ErbB Network Research Articles

Development of an adenosquamous carcinoma histopathology - selective lung metastasis model.

Preclinical tumor models with native tissue microenvironments provide essential tools to understand how heterogeneous tumor phenotypes relate to drug response. Here we present syngeneic graft models of aggressive, metastasis-prone histopathology-specific NSCLC tumor types driven by KRAS mutation and loss of LKB1 (KL): adenosquamous carcinoma (ASC) and adenocarcinoma (AC). We show that subcutaneous injection of primary KL; ASC cells results in squamous cell carcinoma (SCC) tumors with high levels of stromal infiltrates, lacking the source heterogeneous histotype. Despite forming subcutaneous tumors, intravenously injected KL;AC cells were unable to form lung tumors. In contrast, intravenous injection of KL;ASC cells leads to their lung re-colonization and lesions recapitulating the mixed AC and SCC histopathology, tumor immune suppressive microenvironment and oncogenic signaling profile of source tumors, demonstrating histopathology-selective phenotypic dominance over genetic drivers. Pan-ERBB inhibition increased survival, while selective ERBB1/EGFR inhibition did not, suggesting a role of the ERBB network crosstalk in resistance to ERBB1/EGFR. This immunocompetent NSCLC lung colonization model hence phenocopies key properties of the metastasis-prone ASC histopathology, and serves as a preclinical model to dissect therapy responses and metastasis-associated processes.

A Computational Framework for Prediction and Analysis of Cancer Signaling Dynamics from RNA Sequencing Data-Application to the ErbB Receptor Signaling Pathway.

Simple SummaryTemporal signaling dynamics are important for controlling the fate decisions of mammalian cells. In this study, we developed BioMASS, a computational platform for prediction and analysis of signaling dynamics using RNA-sequencing gene expression data. We first constructed a detailed mechanistic model of early transcriptional regulation mediated by ErbB receptor signaling pathway. After training the model parameters against phosphoprotein time-course datasets obtained from breast cancer cell lines, the model successfully predicted signaling activities of another untrained cell line. The result indicates that the parameters of molecular interactions in these different cell types are not particularly unique to the cell type, and the expression levels of the components of the signaling network are sufficient to explain the complex dynamics of the networks. Our method can be further expanded to predict signaling activity from clinical gene expression data for in silico drug screening for personalized medicine.A current challenge in systems biology is to predict dynamic properties of cell behaviors from public information such as gene expression data. The temporal dynamics of signaling molecules is critical for mammalian cell commitment. We hypothesized that gene expression levels are tightly linked with and quantitatively control the dynamics of signaling networks regardless of the cell type. Based on this idea, we developed a computational method to predict the signaling dynamics from RNA sequencing (RNA-seq) gene expression data. We first constructed an ordinary differential equation model of ErbB receptor → c-Fos induction using a newly developed modeling platform BioMASS. The model was trained with kinetic parameters against multiple breast cancer cell lines using autologous RNA-seq data obtained from the Cancer Cell Line Encyclopedia (CCLE) as the initial values of the model components. After parameter optimization, the model proceeded to prediction in another untrained breast cancer cell line. As a result, the model learned the parameters from other cells and was able to accurately predict the dynamics of the untrained cells using only the gene expression data. Our study suggests that gene expression levels of components within the ErbB network, rather than rate constants, can explain the cell-specific signaling dynamics, therefore playing an important role in regulating cell fate.

Temporal Dynamics of the Neuregulin-ErbB Network in the Murine Prefrontal Cortex across the Lifespan.

Neuregulin-ErbB signaling is essential for numerous functions in the developing, adult, and aging brain, particularly in the prefrontal cortex (PFC). Mouse models with disrupted Nrg and/or ErbB genes are relevant to psychiatric, developmental, and age-related disorders, displaying a range of abnormalities stemming from cortical circuitry impairment. Many of these models display nonoverlapping phenotypes dependent upon the gene target and timing of perturbation, suggesting that cortical expression of the Nrg-ErbB network undergoes temporal regulation across the lifespan. Here, we report a comprehensive temporal expression mapping study of the Nrg-ErbB signaling network in the mouse PFC across postnatal development through aging. We find that Nrg and ErbB genes display distinct expression profiles; moreover, splice isoforms of these genes are differentially expressed across the murine lifespan. We additionally find a developmental switch in ErbB4 splice isoform expression potentially mediated through coregulation of the lncRNA Miat expression. Our results are the first to comprehensively and quantitatively map the expression patterns of the Nrg-ErbB network in the mouse PFC across the postnatal lifespan and may help disentangle the pathway's involvement in normal cortical sequences of events across the lifespan, as well as shedding light on the pathophysiological mechanisms of abnormal Nrg-ErbB signaling in neurological disease.

