Quantitative determination of nuclear and cytoplasmic epidermal growth factor receptor expression in oropharyngeal squamous cell cancer by using automated quantitative analysis

Nuclear translocation of the epidermal growth factor receptor family membrane tyrosine kinase receptors

Integral membrane proteins contain a hydrophobic transmembrane domain and mainly locate in the plasma membrane lipid bilayer. The receptor tyrosine kinases (RTK) of the epidermal growth factor receptor (EGFR) superfamily, including ErbB-1, ErbB-2, ErbB-3, and ErbB-4, constitute an important group of such membrane proteins, which have a profound impact on cancer initiation, progression, and patient outcome. Although studies of their functions have conventionally focused on their membrane-associated forms, documented observations of the presence of these membrane receptors and their functioning partners in the nucleus have reshaped the intracellular geography and highlight the need to modify the central dogma. The ErbB proteins in the membrane can translocate to the nucleus through different mechanisms. Nuclear RTKs regulate a variety of cellular functions, such as cell proliferation, DNA damage repair, and signal transduction, both in normal tissues and in human cancer cell. In addition, they play important roles in determining cancer response to cancer therapy. Nuclear presence of these ErbB proteins is emerging as an important marker in human cancers. An integrated picture of the RTK-centered signaling transduction network extending from the membrane-cytoplasm boundary to the nuclear compartment is looming in the foreseeable horizon for clinical application.

Ultraviolet irradiation-induces epidermal growth factor receptor (EGFR) nuclear translocation in human keratinocytes

Epidermal growth factor receptor (EGFR) plays a critical role in mediating ultraviolet (UV) irradiation-induced signal transduction and gene expression in human keratinocytes. EGFR activation results from increased phosphorylation on specific tyrosine residues in the C-terminal intracellular domain. It has recently been reported that following growth factor stimulation EGFR translocates from the surface membrane to the nucleus, where it may directly regulate gene transcription. We have investigated the ability of UV irradiation to induce EGFR nuclear translocation in human primary and HaCaT keratinocytes. UV irradiation caused rapid nuclear translocation of EGFR. Significant accumulation of EGFR in the nucleus was observed within 15 min after UV irradiation exposure. Maximal translocation occurred at 30 min post-UV irradiation, and resulted in a 10-fold increase in EGFR in the nucleus, as determined by Western blot analysis of nuclear extracts and confirmed by immunofluorescence. Inhibition of nuclear export by Leptomycin B did not alter UV irradiation-induced nuclear accumulation. EGFR tyrosine kinase inhibitor (PD169540) reduced UV irradiation-induced EGFR nuclear translocation 50%. Mutation of either tyrosine 1148 or tyrosine 1173 reduced nuclear translocation 70%, while mutation of tyrosine 1068 was without effect. In addition, over-expression of receptor type protein tyrosine phosphatase-kappa (RPTP-kappa), which specifically dephosphorylates EGFR tyrosines, decreased UV irradiation-induced EGFR nuclear translocation in human keratinocytes. These data demonstrate that UV irradiation stimulates rapid EGFR nuclear translocation, which is dependent on phosphorylation of specific EGFR tyrosine residues. EGFR nuclear translocation may act in concert with conventional signaling pathways to mediate UV irradiation-induced responses in human keratinocytes.

Nuclear EGFR contributes to acquired resistance to cetuximab

Epidermal growth factor receptor (EGFR) is a ubiquitously expressed receptor tyrosine kinase involved in the etiology of several human cancers. Cetuximab is an EGFR-blocking antibody that has been approved for the treatment of patients with head and neck squamous cell carcinoma and metastatic colorectal cancer. Previous reports have shown that EGFR translocation to the nucleus is associated with cell proliferation. Here we investigated mechanisms of acquired resistance to cetuximab using a model derived from the non-small cell lung cancer line H226. We demonstrated that cetuximab-resistant cells overexpress HER family ligands including epidermal growth factor (EGF), amphiregulin, heparin-binding EGF and beta-cellulin. Overexpression of these ligands is associated with the nuclear translocation of the EGFR and this process was mediated by the Src family kinases (SFK). Treatment of cetuximab-resistant cells with the SFK inhibitor, dasatinib, resulted in loss of nuclear EGFR, increased membrane expression of the EGFR and resensitization to cetuximab. In addition, expression of a nuclear localization sequence-tagged EGFR in cetuximab-sensitive cells increased resistance to cetuximab both in vitro and in mouse xenografts. Collectively, these data suggest that nuclear expression of EGFR may be an important molecular determinant of resistance to cetuximab therapy and provides a rationale for investigating nuclear EGFR as a biomarker for cetuximab response. Further, these data suggest a rationale for the design of clinical trials that examine the value of treating patients with cetuximab-resistant tumors with inhibitors of SFKs in combination with cetuximab.

Validation of lysyl oxidase as a prognostic marker for metastasis and survival in head and neck squamous cell carcinoma: Radiation Therapy Oncology Group trial 90-03

PURPOSE

To validate lysyl oxidase (LOX), a hypoxia-related protein, as a marker for metastasis in an independent head and neck cancer (HNC) patient group enrolled onto a prospective trial.

PATIENTS AND METHODS

We performed traditional immunohistochemical (IHC) staining and automated quantitative analysis (AQUA) for LOX expression in 66 HNC patients from one institution. We also performed AQUA staining for LOX in 306 of 1,113 patients treated on a phase III trial comparing four radiation fractionation schedules in locally advanced HNC (RTOG 90-03). Pretreatment characteristics and outcome were similar between patients with and without LOX assessment. We correlated AQUA LOX expression with time to metastasis (TTM), time to progression (TTP), and overall survival (OS).

RESULTS

LOX expression from both staining methods predicted for TTM in the first 66 patients. Multivariate analysis, controlling for significant parameters including nodal stage and performance status, revealed tumor LOX expression, as a continuous variable, was an independent predictor for TTM (hazard ratio [HR], 1.21; 95% CI, 1.10 to 1.33; P = .0001), TTP (HR, 1.06; 95% CI, 1.02 to 1.10; P = .0069), and OS (HR, 1.04; 95% CI, 1.00 to 1.07; P = .0311) in RTOG 90-03 patients. This translates into a 259% increase in metastatic risk for a patient at the 75th percentile of LOX compared with one at the 25th percentile.

CONCLUSION

AQUA LOX expression was strongly associated with increased metastasis, progression, and death in RTOG 90-03 patients. This study validates that LOX is a marker for metastasis and survival in HNC.

Targeting EGFR resistance networks in head and neck cancer

A core set of oncoproteins is overexpressed or functionally activated in many types of cancer, and members of this group have attracted significant interest as subjects for development of targeted therapeutics. For some oncoproteins such as EGFR/ErbB1, both small molecule and antibody agents have been developed and applied in the clinic for over a decade. Analysis of clinical outcomes has revealed an initially unexpected complexity in the response of patients to these agents. Diverse factors, including developmental lineage of the tumor progenitor cell, co-mutation or epigenetic modulation of genes encoding proteins in an extended EGFR signaling network or regulating core survival responses in individual tumors, and environmental factors including inflammatory agents and viral infection, all have been identified as modulating response to treatment with EGFR-targeted drugs. Second and third generation therapeutic strategies increasingly incorporate knowledge of cancer type-specific signaling environments, in a more personalized treatment approach. This review takes squamous cell carcinoma of the head and neck (SCCHN) as a specific example of an EGFR-involved cancer with idiosyncratic biological features that influence design of treatment modalities, with particular emphasis on commonalities and differences with other cancer types.

