ERBB2 amplifications in esophageal adenocarcinoma

Cancer Risk in Barrett's Esophagus: A Clinical Review

Esophageal adenocarcinoma (EAC) is rapidly increasing in incidence and is associated with a poor prognosis. Barrett's esophagus (BE) is a known precursor of esophageal adenocarcinoma. This review aims to explore Barrett's esophagus, esophageal adenocarcinoma, and the progression from the former to the latter. An overview of the definition, diagnosis, epidemiology, and risk factors for both entities are presented, with special attention being given to the areas of debate in the literature. The progression from Barrett's esophagus to esophageal adenocarcinoma is reviewed and the relevant molecular pathways are discussed. The definition of Barrett's esophagus remains debated and without international consensus. This, alongside other factors, has made establishing the true prevalence of Barrett's esophagus challenging. The degree of dysplasia can be a histological challenge, but is necessary to guide clinical management. The progression of BE to EAC is likely driven by inflammatory pathways, pepsin exposure, upregulation of growth factor pathways, and mitochondrial changes. Surveillance is maintained through serial endoscopic evaluation, with shorter intervals recommended for high-risk features.

Pepsinogen/Proton Pump Co-Expression in Barrett's Esophageal Cells Induces Cancer-Associated Changes

EDUCATIONAL OBJECTIVE

At the conclusion of this presentation, participants should better understand the carcinogenic potential of pepsin and proton pump expression in Barrett's esophagus.

OBJECTIVE

Barrett's esophagus (BE) is a well-known risk factor for esophageal adenocarcinoma (EAC). Gastric H⁺ /K⁺ ATPase proton pump and pepsin expression has been demonstrated in some cases of BE; however, the contribution of local pepsin and proton pump expression to carcinogenesis is unknown. In this study, RNA sequencing was used to examine global transcriptomic changes in a BE cell line ectopically expressing pepsinogen and/or gastric H⁺ /K⁺ ATPase proton pumps.

STUDY DESIGN

In vitro translational.

METHODS

BAR-T, a human BE cell line devoid of expression of pepsinogen or proton pumps, was transduced by lentivirus-encoding pepsinogen (PGA5) and/or gastric proton pump subunits (ATP4A, ATP4B). Changes relative to the parental line were assessed by RNA sequencing.

RESULTS

Top canonical pathways associated with protein-coding genes differentially expressed in pepsinogen and/or proton pump expressing BAR-T cells included those involved in the tumor microenvironment and epithelial-mesenchymal transition. Top upstream regulators of coding transcripts included TGFB1 and ERBB2, which are associated with the pathogenesis and prognosis of BE and EAC. Top upstream regulators of noncoding transcripts included p300-CBP, I-BET-151, and CD93, which have previously described associations with EAC or carcinogenesis. The top associated disease of both coding and noncoding transcripts was cancer.

CONCLUSIONS

These data support the carcinogenic potential of pepsin and proton pump expression in BE and reveal molecular pathways affected by their expression. Further study is warranted to investigate the role of these pathways in carcinogenesis associated with BE.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:59-69, 2023.

Targeted imaging of esophageal adenocarcinoma with a near-infrared fluorescent peptide

BACKGROUND

Targeted optical imaging offers a noninvasive and accurate method for the early detection of gastrointestinal tumors, especially for flat appearances. In our previous study, a sequence of SNFYMPL (SNF) was identified as a specific peptide to bind to esophageal carcinoma using phage-display technology. This study aimed to evaluate the tumor-targeting efficacy of Cy5.5-conjugated SNF probe for imaging of esophageal carcinoma in vitro and in vivo.

METHODS

The SNF-Cy5.5 probe was synthesized and then identified using High Performance Liquid Chromatography (HPLC) and mass spectrometry (MS). Confocal fluorescence imaging and Flow cytometry analysis were performed to evaluate the binding specificity and the receptor binding affinity of SNF-Cy5.5 to OE33. In vivo imaging was performed to evaluate the targeting ability of SNF-Cy5.5 to esophageal carcinoma.

RESULTS

The confocal imaging and flow cytometry analysis showed that SNF-Cy5.5 bound specifically to the plasma membrane of OE33 cells with a high affinity. In vivo, for non-block group, SNF-Cy5.5 probe exhibited rapid OE33 tumor targeting during 24 h p.i. and excellent tumor-to-background contrast at 2 h p.i. For the block group, SNF-Cy5.5 was not observed in the mice after 4 h p.i. Ex vivo imaging also revealed that a higher fluorescent signal intensity value of the tumors was clearly observed in the non-block group than that in the block group (2.6 ± 0.32 × 10⁹ vs. 0.8 ± 0.08 × 10⁹, p < 0.05).

CONCLUSIONS

SNF-Cy5.5 was synthesized and characterized with a high efficiency and purity. The higher affinity, specificity, and tumor targeting efficacy of SNF-Cy5.5 were confirmed by in vitro and in vivo tests. SNF-Cy5.5 is a promising optical probe for the imaging of esophageal adenocarcinoma.

Repurposing of KLF5 activates a cell cycle signature during the progression from a precursor state to oesophageal adenocarcinoma

Oesophageal adenocarcinoma (OAC) is one of the most common causes of cancer deaths. Barrett's oesophagus (BO) is the only known precancerous precursor to OAC, but our understanding about the molecular events leading to OAC development is limited. Here, we have integrated gene expression and chromatin accessibility profiles of human biopsies and identified a strong cell cycle gene expression signature in OAC compared to BO. Through analysing associated chromatin accessibility changes, we have implicated the transcription factor KLF5 in the transition from BO to OAC. Importantly, we show that KLF5 expression is unchanged during this transition, but instead, KLF5 is redistributed across chromatin to directly regulate cell cycle genes specifically in OAC cells. This new KLF5 target gene programme has potential prognostic significance as high levels correlate with poorer patient survival. Thus, the repurposing of KLF5 for novel regulatory activity in OAC provides new insights into the mechanisms behind disease progression.

LJELSR: A Strengthened Version of JELSR for Feature Selection and Clustering

Feature selection and sample clustering play an important role in bioinformatics. Traditional feature selection methods separate sparse regression and embedding learning. Later, to effectively identify the significant features of the genomic data, Joint Embedding Learning and Sparse Regression (JELSR) is proposed. However, since there are many redundancy and noise values in genomic data, the sparseness of this method is far from enough. In this paper, we propose a strengthened version of JELSR by adding the L₁-norm constraint on the regularization term based on a previous model, and call it LJELSR, to further improve the sparseness of the method. Then, we provide a new iterative algorithm to obtain the convergence solution. The experimental results show that our method achieves a state-of-the-art level both in identifying differentially expressed genes and sample clustering on different genomic data compared to previous methods. Additionally, the selected differentially expressed genes may be of great value in medical research.

Her2-Targeted Therapy Induces Autophagy in Esophageal Adenocarcinoma Cells

Esophageal adenocarcinoma (EAC) is a highly lethal cancer type with an overall poor survival rate. Twenty to thirty percent of EAC overexpress the human epidermal growth factor receptor 2 (Her2), a transmembrane receptor tyrosine kinase promoting cell growth and proliferation. Patients with Her2 overexpressing breast and gastroesophageal cancer may benefit from Her2 inhibitors. Therapy resistance, however, is well documented. Since autophagy, a lysosome-dependent catabolic process, is implicated in cancer resistance mechanisms, we tested whether autophagy modulation influences Her2 inhibitor sensitivity in EAC. Her2-positive OE19 EAC cells showed an induction in autophagic flux upon treatment with the small molecule Her2 inhibitor Lapatinib. Newly generated Lapatinib-resistant OE19 (OE19 LR) cells showed increased basal autophagic flux compared to parental OE19 (OE19 P) cells. Based on these results, we tested if combining Lapatinib with autophagy inhibitors might be beneficial. OE19 P showed significantly reduced cell viability upon double treatment, while OE19 LR were already sensitive to autophagy inhibition alone. Additionally, Her2 status and autophagy marker expression (LC3B and p62) were investigated in a treatment-naïve EAC patient cohort (n = 112) using immunohistochemistry. Here, no significant correlation between Her2 status and expression of LC3B and p62 was found. Our data show that resistance to Her2-directed therapy is associated with a higher basal autophagy level, which is not per se associated with Her2 status. Therefore, we propose that autophagy may contribute to acquired resistance to Her2-targeted therapy in EAC, and that combining Her2 and autophagy inhibition might be beneficial for EAC patients.

