Determinants of response to epidermal growth factor receptor tyrosine kinase inhibition in squamous cell carcinoma of the head and neck

Amphiregulin in cellular physiology, health, and disease: Potential use as a biomarker and therapeutic target

Amphiregulin (AREG), which acts as one of the ligands for epidermal receptor growth factor receptor (EGFR), plays a crucial role in tissue repair, inflammation, and immunity. AREG is synthesized as membrane-anchored pre-protein, and is excreted after proteolytic cleavage, and serves as an autocrine or paracrine factor. After engagement with the EGFR, AREG triggers a cascade of signaling events required for many cellular physiological processes including metabolism, cell cycle, and proliferation. Under different inflammatory and pathogenic conditions, AREG is expressed by various activated immune cells that orchestrate both tolerance and host resistance mechanisms. Several factors including xenobiotics, cytokines, and inflammatory lipids have been shown to trigger AREG gene expression and release. In this review, we discuss the structure, function, and regulation of AREG, its role in tissue repair, inflammation, and homeostasis as well as the potential of AREG as a biomarker and therapeutic target.

Cigarette Smoke Containing Acrolein Upregulates EGFR Signaling Contributing to Oral Tumorigenesis In Vitro and In Vivo

Oral squamous cell carcinoma (OSCC) accounts for 80-90% of all intraoral malignant neoplasms. The single greatest risk factor for oral cancer is tobacco use, including cigarettes, cigars, chewing tobacco, and snuff. Aberrations of the epidermal growth factor receptor (EGFR) pathway features prominently in oral tumorigenesis and progression. It was shown that cigarette smoking (CS) is associated with worse prognosis in OSCC patients and overexpression of EGFR in tumor tissue. However, the mechanism by which cigarette smoking induced EGFR pathway activation remains to be fully elucidated. Acrolein, an IARC group 2A carcinogen, is a highly reactive aldehyde found in CS. Here we report that acrolein is capable of inducing tumorigenic transformation in normal human oral keratinocytes (NOK). The acrolein-transformed NOK cells showed EGFR copy number amplification, increased EGFR expression, and activation of downstream ERK and AKT signaling pathway. No p53 mutations were observed in acrolein-transformed NOK cells. Inhibiting EGFR pathway using an anti-EGFR antibody, cetuximab, inhibits tumor growth. Furthermore, by examining tissue sample from patients, we found an increased EGFR copy number was positively associated with acrolein-induced DNA damages in OSCC patients. Taken together, our results indicate that acrolein is important in tumorigenic transformation through amplification of EGFR and activating the downstream signaling pathway, contributing to oral carcinogenesis. This is the first study to provide molecular evidence showing that CS containing acrolein contributes to EGFR amplification in OSCC.

The PERK Inhibitor GSK2606414 Enhances Reovirus Infection in Head and Neck Squamous Cell Carcinoma via an ATF4-Dependent Mechanism

Reovirus type 3 Dearing (reovirus) is a tumor-selective oncolytic virus currently under evaluation in clinical trials. Here, we report that the therapeutic efficacy of reovirus in head and neck squamous cell cancer can be enhanced by targeting the unfolded protein response (UPR) kinase, protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK). PERK inhibition by GSK2606414 increased reovirus efficacy in both 2D and 3D models in vitro, while perturbing the normal host cell response to reovirus-induced endoplasmic reticulum (ER) stress. UPR reporter constructs were used for live-cell 3D spheroid imaging. Profiling of eIF2a-ATF4, IRE1a-XBP1, and ATF6 pathway activity revealed a context-dependent increase in eIF2a-ATF4 signaling due to GSK2606414. GSK2606414 blocked eIF2a-ATF4 signaling because of the canonical ER stress agent thapsigargin. In the context of reovirus infection, GSK2606414 induced eIF2a-ATF4 signaling. Knockdown of eIF2a kinases PERK, GCN2, and PKR revealed eIF2a-ATF4 reporter activity was dependent on either PERK or GCN2. Knockdown of ATF4 abrogated the GSK2606414-induced increase in reovirus protein levels, confirming eIF2a-ATF signaling as key to the observed phenotype. Our work identifies a novel approach to enhance the efficacy and replication of reovirus in a therapeutic setting.