Nuclear expression of epidermal growth factor receptor is a novel prognostic value in patients with ovarian cancer

The epidermal growth factor receptor (EGFR) has previously been detected in the nucleus of cancer cells and primary tumors. We have reported that EGFR translocates from the plasma membrane to the nucleus. Accumulation of nuclear EGFR is linked to increased DNA synthesis and proliferation; however, the pathological significance of nuclear EGFR is not completely understood. Here, we sought to determine the predictive value of EGFR for the survival of ovarian cancer patients, through the examination of 221 cases of ovarian cancer tissues by immunohistochemical analysis to determine nuclear EGFR expression. In addition, we also examined cyclin D1 and Ki-67 through immunohistochemisty. Furthermore, we examined nuclear EGFR levels in ovarian cancer cell lines treated with EGF, and primary ovarian tumor tissue using immunofluorescence analysis. Nuclear fractions extracted from serum-starved cells treated with or without EGF were subjected to SDS-PAGE and Western blot analyses. We found that 28.3% of the cohort had high levels of nuclear EGFR, while 22.5% had low levels of nuclear EGFR, and 49.2% were negative for nuclear EGFR. Importantly, there was an inverse correlation between high nuclear EGFR, cyclin D1, and Ki-67 with overall survival (P < 0.01, P < 0.09, P < 0.041). Additionally, nuclear EGFR correlated positively with increased levels of cyclin D1 and Ki-67, both indicators for cell proliferation. Our findings indicate a pathological significance of nuclear EGFR that might be important for predicting clinical prognosis of ovarian cancer patients.

Molecular pathology of head and neck cancer: implications for diagnosis, prognosis, and treatment

The prototypic head and neck squamous cell carcinoma (HNSCC) arises from the mucosal lining of the upper aerodigestive tract, demonstrates squamous differentiation microscopically, involves older men with a long history of cigarette smoking and alcohol consumption, and is treated by multimodality therapy. HNSCC has long been regarded as a uniform disease process requiring a methodical and unwavering therapeutic approach. Divergence in epidemiologic trends among HNSCCs arising from different anatomic sites has introduced a view that, morphologic repetition aside, head and neck cancers form a heterogeneous group. This view has been supported at the molecular genetic level. A more complete understanding of the molecular genetics of head and neck cancer is providing new insights into long-held but poorly comprehended concepts such as field cancerization and is introducing various biomarkers with potential application for diagnosing, staging, monitoring, and prognosticating HNSCC.

PET monitoring of therapy response in head and neck squamous cell carcinoma

In the Western world, more than 90% of head and neck cancers are head and neck squamous cell carcinomas (HNSCCs). The most appropriate treatment approach for HNSCC varies with the disease stage and disease site in the head and neck. Concurrent chemoradiotherapy has become a widely used means for the definitive treatment of locoregionally advanced HNSCC. Although this multimodality treatment provides higher response rates than radiotherapy alone, the detection of residual viable tumor after the end of therapy remains an important issue and is one of the major applications of (18)F-FDG PET. Studies have shown that negative (18)F-FDG PET or PET/CT results after concurrent chemoradiotherapy have a high negative predictive value (>95%), whereas the positive predictive value is only about 50%. However, when applied properly, FDG PET/CT can exclude residual disease in most patients, particularly patients with residual enlarged lymph nodes who would otherwise undergo neck dissection. In contrast to other malignancies, data are limited on the utility of (18)F-FDG PET for monitoring the response to induction chemotherapy in HNSCC or for assessing treatment response early during the course of definitive chemoradiotherapy. The proliferation marker (18)F-3'-deoxy-3'fluorothymidine is currently under study for this purpose. Beyond standard chemotherapy, newer treatment regimens in HNSCC take advantage of our improved understanding of tumor biology. Two molecules important in the progression of HNSCC are the epidermal growth factor receptor and the vascular endothelial growth factor (VEGF) and its receptor VEGF-R. Drugs attacking these molecules are now under study for HNSCC. PET probes have been developed for imaging the presence of these molecules in HNSCC and their inhibition by specific drug interaction; the relevance of these probes for response assessment in HNSCC will be discussed. Hypoxia is a common phenomenon in HNSCC and renders cancers resistant to chemo- and radiotherapy. Imaging and quantification of hypoxia with PET probes is under study and may become a prerequisite for overcoming chemo- and radioresistance using radiosensitizing drugs or hypoxia-directed irradiation techniques and for monitoring the response to these techniques in selected groups of patients. Although (18)F-FDG PET/CT will remain the major clinical tool for monitoring treatment in HNSCC, other PET probes may have a role in identifying patients who are likely to benefit from treatment strategies that include biologic agents such as epidermal growth factor receptor inhibitors or VEGF inhibitors.

Protein expression of matriptase and its cognate inhibitor HAI-1 in human prostate cancer: a tissue microarray and automated quantitative analysis

Recent studies have suggested that matriptase, a transmembrane serine protease and its cognate inhibitor hepatocyte growth factor activator inhibitor-1 (HAI-1) are important in the progression of many cancers. Limited quantitative data are available on these proteins in prostate cancer. To validate the roles of matriptase and HAI-1 in prostate cancer and its progression, a prostate cancer tissue microarray was constructed. The tissue microarray includes 41 localized prostate cancers (Pca_local), 18 aggressive prostate cancers, 18 metastatic prostate cancers, 24 benign prostate hyperplasias, 18 high-grade intraepithelial neoplasias (HGPIN), and 41 benign prostate tissues. The cellular expression levels of matriptase and HAI-1 were quantified using automated quantitative analysis. We found that matriptase expression levels were significantly higher in Pca_local (P<0.0001) and HGPIN (P<0.05) compared with benign prostate tissue. Matriptase levels were significantly decreased in metastatic cancer when compared with all other tissue types (P<0.05). Compared with benign prostate tissue, HAI-1 expression levels were significantly higher in all proliferative prostate diseases (benign prostate hyperplasia, HGPIN, localized and aggressive cancers, and metastases) (P<0.001); yet, no significant differences were found in HAI-1 expression levels among the diseased tissue types. These results suggest that an increase of matriptase may be useful as a marker for detection of Pca_local, whereas a decrease of matriptase expression may signal prostate cancer progression. HAI-1 seems to be a marker of prostate epithelial cell proliferation.

EGFR inhibition as a therapy for head and neck squamous cell carcinoma

BACKGROUND

Improved understanding of disease biology of head and neck squamous cell carcinoma (HNSCC) with nearly universal expression of EGFR has led to the introduction of targeted therapies to interrupt signalling of this negative prognostic marker.

OBJECTIVE

We performed a literature review on the mechanisms and efficacy of anti-EGFR antibodies and EGFR tyrosine kinase inhibitors in patients with locally advanced or recurrent/metastatic HNSCC.