Multiplexed Targeting of Barrett's Neoplasia with a Heterobivalent Ligand: Imaging Study on Mouse Xenograft in Vivo and Human Specimens ex Vivo

Esophageal adenocarcinoma (EAC) is a molecularly heterogeneous disease that is rising rapidly in incidence and has poor prognosis. We developed a heterobivalent peptide to target detection of early Barrett's neoplasia by combining monomer heptapeptides specific for either EGFR or ErbB2 in a heterodimer configuration. The structure of a triethylene glycol linker was optimized to maximize binding interactions to the surface receptors on cells. The Cy5.5-labeled heterodimer QRH*-KSP*-E3-Cy5.5 demonstrated specific binding to each target and showed 3-fold greater fluorescence intensity and 2-fold higher affinity compared with those of either monomer alone. Peak uptake in xenograft tumors was observed at 2 h postinjection with systemic clearance by ∼24 h in vivo. Furthermore, ligand binding was evaluated on human esophageal specimens ex vivo, and 88% sensitivity and 87% specificity were found for the detection of either high-grade dysplasia (HGD) or EAC. This peptide heterodimer shows promise for targeted detection of early Barrett's neoplasia in clinical study.

HER2 Amplification in Tumors Activates PI3K/Akt Signaling Independent of HER3

Current evidence suggests that HER2-driven tumorigenesis requires HER3. This is likely due to the unique ability of HER3 to activate PI3K/Akt pathway signaling, which is not directly accessible to HER2. By genetic elimination of HER3 or shRNA knockdown of HER3 in HER2-amplified cancer cells, we find residual HER2-driven activation of PI3K/Akt pathway signaling that is driven by HER2 through direct and indirect mechanisms. Indirect mechanisms involved second messenger pathways, including Ras or Grb2. Direct binding of HER2 to PI3K occurred through p-Tyr1139, which has a weak affinity for PI3K but becomes significant at very high expression and phosphorylation. Mutation of Y1139 impaired the tumorigenic competency of HER2. Total elimination of HER3 expression in HCC1569 HER2-amplified cancer cells significantly impaired tumorigenicity only transiently, overcome by subsequent increases in HER2 expression and phosphorylation with binding and activation of PI3K. In contrast to activation of oncogenes by mutation, activation by overexpression was quantitative in nature: weak intrinsic activities were strengthened by overexpression, with additional gains observed through further increases in expression. Collectively, these data show that progressive functional gains by HER2 can increase its repertoire of activities such as the activation of PI3K and overcome its dependency on HER3.Significance: The intrinsic ability of HER2 to activate PI3K correlates with increased HER2 expression and can supplant the dependency upon HER3 for growth in HER2-amplified cancers. Cancer Res; 78(13); 3645-58. ©2018 AACR.

Acquired savolitinib resistance in non-small cell lung cancer arises via multiple mechanisms that converge on MET-independent mTOR and MYC activation

Lung cancer is the most common cause of cancer death globally with a significant, unmet need for more efficacious treatments. The receptor tyrosine kinase MET has been implicated as an oncogene in numerous cancer subtypes, including non-small cell lung cancer (NSCLC). Here we explore the therapeutic potential of savolitinib (volitinib, AZD6094, HMPL-504), a potent and selective MET inhibitor, in NSCLC. In vitro, savolitinib inhibits MET phosphorylation with nanomolar potency, which correlates with blockade of PI3K/AKT and MAPK signaling as well as MYC down-regulation. In vivo, savolitinib causes inhibition of these pathways and significantly decreases growth of MET-dependent xenografts. To understand resistance mechanisms, we generated savolitinib resistance in MET-amplified NSCLC cell lines and analyzed individual clones. We found that upregulation of MYC and constitutive mTOR pathway activation is a conserved feature of resistant clones that can be overcome by knockdown of MYC or dual mTORC1/2 inhibition. Lastly, we demonstrate that mechanisms of resistance are heterogeneous, arising via a switch to EGFR dependence or by a requirement for PIM signaling. This work demonstrates the efficacy of savolitinib in NSCLC and characterizes acquired resistance, identifying both known and novel mechanisms that may inform combination strategies in the clinic.

Integrated Proteomic and Genomic Analysis of Gastric Cancer Patient Tissues

V-erb-b2 erythroblastic leukemia viral oncogene homologue 2, known as ERBB2, is an important oncogene in the development of certain cancers. It can form a heterodimer with other epidermal growth factor receptor family members and activate kinase-mediated downstream signaling pathways. ERBB2 gene is located on chromosome 17 and is amplified in a subset of cancers, such as breast, gastric, and colon cancer. Of particular interest to the Chromosome-Centric Human Proteome Project (C-HPP) initiative is the amplification mechanism that typically results in overexpression of a set of genes adjacent to ERBB2, which provides evidence of a linkage between gene location and expression. In this report we studied patient samples from ERBB2-positive together with adjacent control nontumor tissues. In addition, non-ERBB2-expressing patient samples were selected as comparison to study the effect of expression of this oncogene. We detected 196 proteins in ERBB2-positive patient tumor samples that had minimal overlap (29 proteins) with the non-ERBB2 tumor samples. Interaction and pathway analysis identified extracellular signal regulated kinase (ERK) cascade and actin polymerization and actinmyosin assembly contraction as pathways of importance in ERBB2+ and ERBB2- gastric cancer samples, respectively. The raw data files are deposited at ProteomeXchange (identifier: PXD002674) as well as GPMDB.

[Long-term outcome of neoadjuvant radiochemotherapy followed by surgery for esophageal cancer: a single institution retrospective study of 102 patients]

PURPOSE AND OBJECTIVES

To report survival and morbidity of a large homogeneous cohort of patients with a locally advanced esophageal or cardia carcinoma and put in evidence predictive factors of locoregional control and survival.

PATIENTS AND METHODS

Hundred and two patients were treated at the university hospital of Tours between 1990 and 2010 and received neo-adjuvant chemoradiation therapy with external irradiation (40Gy-44Gy) and two courses of chemotherapy (5-fluoro-uracile and cisplatine). Esophagectomy associated with lymph node dissection was performed about ten weeks after the end of chemoradiation therapy.

RESULTS

The median follow-up was 22.4 months [6-185 months]. The overall survival rates at 2 and 5years were 53% and 27%, respectively. The median overall survival was estimated at 27months. The overall 2-year survival between patients "responders" and patients "non-responders" was 67% vs 26%, respectively (P<0.0001). In case of histological response, there was a benefit in terms of overall survival (P<0.0001), locoregional control (P<0.0036) and disease-free survival (P<0.001). Overall survival at 2years was 64% for ypN0 group vs 32% for ypN1 group (P<0.0001). The median survival was estimated at 37months against 15months in the absence of lymph node involvement (P<0.0001).

CONCLUSION

Our results in terms of survival, tolerance and morbidity and mortality were comparable to those in the literature. Complete histological response of lymph node was associated with an improvement of local control, disease-free survival and overall survival.

