Epidermal growth factor receptor family in lung cancer and premalignancy

Detection of epidermal growth factor receptor mutation in transbronchial needle aspirates of non-small cell lung cancer

BACKGROUND

Somatic mutations of epidermal growth factor receptor (EGFR) are closely associated with an objective response to EGFR tyrosine kinase inhibitors. However, it is difficult to obtain sufficient tumor samples from patients with non-small cell lung cancer (NSCLC), so these diagnoses are often made using cytology procedures alone. The aim of this study was to detect EGFR mutations in transbronchial needle aspiration (TBNA) samples using both direct sequencing and a highly sensitive assay (Scorpions Amplified Refractory Mutation System; DxS; Manchester, UK) [ARMS], and to compare the sensitivity of these methods.

METHODS

We enrolled 94 patients (63 men and 31 women) with NSCLC in this study. Cytologic diagnoses were adenocarcinoma (n = 58), squamous cell carcinoma (n = 24), and other types of NSCLC (n = 12). We extracted DNA from the TBNA samples, and EGFR mutations were analyzed using both direct sequencing (exons 19 and 21) and the Scorpions ARMS method (E746 A750del and L858R).

RESULTS

Mutations were detected in 31 patients (33%; 14 women and 17 men). Of these, 23 patients had adenocarcinoma, 4 had squamous cell carcinoma, and 4 had other types of NSCLC. Direct sequencing detected 13 mutations (14%) in 13 patients (E746-A750del, n = 6; L858R, n = 7), and the Scorpions ARMS method detected 27 mutations (29%) in 27 patients (E746 A750del, n = 16; L858R, n = 11 patients).

CONCLUSIONS

Both methods detected EGFR mutations in TBNA samples, but Scorpions ARMS is more sensitive than direct sequencing.

Inhibition of epidermal growth factor receptor signalling reduces hypercalcaemia induced by human lung squamous-cell carcinoma in athymic mice

The purpose of this study was to evaluate the role of the epidermal growth factor receptor (EGFR) in parathyroid hormone-related protein (PTHrP) expression and humoral hypercalcaemia of malignancy (HHM), using two different human squamous-cell carcinoma (SCC) xenograft models. A randomised controlled study in which nude mice with RWGT2 and HARA xenografts received either placebo or gefitinib 200 mg kg⁻¹ for 3 days after developing HHM. Effectiveness of therapy was evaluated by measuring plasma calcium and PTHrP, urine cyclic AMP/creatinine ratios, and tumour volumes. The study end point was at 78 h. The lung SCC lines, RWGT2 and HARA, expressed high levels of PTHrP mRNA as well as abundant EGFR protein, but very little erbB2 or erbB3. Both lines expressed high transcript levels for the EGFR ligand, amphiregulin (AREG), as well as, substantially lower levels of transforming growth factor-α (TGF-α), and heparin binding-epidermal growth factor (HB-EGF) mRNA. Parathyroid hormone-related protein gene expression in both lines was reduced 40–80% after treatment with 1 μM of EGFR tyrosine kinase inhibitor PD153035 and precipitating antibodies to AREG. Gefitinib treatment of hypercalcaemic mice with RWGT2 and HARA xenografts resulted in a significant reduction of plasma total calcium concentrations by 78 h. Autocrine AREG stimulated the EGFR and increased PTHrP gene expression in the RWGT2 and HARA lung SCC lines. Inhibition of the EGFR pathway in two human SCC models of HHM by an anilinoquinazoline demonstrated that the EGFR tyrosine kinase is a potential target for antihypercalcaemic therapy.

Tumor growth inhibition with cetuximab and chemotherapy in non-small cell lung cancer xenografts expressing wild-type and mutated epidermal growth factor receptor

PURPOSE

Targeting the epidermal growth factor receptor (EGFR) is a validated approach to treat cancer. In non-small cell lung cancer (NSCLC), EGFR contains somatic mutations in 10% of patients, which correlates with increased response rates to small molecule inhibitors of EGFR. We analyzed the effects of the monoclonal IgG1 antibody Erbitux (cetuximab) in NSCLC xenografts with wild-type (wt) or mutated EGFR.

EXPERIMENTAL DESIGN

NSCLC cell lines were grown s.c. in nude mice. Dose-dependent efficacy was established for cetuximab. To determine whether combination therapy produces tumor regressions, cetuximab was dosed at half-maximal efficacy with chemotherapy used at maximum tolerated dose.

RESULTS

Cetuximab showed antitumor activity in wt (A549, NCI-H358, NCI-H292) and mutated [HCC-827 (delE746-A750), NCI-H1975 (L858R, T790M)] EGFR-expressing xenografts. In the H292 model, cetuximab and docetaxel combination therapy was more potent to inhibit tumor growth than cetuximab or docetaxel alone. Cisplatin augmented efficacy of cetuximab to produce 6 of 10 regressions, whereas 1 of 10 regressions was found with cetuximab and no regression was found with cisplatin. Using H1975 xenografts, gemcitabine increased efficacy of cetuximab resulting in 12 of 12 regressions. Docetaxel with cetuximab was more efficacious with seven of nine regressions compared with single treatments. Cetuximab inhibited autophosphorylation of EGFR in both H292 and H1975 tumor lysates. Exploring the underlying mechanism for combination effects in the H1975 xenograft model, docetaxel in combination with cetuximab added to the antiproliferative effects of cetuximab but was the main component in this drug combination to induce apoptosis.

CONCLUSIONS

Cetuximab showed antitumor activity in NSCLC models expressing wt and mutated EGFR. Combination treatments increased the efficacy of cetuximab, which may be important for the management of patients with chemorefractory NSCLC.

WWOX expression in different histologic types and subtypes of non-small cell lung cancer

PURPOSE

Non-small cell lung cancer (NSCLC) has heterogeneous histopathologic classification and clinical behavior and very low survival rate. WWOX (WW domain-containing oxidoreductase) is a tumor suppressor gene, and its expression is altered in several cancers. The purpose of this study is to better define the role of WWOX in NSCLC tumorigenesis and progression by determining its pathogenetic and prognostic significance.

EXPERIMENTAL DESIGN

WWOX protein expression was evaluated by immunohistochemistry in 170 patients with NSCLC (101 squamous cell carcinomas, 66 adenocarcinomas, 3 large cell carcinomas) and was correlated with histopathologic (histotype, subtype, grade, tumor-node-metastasis, stage, index of cell proliferation Ki67/MIB1) and clinical (age, gender, local recurrences, distant metastases, overall survival, and disease-free survival) characteristics.

RESULTS

WWOX expression was absent/reduced in 84.9% of NSCLCs, whereas it was normal in 80.5% of adjacent normal lung tissues. WWOX expression was strongly associated with tumor histology (P=1.1x10(-5)) and histologic grade (P=0.0081): the percentage of cases with absent/strongly reduced WWOX expression was higher in squamous cell carcinomas and in poorly differentiated tumors. Regarding adenocarcinoma, bronchioloalveolar pattern showed normal WWOX expression in 62.5% of the cases, whereas in solid and acinar patterns, a prevalence of cases with absent/very low WWOX expression was observed (79.2% and 50%, respectively). Finally, weak WWOX staining intensity was related to the high index of cell proliferation (P=0.0012).

CONCLUSIONS

Our results suggest that the loss of WWOX expression plays different roles in tumorigenesis of distinct histotypes and subtypes of NSCLC and is related to high aggressiveness (G3; high proliferating activity) of tumors.