RESULTS/CONCLUSION

Clinical trials in HNSCC have administered EGFR directed drugs as single agents, in combination with chemotherapy or radiotherapy and demonstrated a good safety profile with antitumour activity in a subgroup of patients. The biology of responsiveness is still unclear, although there is growing evidence of an association of skin toxicity or presence of shorter EGFR intron 1 cytosine-adenine repeats with positive outcome.

Emerging perspectives in epidermal growth factor receptor targeting in head and neck cancer

The epidermal growth factor receptor (EGFR) has been shown to be a promising therapeutic target in head and neck cancer. Cetuximab, a monoclonal antibody against EGFR, has been approved in the United States for use with radiotherapy for head and neck squamous cell carcinoma. However, the role of EGFR targeting agents in other therapeutic modalities, such as combined chemoradiotherapy or induction chemotherapy, remains to be defined. Although results from several clinical trials have demonstrated the therapeutic potentials of EGFR targeting agents in these settings, further studies are necessary before definitive conclusions can be made. The concurrent targeting of EGFR along with other pathways important in carcinogenesis may hold significant therapeutic potential. In particular, several clinical trials are studying the effects of combining agents that target the vascular endothelial growth factor with EGFR inhibitors. Last, studies are ongoing to elucidate the predictive and correlative biomarkers in anti-EGFR therapy to allow for proper patient selection. In the case of cetuximab, these correlative biomarkers may include elements of the immune system in addition to the signal transduction proteins involved in EGFR pathway.

No detectable hypoxia in malignant salivary gland tumors: preliminary results

PURPOSE

Hypoxia is detected in most solid tumors and is associated with malignant progression and adverse treatment outcomes. However, the oxygenation status of malignant salivary gland tumors has not been previously studied. The aim of this study was to investigate the potential clinical relevance of hypoxia in this tumor type.

METHODS AND MATERIALS

Twelve patients scheduled for surgical resection of a salivary gland tumor were preoperatively injected with the hypoxia marker pimonidazole and the proliferation marker iododeoxyuridine. Tissue samples of the dissected tumor were immunohistochemically stained for blood vessels, pimonidazole, carbonic anhydrase-IX, glucose transporters-1 and -3 (Glut-1, Glut-3), hypoxia-inducible factor-1alpha, iododeoxyuridine, and epidermal growth factor receptor. The tissue sections were quantitatively assessed by computerized image analysis.

RESULTS

The tissue material from 8 patients was of sufficient quality for quantitative analysis. All tumors were negative for pimonidazole binding, as well as for carbonic anhydrase-IX, Glut-1, Glut-3, and hypoxia-inducible factor-1alpha. The vascular density was high, with a median value of 285 mm(-2) (range, 209-546). The iododeoxyuridine-labeling index varied from <0.1% to 12.2% (median, 2.2%). Epidermal growth factor receptor expression levels were mostly moderate to high. In one-half of the cases, nuclear expression of epidermal growth factor receptor was observed.

CONCLUSION

The absence of detectable pimonidazole binding, as well as the lack of expression of hypoxia-associated proteins in all tumors, indicates that malignant salivary gland tumors are generally well oxygenated. It is unlikely that hypoxia is a relevant factor for their clinical behavior and treatment responsiveness.

Correlates and determinants of nuclear epidermal growth factor receptor content in an oropharyngeal cancer tissue microarray

BACKGROUND

We have previously reported nuclear localization of epidermal growth factor receptor (EGFR) protein in oropharyngeal cancer tissue. Nuclear EGFR levels were inversely correlated with survival and response to radiotherapy. Here, we sought to identify the determinants and correlates of nuclear EGFR content.

METHODS

We analyzed an oropharyngeal cancer tissue microarray for the expression of the key molecules of the EGFR signaling cascade using an automated image analysis technique (AQUA) scored on a scale of 0 to 255, which permits protein quantitation and subcellular localization. Patients with oropharyngeal squamous cell cancer treated with radiotherapy or surgery and radiotherapy were eligible. Data were analyzed using Spearman correlations and multiple linear regression with robust SEs.

RESULTS

Of the 95 tumors included in this study, 72 (75%) had sufficient tissue for analysis of nuclear EGFR. Nuclear EGFR levels were associated with membranous/cytoplasmic EGFR levels (rho = 0.82, P < 0.001), nuclear extracellular signal-regulated kinase-2 (rho = 0.30, P = 0.01), and nuclear proliferating cell nuclear antigen (PCNA; rho = 0.36, P = 0.003). Nuclear phosphorylated-Akt, cyclin D1, phosphatase and tensin homolog (mutated in multiple cancers 1) (PTEN), p53, and proliferation marker Ki-67 levels did not correlate with nuclear EGFR level. In multivariable analysis, only PCNA retained its significant association (P = 0.01).

CONCLUSIONS

These results are consistent with preclinical data showing that EGFR may function as a tyrosine kinase in the nucleus, phosphorylating and stabilizing PCNA. The nuclear activity of EGFR may constitute a novel therapeutic target.

Microvessel area using automated image analysis is reproducible and is associated with prognosis in breast cancer

Microvessel density may be one measure of tumor associated angiogenesis but is methodologically difficult to standardize and reproduce. We used our automated quantitative image analysis system, AQUA, to more objectively assess microvessel area. Cytokeratin and CD31 were used to create tumor and vessel compartments respectively with AQUA. Microvessel area was defined as CD31 compartment area normalized to the tissue spot area (CD31 area/area of entire tissue spot). Consecutive breast cancer whole sections were stained with CD31 to compare pathologist-based microvessel density with AQUA microvessel area. Microvessel areas of 3-fold redundant tissue microarrays of 652 primary breast cancers were also assessed. CD34 and factor VIII-related antigen were also tested. There was nearly linear correlation between pathologist's microvessel density and AQUA microvessel area with regression coefficient R = 0.846. On the redundant arrays, of the 67% evaluable cases, 52% were microvessel area high and 48% low with good reproducibility of scores (Spearman rho 0.551). AQUA microvessel area was associated with larger tumors, node positivity, and estrogen receptor negativity, with 20 year survival at the univariate and multivariate levels (P < .0001 and P = .0121, respectively). CD34 or factor VIII-related antigen were more heterogenous, had poor association with CD31, and did not correlate with outcome. AQUA-based microvessel area was significantly correlated with both standard breast cancer prognostic parameters as well as with clinical outcome. In the future, it may also allow the use of the AQUA-based algorithms to quantify the expression of angiogenic biomarkers to either tumor or microvessel area-specific compartments.

Biomarker validation: in situ analysis of protein expression using semiquantitative immunohistochemistry-based techniques

Biomarker-driven cancer research is common in the current literature. Much of this research is a result of the increase in genomic and proteomic high-throughput technologies, which have increased our knowledge and also produced an abundance of data with unclear clinical significance. Immunohistochemistry-based assessment of protein expression is a natural validation method of expression-profiling data that is easily performed on tissue samples collected prospectively or from archived samples. Coupled with tissue microarray technology and the increasing number of available automated, quantitative systems to read these arrays, we now have an efficient method of validating biomarkers for prognostic and predictive capabilities and for the identification of drug development targets.

