Targeting the epidermal growth factor receptor by erlotinib (Tarceva) for the treatment of esophageal cancer

Statistical inference with a manifold-constrained RNA velocity model uncovers cell cycle speed modulations

Across biological systems, cells undergo coordinated changes in gene expression, resulting in transcriptome dynamics that unfold within a low-dimensional manifold. While low-dimensional dynamics can be extracted using RNA velocity, these algorithms can be fragile and rely on heuristics lacking statistical control. Moreover, the estimated vector field is not dynamically consistent with the traversed gene expression manifold. To address these challenges, we introduce a Bayesian model of RNA velocity that couples velocity field and manifold estimation in a reformulated, unified framework, identifying the parameters of an explicit dynamical system. Focusing on the cell cycle, we implement VeloCycle to study gene regulation dynamics on one-dimensional periodic manifolds and validate its ability to infer cell cycle periods using live imaging. We also apply VeloCycle to reveal speed differences in regionally defined progenitors and Perturb-seq gene knockdowns. Overall, VeloCycle expands the single-cell RNA sequencing analysis toolkit with a modular and statistically consistent RNA velocity inference framework.

Statistical inference with a manifold-constrained RNA velocity model uncovers cell cycle speed modulations

Across a range of biological processes, cells undergo coordinated changes in gene expression, resulting in transcriptome dynamics that unfold within a low-dimensional manifold. Single-cell RNA-sequencing (scRNA-seq) only measures temporal snapshots of gene expression. However, information on the underlying low-dimensional dynamics can be extracted using RNA velocity, which models unspliced and spliced RNA abundances to estimate the rate of change of gene expression. Available RNA velocity algorithms can be fragile and rely on heuristics that lack statistical control. Moreover, the estimated vector field is not dynamically consistent with the traversed gene expression manifold. Here, we develop a generative model of RNA velocity and a Bayesian inference approach that solves these problems. Our model couples velocity field and manifold estimation in a reformulated, unified framework, so as to coherently identify the parameters of an autonomous dynamical system. Focusing on the cell cycle, we implemented VeloCycle to study gene regulation dynamics on one-dimensional periodic manifolds and validated using live-imaging its ability to infer actual cell cycle periods. We benchmarked RNA velocity inference with sensitivity analyses and demonstrated one- and multiple-sample testing. We also conducted Markov chain Monte Carlo inference on the model, uncovering key relationships between gene-specific kinetics and our gene-independent velocity estimate. Finally, we applied VeloCycle to in vivo samples and in vitro genome-wide Perturb-seq, revealing regionally-defined proliferation modes in neural progenitors and the effect of gene knockdowns on cell cycle speed. Ultimately, VeloCycle expands the scRNA-seq analysis toolkit with a modular and statistically rigorous RNA velocity inference framework.

Combined Wee1 and EGFR inhibition reveals synergistic antitumor effect in esophageal squamous cell carcinoma

Epidermal growth factor receptor (EGFR) is one of the most common amplified and overexpressed oncogenes in esophageal squamous cell carcinoma (ESCC), while the clinical efficacy of EGFR-targeted therapy in ESCC is dismal. Here, we evaluated the efficacy of dual blockage using monoclonal antibody against EGFR (Nimotuzumab) and an Wee1 inhibitor (AZD1775) in ESCC. We found that the mRNA and protein expression of EGFR and Wee1 were positively correlated in ESCC. Nimotuzumab-AZD1775 co-treatment inhibited tumor growth in PDX models with different drug susceptibility. Transcriptome sequencing and mass spectrometry analysis indicated that higher sensitive models showed enrichment of the PI3K/Akt or MAPK signaling pathway in Nimotuzumab-AZD1775 group compared with control group. In vitro experiments showed that the combination further inhibit PI3K/Akt and MAPK pathways compared to their monotherapy as indicated by downregulation of pAKT, pS6, pMEK, pErk and p-p38 MAPK. Furthermore, AZD1775 potentiated Nimotuzumab's antitumor effect through inducing apoptosis. Meanwhile, the bioinformatics analysis suggests the POLR2A might be candidate molecule of EGFR/Wee1 downstream. In conclusion, our work uncovers that EGFR-mAb Nimotuzumab combined with Wee1 inhibitor AZD1775 elicited potentiated anticancer activity against ESCC cell line and PDXs partially through PI3K/Akt and MAPK pathways blockade. These preclinical data raise the promising that ESCC patients may benefit from dual target EGFR and Wee1.

Icotinib derivatives as tyrosine kinase inhibitors with anti-esophageal squamous carcinoma activity

Previous report showed that a variety of icotinib derivatives bearing different 1,2,3-triazole moieties, which could be readily prepared via copper (I)-catalyzed cycloaddition (CuAAC) reaction between icotinib and different azides, exhibited interesting activity against different lung cancer cell lines such as H460, H1975, H1299, A549 or PC-9. To further expand the application scope of the compounds and to validate the function of triazole groups in drug design, the anti-cancer activity of these compounds against esophageal squamous carcinoma (ESCC) cells was tested herein. Preliminary MTT experiments suggested that these compounds were active against different ESCC cell lines such as KYSE70, KYSE410, or KYSE450 as well as their drug-resistant ones. Especially, compound 3l showed interesting anticancer activity against these cell lines. The mode of action was studied via molecular docking, SPR experiments and other biochemical studies, and 3l exhibited higher binding potential to wild-type EGFR than icotinib did. In vivo anticancer study showed that 3l could inhibit tumor growth of cell-line-derived xenografts in ESCC. Study also suggested that 3l was a potent inhibitor for EGFR-TK pathway. Combining these results, 3l represents a promising lead compound for the design of anti-cancer drugs against ESCC.

Cell Cycle Arrest and Apoptosis-Inducing Ability of Benzimidazole Derivatives: Design, Synthesis, Docking, and Biological Evaluation

In the current study, new benzimidazole-based 1,3,4-oxadiazole derivatives have been synthesized and characterized by NMR, IR, MS, and elemental analysis. The final compounds were screened for cytotoxicity against MDA-MB-231, SKOV3, and A549 cell lines and EGFR for inhibitory activities. Compounds 10 and 13 were found to be the most active against all the tested cell lines, comparable to doxorubicin, and exhibited significant inhibition on EGFR kinase, with IC₅₀ 0.33 and 0.38 μM, respectively, comparable to erlotinib (IC₅₀ 0.39 μM). Furthermore, these two compounds effectively suppressed cell cycle progression and induced cell apoptosis in MDA-MB-231, SKOV3, and A549 cell lines. The docking studies revealed that these compounds showed interactions similar to erlotinib at the EGFR site. It can be concluded that the synthesized molecules effectively inhibit EGFR, can arrest the cell cycle, and may trigger apoptosis and therefore, could be used as lead molecules in the development of new anticancer agents targeting EGFR kinase.

Design, Synthesis, and Antitumor Activity of Erlotinib Derivatives

Nineteen erlotinib derivatives bearing different 1,2,3-triazole moieties were designed, synthesized, and evaluated for their potential against different cancer cell lines. The structures of the synthesized compounds were confirmed via 1H NMR, 13C NMR, and HR MS. Preliminary antitumor activity assay results suggested that some compounds showed remarkable inhibitory activity against different cancer cell lines including the corresponding drug-resistant ones. Among these compounds, 3d was the most promising one with an IC50 of 7.17 ± 0.73 μM (KYSE70TR), 7.91 ± 0.61 μM (KYSE410TR), 10.02 ± 0.75 μM (KYSE450TR), 5.76 ± 0.3 3 μM (H1650TR), and 2.38 ± 0.17 μM (HCC827GR). A preliminary mechanism study suggested that compound 3d suppressed cancer cell proliferation through the EGFR-TK pathway.

