Heparin-binding EGF-like growth factor is an early response gene to chemotherapy and contributes to chemotherapy resistance

Adaptive resistance to lorlatinib via EGFR signaling in ALK-rearranged lung cancer

Anaplastic lymphoma kinase (ALK)-tyrosine kinase inhibitors rarely elicit complete responses in patients with advanced ALK-rearranged non-small cell lung cancer (NSCLC), as a small population of tumor cells survives due to adaptive resistance. Therefore, we focused on the mechanisms underlying adaptive resistance to lorlatinib and therapeutic strategies required to overcome them. We found that epidermal growth factor receptor (EGFR) signaling was involved in the adaptive resistance to lorlatinib in ALK-rearranged NSCLC, activation of which was induced by heparin-binding EGF-like growth factor production via c-Jun activation. EGFR inhibition halted ALK-rearranged lung cancer cell proliferation by enhancing ALK inhibition-induced apoptosis via suppression of Bcl-xL. Xenograft models showed that the combination of EGFR inhibitor and lorlatinib considerably suppressed tumor regrowth following cessation of these treatments. This study provides new insights regarding tumor evolution due to EGFR signaling after lorlatinib treatment and the development of combined therapeutic strategies for ALK-rearranged lung cancer.

The Role of Membrane-Type 1 Matrix Metalloproteinase-Substrate Interactions in Pathogenesis

A protease is an enzyme with a proteolytic activity that facilitates the digestion of its substrates. Membrane-type I matrix metalloproteinase (MT1-MMP), a member of the broader matrix metalloproteinases (MMP) family, is involved in the regulation of diverse cellular activities. MT1-MMP is a very well-known enzyme as an activator of pro-MMP-2 and two collagenases, MMP-8 and MMP-13, all of which are essential for cell migration. As an anchored membrane enzyme, MT1-MMP has the ability to interact with a diverse group of molecules, including proteins that are not part of the extracellular matrix (ECM). Therefore, MT1-MMP can regulate various cellular activities not only by changing the extra-cellular environment but also by regulating cell signaling. The presence of both intracellular and extra-cellular portions of MT1-MMP can allow it to interact with proteins on both sides of the cell membrane. Here, we reviewed the MT1-MMP substrates involved in disease pathogenesis.

Aloysia Citrodora Essential Oil Inhibits Melanoma Cell Growth and Migration by Targeting HB-EGF-EGFR Signaling

Patients diagnosed with melanoma have a poor prognosis due to regional invasion and metastases. The receptor tyrosine kinase epidermal growth factor receptor (EGFR) is found in a subtype of melanoma with a poor prognosis and contributes to drug resistance. Aloysia citrodora essential oil (ALOC-EO) possesses an antitumor effect. Understanding signaling pathways that contribute to the antitumor of ALOC-EO is important to identify novel tumor types that can be targeted by ALOC-EO. Here, we investigated the effects of ALOC-EO on melanoma growth and tumor cell migration. ALOC-EO blocked melanoma growth in vitro and impaired primary tumor cell growth in vivo. Mechanistically, ALOC-EO blocked heparin-binding-epidermal growth factor (HB-EGF)-induced EGFR signaling and suppressed ERK1/2 phosphorylation. Myelosuppressive drugs upregulated HB-EGF and EGFR expression in melanoma cells. Cotreatment of myelosuppressive drugs with ALOC-EO improved the antitumor activity and inhibited the expression of matrix metalloproteinase-7 and -9 and a disintegrin and metalloproteinase domain-containing protein9. In summary, our study demonstrates that ALOC-EO blocks EGFR and ERK1/2 signaling, with preclinical efficacy as a monotherapy or in combination with myelosuppressive drugs in melanoma.

E6-mediated activation of JNK drives EGFR signalling to promote proliferation and viral oncoprotein expression in cervical cancer

Human papillomaviruses (HPV) are a major cause of malignancy worldwide, contributing to ~5% of all human cancers including almost all cases of cervical cancer and a growing number of ano-genital and oral cancers. HPV-induced malignancy is primarily driven by the viral oncogenes, E6 and E7, which manipulate host cellular pathways to increase cell proliferation and enhance cell survival, ultimately predisposing infected cells to malignant transformation. Consequently, a more detailed understanding of viral-host interactions in HPV-associated disease offers the potential to identify novel therapeutic targets. Here, we identify that the c-Jun N-terminal kinase (JNK) signalling pathway is activated in cervical disease and in cervical cancer. The HPV E6 oncogene induces JNK1/2 phosphorylation in a manner that requires the E6 PDZ binding motif. We show that blockade of JNK1/2 signalling using small molecule inhibitors, or knockdown of the canonical JNK substrate c-Jun, reduces cell proliferation and induces apoptosis in cervical cancer cells. We further demonstrate that this phenotype is at least partially driven by JNK-dependent activation of EGFR signalling via increased expression of EGFR and the EGFR ligands EGF and HB-EGF. JNK/c-Jun signalling promoted the invasive potential of cervical cancer cells and was required for the expression of the epithelial to mesenchymal transition (EMT)-associated transcription factor Slug and the mesenchymal marker Vimentin. Furthermore, JNK/c-Jun signalling is required for the constitutive expression of HPV E6 and E7, which are essential for cervical cancer cell growth and survival. Together, these data demonstrate a positive feedback loop between the EGFR signalling pathway and HPV E6/E7 expression, identifying a regulatory mechanism in which HPV drives EGFR signalling to promote proliferation, survival and EMT. Thus, our study has identified a novel therapeutic target that may be beneficial for the treatment of cervical cancer.

Peptides derived from a short stretch of diphtheria toxin bind to heparin-binding epidermal growth factor-like growth factor

Membrane-anchored heparin-binding EGF-like growth factor (HB-EGF) is the receptor for diphtheria toxin (DT). Mutated or truncated, non-toxic DT has been used earlier for HB-EGF-targeted drug delivery and to modulate HB-EGF signaling. In the present work, we have synthesized a peptide corresponding to a 26 amino acid long stretch of the receptor-binding domain of DT. This region of DT makes multiple contacts with HB-EGF and has residues critical for binding to HB-EGF. We show that this peptide and two of its mutants bind to HB-EGF. We have also created recombinant proteins by fusing Maltose-binding Protein (MBP) with these peptides. These recombinant MBP-tagged peptides bind to HB-EGF with affinities in the range of 10^-7 to 10^-8 M. We have observed that these MBP-tagged peptides can modulate molecular signaling of HB-EGF. Therefore, this 26 amino acid long stretch of DT can be considered as an independent functional segment for binding to HB-EGF. Peptides corresponding to this region may be used for HB-EGF targeted cellular delivery of molecular cargo or to modulate HB-EGF signaling.

First-in-human study of the anti-HB-EGF antibody U3-1565 in subjects with advanced solid tumors

U3-1565 is a monoclonal antibody directed against heparin-binding epidermal growth factor-like growth factor (HB-EGF), which mediates angiogenesis via induction of vascular endothelial growth factor (VEGF-A). This first-in-human study characterized the safety, tolerability, efficacy, pharmacokinetics, and pharmacodynamics of U3-1565 in subjects with advanced solid tumors. In Part 1 (dose escalation following a modified 3 + 3 design), Cohorts 1-4, U3-1565 was administered at 2, 8, 16, and 24 mg/kg every 3 weeks for Cycle 1 and every 2 weeks thereafter. In Part 1, Cohort 5, and in Part 2 (dose expansion), U3-1565 was administered at 24 mg/kg every week. Thirty-six subjects were enrolled and treated (15 in Part 1; 21 in Part 2). No subject experienced dose limiting toxicity and maximum tolerated dose was not reached. All drug-related events were Grade 1 or 2 in severity, with fatigue and rash predominating. Following treatment with U3-1565, 1 subject with metastatic colorectal cancer experienced partial response and 6 subjects achieved stable disease. Four subjects completed the study main phase (first 12 cycles) and entered the extension phase. Of the 6/36 subjects with high (> 1500 pg/ml) baseline VEGF-A levels, all showed a decrease in VEGF-A (median - 60% [-22% to -97%]). Of the remaining subjects, only 19/30 showed a decrease (median - 18% [-2% to -82%]). Subjects with high VEGF-A baseline levels remained on treatment longer (3/6 entered study extension phase versus 1/30), and were more likely to show disease control (3/6 versus 4/30). In conclusion, U3-1565 demonstrates both proof of mechanism and clinical activity across different tumor types.