Translational research on esophageal adenocarcinoma: from cell line to clinic

Human esophageal adenocarcinoma (EAC) cell lines have made a substantial contribution to elucidating mechanisms of carcinogenesis and drug discovery. Model research on EAC relies almost entirely on a relatively small set of established tumor cell lines because appropriate animal models are lacking. Nowadays, more than 20% of all fundamental translational research studies regarding EAC are partially or entirely based on these cell lines. The ready availability of these cell lines to investigators worldwide have resulted in more than 250 publications, including many examples of important biomedical discoveries. The high genomic similarities (but certainly not completely identical) between the EAC cell lines and their original tumors provide rational for their use. Recently, in a collaborative effort all available EAC cell lines have been verified resulting in the establishment of a reliable panel of 10 EAC cell lines. It could be expected that the value of these cell lines increases as unlimited source of tumor material because new biomedical techniques require more tumor cells and the supply of viable tumor cells is diminishing because of neoadjuvant chemo(radio)therapy of patients with EAC. Here, we review the history of the EAC cell lines and their utility in translational research and biomedical discovery.

Constitutive ERK1/2 activation contributes to production of double minute chromosomes in tumour cells

Double minute chromosomes (DMs) are extrachromosomal cytogenetic structures found in tumour cells. As hallmarks of gene amplification, DMs often carry oncogenes and drug-resistance genes and play important roles in malignant tumour progression and drug resistance. The mitogen-activated protein kinase (MAPK) signalling pathway is frequently dysregulated in human malignant tumours, which induces genomic instability, but it remains unclear whether a close relationship exists between MAPK signalling and DMs. In the present study, we focused on three major components of MAPK signalling, ERK1/2, JNK1/2/3 and p38, to investigate the relationship between MAPK and DM production in tumour cells. We found that the constitutive phosphorylation of ERK1/2, but not JNK1/2/3 and p38, was closely associated with DMs in tumour cells. Inhibition of ERK1/2 activation in DM-containing and ERK1/2 constitutively phosphorylated tumour cells was able to markedly decrease the number of DMs, as well as the degree of amplification and expression of DM-carried genes. The mechanism was found to be an increasing tendency of DM DNA to break, become enveloped into micronuclei (MNs) and excluded from the tumour cells during the S/G₂ phases of the cell cycle, events that accompanied the reversion of malignant behaviour. Our study reveals a linkage between ERK1/2 activation and DM stability in tumour cells.

How a replication origin and matrix attachment region accelerate gene amplification under replication stress in mammalian cells

The gene amplification plays a critical role in the malignant transformation of mammalian cells. The most widespread method for amplifying a target gene in cell culture is the use of methotrexate (Mtx) treatment to amplify dihydrofolate reductase (Dhfr). Whereas, we found that a plasmid bearing both a mammalian origin of replication (initiation region; IR) and a matrix attachment region (MAR) was spontaneously amplified in mammalian cells. In this study, we attempted to uncover the underlying mechanism by which the IR/MAR sequence might accelerate Mtx induced Dhfr amplification. The plasmid containing the IR/MAR was extrachromosomally amplified, and then integrated at multiple chromosomal locations within individual cells, increasing the likelihood that the plasmid might be inserted into a chromosomal environment that permits high expression and further amplification. Efficient amplification of this plasmid alleviated the genotoxicity of Mtx. Clone-based cytogenetic and sequence analysis revealed that the plasmid was amplified in a chromosomal context by breakage-fusion-bridge cycles operating either at the plasmid repeat or at the flanking fragile site activated by Mtx. This mechanism explains how a circular molecule bearing IR/MAR sequences of chromosomal origin might be amplified under replication stress, and also provides insight into gene amplification in human cancer.

FGFR2 is amplified in the NCI-H716 colorectal cancer cell line and is required for growth and survival

Aberrant kinase activation resulting from mutation, amplification, or translocation can drive growth and survival in a subset of human cancer. FGFR2 is amplified in breast and gastric cancer, and we report here the first characterization of FGFR2 gene amplification in colorectal cancer in the NCI-H716 colorectal cancer cell line. FGFR2 is highly expressed and activated in NCI-H716 cells, and FGFR selective small molecule inhibitors or FGFR2 shRNA strongly inhibited cell viability in vitro, indicating “addiction” of NCI-H716 cells to FGFR2. NCI-H716 growth in a xenograft model was also inhibited by an FGFR small molecule inhibitor. FGFR2 was required for activation of multiple downstream signaling proteins including AKT, ERK, S6RP and NFKB. Inhibition of downstream kinases such as AKT or ERK alone had modest effects on proliferation, whereas combined inhibition of AKT and ERK signaling resulted in a loss of viability similar to FGFR2 inhibition. We identified elevated FGFR2 expression in a small subset of primary colorectal cancer, however FGFR2 amplification was not observed. Although FGFR2 amplification is not common in primary colon cancer or lymph node and liver metastases, other subsets of colorectal cancer such as ascites, from which the NCI-H716 cell line was derived, have yet to be tested. These results suggest that emerging FGFR inhibitor therapeutics may have efficacy in a subset of colon cancer driven by FGFR2 amplification.

Characterization of a novel tumorigenic esophageal adenocarcinoma cell line: OANC1

BACKGROUND

Esophageal adenocarcinoma (EAC) has a very high case fatality rate and is one of the fastest rising cancers worldwide. At the same time, research into EAC has been hampered by a relative lack of pre-clinical models, including representative cell lines.

AIM

The purpose of this study was to establish and characterize a new EAC cell line.

METHODS

Tumor cells were isolated from EAC tissue by enzymatic digestion. Origin of the cell line was confirmed by microsatellite based genotyping. A panel of cancer-related genes was screened for mutations by targeted deep sequencing, Sanger sequencing and high resolution melting.CDKN2A promoter methylation was assessed by methylation specific high resolution melting. HER2 amplification was assessed by fluorescent in situ hybridization. Immunohistochemistry was used to assess expression of markers in xenografts grown in SCID mice.

RESULTS

A novel EAC cell line, OANC1, was derived from a Barrett's-associated EAC. Microsatellite-based genotyping of OANC1 and patient DNA confirmed the origin of the cell line. Sequencing of OANC1 DNA identified homozygous TP53 missense (c.856G[A, p.E286K)and SMAD4 nonsense (c.1333C[T, p.R445X) mutations.OANC1 are tumorigenic when injected sub-cutaneously into SCID mice and xenografts were positive for columnar, glandular and intestinal epithelial markers commonly expressed in EAC. Xenografts exhibited strong p53 expression, consistent with a TP53 mutation. Some proteins, including p16, EGFR and b-catenin, had heterogeneous expression patterns across xenograft cross-sections, indicative of tumor heterogeneity.

CONCLUSIONS

OANC1 represents a valuable addition to the limited range of pre-clinical models for EAC. This new cell line will be a useful model system for researchers studying both basic and translational aspects of this disease.

Signaling pathways in the molecular pathogenesis of adenocarcinomas of the esophagus and gastroesophageal junction

Esophageal adenocarcinoma develops in response to severe gastroesophageal reflux disease through the precursor lesion Barrett esophagus, in which the normal squamous epithelium is replaced by a columnar lining. The incidence of esophageal adenocarcinoma in the United States has increased by over 600% in the past 40 years and the overall survival rate remains less than 20% in the community. This review highlights some of the signaling pathways for which there is some evidence of a role in the development of esophageal adenocarcinoma. An increasingly detailed understanding of the biology of this cancer has emerged recently, revealing that in addition to the well-recognized alterations in single genes such as p53, p16, APC, and telomerase, there are interactions between the components of the reflux fluid, the homeobox gene Cdx2, and the Wnt, Notch, and Hedgehog signaling pathways.