High levels of vascular endothelial growth factor and its receptors (VEGFR-1, VEGFR-2, neuropilin-1) are associated with worse outcome in breast cancer

Vascular endothelial growth factor has been shown to be up-regulated in breast cancers. Vascular endothelial growth factor receptors, VEGFR-1 and VEGFR-2, are the principal mediators of its effects. Together with VEGFR-1 and VEGFR-2, neuropilin-1 may act as a coreceptor for vascular endothelial growth factor. Although vascular endothelial growth factor exerts important effects on endothelial cells, VEGFRs are likely present on tumor cells as well. We used AQUA to analyze tumor-specific expression of vascular endothelial growth factor, VEGFR-1, VEGFR-2, and neuropilin-1 on a large cohort of breast cancer tissue microarray. Two-fold redundant arrays were constructed from 642 cases of primary breast adenocarcinomas. Automated image analysis with AQUA (Automated Quantitative Analysis) was then performed to determine a quantitative expression score. Scores from redundant arrays were normalized and averaged. Kaplan-Meier survival analysis showed that high levels of vascular endothelial growth factor, VEGFR-1, VEGFR-2, and neuropilin-1 were all significantly associated with survival (Miller Siegmeund corrected P = .0020, .0160, and .0320, respectively). In addition, vascular endothelial growth factor and neuropilin-1 retained a significant association with survival independent of other standard prognostic factors. Vascular endothelial growth factor, VEGFR-1 and -2, and neuropilin-1 are expressed to varying degrees in primary breast cancers and have prognostic significance. Further study of the functional significance of this finding is warranted as well as the prognostic value of these biomarkers in other tumor microenvironment-specific compartments (eg, vessels).

Update on molecular diagnostic tests in head and neck cancer

Head and neck cancers (HNCs) include several cancers originating in the upper airways that represent a variety of histologies. The most common type of HNC is squamous cell carcinoma (SCC), which is linked to tobacco and alcohol use and to human papilloma virus (HPV). At present, there are no standard molecular tests that are routinely used in clinics. This overview will discuss the current knowledge on molecular markers with the potential to be developed as diagnostic tests for cancer risk assessment, early detection, clinical response prediction to specific therapies, and prognosis. These markers are usually based on recent findings in tumor biology and genetic defects in HNC, and provide information both independently and in combination with currently available clinical parameters. In practice, many potential markers are difficult to measure due to assay variability, lack of standards for the interpretation of assay results, and incomplete knowledge of the effects on disease biology and response to treatment. However, there is great enthusiasm for the general concept of using molecular knowledge for the clinical management of HNC. Although it will be a great challenge to develop robust and reliable molecular diagnostic tests, the development of promising assays fueled by advances in science and technology will continue and will ultimately reach the goal of improving the care of HNC patients.

EGFR, p16, HPV Titer, Bcl-xL and p53, sex, and smoking as indicators of response to therapy and survival in oropharyngeal cancer

PURPOSE

To prospectively identify markers of response to therapy and outcome in an organ-sparing trial for advanced oropharyngeal cancer.

PATIENTS AND METHODS

Pretreatment biopsies were examined for expression of epidermal growth factor receptor (EGFR), p16, Bcl-xL, and p53 as well as for p53 mutation. These markers were assessed for association with high-risk human papillomavirus (HPV), response to therapy, and survival. Patient variables included smoking history, sex, age, primary site, tumor stage, and nodal status.

RESULTS

EGFR expression was inversely associated with response to induction chemotherapy (IC) (P = .01), chemotherapy/radiotherapy (CRT; P = .055), overall survival (OS; P = .001), and disease-specific survival (DSS; P = .002) and was directly associated with current smoking (P = .04), female sex (P = .053), and lower HPV titer (P = .03). HPV titer was significantly associated with p16 expression (P < .0001); p16 was significantly associated with response to IC (P = .008), CRT (P = .009), OS (P = .001), and DSS (P = .003). As combined markers, lower HPV titer and high EGFR expression were associated with worse OS (rho(EGFR) = 0.008; rho(HPV) = 0.03) and DSS (rho(EGFR) = 0.01; rho(HPV) = 0.016). In 36 of 42 biopsies, p53 was wild-type, and only one HPV-positive tumor had mutant p53. The combination of low p53 and high Bcl-xL expression was associated with poor OS (P = .005) and DSS (P = .002).

CONCLUSION

Low EGFR and high p16 (or higher HPV titer) expression are markers of good response to organ-sparing therapy and outcome, whereas high EGFR expression, combined low p53/high Bcl-xL expression, female sex, and smoking are associated with a poor outcome. Smoking cessation and strategies to target EGFR and Bcl-xL are important adjuncts to the treatment of oropharyngeal cancer.

Tissue microarrays in clinical oncology

Tissue microarray (TMA) is a recently implemented, high-throughput technology for the analysis of molecular markers in oncology. This research tool permits the rapid assessment of a biomarker in thousands of tumor samples, using commonly available laboratory assays such as immunohistochemistry and in situ hybridization. Although introduced less than a decade ago, TMA has proven to be invaluable in the study of tumor biology, the development of diagnostic tests, and the investigation of oncologic biomarkers. This review describes the impact of TMA-based research in clinical oncology and its potential future applications. Technical aspects of TMA construction and the advantages and disadvantages inherent to this technology are also discussed.

The radioprotector Bowman-Birk proteinase inhibitor stimulates DNA repair via epidermal growth factor receptor phosphorylation and nuclear transport

BACKGROUND AND PURPOSE

The purpose of the study was to elucidate the underlying molecular mechanism of the radioprotector, Bowman-Birk proteinase inhibitor (BBI), and its interaction with EGFR nuclear transport.

MATERIALS AND METHODS

Molecular effects of BBI at the level of EGFR responses were investigated in vitro with wt. TP53 bronchial carcinoma cell line A549 and the transformed fibroblast cell line HH4dd characterized by a mt. TP53. EGFR and associated protein expression were quantified by Western blotting and confocal microscopy in the cytoplasmic and nuclear cell fraction. Residual DNA double strand breaks were quantified by means of a gammaH(2)AX focus assay.

RESULTS

Both irradiation and BBI-treatment stimulated EGFR internalization into the cytoplasm. This process involved src kinase activation, EGFR phosphorylation at Y845, and caveolin 1 phosphorylation at Y14. EGFR internalization correlated with nuclear EGFR transport and was associated with phosphorylation of EGFR at T654. Nuclear EGFR was linked with DNA-PK complex formation and activation. Furthermore, nuclear EGFR was found in complex with TP53, phosphorylated at S15, and with MDC1, following irradiation and BBI treatment. It is noteworthy that MDC1 was strongly decreased in the nuclear EGFR complex in cells with mt. TP53 and failed to be increased by either BBI treatment or irradiation. Interestingly, in cells with mt. TP53 the BBI mediated stimulation of double strand break repair was hampered significantly.

CONCLUSION

These data indicate that BBI stimulates complex formation between EGFR, TP53 and MDC1 protein in wt. TP53 cells only. Since MDC1 is essential for recruitment of DNA repair foci, this observation may explain how BBI selectively stimulated repair of DNA double strand breaks in wt. TP53 cells.