Phase 1 Study of Monotherapy with KHK2866, an Anti-Heparin-Binding Epidermal Growth Factor-Like Growth Factor Monoclonal Antibody, in Patients with Advanced Cancer

BACKGROUND

KHK2866 is a recombinant, humanized, non-fucosylated, monoclonal antibody directed at heparin-binding epidermal growth factor-like growth factor (HB-EGF).

OBJECTIVE

To determine the safety, tolerability, maximum tolerated dose (MTD), pharmacokinetics, pharmacodynamics, potential immunogenicity, and preliminary clinical efficacy of KHK2866 monotherapy in patients with advanced and refractory cancer in a first-in-human, phase 1 study.

MATERIALS AND METHODS

Using a standard 3 + 3 dose-escalation design, 20 patients received KHK2866 (0.3, 1, and 3 mg/kg) intravenously once weekly. Two additional patients received 0.1 mg/kg in a cohort which was subsequently added following protocol amendment.

RESULTS

The first three patients enrolled experienced grade 2 hypersensitivity (acute infusion reactions) after the first dose of KHK2866. After prophylactic treatment with an H1-blocker and corticosteroids in subsequently recruited patients, two grade 2 hypersensitivity reactions were observed in the remaining 19 patients. Grade 2/3 neurotoxicity appeared to be dose-limiting at 3 mg/kg in the original dose-escalation cohorts (n = 2), at 1 mg/kg in the MTD dose expansion cohort (n = 1), and at 0.1 mg/kg (n = 1). Neurotoxicity was manifested as complex partial seizure activity, aphasia, and confusion after first-dose administration. Pharmacokinetic exposure to KHK2866 increased proportionally to dose. Mean elimination half-life was 71.9-118 h over the dose range from 0.3 to 3 mg/kg. All KHK2866 doses decreased serum free HB-EGF levels, generally below the lower limit of quantification.

CONCLUSIONS

The study was terminated because of neuropsychiatric toxicity. The only predictive factor for neuropsychiatric toxicity was administration of KHK2866. These effects were reversible, but were not predictable. Their etiology is not presently understood. [Study registered at ClinicalTrials.gov #NCT0179291].

HB-EGF is associated with DNA damage and Mcl-1 turnover in human glioma cell lines treated by Temozolomide

Temozolomide (TMZ) is the main chemotherapeutic agent used for treating newly diagnosed Glioblastoma Multiforme (GBM), the most frequent malignant brain tumors in adults. This alkylating agent induces DNA double strand breaks (DSBs) which in turn lead to apoptosis by activating the Bcl-2 controlled mitochondrial pathway. However, GBM invariably recur as tumors become resistant to TMZ. We investigated the implication of EGFR ligands in this resistance and we found that the pro Heparin Binding Epidermal Growth Factor (proHB-EGF) expression is linked to the early response to TMZ in human glioma cell lines. However, HB-EGF does not affect apoptosis per se although its expression is associated with the degradation of Mcl-1. HB-EGF is implicated in DSBs repair as silencing of HB-EGF increased γH2AX foci half-life as well as USP9X expression, two features that could be linked to the observed effect on Mcl-1. Our data demonstrate a new role for HB-EGF in TMZ treated cell lines.

Gene signatures associated with drug resistance to irinotecan and oxaliplatin predict a poor prognosis in patients with colorectal cancer

The identification of novel survival predictors may help to improve the appropriate management of colorectal cancer (CRC). In the present study, two gene sets associated with irinotecan or oxaliplatin resistance in CRC cell lines were first identified and subsequently applied to the clinical CRC microarray dataset GSE14333. Subsequently, a 60-gene irinotecan resistance-associated signature and a 13-gene oxaliplatin resistance-associated signature were established, which were able to classify CRC patients into high- and low-risk subgroups with varied clinical outcomes [irinotecan-resistance gene signature: hazard ratio (HR)=0.4607, 95% confidence interval (CI)=0.3369-0.6300, P<0.0001; oxaliplatin-resistance gene signature: HR=0.6119, 95% CI=0.4547-0.8233, P=0.0008]. The performance of these two gene expression signatures in predicting outcome risk were also validated in two other independent CRC gene expression microarray datasets, GSE17536 (irinotecan-resistance gene signature: HR=0.5318, 95% CI=0.3359-0.8419, P=0.0079; oxaliplatin-resistance gene signature: HR=0.5383, 95% CI=0.3400-0.8521, P=0.0114) and GSE17537 (irinotecan-resistance gene signature: HR=0.2827, 95% CI=0.1173-0.6813, P=0.0088; oxaliplatin-resistance gene signature: HR=0.2378, 95% CI=0.09773-0.5784, P=0.0023). Furthermore, the combination of these two gene classifiers demonstrated a superior performance in CRC prognosis prediction than either used individually. Therefore, this study proposed novel gene classifier models for CRC prognosis prediction, which may be potentially useful to inform treatment decisions for patients with CRC in clinical settings.

BK-UM in patients with recurrent ovarian cancer or peritoneal cancer: a first-in-human phase-I study

Background

BK-UM (CRM197) is a mutant form of diphtheria toxin and a specific inhibitor of heparin-binding epidermal growth factor-like growth factor (HB-EGF). We assessed the safety, pharmacokinetics, recommended dose, and efficacy of BK-UM in patients with recurrent ovarian cancer (OC) or peritoneal cancer (PC), and measured HB-EGF levels in serum and abdominal fluid after BK-UM administration.

Methods

Eleven patients with advanced or recurrent OC or PC were enrolled and treated with BK-UM via the intraperitoneal route. The dose was escalated (1.0, 2.0, 3.3, and 5.0 mg/m²) using a 3 + 3 design.

Results

Eight of 11 patients completed treatment. No dose-limiting toxicity (DLT) was experienced at dose levels 1 (1.0 mg/m²) and 2 (2.0 mg/m²). Grade 3 transient hypotension as an adverse event (defined as a DLT in the present study) was observed in two of four patients at dose level 3 (3.3 mg/m²). Treatment with BK-UM was associated with decreases in HB-EGF levels in serum and abdominal fluid in seven of 11 patients and five of eight patients, respectively. Clinical outcomes included a partial response in one patient, stable disease in five patients, and progressive disease in five patients.

Conclusions

BK-UM was well tolerated at doses of 1.0 and 2.0 mg/m², with evidence for clinical efficacy in patients with recurrent OC or PC. A dose of 2.0 mg/m² BK-UM is recommended for subsequent clinical trials.

Trial registration

This trial was prospectively performed as an investigator-initiated clinical trial. The trial numbers are UMIN000001002 and UMIN000001001, with registration dates of 1/30/2008 and 2/4/2008, respectively. UMIN000001001 was registered as a trial for the continuous administration of BK-UM after UMIN000001002.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3071-5) contains supplementary material, which is available to authorized users.

Receptor-Mediated Enhanced Cellular Delivery of Nanoparticles Using Recombinant Receptor-Binding Domain of Diphtheria Toxin

Antibodies and peptides are often used to home nanoparticles (NPs) to specific cells. Here in this work, we have used recombinant receptor-binding domain of diphtheria toxin (RDT) as a homing molecule for NPs. Diphtheria toxin binds to heparin binding EGF-like growth factor (HB-EGF) through its receptor-binding domain. HB-EGF is often overexpressed as cell surface molecule in various types of cancer. We have prepared monodispersed, spherical PLGA NPs and coated these NPs with RDT. These NPs are characterized by FESEM and FT-IR spectroscopy. Using flow cytometry and fluorescence spectroscopy, we show that coating with RDT increases cellular uptake of PLGA NPs. We further show that RDT-coated nanoparticles are internalized through clathrin-dependent receptor-mediated endocytosis that can be reduced by specific inhibitor. These RDT-coated nanoparticles (RDT-NP) were further used for preferential delivery of Irinotecan, a chemotherapeutic agent, to cells overexpressing HB-EGF. We show that receptor-mediated enhanced uptake of RDT-NPs increases the potency of irinotecan in these cells.

