• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.35 no.5
• /
• pp.287-293
• /
• 2009

Cell survival is the result of a balance between programmed cell death and cellular proliferation. Cell membrane receptors and their associated signal transducing proteins control these processes. Of the numerous receptors and signaling proteins, epidermal growth factor receptor (EGFR) is one of the most important receptors involved in signaling pathways implicated in the proliferation and survival of cancer cells. EGFR is often highly expressed in human tumors including oral squamous cell carcinomas, and there is increasing evidence that high expression of EGFR is correlated with poor clinical outcome of common human cancers. Therefore, we examined the antiproliferative activity of gefitinib, epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI), in head and neck cancer cell lines. SCC-9, KB cells were cultured and growth inhibition activity of gefitinib was measured with MTT assay. To study influence of gefitinib in cell cycle, we performed cell cycle analysis with flow cytometry. Western blot was done to elucidate the expression of EGFR in cell lines and phosphorylation of EGFR and downstream kinase protein, Erk and Akt. Significant growth inhibition was observed in SCC-9 cells in contrast with KB cells. Also, flow cytometric analysis showed G1 phase arrest only in SCC-9 cells. In Western blot analysis for investigation of EGFR expression and downstream molecule phosphorylation, gefitinib suppressed phosphorylation of EGFR and downstream protein kinase Erk, Akt in SCC-9. However, in EGFR positive KB cells, weak expression of active form of Erk and Akt and no inhibitory activity of phosphorylation in Erk and Akt was observed. The antiproliferative activity of gefitinib was not correlated with EGFR expression and some possibility of phosphorylation of Erk and Akt as a predictive factor of gefitinib response was emerged. Further investigations on more reliable predictive factor indicating gefitinib response are awaited to be useful gefitinib treatment in head and neck cancer patients.

• Tuberculosis and Respiratory Diseases
• /
• v.75 no.5
• /
• pp.188-198
• /
• 2013

Over the past decade, several kinase inhibitors have been approved based on their clinical benefit in cancer patients. Unfortunately, in many cases, patients develop resistance to these agents via secondary mutations and alternative mechanisms. To date, several major mechanisms of acquired resistance, such as secondary mutation of the epidermal growth factor receptor (EGFR) gene, amplification of the MET gene and overexpression of hepatocyte growth factor, have been reported. This review describes the recent findings on the mechanisms of primary and acquired resistance to EGFR tyrosine kinase inhibitors and acquired resistance to anaplastic lymphoma kinase inhibitors, primarily focusing on non-small cell lung carcinoma.

• Natural Product Sciences
• /
• v.27 no.2
• /
• pp.134-139
• /
• 2021

A new cipadesin limonoid, i.e. 3-epi-cipadonoid C (1), and a new tirucallane triterpene, i.e. hispidol B 3-palmitate (3), have been isolated from the seeds and fruit peels extract of Sandoricum koetjape, respectively. Along with these compounds the known limonoid, cipaferen G (2), and two pentacyclic triterpenes, bryonolic (4) and bryononic (5) acids, were also isolated. The strucrures of the new compounds were elucidated by the analysis of NMR and mass spectral data. Compounds 1 - 5 were evaluated as the inhibitor of receptor tyrosine kinases (EGFR, Epidermal Growth Factor Receptor; HER2, HER4, Human Epidermal growth factor Receptor 2, -4; IGFR, Insulin-like Growth Factor Receptor; InsR, Insulin Receptor; KDR, Kinase insert Domain Receptor; PDGFRα, and PDGFRβ, Platelet-Derived Growth Factor Receptor-α and -β). The results showed only 1 and 3 that have weak activity against InsR.