The Level of Mesenchymal-Epithelial Transition Autophosphorylation is Correlated with Esophageal Squamous Cell Carcinoma Migration

Background

The MET receptor is a critical member of cancer-associated receptor tyrosine kinases and plays an important role in different biological activities, including differentiation, migration, and cell proliferation.

Methods

In this study, novel MET inhibitors were introduced and applied on esophageal squamous carcinoma cell line KYSE-30, and the level of proliferation and migration, as well as the activated form of MET receptor protein were assessed in the examined cells. The human KYSE-30 cell line was cultured according to ATCC recommendations. The mRNA level of the MET gene was measured in the examined cell line using the quantitative RT-PCR assay. Cytotoxicity evaluation test was performed at different concentrations of heterocyclic anti-MET compounds (i.e. D1, D2, D5, D6, D7, and D8). Finally, the capability of these compounds in MET receptor inhibition was evaluated using the migration assay and Western blot. All experiments were performed in triplicate and repeated three times with similar results.

Results

Cell growth and proliferation were significantly inhibited (p ≤ 0.05) by all the above-mentioned compounds. Moreover, the majority of compounds significantly prevented the cell migration (p ≤ 0.05) and inhibited MET autophosphorylation. Interestingly, the level of phosphorylated MET was significantly correlated with KYSE-30 cell migration.

Conclusion

The obtained data introduced and confirmed the biological activities of the mentioned novel compounds in KYSE-30 cells and proposed that the therapeutic inhibition of MET with these compounds may be a powerful approach for inhibiting cancer cell migration and proliferation although some structural optimizations are needed to improve their inhibitory functions.

Synthesis, docking study, and in vitro anticancer evaluation of new flufenamic acid derivatives

Novel compounds (6–10) were synthesized and confirmed by spectroscopic analysis, including AT-IR, 1HNMR and CHNS. Their cytotoxic effect was evaluated by MTT assay against two cancer cell lines and two normal cell types. Compound 7 exhibited anticancer activity against MCF-7 breast cancer cell line (GI50 = 63.9 µg/ml, 148 µM), without any effect against A549 lung cancer cells, or the normal cells. Compound 7 caused cytotoxicity in MCF-7 breast cancer cells by apoptotic cell death, as suggested by fragmented nuclei after DAPI staining and agarose gel electrophoresis. In addition, treating MCF-7 cells with compound 7 resulted in an increase in the level of caspase 9 mRNA level, and its activation. Moreover, compound 7-treated MCF-7 cells showed enhanced cytochrome c release from the mitochondria to the cytosol, signifying an induction of the intrinsic apoptotic pathway. Finally, compound 7 exhibited epidermal growth factor receptor (EGFR) kinase inhibitory activity at (EC50 = 0.13 µM), which was matched by molecular docking studies that showed compound 7 might be an important EGFR kinase inhibitor.

Efficacy and safety of anti-epidermal growth factor receptor agents for the treatment of oesophageal cancer: a systematic review and meta-analysis

OBJECTIVES

Despite remarkable advances in the treatment of oesophageal cancer (OC), the role of antiepidermal growth factor receptor (anti-EGFR) agents in treating OC remains controversial. Herein, a systematic review and meta-analysis were conducted to elucidate the efficacy and safety of anti-EGFR agents in patients with OC.

DESIGN

Meta-analysis of randomised controlled trials (RCTs) identified by searching the PubMed, Embase, Web of Science, ClinicalTrials.gov, Cochrane Library, Chinese Biology Medicine, China National Knowledge Infrastructure and Wanfang Data Knowledge Service Platform databases from inception to December 2019. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

SETTING

RCTs from any country and healthcare setting.

PARTICIPANTS

Patients with OC.

INTERVENTIONS

Combination therapy with anti-EGFR agents and conventional treatments versus conventional treatments alone in patients with OC.

PRIMARY AND SECONDARY OUTCOME MEASURES

Overall survival (OS) and progression-free survival (PFS) were primary outcome measures, and objective response rate (ORR), disease control rate (DCR) and treatment toxicities were secondary outcome measures.

RESULTS

In total, 25 RCTs comprising 3406 patients with OC were included. Overall, anti-EGFR treatment significantly improved the OS (HR: 0.81, 95% CI 0.74 to 0.89, p<0.00001), ORR (relative risk (RR): 1.33, 95% CI 1.16 to 1.52, p<0.0001) and DCR (RR: 1.22, 95% CI 1.11 to 1.34, p<0.0001) but not PFS (HR: 0.91, 95% CI 0.76 to 1.08, p=0.26). Anti-EGFR treatment was significantly associated with higher incidences of myelosuppression, diarrhoea, acne-like rash and hypomagnesaemia.

CONCLUSIONS

Overall, anti-EGFR agents have positive effects on OS, the ORR and DCR in OC. However, considering the high incidence of adverse effects, such as myelosuppression, diarrhoea, acne-like rashes and hypomagnesaemia, careful monitoring of patients with OC is recommended during anti-EGFR treatment.

TRIAL REGISTRATION NUMBER

CRD42020169230.

Rethink of EGFR in Cancer With Its Kinase Independent Function on Board

The epidermal growth factor receptor (EGFR) is one of most potent oncogenes that are commonly altered in cancers. As a receptor tyrosine kinase, EGFR's kinase activity has been serving as the primary target for developing cancer therapeutics, namely the EGFR inhibitors including small molecules targeting its ATP binding pocket and monoclonal antibodies targeting its ligand binding domains. EGFR inhibitors have produced impressive therapeutic benefits to responsive types of cancers. However, acquired and innate resistances have precluded current anti-EGFR agents from offering sustainable benefits to initially responsive cancers and benefits to EGFR-positive cancers that are innately resistant. Recent years have witnessed a realization that EGFR possesses kinase-independent (KID) pro-survival functions in cancer cells. This new knowledge has offered a different angle of understanding of EGFR in cancer and opened a new avenue of targeting EGFR for cancer therapy. There are already many excellent reviews on the role of EGFR with a focus on its kinase-dependent functions and mechanisms of resistance to EGFR targeted therapies. The present opinion aims to initiate a fresh discussion about the function of EGFR in cancer cells by laying out some unanswered questions pertaining to EGFR in cancer cells, by rethinking the unmet therapeutic challenges from a view of EGFR's KID function, and by proposing novel approaches to target the KID functions of EGFR for cancer treatment.

Phase I dose-escalation trial of Sym004, an anti-EGFR antibody mixture, in Japanese patients with advanced solid tumors

Sym004 is a 1:1 mixture of two antibodies targeting non‐overlapping epitopes of the epidermal growth factor receptor that antagonizes ligand binding and induces receptor downregulation. In preclinical models, it has superior antitumor activity to cetuximab and panitumumab. Japanese adults aged ≥20 years with an Eastern Cooperative Oncology Group status of 0/1 and life expectancy ≥3 months were eligible. Patients in Part A (dose escalation) had refractory or recurrent late‐stage solid tumors and received Sym004 6 mg/kg/wk (n = 3), 9 mg/kg loading/6 mg/kg/wk (n = 6), 12 mg/kg/wk (n = 6), or 18 mg/kg biweekly (n = 6). Patients in expansion Part B (n = 30) had esophageal squamous cell carcinoma and received Sym004 at the dose recommended from Part A. Fifty‐one patients received Sym004. No dose‐limiting toxicities were observed in Part A. A dose of 12 mg/kg/wk was selected for Part B. All patients in Part B experienced treatment‐related adverse events, most commonly dermatitis acneiform (76.7%). Eighteen grade ≥3 treatment‐related adverse events and five serious adverse events occurred (cardiac arrest, lung infection, interstitial lung disease, toxic skin eruption, blood creatinine increase). Two patients had treatment‐related adverse events resulting in death (cardiac arrest and blood creatinine increase). Five patients in Part B had a best overall response of partial response, 12 stable diseases and 12 disease progression (1 not evaluable). The objective response rate was 16.7% (95% CI: 5.6%‐34.7%). Sym004 therapy was well tolerated with no dose‐limiting toxicities at any dose studied. Evidence of antitumor activity was seen in patients with esophageal squamous cell carcinoma. ClinicalTrials.gov Identifier: NCT01955473.