Therapeutic targets and new directions for antibodies developed for ovarian cancer

Antibody therapeutics against different target antigens are widely used in the treatment of different malignancies including ovarian carcinomas, but this disease still requires more effective agents. Improved understanding of the biological features, signaling pathways, and immunological escape mechanisms involved in ovarian cancer has emerged in the past few years. These advances, including an appreciation of the cross-talk between cancer cells and the patient's immune system, have led to the identification of new targets. In turn, potential antibody treatments with various mechanisms of action, including immune activation or toxin-delivery, that are directed at these targets have been developed. Here, we identify established as well as novel targets for antibodies in ovarian cancer, and discuss how they may provide fresh opportunities to identify interventions with enhanced therapeutic potential.

miRNAs: mediators of ErbB family targeted therapy resistance

The ErbB/HER tyrosine kinase receptors family plays a key regulatory role in different cellular processes by activating several signaling pathways. In different tumor types, mutations or overexpression of the ErbB family members are a common feature, which led to the development of targeted therapies against this receptors. Although with this kind of treatment we are heading to a more personalized medicine, the development of acquired resistance is still an issue, therefore, several studies focused on discovering the mechanisms behind it. More recently, miRNAs have been described as important mediators of acquired resistance, specifically, acquired resistance to ErbB family targeted therapies. Ultimately, miRNA-based therapeutics using exosomes as a drug delivery model can revolutionize today's approach of cancer treatment.

Cross-reacting material 197, a heparin-binding EGF-like growth factor inhibitor, reverses the chemoresistance in human cisplatin-resistant ovarian cancer

Cross-reacting material 197 (CRM197), a specific HB-EGF inhibitor, has been proven to be a promising antitumor agent for ovarian cancer therapy. Our previous studies have shown that CRM197 has potent antitumor activity in human cisplatin-resistant ovarian cancer. However, the relationship between CRM197 and the resistance to cisplatin remains unclear. Here, we report that CRM197 significantly reverses the resistance to cisplatin in cisplatin-resistant ovarian carcinoma cell line (A2780/CDDP). We established xenograft nude mice models with A2780 and A2780/CDDP cells. Notably, we observed that CRM197 suppresses the expression of HB-EGF and epidermal growth factor receptor in A2780/CDDP cells and xenografts harboring the overexpression of HB-EGF and epidermal growth factor receptor. Experiments conducted in vitro and in vivo suggest that CRM197 markedly downregulates the expression of excision repair cross-complementing group 1 (P = 0.002) and DNA repair capacity in A2780/CDDP tumor (P < 0.001) by inactivation of extracellular signal-regulated kinase signaling, providing novel possible mechanisms for the ability of CRM197 to restore drug sensitivity. These results suggest that CRM197 as an HB-EGF inhibitor might be a cisplatin-chemosensitizing agent for the treatment of ovarian carcinoma with resistance to cisplatin.

Characterization of a Novel Anti-Human HB-EGF Monoclonal Antibody Applicable for Paraffin-Embedded Tissues and Diagnosis of HB-EGF-Related Cancers

Heparin-binding EGF-like growth factor (HB-EGF) is a member of the EGF family of growth factors that bind to and activate the EGF receptor (EGFR/ErbB1) and ErbB4. HB-EGF plays pivotal roles in pathophysiological processes, including cancer. Thus, monoclonal antibodies (mAbs) for HB-EGF detection could be an important tool in the therapeutic diagnosis of HB-EGF-related cancers and other diseases. However, few mAbs, especially those applicable for immunohistochemistry (IHC), have been established to date. In this study, we generated a clone of hybridoma-derived mAb 2-108 by immunizing mice with recombinant human HB-EGF protein expressed by human cells. The mAb 2-108 specifically bound to human HB-EGF but not to mouse HB-EGF and was successful in immunoblotting, even under reducing conditions, immunoprecipitation, and immunofluorescence for unfixed as well as paraformaldehyde-fixed cells. Notably, this mAb was effective in IHC of paraffin-embedded tumor specimens. Epitope mapping analysis showed that mAb 2-108 recognized the N-terminal prodomain in HB-EGF. These results indicate that this new anti-HB-EGF mAb 2-108 would be useful in the diagnosis of HB-EGF-related cancers and would be a strong tool in both basic and clinical research on HB-EGF.

Cross-reacting material 197 reverses the resistance to paclitaxel in paclitaxel-resistant human ovarian cancer

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) has been proven to be a promising chemotherapeutic target for ovarian cancer. Our previous studies have demonstrated that inhibition of HB-EGF by the special inhibitor, cross-reacting material 197 (CRM197), potently inhibits the anti-tumor activity in paclitaxel-resistant ovarian cancer. Here, we found that inhibition of HB-EGF by CRM197 significantly reverses the resistance to paclitaxel in paclitaxel-resistant ovarian carcinoma cell line (A2780/Taxol). A2780/Taxol cells over-expressed HB-EGF and epidermal growth factor receptor (EGFR) and CRM197 notably suppressed the expression of HB-EGF and EGFR. Experiments performed in vitro and in vivo further suggested that CRM197 markedly down-regulated the ATP-binding cassette sub-family B member 1 (ABCB1/MDR1) messenger RNA (mRNA) expression (P = 0.01), plasma membrane glycoprotein (P-gp) protein (P = 0.009), and P-gp-mediated efflux (P = 0.007) through inhibition of nuclear factor-κB (NF-κB) expression, which were classical chemoresistance-related targets with respect to paclitaxel therapy. Meanwhile, inhibition of HB-EGF enhanced caspase-3 activity to induce apoptosis via MDR1 inhibition in A2780/Taxol cells (P = 0.038). Collectively, HB-EGF is a molecular target for the resistance of ovarian cancer to paclitaxel and CRM197 as a HB-EGF-targeted agent might be a chemosensitizing agent for paclitaxel-resistant ovarian carcinoma. Our findings provide novel possible mechanisms for HB-EGF to be a target to restore the chemosensitivity to paclitaxel.

Identification of diphtheria toxin R domain mutants with enhanced inhibitory activity against HB-EGF

Heparin-binding epidermal growth factor-like growth factor (HB-EGF), a ligand of EGF receptor, is involved in the growth and malignant progression of cancers. Cross-reacting material 197, CRM197, a non-toxic mutant of diphtheria toxin (DT), specifically binds to the EGF-like domain of HB-EGF and inhibits its mitogenic activity, thus CRM197 is currently under evaluation in clinical trials for cancer therapy. To develop more potent DT mutants than CRM197, we screened various mutant proteins of R domain of DT, the binding site for HB-EGF. A variety of R-domain mutant proteins fused with maltose-binding protein were produced and their inhibitory activity was evaluated in vitro. We found four R domain mutants that showed much higher inhibitory activity against HB-EGF than wild-type (WT) R domain. These R domain mutants suppressed HB-EGF-dependent cell proliferation more effectively than WT R domain. Surface plasmon resonance revealed their higher affinity to HB-EGF than WT R domain. CRM197(R460H) carrying the newly identified mutation showed increased cell proliferation inhibitory activity and affinity to HB-EGF. These results suggest that CRM197(R460H) or other recombinant proteins carrying newly identified mutation(s) in the R domain are potential therapeutics targeting HB-EGF.

Triple-negative breast cancer: investigating potential molecular therapeutic target

INTRODUCTION

Triple-negative breast cancer (TNBC) makes up about 10 - 20% of all breast cancers and the lack of hormone receptors and human epidermal growth factor receptor-2/Neu expression is responsible for poor prognosis, no targeted therapies and trouble in the clinical management. Tumor heterogeneity, also within the same tumor, is a major cause for this difficulty. Based on the introduction of new biological drugs against different kinds of tumor, many efforts have been made for classification of genetic alterations present in TNBC, leading to the identification of several oncogenes and tumor suppressor genes involved in breast cancer carcinogenesis.

AREAS COVERED

In this review we investigated the molecular alteration present in TNBC which could lead to the creation of new targeted therapies in the future, with the aim to counteract this disease in the most effective way.