A translational view of the molecular pathogenesis of lung cancer

Molecular genetic studies of lung cancer have revealed that clinically evident lung cancers have multiple genetic and epigenetic abnormalities, including DNA sequence alterations, copy number changes, and aberrant promoter hypermethylation. Together, these abnormalities result in the activation of oncogenes and inactivation of tumor-suppressor genes. In many cases these abnormalities can be found in premalignant lesions and in histologically normal lung bronchial epithelial cells. Findings suggest that lung cancer develops through a stepwise process from normal lung epithelial cells towards frank malignancy, which usually occurs as a result of cigarette smoking. Lung cancer has a high morbidity because it is difficult to detect early and is frequently resistant to available chemotherapy and radiotherapy. New, rationally designed early detection, chemoprevention, and therapeutic strategies based on the growing understanding of the molecular changes important to lung cancer are under investigation. For example, methylated tumor DNA sequences in sputum or blood are being investigated for early detection screening, and new treatments that specifically target molecules such as vascular endothelial growth factor and the epidermal growth factor receptor are becoming available. Meanwhile, global gene expression signatures from individual tumors are showing potential as prognostic and therapeutic indicators, such that molecular typing of individual tumors for therapy selection is not far away. Finally, the recent development of a model system of immortalized human bronchial epithelial cells, along with a paradigm shift in the conception of cancer stem cells, promises to improve the situation for patients with lung cancer. These advances highlight the translation of molecular discoveries on lung cancer pathogenesis from the laboratory to the clinic.

Gefitinib and chemotherapy combination studies in five novel human non small cell lung cancer xenografts. Evidence linking EGFR signaling to gefitinib antitumor response

The epidermal growth factor receptor (EGFR) signaling pathway is often activated in NSCLC, and thus represents a promising therapeutic target. We studied the antitumor activity of gefitinib (Iressa), an orally active EGFR-tyrosine kinase inhibitor, alone and in combination with standard chemotherapy in 5 recently established human NSCLC xenografts with wild-type EGFR. Mice were treated with 2 protocols of chemotherapy based on cisplatin (CDDP) combined with either gemcitabine (GEM) or vinorelbine (VNR). Gefitinib alone significantly inhibited tumor growth (TGI) in 4 of the 5 tumor xenografts (mean TGI of 58%, range: 25-70%). CDDP+VNR alone failed to achieve any significant responses, while CDDP+GEM achieved significant responses in 2 xenografts (TGI of 93 and 47%). Addition of gefitinib to CDDP+GEM potentialized chemotherapy in the 3 CDDP+GEM-resistant xenografts, but did not potentialize the CDDP+VNR combination. The effect of gefitinib treatment on the activity of extra cellular-regulated kinase (Erk), Akt, JNK and p38 kinases was assessed in IC9LC11 and IC1LC131, two NSCLC xenografts selected for their sensitivity and resistance to gefitinib, respectively. In IC9LC11, gefitinib strongly inhibited Erk, Akt and Jnk phosphorylation, but P38 remained active. Inversely, in IC1LC131, Erk and Akt pathways remained active, while Jnk and P38 pathways were inhibited by gefitinib. The data indicate that the antitumor activity of gefitinib in NSCLC, alone or in combination with chemotherapy, is tumor-dependent and is influenced by downstream signaling events independent of EGFR status.

Novel therapies targeting signaling pathways in lung cancer

Despite advances in chemotherapy, the prognosis for advanced non-small-cell lung cancer (NSCLC) remains dismal. Increasing understanding of the biological processes responsible for lung carcinogenesis has led to development of new therapeutic strategies targeting this disease at a molecular level. This article examines the molecular events believed to lead to cellular changes in lung cancer, and how knowledge of these is used to develop new agents used individually or in combination with available cytotoxic drugs to improve survival. Finally, it explores how a deeper understanding of the embryonic signaling pathways responsible for airway epithelial repair and tumorogenesis, such as Hedgehog (Hh), Notch, and Wingless (Wnt), can lead to the development of newer and more specific therapies for lung cancer.

Epidermal growth factor receptor abnormalities in lung cancer. Pathogenetic and clinical implications

The discovery that mutation of the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) gene occurs in a subset of lung cancers and predicts for sensitivity to tyrosine kinase inhibitors has generated enormous interest and immediately led to intense basic, translational, and clinical research in many laboratories around the globe. All these findings have led to the identification of a subset of lung cancers with relatively distinct molecular, pathologic, and clinical features that demonstrate response to targeted therapy. Currently, the best marker to predict response and better survival for EGFR tyrosine kinase inhibitors, such as EGFR mutation, gene increased copy number, and protein immunohistochemical expression, is still controversial. Importantly, the findings of EGFR abnormalities in lung cancer have supported the notion that different molecular mechanisms and pathways are involved in the pathogenesis of lung cancer arising in never and ever smokers.

EGFR mutation status in tumour-derived DNA from pleural effusion fluid is a practical basis for predicting the response to gefitinib

Epidermal growth factor receptor (EGFR) mutations are strong determinants of tumour response to EGFR tyrosine kinase inhibitors in non-small-cell lung cancer (NSCLC). Pleural effusion is a common complication of lung cancer. In this study, we assessed the feasibility of detection of EGFR mutations in samples of pleural effusion fluid. We obtained 43 samples, which was the cell-free supernatant of pleural fluid, from Japanese NSCLC patients, and examined them for EGFR mutations. The epidermal growth factor receptor mutation status was determined by a direct sequencing method (exons 18–21 in EGFR). EGFR mutations were detected in 11 cases (E746_A750del in seven cases, E746_T751del insA in one case, L747_T751del in one case, and L858R in two cases). The EGFR mutations were observed more frequently in women and non-smokers. A comparison between the EGFR mutant status and the response to gefitinib in the 27 patients who received gefitinib revealed that all seven patients with partial response and one of the seven patients with stable disease had an EGFR mutation. No EGFR mutations were detected in the patients with progressive disease. The results suggest that DNA in pleural effusion fluid can be used to detect EGFR mutations and that the EGFR mutation status may be useful as a predictor of the response to gefitinib.

Targeted therapy in advanced non-small cell lung cancer (NSCLC): where do we stand?

Cytotoxic chemotherapy has helped improve the outcomes in patients with advanced non-small cell lung cancer (NSCLC), but we seem to have reached a plateau with respect to the benefit obtained. Also, a large subset of elderly patients and those with a poor performance status cannot tolerate these drugs at recommended doses. There is a growing need to incorporate newer drugs with different mechanisms of action and better safety profile. The epidermal growth factor receptor family (EGFR) and vascular endothelial growth factor (VEGF) have been identified as potential targets and agents acting specifically against these targets have been developed with the hope of improving outcomes. Although recent data with the small molecule EGFR tyrosine kinase inhibitors have been disappointing, there have been instances of dramatic responses thereby raising questions about the ideal patient to whom these drugs should be administered. Cetuximab, the anti-EGFR antibody has shown promising results. Bevacizumab, the anti-VEGF antibody was the first drug to demonstrate a survival benefit in first line treatment when added to chemotherapy. This review will briefly discuss the important trials using these targeted agents in advanced NSCLC.