A phase II study of concurrent chemoradiotherapy and erlotinib for inoperable esophageal squamous cell carcinoma

Cisplatin-based concurrent chemoradiotherapy for patients with unresectable, locally advanced esophageal squamous cell carcinoma (ESCC) is associated with significant toxicities that are often intolerable. Prognosis for this subgroup of patients remains poor, and new therapeutic approaches are urgently needed. We investigated the efficacy and safety of paclitaxel combined with erlotinib and concurrent radiotherapy in patients with inoperable ESCC. Erlotinib (150 mg) was administered daily for 60 days beginning at the start of radiotherapy, and paclitaxel (45 mg/m²) was administered weekly along with intensity modulated conformal radiotherapy (60 Gy in 30 fractions). The median follow-up time was 21 months. The associations between EGFR and VEGF expression and treatment outcome were evaluated. Among the 21 patients treated, the overall response rate (CR + PR) was 85.6%. The median LPFS, PFS and OS were: 17.5, 14.3, and 22.9 months, respectively. Treatment-related grade 3 toxicities included esophagitis (two patients) and hypoleukemia (one patient). Grade 4 pulmonary toxicity was observed in one patient. Patients expressing EGFR had longer PFS, while those expressing VEGF or with a history of smoking had worse outcomes. Weekly paclitaxel combined with erlotinib and concurrent radiotherapy shows promise as an effective, tolerated regimen for patients with inoperable ESCC.

Squamous Cell Carcinoma of the Umbilicus: Management of an Unusual Localization

We describe the case of a squamous cell carcinoma spreading to the skin and regional lymph nodes from the umbilicus. Bilateral inguinal lymphadenectomy and a session of electrochemotherapy with bleomycin 15 mg/m2 were performed. However, because of the development of new cutaneous nodules in the abdominopelvic region, we performed targeted palliative therapy with erlotinib 150 mg/day. Targeted adjuvant therapy was preferred to the use of a major cytotoxic agent because of the high risk of superinfection and heart failure. Erlotinib produced a partial clinical response with reduction of the number and size of the skin nodules. CT scan performed after 60 days of treatment did not show any new lesions.

To our knowledge, this is the first report of an umbilical metastatic squamous cell carcinoma treated with modern targeted therapy. This therapeutic strategy can be considered a valid palliative option in the management of metastatic cutaneous nodules of this rare primary site.

MicroRNA-1 inhibits tumorigenicity of esophageal squamous cell carcinoma and enhances sensitivity to gefitinib

Dysregulation of microRNAs in various types of human cancer promote or suppress oncogenesis. MicroRNA (miR)-1 was previously revealed to function as a tumor suppressor in prostate cancer cells, and its expression was associated with reduced metastatic potential in lung cancer. The present study investigated the role of miR-1 and its association with phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α (PIK3CA) in the pathophysiology of esophageal squamous cell carcinoma (ESCC), and analyzed the effects of miR-1 inhibitor or mimics on sensitivity to epidermal growth factor receptor-tyrosine kinase inhibitors, the alterations of cell cycle distribution and apoptosis in ESCC cells. Compared with normal tissues, the level of miR-1 expression was significantly lower and PIK3CA expression was higher in ESCC tissues. The level of miR-1 expression was also inversely associated with the level of PIK3CA mRNA expression. Low miR-1 and high PIK3CA expression levels were strongly associated with lymph node metastasis, and the level of miR-1 expression was negatively associated with clinical Tumor-Node-Metastasis stage. Furthermore, exogenous expression of miR-1 inhibited growth, arrested cell cycle in the G₁ phase and increased apoptosis in ESCC cells, whereas it decreased PIK3CA protein expression levels. Furthermore, overexpression of miR-1 increased the sensitivity of ESCC cells to the anticancer drug, gefitinib. A possible mechanism for this increased sensitivity to gefitinib may be inactivation of the PIK3CA signaling pathway. To the best of our knowledge, this is the first time that the results of the present study demonstrated that miR-1 upregulation may be a potential strategy for the treatment of human ESCC.

A new model system identifies epidermal growth factor receptor-human epidermal growth factor receptor 2 (HER2) and HER2-human epidermal growth factor receptor 3 heterodimers as potent inducers of oesophageal epithelial cell invasion

Oesophageal squamous cell carcinomas and oesophageal adenocarcinomas show distinct patterns of ErbB expression and dimers. The functional effects of specific ErbB homodimers or heterodimers on oesophageal (cancer) cell behaviour, particularly invasion during early carcinogenesis, remain unknown. Here, a new cellular model system for controlled activation of epidermal growth factor receptor (EGFR) or human epidermal growth factor receptor 2 (HER2) and EGFR-HER2 or HER2-human epidermal growth factor receptor 3 (HER3) homodimers and heterodimers was studied in non-neoplastic squamous oesophageal epithelial Het-1A cells. EGFR, HER2 and HER3 intracellular domains (ICDs) were fused to dimerization domains (DmrA/DmrA and DmrC), and transduced into Het-1A cells lacking ErbB expression. Dimerization of EGFR, HER2 or EGFR-HER2 and HER2-HER3 ICDs was induced by synthetic ligands (A/A or A/C dimerizers). This was accompanied by phosphorylation of the respective EGFR, HER2 and HER3 ICDs and activation of distinct downstream signalling pathways, such as phospholipase Cγ1, Akt, STAT and Src family kinases. Phenotypically, ErbB dimers caused cell rounding and non-apoptotic blebbing, specifically in EGFR-HER2 and HER2-HER3 heterodimer cells. In a Transwell assay, cell migration velocity was elevated in HER2 dimer cells as compared with empty vector cells. In addition, HER2 dimer cells showed in increased cell invasion, reaching significance for induced HER2-HER3 heterodimers (P = 0.015). Importantly, in three-dimensional organotypic cultures, empty vector cells grew as a superficial cell layer, resembling oesophageal squamous epithelium. In contrast, induced HER2 homodimer cells were highly invasive into the matrix and formed cell clusters. This was associated with partial loss of cytokeratin 7 (when HER2 homodimers were modelled) and p63 (when EGFR-HER2 heterodimers were modelled), which suggests a change or loss of squamous cell differentiation. Controlled activation of specific EGFR, HER2 and HER3 homodimers and heterodimers caused oesophageal squamous epithelial cell migration and/or invasion, especially in a three-dimensional microenvironment, thereby functionally identifying ErbB homodimers and heterodimers as important drivers of oesophageal carcinogenesis. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Scorpion (Androctonus bicolor) venom exhibits cytotoxicity and induces cell cycle arrest and apoptosis in breast and colorectal cancer cell lines

OBJECTIVES

The defective apoptosis is believed to play a major role in the survival and proliferation of neoplastic cells. Hence, the induction of apoptosis in cancer cells is one of the targets for cancer treatment. Researchers are considering scorpion venom as a potent natural source for cancer treatment because it contains many bioactive compounds. The main objective of the current study is to evaluate the anticancer property of Androctonus bicolor scorpion venom on cancer cells.

MATERIALS AND METHODS

Scorpions were milked by electrical stimulation of telsons and lyophilized. The breast (MDA-MB-231) and colorectal (HCT-8) cancer cells were maintained in appropriate condition. The venom cytotoxicity was assessed by 3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay, and the cellular and nuclear changes were studied with propidium iodide and 4',6-diamidino-2-phenylindole stain, respectively. The cell cycle arrest was examined using muse cell analyzer.

RESULTS

The A. bicolor venom exerted cytotoxic effects on MDA-MB-231 and HCT-8 cells in a dose- and duration-dependent manner and induced apoptotic cell death. The treatment with this venom arrests the cancer cells in G0/G1 phase of cell cycle.