Effects of AQP5 gene silencing on proliferation, migration and apoptosis of human glioma cells through regulating EGFR/ERK/ p38 MAPK signaling pathway

We investigated the effects of aquaporin 5 (AQP5) gene silencing on the proliferation, migration and apoptosis of human glioma cells through regulating the EGFR/ERK/p38MAPK signaling pathway. qRT-PCR was applied to examine the mRNA expressions of AQP5 in five human glioma cell lines. U87-MG, U251 and LN229 cells were selected and assigned into blank, vector, AQP5 siRNA and FlagAQP5 groups. MTT assay was used to measure cell proliferation. Flow cytometry (FCM) with AnnexinV-FITC/PI double staining and PI staining were employed to analyze cell apoptosis and cell cycle respectively. Scratch test was used to detect cell migration. Western blotting was performed to determine the EGFR/ERK/p38 MAPK signaling pathway-related proteins. Results showed that the positive expression of AQP5 in primary glioblastoma was associated with the tumor size and whether complete excision was performed. The mRNA expressions of AQP5 in cell lines of U87-MG, U251 and LN229 were significantly higher than in U373 and T98G. The proliferation rates of U87-MG, U251 and LN229 cells in the AQP5 siRNA group were lower than in the vector and blank groups. The apoptosis rate increased in the AQP5 siRNA group compared with the vector group. Scratch test demonstrated that AQP5 gene silencing could suppress cell migration. Compared with the vector and blank groups, the AQP5 siRNA group showed decreased expressions of the ERK1/2, p38 MAPK, p-ERK1/2 and p-p38 MAPK proteins. AQP5 gene silencing could inhibit the cell proliferation, reduce cell migration and promote the cell apoptosis of U87-MG, U251 and LN229 by suppressing EGFR/ERK/p38 MAPK signaling pathway.

MAPK1E322K mutation increases head and neck squamous cell carcinoma sensitivity to erlotinib through enhanced secretion of amphiregulin

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have not been effective in unselected head and neck squamous cell carcinoma (HNSCC) populations. We previously reported an exceptional response to a brief course of erlotinib in a patient with advanced HNSCC whose tumor harbored a MAPK1^E322K somatic mutation. MAPK1^E322Kwas associated with increased p-EGFR, increased EGFR downstream signaling and increased sensitivity to erlotinib. In this study, we investigated the mechanism of MAPK1^E322K-mediated EGFR activation in the context of erlotinib sensitivity. We demonstrated increased AREG secretion in HNSCC cell lines harboring endogenous or exogenous MAPK1^E322K compared to wild type MAPK1. We found inhibition or knockdown of MAPK1 with siRNA resulted in reduced secretion of AREG and decreased sensitivity to erlotinib in the setting of MAPK1^E322K. MAPK1^E322K was associated with increased AREG secretion leading to an autocrine feedback loop involving AREG, EGFR and downstream signaling. Knockdown of AREG in HNSCC cells harboring MAPK1^E322K abrogated EGFR signaling and decreased sensitivity to erlotinib in vitro and in vivo. These cumulative findings implicate increased AREG secretion and EGFR activation as contributing to increased erlotinib sensitivity in MAPK1^E322K HNSCC.

Epidermal growth factor (EGF) receptor-ligand based molecular staging predicts prognosis in head and neck squamous cell carcinoma partly due to deregulated EGF- induced amphiregulin expression

BACKGROUND

Increased expression of epidermal growth factor receptor (EGFR) and its ligands is associated with poor prognosis and chemoresistance in many carcinoma types, but its role in head and neck squamous cell carcinoma (HNSCC) is unclear. Our aim was to clarify whether mRNA expression of EGFR-ligands was linked to prognosis and cisplatin resistance, and if so, which ligand was most important and how was the expression regulated.

METHODS

To examine the prognostic effect of EGFR-ligand expression, we analyzed tumorous mRNA expression in 399 HNSCC patients. The intracellular signaling pathways controlling epidermal growth factor (EGF)-induced amphiregulin (AREG) expression were examined in three oral squamous cell carcinoma (OSCC) cell lines. Effect of AREG on cisplatin resistance was examined by viability assays in four-, and by association in 11 OSCC cell lines.

RESULTS

The patients were divided into five groups according to the median mRNA expression levels of four EGFR ligands, i.e. AREG, EGF, heparin-binding EGF-like growth factor (HBEGF) and beta-cellulin (BTC). The number of increased-expressed EGFR-ligands were progressively correlated to five-year survival, even in advanced TNM-stage IV patients, where five-year mortality increased from 26 % if tumor expressed none to one EGFR-ligand, to 45 % in three to four ligand expressing tumors. Thus, staging the tumor according to these EGFR-ligand mRNA expression pattern completely out performed TNM staging in predicting prognosis. Multivariate analysis identified AREG as the dominating predictor, and AREG was overexpressed in OSCC compared to tumors from other sites. Both EGF and HBEGF stimulation induced strong AREG increase in OSCC cell lines, which was partially mediated by the extracellular signal-regulated kinase 1/2 pathway, and negatively regulated by p38, c-Jun N-terminal kinase, and phosphoinositide-3 kinase. Although increased AREG mRNA expression predicted unfavorable prognosis in platinum treated HNSCC patients, AREG did not mediate cisplatin resistance in the OSCC cell lines.