Proliferation of Ewing sarcoma cell lines is suppressed by the receptor tyrosine kinase inhibitors gefitinib and vandetanib

Background

Tyrosine kinase inhibitors (TKIs) have gained much attention in recent years as targeted agents for the treatment of a wide range of human cancers. We have investigated the effect of the TKIs gefitinib and vandetanib on tumor cell lines derived from Ewing sarcoma, a highly malignant tumor affecting bone and soft tissue in children and young adults. Gefitinib is an inhibitor of epidermal growth factor receptor tyrosine kinase activity (EGFR) and vandetanib selectively targets vascular endothelial growth factor receptor-2 (VEGFR-2) with additional activity against VEGFR-3, EGFR and RET kinase receptors.

Results

Two Ewing sarcoma cell lines investigated showed high levels of nuclear EGFR expression as well as moderate expression in plasma membrane and cytoplasm. When treated with concentrations of 5 μM and more of either gefitinib or vandetanib, we observed a significant decrease in cell proliferation. However, there were no detectable changes in p44/42 MAPK and Akt-1 phosphorylation, or in the expression of cyclin D1 or c-Myc following gefitinib or vandetanib treatment.

Conclusion

We conclude that Ewing sarcoma tumor cell proliferation is not highly sensitive to inhibition of EGFR signaling alone or the simultaneous inhibition of VEGFR receptors, EGFR and RET kinase. Decreased tumor cell proliferation could be achieved with gefitinib and vandetanib, but only at higher doses where non-specific effects of the compounds may be overriding. As Ewing tumor cells do not seem to depend on EGFR and VEGFR pathways for survival, other key factors in the cellular signaling of Ewing sarcoma should be targeted in order to obtain a potent therapeutic response.

JAK-STAT pathway in carcinogenesis: Is it relevant to cholangiocarcinoma progression

The features of JAK-STAT signaling in liver cells are discussed in the current review. The role of this signaling cascade in carcinogenesis is accentuated. The possible involvement of this pathway and alteration of its elements are compared for normal cholangiocytes, cholangiocarcinoma predisposition and development. Prolactin and interleukin-6 are described in detail as the best studied examples. In addition, the non-classical nuclear translocation of cytokine receptors is discussed in terms of its possible implication to cholangiocarcinoma development.

Response to therapy and outcomes in oropharyngeal cancer are associated with biomarkers including human papillomavirus, epidermal growth factor receptor, gender, and smoking

Induction chemotherapy and concurrent chemoradiation for responders or immediate surgery for non-responders is an effective treatment strategy head and neck squamous cell carcinoma (HNSCC) of the larynx and oropharynx. Biomarkers that predict outcome would be valuable in selecting patients for therapy. In this study, the presence and titer of high risk human papilloma virus (HPV) and expression of epidermal growth factor receptor (EGFR) in pre-treatment biopsies, as well as smoking and gender were examined in oropharynx cancer patients enrolled in an organ sparing trial. HPV16 copy number was positively associated with response to therapy and with overall and disease specific survival, whereas EGFR expression, current or former smoking behavior, and female gender (in this cohort) were associated with poor response and poor survival in multivariate analysis. Smoking cessation and strategies to target EGFR may be useful adjuncts for therapy to improve outcome in the cases with the poorest biomarker profile.

Celecoxib induced tumor cell radiosensitization by inhibiting radiation induced nuclear EGFR transport and DNA-repair: a COX-2 independent mechanism

PURPOSE

The purpose of the study was to elucidate the molecular mechanisms mediating radiosensitization of human tumor cells by the selective cyclooxygenase (COX)-2 inhibitor celecoxib.

METHODS AND MATERIALS

Experiments were performed using bronchial carcinoma cells A549, transformed fibroblasts HH4dd, the FaDu head-and-neck tumor cells, the colon carcinoma cells HCT116, and normal fibroblasts HSF7. Effects of celecoxib treatment were assessed by clonogenic cell survival, Western analysis, and quantification of residual DNA damage by gammaH(2)AX foci assay.

RESULTS

Celecoxib treatment resulted in a pronounced radiosensitization of A549, HCT116, and HSF7 cells, whereas FaDu and HH4dd cells were not radiosensitized. The observed radiosensitization could neither be correlated with basal COX-2 expression pattern nor with basal production of prostaglandin E2, but was depended on the ability of celecoxib to inhibit basal and radiation-induced nuclear transport of epidermal growth factor receptor (EGFR). The nuclear EGFR transport was strongly inhibited in A549-, HSF7-, and COX-2-deficient HCT116 cells, which were radiosensitized, but not in FaDu and HH4dd cells, which resisted celecoxib-induced radiosensitization. Celecoxib inhibited radiation-induced DNA-PK activation in A549, HSF7, and HCT116 cells, but not in FaDu and HH4dd cells. Consequentially, celecoxib increased residual gammaH2AX foci after irradiation, demonstrating that inhibition of DNA repair has occurred in responsive A549, HCT116, and HSF7 cells only.

CONCLUSIONS

Celecoxib enhanced radiosensitivity by inhibition of EGFR-mediated mechanisms of radioresistance, a signaling that was independent of COX-2 activity. This novel observation may have therapeutic implications such that COX-2 inhibitors may improve therapeutic efficacy of radiation even in patients whose tumor radioresistance is not dependent on COX-2.

Use of Molecular Biomarkers for Predicting the Response to Radiotherapy With or Without Chemotherapy

Radiotherapy (RT), particularly when combined with chemotherapy, has progressively become the nonsurgical standard of care in the primary treatment of a variety of cancers. Likewise, hormonal therapy is routinely combined with RT for the treatment of hormone-sensitive tumors. In addition, the clinical efficacy of combining an epidermal growth factor receptor (EGFR) antagonist with RT was recently validated. In view of cancer heterogeneity and the availability of an increasing number of therapy options, identification of biomarkers that can predict tumor response to a given therapy is crucial in streamlining treatment and sparing patients from receiving often toxic and expensive therapies that are not likely to be effective. Well-established biomarkers for response to hormonal therapy and/or RT are tumor estrogen receptor and the receptor tyrosine kinase HER-2 for breast cancer and serum prostate-specific antigen for prostate carcinoma. Some markers of tumor hypoxia and the level of tumor EGFR expression have been shown to be independent predictors of tumor response to RT. The use of biomarkers for predicting tumor response to the combination of RT and chemotherapy has thus far been limited to the methylation status of O-6-methylguanine-DNA methyltransferase in patients with glioblastoma multiforme treated with the combination of RT plus temozolomide. No validated biomarkers for predicting the response to molecular therapeutics are currently available. In this review, we call for standardization and simplification of assay methods and stress the importance of conducting confirmatory prospective studies. Integrated plans for identifying molecular markers built into many ongoing trials will hopefully generate more insights in the near future.

Phase II Trial of Sorafenib in Patients With Recurrent or Metastatic Squamous Cell Carcinoma of the Head and Neck or Nasopharyngeal Carcinoma

Purpose

To determine the efficacy and safety of single-agent sorafenib in patients with recurrent and/or metastatic squamous cell carcinoma of the head and neck (SCCHN) and nasopharyngeal carcinoma (NPC).

Patients and Methods

In this single-arm phase II trial, oral continuous sorafenib was administered in 28-day cycles. Patients had ≤ one line of chemotherapy for recurrent and/or metastatic disease, Eastern Cooperative Oncology Group performance status of ≤ 2, and adequate organ function. At the end of stage 1, efficacy criteria for further accrual were not met, but the study was amended to enroll an additional five patients for paired tumor biopsies.