EXPERT OPINION

In this context some hormone receptors like G-protein-coupled receptor 30 and androgen receptors may be a fascinating area to investigate; also, angiogenesis, represented not only by the classical VEGF/VEGFR relationship, but also by other molecules, like semaphorins, fibroblast growth factor and heparin-binding-EGF-like, is a mechanism in which new developments are expected. In this perspective, one technique that may show promise is the gene therapy; in particular the gene transfer could correct abnormal genetic function in cancer cells.

Contribution of transcription factor, SP1, to the promotion of HB-EGF expression in defense mechanism against the treatment of irinotecan in ovarian clear cell carcinoma

Ovarian clear cell carcinoma (OCCC) is a worst histological subtype than other ovarian malignant tumor. Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a promising target for ovarian cancer therapy. The aims of this study were to validate the efficacy of HB-EGF-targeted therapy for OCCC and to identify the transcription factor that contributed to the induction of HB-EGF by SN38 treatment in OCCC cells. HB-EGF was highly expressed in OCCC cells, and an increase of HB-EGF was induced by SN38 which had only antitumor effect among conventional anticancer agents on OCCC. A specific inhibitor of HB-EGF, a cross-reacting material 197 (CRM197), led to a synergistic increase in the number of apoptotic OCCC cells with the treatment of SN38. The luciferase assay with 5'-deletion promoter constructs identified a GC-rich element between -125 and -178 (the distal transcription start site was denoted +1) as a cis-regulatory region, and the treatment of SN38 induced luciferase activity in this region. An in silico and chromatin immunoprecipitation analysis estimated that SP1 bound to the cis-regulatory region of HB-EGF in OCCC cells. Real-time PCR and cell viability assays showed that the transfection of a small interfering RNA targeting SP1 suppressed the expression of HB-EGF induced by SN38, resulting in the enhanced sensitivity of SN38. Taken together, these results indicate that induction of HB-EGF expression contributed to defense mechanism against treatment of SN38 through the transcriptional activity of SP1 in OCCC cells.

Clinicopathological and prognostic significance of epidermal growth factor receptor overexpression in patients with esophageal adenocarcinoma: a meta-analysis

The prognostic significance of epidermal growth factor receptor (EGFR) overexpression in patients with esophageal adenocarcinoma (EAC) remains controversial. Eligible studies that investigated the association between survival in EAC and the expression status of EGFR were identified by an electronic search of PubMed, EMBASE, and ISI Web of Science. A meta-analysis was performed to clarify the impact of EGFR overexpression on clinicopathological parameters or overall survival (OS) in EAC. A total of seven studies including 1028 patients were subjected to the final analysis. The overall results suggested that overexpression of EGFR was significantly correlated with not only the depth of invasion, lymph node status, and tumors stage of EAC, with a pooled odds ratio of 2.99 (95% confidence interval [CI]: 1.07-8.35; Z = 2.09; P = 0.037), 3.05 (95% CI: 1.77-5.27; Z = 4.00; P < 0.001), and 5.37 (95% CI: 2.49-11.57; Z = 4.29; P < 0.001), respectively, but also the poorer OS with a pooled hazard ratio of 2.20 (95% CI: 1.47-3.31; Z = 3.79; P < 0.001). Overexpression of EGFR correlates with not only the clinicopathological features, but also the worse OS, and it might be useful as a predictive biomarker in clinical practice, yet the clinicopathological and prognostic role of EGFR in EAC still needs further confirmation by well-designed prospective studies.

Targeting the sheddase activity of ADAM17 by an anti-ADAM17 antibody D1(A12) inhibits head and neck squamous cell carcinoma cell proliferation and motility via blockage of bradykinin induced HERs transactivation

A disintegrin and metalloproteinase 17 (ADAM17) regulates key cellular processes including proliferation and migration through the shedding of a diverse array of substrates such as epidermal growth factor receptor (EGFR) ligands. ADAM17 is implicated in the pathogenesis of many diseases including rheumatoid arthritis and cancers such as head and neck squamous cell carcinoma (HNSCC). As a central mediator of cellular events, overexpressed EGFR is a validated molecular target in HNSCC. However, EGFR inhibition constantly leads to tumour resistance. One possible mechanism of resistance is the activation of alternative EGFR family receptors and downstream pathways via the release of their ligands. Here, we report that treating human HNSCC cells in vitro with a human anti-ADAM17 inhibitory antibody, D1(A12), suppresses proliferation and motility in the absence or presence of the EGFR tyrosine kinase inhibitor (TKI) gefitinib. Treatment with D1(A12) decreases both the endogenous and the bradykinin (BK)-stimulated shedding of HER ligands, accompanied by a reduction in the phosphorylation of HER receptors and downstream signalling pathways including STAT3, AKT and ERK. Knockdown of ADAM17, but not ADAM10, also suppresses HNSCC cell proliferation and migration. Furthermore, we show that heregulin (HRG) and heparin-binding epidermal growth factor like growth factor (HB-EGF) predominantly participate in proliferation and migration, respectively. Taken together, these results demonstrate that D1(A12)-mediated inhibition of cell proliferation, motility, phosphorylation of HER receptors and downstream signalling is achieved via reduced shedding of ADAM17 ligands. These findings underscore the importance of ADAM17 and suggest that D1(A12) might be an effective targeted agent for treating EGFR TKI-resistant HNSCC.

Treatment of capecitabine-induced hand-foot syndrome using a topical retinoid: A case report

Capecitabine is a chemotherapeutic drug used in patients with breast, colon and gastric cancer. Hand-foot syndrome (HFS) is a type of dermatitis that frequently occurs as a reaction to capecitabine. To date, no effective strategies have been found to prevent or reverse HFS. Furthermore, chemotherapy induces an elevation in the expression of heparin-binding epidermal growth factor-like growth factor (HB-EGF), and this activation represents a critical mechanism for the induction of chemotherapeutic resistance. Adapalene is a third-generation synthetic retinoid. Topical retinoids are important therapeutic anti-aging agents for managing photodamaged skin, and are known to increase HB-EGF levels, which is important for skin wound healing. Accordingly, the current report focused on the topical retinoids that increase HB-EGF expression in the skin, and we hypothesized that these topical retinoids induce local chemotherapeutic resistance in the skin of patients receiving chemotherapy and consequently, decrease the cutaneous side-effects of chemotherapy. This report presents a case of the successful treatment of refractory HFS induced by capecitabine using the topical application of adapalene. Topical adapalene was applied for 3 months and significantly reduced inflammation and pain following chemotherapy. Topical retinoids may have the potential to effectively treat capecitabine-induced HFS by increasing HB-EGF expression and decreasing cutaneous side-effects. Further studies are required to establish the therapeutic efficacy of topical retinoids on HFS.

Ableson kinases negatively regulate invadopodia function and invasion in head and neck squamous cell carcinoma by inhibiting an HB-EGF autocrine loop

Head and neck squamous cell carcinoma (HNSCC) has a proclivity for locoregional invasion. HNSCC mediates invasion in part through invadopodia-based proteolysis of the extracellular matrix (ECM). Activation of Src, Erk1/2, Abl and Arg downstream of epidermal growth factor receptor (EGFR) modulates invadopodia activity through phosphorylation of the actin regulatory protein cortactin. In MDA-MB-231 breast cancer cells, Abl and Arg function downstream of Src to phosphorylate cortactin, promoting invadopodia ECM degradation activity and thus assigning a pro-invasive role for Ableson kinases. We report that Abl kinases have an opposite, negative regulatory role in HNSCC where they suppress invadopodia and tumor invasion. Impairment of Abl expression or Abl kinase activity with imatinib mesylate enhanced HNSCC matrix degradation and 3D collagen invasion, functions that were impaired in MDA-MB-231. HNSCC lines with elevated EGFR and Src activation did not contain increased Abl or Arg kinase activity, suggesting that Src could bypass Abl/Arg to phosphorylate cortactin and promote invadopodia ECM degradation. Src-transformed Abl(-/-)/Arg(-/-) fibroblasts produced ECM degrading invadopodia containing pY421 cortactin, indicating that Abl/Arg are dispensable for invadopodia function in this system. Imatinib-treated HNSCC cells had increased EGFR, Erk1/2 and Src activation, enhancing cortactin pY421 and pS405/418 required for invadopodia function. Imatinib stimulated shedding of the EGFR ligand heparin-binding EGF-like growth factor (HB-EGF) from HNSCC cells, where soluble HB-EGF enhanced invadopodia ECM degradation in HNSCC but not in MDA-MB-231. HNSCC cells treated with inhibitors of the EGFR-invadopodia pathway indicated that EGFR and Src are required for invadopodia function. Collectively, our results indicate that Abl kinases negatively regulate HNSCC invasive processes through suppression of an HB-EGF autocrine loop responsible for activating a EGFR-Src-cortactin cascade, in contrast to the invasion promoting functions of Abl kinases in breast and other cancer types. Our results provide mechanistic support for recent failed HNSCC clinical trials utilizing imatinib.

