• 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.

• BMB Reports
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• v.53 no.3
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• pp.133-141
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• 2020

The epidermal growth factor receptor (EGFR), a member of the ErbB family (EGFR, ErbB2, ErbB3 and ErbB4), plays a crucial role in regulating various cellular responses such as proliferation, differentiation, and survival. As a result, aberrant activation of EGFR, mostly mediated through different classes of genomic alterations occurring within EGFR, is closely associated with the pathogenesis of numerous human cancers including lung adenocarcinoma, glioblastoma, and colorectal cancer. Thus, specific suppression of oncogenic activity of mutant EGFR with its targeted drugs has been routinely used in the clinic as a very effective anti-cancer strategy in treating a subset of tumors driven by such oncogenic EGFR mutants. However, the clinical efficacy of EGFR-targeted therapy does not last long due to several resistance mechanisms that emerge in the patients following the drug treatment. Thus, there is an urgent need for the development of novel therapeutic tactics specifically targeting mutant EGFR with the focus on the unique biological features of various mutant EGFR. Regarding this point, our review specifically emphasizes the recent findings about distinct requirements of receptor dimerization and autophosphorylation, which are critical steps for enzymatic activation of EGFR and signaling cascades, respectively, among wildtype and mutant EGFR and further discuss their clinical significance. In addition, the molecular mechanisms regulating EGFR dimerization and enzymatic activity by a key negative feedback inhibitor Mig6 as well as the clinical use for developing potential novel drugs targeting it are described in this review.

• BMB Reports
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• v.34 no.1
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• pp.66-72
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• 2001

To investigate the mechanism of adriamycin (ADM) resistance in the ADM resistant subline PC-14/ADM, we examined the expressions of p-glycoprotein (P-gp), topoisomerase I (Topo I) and II (Topo II), glutathione-S-transferases (GSTs), tissue transglutaminase (t-TG), epidermal growth factor receptor (EGFR), and E-cadherin and the activity of superoxide dismutase (SOD) in PC-14 and PC-14/ADM cells. There was no change in the cellular levels of P-gp, Topo I, Topo II, and the two isoforms of GSTs. However, SOD activity in PC-14/ADM cells was 2.38 fold higher than that in PC-14 cells. A marked induction of the t-TG expression was also observed in PC-14/ADM cells. In addition to those changes, expressions of EGFR and E-cadherin were down regulated in PC-14/ADM cells. Therefore, molecular modifications such as an increase in SOD activity, induction of the t-TG expression, and down regulation of EGFR and E-cadherin expressions may play important roles in PC-14/ADM cells during the development of ADM resistance.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.11
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• pp.4493-4497
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• 2014

Background: Epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) can predict the clinical response to tyrosine kinase inhibitor (TKI) therapy. However, EGFR mutations may be different in primary tumors (PT) and metastatic lymph nodes (MLN). The aim of this study was to compare EGFR mutations between PT and the corresponding MLN in NSCLC patients, and provide some guidelines for clinical treatment using TKI therapy. Materials and Methods: A systematic review and meta-analysis was performed with several research databases. Relative risk (RR) with the 95% confidence interval (CI) were used to investigate the EGFR mutation status between PT and the corresponding MLN. A random-effects model was used. Results: 9 publications involving 707 patients were included in the analysis. It was found that activation of EGFR mutations identified in PT and the corresponding MLN was 26.4% (187/707) and 19.9% (141/707), respectively. The overall discordance rate in our meta-analysis was 12.2% (86/707). The relative risk (RR) for EGFR mutation in PT relative to MLN was 1.33 (95%CI: 1.10-1.60; random-effects model). There was no significant heterogeneity between the studies ($I^2$=5%, p=0.003). Conclusions: There exists a considerable degree of EGFR mutation discrepancy in NSCLC between PT and corresponding MLN, suggesting that tumor heterogeneity might arise at the molecular level during the process of metastasis.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.24
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• pp.10627-10630
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• 2015