CONCLUSIONS

Increased tumorous mRNA expression of four EGFR ligands was progressively associated with poor prognosis in HNSCC. Thus, EGFR-ligands mRNA expression pattern may be a new prognostic biomarker. The tightly regulated EGF-induced AREG mRNA expression was partly lost in the OSCC cell lines and restoring its regulation may be a new target in cancer treatment.

TRIAL REGISTRATION

Not applicable as the clinical data of the 498 HNSCC patients and their mRNA expression profiles were collected from the open TCGA database: http://cancergenome.nih.gov/cancersselected/headandneck .

Acquired resistance to EGFR tyrosine kinase inhibitors alters the metabolism of human head and neck squamous carcinoma cells and xenograft tumours

BACKGROUND

Acquired resistance to molecularly targeted therapeutics is a key challenge in personalised cancer medicine, highlighting the need for identifying the underlying mechanisms and early biomarkers of relapse, in order to guide subsequent patient management.

METHODS

Here we use human head and neck squamous cell carcinoma (HNSCC) models and nuclear magnetic resonance (NMR) spectroscopy to assess the metabolic changes that follow acquired resistance to EGFR tyrosine kinase inhibitors (TKIs), and which could serve as potential metabolic biomarkers of drug resistance.

RESULTS

Comparison of NMR metabolite profiles obtained from control (CAL(S)) and EGFR TKI-resistant (CAL(R)) cells grown as 2D monolayers, 3D spheroids or xenograft tumours in athymic mice revealed a number of differences between the sensitive and drug-resistant models. In particular, we observed elevated levels of glycerophosphocholine (GPC) in CAL(R) relative to CAL(S) monolayers, spheroids and tumours, independent of the growth rate or environment. In addition, there was an increase in alanine, aspartate and creatine+phosphocreatine in resistant spheroids and xenografts, and increased levels of lactate, branched-chain amino acids and a fall in phosphoethanolamine only in xenografts. The xenograft lactate build-up was associated with an increased expression of the glucose transporter GLUT-1, whereas the rise in GPC was attributed to inhibition of GPC phosphodiesterase. Reduced glycerophosphocholine (GPC) and phosphocholine were observed in a second HNSCC model probably indicative of a different drug resistance mechanism.

CONCLUSIONS

Our studies reveal metabolic signatures associated not only with acquired EGFR TKI resistance but also growth pattern, microenvironment and contributing mechanisms in HNSCC models. These findings warrant further investigation as metabolic biomarkers of disease relapse in the clinic.

A novel serum protein signature associated with resistance to epidermal growth factor receptor tyrosine kinase inhibitors in head and neck squamous cell carcinoma

BACKGROUND

Acquired resistance to tyrosine kinase inhibitors (TKIs) is becoming a major challenge in the treatment of many cancers. Epidermal growth factor receptor (EGFR) is overexpressed in squamous carcinomas, notably those of the head and neck (HNSCC), and can be targeted with several TKIs. We aimed to identify soluble proteins suitable for development as markers of EGFR TKI resistance in cancer patients to aid in early and minimally invasive assessment of therapeutic responses.

METHODS

Resistant HNSCC cell lines were generated by exposure to an EGFR TKI, gefitinib, in vitro. Cell lines were characterised for their biological behaviour in vitro (using growth inhibition assays, flow cytometry, western blots, antibody arrays and/or immunoassays) and in vivo (using subcutaneous tumour xenografts). Sera from EGFR-treated and -untreated HNSCC patients were analysed by immunoassay.

RESULTS

Two independent sublines of CAL 27 and a PJ34 subline with acquired resistance to EGFR TKIs (gefitinib, erlotinib and afatinib) were developed. Resistant cells grew as highly aggressive xenografts leading to reduced host survival rates compared with EGFR-TKI sensitive cells. This suggested a link between resistance in vitro and poor prognosis in vivo. A significant upregulation of proteins linked to tumour angiogenesis and invasion was identified in resistant cells. This 'resistance-associated protein signature' (RAPS) was detected in the sera of a small cohort of HNSCC patients and was associated with reduced survival.