CONCLUSIONS

The venom selectively induces the rate of apoptosis in MDA-MB-231 and HCT-8 cells as reflected by morphological and cell cycle studies. To the best of our knowledge, this is the first scientific evidence demonstrating the induction of apoptosis and cell cycle arrest by A. bicolor scorpion venom.

Novel zinc phthalocyanine as a promising photosensitizer for photodynamic treatment of esophageal cancer

Photodynamic therapy (PDT) has gathered much attention in the field of cancer treatment and is increasingly used as an alternative solution for esophageal cancer therapy. However, there is a constant need for improving the effectiveness and tolerability of the applied photosensitizers (PS). Here, we propose tetra-triethyleneoxysulfonyl substituted zinc phthalocyanine (ZnPc) as a promising PS for photodynamic treatment of esophageal cancer. ZnPc-induced phototoxicity was studied in two human esophageal cancer cell lines: OE-33 (adenocarcinoma) and Kyse-140 (squamous cell carcinoma). In vitro studies focused on the uptake and intracellular distribution of the novel ZnPc as well as on its growth inhibitory potential, reactive oxygen species (ROS) formation and the induction of apoptosis. The chicken chorioallantoic membrane assay (CAM assay) and studies on native Wistar rats were employed to determine the antineoplastic and antiangiogenic activity of ZnPc-PDT as well as the tolerability and safety of non-photoactivated ZnPc in vivo. ZnPc was taken up by cancer cells in a dose- and time-dependent manner and showed a homogeneous cytoplasmic distribution. Photoactivation of ZnPc-loaded (1-10 µM) cells led to a dose-dependent growth inhibition of esophageal adenocarcinoma and squamous cell carcinoma cells of >90%. The antiproliferative effect was based on ROS-induced cytotoxicity and the induction of mitochondria-driven apoptosis. In vivo studies on esophageal tumor plaques grown on the CAM revealed pronounced antiangiogenic and antineoplastic effects. ZnPc-PDT caused long-lasting changes in the vascular architecture and a marked reduction of tumor feeding blood vessels. Animal studies confirmed the good tolerability and systemic safety of ZnPc, as no changes in immunological, behavioral and organic parameters could be detected upon treatment with the non-photoactivated ZnPc. Our findings show the extraordinary photoactive potential of the novel ZnPc as a photosensitizer for PDT of esophageal cancer.

Synergistic effect of targeting the epidermal growth factor receptor and hyaluronan synthesis in oesophageal squamous cell carcinoma cells

BACKGROUND AND PURPOSE

Worldwide, oesophageal cancer is the eighth most common cancer and has a very poor survival rate. In order to identify new tolerable treatment options for oesophageal squamous cell carcinoma (ESCC), erlotinib was tested with moderate efficacy in phase I and II studies. As 4-methylumbelliferone (4-MU), an hyaluronan (HA) synthesis inhibitor showed anti-cancer effects in vitro, and in ESCC xenograft tumours, we investigated whether the anti-cancer effects of erlotinib could be augmented by combining it with 4-MU.

EXPERIMENTAL APPROACH

ESCC cell lines were treated with erlotinib or gefitinib (1 μmol·L^-1 ) and 4-MU (300 μmol·L^-1 ), and the cell count, cell cycle progression and migration were determined as compared to the single agents and the solvent-control.

KEY RESULTS

The combination of erlotinib and 4-MU synergistically inhibited the proliferation of ESCC cell lines. Furthermore, the migration speed of ESCC cell line KYSE-410 in gap closure assays was significantly reduced by the combination of erlotinib and 4-MU. Decreased ERK phosphorylation could explain the anti-proliferative and anti-migratory effects in the combined treatment group. Finally, the combination was additionally able to decrease the growth of multicellular tumour spheroids, a three-dimensional cell culture model that was associated with sustained inhibition of ERK1/2 phosphorylation.

CONCLUSIONS AND IMPLICATIONS

The combination of 4-MU and erlotinib showed promising anti-cancer efficacies in the ESCC cell lines.

Biological evaluation of 4,5-diarylimidazoles with hydroxamic acid appendages as novel dual mode anticancer agents

PURPOSE

New (4-aryl-1-methylimidazol-5-yl)cinnamoylhydroxamic acids were prepared as potential dual mode anticancer agents combining the antivascular effect of the 4,5-diarylimidazole moiety and the histone deacetylases (HDAC) inhibition by the cinnamoyl hydroxamate.

METHODS

Their antiproliferative activity against a panel of primary cells and cancer cell lines was determined by MTT assays and their apoptosis induction by caspase-3 activation. Their ability to reduce the activity of HDAC was measured by enzymatic assays and Western blot analyses of cellular HDAC substrates. Additional effects on cancer cell migration were ascertained via immunofluorescence staining of cytoskeleton components and three-dimensional migration assays. The chorioallantoic membrane assay was used as an in vivo model to assess their antiangiogenic properties.

RESULTS

The 4-phenyl- and 4-(p-methoxyphenyl)-imidazole derivatives had a greater antiproliferative and apoptosis inducing effect in a variety of cancer cell lines when compared with the approved HDAC inhibitor SAHA, and most distinctly so in non-malignant human umbilical vein endothelial cells. Like SAHA, both compounds acted as pan-HDAC inhibitors. In 518A2 melanoma cells, they led to hyperacetylation of histones and of the cytoplasmic HDAC6 substrate alpha-tubulin. As a consequence, they inhibited the migration and invasion of these cells in transwell invasion assays. In keeping with its pronounced impact on endothelial cells, the 4-phenyl-imidazole derivative also inhibited the growth and sprouting of blood vessels in the chorioallantoic membrane of fertilized hen eggs.

CONCLUSIONS

The 4-phenyl- and 4-(p-methoxyphenyl)-imidazole compounds combine the antivascular effects of 4,5-diarylimidazoles with HDAC inhibition by cinnamoyl hydroxamates and show additional antimetastatic activity. They are promising candidates for pleiotropic HDAC inhibitors.

Simultaneous determination of bupropion, metroprolol, midazolam, phenacetin, omeprazole and tolbutamide in rat plasma by UPLC-MS/MS and its application to cytochrome P450 activity study in rats

A specific ultra-performance liquid chromatography tandem mass spectrometry method is described for the simultaneous determination of bupropion, metroprolol, midazolam, phenacetin, omeprazole and tolbutamide in rat plasma with diazepam as internal standard, which are the six probe drugs of the six cytochrome P450 isoforms CYP2B6, CYP2D6, CYP3A4, CYP1A2, CYP2C19 and CYP2C9. Plasma samples were protein precipitated with acetonitrile. The chromatographic separation was achieved using a UPLC® BEH C18 column (2.1 × 100 mm, 1.7 µm). The mobile phase consisted of acetonitrile and water (containing 0.1% formic acid) with gradient elution. The triple quadrupole mass spectrometric detection was operated by multiple reaction monitoring in positive electrospray ionization. The precisions were <13%, and the accuracy ranged from 93.3 to 110.4%. The extraction efficiency was >90.5%, and the matrix effects ranged from 84.3 to 114.2%. The calibration curves in plasma were linear in the range of 2-2000 ng/mL, with correlation coefficient (r(2) ) >0.995. The method was successfully applied to pharmacokinetic studies of the six probe drugs of the six CYP450 isoforms and used to evaluate the effects of erlotinib on the activities of CYP2B6, CYP2D6, CYP3A4, CYP1A2, CYP2C19 and CYP2C9 in rats. Erlotinib may inhibit the activity of CYP2B6 and CYP3A4, and may induce CYP2C9 of rats.