Background: Epidermal growth factor receptor (EGFR) mutations play a vital role in the prognosis of patients with lung adenocarcinoma. Such somatic mutations are more common in women who are non-smokers with adenocarcinoma and are of Asian origin. However, to our knowledge, there are few studies that have focused on men. Materials and Methods: One hundred and eighty-four consecutive patients (90 men and 94 women) of resected lung adenocarcinoma were studied retrospectively. Results: EGFR mutations were positive in 48.9% and negative (wild type) in 51.1%. Overall mutation was significant in women (66.0% vs. 32.2%) compared with men (p<0.001). For overall patients, EGFR mutation status was associated with gender, pStage, pT status, lepidic dominant histologic subtype, pure or mixed ground-glass nodule type on computed tomography and smoking status. However, in men, EGFR mutation status was only associated with lepidic dominant histologic subtype and not the other variables. Interestingly, the Brinkman index of men with mutant EGFR also did not differ from that for the wild type ($680.0{\pm}619.3$ vs. $813.1{\pm}552.1$ p=0.1077). Conclusions: The clinical characteristics of men with lung adenocarcinoma related to EGFR mutation are not always similar to that of overall patients. Especially we failed to find the relationship between EGFR mutations and smoking status in men.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.126-130
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• 2016

Epidermal growth factor receptor(EGFR)는 HER family에 속하는 tyrosine kinase receptor로서 다양한 하류경로로 신호를 전달하여 세포 증식, 혈관 형성, 세포 사멸을 억제하는 역할을 한다. EGFR이 폐암의 형성에 중요한 역할을 하고 많은 상피세포 종양에서 비정상적으로 활성화됨에 따라 암 치료에 중요한 역할을 하고 있어 EGFR tyrosine kinase inhibitor(TKI)에 관한 많은 연구가 이루어졌다. 위와 같은 약 개발에 있어서 현재 가상 시뮬레이션을 통한 약 후보물질 개발이 진행되고 있다. 특히, Molecular docking 시뮬레이션은 기존의 실험적인 기술(X-ray crystallography, NMR)로는 연구하기가 어려웠던 protein과 ligand간의 상호작용을 예측하여 이에 대한 정보를 제공할 수 있다. 하지만, 우선적으로 Molecular docking 시뮬레이션은 정확한 validation을 기반으로 진행되어야 신뢰할 수 있는 정보를 얻을 수 있다. 따라서 이번 연구에서는 EDISON에서 제공하는 Dock 프로그램과 일반적으로 잘 알려진 Glide, Autodock 프로그램으로 protein data bank(PDB)에서 제공하는 EGFR wild type cocrystal을 redocking하는 방식을 통하여 최상위 rank pose의 RMSD 값을 통한 validation 성능을 비교함으로써 어떤 프로그램이 EGFR과 ligand 간의 결합예측을 하는데 있어서 보다 더 정확한 결과를 낼 수 있는지 알아보고자 하였고 시뮬레이션 결과 Autodock에서 가장 우수한 결과 값을 보여주었다.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.4
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• pp.2413-2419
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• 2013

Background: Use of epidermal growth factor receptor inhibitors (EGFR-TKIs ) is now standard for non-small-cell lung cancer (NSCLC). However, the effects of EGFR-TKIs in maintenance therapy for advanced NSCLC patients are still unclear. The preent meta-analysis was performed to examine pooled data of randomized control trials (RCT) where EGFR-TKIs were compared against placebo in maintenance regimens for patients with advanced NCSLC to quantify potential benefits and determine safety. Methods: Several data bases were searched, including PubMed, EMBASE and CENTRAL, and we performed an internet search of conference literature. The endpoints were objective response rates (ORR), progression-free survival (PFS) and overall survival (OS). We performed a meta-analysis of the published data, using Comprehensive Meta Analysis software (Version 2.0). with a fixed effects model and an additional random effects model, when applicable. The results of the meta-analysis are expressed as hazard ratios (HRs) or risk ratios (RRs), with their corresponding 95% confidence intervals (95%CIs). Results: The final analysis included six trials, covering 3,758 patients. Compared with placebo, EGFR-TKIs maintenance therapy improved ORR and PFS for patients with advanced NSCLC, the difference being statistically significant (P<0.05), but proved unable to prolong patients' OS. The main adverse reactions were diarrhea and rashes. Conclusion: EGFR-TKIs demonstrated encouraging efficacy, safety and survival when delivered as maintenance therapy for patients with advanced NSCLC after first-line chemotherapy, especially for the patients who had adenocarcinomas, were female, non-smokers and patients with EGFR gene mutations.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.2
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• pp.785-789
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• 2016

