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PubMed2007

Gefitinib induces premature senescence in non-small cell lung cancer cells with or without EGFR gene mutation.

Despite its tremendous antitumor effect in a subset of patients with non-small cell lung cancer (NSCLC), the exact mechanism of gefitinib-induced cell death has not been fully determined. In this study, forms of cell death in various NSCLC cell lines after gefitinib exposure was analyzed to elucidate the cell death mechanism of gefitinib. Though higher concentration of gefitinib (10 microM) induced extensive apoptosis in two cell lines (EGFR-mutated PC-9 cells and EGFR wild- type EBC-2/R cells), clinically relevant concentrations of gefitinib (1 microM) induced prominent premature senescence instead of apoptosis in these cells. This induction of senescence was preceded by immediate increase of p16INK4A, p21WAF1/Cip1 and p27Kip1 levels and subsequent G1 cell cycle arrest. These phenomena were not observed in gefitinib-resistant (RERF-LC-MS) cells. Additionally, ex vivo exposure to gefitinib induced senescence in short-term cultured tumor cells that were obtained from malignant pleural effusion of a patient with NSCLC, whose tumor was later revealed to be clinically sensitive to gefitinib. Our results indicate that senescence might be a major anti-tumor mechanism of gefitinib in these NSCLC cells regardless of the EGFR gene mutation status.

Antineoplastic Agents↗

PubMed2004

Contrasting in vivo and in vitro fates of glioblastoma cell subpopulations with amplified EGFR.

Despite the high incidence of EGFR amplification in patient glioblastoma multiforme (GBM) tissues, only a single GBM cell line, of the many described in the literature, is known to contain and maintain amplified EGFR. Because EGFR mutations in GBM manifest primarily, if not exclusively, in amplified form, it follows that the availability of cell lines with mutation of endogenous EGFR would also be in short supply. In fact, there are no GBM cell lines harboring the common EGFR mutants described in patient GBMs. These observations suggest that in vivo environments select for EGFR amplification, whereas in vitro environments, specifically cell cultures, select against this gene alteration. To contrast directly the fates of EGFR amplification in vivo and in vitro, as well as to examine potential relationships between EGFR amplification and mutation, we have established and maintained GBM explants as xenografts by serial passaging in nude mice. Analysis of EGFR copy number and EGFR mutation status in 11 patient tumors and their corresponding xenografts, as well as the monitoring of EGFR copy number during the establishment of a GBM cell line from a xenograft with amplified EGFR, indicated that selection for EGFR amplification is an in vivo phenomenon. Furthermore, our data indicated that EGFR mutation occurs only in tumors with EGFR amplification and showed that the selection of amplified mutant EGFR over amplified wild-type EGFR as a xenograft occurred rapidly and completely during tumor propagation.

Animals↗

PubMed2006

Gefitinib for non-small-cell lung cancer patients with epidermal growth factor receptor gene mutations screened by peptide nucleic acid-locked nucleic acid PCR clamp.

This study was prospectively designed to evaluate a phase II study of gefitinib for non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations. Clinical samples were tested for EGFR mutations by peptide nucleic acid-locked nucleic acid PCR clamp, and patients having EGFR mutations were given gefitinib 250 mg daily as the second treatment after chemotherapy. Poor PS patients omitted chemotherapy. Of 107 consecutive patients enrolled, samples from 100 patients were informative, and EGFR mutations were observed in 38 patients. Gefitinib was given to 27 patients with EGFR mutations, and the response rate was 78% (one complete response and 20 partial responses; 95% confidence interval: 58-93%). Median time to progression and median survival time (MST) from gefitinib treatment were 9.4 and 15.4 months, respectively. Grade 3 hepatic toxicity and skin toxicity were observed in one patient each. There were significant differences between EGFR mutations and wild-type patients in response rates (78 vs 14%, P = 0.0017), and MST (15.4 vs 11.1 months, P = 0.0135). A Cox proportional hazards model indicated that negative EGFR mutation was a secondary prognostic factor (hazards ratio: 2.259, P = 0.036). This research showed the need for screening for EGFR mutations in NSCLC patients.