Squamous Cell Carcinoma - Similarities and Differences among Anatomical Sites

Squamous cell carcinoma (SCC) is an epithelial malignancy involving many anatomical sites and is the most common cancer capable of metastatic spread. Development of early diagnosis methods and novel therapeutics are important for prevention and mortality reduction. In this effort, numerous molecular alterations have been described in SCCs. SCCs share many phenotypic and molecular characteristics, but they have not been extensively compared. This article reviews SCC as a disease, including: epidemiology, pathology, risk factors, molecular characteristics, prognostic markers, targeted therapy, and a new approach to studying SCCs. Through this comparison, several themes are apparent. For example, HPV infection is a common risk factor among the four major SCCs (NMSC, HNSC, ESCC, and NSCLC) and molecular abnormalities in cell-cycle regulation and signal transduction predominate. These data reveal that the molecular insights, new markers, and drug targets discovered in individual SCCs may shed light on this type of cancer as a whole.

Downregulation of VGLL4 in the progression of esophageal squamous cell carcinoma

VGLL4, a member of the Vestigial-like (VGLL) proteins, has been reported to be dysregulated in several cancer types. However, its function in esophageal squamous cell carcinoma (ESCC) remains poorly understood. Here, it was found that the expression level of VGLL4 was decreased in ESCC tissues. Moreover, forced expression of VGLL4 in ESCC cells inhibited cell growth and migration, while knockdown of VGLL4 expression promoted the tumorigenecity of ESCC cells. Mechanistically, VGLL4 regulated the growth and motility of ESCC cells through downregulating the expression of connective tissue growth factor (CTGF), a known oncogene in the progression of ESCC. Taken together, our study suggested that downregulation of VGLL4 was very important in the progression of ESCC, and restoring the function of VGLL4 might be a promising therapeutic strategy for ESCC.

ErbB targeting inhibitors repress cell migration of esophageal squamous cell carcinoma and adenocarcinoma cells by distinct signaling pathways

ErbB family receptor tyrosine kinases (ErbBs) play a role in cell adhesion and migration and are frequently overexpressed in esophageal squamous cell carcinomas (ESCCs) or esophageal adenocarcinomas (EACs). Targeting ErbBs by tyrosine kinase inhibitors (TKIs) may therefore limit esophageal cancer cell migration. Here, we studied the impact of TKIs on ErbB dimerization, cell signaling pathways, and cell migration in three esophageal cell lines: OE21 (ESCC), OE33 (EAC), and Het-1A (non-neoplastic esophageal epithelium). In OE21 cells, the TKIs erlotinib, gefitinib, and lapatinib slightly affected epidermal growth factor receptor EGFR/EGFR, but not EGFR/HER2 dimerization as detected by in situ proximity ligation assay (in situ PLA). Still, TKIs inhibited ERK1/2, Akt, STAT3, and RhoA activity in OE21 cells, as assessed by Western blot, antibody arrays, and Rho GTPase effector pull-down assays. This was accompanied by reduced OE21 cell migration, induction of focal adhesions, and actin cytoskeleton reorganization, as shown by Oris™ migration assay and focal adhesion kinase (FAK)/phalloidin staining. In contrast, in OE33 cells, only lapatinib decreased STAT5, Src family kinase (SFK), and FAK activity as well as β-catenin expression. This impeded cell migration and induced morphological changes in OE33 cells. No alterations were seen for the non-neoplastic Het-1A cells. Thus, we identified the ErbB signaling network as regulator of esophageal cancer cell's actin cytoskeleton, focal adhesions, and cell migration. ErbB targeted TKIs therefore also limit ESCC and EAC cell motility and migration.

KEY MESSAGE

Clinical tyrosine kinase inhibitors (TKIs) reduce esophageal cancer cell migration. Loss of cell migration is linked to reduced Akt, ERK1/2, STAT (3 or 5), FAK, SFKs, and RhoA activity. Clinical TKIs act via distinct signaling in the two main histotypes of esophageal cancer.

Enhanced anti-angiogenic effect of E7820 in combination with erlotinib in epidermal growth factor receptor-tyrosine kinase inhibitor-resistant non-small-cell lung cancer xenograft models

Most non-small-cell lung cancers (NSCLCs) harboring activating mutations in the epidermal growth factor receptor (EGFR) are initially responsive to EGFR tyrosine kinase inhibitors (EGFR-TKIs); however, they invariably develop resistance to these drugs. E7820 is an angiogenesis inhibitor that decreases integrin-α2 expression and is currently undergoing clinical trials. We investigated whether E7820 in combination with erlotinib, an EGFR-TKI, could overcome EGFR-TKI-resistance in the NSCLC cell lines A549 (KRAS; G12S), H1975 (EGFR; L858R/T790M), and H1650 (PTEN; loss, EGFR; exon 19 deletion), which are resistant to erlotinib. Immunohistochemical analysis was carried out in xenografted tumors to investigate anti-angiogenesis activity and endothelial cell apoptosis levels by endothelial cell marker CD31 and TUNEL staining, respectively. Treatment with E7820 (50 mg/kg) with erlotinib (60 mg/kg) showed a synergistic antitumor effect in three xenograft models. Immunohistochemical analysis indicated that combined treatment with E7820 and erlotinib significantly decreased microvessel density and increased apoptosis of tumor-associated endothelial cells compared with use of only one of the agents. This combination increased apoptosis in HUVECs through activation of both intrinsic and extrinsic apoptosis pathways in vitro. The combination of E7820 with erlotinib is an alternative strategy to overcome erlotinib resistance in NSCLC by enhancement of the anti-angiogenic activity of E7820.

EGFR, HER2 and HER3 dimerization patterns guide targeted inhibition in two histotypes of esophageal cancer

Receptor tyrosine kinases (RTKs) are in the focus of targeted therapy for epithelial tumors. Our study addressed the role of EGFR, HER2 and HER3 expression and dimerization in esophageal cancers in situ and in vitro in the context of therapeutic EGFR and HER2 inhibitors. In archival pretreatment biopsies of esophageal carcinomas (n = 110), EGFR was preferentially expressed in esophageal squamous cell carcinomas (ESCCs) (22.4%; p = 0.088) and HER2 (34.4%; p < 0.001) with HER3 (91.5%; p < 0.001) in esophageal (Barrett's) adenocarcinomas (EACs). In situ proximity ligation assays revealed mainly EGFR and HER2 homodimers in ESCC and EAC cases, respectively. However, EAC cases also exhibited HER2/HER3 heterodimers. In vitro ESCC (OE21) cells displayed a significant response to erlotinib, gefitinib and lapatinib, with loss of AKT phosphorylation, G0/G1 cell cycle arrest and induction of apoptosis. In EAC cells (OE19, OE33 and SK-GT-4), lapatinib was similarly effective in strongly HER2-positive (mainly HER2 homodimers and some HER2/EGFR heterodimers) OE19 and OE33 cells. The HER2-targeting antibodies (trastuzumab and pertuzumab) given alone were largely ineffective in ESCC and EAC cells. However, both antibodies significantly induced antibody-dependent cellular cytotoxicity in EAC (OE19 and OE33) cells upon co-culture with peripheral blood mononuclear cells. The study reveals that overexpression of EGFR and HER2 predominantly results in homodimers in ESCCs and EACs, respectively. Still, some EACs also show HER2 dimerization plasticity, e.g., with HER3. Such RTK dimerization patterns affect responses to EGFR and HER2 targeting inhibitors in ESCC and EAC cells in vitro and hence may influence future prediction for particularly HER2-targeting inhibitors in EACs.

Epidermal growth factor receptor: an important target in esophageal cancer

INTRODUCTION

Even after complete tumor removal by surgery, the clinical outcomes remain poor in patients with advanced esophageal cancer, justifying the need for new treatment options. Epidermal growth factor receptor (EGFR) is a molecular target for antibody-based therapy in various cancer types, and it may play important roles in the development of esophageal cancer.

AREAS COVERED

This review evaluates the expression, function, and mechanism of EGFR in esophageal cancer and analyzes its value for the prognosis and therapy of esophageal cancer. Future developments toward the clinical applications of EGFR to cancer treatment are also envisaged.