• Nuclear Medicine and Molecular Imaging
• /
• v.42 no.3
• /
• pp.185-191
• /
• 2008

While indirect targeting strategies using reporter-genes are taking center stage in current molecular imaging research, another vital strategy has long involved direct imaging of specific receptors using radiolabeled ligands. Recently, there is renewal of immense interest in this area with particular attention to the epidermal growth factor receptor (EGFR), a transmembrane glycoprotein critically involved in the regulation of many cellular functions and malignancies. Recently, two novel classes of EGFR-targeting anticancer drugs have entered clinical trials with great expectations. These are monoclonal antibodies such as cetuximab that target the extracellular domain, and small molecule tyrosine kinase inhibitors such as gefitinib (lressa) and erlotinib (Tarceva) that target the catalytic domain of the receptor. However, early results have showed disappointing survival benefits, disclosing a major challenge for this therapeutic strategy; namely, the need to identify tumors that are most likely to respond to the agents. To address this important clinical issue, several noninvasive imaging techniques are under investigation including radiolabeled probes based on small molecule tyrosine kinase inhibitors, anti-EGFR antibodies, and EGF peptides. This review describes the current status, limitations, and future prospects in the development of radiotracer methods for EGFR imaging.

• Journal of Digestive Cancer Research
• /
• v.1 no.1
• /
• pp.24-28
• /
• 2013

The five-year survival for patients with gastric cancer improved only modestly over the last 50 years. So, several studies about molecular target chemotherapy were investigated. We reviewed about molecular target chemotherapy for advanced unresectable and metastatic gastric cancer, which has developed recently. EGFR (Epidermal growth factor receptor), HER (Human epidermal growth factor receptor), VEGF (Vascular endothelial growth factor receptor) can be the target of therapy for gastric cancer. Patients with advanced gastric adenocarcinoma who are potential candidates for trastuzumab should have their tumors assayed for the presence of HER2 overexpression utilizing tumor-specific criteria and/or gene amplification. We suggest the addition of trastuzumab to chemotherapy in patients with HER2-positive tumors (as defined by 3+ immunohistochemical staining or FISH positivity), as long as they do not have a contraindication to trastuzumab. Except for trastuzumab, we summarized several studies for molecular target agents which were not validated yet.

• Tuberculosis and Respiratory Diseases
• /
• v.79 no.4
• /
• pp.248-256
• /
• 2016

Somatic mutations that lead to hyperactivation of epidermal growth factor receptor (EGFR) signaling are detected in approximately 50% of lung adenocarcinoma in people from the Far East population and tyrosine kinase inhibitors are now the standard first line treatment for advanced disease. They have led to a doubling of progression-free survival and an increase in overall survival by more than 2 years. However, emergence of resistant clones has become the primary cause for treatment failure, and has created a new challenge in the daily management of patients with EGFR mutations. Identification of mechanisms leading to inhibitor resistance has led to new therapeutic modalities, some of which have now been adapted for patients with unsuccessful tyrosine kinase inhibitor treatment. In this review, we describe mechanisms of tyrosine kinase inhibitor resistance and the available strategies to overcoming resistance.

• Journal of Gastric Cancer
• /
• v.4 no.4
• /
• pp.268-271
• /
• 2004

Purpose: Most gastrointestinal stromal tumors (GISTs) have gain-of-function mutations of the KIT or the platelet-derived growth factor receptor alpha (PDGFRA) genes, but approximately $10\%$ of the GISTs are wild types for both the KIT and the PDGFRA genes. The purpose of this study was to investigate the possibility that epidermal growth factor receptor (EGFR) gene mutation might be responsible for the pathogenesis of GIST. Materials and Methods: We analyzed the EGFR gene in 60 GISTs for the detection of somatic mutations by using the polymerase chain reaction (PCR), the single strand conformation polymorphism (SSCP), and DNA sequencing in exon 18, 19, and 21 encoding the kinase domain. Results: The SSCP analysis revealed no evidence of EGFR mutations in exon 18, 19, and 21 in GISTs. Conclusion: The data indicate that the EGFR gene may not be mutated in human GIST and suggest that therapies targeting the mutated EGFR gene products might not be useful in the treatment of GISTs.