Adult↗

PubMed2026

Co-Occurring EGFR L858R Mutation and HER2 Amplification in NSCLC Identified by Stepwise Molecular Profiling.

BACKGROUND The coexistence of multiple oncogenic drivers in non-small cell lung cancer (NSCLC) is a rare and diagnostically challenging molecular configuration. Conventional polymerase chain reaction (PCR)-based testing may fail to detect co-occurring genomic alterations, potentially limiting therapeutic options, particularly in resource-constrained settings. CASE REPORT We describe the case of a 54-year-old non-smoking woman diagnosed with Stage IIIA lung adenocarcinoma in 2020. Initial PCR-based molecular testing was negative for EGFR mutations. Following disease progression with brain metastases and severe chemotherapy toxicity, stepwise molecular profiling in a resource-limited setting identified HER2 (ERBB2) amplification via fluorescence in situ hybridization (FISH). The patient achieved 23 months of clinical and radiological stabilization on trastuzumab. Subsequent next-generation sequencing (NGS) analysis of archived tissue revealed a previously undetected estimated glomular filtration rate (EGFR) L858R mutation. In late April 2025, new lesions appeared in the lungs, indicating disease progression. Based on the previously verified EGFR L858R mutation, the treatment strategy was revised and gefitinib was initiated in May 2025. CONCLUSIONS This case illustrates that co-occurring EGFR and HER2 alterations can remain undetected following initial limited molecular testing, and that stepwise molecular profiling in a resource-constrained setting can facilitate identification of therapeutically actionable targets. The sequential clinical responses observed are consistent with the biological relevance of both alterations, although broader conclusions regarding diagnostic strategy or driver hierarchy cannot be drawn from a single observation.

Humans↗

PubMed2006

High sensitivity detection of epidermal growth factor receptor mutations in the pleural effusion of non-small cell lung cancer patients.

Epidermal growth factor receptor (EGFR) mutations are a strong determinant of tumor response to gefitinib in non-small cell lung cancer (NSCLC). We attempted to elucidate the feasibility of EGFR mutation detection in cells of pleural effusion fluid. We obtained 24 samples of pleural effusion fluid from NSCLC patients. The pleural effusion fluid was centrifuged, and the cellular components obtained were used for detection. EGFR mutation status was determined by a direct sequencing method (exons 18-21) and by the Scorpion Amplified Refractory Mutation System (ARMS) method. EGFR mutations were detected in eight cases. Three mutations were detected by both methods, and the other five mutations were detected by Scorpion ARMS alone. The mutations were detected by both methods in all four partial responders among the seven patients who received gefitinib therapy. Direct sequencing detected the mutations in only two of four cases with partial response. These results suggest that the DNA in pleural effusion fluid can be used to detect EGFR mutations. The Scorpion ARMS method appears to be more sensitive for detecting EGFR mutations than the direct sequencing method.

Adult↗

PubMed2006

Clinical predictors versus epidermal growth factor receptor mutation in gefitinib-treated non-small-cell lung cancer patients.