CONCLUSION

We have identified a protein signature associated with EGFR-TKI resistance that may also be linked to poor prognosis and warrants further investigation as a potential clinical biomarker.

Molecular phenotype predicts sensitivity of squamous cell carcinoma of the head and neck to epidermal growth factor receptor inhibition

Despite nearly universal expression of the wild-type epidermal growth factor receptor (EGFR) and reproducible activity of EGFR inhibitors in patients with squamous cell carcinoma of the head and neck (SCCHN), the majority of patients will not have objective responses. The mechanisms of this intrinsic resistance are not well established. We hypothesized that sensitivity to EGFR inhibitors can be predicted based on the inhibitors' effects on downstream signaling. Cell viability assays were used to assess sensitivity to the EGFR inhibitor gefitinib (ZD1839) in 8 SCCHN cell lines. Fluorescence in-situ hybridization showed the two most sensitive lines to be highly gene-amplified for EGFR. Western blotting confirmed that phosphoEGFR was inhibited at low concentrations of gefitinib in all lines tested. Phosphorylation of downstream signaling protein AKT was inhibited in sensitive lines while inhibition of phosphoERK displayed no relationship to gefitinib efficacy. Phosphatase and tensin homolog (PTEN) expression was evident in all cell lines. Activating PIK3CA mutations were found in two resistant cell lines where pAKT was not inhibited by gefitinib. In resistant cell lines harboring PIK3CA mutations, a PI3K inhibitor, LY294002, or AKT siRNA reduced cell viability with an additive effect demonstrated in combination with gefitinib. Additionally, LY294002 alone and in combination with gefitinib, was effective at treating PIK3CA mutated tumors xenografted into nude mice. Taken together this suggests that constitutively active AKT is a mechanism of intrinsic gefitinib resistance in SCCHN. This resistance can be overcome through targeting of the PI3K/AKT pathway in combination with EGFR inhibition.

Reovirus exerts potent oncolytic effects in head and neck cancer cell lines that are independent of signalling in the EGFR pathway

Background

Reovirus exploits aberrant signalling downstream of Ras to mediate tumor-specific oncolysis. Since ~90% squamous cell carcinomas of the head and neck (SCCHN) over-express EGFR and SCCHN cell lines are sensitive to oncolytic reovirus, we conducted a detailed analysis of the effects of reovirus in 15 head and neck cancer cell lines. Both pre- and post-entry events were studied in an attempt to define biomarkers predictive of sensitivity/resistance to reovirus. In particular, we analysed the role of EGFR/Ras signalling in determining virus-mediated cytotoxicity in SCCHN.

Methods

To test whether EGFR pathway activity was predictive of increased sensitivity to reovirus, correlative analyses between reoviral IC50 by MTT assay and EGFR levels by western blot and FACS were conducted. Inhibition or stimulation of EGFR signalling were analysed for their effect on reoviral oncolysis by MTT assay, and viral growth by TCID50 assay. We next analysed the effects of inhibiting signalling downstream of Ras, by specific inhibitors of p38MAPK, PI3-K or MEK, on reoviral killing examined by MTT assay. The role of PKR in reoviral killing was also determined by blockade of PKR using 2-aminopurine and assaying for cell survival by MTT assay. The apoptotic response of SCCHN to reovirus was examined by western blot analysis of caspase 3 cleavage.

Results

Correlative analyses between reoviral sensitivity and EGFR levels revealed no association. Intermediate sub-viral and core particles showed the same infectivity/cytotoxicity as intact reovirus. Therefore, sensitivity was not determined by cell entry. In 4 cell lines, oncolysis and viral growth were both unaffected by inhibition or stimulation of EGFR signalling. Inhibition of signalling downstream of Ras did not abrogate reoviral oncolysis and, in addition, modulation of PKR using 2-aminopurine did not alter reovirus sensitivity in resistant cell lines. Caspase 3 cleavage was not detected in infected cells and oncolysis was observed in pan-caspase inhibited cells.

Conclusions

In summary, reovirus is potently oncolytic in a broad panel of SCCHN cell lines. Attempts to define sensitivity/resistance by analysis of the EGFR/Ras/MAPK pathway have failed to provide a clear predictive biomarker of response. Further analysis of material from in vitro and clinical studies is ongoing in an attempt to shed further light on this issue.

