and mutant-specific EGFR antibody. The bioprobe was used to detect the status of mutant EGFR in samples from 35 patients with lung cancer. Findings The bioprobe had excellent surface-enhanced Raman scattering (SERS) activity and recognition capability towards mutant EGFR in lung cancer cells. The enhancement factor of bioprobe reached 1.97 × 107. Characteristic SERS signal at 1617 cm−1 of CV correlated linearly with number of H1650 cells, demonstrating the minimum detection limit of 25 cells in 1 ml suspension. The quantity of bioprobes engulfed by single H1650 cells in 2 h ranged from 56 to 62. Furthermore, SERS was pre-clinically used to test mutant EGFR status in MPE samples from 35 patients with lung adenocarcinoma. Principal component analysis and support vector machine algorithms were constructed for mutant EGFR diagnostic analysis, yielding an overall accuracy of 90.7%. Interpretation SERS measurement based on sea urchin-like AuNC was an efficient method for the detection of mutant EGFR in MPE and might have potential in applications such as predicting the genotype of clinical lung cancer in the near future.

Abnormal activation of the EGFR signaling pathway mediates the downregulation of miR-145 through the ERK1/2 in non-small cell lung cancer

The expression of miR-145 with tumor suppressor function is decreased in lung cancer cells. Epidermal growth factor receptor (EGFR) signaling pathway is abnormally activated in lung cancer cells. It is not clear whether the EGFR signaling pathway is involved in the regulation of miR-145 expression in lung cancer. In the present study, we found that the reduction of miR-145 was associated with EGFR abnormal activation in lung cancer cells. AG1478, an inhibitor of EGFR, may restore the expression of miR-145, indicating that EGFR activation is involved in the downregulation of miR-145 in lung cancer cells. Then, the application of STAT3, AKT and ERK1/2 inhibitors and siRNA against these signaling molecules indicated that ERK1/2 or AKT instead of STAT3 was involved in the process of miR-145 downregulation by EGFR. It was confirmed that AKT through activation of the ERK1/2 signaling molecules mediated the effect of EGFR on miR-145. Furthermore, we found that EGFR downregulated miR-145 through ERK1/2 in lung cancer cells. These findings establish EGFR and miR-145 links in lung cancer cells and therefore contribute to a better understanding of the role of EGFR in lung cancer cells, and provide clues for in-depth study of miR-145 expression and a possible direction for the further increase of miR-145 in lung cancer cells.

Akt kinase-interacting protein1, a novel therapeutic target for lung cancer with EGFR-activating and gatekeeper mutations

Despite initial dramatic response, epidermal growth factor receptor (EGFR) mutant lung cancer patients always acquire resistance to EGFR-tyrosine kinase inhibitors (TKIs). Gatekeeper T790M mutation in EGFR is the most prevalent genetic alteration underlying acquired resistance to EGFR-TKI, and EGFR mutant lung cancer cells are reported to be addictive to EGFR/Akt signaling even after acquired T790M mutation. Here, we focused on Akt kinase-interacting protein1 (Aki1), a scaffold protein of PI3K (phosphoinositide 3-kinase)/PDK1 (3-phosphoinositide-dependent protein kinase)/Akt that determines receptor signal selectivity for non-mutated EGFR, and assessed its role in EGFR mutant lung cancer with or without gatekeeper T790M mutation. Cell line-based assays showed that Aki1 constitutively associates with mutant EGFR in lung cancer cells with (H1975) or without (PC-9 and HCC827) T790M gatekeeper mutation. Silencing of Aki1 induced apoptosis of EGFR mutant lung cancer cells. Treatment with Aki1 siRNA dramatically inhibited growth of H1975 cells in a xenograft model. Moreover, silencing of Aki1 further potentiated growth inhibitory effect of new generation EGFR-TKIs against H1975 cells in vitro. Aki1 was frequently expressed in tumor cells of EGFR mutant lung cancer patients (53/56 cases), including those with acquired resistance to EGFR-TKI treatment (7/7 cases). Our data suggest that Aki1 may be a critical mediator of survival signaling from mutant EGFR to Akt, and may therefore be an ideal target for EGFR mutant lung cancer patients, especially those with acquired EGFR-TKI resistance due to EGFR T790M gatekeeper mutation.

Morphine Stimulates the Phosphorylation and Nuclear Translocation of EGFR in Lung Cancer Cells.

Mu opioid receptor (MOR) stimulates MAPK/ERK phosphorylation, by transactivating epidermal growth factor receptor (EGFR) in astrocytes (Belcheva MM et al J Biol Chem 2001, 276, 33847–53) and by transactivating vascular endothelial growth factor receptor-2 (VEGFR2) in endothelial cells (Chen C et al Curr Neurovasc Res 2006, 3, 171–80). EGFR and VEGFR2 are two critical targets for lung cancer therapy. Since opioids used to treat pain in cancer act via MOR, it is critical to understand the role of MOR in growth and survival promoting signaling in lung cancer. Therefore, we examined if MOR co-activates, EGFR mediated signaling in non-small cell human lung cancer cells, HL2009, HL1299 and HL460; and VEGFR2 in murine blood outgrowth endothelial cells (BOEC) derived from wild type (wt) and MOR knockout (KO) mice. We observed that HL2009 cells showed a 3–5 fold higher expression of MOR (by RT-PCR) as well as constitutive activation of phospho-EGFR (by Western) as compared to HL1299 and HL460. Morphine (100 nM) stimulated the phosphorylation of EGFR, MAPK/ERK and Akt in a time-dependent manner similar to that induced by 10 nM EGF, in HL2009 but not in HL460 cells. Morphine as well as EGF-induced phosphorylation peaked after 10 and 30 min of stimulation and it was accompanied by the translocation of phospho-EGFR to the nucleus in HL2009 but not in HL460 cells. Since, nuclear expression of phospho-EGFR is associated with poor prognosis in some human cancers, it is possible that MOR activation upon opioid exposure may impart resistance to lung cancer therapy, by stimulating the translocation of phospho-EGFR to the nucleus. On the other hand, morphine also stimulated the phosphorylation of VEGFR2 and MAPK/ERK in BOEC from wt mice but not in BOEC from MOR KO mice. Thus, opioid analgesics may stimulate VEGFR2 via MOR and stimulate angiogenesis. Acquired resistance to EGFR therapy in non small cell lung cancer is associated with increased VEGF activity. Therefore, simultaneous co-activation of EGFR and VEGFR2 via MOR in lung cancer may promote cancer progression and resistance to VEGF and/or EGFR based therapies. We speculate that MOR-specific antagonists in combination with VEGF/EGFR based therapies may prove to be beneficial in treating lung cancer.