Results

Twenty-seven and 26 patients were eligible for toxicity and efficacy evaluations, respectively. One patient (3.7%; 95% CI, 0.1% to 19.0%) achieved a partial response. Disease stabilization was maintained in 10 patients (37.0%; 95% CI, 22.4% to 61.2%). The median time to progression was 1.8 months (95% CI, 1.6 to 3.4 months), and median overall survival time was 4.2 months (95% CI, 3.6 to 8.7 months). Sorafenib was well tolerated with few grade 3 and no grade 4 toxicities. Biomarker analysis of paired tumor samples before and after treatment with sorafenib revealed a decrease of pERK in all five patients, with a decrease in Ki67 in four patients, consistent with a disruption of ERK signaling. The antiapoptotic protein Mcl-1 was downregulated in four patients, and there was also evidence of antiangiogenic activity.

Conclusion

Sorafenib was well tolerated and had modest anticancer activity comparable to monotherapy with other targeted agents in this group of patients. Further development in combination with radiation or other agents may be warranted.

Quantitative analysis of estrogen receptor heterogeneity in breast cancer

Immunohistochemical analyses (IHC) of biomarkers are extensively used for tumor characterization and as prognostic and predictive measures. The current standard of single slide analysis assumes that one 5 microM section is representative of the entire tumor. We used our automated image analysis technology (AQUA) using a modified IHC technique with fluorophores to compare estrogen receptor (ER) expression in multiple blocks/slides from cases of primary breast cancer with the objective of quantifying tumor heterogeneity within sections and between blocks. To normalize our ER scores and allow slide-to-slide comparisons, 0.6 microm histospots of representative breast cancer cases with known ER scores were assembled into a 'gold standard array' (GSA) and placed adjacently to each whole section. Overall, there was excellent correlation between AQUA scores and the pathologist's scores and reproducibility of GSA scores (mean linear regression R value 0.8903). Twenty-nine slides from 11 surgical cases were then analyzed totaling over 2000 AQUA images. Using standard binary assignments of AQUA (>10) and pathologist's (>10%) scores as being positive, there was fair concordancy between AQUA and pathologist scores (73%) and between slides from different blocks from the same cases (75%). However using continuous AQUA scores, agreement between AQUA and pathologist was far lower and between slides from different blocks from the same cases only 19%. Within individual slides there was also significant heterogeneity in a scattered pattern, most notably for slides with the highest AQUA scores. In sum, using a quantitative measure of ER expression, significant block-to-block heterogeneity was found in 81% of cases. These results most likely reflect both laboratory-based variability due to lack of standardization of immunohistochemistry and true biological heterogeneity. It is also likely to be dependent on the biomarker analyzed and suggests further studies should be carried out to determine how these findings may affect clinical decision-making processes.

Her signaling in pancreatic cancer

Pancreatic cancer remains a treatment-refractory cancer. Standard therapy for metastatic cancer is gemcitabine chemotherapy, with a median survival of 5-6 months. The epidermal growth factor receptor (EGFR) is commonly expressed in pancreatic cancer and has been evaluated as a therapeutic target. A Phase III trial of gemcitabine with or without the EGFR inhibitor, erlotinib, demonstrated a modest but significant prolongation of survival with the addition of erlotinib. A Phase II trial of gemcitabine with the anti-EGFR antibody cetuximab resulted in a 1-year survival of 32%. A Phase III trial of gemcitabine with or without cetuximab and a randomized Phase II trial of the Murren regimen with or without cetuximab are completed; results for both are anticipated in 2007. A Phase I trial of gemcitabine with the EGFR/Her-2 inhibitor, lapatinib, is completed. Improved patient selection and rational combination of targeted therapies will be necessary to optimize the management of patients with this tragic disease.

Clinical and prognostic significances of nuclear and cytoplasmic KIT expressions in extrahepatic bile duct carcinomas

After receiving FDA approval as a therapeutic regimen in gastrointestinal stromal tumors, the tyrosine kinase inhibitor imatinib mesylate has been applied to the treatment of other solid malignant neoplasms. To evaluate the usefulness of imatinib mesylate as a possible therapeutic regimen in extrahepatic bile duct carcinomas, an immunohistochemical study for KIT was performed in 289 cases of extrahepatic bile duct carcinomas, and mutational analysis of exon 11 of the c-kit gene was performed in 20 cases that were arbitrarily retrieved from the cases with KIT expression. Cytoplasmic KIT expression was observed in 54 cases (19%) and nuclear KIT in 58 cases (20%) of extrahepatic bile duct carcinoma. Nuclear KIT expression was more frequent in cases with vascular invasion (P<0.001), whereas cytoplasmic KIT expression was more common in tumors of T1-T3 than in those of T4 (P=0.04), and was more frequently observed in cases with a papillary growth pattern (P=0.03). Patients with cytoplasmic KIT-positive tumors had significantly better survival both by univariate (P=0.01) and multivariate analyses (P=0.04). Infrequent cytoplasmic KIT expression without mutation of exon 11 suggests that imatinib mesylate may not be effective for the treatment of extrahepatic bile duct carcinoma. However, immunohistochemical study for KIT may be helpful in routine pathologic examinations for evaluating better prognosis for patients with extrahepatic bile duct carcinoma. In addition, more frequent nuclear expression of KIT in cases with vascular invasion suggests that nuclear KIT expression may contribute to the progression of extrahepatic bile duct carcinoma.

Association of epidermal growth factor receptor (EGFR) gene copy number amplification with neck lymph node metastasis in areca-associated oral carcinomas

Epidermal growth factor receptor (EGFR) has an important role in cell proliferation, differentiation, and transformation. Several alterations and activation of EGFR have been identified in tumors. Inhibitors that impair EGFR activity have been identified and studied for cancer therapy, so the present study was conducted to comprehensively assess the amplification, mutation, and expression of EGFR in areca-associated oral squamous cell carcinoma (OSCC), which might be beneficial for targeting therapy. Gene copy number amplifications of EGFR were identified in 33% (14/42) cases of OSCC. Six cases of OSCC had a high copy number amplification. Direct sequencing of PCR products of 20 representative cases of OSCC revealed no somatic mutation in the kinase domains of EGFR. Sixty-seven percent (28/42) of the OSCC cases had nuclear and/or cytosolic EGFR immunoreactivity. Significant increases in EGFR copy number and EGFR immunoreactivity were found in OSCC subjects compared with long-term areca chewers, or compared with match adjacent oral mucosa (P<0.0001 and P=0.029, respectively). Interestingly, OSCC with nodal involvement had significantly higher EGFR gene copy number than OSCC without nodal involvement (3.194+/-0.740 versus 1.733+/-0.246; P=0.050). Our data suggest that genomic amplification could be a genetic basis underlying activation of the EGFR pathway in areca-associated OSCC.