A key drug for treatment of EGFR mutation-positive non-small cell lung cancer is epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI). While the dosage of many general anti-tumor drugs is adjusted according to the patient body surface area, one uniform dose of most TKIs is recommended regardless of body size. In many cases, dose reduction or drug cessation is necessary due to adverse effects. Disease control, however, is frequently still effective, even after dose reduction. In this study, we retrospectively reviewed the characteristics of 26 patients at Fukuoka University Hospital between January 2004 and January 2015 in whom the EGFR-TKI dose was reduced with respect to progression free survival and overall survival. There were 10 and 16 patients in the gefitinib group and the erlotinib group, respectively. The median progression-free survival in the gefitinib group and the erlotinib group was 22.4 months and 14.1 months, respectively, and the median overall survival was 30.5 months and 32.4 months, respectively. After stratification of patients by body surface area, the overall median progression-free survival was significantly more prolonged in the low body surface area (<1.45 m2) group (25.6 months) compared to the high body surface area (>1.45 m2) group (9.7 months) (p=0.0131). These results indicate that low-dose EGFR-TKI may sufficiently control disease without side effects in lung cancer patients with a small body size.

• Tuberculosis and Respiratory Diseases
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• v.70 no.1
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• pp.21-27
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• 2011

Background: Although the gold standard method for research trials on epidermal growth factor receptor (EGFR) mutations has been direct sequencing, this approach has the limitations of low sensitivity and of being time-consuming. Peptide nucleic acid (PNA)-mediated polymerase chain reaction (PCR) clamping is known to be a more sensitive detection tool. The aim of this study was to compare the detection rate of $EGFR$ mutation and EGFR-tyrosine kinase inhibitor (TKI) responsiveness according to $EGFR$ mutation status using both methodologies. Methods: Clinical specimens from 112 NSCLC patients were analyzed for $EGFR$ mutations in exons 18, 19, 20, and 21. All clinical data and tumor specimens were obtained from 3 university hospitals in Korea. After genomic DNA was extracted from paraffin-embedded tissue specimens, both PNA-mediated PCR clamping and direct-sequencing were performed. The results and clinical response to $EGFR$-TKIs were compared. Results: Sequencing revealed a total of 35 (22.9%) mutations: 8 missense mutations in exon 21 and 26 deletion mutations in exon 19. PNA-mediated PCR clamping showed the presence of genomic alterations in 45 (28.3%) samples, including the 32 identified by sequencing plus 13 additional samples (6 in exon 19 and 7 in exon 21). Conclusion: PNA-mediated PCR clamping is simple and rapid, as well as a more sensitive method for screening of genomic alterations in $EGFR$ gene compared to direct sequencing. This data suggests that PNA-mediated PCR clamping should be implemented as a useful screening tool for detection of $EGFR$ mutations in clinical setting.

• Development and Reproduction
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• v.21 no.2
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• pp.131-138
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• 2017

This study was conducted to investigate stimulatory effect of epidermal growth factor (EGF) on nuclear maturation and the expression level of EGF-receptor (EGFR), GM-130 (a marker of Golgi apparatus), transport protein Sec61 subunit beta ($Sec61{\beta}$), and coatomer protein complex subunit gamma 2 (COPG2) in porcine oocytes. The cumulus-oocyte complexes were collected from follicle with 3-6 mm in diameter. They were incubated in medium with/without EGF for 22 h (IVM I) and subsequently incubated hormone-free medium with/without EGF for 22 h (IVM II). Nuclear maturation state was checked by aceto-orcein stain. Protein expression of EGFR, GM-130, $Sec61{\beta}$, and COPG2 were measured by immunofluorescence. In results, nuclear maturation of oocytes in EGF non-treated oocytes were significantly lower than EGF-treated groups at IVM I or IVM II stage (P<0.05), whereas maturational rate in EGF treatment groups at both of IVM stage was higher in among the all treatment groups (P<0.05). EGFR, GM-130, $Sec61{\beta}$ and COPG2 were expressed in the cytoplasm of oocytes. Especially, GM-130 and EGFR were strongly expressed, but $Sec61{\beta}$ and COPG2 were weakly expressed in cortical area of cytoplasm. The protein level of GM-130, $Sec61{\beta}$, and COPG2 were significantly higher in the EGF-treated groups (P<0.05). However EGFR was no difference between non EGF-treated groups and control. In conclusion, EGF plays an important role in the systems for oocyte maturation with endoplasmic reticulum and Golgi apparatus. In addition, the protein levels of $Sec61{\beta}$ and COPG2 could be changed by EGF in the porcine oocytes during maturation.