Persistent activation of pancreatic stellate cells creates a microenvironment favorable for the malignant behavior of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most common malignant tumors with poor prognosis due to extremely high malignancy, low rate of eligibility for surgical resection and chemoradiation resistance. Increasing evidence indicate that the interaction between activated pancreatic stellate cells (PSCs) and PDAC cells plays an important role in the development of PDAC. By producing high levels of cytokines, chemotactic factors, growth factors and excessive extracellular matrix (ECM), PSCs create desmoplasia and a hypoxic microenvironment that promote the initiation, development, evasion of immune surveillance, invasion, metastasis and resistance to chemoradiation of PDAC. Therefore, targeting the interaction between PSCs and PDAC cells may represent a novel therapeutic approach to advanced PDAC, especially therapies that target PSCs of the pancreatic tumor microenvironment.

Molecular hierarchy of heparin-binding EGF-like growth factor-regulated angiogenesis in triple-negative breast cancer

Heparin-binding EGF-like growth factor (HB-EGF) is one of several proangiogenic factors and represents a possible therapeutic target for patients with triple-negative breast cancer (TNBC). However, the role of HB-EGF in promoting tumor aggressiveness in TNBC remains unclear. To investigate specific genes and pathways involved in TNBC tumorigenesis, we profiled gene expression changes in two TNBC cell lines under two-dimensional culture (2DC) and three-dimensional culture (3DC) and in a tumor xenograft model. We identified simultaneous upregulation of HB-EGF, VEGFA, and angiopoietin-like 4 (ANGPTL4) in 3DC and tumor xenografts, compared with 2DC. We show that HB-EGF regulates the expression of VEGFA or ANGPTL4 via transcriptional regulation of hypoxia-inducible factor-1α and NF-κB. Furthermore, suppression of VEGFA or ANGPTL4 expression enhanced HB-EGF expression, highlighting a unique regulatory loop underlying this angiogenesis network. Targeted knockdown of HB-EGF significantly suppressed tumor formation in a TNBC xenograft model, compared with individual knockdown of either VEGFA or ANGPTL4, by reducing the expression of both VEGFA and ANGPTL4. In patients with TNBC, VEGFA or ANGPTL4 expression was also significantly correlated with HB-EGF expression. Low concentrations of exogenously added HB-EGF strongly activated the proliferation of endothelial cells, tube formation, and vascular permeability in blood vessels, in a similar fashion to high doses of VEGFA and ANGPTL4. Taken together, these results suggest that HB-EGF plays a pivotal role in the acquisition of tumor aggressiveness in TNBC by orchestrating a molecular hierarchy regulating tumor angiogenesis.

Telmisartan inhibits cell proliferation by blocking nuclear translocation of ProHB-EGF C-terminal fragment in colon cancer cells

Background & Aims

Current treatment target toward advanced colorectal cancers is mainly focused on the epidermal growth factor receptor (EGFR) signaling, but its additive effects with chemotherapy are still limited. A disintegrin and metalloproteinase (ADAM) cleaves the proheparin-binding epidermal growth factor like growth factor (proHB-EGF). And soluble HB-EGF activates EGFR. In parallel, the carboxy-terminal fragment of proHB-EGF (HB-EGF-CTF) translocates into the inner nuclear membrane, and subsequently exerts on the regulation of cell proliferation by binding nuclear promyelocytic leukemia zinc finger (PLZF) protein, a transcriptional repressor, thereby causing its nuclear export. We hypothesized that the inhibition of HB-EGF-CTF nuclear translocation may be a new strategy in preventing cell proliferation.

Methods

12-O-tetradecanoylphorbor-13-acetate (TPA) was treated to activate ADAM. Nine-thousand chemical compounds were screened for their efficacies in blocking the binding of HB-EGF-CTF to promyelocytic leukemia zinc finger (PLZF) with Alphascreen system. The obtained candidates were then used to block the binding of HB-EGF-CTF to PLZF in colon cancer cells, HT29 and HCT116. Cell proliferation was investigated with a growth curve assay. The intracellular localization, and association between HB-EGF-CTF and PLZF, was assessed with immunofluorescent staining, and immunoprecipitation and Western blotting, respectively. The effects of obtained candidates on EGFR phosphorylation and on nuclear translocation of HB-EGF-CTF and export of PLZF during the angiotensin II type1 receptor (AT1R) knockdown were also investigated.

Results

Telmisartan and candesartan were found to be potential candidates. Telmisartan inhibited TPA-induced cell proliferation stronger than candesartan. Telmisartan, but not candesartan blocked the nuclear translocation of HB-EGF-CTF, and binding of HB-EGF-CTF to PLZF, during TPA stimulation. Both telmisartan and candesartan did not inhibit TPA-induced EGFR phosphorylation, and telmisartan, but not candesartan, inhibited TPA-induced nuclear translocation of HB-EGF-CTF after knockdown of AT1R.

Conclusions

The inhibition of HB-EGF-CTF nuclear translocation with telmisartan may be a novel strategy in preventing cell proliferation.

Identification of the cancer cell proliferation and survival functions of proHB-EGF by using an anti-HB-EGF antibody

PURPOSE

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a member of the epidermal growth factor family. The membrane-bound proHB-EGF is known to be a precursor of the soluble form of HB-EGF (sHB-EGF), which promotes cell proliferation and survival. While the functions of sHB-EGF have been extensively studied, it is not yet fully understood if proHB-EGF is also involved in cellular signaling events. In this study, we utilized the anti-HB-EGF monoclonal antibodies Y-142 and Y-073, which have differential specificities toward proHB-EGF, in order to elucidate proHB-EGF functions in cancer cells.

EXPERIMENTAL DESIGN

The biological activities of proHB-EGF were assessed in cell proliferation, caspase activation, and juxtacrine activity assays by using a 3D spheroid culture of NUGC-3 cells.

RESULTS

Y-142 and Y-073 exhibited similar binding and neutralizing activities for sHB-EGF. However, only Y-142 bound to proHB-EGF. We could detect the function of endogenously expressed proHB-EGF in a 3D spheroid culture. Blocking proHB-EGF with Y-142 reduced spheroid formation, suppressed cell proliferation, and increased caspase activation in the 3D spheroid culture of NUGC-3 cells.

CONCLUSIONS

Our results show that proHB-EGF acts as a cell proliferation and cell survival factor in cancer cells. The results suggest that proHB-EGF may play an important role in tumor progression.

Plk1 phosphorylation of orc2 and hbo1 contributes to gemcitabine resistance in pancreatic cancer

Although gemcitabine is the standard chemotherapeutic drug for treatment of pancreatic cancer, almost all patients eventually develop resistance to this agent. Previous studies identified Polo-like kinase 1 (Plk1) as the mediator of gemcitabine resistance, but the molecular mechanism remains unknown. In this study, we show that Plk1 phosphorylation of Orc2 and Hbo1 mediates the resistance to gemcitabine. We show that the level of Plk1 expression positively correlates with gemcitabine resistance, both in pancreatic cancer cells and xenograft tumors. Overexpression of Plk1 increases gemcitabine resistance, while inhibition of Plk1 sensitizes pancreatic cancer cells to gemcitabine treatment. To validate our findings, we show that inhibition of Plk1 sensitizes tumors to gemcitabine treatment in a mouse xenograft study. Mechanistically, we find that Plk1 phosphorylation of Orc2 maintains DNA replication on gemcitabine treatment. Furthermore, Plk1 phosphorylation of Hbo1 transcriptionally increases cFos expression and consequently elevates its target multidrug resistance 1 (MDR1), which was previously reported to confer chemotherapeutic drug resistance. Knockdown of cFos or MDR1 sensitizes gemcitabine-resistant cells to gemcitabine treatment. Finally, pancreatic cancer cells expressing Plk1-unphosphorylatable mutants of Orc2 or Hbo1 are more sensitive to gemcitabine than cells expressing wild-type Orc2 or Hbo1. In short, our study provides a mechanism for Plk1-mediated gemcitabine resistance, suggesting that Plk1 is a promising target for treatment of gemcitabine-resistant pancreatic cancer.