BACKGROUND: Clinical predictors including Asian, female, adenocarcinoma and never-smoker and epidermal growth factor mutation are associated with gefitinib responsiveness in non-small-cell lung cancer. Direct comparison between clinical predictors and EGFR mutation for their predictive power has not been reported. PATIENTS AND METHODS: For 120 Korean NSCLC patients treated with gefitinib, we have analyzed EGFR mutational status in exons 18, 19 and 21. Patients were grouped according to the number of clinical predictors (female, adenocarcinoma and never-smoker). Response rate (RR), time-to-progression (TTP) and overall survival (OS) were analyzed. Multivariate analysis was performed to investigate which approach yielded better prediction. RESULTS: RRs according to number of clinical predictors were 0: 3.4%, 1: 17.1%, 2: 29.4% and 3: 33.3% (p=0.002). Patients with gefitinib-sensitive EGFR mutation showed 61.9% RR compared with 12.1% in the remaining patients (p<0.001). RRs were higher in patients with the EGFR mutations regardless of the number of clinical predictors. In multivariate analysis, gefitinib-sensitive EGFR mutation showed higher odds ratio of response (9.6, 95% confidence interval [CI] 3.2-28.7) compared with number of clinical predictors (1.7, 95% CI 1.1-2.7). Hazard ratio (HR) of TTP was also better in gefitinib-sensitive EGFR mutation (0.24, 95% CI 0.12-0.47) than number of clinical predictors (0.83, 95% CI 0.69-0.99). Only gefitinib-sensitive EGFR mutation was associated with improved OS (HR 0.25, 95% CI 0.12-0.52). CONCLUSION: EGFR mutation should be analyzed whenever possible for effective prediction of objective benefit from gefitinib in NSCLC patients with one or more clinical predictors.

Adenocarcinoma↗

PubMed2006

A phase II trial of gefitinib as first-line therapy for advanced non-small cell lung cancer with epidermal growth factor receptor mutations.

Retrospective analysis has shown that activating mutations in exons 18-21 of the epidermal growth factor receptor (EGFR) gene are a predictor of response to gefitinib. We conducted a phase II trial to evaluate the efficacy and safety of gefitinib as first-line therapy for advanced non-small cell lung cancer (NSCLC) with EGFR mutations. Patients with stage IIIB or IV chemotherapy-naïve NSCLC with EGFR mutation were treated with 250 mg gefitinib daily. For mutational analysis, DNA was extracted from paraffin-embedded tissues and EGFR mutations were analysed by direct sequence of PCR products. Twenty (24%) of the 82 patients analysed had EGFR mutations (deletions in or near E746-A750, n=16; L858R, n=4). Sixteen patients were enrolled and treated with gefitinib. Twelve patients had objective response and response rate was 75% (95% CI, 48-93%). After a median follow-up of 12.7 months (range, 3.1-16.8 months), 10 patients demonstrated disease progression, with median progression-free survival of 8.9 months (95% CI, 6.7-11.1 months). The median overall survival time has not yet been reached. Most of the toxicities were mild. This study showed that gefitinib is very active and well tolerated as first-line therapy for advanced NSCLC with EGFR mutations.

Administration, Oral↗

PubMed2005

Somatic mutations of EGFR gene in squamous cell carcinoma of the head and neck.

PURPOSE: Recently, the kinase domain mutations of epidermal growth factor receptor (EGFR) gene have been identified in non-small-cell lung cancer, and these mutations have been related to the clinical response to the tyrosine kinase inhibitor gefitinib. Gefitinib treatment has also shown clinical benefits in squamous cell carcinoma of the head and neck (SCCHN). The aim of this study was to explore the possibility that SCCHN harbored the EGFR mutations. EXPERIMENTAL DESIGN: In this study, we analyzed EGFR gene in 41 SCCHN for the detection of the somatic mutations by PCR-single-strand conformational polymorphism analysis. RESULTS: Overall, we detected three EGFR mutations (7.3%), and all of the mutations were the same in-frame deletion mutation in exon 19 (E746_A750del). CONCLUSION: These data indicated that in addition to non-small-cell lung cancer, SCCHN harbors the EGFR gene mutations, and suggested the rationale for the clinical applicability of gefinitib to SCCHN patients.

Adult↗

PubMed2005

Translational studies for target-based drugs.

