• Archives of Pharmacal Research
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• v.28 no.11
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• pp.1275-1281
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• 2005

The $G_{q/11}$ protein-coupled receptors, such as muscarinic (M1 & M3) receptors, have been shown to regulate the release of a soluble amyloid precursor protein (sAPP$\alpha$) produced from $\alpha$-secretase processing. However, there is no direct evidence for the precise characteristics of G proteins, and the signaling mechanism for the regulation of $G_{q/11}$ protein-coupled receptor mediated sAPP$\alpha$ release is not clearly understood. This study examined whether the muscarinic receptor-mediated release of sAPP$\alpha$ is directly regulated by $G\alpha_{q/11}$ proteins. The HEK293 cells were transiently cotransfected with muscarinic M3 receptors and a dominant-negative minigene construct of the G protein $\alpha$ subunit. The sAPP$\alpha$ release in the media was measured using an antibody specific for sAPP. The sAPP$\alpha$ release enhancement induced by muscarinic receptor stimulation was decreased by a $G_{q/11}$ minigene construct, whereas it was not blocked by a control minigene construct (the G$\alpha$ carboxy peptide in random order, G$\alpha_{q}$R) or $G\alpha_{j}$ constructs. This indicated a direct role of the $G\alpha_{q/11}$ protein in the regulation of muscarinic M3 receptor-mediated sAPP$\alpha$ release. We also investigated whether the transactivation of the epidermal growth factor receptor (EGFR) by a muscarinic agonist could regulate the sAPP$\alpha$ release in SH-SY5Y cells. Pretreatment of a specific EGFR kinase inhibitor, tyrophostin AG1478 (250 nM), blocked the EGF-stimulated sAPP$\alpha$ release, but did not block the oxoM­stimulated sAPP$\alpha$ release. This demonstrated that the transactivation of the EGFR by muscarinic receptor activation was not involved in the muscarinic receptor-mediated sAPP$\alpha$ release.

• Molecules and Cells
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• v.20 no.2
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• pp.263-270
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• 2005

Transactivation of EGF-receptor (EGFR) by G-protein coupled receptors (GPCRs) is emerging as an important pathway in cell proliferation, which plays a crucial role in the development of atherosclerotic lesion. Angiotensin II (Ang II) has been identified to have a major role in the formation of atherosclerotic lesions, although the underlying mechanisms remain largely unclear. We hypothesize that Ang II promotes the proliferation and migration of smooth muscle cells through the release of heparin-binding epidermal growth factor like growth factor (HB-EGF), transactivation of EGFR and activation of Akt and Erk 1/2, with matrix metalloproteases (MMPs) playing a dispensable role. Primary rat aortic smooth muscle cells were used in this study. Smooth muscle cells rendered quiescent by serum deprivation for 12 h were treated with Ang II (100 nM) in the presence of either GM6001 ($20{\mu}M$), a specific inhibitor of MMPs or AG1478 ($10{\mu}M$), an inhibitor of EGFR. The levels of phosphorylation of EGFR, Akt and Erk 1/2 were assessed in the cell lysates. Inhibition of MMPs by GM6001 significantly attenuated Ang II-stimulated phosphorylation of EGFR, suggesting that MMPs may be involved in the transactivation of EGFR by Ang II receptor. Furthermore Ang II-stimulated proliferation and migration of smooth muscle cells were significantly blunted by inhibiting MMPs and EGFR and applying HB-EGF neutralization antibody, indicating that MMPs, HB-EGF and EGFR activation is necessary for Ang-II stimulated migration and proliferation of smooth muscle cells. Our results suggest that inhibition of MMPs may represent one of the strategies to counter the mitogenic and motogenic effects of Ang II on smooth muscle cells and thereby prevent the formation and development of atherosclerotic lesions.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.9
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• pp.4341-4346
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• 2012

Purpose: The aim of this study was to cast light on initiating molecular events associated with the development of premalignant oral lesions induced by tobacco and/or areca nut. Method: Immunohistochemical analyses of cell cycle regulatory proteins (LIMD1, RBSP3, p16, RB, phosphorylated RB, p53), EGFR and SH3GL2 (EGFR associated protein) were performed with inflammatory/ulcerative epithelium and adjacent hyperplastic/mild dysplastic lesions. Results: No change in expression of the proteins was seen in inflammatory epithelium. Reduced nuclear expression of LIMD1 was evident in ulcerative epithelium. In hyperplastic lesions, reduced expression of RBSP3, p16, SH3GL2 and overexpression of p-RB and EGFR were apparent. Reduced nuclear expression of p53 was observed in mild dysplastic lesions. Conclusion: Our data suggest that inactivation of LIMD1 in ulcerative epithelium might predispose the tissues to alterations of other cell cycle regulatory and EGFR signaling proteins needed for the development of premalignant oral lesions.

