• Tuberculosis and Respiratory Diseases
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• v.71 no.4
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• pp.259-265
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• 2011

Background: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors, gefitinib and erlotinib, are effective therapies for non-small cell lung cancer (NSCLC) patients whose tumors harbor somatic mutations in EGFR. The mutations are, however, only found in about 30% of Asian NSCLC patients and all patients ultimately develop resistance to these agents. Ionizing radiation has been shown to induce autophosphorylation of EGFR and activate its downstream signaling pathways. In the present study, we have tested whether the effect of gefitinib treatment can be enhanced after ionizing radiation. Methods: We compared the PC-9 and A549 cell line with its radiation-resistant derivatives after gefitinib treatment with cell proliferation and apoptosis assay. We also analyzed the effect of gefitinib after ionizing radiation in PC-9, A549, and NCI-H460 cells. Cell proliferation was determined by MTT assay and induction of apoptosis was evaluated by flow cytometry. Caspase 3 activation and PARP cleavage were evaluated by western blot analysis. Results: PC-9 cells having mutated EGFR and their radiation-resistant cells showed no significant difference in cell viability. However, radiation-resistant A549 cells were more sensitive to gefitinib than were their parental cells. This was attributable to an increased induction of apoptosis. Gefitinib-induced apoptosis increased significantly after radiation in cells with wild type EGFR including A549 and NCI-H460, but not in PC-9 cells with mutated EGFR. Caspase 3 activation and PARP cleavage accompanied these findings. Conclusion: The data suggest that gefitinib-induced apoptosis could increase after radiation in cells with wild type EGFR, but not in cells with mutated EGFR.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.5
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• pp.396-402
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• 2011

Introduction: Epidermal growth factor is a single-chain polypeptide consisting of 53 amino acids with potent mitogenic activity that stimulates the proliferation of a range of normal and neoplastic cells through an interaction with its specific receptor (epidermal growth factor receptor, EGFR). This interaction plays a key role in tumor progression including the induction of tumor cell proliferation. An increased EGFR copy number have been associated with a favorable response to EGFR tyrosine kinase inhibitors therapy. In contrast, K-ras mutations tend to predict a poor response to such therapy. The aim of this study was to determine the correlation between the clinicopathological factors and the up-regulation of EGFR expression and Kras mutations in oral squamous cell carcinoma. Materials and Methods: This study examined the immunohistochemical staining of EGFR, K-ras mutation detection with peptide nucleic acid (PNA)-based real-time polymerase chain reaction (PCR) clamping in 20 specimens from 20 patients with oral squamous cell carcinoma. Results: 1. In the immunohistochemical study of poorly differentiated and invasive oral squamous cell carcinoma, a high level of EGFR staining was observed. The correlation between immunohistochemical EGFR expression and histological differentiation, as well as the tumor size of the specimens was significant (Pearson correlation analysis, significance [r] >0.5, P<0.05). 2. In PNA-based real-time PCR clamping analysis, a K-ras mutation was not detected in all specimens. Conclusion: These findings suggest that the up-regulation of the EGFR may play a role in the progression and invasion of oral squamous cell carcinoma that is, independent of a K-ras mutation.

• Parasites, Hosts and Diseases
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• v.54 no.1
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• pp.31-38
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• 2016

Specific gene expressions of host cells by spontaneous STAT6 phosphorylation are major strategy for the survival of intracellular Toxoplasma gondii against parasiticidal events through STAT1 phosphorylation by infection provoked $IFN-{\gamma}$. We determined the effects of small molecules of tyrosine kinase inhibitors (TKIs) on the growth of T. gondii and on the relationship with STAT1 and STAT6 phosphorylation in ARPE-19 cells. We counted the number of T. gondii RH tachyzoites per parasitophorous vacuolar membrane (PVM) after treatment with TKIs at 12-hr intervals for 72 hr. The change of STAT6 phosphorylation was assessed via western blot and immunofluorescence assay. Among the tested TKIs, Afatinib (pan ErbB/EGFR inhibitor, $5{\mu}M$) inhibited 98.0% of the growth of T. gondii, which was comparable to pyrimethamine ($5{\mu}M$) at 96.9% and followed by Erlotinib (ErbB1/EGFR inhibitor, $20{\mu}M$) at 33.8% and Sunitinib (PDGFR or c-Kit inhibitor, $10{\mu}M$) at 21.3%. In the early stage of the infection (2, 4, and 8 hr after T. gondii challenge), Afatinib inhibited the phosphorylation of STAT6 in western blot and immunofluorescence assay. Both JAK1 and JAK3, the upper hierarchical kinases of cytokine signaling, were strongly phosphorylated at 2 hr and then disappeared entirely after 4 hr. Some TKIs, especially the EGFR inhibitors, might play an important role in the inhibition of intracellular replication of T. gondii through the inhibition of the direct phosphorylation of STAT6 by T. gondii.

• Journal of Life Science
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• v.21 no.3
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• pp.349-357
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• 2011

Inhibitors of EGFR (epidermal growth factor receptor) kinase activity may prove useful to therapeutically intervene in cancer and to treat other proliferative diseases. In this study, we investigated the inhibitive effects of two compounds named 63013 and 63033 possess a [1,4]-dioxino quinazoline structure that links the alkoxy side chains together and their structural characteristics are considered to allow better solubility than the dialkoxyquinazoline derivatives. The EGFR kinase activities of A431 human epidermoid carcinoma cells, stimulated by EGF were inhibited by treatment with 63013 and 63033 in a dose-dependent manner respectively. Consistent with the compound-mediated EGFR kinase suppression, the major EGF-related downstream target molecules, such as MEK1/2, MAPK p44/42, AKT and STAT3, were also suppressed by both compounds. Interestingly, both compounds led to cell growth inhibition at a lower concentration than that of Gefitinib (Iressa$^{(R)}$). Collectively, our study showed that both compounds may have good therapeutic potential as an EGFR kinase specific inhibitor to treat EGFR-related diseases.