Nuclear translocation of the cytoplasmic domain of HB-EGF induces gastric cancer invasion

Background

Membrane-anchored heparin-binding epidermal growth factor-like growth factor (proHB-EGF) yields soluble HB-EGF, which is an epidermal growth factor receptor (EGFR) ligand, and a carboxy-terminal fragment of HB-EGF (HB-EGF-CTF) after ectodomain shedding. We previously reported that HB-EGF-CTF and unshed proHB-EGF which has the cytoplasmic domain of proHB-EGF (HB-EGF-C), translocate from the plasma membrane to the nucleus and regulate cell cycle after shedding stimuli. However, the significance of nuclear exported HB-EGF-C in human gastric cancer is unclear.

Methods

We investigated the relationship between intracellular localization of HB-EGF-C and clinical outcome in 96 gastric cancer patients treated with gastrectomy. Moreover, we established stable gastric cancer cell lines overexpressing wild-type HB-EGF (wt-HB-EGF) and mutated HB-EGF (HB-EGF-mC), which prevented HB-EGF-C nuclear translocation after shedding. Cell motility between these 2 gastric cancer cell lines was investigated using a transwell invasion assay and a wound healing assay.

Results

Of the 96 gastric cancer cases, HB-EGF-C immunoreactivity was detected in both the nucleus and cytoplasm in 19 cases (19.8 %) and in the cytoplasm only in 25 cases (26.0 %). The nuclear immunoreactivity of HB-EGF-C was significantly increased in stage pT3/4 tumors compared with pT1/2 tumors (T1/2 vs. T3/4: 11.1 % vs. 36.4 %, P < 0.01). The growth of wt-HB-EGF- and HB-EGF-mC-expressing cells significantly increased compared with control cells, but the growth of HB-EGF-mC-expressing cells was significantly decreased compared with wt-HB-EGF-expressing cells. Gastric cancer cell invasion obviously increased in wt-HB-EGF-expressing cells, but invasion in HB-EGF-mC-expressing cells showed a slight increase compared with control cells. Moreover, wt-HB-EGF overexpression increased the effectiveness of wound healing, but had no significant effect in HB-EGF-mC-expressing cells.

Conclusions

Both the function of HB-EGF as an EGFR ligand and a novel signal for HB-EGF-C nuclear translocation induce gastric cancer growth, whereas HB-EGF-C nuclear translocation independently plays a critical role in gastric cancer invasion. The present study demonstrated that HB-EGF-C nuclear translocation might be crucial in gastric cancer invasion. HB-EGF-C nuclear translocation may offer a prognostic marker and a new molecular target for gastric cancer therapy.

The anti-tumor effect of cross-reacting material 197, an inhibitor of heparin-binding EGF-like growth factor, in human resistant ovarian cancer

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a promising target for ovarian cancer therapy. Cross-reacting material 197 (CRM197), a specific HB-EGF inhibitor, has been proven to represent possible chemotherapeutic agent for ovarian cancer. However, the effect of CRM197 on the resistant ovarian carcinoma cells has not been sufficiently elucidated. Here, we found that HB-EGF was over-expressed in a paclitaxel-resistant human ovarian carcinoma cell line (A2780/Taxol) and a cisplatin-resistant cell line (A2780/CDDP), as well as the xenograft mouse tissue samples with these cells. To investigate the possible significance of the HB-EGF over-expression in A2780/Taxol and A2780/CDDP cells, we inhibited HB-EGF expression by CRM197 to investigate the effect of CRM197 treatment on these cells. We observed that CRM197 significantly induced anti-proliferative activity in a dose-dependent manner with the cell-cycle arrest at the G0/G1 phase and enhanced apoptosis in A2780/Taxol and A2780/CDDP cells. The sensitive ovarian carcinoma parental cell line (A2780), A2780/Taxol and A2780/CDDP cells formed tumors in nude mice, and enhanced tumorigenicity was observed in drug-resistant tumors. Furthermore, we observed that CRM197 significantly suppressed the growth of drug-resistant ovarian cancer xenografts in vivo (p<0.001). These results suggest that CRM197 as an HB-EGF-targeted agent has potent anti-tumor activity in paclitaxel- and cisplatin-resistant ovarian cancer which over-express HB-EGF.

Calpain 2-dependent IκBα degradation mediates CPT-11 secondary resistance in colorectal cancer xenografts

CPT-11 (irinotecan), the first-line chemotherapy for advanced stage colorectal cancer, remains inactive in about half of patients (primary chemoresistance) and almost all initial responders develop secondary resistance after several courses of treatment (8 months on average). Nude mice bearing HT-29 colon cancer xenografts were treated with CPT-11 and/or an NF-κB inhibitor for two courses. We confirm that NF-κB inhibition potentiated CPT-11 anti-tumoural effect after the first course of treatment. However, tumours grew again at the end of the second course of treatment, generating resistant tumours. We observed an increase in the basal NF-κB activation in resistant tumours and in two resistant sublines, either obtained from resistant HT-29 tumours (HT-29R cells) or generated in vitro (RSN cells). The decrease of NF-κB activation in HT-29R and RSN cells by stable transfections with the super-repressor form of IκBα augmented their sensitivity to CPT-11. Comparing gene expression profiles of HT-29 and HT-29R cells, we identified the S100A10/Annexin A2 complex and calpain 2 as over-expressed potential NF-κB inducers. SiRNA silencing of calpain 2 but not of S100A10 and/or annexin A2, resulted in a decrease in NF-κB activation, an increase in cellular levels of IκBα and a partial restoration of the CPT-11 sensitivity in both HT-29R and RSN cells, suggesting that calpain 2-dependent IκBα degradation mediates CPT-11 secondary resistance. Thus, targeted therapies directed against calpain 2 may represent a novel strategy to enhance the anti-cancer efficacy of CPT-11.

Non-invasive, quantitative monitoring of hyperthermia-induced EGFR activation in xenograft tumours

PURPOSE

To examine the molecular mechanism of cellular EGFR activation during hyperthermia treatment.

MATERIALS AND METHODS

EGR activities in tumour cells were quantified through the use of a recently developed split-luciferase-based EGFR reporter system which allowed us to monitor EGFR activation in vitro as well as in vivo in a non-invasive manner.

RESULTS

We found that hyperthermia treatment of MDA-MB231 breast cancer cells resulted in a strong induction of EGFR activity in tissue culture as well as in xenograft tumours. Furthermore, we found that this induction is mediated by the heat shock protein Hsp90. Administration of the specific Hsp90 inhibitor geldanamycin as well as RNAi directed against HSP90 effectively inhibited EGFR activation, suggesting an essential role for Hsp90 in hyperthermia-induced EGFR activation. In addition, cells treated with geldanamycin were sensitised to heat treatment, suggesting that adding Hsp90 inhibitors to hyperthermia regimens might have a beneficial effect for cancer treatment.

CONCLUSIONS

Our bioluminescent imaging reporter provided a powerful tool to examine hyperthermia-induced EGFR activation in vitro as well as in vivo. Hsp90 was found to be a key factor mediating heat-induced EGFR activation in tumour cells.

An EGFR inhibitor enhances the efficacy of SN38, an active metabolite of irinotecan, in SN38-refractory gastric carcinoma cells

BACKGROUND

Acquired drug resistance to irinotecan is one of the significant obstacles in the treatment of advanced gastric cancer. This study was performed to clarify the effect of epidermal growth factor receptor (EGFR) inhibitors in combination with SN38, an active metabolite of irinotecan, on the proliferation of irinotecan-refractory gastric cancer.