• Tuberculosis and Respiratory Diseases
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• v.75 no.6
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• pp.236-237
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• 2013

Many attempts have been made to find genetic abnormalities inducing carcinogenesis after the development of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor targeting EGFR in lung cancer. New target therapies have been already commercialized and studied along with the recent discovery of gene rearrangement involved in the carcinogenic process of non-small cell lung cancer. This study aims to investigate anplastic lymphoma kinase, c-ros oncogene 1, and receptor tyrosine kinase, in particular.

• Radiation Oncology Journal
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• v.25 no.4
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• pp.233-241
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• 2007

Purpose: We examined the effect of the dual EGFR/HER2 tyrosine kinase inhibitor, GW572016, on EGFR/HER2 receptor phosphorylation, inhibition of downstream signaling and radiosensitization in either an EGFR or HER2 overexpressing human breast cancer xenograft. Materials and Methods: We established SCID mice xenografts from 4 human breast cancer cell line that overexpressed EGFR or HER 2 (SUM 102, SUM 149, SUM 185, SUM 225). Two series of xenografts were established. One series was established for determining inhibition of the EGFR/HER2 receptor and downstream signaling activities by GW572016. The other series was established for determining the radiosensitization effect of GW572016. Inhibition of the receptor and downstream signaling proteins were measured by the use of immunoprecipitation and Western blotting. For determining the in vivo radiosensitization effect of GW572016, we compared tumor growth delay curves in the following four treatment arms: a) control; b) GW572016 alone; c) radiotherapy (RT) alone; d) GW572016 and RT. Results: GW572016 inhibited EGFR, HER2 receptor phosphorylation in SUM 149 and SUM 185 xenografts. In addition, the p44/42 MAPK (ERK 1/2) downstream signaling pathway was inactivated by GW572016 in the SUM 185 xenograft. In the SUM 225 xenograft, we could not observe inhibition of HER2 receptor phosphorylation by GW572016; both p44/42 MAPK (Erk1/2) and Akt downstream signal protein phosphorylation were inhibited by GW572016. GW572016 inhibited growth of the tumor xenograft of SUM 149 and SUM 185. The combination of GW572016 and RT enhanced growth inhibition greater than that with GW572016 alone or with RT alone in the SUM 149 xenograft. GW572016 appears to act as an in vivo radiosensitizer. Conclusion: GW572016 inhibited EGFR/HER2 receptor phosphorylation and downstream signaling pathway proteins. GW572016 modestly inhibited the growth of tumor in the SUM 185 xenograft and showed radiosensitization in the SUM 149 xenograft. Our results suggest that a better predictor of radiation response would be inhibition of a crucial signaling pathway than inhibition of a receptor.

• Journal of Life Science
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• v.28 no.2
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• pp.265-273
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• 2018

Estrogen (E2) is involved in the development and progression of breast cancer and is mediated by estrogen receptor (ER). ER plays important roles in cellular proliferation, migration, invasion and causing drug resistance through diverse cross-talks with epidermal growth factor receptor (EGFR) and insulin-like growth factor-1 receptor (IGF-1R) signaling pathways in breast cancer cells. Breast cancer is caused mainly by break-down of homeostasis of endocrine signaling pathways especially by the uncontrolled expression and increased activities of E2/IGF-1/EGF, ER/G-protein estrogen receptor (GPER)/IGF-1R/EGFR and their intracellular signaling mediators. These changes influence the complex cross-talk between E2 and growth factors' signaling, eventually resulting in the progression of cancer and resistance against endocrine regulators. Thus, elucidation of the molecular mechanisms in stepwise of the cross-talk between E2 and growth factors will contribute to the customized treatment according to the diverse types of breast cancer. In particular, as strategies for the treatment of breast cancer with diverse genotypes and phenotypes, there can be use of aromatase inhibitors and blockers of E2 action for the ER+ hormone-dependent breast cancer cells and use of IGF-1R/EGFR activity blockers for suppression of cancer cell proliferation from the cross-talk between E2 and growth factors. Furthermore, changes in the expression of the ECM molecules regulated by the cross-talk between ER and EGFR/IGF-1R can be used for the targeted therapeutics against the migration of breast cancer cells. Therefore, it is required for the cross-talk among the signaling pathways of ER, GPER, IGF-1R and EGFR concerning cancer progression to be elucidated in more detail at the molecular level.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.9
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• pp.3927-3932
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• 2014