EXPERT OPINION

EGFR may function as an ideal therapeutic target for esophageal cancer. Further investigation of epidermal growth-factor-receptor-mediated pathways will push insight into the novel strategies of target therapy for esophageal cancer. More clinical trials should be performed to promote the success of therapeutic-clinical use of EGFR and its targets in esophageal cancer.

Concurrent erlotinib and radiotherapy for chemoradiotherapy-intolerant esophageal squamous cell carcinoma patients: results of a pilot study

Concurrent chemoradiotherapy is the standard treatment for patients with locally advanced esophageal squamous cell carcinoma. However, a number of patients present intolerance to chemoradiotherapy because of advanced age or malnutrition. Erlotinib, an inhibitor of epidermal growth factor receptor tyrosine kinase, was shown to be effective in treating esophageal carcinoma, with mild toxicities. In this pilot study, we investigated the safety and efficacy of concurrent erlotinib and radiotherapy as an alternative treatment modality for esophageal carcinoma patients who are intolerant to chemoradiotherapy. Pathologically diagnosed esophageal squamous cell carcinoma patients who could not tolerate concurrent chemoradiotherapy were enrolled. All patients were treated with concurrent erlotinib and intensity-modulated radiation therapy. Erlotinib was given orally for 60 days (150 mg per day). Radiotherapy (total dose, 60 Gy) was given at dosages of 2 Gy for a total of 30 times. Immunohistochemical staining was performed to assess epidermal growth factor receptor expression. Toxicities were evaluated according to the National Cancer Institute Common Terminology Criteria for Adverse Events (version 3.0). The overall survival, progression-free survival, and local-regional relapse-free survival were calculated using the Kaplan-Meier method. Between December 2007 and March 2011, 18 patients were enrolled. The median age was 71.5 years. Primary disease was stages II, III, and IV in 3, 8, and 4 patients, respectively. There were three patients with recurrent disease after radical surgery. The median follow-up time was 17.2 months. Grade 3 esophagitis and skin rash were observed in five (27.8%) and two (11.1%) patients, respectively. Radiation pneumonitis of grades 2 and 5 was observed in one patient each. No grade 3/4 impaired liver function or hematological toxicity was observed. At 1 month after radiotherapy, two (11.1%) patients achieved complete response, 11 (61.1%) patients achieved partial response, and 5 (27.8%) patients had stable disease. The median time of overall survival and progression-free survival was 21.1 and 12 months, respectively. Two-year overall survival, progression-free survival, and local-regional relapse-free survival were 44.4%, 38.9%, and 66.7%, respectively. Five of six patients examined for epidermal growth factor receptor had high expression levels (3+). The relationship between epidermal growth factor receptor expression and treatment outcomes could not be concluded. For esophageal squamous cell carcinoma patients who cannot tolerate chemoradiotherapy, concurrent erlotinib and radiotherapy are tolerable and effective. Valuable markers to predict the effect of erlotinib should be exploited in future studies.

Targeting key signalling pathways in oesophageal adenocarcinoma: A reality for personalised medicine?

Cancer treatments are rapidly changing. Curative treatment for oesophageal adenocarcinoma currently involves surgery and cytotoxic chemotherapy or chemoradiotherapy. Outcomes for both regimes are generally poor as a result of tumor recurrence. We have reviewed the key signalling pathways associated with oesophageal adenocarcinomas and discussed the recent trials of novel agents that attempt to target these pathways. There are many trials underway with the aim of improving survival in oesophageal cancer. Currently, phase 2 and 3 trials are focused on MAP kinase inhibition, either through inhibition of growth factor receptors or signal transducer proteins. In order to avoid tumor resistance, it appears to be clear that targeted therapy will be needed to combat the multiple signalling pathways that are in operation in oesophageal adenocarcinomas. This may be achievable in the future with the advent of gene signatures and a combinatorial approach.

Erlotinib-mediated inhibition of EGFR signaling induces metabolic oxidative stress through NOX4

Redox regulation of epidermal growth factor receptor (EGFR) signaling helps protect cells against oxidative stress. In this study, we investigated whether the cytotoxicity of an EGFR tyrosine kinase inhibitor, erlotinib (ERL), was mediated by induction of oxidative stress in human head and neck cancer (HNSCC) cells. ERL elicited cytotoxicity in vitro and in vivo while increasing a panel of oxidative stress parameters which were all reversible by the antioxidant N-acetyl cysteine. Knockdown of EGFR by using siRNA similarly increased these oxidative stress parameters. Overexpression of mitochondrial targeted catalase but not superoxide dismutase reversed ERL-induced cytotoxicity. Consistent with a general role for NADPH oxidase (NOX) enzymes in ERL-induced oxidative stress, ERL-induced cytotoxicity was reversed by diphenylene iodonium, a NOX complex inhibitor. ERL reduced the expression of NOX1, NOX2, and NOX5 but induced the expression of NOX4. Knockdown of NOX4 by using siRNA protected HNSCC cells from ERL-induced cytotoxicity and oxidative stress. Our findings support the concept that ERL-induced cytotoxicity is based on a specific mechanism of oxidative stress mediated by hydrogen peroxide production through NOX4 signaling.

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.

Isolation and characterization of erlotinib-resistant human non-small cell lung cancer A549 cells

Erlotinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, is an effective therapy for non-small cell lung cancer (NSCLC). However, resistance to erlotinib reduces its efficacy. To investigate the basis of erlotinib resistance, we isolated erlotinib-resistant human NSCLC A549 cells, termed A549/ER cells. The A549/ER cells were found to be resistant to erlotinib, as well as paclitaxel and gemcitabine. We then performed a PCR array to investigate the resistance to erlotinib in A549/ER cells. EGFR expression in A549/ER cells was decreased compared to A549 cells. The expression of fibroblast growth factor 2 (FGF2) and p21 in A549/ER was increased when compared to A549 cells. Our results suggest that the down-regulation of EGFR and up-regulation of FGF2 is related to resistance to erlotinib in A549/ER cells.

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.

Synergistic growth inhibition of squamous cell carcinoma of the head and neck by erlotinib and epigallocatechin-3-gallate: the role of p53-dependent inhibition of nuclear factor-kappaB

We have previously reported that the green tea polyphenol epigallocatechin-3-gallate (EGCG) and the epidermal growth factor receptor-tyrosine kinase inhibitor erlotinib had synergistic growth-inhibitory effects in cell culture and a nude mouse xenograft model of squamous cell carcinoma of the head and neck. However, the mechanism of their antitumor synergism is not fully understood. In the current study, we investigate the mechanism of their synergistic growth-inhibitory effects. The treatment of squamous cell carcinoma of the head and neck cell lines with erlotinib time-dependently increased the expression of cell cycle regulatory proteins p21 and p27 and apoptosis regulatory protein Bim. EGCG alone had very little or no effect on the expression of these proteins among the cell lines. However, simultaneous treatment with EGCG and erlotinib strongly inhibited erlotinib-induced expression of p21 and p27 without affecting the expression of Bim. Moreover, erlotinib increased the expression of p53 protein, the ablation of which by short hairpin RNA strongly inhibited EGCG- and erlotinib-mediated growth inhibition and the expression of p21, p27, and Bim. In addition, combined treatment with erlotinib and EGCG inhibited the protein level of p65 subunit of nuclear factor-kappaB and its transcriptional target Bcl-2, but failed to do so in cells with ablated p53. Taken together, our results, for the first time, suggest that erlotinib treatment activates p53, which plays a critical role in synergistic growth inhibition by erlotinib and EGCG via inhibiting nuclear factor-kappaB signaling pathway. Characterizing the underlying mechanisms of EGCG and erlotinib synergism will provide an important rationale for chemoprevention or treatment trials using this combination.