Lung adenocarcinoma harboring mutations in the ERBB2 kinase domain

Mutations in the ERBB2kinase domain have been reported in non-small cell lung cancer (NSCLC). Here, we describe a detailed search for ERBB2 gene mutations in tumors derived from NSCLC patients. Tumor specimens from 223 patients who underwent resection for NSCLC were examined for the presence of mutations in exons 19 and 20 of the ERBB2gene. Correlations were then made between the expression of these mutations and the clinical characteristics of the patients from which they were derived as well as the tumor's pathological features. ERBB2mutations were observed in four of the above tumors (1.8%), all of which were adenocarcinomas. All ERBB2mutations were in-frame insertions that occurred in exon 20. The patients from whom these tumors were derived were nonsmokers. Three of the tumors were of the papillary subtype, and one was a mixed subtype that consisted of acinar, papillary, and solid components. None of the tumors had a bronchio-alveolar component nor did they have epidermal growth factor receptoror K-rascodon 12 mutations. In conclusion, patients with these tumors tended to be nonsmokers who had clinical features similar to those of lung cancer patients whose tumors expressed epidermal growth factor receptormutations, although their tumors showed slightly different pathological features.

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.

The complexity of targeting EGFR signalling in cancer: from expression to turnover

The epidermal growth factor receptor (ErbB1 or EGFR) has been found to be altered in a variety of human cancers. A number of agents targeting these receptors, including specific antibodies directed against the ligand-binding domain of the receptor and small molecules that inhibit kinase activity are either in clinical trials or are already approved for clinical treatment. However, identifying patients that are likely to respond to such treatments has been challenging. As a consequence, it still remains important to identify additional alterations of the tumor cell that contribute to the response to EGFR-targeted agents. While EGFR-mediated signalling pathways have been well established, there is still a rather limited understanding of how intracellular protein-protein interactions, ubiquitination, endocytosis and subsequent degradation of EGFR contribute to the determination of sensitivity to EGFR targeting agents and are emerging areas of investigation. This review primarily focuses on the basic signal transduction pathways mediated through activated membrane bound and/or endosomal EGFR and emphasizes the need to co-target additional proteins that function either upstream or downstream of EGFR to improve cancer therapy.

Is Quantitative Real-Time RT-PCR an Adjunct to Immunohistochemistry for the Evaluation of ErbB2 Status in Transitional Carcinoma of the Bladder?

OBJECTIVE

To test different approaches of evaluation of the ErbB2 status in a large series of human transitional cell carcinoma (TCC) of the bladder with the prospect of finding targeted therapies.

METHODS

ErbB2 status of 73 human TCC samples was analyzed by both immunohistochemistry (IHC) and by quantification of mRNA levels of expression using real-time reverse transcription-polymerase chain reaction (RT-PCR). Additionally, 18 bladder samples were studied for ERBB2 gene amplification by real-time quantitative PCR.

RESULTS

Twenty-five tumors (34.2%) overexpressed ERBB2 mRNA compared to normal bladder samples; this alteration appeared in low-grade and low-stage tumors (pTaG1). Twenty-four (32.9%) tumors showed moderate (++) or strong (+++) immunostaining. A very strong agreement was found between the two methods (kappa = 0.97, 95% confidence interval, 0.90-1). ErbB2 status was not associated with tumor stage. Of the 18 bladder samples tested for ERBB2 gene amplification, only one showed ERBB2 DNA amplification.

CONCLUSIONS

ErbB2 overexpression occurs in about one third of bladder TCCs. This overexpression can be detected by RT-PCR with a very good correlation with IHC. RT-PCR can therefore be used for cases considered doubtful on IHC rather than gene amplification studies because, in TCC, gene amplification is not the predominant mechanism of both mRNA and protein overexpression. Accurate quantification of ErbB2 status is mandatory for the use of anti-ErbB2-targeted therapies in bladder TCC.

Arsenic in the aetiology of cancer

Arsenic, one of the most significant hazards in the environment affecting millions of people around the world, is associated with several diseases including cancers of skin, lung, urinary bladder, kidney and liver. Groundwater contamination by arsenic is the main route of exposure. Inhalation of airborne arsenic or arsenic-contaminated dust is a common health problem in many ore mines. This review deals with the questions raised in the epidemiological studies such as the dose-response relationship, putative confounders and synergistic effects, and methods evaluating arsenic exposure. Furthermore, it describes the metabolic pathways of arsenic, and its biological modes of action. The role of arsenic in the development of cancer is elucidated in the context of combined epidemiological and biological studies. However, further analyses by means of molecular epidemiology are needed to improve the understanding of cancer aetiology induced by arsenic.

Epidermal Growth Factor Receptor Exposed to Oxidative Stress Undergoes Src- and Caveolin-1-dependent Perinuclear Trafficking

The epidermal growth factor (EGF) receptor (EGFR) has been found to be overexpressed in several types of cancer cells, and the regulation of its oncogenic potential has been widely studied. The paradigm for EGFR down-regulation involves the trafficking of activated receptor molecules from the plasma membrane, through clathrin-coated pits, and into the cell for lysosomal degradation. We have previously shown that oxidative stress generated by H2O2 results in aberrant phosphorylation of the EGFR. This leads to the loss of c-Cbl-mediated ubiquitination of the EGFR and, consequently, prevents its degradation. However, we have found that c-Cbl-mediated ubiquitination is required solely for degradation but not for internalization of the EGFR under oxidative stress. To further examine the fate of the EGFR under oxidative stress, we used confocal analysis to show that the receptor not only remains co-localized with caveolin-1 at the plasma membrane, but at longer time points, is also sorted to a perinuclear compartment via a clathrin-independent, caveolae-mediated pathway. Our findings indicate that although the EGFR associates with caveolin-1 constitutively, caveolin-1 is hyperphosphorylated only under oxidative stress, which is essential in transporting the EGFR to a perinuclear location, where it is not degraded and remains active. Thus, oxidative stress may have a role in tumorigenesis by not only activating the EGFR but also by promoting prolonged activation of the receptor both at the plasma membrane and within the cell.

Laminin alpha2 chain-positive vessels and epidermal growth factor in lung neuroendocrine carcinoma: a model of a novel cooperative role of laminin-2 and epidermal growth factor in vessel neoplastic invasion and metastasis

Capillaries expressing the laminin alpha2 chain in basement membranes may be considered early developing vessels in normal and neoplastic human tissues. Therefore, we investigated whether up-regulation of this extracellular matrix protein favors transendothelial migration of neoplastic cells and then metastasis. In lung small and large cell neuroendocrine carcinomas, which exhibit a stronger metastatic tendency among carcinomas, laminin alpha2 chain-positive vessels were more numerous than in carcinoid tumors and supraglottis, breast, and lung non-small cell carcinomas, suggesting a direct relationship between these vessels and metastasis. In vitro studies showed that epidermal growth factor (EGF) induced a more efficient migration of the AE-2 lung neuroendocrine carcinoma cell line through the purified laminin alpha2 chain rather than through the laminin beta1 chain and fibronectin. AE-2 cells constitutively expressed all EGF receptors and the alpha6beta1 integrin, which is one of the laminin alpha2 chain receptors. EGF up-regulated alpha6beta1 expression in several tumors. In this regard, we show that EGF increased the chemo-kinetic migration of AE-2 cells through EAHY endothelial monolayers, which was inhibited by the anti-alpha6 integrin chain monoclonal antibody. These data indicate that laminin alpha2 chain and alpha6beta1 may be mutually involved in EGF-dependent migration of AE-2 cells and that laminin alpha2 chain-positive vessels may favor metastasis of EGF-dependent tumors.