Combination of radiotherapy with EGFR antagonists for head and neck carcinoma

The introduction of biologically sound radiation fractionation regimens and combinations of radiotherapy with chemotherapy have gradually improved both the survival of patients with locally advanced head and neck squamous cell carcinoma (HNSCC) and the prospect of organ preservation. Long-term follow-up, however, has shown that some of the radiation-chemotherapy combinations are associated with increased late toxicity. This observation, in conjunction with advances in tumor biology, has led to the launch of investigations into molecular markers and targets for therapeutic interventions. Research on the epidermal growth factor receptor (EGFR)-mediated signaling pathway has enriched our understanding of the biology of HNSCC, in terms of carcinogenesis and cellular processes governing tumor response to therapy. The finding that the addition of an antibody-based inhibitor of the EGFR pathway to radiotherapy significantly improves locoregional control and overall survival rates in patients with locally advanced HNSCC, without increasing radiation-induced toxicity, has resulted in the growing acceptance of such combined regimens as a frontline therapy option for locally advanced HNSCC. Because such therapy has benefited only an additional 10%-15% of patients, studies are being undertaken to identify markers and mechanisms of resistance to EGFR antagonists that are essential for the further refinement of therapy. Overall, preclinical and clinical studies on EGFR have validated the concept that selective tumor radiation sensitization can be achieved by modulating a specific perturbed signaling pathway, and these studies have increased the enthusiasm for developing and investigating other novel agents targeting other cellular processes.

Combined analysis of HPV-DNA, p16 and EGFR expression to predict prognosis in oropharyngeal cancer

Molecular prognostic indicators for oropharyngeal squamous cell carcinoma (OSCC), including HPV-DNA detection, epidermal growth factor receptor (EGFR) and p16 expression, have been suggested in the literature, but none of these are currently used in clinical practice. To compare these predictors, 106 newly diagnosed OSCC for the presence of HPV-DNA and expression of p16 and EGFR were analyzed. The 5-year disease-free survival (DFS) and overall survival (OS) were calculated in relation to these markers and a multivariate Cox analysis was performed. Twenty-eight percent of the cases contained oncogenic HPV-DNA and 30% were positive for p16. The p16 expression was highly correlated with the presence of HPV-DNA (p < 0.001). Univariate analysis of the 5-year DFS revealed a significantly better outcome for patients with p16-positive tumors (84% vs. 49%, p = 0.009). EGFR-negative tumors showed a tendency toward a better prognosis in DFS (74% vs. 47%, p = 0.084) and OS (70% vs. 45%, p = 0.100). Remarkable and highly significant was the combination of p16 and EGFR expression status, leading to 5-year DFS of 93% for p16+/EGFR- tumors vs. 39% for p16-/EGFR+ tumors (p = 0.003) and to a 5-year OS of 79% vs. 38%, respectively (p = 0.010). In multivariate analysis p16 remained a highly significant prognostic marker for DFS (p = 0.030) showing a 7.5-fold increased risk for relapse in patients with p16-negative tumors. Our data indicate that p16 expression is the most reliable prognostic marker for OSCC and further might be a surrogate marker for HPV-positive OSCC. HPV+/p16+ tumors tended to have decreased EGFR expression, but using both immunohistological markers has significant prognostic implications.

The EGF receptor family: spearheading a merger of signaling and therapeutics

The ErbB receptor tyrosine kinases evolved as key regulatory entities enabling the extracellular milieu to communicate with the intracellular machinery to bring forth the appropriate biological response in an ever-changing environment. Since its discovery, many aspects of the ErbB family have been deciphered, with emphasis on aberration of signaling in human diseases. However, only now, with the availability of the atomic coordinates of these receptors, can we construct a comprehensive model of the mechanisms underlying ligand-induced receptor dimerization and subsequent tyrosine kinase activation. Furthermore, the recent introduction of new high-throughput screening methodologies, combined with the materialization of a systems biology perspective, reveals an overwhelming network complexity, enabling robust signaling and evolvability. This knowledge is likely to impact our view of diseases as system perturbations and resistance to ErbB-targeted therapeutics as manifestations of robustness.

Role of the Sec61 translocon in EGF receptor trafficking to the nucleus and gene expression

The epidermal growth factor (EGF)-dependent trafficking of the intact EGF receptor to the nucleus and its requirement for growth factor induction of cyclin D and other genes has been reported. Unresolved is the mechanism by which this or other transmembrane proteins are excised from a lipid bilayer before nuclear translocalization. We report that, after the addition of EGF, the cell surface EGF receptor is trafficked to the endoplasmic reticulum (ER) where it associates with Sec61beta, a component of the Sec61 translocon, and is retrotranslocated from the ER to the cytoplasm. Abrogation of Sec61beta expression prevents EGF-dependent localization of EGF receptors to the nucleus and expression of cyclin D. This indicates that EGF receptors are trafficked from the ER to the nucleus by a novel pathway that involves the Sec61 translocon.

Microarrays as validation strategies in clinical samples: tissue and protein microarrays

The widespread use of DNA microarrays has led to the discovery of many genes whose expression profile may have significant clinical relevance. The translation of this data to the bedside requires that gene expression be validated as protein expression, and that annotated clinical samples be available for correlative and quantitative studies to assess clinical context and usefulness of putative biomarkers. We review two microarray platforms developed to facilitate the clinical validation of candidate biomarkers: tissue microarrays and reverse-phase protein microarrays. Tissue microarrays are arrays of core biopsies obtained from paraffin-embedded tissues, which can be assayed for histologically-specific protein expression by immunohistochemistry. Reverse-phase protein microarrays consist of arrays of cell lysates or, more recently, plasma or serum samples, which can be assayed for protein quantity and for the presence of post-translational modifications such as phosphorylation. Although these platforms are limited by the availability of validated antibodies, both enable the preservation of precious clinical samples as well as experimental standardization in a high-throughput manner proper to microarray technologies. While tissue microarrays are rapidly becoming a mainstay of translational research, reverse-phase protein microarrays require further technical refinements and validation prior to their widespread adoption by research laboratories.

Tyrosine phosphorylation controls PCNA function through protein stability

The proliferating cell nuclear antigen (PCNA) is an essential protein for DNA replication and damage repair. How its function is controlled remains an important question. Here, we show that the chromatin-bound PCNA protein is phosphorylated on Tyr 211, which is required for maintaining its function on chromatin and is dependent on the tyrosine kinase activity of EGF receptor (EGFR) in the nucleus. Phosphorylation on Tyr 211 by EGFR stabilizes chromatin-bound PCNA protein and associated functions. Consistently, increased PCNA Tyr 211 phosphorylation coincides with pronounced cell proliferation, and is better correlated with poor survival of breast cancer patients, as well as nuclear EGFR in tumours, than is the total PCNA level. These results identify a novel nuclear mechanism linking tyrosine kinase receptor function with the regulation of the PCNA sliding clamp.

Nuclear trafficking of secreted factors and cell-surface receptors: new pathways to regulate cell proliferation and differentiation, and involvement in cancers

Secreted factors and cell surface receptors can be internalized by endocytosis and translocated to the cytoplasm. Instead of being recycled or proteolysed, they sometimes translocate to the nucleus. Nuclear import generally involves a nuclear localization signal contained either in the secreted factor or its transmembrane receptor, that is recognized by the importins machinery. In the nucleus, these molecules regulate transcription of specific target genes by direct binding to transcription factors or general coregulators. In addition to the transcription regulation, nuclear secreted proteins and receptors seem to be involved in other important processes for cell life and cellular integrity such as DNA replication, DNA repair and RNA metabolism.