Targets for molecular therapy in esophageal squamous cell carcinoma: an immunohistochemical analysis

Neoadjuvant chemotherapy may improve the outcome of esophageal cancer after esophagectomy, but is accompanied by considerable toxicity by collateral destruction of normal cells. Such side effects may be avoided by developing therapies that specifically target molecular characteristics of tumors. The aim of the present study was to determine the proportion of esophageal squamous cell carcinoma (ESCC) patients that could possibly benefit from (a combination of) currently available targeted therapies, by assessing the frequency of immunohistochemical expression of their target molecular markers in ESCC tissues. Sections from a validated tissue microarray comprising 108 ESCCs were immunohistochemically stained for Bcl-2, c-KIT, cyclo-oxygenase-2 (COX-2), cyclin D1, estrogen receptor (ER), epidermal growth factor receptor (EGFR), Her-2/neu, progesterone receptor (PR), and vascular endothelial growth factor (VEGF). VEGF, cyclin D1, EGFR, and COX-2 could be detected in 55, 42, 40, and 40%, respectively. Her-2/neu, Bcl-2, and c-KIT were detected in 12, 11, and 10% of the tumors, respectively. No nuclear expression of ER or PR was noticed. Concurrent expression of two markers was noticed in 28% of ESCCs, whereas 25% of ESCCs showed concurrent expression of three markers. The concurrent expression of two of the most frequently expressed markers (VEGF, cyclin D1, EGFR, and COX-2) ranged from 11 (COX-2 and EGFR) to 26% (cyclin D1 and VEGF). The expression of all of these four markers was seen in 5% of ESCCs. Promising targets for molecular therapy in ESCC appear to be COX-2, VEGF, EGFR, and cyclin D1, as they are frequently overexpressed. Phase II clinical studies on these molecular markers may therefore be warranted. The role for targeted therapy against ER, PR, Her-2/neu, c-KIT, or Bcl-2 in ESCC seems limited.

Risk factors and gene expression in esophageal cancer

Esophageal cancer is a significant worldwide health problem because of its poor prognosis and high incidence in certain parts of the world. Tobacco smoke and alcohol consumption are significant risk factors for esophageal squamous cell carcinoma, whereas frequent gastroesophageal reflux and subsequent inflammatory reactions play a role in causing the adenocarcinoma. Esophageal carcinogenesis involves multiple genetic alterations. A large body of knowledge has been generated regarding molecular alterations associated with esophageal carcinogenesis. These alterations include aberrant cell cycle control, DNA repair, cellular enzymes, growth factor receptors, and nuclear receptors. This chapter reviews the most frequent gene alterations and their correlation with risk factors as well as the prevention strategies in esophageal cancer.

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.

Synergistic inhibition of head and neck tumor growth by green tea (-)-epigallocatechin-3-gallate and EGFR tyrosine kinase inhibitor

One of the mechanisms of the antitumor activity of green tea (-)-epigallocatechin-3-gallate (EGCG) is associated with its effect on epidermal growth factor receptor (EGFR)-mediated signaling transduction pathways. We investigated whether combining EGCG with the EGFR-tyrosine kinase inhibitor (EGFR-TKI) erlotinib may augment erlotinib-induced cell growth inhibition of squamous cell carcinoma of the head and neck (SCCHN) in a mouse xenograft model. In vitro studies with 5 head and neck cancer cell lines revealed that synergistic cell growth inhibition by the combination of EGCG and erlotinib was associated with significantly greater inhibition of pEGFR and pAKT, increased activation of caspases 9, 3 and PARP compared to the inhibition induced by EGCG or erlotinib alone. Erlotinib inhibited phosphorylation of EGFR, stabilizing EGFR at the plasma membrane, whereas EGCG induced EGFR internalization and ubiquitin-degradation, ultimately undermining EGFR signaling. The efficacy of the combination treatment was investigated with nude mice (n = 25) orally gavaged with vehicle control, EGCG, erlotinib or the combination at the same doses for 7 days, followed by subcutaneous injection with Tu212 cells. Animals were continuously administered the agents 5 days weekly for 7 weeks. The combined treatment resulted in significantly greater inhibition of tumor growth and delayed tumor progression as a result of increased apoptosis, decreased cell proliferation and reduced pEGFR and pAKT compared to the single agent treatment groups. Our results suggest a synergistic antitumor effect of a combined treatment with EGCG and erlotinib, and provide a promising regimen for future chemoprevention and treatment of SCCHN.

Protein alterations in ESCC and clinical implications: a review

Esophageal squamous cell carcinoma (ESCC) is the predominant histological subtype of esophageal cancer in Asia, characterized by high incidence and mortality rate. Although significant progress has been made in surgery and adjuvant chemoradiotherapy, the prognosis of the patients with this cancer still remains poor. Investigation into protein alterations that occurred in tumors can provide clues to discover new biomarkers for improving diagnosis and guiding targeted therapy. Hundreds of papers have appeared over the past several decades concerning protein alterations in ESCC. This review summarizes all the dysregulated proteins investigated in the disease from 187 published papers and analyzes their contributions to tumor development and progression. We document protein alterations associated with tumor metastasis and the transition from normal esophageal epithelia to dysplasia in order to reveal the most useful markers for prediction of clinical outcome, early detection, and identification of high-risk patients for targeted therapies. In particular, we discuss the largest and most rigorous studies on prognostic implications of proteins in ESCC, in which cyclin D1, p53, E-cadherin and VEGF appeared to have the strongest evidence as independent predictors of patient outcome.

Epidermal growth factor receptor-directed therapy in esophageal cancer

Esophageal adenocarcinoma (EAC) is one of the fastest growing malignancies in the US. The long-term survival of patients with this cancer remains poor; only 25% of patients undergoing surgical excision are alive after 5 years. Multimodal programs that incorporate radiotherapy, chemotherapy and surgery for localized tumors may result in a modest survival advantage. However, significant strides in this disease can result from the inclusion of targeted therapies. The epidermal growth factor receptor (EGFR) family represents one such target and is receiving increasing attention due to the advent of specific inhibitors. Studies conducted by us and others have shown that the overexpression of EGFR family signaling intermediates is common in Barrett's esophagus and EAC. In the latter case, EGFR expression may have prognostic significance. EGFR inhibitors, including oral tyrosine kinase inhibitors and monoclonal antibodies, result in a synergistic antitumor effect with chemotherapeutic agents or with radiotherapy. Therefore, several ongoing studies include EGFR-directed therapy either alone or in combination with chemoradiotherapy for this disease. Our study of gefitinib, oxaliplatin and radiotherapy suggested that gefitinib can be safely incorporated into an oxaliplatin-based chemoradiation program for esophageal cancer, although the clinical activity of this combination is modest. Herein, we review the current literature on this subject.

Pilot study of neoadjuvant treatment with erlotinib in nonmetastatic head and neck squamous cell carcinoma

PURPOSE

To determine the safety and efficacy of erlotinib given as neoadjuvant treatment in patients with head and neck squamous cell carcinoma (HNSCC). Further objectives were to identify markers of response to erlotinib and to assess the pharmacodynamic effects of erlotinib in tumor cells.

EXPERIMENTAL DESIGN

Patients with locally advanced nonmetastatic HNSCC were treated with erlotinib 150 mg daily pending surgical management. Tumor samples were collected before and after erlotinib treatment and were analyzed using immunohistochemistry. Epidermal growth factor receptor copy number was determined in tumors using CISH analysis.

RESULTS

Between November 2003 and December 2005, 35 patients were included in the study. Neoadjuvant treatment with erlotinib in HNSCC patients was well tolerated and did not necessitate modification to routine surgical procedures. Among 31 evaluable patients, erlotinib was given for a median of 20 days. At the time of surgery, tumor shrinkage was observed in nine patients (29%). Immunohistochemistry analyses were done for 31 patients and showed a decrease in phosphorylated tyrosine residues and phosphorylated erk immunostaining after erlotinib treatment. In a retrospective analysis, baseline p21(waf) expression in the basal-like cell layer was statistically positively correlated with clinical response to treatment. Epidermal growth factor receptor copy number did not correlate with response to erlotinib.