Epidermal growth factor receptor mutations in non-small cell lung cancer: a basic science discovery with immediate clinical impact

A large body of preclinical work suggested that the epidermal growth factor receptor (EGFR) would be a successful target for therapy against non-small cell lung cancer (NSCLC), and this led to the development of oral, selective EGFR tyrosine kinase inhibitors (TKI) that improve symptoms and survival in patients with advanced NSCLC. However, not all patients benefit from this treatment, and there has been great interest in identifying the molecular correlates that predict for response to these agents. The recent detection of somatic mutations in EGFR that predict for response to the EGFR tyrosine kinase inhibitors has excited the scientific community. This discovery has far-reaching implications, not only for lung cancer patients treated with an EGFR TKI but also for future drug development in all malignancies.

EGFR-Expression in pulmonalen neuroendokrinen Zellhyperplasien

15 cases of pulmonary neuroendocrine cell hyperplasia (carcinoid-tumorlets, diffuse idiopathic pulmonary neuroendocrine cell hyperplasia/DIPNECH) and 20 neuroendocrine pulmonary tumors (10 carcinoid tumors, 5 large cell neuroendocrine, and 5 small cell neuroendocrine lung carcinomas) were immunohistochemically analyzed for the expression of epidermal growth factor receptor (EGFR, = HER-1). All cases of neuroendocrine cell hyperplasia exhibited a maximum EGFR expression (score 3 in 100% of cells) showing predominantly membranous, partly cytoplasmic staining. 4 ot the 10 carcinoid tumors were strongly positive for EGFR, whereas the other 6 were EGFR-negative. A total of 90% of large cell neuroendocrine and small cell neuroendocrine carcinomas were negative for EGFR. Overexpression of EGFR in pulmonary neuroendocrine cell hyperplasia might be significant for the pathogenesis of these lesions. As DIPNECH is characterized by clinical signs and symptoms including mild cough and obstructive functional impairment, a specific antagonistic therapeutic trial could aim at blocking EGFR/HER-1 or its subsequent signal transduction pathway.

Molecular regulation of tumor angiogenesis: mechanisms and therapeutic implications

Angiogenesis, the process of new capillary formation from a pre-existing vessel plays an essential role in both embryonic and postnatal development, in the remodeling of various organ systems, and in several pathologies, particularly cancer. In the last 20 years of angiogenesis research, a variety of angiogenic regulators, both positive and negative, have been identified. The discovery of several anti-angiogenic factors has led to the development of novel cancer therapies based on targeting a tumor's vascular supply. A number of these new therapies are currently being tested in clinical trials in the U.S.A. and elsewhere. A major advance in the field of anti-angiogenic therapy occurred recently when the FDA approved Avastin (bevacizumab), the first solely anti-angiogenesis therapy approved for treatment of human cancer. While it has long been appreciated that tumor growth and progression are dependent on angiogenesis, it is only recently that progress has been made in elucidating the molecular mechanisms that regulate the earliest stage in the angiogenic program, the angiogenic switch. This checkpoint is characterized by the transition of a dormant, avascular tumor into an active, vascular one. Anti-angiogenic therapies to date have essentially been designed to suppress the neovasculature in established tumors. However, identifying the mechanisms that cause a tumor to acquire an angiogenic phenotype may lead to the discovery of new therapeutic modalities and complementary diagnostics that could be used to block the angiogenic switch, thereby preventing subsequent tumor progression. In this chapter on the role of angiogenesis in cancer, we (1) provide an overview of the process of angiogenesis with special regard to the molecules and physiological conditions that regulate this process, (2) review recent studies describing the use of anti-angiogenic approaches in the treatment of a variety of human cancers, and (3) discuss the recent literature focused on the study of the molecules and molecular mechanisms that may be regulating the initiation of the angiogenic phenotype in tumors, and the clinical impact that this knowledge may have in the future.

Targeting EGFR and HER-2 receptor tyrosine kinases for cancer drug discovery and development

Conventional anticancer therapy using cytotoxic drugs lacks selectivity and is prone to toxicity and drug resistance. Anticancer therapies targeting aberrant growth factor receptor signaling are gaining interest. The erbB receptor family belongs to the type I, the receptor tyrosine kinases class, and comprises EGFR, HER-2, HER-3, and HER-4. It has been targeted for solid tumor therapy, including breast, ovarian, colon, head-and-neck, and non-small-cell lung cancers. This review summarizes structural aspects of this class of growth factor receptors, their oncogenic expression, and various pharmacological interventions including biological products and small molecules that inhibit these enzymes. We have also discussed various mutations that occur in EGFR and their consequences on anticancer therapy.

Microsatellite polymorphisms in the epidermal growth factor receptor (EGFR) gene and the transforming growth factor-alpha (TGFA) gene and risk of oral cancer in Puerto Rico

OBJECTIVES AND METHODS

Risks of oral cancer related to a CA microsatellite repeat polymorphism in intron 1 of the epidermal growth factor receptor (EGFR) gene and a TaqI polymorphism in the transforming growth factor-alpha (TGFA) gene were evaluated in a population-based case-control study consisting of 157 cases and 149 controls recruited in Puerto Rico.

RESULTS

Carriers of > or = 16 CA repeats in EGFR showed a 1.9-fold increased risk for oral cancer (OR=1.9, 95% CI=1.0-3.5). Risks also tended to increase with decreasing number of alleles with > or = 16 CA repeats (P for trend=0.06). Our data suggested a non-significant reduction in risk for subjects heterozygous for the TGFA polymorphism (OR=0.6, 95% CI=0.2-1.3).

CONCLUSIONS

The EGFR-associated risk appeared to be independent of tobacco and alcohol use and may be restricted primarily to subjects who consumed low amounts of fresh fruits and vegetables (OR=5.9, 95%CI: 2.3-15.2). These data implicate dietary and molecular targets for oral cancer prevention.

Plasma MIP-1β levels and skin toxicity in Japanese non-small cell lung cancer patients treated with the EGFR-targeted tyrosine kinase inhibitor, gefitinib

Gefitinib (Iressa() is an orally active, selective EGFR tyrosine kinase inhibitor that blocks signal transduction pathways. Skin toxicity has been reported to be the major toxicity observed in patients treated with the EGFR-targeted tyrosine kinase inhibitors, such as gefitinib and erlotinib. Although the mechanisms underlying the development of the skin toxicity remain to be precisely clarified, immunological mechanisms are considered to be involved. We examined the correlations between the plasma levels of several cytokines and the risk of development of adverse events, especially skin toxicity, induced by the administration of gefitinib as first-line monotherapy in non-small cell lung cancer (NSCLC) patients. Paired plasma samples were obtained from a total 28 patients of non-small cell lung cancer; the first before the initiation of gefitinib administration (250 mg/day) (24 patients) and the second 2 or 4 weeks after the initiation of treatment (23 patients). The plasma concentrations of 17 major cytokines were measured using a bead-based multiplex assay. The median concentrations of eight of these cytokines before the start of treatment ranged from 0.06 (IL-5) to 58.26 (MIP-1beta) (microg/ml). The concentrations of the remaining nine cytokines were under the detectable limit (<0.01 microg/ml) in more than 50% of the samples. Comparisons of the levels before and after treatment showed no significant differences for any of the cytokines measured. The MIP-1beta levels were significantly lower in the patients with skin toxicity (16/24) as compared with those in the patients not showing any skin toxicity (59.1+/-10.5 versus 119.0+/-36.8; p=0.042 by the two-sample t-test). The K-Nearest Neighbor Prediction (K=3) showed the classification rate to be 75% for the prediction sets containing MIP-1beta, IL-4 and IL-8. There were no significant associations between the levels of any of the cytokines measured and any other parameters, including the tumor response to the drug. In conclusion, the plasma MIP-1beta level may be a useful predictor of the development of skin toxicity in patients receiving gefitinib treatment.