Optical molecular imaging of multiple biomarkers of epithelial neoplasia: epidermal growth factor receptor expression and metabolic activity in oral mucosa

Biomarkers of cancer can indicate the presence of disease and serve as therapeutic targets. Our goal is to develop an optical imaging approach using molecularly targeted contrast agents to assess several centimeters of mucosal surface for mapping expression of multiple biomarkers simultaneously with high spatial resolution. The ability to image biomarker expression level and heterogeneity in vivo would be extremely useful for clinical cancer research, patient selection of personalized medicine, and monitoring therapy. In this proof-of-concept ex vivo study, we examined correlation of neoplasia with two clinically relevant biomarkers: epidermal growth factor receptor (EGFR) and metabolic activity. Two hundred eighty-six unique locations in nine samples of freshly resected oral mucosa were imaged after topically applying optical imaging agents EGF-Alexa 647 (to target EGFR) and 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (to target metabolic activity). Quantitative features were calculated from resulting fluorescence images and compared with tissue histopathology maps. The EGF-Alexa 647 signal correlated well with EGFR expression as indicated by immunohistochemistry. A classification algorithm for presence of neoplasia based on the signal from both contrast agents resulted in an area under the curve of 0.83. Regions with a posterior probability from 0.80 to 1.00 contained more than 50% neoplasia 99% (84/85) of the time. This study demonstrates a proof-of-concept of how noninvasive optical imaging can be used as a tool to study expression levels of multiple biomarkers and their heterogeneity across a large mucosal surface and how biomarker characteristics correlate with presence of neoplasia. Applications of this approach include predicting regions with the highest likelihood of disease, elucidating the role of biomarker heterogeneity in cancer biology, and identifying patients who will respond to targeted therapy.

Activation of the insulin-like growth factor-1 receptor induces resistance to epidermal growth factor receptor antagonism in head and neck squamous carcinoma cells

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) have poor efficacy in head and neck squamous carcinoma cells (HNSCC). Because the IGF-1 receptor (IGF1R) generates potent prosurvival signals and has been implicated in therapeutic resistance, its ability to induce resistance to EGFR-TKIs was studied in vitro. Five HNSCC cell lines showed reduced sensitivity to the EGFR-TKI gefitinib when the IGF1R was activated. In SCC-25 and Cal27 cells, gefitinib inhibited basal and EGF-stimulated EGFR, extracellular signal-regulated kinase (Erk), and Akt phosphorylation and reduced cell number. This correlated with initiation of apoptosis based on a 4-fold increase in PARP cleavage and a 2.5-fold increase in Annexin V positivity. The apoptotic response and reduction in cell number were blocked by IGF1R activation, which resulted in phosphorylation of both Erk and Akt. In both the cell lines, IGF1R-induced Erk, but not Akt, activation was eliminated by gefitinib. IGF1R-induced gefitinib resistance was unaffected by MAP/Erk kinase inhibition with U0126 but was partially impaired by inhibition of phosphoinositide-3-kinase with LY294002. The IGF1R-TKI PQ401 inhibited growth of SCC-25 and Cal27 cells alone and also acted synergistically with gefitinib. Thus, the IGF1R can make HNSCC cells resistant to EGFR-TKI treatment via a prosurvival mechanism. Of the 8 HNSCC tumor samples studied, all samples expressed the IGF1R and 5 showed detectable IGF1R phosphorylation, suggesting that this receptor may be relevant in vivo, and thus, combined EGFR/IGF1R inhibition may be necessary in some patients for effective targeted molecular therapy.

Relationship between epidermal growth factor receptor gene copy number and protein expression in oral cavity squamous cell carcinoma

This study was designed to explore the relationship between epidermal growth factor receptor (EGFR) copy number and EGFR protein expression in oral cavity squamous cell carcinoma (OSCCs) in Taiwan. A total of 160 oral cavity squamous cell carcinomas were examined for EGFR protein overexpression using immunohistochemistry and for copy number using a fluorescence in situ hybridization (FISH) assay. Overexpression and increased gene copy numbers of EGFR were found in 75 (46.88%) and 50 (31.25%) cases, respectively. The concordance rate for EGFR gene amplification and protein overexpression was 100%. EGFR overexpression was associated with a poor prognosis both in terms of disease-free survival (DFS) and overall survival (OS). On the other hand, the association between an increase in EGFR gene copies and DFS or OS was insignificant. This was despite the observed significant associations between gene copy number and tumor stage, depth of tumor invasion, lymph node metastasis, bone invasion and perineural invasion. EGFR protein overexpression is closely related to EGFR copy number. Standard methodological and interpretation criteria need to be established that allows EGFR copy number combined with EGFR protein expression to be determined in a manner that allows individualized EGFR targeted therapy in OSCC patients.