Mammalian interphase cdks: dispensable master regulators of the cell cycle

Cyclin-dependent kinases (Cdks) drive cell cycle progression in all eukaryotes. Yeasts have a single major Cdk that mediates distinct cell cycle transitions via association with different cyclins. The closest homolog in mammals, Cdk1, drives mitosis. Mammals have additional Cdks-Cdk2, Cdk4, and Cdk6-that represent the major Cdks activated during interphase (iCdks). A large body of evidence has accrued that suggests that activation of iCdks dictates progression though interphase. In apparent contradiction, deficiency in each individual iCdk, respectively, in knockout mice proved to be compatible with live birth and in some instances fertility. Moreover, murine embryos could be derived with Cdk1 as the only functional Cdk. Thus, none of the iCdks is strictly essential for mammalian cell cycle progression, raising the possibility that Cdk1 is the dominant regulator in interphase. However, an absence of iCdks has been accompanied by major shifts in cyclin association to Cdk1, suggesting gain in function. After considerable tweaking, a chemical genetic approach has recently been able to examine the impact of acute inhibition of Cdk2 activity without marked distortion of cyclin/Cdk complex formation. The results suggest that, when expressed at its normal levels, Cdk2 performs essential roles in driving human cells into S phase and maintaining genomic stability. These new findings appear to have restored order to the cell cycle field, bringing it full circle to the view that iCdks indeed play important roles. They also underscore the caveat in knockdown and knockout approaches that protein underexpression can significantly perturb a protein interaction network. We discuss the implications of the new synthesis for future cell cycle studies and anti-Cdk-based therapy of cancer and other diseases.

Bevacizumab-induced normalization of blood vessels in tumors hampers antibody uptake

In solid tumors, angiogenesis occurs in the setting of a defective vasculature and impaired lymphatic drainage that is associated with increased vascular permeability and enhanced tumor permeability. These universal aspects of the tumor microenvironment can have a marked influence on intratumoral drug delivery that may often be underappreciated. In this study, we investigated the effect of blood vessel normalization in tumors by the antiangiogenic drug bevacizumab on antibody uptake by tumors. In mouse xenograft models of human ovarian and esophageal cancer (SKOV-3 and OE19), we evaluated antibody uptake in tumors by positron emission tomographic imaging 24 and 144 hours after injection of (89)Zr-trastuzumab (SKOV-3 and OE19), (89)Zr-bevacizumab (SKOV-3), or (89)Zr-IgG (SKOV-3) before or after treatment with bevacizumab. Intratumor distribution was assessed by fluorescence microscopy along with mean vessel density (MVD) and vessel normalization. Notably, bevacizumab treatment decreased tumor uptake and intratumoral accumulation compared with baseline in the tumor models relative to controls. Bevacizumab treatment also reduced MVD in tumors and increased vessel pericyte coverage. These findings are clinically important, suggesting caution in designing combinatorial trials with therapeutic antibodies due to a possible reduction in tumoral accumulation that may be caused by bevacizumab cotreatment.

Clinicopathologic features and treatment outcomes of patients with human epidermal growth factor receptor 2-positive adenocarcinoma of the esophagus and gastroesophageal junction

Human epidermal growth factor receptor 2 (HER2) is overexpressed in 21% of gastric and 33% of gastroesophageal junction (GEJ) adenocarcinomas. Trastuzumab has been approved for metastatic HER2-positive gastric/GEJ cancer in combination with chemotherapy. This retrospective analysis was undertaken to better define the clinicopathologic features, treatment outcomes, and prognosis in patients with HER2-positive adenocarcinoma of the esophagus/GEJ. Pathologic specimens from 156 patients with adenocarcinoma of the esophagus/GEJ treated on clinical trials with chemoradiation and surgery were tested for HER2. Seventy-six patients also received 2 years of gefitinib. Baseline characteristics and treatment outcomes of the HER2-positive and negative patients were compared both in aggregate and separately for each of the two trials. Of 156 patients, 135 had sufficient pathologic material available for HER2 assessment. HER2 positivity was found in 23%; 28% with GEJ primaries and 15% with esophageal primaries (P= 0.10). There was no statistical difference in clinicopathologic features between HER2-positive and negative patients except HER2-negative tumors were more likely to be poorly differentiated (P < 0.001). Locoregional recurrence, distant metastatic recurrence, any recurrence, and overall survival were also statistically similar between the HER2-positive and the HER2-negative groups, in both the entire cohort and in the gefitinib-treated subset. Except for tumor differentiation, HER2-positive and negative patients with adenocarcinoma of the esophagus and GEJ do not differ in clinicopathologic characteristics and treatment outcomes. Given the demonstrated benefit of trastuzumab in HER2-positive gastric cancer and the similar incidence of HER2 overexpression in esophageal/GEJ adenocarcinoma, further evaluation of HER2-directed therapy in this disease seems indicated.

GERD-Barrett-Adenocarcinoma: Do We Have Suitable Prognostic and Predictive Molecular Markers?

Due to unfavorable lifestyle habits (unhealthy diet and tobacco abuse) the incidence of gastroesophageal reflux disease (GERD) in western countries is increasing. The GERD-Barrett-Adenocarcinoma sequence currently lacks well-defined diagnostic, progressive, predictive, and prognostic biomarkers (i) providing an appropriate screening method identifying the presence of the disease, (ii) estimating the risk of evolving cancer, that is, the progression from Barrett's esophagus (BE) to esophageal adenocarcinoma (EAC), (iii) predicting the response to therapy, and (iv) indicating an overall survival—prognosis for EAC patients. Based on histomorphological findings, detailed screening and therapeutic guidelines have been elaborated, although epidemiological studies could not support the postulated increasing progression rates of GERD to BE and EAC. Additionally, proposed predictive and prognostic markers are rather heterogeneous by nature, lack substantial proofs, and currently do not allow stratification of GERD patients for progression, outcome, and therapeutic effectiveness in clinical practice. The aim of this paper is to discuss the current knowledge regarding the GERD-BE-EAC sequence mainly focusing on the disputable and ambiguous status of proposed biomarkers to identify promising and reliable markers in order to provide more detailed insights into pathophysiological mechanisms and thus to improve prognostic and predictive therapeutic approaches.

The discovery of phenylbenzamide derivatives as Grb7-based antitumor agents

Grb7 is a non-catalytic protein, the overexpression of which has been associated with the proliferative and migratory potentials of cancer cells. Virtual screening strategies involving a shape-based similarity search, molecular docking, and 2D-similarity searches complemented by experimental binding studies (Thermofluor and isothermal titration calorimetry) resulted in the identification of nine novel phenylbenzamide-based antagonists of the Grb7 SH2 domain. Moderate binding affinities were observed, ranging from K(d)=32.3 μM for lead phenylbenzamide NSC 104999 (1) to K(d)=1.1 μM for a structurally related compound, NSC 57148 (2). Deconvolution of the affinity data into its components revealed differences in lead binding, from being entropy based (lead 1) to enthalpically driven (NSC 100874 (3), NSC 55158 (4), and compound 2). Finally, the lead compound 1 was found to decrease the growth of MDA-MB-468 breast cancer cells, with an IC(50) value of 39.9 μM. It is expected that these structures will serve as novel leads in the development of Grb7-based anticancer therapeutics.

Effective inhibition of metastases and primary tumor growth with CTCE-9908 in esophageal cancer

BACKGROUND

In spite of multimodular treatment, the therapeutic options for esophageal carcinoma are limited, and metastases remain the leading cause of tumor-related mortality. Expression of the chemokine receptor CXCR4 significantly correlates with poor survival rates in patients with esophageal carcinoma and is associated with lymph node and bone marrow metastases. The aim of this study was to evaluate the effect of the CXCR4 antagonist CTCE-9908 on metastatic homing and primary tumor growth in vitro and in vivo in an orthotopic xenograft model of esophageal cancer.