Differential expression of biomarkers in lung adenocarcinoma: a comparative study between smokers and never-smokers

BACKGROUND

Non-small-cell lung cancer arising in never-smokers is usually of adenocarcinoma subtype. The oncogenic pathway of such tumors is poorly understood. To better define the biological characteristics of these tumors, we have compared the expression of a panel of epidermal growth factor receptor (EGFR)-related biomarkers in lung adenocarcinomas from smokers versus those in never-smokers.

PATIENTS AND METHODS

Using immunohistochemical analysis, we retrospectively analyzed EGFR, pAKT, PTEN, Ki-67, p27 and hTERT expression in specimens from 190 patients with completely resected lung adenocarcinomas (43 never-smokers and 147 smokers). These analyses were performed on tissue microarrays.

RESULTS

EGFR expression was higher in tumors from smokers (P < 0.01), while pAKT was overexpressed mainly in tumors from never-smokers (P = 0.01). As expected, the tumors from smokers presented a higher expression of Ki-67 and a more frequent loss of expression of p27 (P < 0.01). In a multivariate model, two biological factors (p27 and Ki-67) and two clinical factors (age and sex) showed independent significant correlation with never-smoking status.

CONCLUSIONS

Lung adenocarcinomas in never-smokers have a very distinct immunohistochemical expression profile of EGFR-related biomarkers as compared with lung adenocarcinomas in smokers. High levels of EGFR and Ki-67 are observed in smokers, while never-smokers are characterized by high levels of pAKT and p27.

Chemoprevention in lung carcinogenesis--an overview

Lung cancer ranks among the most commonly occurring malignancies and is currently the leading cause of cancer-related death worldwide. This is due to its late diagnosis and relative resistance to standard oncological treatment approaches. The heavy burden of lung cancer and its treatment resistance have elicited an intense interest in the promising approach of chemoprevention. Chemoprevention is defined as a pharmacologic intervention to suppress or reverse the carcinogenic process and the lung is one of the most studied sites for cancer chemoprevention. This review, with a short update on pulmonary carcinogenesis, will summarize the available knowledge of chemoprevention trials and agents with a preventive potential in the 'lung field'.

Molecular pathology of non-small-cell lung cancer

The molecular basis of lung carcinogenesis must be understood more fully and exploited to enhance survival rates of patients suffering from lung cancer. In this review we will discuss the major molecular alterations that occur in lung cancer. Emphasis is placed on alterations that occur early during carcinogenesis since they might be relevant for future screening programs. Finally we will shortly review new approaches that are used to study the molecular pathology of lung cancer and how they can be applied in a clinical setting.

Epidermal growth factor receptor expression status in lung cancer correlates with its mutation

The molecular mechanisms for frequent epidermal growth factor receptor (EGFR, a tyrosine kinase [TK]) and HER2 (the preferred coreceptor of EGFR) overexpression in lung cancer are poorly understood. Recent studies have shown the mutations of the TK domain in EGFR and HER2 to be present in lung cancer. The purpose of this study was to investigate the relationship between mutation status and expression of EGFR and HER2 in lung cancer. Immunostaining took place for EGFR and HER2, and mutational analyses for EGFR, HER2, and KRAS (a signaling protein) were conducted using 130 resected lung cancer specimens. Thirty-seven EGFR mutations (28%) and 8 HER2 mutations (6%), both of the TK domains, and 5 KRAS (4%) mutations were found, whereas 73 (56%) EGFR and 47 (36%) HER2 overexpressions were found. EGFR overexpression was seen more frequently in tumors with EGFR mutation (28/37, 76%) than in tumors without EGFR mutations (45/93, 48%; P = .0059). No correlation was found between HER2 mutation and HER2 expression. Multivariate regression revealed that EGFR mutation, adenocarcinoma histology, and HER2 expression were associated with EGFR expression, whereas female sex, EGFR mutation, and EGFR expression were associated with HER2 expression. In conclusion, EGFR and HER2 overexpression is frequent in lung cancer, and EGFR overexpression correlates with the EGFR TK domain mutations.

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.

Gastrin-releasing peptide receptor mediates activation of the epidermal growth factor receptor in lung cancer cells

Gastrin-releasing peptide receptor (GRPR) and the epidermal growth factor receptor (EGFR) are expressed in several cancers including non-small cell lung cancer (NSCLC). Here we demonstrate the activation of EGFR by the GRPR ligand, gastrin-releasing peptide (GRP), in NSCLC cells. GRP induced rapid activation of p44/42 MAPK in lung cancer cells through EGFR. GRP-mediated activation of MAPK in NSCLC cells was abrogated by pretreatment with the anti-EGFR-neutralizing antibody, C225. Pretreatment of NSCLC cells with neutralizing antibodies to the EGFR ligands, TGF-A or HB-EGF, also decreased GRP-mediated MAPK activation. On matrix metalloproteinase (MMP) inhibition, GRP failed to activate MAPK in NSCLC cells. EGF and GRP both stimulated NSCLC proliferation, and inhibition of either EGFR or GRPR resulted in cell death. Combining a GRPR antagonist with the EGFR tyrosine kinase inhibitor, gefitinib, resulted in additive cytotoxic effects. Additive effects were seen at gefitinib concentrations from 1 to 18 microM, encompassing the ID50 values of both gefitinib-sensitive and gefitinib-resistant NSCLC cell lines. Because a major effect of GRPR appears to be promoting the release of EGFR ligand, this study suggests that a greater inhibition of cell proliferation may occur by abrogating EGFR ligand release in consort with inhibition of EGFR.

Chemoprevention Strategies for Patients with Lung Cancer in the Context of Screening

Despite major advances in the treatment and management of lung cancer, most patients with lung cancer eventually die of this disease. Because conventional therapies have failed to make a major impact on survival, newer approaches are necessary in the battle against lung cancer. Better understanding of molecular biology of several tumors has led to novel targeted therapeutic approaches with potential utility in cancer treatment in general and lung cancer in particular. In addition to smoking cessation, targeting individuals at high risk by use of early detection or aiming at reversal of premalignant lesions seem like attractive strategies. In light of the noted improvement in molecular diagnostic tools and targeted therapies, the question of chemoprevention in the context of early detection deserves a closer look. In this article, we review what has been achieved in the area of chemoprevention and discuss possible prospects that may help reduce lung cancer mortality in the context of early detection.

Novel therapies in lung cancer

This article reviews novel therapies that are under development for non-small cell lung cancer and small cell lung cancer.

Protein overexpression and gene amplification of epidermal growth factor receptor in nonsmall cell lung carcinomas. An immunohistochemical and fluorescence in situ hybridization study

BACKGROUND

Recently, molecular therapies targeting epidermal growth factor receptor (EGFR) have been developed for clinical use. The current study was conducted to determine 1) the exact frequency of EGFR protein overexpression, 2) the correlation between protein overexpression and EGFR amplification, and 3) the correlation between the status of the genetic and clinicopathologic features in nonsmall cell lung carcinomas (NSCLC).