The multiple roles of amphiregulin in human cancer

Amphiregulin (AREG) is one of the ligands of the epidermal growth factor receptor (EGFR). AREG plays a central role in mammary gland development and branching morphogenesis in organs and is expressed both in physiological and in cancerous tissues. Various studies have highlighted the functional role of AREG in several aspects of tumorigenesis, including self-sufficiency in generating growth signals, limitless replicative potential, tissue invasion and metastasis, angiogenesis, and resistance to apoptosis. The oncogenic activity of AREG has already been described in the most common human epithelial malignancies, such as lung, breast, colorectal, ovary and prostate carcinomas, as well as in some hematological and mesenchymal cancers. Furthermore, AREG is also involved in resistance to several cancer treatments. In this review, we describe the various roles of AREG in oncogenesis and discuss its translational potential, such as the development of anti-AREG treatments, based on AREG activity. In the last decade, independent groups have reported successful but sometimes contradictory results in relation to the potential of AREG to serve as a prognostic and/or predictive marker for oncology, especially with regard to anti-EGFR therapies. Thus, we also discuss the potential usefulness of using AREG as a therapeutic target and validated biomarker for predicting cancer outcomes or treatment efficacy.

Small molecule inhibitors of the host cell COX/AREG/EGFR/ERK pathway attenuate cytomegalovirus-induced pathogenesis

As with other herpesviruses, human cytomegalovirus (hCMV) has the ability to establish lifelong persistence and latent infection following primary exposure, salivary glands (SMGs) being the primary site of both. In the immunocompromised patient, hCMV is a common cause of opportunistic infections, and subsequent morbidity and mortality. Elucidating the molecular pathogenesis of CMV-induced disease is critical to the development of more effective and safer drug therapies. In the present study, we used a novel mouse postnatal SMG organ culture model of mCMV-induced dysplasia to investigate a candidate signaling network suggested by our prior studies (COX-2/AREG/EGFR/ERK). The objective was to employ small molecule inhibitors to target several key steps in the autocrine loop, and in this way ameliorate pathology. Our results indicate that upregulation of ERK phosphorylation is necessary for initial mCMV-induced pathogenesis, and that ErbB receptor family phosphorylation and downstream signaling are highly relevant targets for drug discovery.

A prognostic multigene classifier for squamous cell carcinomas of the larynx

Survival after diagnosis of laryngeal cancer has not improved over the last 20 years. Selection of patients for radio- and chemotherapy or surgery or follow-up strategies based on a prognostic classifier could improve survival without unduly extending radical surgery. We performed microarray gene expression analysis and developed a four-gene classifier for laryngeal cancer using Prediction Analysis of Microarray and leave-one-out cross validation. A four-gene classifier containing the non-coding gene H19, the histone HIST1H3F and the two small nucleolar RNAs, SNORA16A and SNORD14C was developed that assigns cases to low and high risk classes. The high risk class has a relative risk of 6.5 (CI=1.817-23.258, Fisher exact test p<0.0001). The maternally imprinted gene H19 is the top classifier gene.

Clinical impact of amphiregulin expression in patients with epidermal growth factor receptor (EGFR) wild-type nonsmall cell lung cancer treated with EGFR-tyrosine kinase inhibitors

BACKGROUND

In patients with nonsmall cell lung cancer (NSCLC), several studies have demonstrated a positive correlation between somatic mutation in the epidermal growth factor receptor (EGFR) tyrosine kinase domain and clinical outcomes with the use of EGFR tyrosine kinase inhibitors (TKIs). However, some patients with wild-type (WT) EGFR also responded to EGFR TKIs and remained stable. Recently, amphiregulin (AR) has been suggested as a predictive marker for EGFR TKIs in patients with WT EGFR-positive NSCLC. The objective of the current study was to evaluate the association between AR expression and the efficacy of using EGFR TKIs in the treatment of patients with WT EGFR-positive NSCLC.

METHODS

Seventy-three patients with WT EGFR-positive NSCLC received treatment with gefitinib or erlotinib between May 2005 and December 2008. AR expression was assessed by immunohistochemistry.

RESULTS

The clinical response to EGFR TKIs was reassessed for all patients as follows: 16 of 73 patients had a partial response (21.9%), 12 patients had stable disease (16.5%), and 45 patients had progressive disease (61.6%). AR expression was positive in 24 of 40 patients (60%). The ability to achieve disease control did not differ significantly between AR-positive patients and AR-negative patients (P = .188). At a median follow-up of 25.4 months (range, 10.5-53.3 months), progression-free survival was 8.1 weeks in AR-positive patients and 4 weeks in AR-negative patients (P = .025), and overall survival was significantly longer in AR-positive patients than in AR-negative patients (12.2 months vs 4.1 months; P = .001).