• Korean Journal of Clinical Pharmacy
• /
• v.18 no.2
• /
• pp.75-83
• /
• 2008

Purpose: Currently lung cancer ranks second in cancer for incidence rate and is a disease that ranks first for a death rate by cancerous growth because it is already advanced at the time of diagnosis. The purpose of this paper was to analyze the factors that affect the effectiveness of and rash occurrence by Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor (EGFR TKI) in patients with non-small cell lung cancer. Methods: A retrospective chart review of 100 patients, who took EGFR TKI (erlotinib, gefitinib) among patients who were diagnosed with non-small cell lung cancer in a Hospital in Korea between May 2005 and February 2008, was conducted. The drug effectiveness was evaluated by Response Evaluation Criteria In Solid Tumor. Results: EGFR mutation was the only factor associated with drug response (complete response and partial response). When stable disease was added to drug response as the evaluation parameter, ECOG and rash as well as EGFR mutation were found to be important factors. Survival, however, was not affected by EGFR mutation. The factors influenced on survival were older age (${\geq}65$), low ECOG ($1{\sim}2$), adenocarcinoma and rash. In the case of rash, group with EGFR mutation or low ECOG showed significantly higher chance of occurrence. There was no significant difference in rash occurrence between gefitinib and erlotinib groups. Conclusions: Based on the results, EGFR mutation positive and low ECOG ($1{\sim}2$) were significantly important factors for both effectiveness of EGFR TKI and rash occurrence. Also, rash itself was found to be an independently significant factor for the disease control and survival. Therefore, while administering EGFR TKI, patients who have the factors associated with rash occurrence should be closely monitored for effective and safe drug therapy.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.10
• /
• pp.4879-4881
• /
• 2012

Epidermal growth factor receptor (EGFR) overexpression is associated with resistance to chemotherapy and radiotherapy. The EGFR modulates DNA repair after radiation-induced damage through an association with the catalytic subunit of DNA protein kinase. DNA double-strand breaks (DSBs) are the most lethal type of DNA damage induced by ionizing radiation, and non-homologous end joining is the predominant pathway for repair of radiation-induced DSBs. Some cell signaling pathways that respond to normal growth factors are abnormally activated in human cancer. These pathways also invoke the cell survival mechanisms that lead to resistance to radiation. The molecular connection between the EGFR and its control over DNA repair capacity appears to be mediated by one or more signaling pathways downstream of this receptor. The purpose of this mini-review was not only to highlight the relation of the EGFR signal as a regulatory mechanism to DNA repair and radiation resistance, but also to provide clues to improving existing radiation resistance through novel therapies based on the above-mentioned mechanism.

• Korean Journal of Head & Neck Oncology
• /
• v.15 no.2
• /
• pp.156-161
• /
• 1999

Objectives: The epidermal growth factor receptor(EGFR) family has been increasingly recognized as an important component in the control of normal cell proliferation and the pathogenesis of cancer. To confirm the usefulness of epidermal growth factor receptor as a tumor marker, we initiated this study. Materials and Methods: EGFR was measured by immunohistochemical staining using EGFR antibody. It was performed on section from paraffin blocks of 65 thyroid tissue including 33 paillary carcinoma, 11 follicular carcinoma, 11 nodular hyperplasia, 5 follicular adenoma and 5 normal thyroid tissue. We evaluated morphologic characteristic of various thyroid neoplasms, and the relationship between EGFR and other prognostic factors in papillary thyroid carcinomas. Results: The expression of EGFR was commonly found in neoplasms of thyroid, with trend for stronger staining in the more malignant tumor(p=0.000). Also the expression of EGFR in papillary thyroid cancer related to tumor characters including tumor size(p=0.042), extent(p=0.024) and prognostic features including AMES scores(p=0.019). The strong EGFR staining in papillary carcinoma was significantly associated with tumor recurrence(p=0.003). Conclusions: EGFR may have a role in the regulation of normal and neoplastic thyroid cell growth. EGFR status may help predict the clinical course of patients with malignant thyroid neoplasms. However, the study of more cases will be needed for significance of the information about the EGFR as an independent prognostic factor.