MATERIALS AND METHODS

OE19 cells were examined for stromal cell-derived factor 1 alpha-mediated migration under CTCE-9908 treatment. The CTCE-9908 treatment was further evaluated in an in vitro proliferation assay and orthotopic esophageal model, accompanied by magnetic resonance imaging. Tumor and metastases were immunohistochemically examined for CXCR4 expression.

RESULTS

CTCE-9908 has an inhibitory effect on stromal cell-derived factor 1 alpha-mediated migration and proliferation of OE19 cells. Treatment with CTCE-9908 in the orthotopic esophageal model leads to a reduction of metastatic spread and primary tumor growth. This was confirmed by magnetic resonsance imaging. Treatment with CTCE-9908 results in altered CXCR4 expression pattern exhibiting a high degree of variability.

CONCLUSION

CTCE-9908 effectively inhibits OE19 cell migration and proliferation in vitro, reduces metastases to lung, liver, and lymph nodes in vivo, and moreover leads to tumor growth reduction in an orthotopic model of esophageal carcinoma.

Cap-dependent mRNA translation and the ubiquitin-proteasome system cooperate to promote ERBB2-dependent esophageal cancer phenotype

Pathological post-transcriptional control of the proteome composition is a central feature of malignancy. Two steps in this pathway, eIF4F-driven cap-dependent mRNA translation and the ubiquitin-proteasome system (UPS), are deregulated in most if not all cancers. We tested a hypothesis that eIF4F is aberrantly activated in human esophageal adenocarcinoma (EAC) and requires elevated rates of protein turnover and proteolysis and thereby activated UPS for its pro-neoplastic function. Here, we show that 80% of tumors and cell lines featuring amplified ERBB2 display an aberrantly activated eIF4F. Direct genetic targeting of the eIF4F in ERBB2-amplified EAC cells with a constitutively active form of the eIF4F repressor 4E-BP1 decreased colony formation and proliferation and triggered apoptosis. In contrast, suppression of m-TOR-kinase activity towards 4E-BP1with rapamycin only modestly inhibited eIF4F-driven cap-dependent translation and EAC malignant phenotype; and promoted feedback activation of other cancer pathways. Our data show that co-treatment with 2 FDA-approved agents, the m-TOR inhibitor rapamycin and the proteasome inhibitor bortezomib, leads to strong synergistic growth-inhibitory effects. Moreover, direct targeting of eIF4F with constitutively active 4E-BP1 is significantly more potent in collaboration with bortezomib than rapamycin. These data support the hypothesis that a finely tuned balance between eIF4F-driven protein synthesis and proteasome-mediated protein degradation is required for the maintenance of ERBB2-mediated EAC malignant phenotype. Altogether, our study supports the development of pharmaceuticals to directly target eIF4F as most efficient strategy; and provides a clear rationale for the clinical evaluation of combination therapy with m-TOR inhibitors and bortezomib for EAC treatment.

Regulation of ERBB2 receptor by t-DARPP mediates trastuzumab resistance in human esophageal adenocarcinoma

Esophageal adenocarcinoma (EAC) is an aggressive malignancy with a poor outcome. Although targeting ERBB2 with trastuzumab has been evaluated in clinical trials, the molecular mechanisms of trastuzumab resistance remain uncharacterized in EAC. The dopamine and cyclic AMP-regulated phosphoprotein of MR 32000 (DARPP-32), also known as PPP1R1B, is located together with ERBB2 at the 17q12-q21 amplicon. We evaluated the expression of a transcript variant of DARPP-32 (t-DARPP) and ERBB2 in 141 primary tumors and investigated the role of t-DARPP in trastuzumab resistance using OE19 and OE33 EAC cell models. Overexpression of t-DARPP mRNA was detected in two-thirds of tumors with a correlation between ERBB2 and t-DARPP overexpression levels (r = 0.58, P = 0.003). Cell viability and clonogenic survival assays showed that t-DARPP increased survival by 40% in response to trastuzumab (P < 0.01). The Annexin-V staining and Western blot analysis indicated that t-DARPP effectively abrogated trastuzumab-induced apoptosis, inhibited cleavage of caspase-3, and blocked trastuzumab-induced dephosphorylation of ERBB2 and AKT proteins. The knockdown of endogenous t-DARPP reversed these effects and sensitized cells to trastuzumab (P < 0.01). The cycloheximide-based protein degradation analysis indicated that t-DARPP extended the half-life of ERBB2, explaining the increase in the basal levels of ERBB2, p-ERBB2(Y1248), and p-AKT(S473). Coimmunoprecipitation and Western blot analysis showed that t-DARPP associated with ERBB2 in a protein complex, and interfered with trastuzumab binding to the ERBB2 receptor. Using EAC-xenografted mouse model, t-DARPP enhanced tumor growth and rendered tumors unresponsive to trastuzumab. This study establishes t-DARPP as a mediator of trastuzumab resistance and underscores its potential importance in clinical trials of EAC.

Genomic organization and control of the grb7 gene family

Grb7 and their related family members Grb10 and Grb14 are adaptor proteins, which participate in the functionality of multiple signal transduction pathways under the control of a variety of activated tyrosine kinase receptors and other tyrosine-phosphorylated proteins. They are involved in the modulation of important cellular and organismal functions such as cell migration, cell proliferation, apoptosis, gene expression, protein degradation, protein phosphorylation, angiogenesis, embryonic development and metabolic control. In this short review we shall describe the organization of the genes encoding the Grb7 protein family, their transcriptional products and the regulatory mechanisms implicated in the control of their expression. Finally, the alterations found in these genes and the mechanisms affecting their expression under pathological conditions such as cancer, diabetes and some congenital disorders will be highlighted.

Trastuzumab has anti-metastatic and anti-angiogenic activity in a spontaneous metastasis xenograft model of esophageal adenocarcinoma

HER-2/neu over-expression occurs in 10-40% of patients with esophageal adenocarcinoma. Therefore, inhibitory effects of trastuzumab on proliferation, neoangiogenesis and metastatic spread of the esophageal adenocarcinoma cell line PT1590 were investigated (subcutaneous xenograft model). PT1590 revealed an amplified copy number of c-erbB2 and HER-2/neu over-expression occured in xenograft tumors and spontaneous lung metastases. PT1590 proliferation was significantly inhibited by trastuzumab in vitro. In vivo, tumor weight, volume, microvessel density and number of lung metastases decreased significantly after three weeks of treatment. These data suggest the importance of HER-2/neu for metastatic spread in esophageal adenocarcinoma and encourages clinical trials.

Her-2/neu gene amplification in esophageal adenocarcinoma and its influence on survival

BACKGROUND

HER-2/neu (c-erbB-2, HER2) gene amplification and protein overexpression have been associated with poor prognosis in several solid tumors, including breast and gastric cancer. Its incidence and significance in esophageal adenocarcinoma is unknown.

MATERIALS AND METHODS

Tissue microarrays were successfully constructed from 89 paraffin-embedded archival specimens of esophageal adenocarcinomas for HER2 gene amplification by silver-enhanced in situ hybridization (SISH). No patients had undergone neoadjuvant therapy. Protein overexpression was tested with immunohistochemistry (IHC) using automated immunostaining (Ventana Benchmark). Incidence of HER2 positivity, correlation to clinicopathological variables in esophageal cancer patients, and concordance between SISH and IHC were determined.

RESULTS

True HER2 gene amplification was detected in 14 esophageal cancer specimens (16%), and 92% of those with high-level HER2 amplification showed positive HER2 protein overexpression. No significant associations were found among gene amplification and clinicopathological factors. The 5-year survival rates were 57% for esophageal cancer patients with HER2 amplification compared with 32% without, but the difference in overall survival was not significant (P = .37). The correlation between SISH and IHC was statistically significant (P < .0001).