CONCLUSIONS

The current results suggested that patients with WT EGFR-positive NSCLC who have AR-positive tumors may benefit clinically from treatment with EGFR TKIs, indicating that AR expression may be a potential marker for the selection of EGFR-TKI treatment for patients with WT EGFR-positive NSCLC.

Association of epidermal growth factor receptor and mitogen-activated protein kinase with cystic neoplasms of the pancreas

The molecular pathobiology of pancreatic cystic neoplasms is poorly understood. The aim of this study was to know the involvement of epidermal growth factor receptor (EGFR) and its downstream targets in the serous cystic neoplasms and the mucinous cystic neoplasms of the pancreas. In a total of 72 pancreatic cystic neoplasms, including 39 serous cystic neoplasms and 33 mucinous cystic neoplasms, we examined the expression of native and phosphorylated EGFR, mitogen-activated protein kinase (MAPK), and AKT by immunohistochemistry and somatic mutations in EGFR, KRAS, BRAF, and PIK3CA, by direct sequencing. We also assessed the copy numbers of EGFR transcripts and the amplification of the EGFR gene in some of the samples. We found that EGFR, phosphorylated EGFR, MAPK, and phosphorylated MAPK were evidently expressed in 100, 54, 100, and 69% of the serous cystic neoplasms, and in 12%, none, 33, and 27% of the mucinous cystic neoplasms, respectively; the expression was significantly higher and more prevalent in the serous cystic neoplasms than in the mucinous cystic neoplasms. The expression of AKT and phosphorylated AKT was low in both the types of neoplasms. On average, EGFR transcripts in the serous cystic neoplasms and the mucinous cystic neoplasms increased 53.5- and 2.5-fold, respectively, as compared with that in normal tissues, with the increase in the former being significantly greater than that in the latter. Amplification of the EGFR gene was not detected in any of the examined serous cystic neoplasms. None of the tumors had mutations in any of the examined portions of the genes, except two mucinous cystic neoplasms with mutations in codon-12 of KRAS. These results indicate that EGFR and MAPK are actively involved in the pathobiology of serous cystic neoplasms and may therefore be potential diagnostic markers and therapeutic targets in patients with the above mentioned types of neoplasms.

Epidermal growth factor receptor expression and gene copy number in the risk of oral cancer

Leukoplakia is the most common premalignant lesion of the oral cavity. Epidermal growth factor receptor (EGFR) abnormalities are associated with oral tumorigenesis and progression. We hypothesized that EGFR expression and gene copy number changes are predictors of the risk of an oral premalignant lesion (OPL) progressing to oral squamous cell carcinoma (OSCC). A formalin-fixed, paraffin-embedded OPL biopsy specimen was collected from each of 162 patients in a randomized controlled clinical trial. We assessed EGFR expression by immunohistochemistry with two

METHODS

a semiquantitative analysis (145 evaluable specimens) and an automated quantitative analysis (127 evaluable specimens). EGFR gene copy number was assessed by fluorescence in situ hybridization (FISH) in a subset of 49 OPLs with high EGFR expression defined by the semiquantitative analysis. We analyzed EGFR abnormalities for associations with OSCC development. High EGFR expression occurred in 103 (71%) of the 145 OPLs and was associated with a nonsignificantly higher risk of OSCC (P = 0.10). Twenty (41%) of 49 OPLs assessed by FISH had an increased EGFR gene copy number (FISH-positive). Patients with FISH-positive lesions had a significantly higher incidence of OSCC than did patients with FISH-negative (a normal copy number) lesions (P = 0.0007). Of note, 10 of 11 OSCCs that developed at the site of the examined OPL were in the FISH-positive group, leaving only one FISH-negative OPL that did so (P < 0.0001). Our data indicate that an increased EGFR gene copy number is common in and associated with OSCC development in patients with OPLs expressing high EGFR, particularly OSCC developing at the site of a high-expression OPL; they also suggest that EGFR inhibitors may prevent oral cancer in patients with OPLs having an increased EGFR gene copy number.

Molecular diagnostics for head and neck pathology

Molecular diagnostic techniques are quickly finding a role in the detection and diagnosis of tumors, and in predicting their behavior. They may also prove useful in developing new therapeutic approaches to head and neck cancer. The surgeon working in the craniomaxillofacial region should have an understanding of these technologies, their availability in various settings, and how they affect various aspects of treatment, particularly in the detection and treatment of malignancies. This article offers an overview of recent advances in molecular diagnostic techniques, with their implications for diagnosis and management of head and neck tumors.