METHODS

Two irinotecan-resistant gastric cancer cell lines, OCUM-2M/SN38 and OCUM-8/SN38 were, respectively, established by stepwise exposure to SN38 from the parent gastric cancer cell lines OCUM-2M and OCUM-8. The combination effects of two EGFR inhibitors, gefitinib and lapatinib, with SN38 on proliferation, apoptosis, and cell cycle on gastric cancer cells were examined.

RESULTS

Gefitinib or lapatinib showed synergistic anti-tumour effects against OCUM-2M/SN38 and OCUM-8/SN38 cells when used in combination with SN38, but not against OCUM-2M or OCUM-8 cells. SN38 increased the expression of EGFR and HER2 in OCUM-2M/SN38 and OCUM-8/SN38 cells. The combination of an EGFR inhibitor and SN38 significantly increased the levels of apoptosis-related molecules, caspase-6, p53, and DAPK-2, and resulted in the induction of apoptosis of irinotecan-resistant cells. The EGFR inhibitors increased the S-phase and decreased the UGT1A1 and ABCG expression in irinotecan-resistant cells. The SN38 plus Lapatinib group more effectively suppressed in vivo tumour growth by OCUM-2M/SN38 cells than either alone group.

CONCLUSION

The combination treatment with an EGFR inhibitor and irinotecan might produce synergistic anti-tumour effects for irinotecan-refractory gastric cancer cells. The regulation of SN38 metabolism-related genes and cell cycle by EGFR inhibitors might be responsible for the synergism.

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.

Heparin-binding EGF-like factor augments esophageal epithelial cell proliferation, migration and inhibits TRAIL-mediated apoptosis via EGFR/MAPK signaling

OBJECTIVE

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) has been shown to stimulate the growth and migration of human keratinocytes in an autocrine or paracrine manner. Bearing in mind the preceding narratives, present study was designed to explore the role of HB-EGF on esophageal epithelial cell growth, migration and anti-apoptosis.

MATERIAL AND METHODS

HET-1A and TTn cells were treated with recombinant HB-EGF, and cell proliferation and migration were assessed by MTT and Boyden chamber assays, respectively. Anti-apoptotic effects of HB-EGF was studied by Bcl-2/Bcl-xL gene expression and utilizing a TNF-related death apoptosis inducing ligand (TRAIL).

RESULTS

Recombinant HB-EGF promotes human esophageal epithelial cell proliferation in a dose dependent manner, where 1 and 10 ng/ml doses were found to be most effective. HB-EGF induced cell migration was noted in TTn, but not in HET-1A cells. Recombinant HB-EGF induced the Bcl-2, Bcl-xL mRNA/protein expression in HET-1A and TTn cells. TRAIL induced the apoptosis in TTn, whereas it was significantly inhibited in HB-EGF treated conditions. Finally, we also revealed HB-EGF induced phosphorylation of EGFR and p38 MAPK in those cell lines, while all cellular functions were repressed by EGFR inhibitor AG1478.

CONCLUSION

HB-EGF promotes esophageal epithelial cell proliferation, migration and induces anti-apoptotic gene expression via EGFR/p38 MAPK phosphorylation.

Regulation of heparin-binding EGF-like growth factor by miR-212 and acquired cetuximab-resistance in head and neck squamous cell carcinoma

Background

We hypothesized that chronic inhibition of epidermal growth factor receptor (EGFR) by cetuximab, a monoclonal anti-EGFR antibody, induces up-regulation of its ligands resulting in resistance and that microRNAs (miRs) play an important role in the ligand regulation in head and neck squamous cell carcinoma (HNSCC).

Methodology/Principal Findings

Genome-wide changes in gene and miR expression were determined in cetuximab-sensitive cell line, SCC1, and its resistant derivative 1Cc8 using DNA microarrays and RT-PCR. The effects of differentially expressed EGFR ligands and miRs were examined by MTS, colony formation, ELISA, and western blot assays. Heparin-binding EGF-like growth factor (HB-EGF) and its regulator, miR-212, were differentially expressed with statistical significance when SCC1 and 1Cc8 were compared for gene and miR expression. Stimulation with HB-EGF induced cetuximab resistance in sensitive cell lines. Inhibition of HB-EGF and the addition of miR-212 mimic induced cetuximab sensitivity in resistant cell lines. MicroRNA-212 and HB-EGF expression were inversely correlated in an additional 33 HNSCC and keratinocyte cell lines. Six tumors and 46 plasma samples from HNSCC patients were examined for HB-EGF levels. HB-EGF plasma levels were lower in newly diagnosed HNSCC patients when compared to patients with recurrent disease.

Conclusions/Significance

Increased expression of HB-EGF due to down-regulation of miR-212 is a possible mechanism of cetuximab resistance. The combination of EGFR ligand inhibitors or miR modulators with cetuximab may improve the clinical outcome of cetuximab therapy in HNSCC.

Tailored cancer immunotherapy using combinations of chemotherapy and a mixture of antibodies against EGF-receptor ligands

Growth factors are implicated in several processes essential for cancer progression. Specifically, growth factors that bind to ErbB family receptors have been implicated in cell proliferation and in resistance of solid tumors to chemotherapy. We quantified ligand secretion by several human cancer cell lines, and generated mAbs against two ligands, namely TGF-alpha and heparin-binding EGF-like growth factor. These growth factors are frequently secreted by pancreatic tumor cell lines, including BxPC3 cells. The monoclonal antibodies were tested for their antigen specificity and ability to inhibit growth of BxPC3 cells in vitro. Combining the two antibodies resulted in enhanced inhibition of BxPC3 cell growth, both in vitro and in tumor-bearing animals. Hence, we combined the two antibodies with gemcitabine, an effective chemotherapeutic drug commonly used to treat pancreatic cancer patients. Because treatment with a combination of two monoclonal antibodies enhanced the ability of chemotherapy to inhibit BxPC3 tumors in mice, we propose a general cancer therapeutic strategy that entails profiling the repertoire of growth factors secreted by a tumor, and combining with chemotherapy several antibodies capable of blocking autocrine ligands.

Crosstalks between the receptors tyrosine kinase EGFR and TrkA and the GPCR, FPR, in human monocytes are essential for receptors-mediated cell activation

The G-protein coupled receptor (GPCR) fMLP receptor (FPR) and the two receptors tyrosine kinase (RTK), the nerve growth factor (NGF) receptor TrkA and the epidermal growth factor (EGF) receptor (EGFR) are involved in reactive oxygen species (ROS), matrix metalloproteinase-9 (MMP-9) production and CD11b membrane integrin upregulation. We show that in monocytes the three receptors crosstalk each other to modulate these pro-inflammatory mediators. Tyrphostin AG1478, the EGFR inhibitor, inhibits fMLP and NGF-associated ROS production, fMLP-associated CD11b upregulation and NGF-induced TrkA phosphorylation; K252a, the NGF receptor inhibitor, inhibits fMLP or EGF-associated ROS production, CD11b expression and EGF-induced EGFR phosphorylation; cyclosporine H, the FPR inhibitor inhibits EGF or NGF-associated ROS production, EGF-associated CD11b upregulation and prevents EGFR and TrkA phosphorylation by their respective ligand EGF and NGF. In response to fMLP, TrkA phosphorylation is inhibited by the EGFR inhibitor while EGFR phosphorylation is inhibited by the TrkA inhibitor. Receptor crosstalks are Src and ERK dependent. Down-regulation of each receptor by specific siRNA suppresses the ability of the two other receptors to promote ligand-mediated ERK phosphorylation and pro-inflammatory activities including ROS, MMP-9 production and CD11b upregulation. Thus, in monocytes GPCR ligands' activity involves activation of RTK while RTK-ligands activity engages GPCR-signalling molecules.