METHODS

In total, 181 NSCLC samples were examined immunohistochemically using an antibody against EGFR, and tumor cells that exhibited overexpression were examined further for EGFR amplification by fluorescence in situ hybridization.

RESULTS

Overexpression of EGFR protein was found in 34% of the tumors. Among these, EGFR amplification was demonstrated in 74%. High-level gene amplification was found exclusively in tumors cells with high protein expression. In most of these tumors, cells that exhibited EGFR overexpression and gene amplification were distributed heterogeneously, even within a single tumor nodule. Statistically, EGFR overexpression was correlated significantly with lymph node metastasis and with a more advanced pathologic stage. Moreover, in adenocarcinomas, gene amplification was correlated significantly with lymph node metastasis and tended to be correlated with a more advanced pathologic stage.

CONCLUSIONS

The overexpression of EGFR in NSCLC was accompanied predominantly, but not exclusively, by gene amplification. It is important to evaluate not only protein overexpression but also the EGFR status to design adjuvant therapies for patients with NSCLC, because specimens that exhibit both protein overexpression and gene amplification may predict eventual lymph node metastasis and, possibly, aggressive tumor behavior.

Three Emerging New Drugs for NSCLC: Pemetrexed, Bortezomib, and Cetuximab

Despite advances made in cytotoxic chemotherapy, the prognosis for patients with non-small cell lung cancer (NSCLC) continues to be poor. New, more effective drugs must be identified and developed to improve the outcome of these patients. Three drugs with promising activity in NSCLC are pemetrexed (Alimta; Eli Lilly and Company, Indianapolis, IN, http://www.lilly.com), bortezomib (Velcade; Millennium Pharmaceuticals, Inc., Cambridge, MA, http://www.mlnm.com), and cetuximab (Erbitux; ImClone Systems, Inc., New York, NY, http://www.imclone.com). Pemetrexed inhibits thymidylate synthase, dihydrofolate reductase, and glycinamide ribonucleotide formyl transferase, enzymes necessary for purine and pyrimidine synthesis, thus causing cell-cycle arrest in the S phase. Bortezomib, a proteasome inhibitor, interferes with the cytosolic protein degradation machinery, namely the ubiquitin-proteasome complex, causing breakdown of cell-cycle regulators and cell-cycle arrest. Cetuximab is a chimeric mouse-human antibody that inhibits ligand-dependent activation of the epidermal growth factor receptor, resulting in receptor internalization and inhibition of downstream pathways that, in turn, causes cell growth and progression. All three drugs are approved for different tumor types, and studies defining their role in NSCLC are under way.

Epidermal growth factor and hypoxia-induced expression of CXC chemokine receptor 4 on non-small cell lung cancer cells is regulated by the phosphatidylinositol 3-kinase/PTEN/AKT/mammalian target of rapamycin signaling pathway and activation of hypoxia inducible factor-1alpha

Non-small cell lung cancer (NSCLC) expresses a particularly aggressive metastatic phenotype, and patients with this disease have a poor prognosis. CXC chemokine receptor 4 (CXCR4) is a cell surface receptor that has been shown to mediate the metastasis of many solid tumors including lung, breast, kidney, and prostate. In addition, overexpression of the epidermal growth factor receptor (EGFR) is associated with the majority of NSCLC and has been implicated in the process of malignant transformation by promoting cell proliferation, cell survival, and motility. Here we show for the first time that activation of the EGFR by EGF increases CXCR4 expression and the migratory capacity of NSCLC cells. Furthermore, many solid tumors are associated with low oxygen tension, and when NSCLC cells were cultured with EGF under hypoxic conditions, CXCR4 expression was dramatically enhanced. A molecular analysis of these events indicated that augmented CXCR4 expression was regulated by the phosphatidylinositol 3-kinase/PTEN/AKT/mammalian target of rapamycin signal transduction pathway, activation of hypoxia inducible factor (HIF) 1alpha, and ultimately HIF-1-dependent transcription of the CXCR4 gene. Thus, a combination of low oxygen tension and overexpression of EGFR within the primary tumor of NSCLC may provide the microenvironmental signals necessary to upregulate CXCR4 expression and promote metastasis.

Epidermal growth factor receptor, HER-2/neu and related pathways in lung adenocarcinomas with bronchioloalveolar features

Lung adenocarcinomas with bronchioalveolar features (ABAF), formerly called bronchioloalveolar cancers (BAC), constitute a distinct clinical, radiological and pathological entity among lung malignancies. Epidermal growth factor receptor (EGFR) and to a less extent, HER-2/neu, are known to be overexpressed in non-small lung cancers, but their exact status in ABAF is not well-documented. Stimulation of these two receptors results in the initiation of two major cascades, namely phosphatidylinositol 3-kinase (PI-3K) and Ras-dependent pathways. We have therefore studied the expressions of EGFR, HER-2/neu as well as phosphorylated AKT (pAKT) and phosphorylated extracellular-signal regulated kinase (ERK), which are key molecules in these two pathways, in 15 ABAF patients. EGFR was found to be overexpressed in 9 of 15 patients (60%). HER-2/neu overexpression was detected in 6 of the 14 tumors tested (43%). pAKT and pERK were both found to be positive in 13 of 15 patients (87%). Six of the seven tumors with mucinous pattern were negative for EGFR, while all of the other eight cases were positive (P=0.001). Mucinous tumors were also less likely than non-mucinous tumors to overexpress HER-2/neu (17% versus 63%, respectively). These findings suggest that ABAF, particularly those with non-mucinous histology, commonly harbors EGFR and HER-2/neu overexpression. PI-3K and Ras-dependant pathways that lie downstream are generally activated, even in the absence of EGFR and/or HER-2/neu overexpression. ABAF may be a particularly promising candidate for EGFR-targeted strategies and this possibility merits extensive evaluation in clinical trials.

ERCC1 Expression Is a Predictor of Survival in Resected Patients With Non-small Cell Lung Cancer

STUDY OBJECTIVES

Proteins of the nucleotide excision repair pathway repair DNA damage. The excision repair cross-complementing (ERCC) gene family reduces damage to DNA by nucleotide excision and repair. Impaired nuclear excision repair could lead to increased genomic instability that in turn could lead to a more malignant phenotypic behavior of tumors. We therefore evaluated the effect of intratumoral ERCC1 expression on survival in non-small cell lung cancer (NSCLC) patients who underwent surgical resection for cure.

DESIGN

Resected tumor and the corresponding normal lung specimens from 51 patients with NSCLC who underwent surgical resection were immediately frozen in liquid nitrogen. Total RNA was extracted, reverse transcribed, and amplified with intron-spanning primers. Quantitation for ERCC1 was done using the Taqman procedure, and gene expression was normalized using 18SrRNA expression as internal reference with ERCC1 levels expressed a unit-less ratio.

RESULTS

Tumoral ERCC1 expression ranged from 4.96 to 2,008, with a median value of 54.76. Using an ERCC1 value of 50 to dichotomize the cohort, there was a statistically significant difference in median survival for patients with ERCC1 expression > 50 (94.6 months) compared to < 50 (35.5 months) [p = 0.01]. Multivariate analysis revealed that high ERCC1 expression independently predicted for longer survival. There were no significant correlations between ERCC1 expression in tumor tissue and normal lung.