CONCLUSION

While molecular targeting may be possible for approximately 16% of esophageal adenocarcinoma patients, HER2 oncogene amplification did not influence survival in this study.

Esophageal adenocarcinoma: treatment modalities in the era of targeted therapy

Esophageal adenocarcinoma is an aggressive malignancy with a poor outcome, and its incidence continues to rise at an alarming rate. Current treatment strategies combining chemotherapy, radiation, and surgery are plagued with high rates of recurrence and metastasis. Multiple molecular pathways including the epidermal growth factor receptor, vascular endothelial growth factor, v-erb-b2 erythroblastic leukemia viral oncogene homolog (ERBB2), and Aurora kinase pathways are activated in many esophageal adenocarcinomas. In many cases, these pathways have critical roles in tumor progression. Research on the mechanisms by which these pathways contribute to disease progression has resulted in numerous biologic agents and small molecules with the potential to improve outcome. The promise of targeted therapy and personalized medicine in improving the clinical outcome is now closer than it has ever been.

Lack of HER2 overexpression and amplification in small intestinal adenocarcinoma

HER2 overexpression and amplification have been studied as a therapeutic and prognostic target in a number of human cancers, including esophageal, gastric, and colorectal adenocarcinomas. However, HER2 status has not been well investigated in primary small intestinal adenocarcinoma, probably because of its rarity. In this study, we conducted immunohistochemical analysis and fluorescence in situ hybridization (FISH) for HER2 on 49 primary nonampullar small intestinal adenocarcinomas. The results showed a complete lack of HER2 protein expression in 47 cases (96%) by immunohistochemical analysis. Only 2 cases (4%) showed a 1+ staining pattern. No tumors exhibited 2+ or 3+ HER2 immunoreactivity. By FISH, none of the tumors, including those with 1+ HER2 immunoreactivity, exhibited HER2 gene amplification. These observations demonstrate that HER2 protein overexpression and gene amplification are infrequent events, if they occur at all, in small intestinal adenocarcinoma. Thus, routine immunohistochemical and/or FISH testing for HER2 for potential targeted anti-HER2 therapy may not be beneficial for patients with primary small intestinal adenocarcinoma.

The intertwining of structure and function: proposed helix-swapping of the SH2 domain of Grb7, a regulatory protein implicated in cancer progression and inflammation

Grb7 is a multidomain intracellular signaling protein that links activated tyrosine kinases with downstream signaling targets. Best known for its regulatory role in cell migration and tumor metastasis, Grb7 also regulates inflammation by coupling NF-kappaB-inducing kinase with erbB/EGFR family receptors. The "adaptor" role of Grb7 in these processes depends upon binding to membrane-associated tyrosine kinases through its C-terminal SH2 domain. The Grb7-SH2 domain shares structural and functional similarity with the SH2 domain of Grb2, a constituent of the MAP kinase pathway. Both domains show unusual affinity for cyclic (beta-turn) ligands. The Grb2-SH2 domain also shows distinctive self-association behavior, forming intertwined ("swapped") dimers. While Grb7 and its SH2 domain are each known to dimerize, the mechanisms and functional significance of this self-association are incompletely understood. Additional residues in the Grb7-SH2 domain effectively lengthen its "EF loop" and render the domain a good candidate for swapped dimerization, through exchange of a C-terminal helix. We propose the existence of a swapped dimeric form of the Grb7-SH2 domain and offer a structural model derived through novel application of nuclear magnetic resonance-derived restraints.

Insulin-like growth factor-1 receptor as a novel prognostic marker and its implication as a cotarget in the treatment of human adenocarcinoma of the esophagus

Insulin-like growth factor-1 receptor (IGF-1R) and human epidermal growth factor receptor-2 (HER2) receptor expression has been found to be a key regulator of tumorigenesis. The purpose of our study was to establish the prognostic significance of IGF-1R in esophageal cancer and to determine the effect of IGF-1R and HER2 targeting with alpha-IR3 and Herceptin antibodies on the proliferation of esophageal cancer cells in vitro. IGF-1R expression and clinicopathological correlations were analyzed with a tissue microarray containing 234 esophageal cancer specimens (133 adenocarcinomas and 101 squamous cell carcinomas). Proliferation changes associated with Herceptin and alpha-IR3 blockage were evaluated with the unique human esophageal cancer cell lines Pt1590 and LN1590. IGF-1R and HER2 expression levels, activation and phosphorylation status of downstream signaling proteins involved in the activation pathways were analyzed by Western blotting. IGF-1R overexpression was detected in 121 (52%) of the 234 esophageal tumors examined. In the subgroup of 87 HER2-positive tumors, 93.1% showed concordant overexpression for IGF-1R. IGF-1R was identified as a variable associated with reduced overall survival for adenocarcinoma (p = 0.05), but not for squamous cell carcinoma. The combination of Herceptin and alpha-IR3 was more effective in inhibiting in vitro proliferation than treatment with either agent alone (p < 0.01). This was associated with a decrease in HER2 and IGF-1R protein levels and suppression of Akt- and MAP kinase phosphorylation. IGF-1R expression can be used as a novel prognostic marker for adenocarcinomas of the esophagus. Cotreatment with IGF-1R and HER2 antibodies might become a valuable and effective treatment option in esophageal adenocarcinoma.

Trastuzumab mediated T-cell response against HER-2/neu overexpressing esophageal adenocarcinoma depends on intact antigen processing machinery

Background

Esophageal adenocarcinoma (EAC) is a highly aggressive disease with poor prognosis, which frequently exhibits HER-2 gene amplification. Trastuzumab, the humanized antibody against HER-2, has potent growth inhibitory effects on HER-2 overexpressing cancers. One effect of trastuzumab is that it causes HER-2 receptor internalization and degradation, enhancing presentation of HER-2 epitopes on MHC-Class I molecules. This enhances the ability of HER-2 specific cytotoxic T lymphocytes (CTLs) to recognize and kill cancer cells. Novel strategies targeting the HER-2 receptor either directly by trastuzumab and/or indirectly by inducing a CTL response against HER-2 epitopes with, for instance, DC immunotherapy and consequently combining these strategies might prove to be very effective.

Methodology/Principal Findings

In this study we report that trastuzumab has potent growth inhibitory effects on two HER-2 overexpressing EAC cell lines OE33 and OE19. However, we found that trastuzumab and HER-2 specific CTLs act synergistically in inducing tumor lysis in OE33 but not in OE19. We discovered that in OE19 this deficient response is due to a down-regulation of the Transporter Associated with Antigen Processing-2 (TAP-2). TAP-2 is an important member of the Antigen Processing Machinery (APM), and is one of the essential elements for loading antigens on MHC class I molecules. Importantly, we demonstrated that by inducing re-expression of TAP-2 in OE19 with INF-γ treatment or by incubating the cells with INF-γ producing CTLs, the specific anti HER-2 CTL tumor lysis response and synergistic effect with trastuzumab can be restored.

Conclusion

An inefficient response of HER-2 overexpressing EAC to trastuzumab and/or DC immunotherapy can be due to a down-regulated TAP-2 expression and thus a deficient APM. Future studies combining trastuzumab with IFN-γ and/or immune-therapies inducing potent anti HER-2 CTL responses could lead to an effective combinatorial strategy for successful treatment of HER-2 overexpressing but APM defective cancers.