The biological background for the clinical and prognostic heterogeneity among tumors within the same histological subgroup is due to individual variations in the biology of tumors. The number of investigations looking at the application of novel technologies within the setting of clinical trials is increasing. The most promising way to improve cancer treatment is to build clinical research strategies on intricate biological evidence. New genomic technologies have been developed over recent years. These techniques are able to analyze thousands of genes and their expression profiles simultaneously. The purpose of this approach is to discover new cancer biomarkers, to improve diagnosis, predict clinical outcomes of disease and response to treatment, and to select new targets for novel agents with innovative mechanisms of action. Gene expression profiles are also used to assist in selecting biomarkers of pharmacodynamic effects of drugs in the clinical setting. Biomarker monitoring in surrogate tissues may allow researchers to assess "proof of principle" of new treatments. Clinical studies of biomarkers monitoring toxicity profiles have also been done. Such pharmacodynamic markers usually respond to treatment earlier than clinical response, and as such may be useful predictors of efficacy. Epidermal growth factor receptor (EGFR) mutation in lung cancer tissues is a strong predictive biomarker for EGFR-targeted protein tyrosine kinase inhibitors. Monitoring of EGFR mutation has been broadly performed in retrospective and prospective clinical studies. However, global standardization for the assay system is essential for such molecular correlative studies. A more sensitive assay for EGFR mutation is now under evaluation for small biopsy samples. Microdissection for tumor samples is also useful for the sensitive detection of EGFR mutation. Novel approaches for the detection of EGFR mutation in other clinical samples such as cytology, pleural effusion and circulating tumor cells are ongoing.

Biomarkers, Tumor↗

PubMed2006

Exon 19 deletion mutations of epidermal growth factor receptor are associated with prolonged survival in non-small cell lung cancer patients treated with gefitinib or erlotinib.

PURPOSE: Somatic mutations in the epidermal growth factor receptor (EGFR) have been detected in patients with non-small cell lung cancer (NSCLC) and are associated with sensitivity to treatment with gefitinib or erlotinib. Our study explored the relationship between the two most common types of somatic EGFR mutations, exon 19 deletions and the L858R point mutation, and outcomes of patients following treatment with gefitinib or erlotinib. EXPERIMENTAL DESIGN: Tumor specimens obtained before treatment with gefitinib or erlotinib were analyzed for EGFR mutations. Patients with exon 19 deletion or L858R mutations were identified. The response rate, time to progression, and overall survival were determined for the two groups. RESULTS: We identified 36 patients with NSCLC and an EGFR mutation who were treated with gefitinib or erlotinib. Patients with an exon 19 deletion had a significantly longer overall survival compared with patients with an L858R mutation (38 versus 17 months; P = 0.04). There were also trends toward higher response rate (73% versus 50%) and improved time to progression (24 versus 10 months) for the patients with an exon 19 deletion, although these were not independently significant in a multivariate analysis. A difference in response rate for patients treated with gefitinib compared with erlotinib was also noted [18 of 23 (78%) versus 3 of 9 (33%); P = 0.04]. No obvious difference in time to progression or overall survival was noted between gefitinib- and erlotinib-treated patients. CONCLUSIONS: Patients with NSCLC and EGFR exon 19 deletions have a longer survival following treatment with gefitinib or erlotinib compared with those with the L858R mutation. Pooling of greater numbers of patients and completion of prospective trials are needed to further define the predictive and prognostic roles of different EGFR mutations with respect to treatment with gefitinib, erlotinib, and other EGFR inhibitors.

Adult↗

PubMed2006

Activation of the AKT and STAT3 pathways and prolonged survival by a mutant EGFR in human lung cancer cells.