Nuclear secreted proteins and transmembrane receptors now appear to induce new signaling pathways to regulate cell proliferation and differentiation. Their nuclear localization is often transient, appearing only during certain phases of the cell cycle. Nuclear secreted and transmembrane molecules regulate the proliferation and differentiation of a large panel of cell types during embryogenesis and adulthood and are also potentially involved in wound healing. Secreted factors such as CCN proteins, EGF, FGFs and their receptors are often detected in the nucleus of cancer cells. Nuclear localization of these molecules has been correlated with tumor progression and poor prognosis for patient survival. Nuclear growth factors and receptors may be responsible for resistance to radiotherapy.

Increased epidermal growth factor receptor gene copy number is associated with poor prognosis in head and neck squamous cell carcinomas

PURPOSE

High epidermal growth factor receptor (EGFR) gene copy number is associated with poor prognosis in lung cancer, but such findings have not been reported for HNSCC. A better understanding of the EGFR pathway may improve the use of EGFR inhibitors in HNSCC.

PATIENTS AND METHODS

EGFR status was analyzed in 86 tumor samples from 82 HNSCC patients by fluorescent in situ hybridization (FISH) to determine EGFR gene copy number, by polymerase chain reaction and direct sequencing for activating mutations, and by DNA microarray and immunohistochemistry for RNA and protein expression. The results were associated with patient characteristics and clinical end points.

RESULTS

Forty-three (58%) of 75 samples with FISH results demonstrated EGFR high polysomy and/or gene amplification (FISH positive). The FISH-positive group did not differ from the FISH-negative group with respect to age, sex, race, tumor grade, subsites and stage, or EGFR expression by analyses of RNA or protein. No activating EGFR mutations were found. However, the FISH-positive group was associated with worse progression-free and overall survival (P < .05 and P < .01, respectively; log-rank test). When microarray data were interrogated using the FISH results as a supervising parameter, ECop (which is known to coamplify with EGFR and regulate nuclear factor-kappa B transcriptional activity) had higher expression in FISH-positive tumors.

CONCLUSION

High EGFR gene copy number by FISH is frequent in HNSCC and is a poor prognostic indicator. Additional investigation is indicated to determine the biologic significance and implications for EGFR inhibitor therapies in HNSCC.

Epidermal growth factor receptor biology in head and neck cancer

Epidermal growth factor receptor (EGFR) is overexpressed in several epithelial malignancies, including head and neck squamous cell carcinoma (HNSCC), which exhibits EGFR overexpression in up to 90% of tumors. EGFR ligands such as transforming growth factor alpha are also overexpressed in HNSCC. EGFR plays a critical role in HNSCC growth, invasion, metastasis and angiogenesis. However, EGFR inhibitors as monotherapy have yielded only modest clinical outcomes. Potential mechanisms for lack of response to EGFR inhibition in HNSCC include constitutive activation of signaling pathways independent of EGFR, as well as genetic aberrations causing dysregulation of the cell cycle. EGFR-directed therapy may be optimized by identifying and selecting those HNSCC patients most likely to benefit from EGFR inhibition. Resistance to EGFR inhibition may be circumvented by combination therapy employing EGFR inhibitors together with other treatment modalities.

Nuclear-cytoplasmic transport of EGFR involves receptor endocytosis, importin beta1 and CRM1

Many receptor tyrosine kinases (RTKs) can be detected in the cell nucleus, such as EGFR, HER-2, HER-3, HER-4, and fibroblast growth factor receptor. EGFR, HER-2 and HER-4 contain transactivational activity and function as transcription co-factors to activate gene promoters. High EGFR in tumor nuclei correlates with increased tumor proliferation and poor survival in cancer patients. However, the mechanism by which cell-surface EGFR translocates into the cell nucleus remains largely unknown. Here, we found that EGFR co-localizes and interacts with importins alpha1/beta1, carriers that are critical for macromolecules nuclear import. EGFR variant mutated at the nuclear localization signal (NLS) is defective in associating with importins and in entering the nuclei indicating that EGFR's NLS is critical for EGFR/importins interaction and EGFR nuclear import. Moreover, disruption of receptor internalization process using chemicals and forced expression of dominant-negative Dynamin II mutant suppressed nuclear entry of EGFR. Additional evidences suggest an involvement of endosomal sorting machinery in EGFR nuclear translocalization. Finally, we found that nuclear export of EGFR may involve CRM1 exportin as we detected EGFR/CRM1 interaction and markedly increased nuclear EGFR following exposure to leptomycin B, a CRM1 inhibitor. Collectively, these data suggest the importance of receptor endocytosis, endosomal sorting machinery, interaction with importins alpha1/beta1, and exportin CRM1 in EGFR nuclear-cytoplasmic trafficking. Together, our work sheds light into the nature and regulation of the nuclear EGFR pathway and provides a plausible mechanism by which cells shuttle cell-surface EGFR and potentially other RTKs through the nuclear pore complex and into the nuclear compartment.

Nuclear EGFR signalling network in cancers: linking EGFR pathway to cell cycle progression, nitric oxide pathway and patient survival

Emerging evidences suggest the existence of a new mode of epidermal growth factor receptor (EGFR) signalling pathway in which activated EGFR undergoes nuclear translocalization and subsequently regulates gene expression and potentially mediates other cellular processes. This signalling route is distinct from the better-characterized, traditional EGFR pathway that involves transduction of mitogenic signals through activation of multiple signalling cascades. Transcriptional activity of nuclear EGFR appears to depend on its C-terminal transactivation domain and its physical and functional interaction with other transcription factors that contain DNA-binding activity. Likely via its ability to upregulate gene expression, nuclear EGFR pathway is associated with major characteristics of more aggressive tumours: increased proliferative potential, nitric oxide synthesis, and accelerated G1/S cell cycle progression. A role of nuclear EGFR in prognostic prediction is further suggested in patients with breast carcinomas and oropharyngeal squamous cell carcinomas. It is noted that significant advances were made towards the knowledge of the nuclear EGFR pathway; however, many aspects of this new pathway remain unresolved and will be discussed in this review. As a number of other receptor tyrosine kinases (RTKs) and cytokine receptors also undergo similar nuclear translocalization, a better understanding of the physiological and malignant nature of the nuclear EGFR pathway will likely shed light into the biology of cancer with nuclear RTKs.

Immunohistochemical analysis of EGFR and HER-2 in patients with metastatic squamous cell carcinoma of the skin

BACKGROUND

Metastatic squamous cell carcinoma (SCC) of the skin often raise difficult therapeutic problems. Few data are available about the expression of EGFR and HER-2 in SCC of the skin. Overexpression of EGFR and of HER-2 proteins has been reported. The purpose of this study was to investigate the expression of EGFR and HER-2 in a series of metastatic SCC of the skin.

PATIENTS AND METHODS

EGFR and HER-2 expression was studied by immunochemistry on 13 specimens of metastatic recurrence and on 2 primary lesions of these tumours.

RESULTS

EGFR had a strong membranous expression in all specimens. HER-2 was weakly expressed in 4 specimens, with a membrane expression in 2 cases.

CONCLUSION

In the present study, EGFR was overexpressed in all samples of metastatic SCCs of the skin. Therefore, these metastatic tumours appear to be suitable targets for treatment with tyrosine kinase inhibitors. Additional studies are warranted to establish whether or not HER-2 is expressed in SCC of the skin.