Chromosomal abnormalities and novel disease-related regions in progression from Barrett's esophagus to esophageal adenocarcinoma

Barrett's esophagus (BE) is a metaplastic condition caused by chronic gastroesophageal reflux which represents an early step in the development of esophageal adenocarcinoma (EAC). Single-nucleotide polymorphism microarray (SNP-chip) analysis is a novel, precise, high-throughput approach to examine genomic alterations in neoplasia. Using 250K SNP-chips, we examined the neoplastic progression of BE to EAC, studying 11 matched sample sets: 6 sets of normal esophagus (NE), BE and EAC, 4 of NE and BE and 1 of NE and EAC. Six (60%) of 10 total BE samples and 4 (57%) of 7 total EAC samples exhibited 1 or more genomic abnormalities comprising deletions, duplications, amplifications and copy-number-neutral loss of heterozygosity (CNN-LOH). Several shared abnormalities were identified, including chromosome 9p CNN-LOH [2 BE samples (20%)], deletion of CDKN2A [4 BE samples (40%)] and amplification of 17q12-21.2 involving the ERBB2, RARA and TOP2A genes [3.1 Mb, 2 EAC (29%)]. Interestingly, 1 BE sample contained a homozygous deletion spanning 9p22.3-p22.2 (1.2 Mb): this region harbors only 1 known gene, basonuclin 2 (BNC2). Real-time PCR analysis confirmed the deletion of this gene and decreased the expression of BNC2 mRNA in the BE sample. Furthermore, transfection and stable expression of BNC2 caused growth arrest of OE33 EAC cells, suggesting that BNC2 functions as a tumor suppressor gene in the esophagus and that deletion of this gene occurs during the development of EAC. Thus, this SNP-chip analysis has identified several early cytogenetic events and novel candidate cancer-related genes that are potentially involved in the evolution of BE to EAC.

Anti-ERBB2 sh-RNA suppress both cell growth and tumor growth in ERBB2-overexpressing upper gastrointestinal adenocarcinomas

INTRODUCTION

ERBB2 is overexpressed in 15-25% of upper gastrointestinal adenocarcinomas. We use a stable lentiviral shRNA model to demonstrate that ERBB2 suppression in upper gastrointestinal adenocarcinomas with documented ERBB2 amplification effectively decreases ERBB2 protein levels and decreases cell viability. Further, we evaluate tumor growth of cells treated with the ERBB2 shRNA.

METHODS

Three upper gastrointestinal adenocarcinoma cells lines with varying ERBB2 levels were treated with one of three separate lentiviral green fluorescent protein (GFP)-labeled ERBB2 shRNA vectors or a nonsilencing control shRNA vector for 6 h. Protein levels on day 6 and cell viability was evaluated on days 3-10. A xenograft in vivo experiment was performed using OE19 cells pretransduced with ERBB2 shRNA to evaluate tumor growth.

RESULTS

ERBB2 protein levels decreased by 80%. ERBB2 knockdown significantly decreased cell viability in cell lines with high ERBB2 levels. In vivo tumor growth was suppressed in ERBB2-shRNA-treated groups.

CONCLUSION

ERBB2 suppression based on a stable lentiviral shRNA transfection system effectively decreases cell viability in cell lines with amplification of ERBB2 as compared to cell lines without overexpression. ERBB2 knockdown significantly decreases tumor growth in vivo. ERBB2-directed therapy may be of benefit in the subset of patients with gastrointestinal adenocarcinomas exhibiting overamplification of ERBB2.

Tyrosine phosphorylation of growth factor receptor-bound protein-7 by focal adhesion kinase in the regulation of cell migration, proliferation, and tumorigenesis

We have previously reported that growth factor receptor-bound protein-7 (Grb7), an Src-homology 2 (SH2)-containing adaptor protein, enables interaction with focal adhesion kinase (FAK) to regulate cell migration in response to integrin activation. To further elucidate the signaling events mediated by FAK*Grb7 complexes in promoting cell migration and other cellular functions, we firstly examined the phosphorylated tyrosine site(s) of Grb7 by FAK using an in vivo mutagenesis. We found that FAK was capable of phosphorylating at least 2 of 12 tyrosine residues within Grb7, Tyr-188 and Tyr-338. Moreover, mutations converting the identified Tyr to Phe inhibited integrin-dependent cell migration as well as impaired cell proliferation but not survival compared with the wild-type control. Interestingly, the above inhibitory effects caused by the tyrosine phosphorylation-deficient mutants are probably attributed to their down-regulation of phospho-Tyr-397 of FAK, thereby implying a mechanism by competing with wild-type Grb7 for binding to FAK. Consequently, these tyrosine phosphorylation-deficient mutants evidently altered the phospho-Tyr-118 of paxillin and phosphorylation of ERK1/2 but less on phospho-Ser-473 of AKT, implying their involvement in the FAK*Grb7-mediated cellular functions. Additionally, we also illustrated that the formation of FAK*Grb7 complexes and Grb7 phosphorylation by FAK in an integrin-dependent manner were essential for cell migration, proliferation and anchorage-independent growth in A431 epidermal carcinoma cells, indicating the importance of FAK*Grb7 complexes in tumorigenesis. Our data provide a better understanding on the signal transduction event for FAK*Grb7-mediated cellular functions as well as to shed light on a potential therapeutic in cancers.

Peripheral position of CCND1 and HER-2/neu oncogenes within chromosome territories in esophageal and gastric cancers non-related to amplification and overexpression

Interphase chromosomes have been shown to occupy discrete regions of the nucleus denominated chromosome territories (CTs), their active genes being preferentially positioned on the surfaces of these CTs, where they are accessible to transcriptional machinery. By means of FISH (Fluorescence in situ Hybridization), we analyzed the CCND1 and HER-2/neu gene positions within the CTs and their relationship with gene amplification and protein over-expression in esophageal and gastric cancers. The CCND1 and HER-2/Neu genes were more often positioned at the periphery (mean frequency of 60%-83%) of the CTs in tumor tissues of the esophagus and stomach. Moreover, this positioning revealed no association with either gene amplification or the protein over-expression status of these genes, although, in esophageal carcinoma, Kappa statistics showed a moderate agreement between amplification of the CCND1 gene (Kappa = 0.400) and its location within the CT, as well as with over-expression of the corresponding protein (Kappa = 0.444). Thus, our results suggest that gene positioning in interphase chromosomes does not follow a definitive pattern neither does it depend only on gene transcriptional activity. Apparently, this positioning could be both gene- and tissue-specific, and depends on other factors acting together, such as dense-gene, chromosome size, chromatin structure, and the level and stability of its expression.

Esophageal cancer: current and emerging therapy modalities

During the last few years, there has been a gradual increase in treatment options for patients with esophageal malignancies. Several clinical studies have been performed, covering not only radiation and chemotherapy, but also the introduction of novel biological agents into the treatment arsenal. Patients with esophageal carcinoma are now offered second-line and sometimes even third-line treatments, and the number of research protocols is increasing. Despite the newly awakened interest in this malignancy, the overall 5-year survival rate has remained at approximately 10% since the 1980s. This review contains a compilation of available studies of esophageal malignancies and discusses current treatment options as well as newly developed therapies targeted at growth factor receptors.

G-rich oligonucleotides alter cell cycle progression and induce apoptosis specifically in OE19 esophageal tumor cells

Short synthetic oligonucleotides (ODNs) can be used to block cellular processes involved in cell growth and proliferation. Often acting as aptamers, these molecules interact with critical proteins that regulate the induction of apoptosis or necrosis. We have used a specialized class of ODNs that contain a monomeric sequence of guanosine to induce apoptosis specifically in the malignant esophageal cell line, OE19, in cell culture, and in a NODscid mouse model. OE19 cells were grown in culture and treated with a stable G-rich oligonucleotide (GRO). Cells were processed and apoptosis was measured by FACS analyses, caspase activity, and Hoescht staining. Circular dichroism (CD) was used to define the structure and stability of various GROs. The GRO works by first inducing retardation in the progression of the cell cycle and then by creating a sub-G1 population of apoptotic cells. The reaction is dose dependent, and appears to rely on the capacity of the G-rich ODN to adopt a G-quartet conformation. Apoptosis was measured by determining caspase 3/7 levels and by staining for nuclear fragmentation using the Hoechst dye. Importantly, nonmalignant esophageal cells or normal human lung fibroblasts are not impeded in their cell cycle progression when incubated with the G-rich ODNs. These results suggest that a selective killing of esophageal tumor cells is directed by G-rich ODNs. Selective killing was demonstrated in the unique activity of the GRO compared to other ODNs of different sequences as well as the response of oncogenic cells compared to nononcogenic cells.