CONCLUSIONS

We conclude that resected NSCLC patients with high ERCC1 expression (> 50) have a better survival when compared to patients with low ERCC1 expression (< 50). We postulate that an intact DNA repair mechanism may reduce the accumulation of genetic aberrations that are thought to contribute to a tumors malignant potential and therefore the risk of relapse after definitive treatment. Future adjuvant and neoadjuvant chemotherapy trials in NSCLC could stratify patients according to their ERCC1 expression levels.

Biomarkers in non-small cell lung cancer prevention

Identification of biomarkers is one of the most promising approaches for the detection of early malignant or even premalignant lesions with the chance of diagnosing early stages of non-small cell lung cancer that could be treated curatively. Alterations of chromosomes (3p, 5q, 9p), genes (Rb, C-myc, C-mos, hTERT), proteins (p16, p53, K-ras, hnRNP A2/B1, MCM2, EGFR, erbB-2, erbB-3, erbB-4) and others can be found in lung cancer. Some of these occur at early stages of the disease and few could serve as potential screening markers. The actual literature is reviewed and the relevance of the different biomarkers for early lung cancer detection is discussed.

The Effects of Cetuximab Alone and in Combination With Radiation and/or Chemotherapy in Lung Cancer

Purpose: The epidermal growth factor receptor (EGFR) overexpressed in approximately 80% of non-small cell lung cancers (NSCLC) is a target for novel therapeutics. Concurrent chemoradiation is the current standard of care for treatment of patients with locally advanced NSCLC. However, &lt; 20% of patients remain disease-free at 5 years despite this aggressive treatment. Cetuximab is a humanized monoclonal antibody that recognizes the human EGFR, and in previous studies, inhibited the growth of EGFR-expressing human cancer cell lines. In this report, we investigated the cellular and molecular effects of cetuximab alone and in combination with radiation and/or chemotherapy in human NSCLC cell lines with varying levels of EGFR overexpression in vitro and in vivo.

Experimental Design: We evaluated the EGFR status of a panel of human NSCLC cancer cell lines by immunohistochemistry and flow cytometry. We then evaluated cetuximab effects on growth, cell cycle distribution, and downstream intracellular signaling molecules in this panel of NSCLC cancer cell lines. NSCLC cell lines were treated with cetuximab alone or in combination with radiation, chemotherapy, or chemoradiation to determine the cooperative effects of cetuximab both in vitro and in vivo in athymic nude mice bearing NSCLC xenografts.

Results: Cetuximab alone inhibited the in vitro growth of some but not all EGFR-expressing NSCLC cell lines in a dose-dependent manner. Flow cytometric analysis of cell cycle distribution after 24 hours of cetuximab treatment revealed a shift into the G0/G1 phase of the cell cycle in cetuximab-sensitive EGFR-expressing cell lines and at concentrations that were growth-inhibitory. There were no cell cycle changes in the EGFR-negative cell lines. After 4 hours of exposure, cetuximab reduced epidermal growth factor (EGF)-induced phosphorylation of EGFR (pEGFR) and HER-2 (pHER2) in cetuximab-sensitive cell lines but not in cetuximab-resistant cell lines. Cetuximab reduced EGF-induced phosphorylation of extracellular signal-regulated kinase-1/2 (pERK) in all EGFR-expressing cell lines. In the absence of EGF, cetuximab alone increased the level of pEGFR and pHER2 above that seen in untreated control cells in both sensitive and resistant cell lines that were EGFR- and HER2-positive, but not in EGFR- or HER2-negative lines. Despite the cetuximab-induced increase in phosphorylation of EGFR and HER2, peak EGF-induced levels of pEGFR and pHER2 were reduced by cetuximab in the cetuximab-sensitive lines but not in the resistant lines. Cooperative (combination index values &lt; 1.0) growth inhibitory effects were observed in vitro combination assays with cetuximab and radiation only in cetuximab-sensitive NSCLC cell lines. A lack of cooperation was seen in cetuximab-insensitive NSCLC cell lines. Similar findings were observed with in vitro combination studies of cetuximab plus cisplatin or paclitaxel. In nude mice bearing EGFR-expressing, cetuximab-sensitive, NSCLC cell line xenografts, cetuximab plus radiation induced a marked improvement in tumor growth inhibition over either agent alone. The growth inhibitory effects of cetuximab-radiation were similar to the growth inhibitory effects of concurrent chemoradiation. Triple combination therapy of cetuximab and chemoradiation yielded a nonsignificant advantage in tumor growth control over doublet combinations (cetuximab and radiation or chemoradiation) in vivo.

Conclusions: Similar results in tumor growth inhibition observed in mice treated with cetuximab-radiation and cisplatin-radiation provide a rationale for the clinical investigation of cetuximab with concurrent radiation in selected patients with locally advanced NSCLC. Local tumor control and treatment toxicity should be evaluated between cetuximab-radiation and chemoradiation regimens. Proper patient selection will be critical to the success of such trials and further studies are needed to identify optimal patient selection criteria.

Life and death decisions: ceramide generation and EGF receptor trafficking are modulated by oxidative stress

Reactive oxidants are associated with the pathogenesis of pulmonary diseases and affect various cell functions, from proliferation to apoptosis. We have shown that oxidants exert growth control on airway epithelial cells by modulating upstream receptor function. Additionally, hydrogen peroxide-mediated oxidative stress modulates ceramide levels to induce apoptosis in lung epithelium. Depletion of glutathione in lung epithelial cells results in ceramide accumulation, suggesting that ceramide elevation, coupled to oxidative stress, initiates apoptosis. While it is desirable to prevent cell death and tissue injury induced by oxidants in diseases such as asthma or acute respiratory distress syndrome, the opposite is sought in cancer. But oxidants may also activate growth factor receptors, enhancing cell proliferation and facilitating tumor promotion. Under oxidative stress, phosphorylation of the epidermal growth factor receptor (EGFR) is abrogated at tyrosine 1,045, the docking site for the ubiquitin ligase c-Cbl, rendering EGFR unable to recruit c-Cbl and be ubiquitylated and degraded. We thus proposed that this deficiency, which confers prolonged receptor signaling at the plasma membrane, links oxidative stress, EGFR, and tumorigenesis. Decoding the molecular interactions between oxidative stress and ceramide pathways and characterizing ubiquitylation control of receptor desensitization should provide new strategies for intervention in diverse pulmonary diseases and in diagnosing and eradicating cancer.

Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor Does Not Improve Paclitaxel Effect in an Orthotopic Mouse Model of Lung Cancer

PURPOSE

The purpose is to evaluate whether inhibition of epidermal growth factor receptor (EGFR) activation by PKI166, an EGFR-tyrosine kinase inhibitor, affects growth of human lung cancer implanted orthotopically into the lungs of nude mice.

EXPERIMENTAL DESIGN

Lungs of mice were injected with NCI-H358 human bronchioloalveolar cancer cells. In three experiments, groups of mice (n = 10 per group) were randomized 7 days after tumor implantation to receive one of the following treatments: i.p. paclitaxel 100 or 200 microg (4 or 8 mg/kg) once per week, oral PKI166 100 or 200 mg/kg three times per week, paclitaxel plus PKI166, or i.p. saline and oral PKI166-vehicle (control) for 5 weeks. Mice were killed 6.5 to 8 weeks after tumor implantation. The experiments were repeated with PC14PE6 human lung adenocarcinoma cells to assess effect on survival.