To clarify the pathogenic and biological significance of EGFR mutations in lung cancer, we compared the status of ERBB family receptors, their downstream signal transductions and biological phenotypes between lung cancer cell lines with mutant and wild type EGFR. We initially analyzed expression and phosphorylation of ERBB family receptors and their major downstream proteins, AKT, p44/42 MAPK and STAT3, in a series of lung cancer cell lines with or without EGFR mutation. The expression levels of EGFR as well as of ERBB2 and ERBB3 proteins in cells with EGFR mutation tended to be higher than those in cells with wild type EGFR. There was no difference in stability between mutant and wild type EGFR proteins. EGF induced phosphorylation of EGFR, AKT, p44/42 MAPK and STAT3 to various extents, but the level of induction was not associated with the existence of EGFR mutation. These results implied that the activation of AKT, p44/42 MAPK and STAT3 signaling transmitted by EGFR would be critical for the growth and survival of lung cancer cells, but specific features of mutant EGFR in lung cancer cells was not discriminated by these approaches. We therefore performed transfection studies using PC-13 cells with no detectable endogenous EGFR expression. Exogenous expression of wild type and mutant EGFR (delE746-A750) in the cells revealed that only in the mutant EGFR transfected cells, EGFR itself as well as AKT and STAT3 were highly phosphorylated after 24h of serum deprivation. The survival time of mutant EGFR transfected cells was prolonged under serum-free culture conditions, but not under standard culture conditions with 10% serum. These results suggest that cells with a mutant EGFR survive through the activation of the AKT and/or STAT3 pathways, even in low EGF microenvironments. This specific property due to EGFR mutation could be an important step of multistage lung cancer progression.

Adenocarcinoma↗

PubMed2005

Mutations in the epidermal growth factor receptor gene are linked to smoking-independent, lung adenocarcinoma.

Epidermal growth factor receptor (EGFR) mutations are a potential predictor of the effectiveness of EGFR inhibitors for the treatment of lung cancer. Although EGFR mutations were reported to occur with high frequency in nonsmoking Japanese adenocarcinoma patients, the exact nature has not been fully elucidated. We examined EGFR gene mutations within exons 18-21 and their correlations to clinico-pathological factors and other genetic alterations in tumour specimens from 154 patients who underwent resection for lung cancer at Kyoto University Hospital. Epidermal growth factor receptor mutations were observed in 60 tumours (39.0%), all of which were adenocarcinoma. Among the patients with adenocarcinoma (n=108), EGFR mutations were more frequently observed in nonsmokers than former smokers or current smokers (83.0, 50.0, 15.2%, respectively), in women than men (76.3 vs 34.0%), in tumours with bronchio-alveolar component than those without bronchio-alveolar component (78.9 vs 42.9%), and in well or moderately differentiated tumours than poorly differentiated tumours (72.0, 64.4, 34.2%). No tumours with EGFR mutations had any K-ras codon 12 mutations, which were well-known smoking-related gene mutations. In conclusion, adenocarcinomas with EGFR mutation had a distinctive clinico-pathological feature unrelated to smoking. Epidermal growth factor receptor mutations may play a key role in the development of smoking-independent adenocarcinoma.

Adenocarcinoma↗

PubMed2006

A rapid and sensitive enzymatic method for epidermal growth factor receptor mutation screening.

PURPOSE: Mutations in the epidermal growth factor receptor (EGFR) are associated with clinical and radiographic responses to EGFR tyrosine kinase inhibitors gefitinib and erlotinib. Currently available methods of EGFR mutation detection rely on direct DNA sequencing, which requires isolation of DNA from a relatively pure population of tumor cells, cannot be done on small diagnostic specimens, and lack sensitivity. Here we describe the use of a sensitive screening method that overcomes many of these limitations. EXPERIMENTAL DESIGN: We screened 178 non-small cell lung cancer specimens for mutations in exons 18 to 21 of EGFR using a DNA endonuclease, SURVEYOR, which cleaves mismatched heteroduplexed DNA. Samples were analyzed by high-performance liquid chromatography on the Transgenomic WAVE HS system. Selected specimens that produced digestion products using SURVEYOR were subsequently reanalyzed by size separation or under partially denaturing conditions, followed by fractionation and sequencing. The specimens included DNA isolated from frozen tumor specimens, dissected formalin-fixed, paraffin-embedded tumor specimens undergoing clinical sequencing, and undissected formalin-fixed, paraffin-embedded specimens. One hundred sixty specimens were independently analyzed using direct DNA sequencing in a blinded fashion. RESULTS: EGFR mutations were detected in 16 of 61 fresh frozen tumor specimens, 24 of 91 dissected formalin-fixed, paraffin-embedded tumor specimens, and 11 of 26 undissected formalin-fixed, paraffin-embedded tumor specimens. Compared with sequencing, the sensitivity and specificity of the present method were 100% and 87%. The positive and negative predictive values were 74% and 100%, respectively. SURVEYOR analysis detected 7 (4%) mutations that were not previously detected by direct sequencing. CONCLUSIONS: SURVEYOR analysis provides a rapid method for EGFR mutation screening with 100% sensitivity and negative predictive value. This unbiased scanning technique is superior to direct sequencing when used with undissected formalin-fixed, paraffin-embedded specimens.