Activation of growth factor receptors in esophageal cancer--implications for therapy

Esophageal cancer is a highly aggressive disease and is the seventh most common cause of cancer-related death in the western world. Worldwide, it ranks as the sixth most frequent cause of cancer death. Despite advances in surgical techniques and treatment, the prognosis of esophageal cancer remains poor, with very few long-term survivors. The need for novel strategies to detect esophageal cancer earlier and to improve current therapy is urgent. It is well established that growth factors and growth factor receptor-mediated signaling pathways are important components of the transformation process in many forms of cancer, including esophageal cancer. With the recent advances in drug development, there are emerging possibilities to use growth factor signal transduction pathways in targeted therapy. This review provides a summary of the role of growth factors and their receptors in esophageal cancer and discusses their potential roles as biomarkers and as targets in therapy.

IGFBP-3 and IGFBP-10 (CYR61) up-regulation during the development of Barrett's oesophagus and associated oesophageal adenocarcinoma: potential biomarkers of disease risk

Dys-regulation of the insulin-like growth factor (IGF) system increases the risk of a number of malignancies. The aim of this study was to investigate the role of members of the IGF binding protein (IGFBP) superfamily in the development of oesophageal adenocarcinoma (EAC) and their possible use as markers of disease risk. Expression of IGFBP-2, IGFBP-3, IGFBP-4, and IGFBP-10/CYR61 was assessed using Real-Time-polymerase chain reaction (PCR) and immunohistochemistry in oesophageal tissues from Barrett's oesophagus (BE) patients with and without associated EAC, and in control subjects. IGFBP-3, IGFBP-4, and IGFBP-10/CYR61 mRNA levels were up-regulated in Barrett's (n=17) and tumour tissue of EAC patients (n=18) compared with normal tissue of control subjects without BE or EAC (n=18) (p<0.001). Over-expression of IGFBP-3 and IGFBP-10/CYR61 proteins was observed in Barrett's, dysplastic and tumour tissue of EAC cases (n=47 for IGFBP-10; n=39 for IGFBP-3) compared with adjacent normal epithelium (p<0.050). Notably, IGFBP-3, IGFBP-4, and IGFBP-10/CYR61 expression in Barrett's tissue of EAC cases (n=17) was significantly (p<0.001) higher than in Barrett's tissue of BE patients with no sign of progression to cancer (n=15). Overall, the results suggest that members of the IGFBP superfamily are up-regulated during oesophageal carcinogenesis and merit further investigation as markers of EAC risk.

HER-2 overexpression (3+) in patients with squamous cell esophageal carcinoma correlates with poorer survival

The incidence of esophageal carcinoma is increasing worldwide. In Sweden, approximately 400 patients are diagnosed each year. The present study retrospectively investigates survival in 97 patients with esophageal carcinoma in regard to their HER-2 status as examined by immunohistochemistry (IHC) and chromogen in situ hybridization (CISH). Sixty-eight patients had localised disease and 29 patients had advanced disease. Seventy patients had squamous cell carcinoma, and nine of these patients (13%) had HER-2 overexpression (3+). Eight (30%) of 27 adenocarcinoma patients overexpressed (3+) HER-2. In patients overexpressing (3+) HER-2 a statistical trend towards poorer survival was observed (P = 0.057). In squamous cell carcinoma patients, HER-2 overexpression (3+) correlated with poorer survival (P = 0.035), whereas in adenocarcinoma patients, HER-2 status (3+) did not. HER-2 amplification according to CISH was present in five (two squamous cell carcinomas and three adenocarcinomas) out of 17 HER-2 overexpressing (3+) tumours. In conclusion, HER-2 overexpression (3+) seems to be associated with poorer survival in esophageal carcinomas, especially in patients with squamous cell esophageal carcinoma.

Alterations of the CCND1 and HER-2/neu (ERBB2) proteins in esophageal and gastric cancers

We evaluated the relationship of amplification and polysomy of both the CCND1 and the ERBB2 (alias HER-2/NEU) genes to the overexpression of their proteins in esophageal and gastric cancers and also their association with clinicopathological features. CCND1 gene amplification (45%) was more prevalent than polysomy (25%) in esophageal carcinoma, but the pattern observed was similar in gastric adenocarcinoma (10% amplification, 15% polysomy). For ERBB2, polysomy was a more frequent mechanism than amplification in both esophageal (32.5 vs. 7.5%) and gastric (15 vs. 5%) cancers. Overexpression of cyclin D1 protein was identified in 37.5% of the specimens of esophageal tumors and 35% of gastric tumors, and overexpression of Her-2/neu protein in 12.5 and 7.5%, respectively. The kappa-statistics revealed a fair agreement in both types of tumors only in overexpression and amplification of the CCND1 gene; the ERBB2 gene showed a fair agreement in amplification and polysomy and the level of protein expression in gastric adenocarcinoma. Thus, polysomy 17 could contribute to a high Her-2/neu protein level, at least in gastric cancer. Our data indicated an association with alcohol consumption and the CCND1 gene or protein levels, in both esophageal and gastric cancers.

Mechanism of Action of (−)-Epigallocatechin-3-Gallate: Auto-oxidation–Dependent Inactivation of Epidermal Growth Factor Receptor and Direct Effects on Growth Inhibition in Human Esophageal Cancer KYSE 150 Cells

(-)-Epigallocatechin-3-gallate (EGCG), the principal polyphenol in green tea, has been shown to inhibit the growth of many cancer cell lines and to suppress the phosphorylation of epidermal growth factor receptor (EGFR). We observed similar effects of EGCG in esophageal squamous cell carcinoma KYSE 150 cells and epidermoid squamous cell carcinoma A431 cells. Pretreatment of KYSE 150 cells with EGCG (20 micromol/L) for 0.5 to 24 hours in HAM's F12 and RPMI 1640 mixed medium at 37 degrees C, before the addition of EGF, resulted in a decreased level of phosphorylated EGFR (by 32-85%). Prolonged treatment with EGCG (8 or 24 hours) also decreased EGFR protein level (both by 80%). EGCG treatment for 24 hours also caused decreased signals of HER-2/neu in esophageal adenocarcinoma OE19 cells. These effects of EGCG were prevented or diminished by the addition of superoxide dismutase (SOD, 5 units/mL), or SOD plus catalase (30 units/mL), to the cell culture medium. A similar phenomenon on inactivation of EGFR was observed in A431 cells as well. Under culture conditions for KYSE 150 cells, EGCG was unstable, with a half-life of approximately 30 minutes; EGCG dimers and other oxidative products were formed. The presence of SOD in the culture medium stabilized EGCG and increased its half-life to longer than 24 hours and some EGCG epimerized to (+)-gallocatechin-3-gallate. A mechanism of superoxide radical-mediated dimerization of EGCG and H2O2 formation is proposed. The stabilization of EGCG by SOD in the culture medium potentiated the activity of EGCG in inhibiting KYSE 150 cell growth. The results suggest that in cell culture conditions, the auto-oxidation of EGCG leads to EGFR inactivation, but the inhibition of cell growth is due to other mechanisms. It remains to be determined whether the presently observed auto-oxidation of EGCG occurs in vivo. In future studies of EGCG and other polyphenolic compounds in cell culture, SOD may be added to stabilize EGCG and to avoid possible artifacts.