Background: Epidermal growth factor receptor (EGFR) mutations and echinoderm microtubule associated protein like 4-anaplastic lymphoma kinase (EML4-ALK) define specific molecular subsets of lung adenocarcinomas with distinct clinical features. Our purpose was to analyze clinical features and prognostic value of EGFR gene mutations and the EML4-ALK fusion gene in lung adenocarcinoma. Patients and Methods: EGFR gene mutations and the EML4-ALK fusion gene were detected in 92 lung adenocarcinoma patients in China. Tumor marker levels before first treatment were measured by electrochemiluminescence immunoassay. Results: EGFR mutations were found in 40.2% (37/92) of lung adenocarcinoma patients, being identified at high frequencies in never-smokers (48.3% vs. 26.5% in smokers; P=0.040) and in patients with abnormal serum carcinoembryonic antigen (CEA) levels before the initial treatment (58.3% vs. 28.6%, P=0.004). Multivariate analysis revealed that a higher serum CEA level before the initial treatment was independently associated with EGFR gene mutations (95%CI: 1.476~11.343, P=0.007). We also identified 8 patients who harbored the EML4-ALK fusion gene (8.7%, 8/92). In concordance with previous reports, younger age was a clinical feature for these (P=0.008). Seven of the positive cases were never smokers, and no coexistence with EGFR mutation was discovered. In addition, the frequency of the EML4-ALK fusion gene among patients with a serum CEA concentration below 5ng/ml seemed to be higher than patients with a concentration over 5ng/ml (P=0.021). No significant difference was observed for time to progression and overall survival between EML4-ALK-positive group and EML4-ALK-negative group or between patients with and without an EGFR mutation. Conclusions: The serum CEA level before the initial treatment may be helpful in screening population for EGFR mutations or EML4-ALK fusion gene presence in lung adenocarcinoma patients.

• Tuberculosis and Respiratory Diseases
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• v.68 no.1
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• pp.22-28
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• 2010

Background: Vascular endothelial growth factor (VEGF) is a potent mediator of angiogenesis. VEGF production is regulated by HIF-$1{\alpha}$ and EGFR. This study examined the relationship between the clinicopathological factors and VEGF, HIF-$1{\alpha}$ and EGFR protein overexpression, and evaluated their prognostic value in patients with a surgically resected non-small cell lung cancer (NSCLC). Methods: Patients who underwent a surgical resection at Kangnam St. Mary's hospital were reviewed retrospectively. The core biopsy samples from 54 patients with NSCLC were assembled on a tissue microarray (TMA), and immunohistochemical staining for the VEGF, HIF-$1{\alpha}$ and EGFR proteins was performed. The overexpression of these proteins was evaluated in relation to age, gender, histology and staging by univariate analysis. The clinicopathological prognostic factors were analyzed. Results: Multivariate analysis performed by Cox regression (odds ratio 2.8, 95% CI 1.0~8.2, p=0.046) revealed HIF-$1{\alpha}$ overexpression to be an unfavorable factor. There was no correlation between the overexpression of these proteins and the clinicopathological factors. VEGF showed a positive relationship with EGFR, but there was no statistical significance [$p(x^2)=0.06$]. Conclusion: HIF-$1{\alpha}$ overexpression predicts shorter survival in patients with a surgically resected NSCLC. Therefore, HIF-$1{\alpha}$ may be a poor prognostic factor in NSCLC.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.24
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• pp.10875-10878
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• 2015

The epidermal growth factor receptor (EGFR) is an important surface receptor with N-glycans in its extracellular domain, whose glycosylation is essential for its function, especially in tumor cells. Here, we demonstrated that polylactosamine is markedly increased in H7721 hepatocellular carcinoma cells after treatment with EGF, while it apparently declined after exposure to all-trans retinoic acid (ATRA). In the study of the enzymatic mechanism of this phenomenon, we explored changes in the expression of poly-N-acetyllactosamine (PLN) branching glycosyltransferases using RT-PCR. Among the four glycosyltransferases with altered expression, GnT-V was most elevated by EGF, while GnT-V and B3GNT2 were most declined by ATRA. Next, we conducted co-immunoprecipitation experiments to test whether B3GNT2 and EGFR associate with each other. We observed that EGFR is a B3GNT2-targeting protein in H7721 cells. Taken together, these findings indicated that the altered expression of B3GNT2 will remodel the PLN stucture of EGFR in H7721 cells, which may modify downstream signal transduction.

• Journal of Microbiology and Biotechnology
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• v.27 no.1
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• pp.49-56
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• 2017

In the human airway, mucus exists to protect the respiratory system as a primary barrier of the innate immune system. However, hyperexpressed mucus limits airflow, resulting in a decrease of lung function. Among more than 20 mucin family members, MUC5AC and MUC5B are major glycoproteins in human airway mucus. The epidermal growth factor receptor (EGFR) signaling pathway is one of the mechanisms of these mucins expression and specificity protein-1 (Sp1) transcription factor is the downstream signal of this pathway, playing pivotal roles in mucin expression. Even though there are some drugs for treating mucus hypersecretion, no drug has proven effects on humans. We found that the flavonoid tilianin regulated MUC5AC expression and also inhibited Sp1 phosphorylation. In this study, we investigated how tilianin would modulate EGFR signaling and regulate mucin production. In conclusion, tilianin inhibited MUC5AC expression mediated via modulating the EGFR-MEK-ERK-Sp1 signaling pathway in NCI-H292 human airway epithelial cells. This study may provide the basis for the novel treatment of mucus hypersecretion.