Carcinoma, Non-Small-Cell Lung↗

PubMed2006

Epidermal growth factor receptor kinase domain mutations in esophageal and pancreatic adenocarcinomas.

PURPOSE: Specific activating mutations within the epidermal growth factor receptor (EGFR) identify a subset of non-small cell lung cancers with dramatic sensitivity to the specific tyrosine kinase inhibitors (TKI), gefitinib and erlotinib. Despite the abundant expression of EGFR protein in a broad range of epithelial cancers, EGFR mutations have not been reported in a substantial fraction of other cancers. Given recent reports of TKI-responsive cases of esophageal and pancreatic cancer, this study was designed to determine the prevalence of EGFR mutations in these gastrointestinal cancers. EXPERIMENTAL DESIGN: We sequenced exons 18 to 21 of EGFR from 21 cases of Barrett's esophagus, 5 cases of high-grade esophageal dysplasia, 17 cases of esophageal adenocarcinoma, and 55 cases of pancreatic adenocarcinoma. Subsets of esophageal (n = 7) and pancreatic cancer cases (n = 5) were obtained from patients who were subsequently treated with gefitinib or erlotinib-capecitabine, respectively. RESULTS: Mutations of EGFR were identified in two esophageal cancers (11.7%), three cases of Barrett's esophagus (14.2%), and two pancreatic cancers (3.6%). The mutations consisted of the recurrent missense L858R and in-frame deletion delE746-A750, previously characterized as activating EGFR mutations in non-small cell lung cancer. We also identified the TKI drug resistance-associated EGFR T790M mutation in an untreated case of Barrett's esophagus and the corresponding adenocarcinoma. CONCLUSION: The presence of activating mutations within EGFR in both esophageal and pancreatic adenocarcinomas defines a previously unrecognized subset of gastrointestinal tumors in which EGFR signaling may play an important biological role. EGFR mutations in premalignant lesions of Barrett's esophagus also point to these as an early event in transformation of the esophageal epithelium. The role of genotype-directed TKI therapy should be tested in prospective clinical trials.

Adenocarcinoma↗

PubMed2025

Inherited rare epidermal growth factor receptor mutation and somatic mutations in patients with non-small cell lung cancer: a case report.

BACKGROUND: Recent advances in molecular oncology have increasingly illuminated the role of germline EGFR mutations in non-small cell lung cancer (NSCLC). This case report presents the presence of a unique familial occurrence of EGFR mutations in patients with NSCLC. CASE DESCRIPTION: A mother and son, both never-smokers of Caucasian ethnicity, were diagnosed with advanced metastatic lung adenocarcinoma. In one patient, tumor molecular analysis by next generation sequencing (NGS) identified two EGFR mutations: the activating mutation c.2573T > G; p.Leu858Arg (p.L858R) in exon 21 of the EGFR gene, and the somatic non-pathogenic mutation c.2612 C > A; p.Ala871Glu (p.A871E) in exon 21 of the EGFR gene. The second patient also harbored the same two EGFR mutations. The patient underwent genetic testing which revealed the germline origin of the A871E mutation. Whether the presence of this mutations was associated with increased predisposition to cancer has yet to be determined. Our case report highlights the need for further exploration of the role of germline mutations, including the A871E mutation, in tumorigenesis and its implications for treatment response and inheritance patterns. CONCLUSIONS: The investigation and comprehension of the significance of each individual EGFR mutation hold the promise for potential in cancer prevention or early diagnosis within family cohorts and understanding the mechanisms of tumorigenesis in sporadic cases.