• Bulletin of the Korean Chemical Society
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• v.26 no.6
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• pp.959-965
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• 2005

Investigation of structure-activity relationships of novel quinazolines has identified 7,8-dihydro-[1,4]dioxino-[2,3-g]quinazolines as a potent inhibitor of EGFR. These compounds have a benzodioxane framwork, which was prepared by regioselective O-alkylation of ethyl 3,4-dihydroxy benzoate by epoxide ring opening. Compounds 3f and 3k were more potent than ZD-1839 in EGF enzyme and EGFR autophosporylation inhibition assays.

• Tuberculosis and Respiratory Diseases
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• v.80 no.2
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• pp.187-193
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• 2017

Background: Third-generation tyrosine kinase inhibitors of the epidermal growth factor receptor (EGFR-TKIs) have proved efficacious in treating non-small cell lung cancer (NSCLC) patients with acquired resistance resulting from the T790M mutation. However, since almost 50% patients with the acquired resistance do not harbor the T790M mutation, retreatment with first- or second-generation EGFR-TKIs may be a more viable therapeutic option. Here, we identified positive response predictors to retreatment, in patients who switched to a different EGFR-TKI, following initial treatment failure. Methods: This study retrospectively reviewed the medical records of 42 NSCLC patients with EGFR mutations, whose cancers had progressed following initial treatment with gefitinib or erlotinib, and who had switched to a different first-generation EGFR-TKI during subsequent retreatment. To identify high response rate predictors in the changed EGFR-TKI retreatment, we analyzed the relationship between clinical and demographic parameters, and positive clinical outcomes, following retreatment with EGFR-TKI. Results: Overall, 30 (71.4%) patients received gefitinib and 12 (28.6%) patients received erlotinib as their first EGFR-TKI treatment. Following retreatment with a different EGFR-TKI, the overall response and disease control rates were 21.4% and 64.3%, respectively. There was no significant association between their overall responses. The median progression-free survival (PFS) after retreatment was 2.0 months. However, PFS was significantly longer in patients whose time to progression was ${\geq}10months$ following initial EGFR-TKI treatment, who had a mutation of exon 19, or whose treatment interval was <90 days. Conclusion: In patients with acquired resistance to initial EGFR-TKI therapy, switched EGFR-TKI retreatment may be a salvage therapy for individuals possessing positive retreatment response predictors.

• 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.

• Analytical Science and Technology
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• v.22 no.6
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• pp.498-503
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• 2009

Lung cancer is the main cancer on the world today, due to the high case fatality. Lung cancer can devide into two major types, such as small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC). Mutations in the epidermal growth factor receptor (EGFR) have been described in patients with advanced NSCLC. Mutations in the EGFR are associated with clinical and radiographic responses to EGFR tyrosine kinase inhibitors gefitinib and erlotinib. Thus, the detection of EGFR mutation can offer an effective information in clinical decision-making. In this study, We developed very simple, cheep and rapid mutation detection system by chip-based isothermal amplification method. The method described here has shown the advantages of rapid amplification, high sensitivity, and specificity. Also, it will be useful for rapid and reliable clinical diagnosis of EGFR mutation.

• Tuberculosis and Respiratory Diseases
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• v.71 no.4
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• pp.286-290
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• 2011

Although failure of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKI) is generally believed to be associated with cross-resistance to other EGFR TKI, the benefit of administering erlotinib as a second EGFR TKI after resistance of gefitinib as the first TKI has been well known. However, good response to gefitinib after an initial response to erlotinib has been rare. We report that a 45-year-old woman (never smoked), with lung adenocarcinoma and EGFR mutation, showed an initial response to erlotinib, and then responded to gefitinib again.

• Natural Product Sciences
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• v.26 no.4
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• pp.345-350
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• 2020

In recent years, tyrosine kinases (TKs) have been the target to combat cancers, and most of the developed inhibitors are of synthetic origin. Natural compounds that have the properties as the TK's inhibitors are very limited. This paper described the isolation of a new dammarane triterpene from the tree bark of Sandoricum koetjape, along with three known related dammaranes from the damar resin of Shorea javanica, as well as their inhibitory properties against eight receptor TKs (RTKs: EGFR, HER2, HER4, IGF1R, InsR, KDR, PDGFRα, and PDGFRβ). Based on the NMR and mass spectral data the new compound was identified as (12β,20S)-12,20-dihydroxy-3,4-seco-dammaran-4,24-dien-3-oic acid (12β-hydroxydammarenolic acid) (1), while the three known compounds were identified as (20S)-20-hydroxy-3,4-seco-dammaran-4,24-dien-3-oic acid (dammarenolic acid) (2), (3β,20S)-3,20-dihydroxydammaran-24-ene (3), and (20S)-3-oxo-20-hydroxydammaran-24-ene (4). The tyrosine kinase assay of the four compounds resulted only 1 and 2 at concentration of 10 μM that had weak activity against EGFR and InsR, with their % inhibitory were 30%, 27% (1), 45%, and 32% (2), respectively. The results suggested that the presence of a linear carboxylic acid group in both compounds could be of significance to the inhibitory properties against the two RTKs.