Pharmacogenomic discovery using cell-based models

Quantitative variation in response to drugs in human populations is multifactorial; genetic factors probably contribute to a significant extent. Identification of the genetic contribution to drug response typically comes from clinical observations and use of classic genetic tools. These clinical studies are limited by our inability to control environmental factors in vivo and the difficulty of manipulating the in vivo system to evaluate biological changes. Recent progress in dissecting genetic contribution to natural variation in drug response through the use of cell lines has been made and is the focus of this review. A general overview of current cell-based models used in pharmacogenomic discovery and validation is included. Discussion includes the current approach to translate findings generated from these cell-based models into the clinical arena and the use of cell lines for functional studies. Specific emphasis is given to recent advances emerging from cell line panels, including the International HapMap Project and the NCI60 cell panel. These panels provide a key resource of publicly available genotypic, expression, and phenotypic data while allowing researchers to generate their own data related to drug treatment to identify genetic variation of interest. Interindividual and interpopulation differences can be evaluated because human lymphoblastoid cell lines are available from major world populations of European, African, Chinese, and Japanese ancestry. The primary focus is recent progress in the pharmacogenomic discovery area through ex vivo models.

Building a better understanding of the intracellular tyrosine kinase PTK6 - BRK by BRK

Protein tyrosine kinase 6 (PTK6), also referred to as breast tumor kinase BRK, is a member of a distinct family of kinases that is evolutionarily related to the SRC family of tyrosine kinases. While not expressed in the normal mammary gland, PTK6 expression is detected in a large proportion of human mammary gland tumors. In breast tumor cells, PTK6 promotes growth factor signaling and cell migration. PTK6 expression is also increased in a number of other epithelial tumors, including ovarian and colon cancer. In contrast, PTK6 is expressed in diverse normal epithelia, including the linings of the gastrointestinal tract, skin and prostate, where its expression correlates with cell cycle exit and differentiation. Disruption of the mouse Ptk6 gene leads to increased growth and impaired differentiation in the small intestine that is accompanied by increased AKT and Wnt signaling. Following total body irradiation, PTK6 expression is induced in proliferating progenitor cells of the intestine, where it plays an essential role in DNA-damage induced apoptosis. A distinguishing feature of PTK6 is its flexibility in intracellular localization, due to a lack of amino-terminal myristoylation/palmitoylation. Recently a number of substrates of PTK6 have been identified, including nuclear RNA-binding proteins and transcription factors. We discuss PTK6 signaling, its apparent conflicting roles in cancer and normal epithelia, and its potential as a therapeutic target in epithelial cancers.

Restoration of BRAK / CXCL14 gene expression by gefitinib is associated with antitumor efficacy of the drug in head and neck squamous cell carcinoma

Clinical efficacy of gefitinib (ZD1839, Iressa), which is an inhibitor specific for epidermal growth factor (EGF) receptor tyrosine kinase, has been shown in non-small-cell lung carcinoma patients with EGF receptor mutations, so these mutations are useful marker(s) to find a responder for the drug. Recent studies have shown that the EGF receptor gene mutation is rare in squamous cell carcinoma in the esophageal and head and neck regions. We previously reported that the expression of the chemokine BRAK/CXCL14 in head and neck squamous cell carcinoma (HNSCC) cells was down-regulated by EGF treatment, and that forced expression of BRAK in tumor cells decreased the tumorigenicity of the cells in xenografts. Thus, we investigated the relationship between restoration of BRAK expression by gefitinib and the efficacy of the drug for tumor suppression. We found that EGF down-regulated BRAK expression through the MEK-extracellular signal regulated kinase pathway and that this down-regulated expression was restored by gefitinib in vitro. Oral administration of gefitinib significantly (P < 0.001) reduced tumor growth of xenografts of three HNSCC cell lines (HSC-2, HSC-3, and HSC-4), in female athymic nude mice, accompanied by an increase in BRAK expression specifically in tumor tissue. This tumor-suppressing effect of the drug was not observed in the case of BRAK non-expressing cells. Furthermore introduction of BRAK shRNA vector reduced both the expression levels of BRAK in HSC-3 cells and the antitumor efficacy of gefitinib in vivo. Our data showing an inverse relationship between BRAK expression levels in tumor cells and the tumor growth rate indicate that the gefitinib-induced increase in BRAK expression is beneficial for tumor suppression in vivo.