RESULTS

Immunohistochemical analyses revealed the expression and phosphorylation of EGFR in the growing tumors. Treatment with PKI166 alone or in combination with paclitaxel diminished activation of EGFR on tumor cells, yet maximal therapeutic effect was observed in mice treated with paclitaxel alone. Activated mitogen-activated protein kinase and basic fibroblast growth factor expression were similar in all treatment groups. Survival in mice treated with the combination of paclitaxel and PKI166 was shorter than in those treated with paclitaxel alone.

CONCLUSIONS

Our results suggest that concurrent administration of EGFR-tyrosine kinase inhibitor and chemotherapy is equivalent and may indeed be inferior to chemotherapy alone, even if EGFR is functional and its phosphorylation effectively inhibited. Our data show that the interaction of EGFR-TKIs and chemotherapy is complex and suggest that other growth factors may activate the downstream signaling events.

Metal-induced oxidative stress and signal transduction

Occupational and environmental exposures to metals are associated with the development of various cancers. Although carcinogenesis caused by metals has been intensively investigated, the mechanisms of action, especially at the molecular level, are still unclear. Accumulating evidence indicates that reactive oxygen species generated by metals may play an important role in the etiology of disease. This review covers recent advances in (1) metal-induced generation of reactive oxygen species; (2) the receptors, kinases, and nuclear transcription factors affected by metals and metal-induced oxidative stress, including growth factor receptors, src kinase, ras signaling, mitogen-activated protein kinases, the phosphoinositide 3-phosphate/Akt pathway, nuclear transcription factor kappaB, activator protein 1, p53, nuclear factor of activated T cells, and hypoxia-inducible factor 1; and (3) global cellular phenomena (signal transduction, cell cycle regulation, and apoptosis) associated with metal-induced ROS production and gene expression.

Mechanisms and effectors of MIF-dependent promotion of tumourigenesis

The importance of secreted cytokines and growth factors in the development and promotion of malignancies is often underestimated. Many different soluble, extracellular gene products participate in processes that collectively contribute to the growth and survival of a developing neoplasm. These secreted molecules can, directly or indirectly, play a central role in uncontrolled tumour cell division, angiogenic stimulation or suppression of tumour cell immune surveillance. One of the first cytokine activities ever described, macrophage migration inhibitory factor (MIF), is unique to these soluble mediators in that it participates in all of these pro-tumourigenic processes. Overexpressed in most tumour types examined, MIF has been shown to promote malignant cell transformation, inhibit tumour cell-specific immune cytolytic responses and strongly enhance neovascularization. Despite this broad array of activities, the elucidation of molecular and cellular mechanisms involved in MIF-dependent bioactions has remained elusive. This review will focus on recently characterized phenotypes and mechanistic effectors thought to be associated with MIF-dependent promotion of neoplastic processes and discuss their relative importance in carcinogenesis.

Recent advances in management of small-cell lung cancer

Small-cell lung cancer (SCLC) is a smoking-related disease with a poor prognosis. While SCLC is usually initially sensitive to chemotherapy and radiotherapy, responses are rarely long lasting. Frustratingly, most patients ultimately relapse, often with increasingly treatment resistant disease. Many strategies have been developed in an attempt to improve treatment outcomes, which have plateaued since the introduction of combination chemotherapy in the 1980s. These include trials of maintenance therapy, and dose intensification, the latter by means of increasing dose density, growth factor support and high dose chemotherapy with autologous stem cell rescue. None have been shown to improve patient survival. On the other hand, the integration of concurrent thoracic radiation and prophylactic cranial irradiation has improved the survival outcomes in patients with limited disease. In extensive disease, irinotecan combined with cisplatin has shown promise in improving survival over conventional platinum/etoposide chemotherapy schedules and a confirmatory study is awaited. The future of SCLC treatment may however lie with molecularly targeted therapies, such as antiangiogenesis agents and signal transduction inhibitors, which are being studied at present.

Risk factors for interstitial lung disease and predictive factors for tumor response in patients with advanced non-small cell lung cancer treated with gefitinib

A high incidence of interstitial lung disease (ILD) has been reported in patients with non-small cell lung cancer (NSCLC) treated with gefitinib in Japan. We retrospectively analyzed 112 patients with advanced NSCLC who received gefitinib monotherapy. Univariate and multivariate analyses were used to identify risk factors for gefitinib-related ILD and predictive factors for tumor response to gefitinib. The incidence of ILD was 5.4%, and it was higher in the patients with pre-existing pulmonary fibrosis (33% versus 2%; P < 0.001). The results of a multivariate analysis showed that pulmonary fibrosis was a significant risk factor for ILD (odds ratio: 177, 95% confidence interval: 4.53-6927, P = 0.006). The response rate was 33% in the 98 evaluable patients and higher in women (53% versus 23%; P = 0.003), patients with adenocarcinoma (38% versus 6%; P = 0.010), never-smokers (63% versus 18%; P < 0.001), and the patients with no history of thoracic radiotherapy (39% versus 13%; P = 0.015). The results of a multivariate analysis showed that the predictors of tumor response were "no history of smoking" and "no history of thoracic radiotherapy". Never-smokers had a significantly longer survival time than smokers (P = 0.007). Although gefitinib therapy confers a clinical benefit on patients with advanced NSCLC, especially on women, patients with adenocarcinoma, never-smokers, and patients with no history of thoracic radiotherapy, it also poses a high risk of ILD, especially to patients with pulmonary fibrosis. The risk-benefit ratio must be carefully considered.

Signaling through the epidermal growth factor receptor during the development of malignancy

The epidermal growth factor receptor (EGFR) is overexpressed and/or constitutively activated in a variety of human malignancies. Detection of increased expression levels of EGFR in cancer and the association between overexpression and decreased patient survival has led to the development of several therapeutic strategies to target this receptor. The results of early-phase clinical trials to date suggest that targeting EGFR alone may not be sufficient to eradicate established tumors. This limited antitumor efficacy as monotherapy has led to combining EGFR inhibitors with chemotherapy or radiation therapy for advanced disease, or incorporating EGFR inhibition to cancer prevention approaches. This review will discuss the role of EGFR signaling in carcinogenesis and the rationale for EGFR inhibition as a clinical prevention and treatment strategy.

Analysis of epidermal growth factor receptor expression as a predictive factor for response to gefitinib ('Iressa', ZD1839) in non-small-cell lung cancer

Gefitinib ('Iressa', ZD1839) is an orally active epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that has demonstrated antitumour activity and favourable tolerability in Phase II studies. We investigated whether EGFR expression levels could predict for response to gefitinib in patients with advanced non-small-cell lung cancer (NSCLC), who received gefitinib (250 mg day(-1)) as part of a worldwide compassionate-use programme. Tissue samples were analysed by immunohistochemistry to assess membrane EGFR immunoreactivity. Of 147 patients enrolled in our institution, 50 patients were evaluable for assessment of both clinical response and EGFR expression. The objective tumour response rate was 10% and disease control was achieved in 50% of patients. Although high EGFR expression was more common in squamous-cell carcinomas than adenocarcinomas, all objective responses were observed in patients with adenocarcinoma. Response and disease control with gefitinib were not associated with high EGFR expression. Overall, median survival was 4 months, and the 1-year survival rate was 18%. Strong EGFR staining correlated with shorter survival time for all patients. Gefitinib demonstrated promising clinical activity in this group of patients with NSCLC. These results have also shown that EGFR expression is not a significant predictive factor for response to gefitinib.