Humans↗

PubMed2005

Predicting clinical benefit in non-small-cell lung cancer patients treated with epidermal growth factor tyrosine kinase inhibitors.

Erlotinib and gefitinib are small-molecule inhibitors of the epidermal growth factor tyrosine kinase. Erlotinib is approved for the treatment of locally advanced or metastatic non-small-cell lung cancer after failure of at least one prior chemotherapy regimen. Although it is active in unselected patients, clinical characteristics and tumor molecular markers associated with enhanced benefit have been identified. Notably, never-smoker status or a positive EGFR FISH test has been consistently predictive of greater erlotinib benefit. Other markers, such as EGFR mutations and EGFR protein expression, as determined by immunohistochemistry, and KRAS mutation status have not proven to be consistently associated with differential benefit.

Carcinoma, Non-Small-Cell Lung↗

PubMed2003

Serine mutations that abrogate ligand-induced ubiquitination and internalization of the EGF receptor do not affect c-Cbl association with the receptor.

In the present study, we examined EGF-induced internalization, degradation and trafficking of the epidermal growth factor receptor (EGFR) mutated at serines 1046, 1047, 1057 and 1142 located in its cytoplasmic carboxy-terminal region. We found the serine-mutated EGFR to be inhibited in EGF-induced internalization and degradation in NIH3T3 cells. We therefore tested the hypothesis that these mutations affect ligand-induced c-Cbl association with the receptor, leading to inhibited receptor ubiquitination. EGF was unable to induce ubiquitination of the serine-mutated EGFR, yet EGF-induced phosphorylation of the c-Cbl-binding site at tyrosine 1045, and c-Cbl-EGFR association, was unaffected. To compare the relevance of these serine residues with tyrosine 1045 in their regulation of c-Cbl binding and receptor ubiquitination, we analysed an EGFR mutated at tyrosine 1045 (Y1045F). EGF-induced c-Cbl-EGFR binding was partially inhibited, and receptor ubiquitination was abrogated in cells expressing Y1045F-EGFR. In contrast, ligand-induced internalization and degradation of the Y1045F mutant was similar to that of wild-type EGFR. Together, our data indicate that the serine residues and tyrosine 1045 are essential for EGF-induced receptor ubiquitination, but only the serine residues are critical for EGFR internalization and degradation.

Amino Acid Substitution↗

PubMed2005

Genetic heterogeneity of the epidermal growth factor receptor in non-small cell lung cancer cell lines revealed by a rapid and sensitive detection system, the peptide nucleic acid-locked nucleic acid PCR clamp.

Lung cancer is one of the leading causes of the cancer death worldwide. Gefitinib is an inhibitor of the tyrosine kinase activity of the epidermal growth factor receptor (EGFR) and has been introduced in the treatment of advanced lung cancers. The responsiveness to gefitinib has been linked to the presence of EGFR mutations. Clinical samples contain many normal cells in addition to cancer cells. A method capable of detecting EGFR mutations in a large background of wild-type EGFR genes could provide a superior clinical test. We developed a rapid and sensitive detection system for EGFR mutations named the peptide nucleic acid-locked nucleic acid (PNA-LNA) PCR clamp that can detect EGFR mutations in the presence of 100-to 1,000-fold background of wild-type EGFR. We used this method to screen 30 non-small cell lung cancer cell lines established from Japanese patients. In addition to 11 cell lines that have mutations, we found 12 cell lines in which specific mutations are observed only in the subpopulation(s) of the cells. Genetic heterogeneity of EGFR suggests that the EGFR gene is unstable in established cancers and the heterogeneity may explain variable clinical responses of lung cancers to gefitinib.

Antineoplastic Agents↗