Activation of EGFR by proteasome inhibition requires HB-EGF in pancreatic cancer cells

Resistance to drug treatments underlies the high lethality of pancreatic ductal adenocarcinoma. Along with others, we have recently identified that proteasome inhibition is a promising therapeutic option in this highly refractory disease. The pleiotropic effects of proteasome inhibition include the activation of apoptotic signaling pathways and also antiapoptotic signaling pathways such as EGFR, AKT and the MAP kinases that reduce the apoptotic potential of this class of drug. In this study, we sought to determine the mechanism behind the activation of EGFR in response to proteasome inhibition in pancreatic cancer cells. We found that the second-generation proteasome inhibitor NPI-0052 induced the mRNA transcription of several EGFR family ligands (EGF, HB-EGF and epiregulin), however only increases in HB-EGF were detected at the protein level. Using both pharmacological inhibitors and lentiviral-mediated shRNA knockdown of EGFR ligand expression, we discovered that ligand cleavage by MMP/ADAMs and HB-EGF expression is required for activation of EGFR in response to proteasome inhibition. Furthermore, we discover that induction of HB-EGF is dependent on reactive oxygen species and p38-MAPK signaling but not ERK and that the transcription factor SP-1 is involved in NPI-0052-induced HB-EGF transcription. Together, these results indicate that stress signaling leading to induction of HB-EGF expression and increases in MMP/ADAM-dependent HB-EGF cleavage are responsible for proteasome inhibitor-induced activation of EGFR in pancreatic cancer cells.

Understanding the causes of multidrug resistance in cancer: a comparison of doxorubicin and sunitinib

Multiple molecular, cellular, micro-environmental and systemic causes of anticancer drug resistance have been identified during the last 25 years. At the same time, genome-wide analysis of human tumor tissues has made it possible in principle to assess the expression of critical genes or mutations that determine the response of an individual patient's tumor to drug treatment. Why then do we, with a few exceptions, such as mutation analysis of the EGFR to guide the use of EGFR inhibitors, have no predictive tests to assess a patient's drug sensitivity profile. The problem urges the more with the expanding choice of drugs, which may be beneficial for a fraction of patients only. In this review we discuss recent studies and insights on mechanisms of anticancer drug resistance and try to answer the question: do we understand why a patient responds or fails to respond to therapy? We focus on doxorubicin as example of a classical cytotoxic, DNA damaging agent and on sunitinib, as example of the new generation of (receptor) tyrosine kinase-targeted agents. For both drugs, classical tumor cell autonomous resistance mechanisms, such as drug efflux transporters and mutations in the tumor cell's survival signaling pathways, as well as micro-environment-related resistance mechanisms, such as changes in tumor stromal cell composition, matrix proteins, vascularity, oxygenation and energy metabolism may play a role. Novel agents that target specific mutations in the tumor cell's damage repair (e.g. PARP inhibitors) or that target tumor survival pathways, such as Akt inhibitors, glycolysis inhibitors or mTOR inhibitors, are of high interest. In order to increase the therapeutic index of treatments, fine-tuned synergistic combinations of new and/or classical cytotoxic agents will be designed. More quantitative assessment of potential resistance mechanisms in real tumors and in real time, such as by kinase profiling methodology, will be developed to allow more precise prediction of the optimal drug combination to treat each patient.

Targeting EGFR resistance networks in head and neck cancer

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

Gene expression analysis of an EGFR indirectly related pathway identified PTEN and MMP9 as reliable diagnostic markers for human glial tumor specimens

In this study the mRNA levels of five EGFR indirectly related genes, EGFR, HB-EGF, ADAM17, PTEN, and MMP9, have been assessed by Real-time PCR in a panel of 37 glioblastoma multiforme specimens and in 5 normal brain samples; as a result, in glioblastoma, ADAM17 and PTEN expression was significantly lower than in normal brain samples, and, in particular, a statistically significant inverse correlation was found between PTEN and MMP9 mRNA levels. To verify if this correlation was conserved in gliomas, PTEN and MMP9 expression was further investigated in an additional panel of 16 anaplastic astrocytoma specimens and, in parallel, in different human normal and astrocytic tumor cell lines. In anaplastic astrocytomas PTEN expression was significantly higher than in glioblastoma multiforme, but no significant correlation was found between PTEN and MMP9 expression. PTEN and MMP9 mRNA levels were also employed to identify subgroups of specimens within the different glioma malignancy grades and to define a gene expression-based diagnostic classification scheme. In conclusion, this gene expression survey highlighted that the combined measurement of PTEN and MMP9 transcripts might represent a novel reliable tool for the differential diagnosis of high-grade gliomas, and it also suggested a functional link involving these genes in glial tumors.

Down-regulation of cIAP2 enhances 5-FU sensitivity through the apoptotic pathway in human colon cancer cells

Currently 5-fluorouracil (5-FU) plays a central role in the chemotherapeutic regimens for colorectal cancers and thus it is important to understand the mechanisms that determine 5-FU sensitivity. The expression profiles of human colon cancer cell line DLD-1, its 5-FU-resistant subclone DLD-1/FU and a further 21 types of colon cancer cell lines were compared to identify the novel genes defining the sensitivity to 5-FU and to estimate which population of genes is responsible for 5-FU sensitivity. In the hierarchical clustering, DLD-1 and DLD-1/FU were most closely clustered despite over 100 times difference in their 50% inhibitory concentration of 5-FU. In DLD-1/FU, the population of genes differentially expressed compared to DLD-1 was limited to 3.3%, although it ranged from 4.8% to 24.0% in the other 21 cell lines, thus indicating that the difference of 5-FU sensitivity was defined by a limited number of genes. Next, the role of the cellular inhibitor of apoptosis 2 (cIAP2) gene, which was up-regulated in DLD-1/FU, was investigated for 5-FU resistance using RNA interference. The down-regulation of cIAP2 efficiently enhanced 5-FU sensitivity, the activation of caspase 3/7 and apoptosis under exposure to 5-FU. The immunohistochemistry of cIAP2 in cancer and corresponding normal tissues from colorectal cancer patients in stage III revealed that cIAP2 was more frequently expressed in cancer tissues than in normal tissues, and cIAP2-positive patients had a trend toward early recurrence after fluorouracil-based chemotherapy. Although the association between drug sensitivity and the IAP family in colorectal cancer has not yet been discussed, cIAP2 may therefore play an important role as a target therapy in colorectal cancer.

The expression of heparin-binding epidermal growth factor-like growth factor by regulatory macrophages

We previously described a population of regulatory macrophages that produced high levels of IL-10 and low levels of IL-12/23. We now describe and characterize the expression of heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) by these macrophages. HB-EGF has previously been associated with a number of physiological and pathological conditions, including tumor growth and angiogenesis. The induction of HB-EGF in regulatory macrophages is due to new transcription and not to increased mRNA stability. The transcription factor Sp1 is a major factor in HB-EGF production, and knockdown of Sp1 substantially diminishes HB-EGF production. Sp1 was recruited to three sites within the first 2 kb of the HB-EGF promoter following stimulation, and the site located at -83/-54 was required for HB-EGF promoter activity. These regions of the promoter become more accessible to endonuclease activity following macrophage activation, and this accessibility was contingent on activation of the MAPK, ERK. We show that several experimental manipulations that give rise to regulatory macrophages also result in HB-EGF production. These observations indicate that in addition to the secretion of the anti-inflammatory cytokine IL-10, another novel characteristic of regulatory macrophages is the production of angiogenic HB-EGF.

Mechanisms of tumor resistance to EGFR-targeted therapies

BACKGROUND

Much effort has been devoted to development of cancer therapies targeting EGFR, based on its role in regulating cell growth. Small-molecule and antibody EGFR inhibitors have clinical roles based on their efficacy in a subset of cancers, generally as components of combination therapies. Many cancers are either initially resistant to EGFR inhibitors or become resistant during treatment, limiting the efficacy of these reagents.

OBJECTIVE/METHODS

To review cellular resistance mechanisms to EGFR-targeted therapies.

RESULTS/CONCLUSIONS

The best validated of these mechanisms include activation of classic ATP-binding casette (ABC) multidrug transporters; activation or mutation of EGFR; and overexpression or activation of signaling proteins operating in relation to EGFR. We discuss current efforts and potential strategies to override these sources of resistance. We describe emerging systems-biology-based concepts of alternative resistance to EGFR-targeted therapies, and discuss their implications for use of EGFR-targeted and other targeted therapies.