CONCLUSION

Neoadjuvant treatment of HNSCC with erlotinib was well tolerated. Baseline p21(waf) expression was associated with response to erlotinib and so might be useful as a tool to select patients for erlotinib therapy in this setting.

Treatment of gastrointestinal neuroendocrine tumors with inhibitors of growth factor receptors and their signaling pathways: recent advances and future perspectives

The limited efficacy of conventional cytotoxic treatment regimes for advanced gastrointestinal neuroendocrine cancers emphasizes the need for novel and more effective medical treatment options. Recent findings on the specific biological features of this family of neoplasms has led to the development of new targeted therapies, which take into account the high vascularization and abundant expression of specific growth factors and cognate tyrosine kinase receptors. This review will briefly summarize the status and future perspectives of antiangiogenic, mTOR- or growth factor receptor-based pharmacological approaches for the innovative treatment of gastrointestinal neuroendocrine tumors. In view of the multitude of novel targeted approaches, the rationale for innovative combination therapies, i.e. combining growth factor (receptor)-targeting agents with chemo- or biotherapeutics or with other novel anticancer drugs such as HDAC or proteasome inhibitors will be taken into account.

Immunohistochemical examination of gastrin, gastrin precursors, and gastrin/CCK-2 receptor in human esophageal squamous cell carcinomas

A promoting effect of gastrin on stimulating Barrett's oesophagus proliferation has been demonstrated, but whether it plays a regulating role for esophageal squamous cell carcinoma (ESCC) to date has not been fully investigated. The aim of this study is to examine the expressions of gastrin, gastrin precursors and gastrin/CCK-2 receptor in ESCC. Tissue specimen sections from 38 patients with ESSC obtained from a high incidence area of north China were assessed using immunohistochemistry for amidated gastrin, gastrin precursors (progastrin and glycine-extended gastrin) and gastrin/CCK-2 receptors. Their clinical histopathological significance was also analyzed. Of 38 ESCC, the immunoreactivities of gastrin, glycine-extended gastrin and progastrin were observed in 13.2% (5/38), 7.9% (3/38) and 23.68% (9/38) cases. The expression of progastrin was obviously higher than other gastrins, though not significantly (P > 0.05). In positive cases for gastrin or glycine-extended gastrin, the scores of positive tumor cell numbers were at a lower density (<10/abundant-distributed field). However, the scores of progastrin positive tumor cell density in five of nine positive cases were over 10/abundant-distributed field. The immunoreactivity of gastrin/CCK-2 receptor was also observed in 15.8% (6/38) ESCC cases. There was not significant correlation regarding immunohistochemical results with known histomorphological parameters i.e. gender, tumor location and TNM stages. Based on our current results, ESCC tumor cells could be a possible cellular source of gastrin precursors, which has been postulated to play a role in regulating the growth in some human tumor cells.

Angiopoietin-1 targeted RNA interference suppresses angiogenesis and tumor growth of esophageal cancer

AIM: To determine the inhibitory effect of the adenovirus-based angiopoietin-1 (Ang-1) targeted small interfering RNA expression system (Ad/Ang-1si) on the expression of the Ang-1 gene, cell growth and apoptosis in human esophageal cancer cell line Eca109.

METHODS: siRNA-expressing adenovirus targeting Ang-1 gene was constructed using the Ad Easy System. Cultured Eca109 cells were transfected with Ad/Ang-1si (Eca109/Ang-1si), and Ad/si was used to infect Eca109 cells as control (Eca109/si). Ang-1 gene expression and concentration was determined with RT-PCR and ELISA, respectively. Human umbilical vein endothelial cell (HUVEC) migration and proliferation were analyzed. After s.c. injection into athymic nu/nu mice, the tumor growth, vessel density and apoptosis of each group was also determined.

RESULTS: HUVEC migration induced by conditioned medium from Ang-1si-transfected Eca109 cells was significantly less than that induced by conditioned medium from Eca109 cells and control adenovirus-transfected Eca109 cells. Furthermore, after s.c. injection into athymic nu/nu mice, the tumor growth and cell apoptosis of Ad/Ang-1si -expressing Eca109 cells was significantly lower than that of parental or control adenovirus-transfected cells. Vessel density assessed by CD31 immunohistochemical analysis and Ang-1 expression by RT-PCR were also decreased.

CONCLUSION: The targeting Ang-1 may provide a therapeutic option for esophageal cancer.

Combined targeting of epidermal growth factor receptor, signal transducer and activator of transcription-3, and Bcl-X(L) enhances antitumor effects in squamous cell carcinoma of the head and neck

Squamous cell carcinoma of the head and neck (SCCHN) is a leading cause of cancer deaths worldwide. Epidermal growth factor receptor (EGFR), an upstream mediator of signal transducer and activator of transcription (STAT)-3 is overexpressed in a variety of cancers, including SCCHN. Therapies such as monoclonal antibodies and tyrosine kinase inhibitors targeting EGFR have demonstrated limited antitumor efficacy, which may be explained, in part, by persistent STAT3 activation despite EGFR inhibition. STAT3 activation induces expression of target genes in SCCHN, including Bcl-X(L), a mediator of antiapoptotic activity. Bcl-X(L) is commonly overexpressed in SCCHN where it correlates with chemoresistance, making it a potential therapeutic target. Targeting the EGFR-STAT3-Bcl-X(L) pathway at several levels, including the upstream receptor, the intracellular transcription factor, and the downstream target gene, has not been investigated previously. Using erlotinib, an EGFR-specific reversible tyrosine kinase inhibitor in combination with a STAT3 transcription factor decoy, we found enhanced antitumor effects in vitro and in vivo. The combination of the STAT3 decoy and gossypol, a small molecule targeting Bcl-X(L), also yielded enhanced inhibition of cell proliferation. The triple combination of erlotinib, STAT3 decoy, and gossypol further enhanced cell growth inhibition and apoptosis in vitro, and it down-regulated signaling molecules further downstream of the EGFR-STAT3 signaling pathway, such as cyclin D1. These results suggest that combined targeting of several components of an oncogenic signaling pathway may be an effective therapeutic strategy for SCCHN.

Bypassing cellular EGF receptor dependence through epithelial-to-mesenchymal-like transitions

Over 90% of all cancers are carcinomas, malignancies derived from cells of epithelial origin. As carcinomas progress, these tumors may lose epithelial morphology and acquire mesenchymal characteristics which contribute to metastatic potential. An epithelial-to-mesenchymal transition (EMT) similar to the process critical for embryonic development is thought to be an important mechanism for promoting cancer invasion and metastasis. Epithelial-to-mesenchymal transitions have been induced in vitro by transient or unregulated activation of receptor tyrosine kinase signaling pathways, oncogene signaling and disruption of homotypic cell adhesion. These cellular models attempt to mimic the complexity of human carcinomas which respond to autocrine and paracrine signals from both the tumor and its microenvironment. Activation of the epidermal growth factor receptor (EGFR) has been implicated in the neoplastic transformation of solid tumors and overexpression of EGFR has been shown to correlate with poor survival. Notably, epithelial tumor cells have been shown to be significantly more sensitive to EGFR inhibitors than tumor cells which have undergone an EMT-like transition and acquired mesenchymal characteristics, including non-small cell lung (NSCLC), head and neck (HN), bladder, colorectal, pancreas and breast carcinomas. EGFR blockade has also been shown to inhibit cellular migration, suggesting a role for EGFR inhibitors in the control of metastasis. The interaction between EGFR and the multiple signaling nodes which regulate EMT suggest that the combination of an EGFR inhibitor and other molecular targeted agents may offer a novel approach to controlling metastasis.

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.