Receptor Tyrosine Kinase Signaling Networks Define Sensitivity to ERBB Inhibition and Stratify Kras-Mutant Lung Cancers.

Most non-small cell lung cancers (NSCLC) contain nontargetable mutations, including KRAS, TP53, or STK11/LKB1 alterations. By coupling ex vivo drug sensitivity profiling with in vivo drug response studies, we aimed to identify drug vulnerabilities for these NSCLC subtypes. Primary adenosquamous carcinoma (ASC) or adenocarcinoma (AC) cultures were established from KrasG12D/+;Lkb1fl/fl (KL) tumors or AC cultures from KrasG12D/+;p53fl/fl (KP) tumors. Although p53-null cells readily propagated as conventional cultures, Lkb1-null cells required conditional reprograming for establishment. Drug response profiling revealed short-term response to MEK inhibition, yet long-term clonogenic assays demonstrated resistance, associated with sustained or adaptive activation of receptor tyrosine kinases (RTK): activation of ERBBs in KL cultures, or FGFR in AC cultures. Furthermore, pan-ERBB inhibition reduced the clonogenicity of KL cultures, which was exacerbated by combinatorial MEK inhibition, whereas combinatorial MEK and FGFR inhibition suppressed clonogenicity of AC cultures. Importantly, in vivo studies confirmed KL-selective sensitivity to pan-ERBB inhibition, which correlated with high ERBB ligand expression and activation of ERBB receptors, implying that ERBB network activity may serve as a predictive biomarker of drug response. Interestingly, in human NSCLCs, phosphorylation of EGFR or ERBB3 was frequently detected in ASCs and squamous cell carcinomas. We conclude that analysis of in situ ERBB signaling networks in conjunction with ex vivo drug response profiling and biochemical dissection of adaptive RTK activities may serve as a valid diagnostic approach to identify tumors sensitive to ERBB network inhibition.

PO-184 Proteomic profiling to predict response towards therapeutic monoclonal antibodies in HER2 low breast cancer

IntroductionERBB family of receptors tirosine kinases (RTK) are potent drivers of tumorogenesis and metastasis. In breast tumours, 70%–80% of patients, although clinically not classified as HER2 positive, show low or moderate expression of HER2 along with EGFR and ERBB3. Concomitant blockade with specific monoclonal antibodies based on proteomic profile determined by Reverse Phase Protein Array (RPPA), appears as a beneficial approach to improve treatment strategies.Material and methodsCancer cells lines from different breast cancer subtypes were selected based on their ERBB expression levels. Cell number was quantified upon exposure to different ligands (HRG1β, EGF, AREG, TGF) and to combinations of monoclonal antibodies targeting EGFR, ERBB2 and ERBB3 (cetuximab, trastuzumab/pertuzumab and lumretuzumab respectively). Using RPPA and over 100 specific antibodies, abundance and phosphorylation states of downstream signalling molecules in an extended MAPK/AKT network were quantified.Results and discussionsShort time stimulation with ERBB ligands, allowed to determine phosphorylation state of the ERBB receptors and their immediate downstream signalling effectors in different cell lines, and thus, to elucidate which combination therapy would be more effective in reverting such activation. For luminal A cell lines T47D and MCF7, stimulation with HRG1β led to a high phosphorylation levels of ERBB3 in both cell lines, but not for ERBB2, with higher phosphorylation in the T47D cell line. Proteomic activation profiles correlated with efficacy of inhibition after combination treatment with pertuzumab/lumretuzumab. For the triple negative cell lines MDA-MB468 and MDA-MB231, response to ligands stimulation did not identify a common activation pattern and thus only blockade of EGFR receptor showed minimal effects in MDA-MB468. Phosphorylation status of downstream signalling effectors in the AKT/MAPK network may help to identify putative targets responsible for incomplete unresponsiveness to ERBB blockade.ConclusionTargeting ERBB members in a HER2 moderate/low scenario seems to be a promising approach when combining targeted therapies. Phenotypic characterisation together with mathematical modelling based on the proteomic activation profile, aroused as a way to better predict response to drug combinations. Better characterisation of ERBB network activation profile in different tumour cell lines and in further tumour tissues, should help to pave the way to improve personalization treatment in HER2 low breast cancers.

The ERBB network facilitates KRAS-driven lung tumorigenesis.

KRAS is the most frequently mutated driver oncogene in human adenocarcinoma of the lung. There are presently no clinically proven strategies for treatment of KRAS-driven lung cancer. Activating mutations in KRAS are thought to confer independence from upstream signaling; however, recent data suggest that this independence may not be absolute. We show that initiation and progression of KRAS-driven lung tumors require input from ERBB family receptor tyrosine kinases (RTKs): Multiple ERBB RTKs are expressed and active from the earliest stages of KRAS-driven lung tumor development, and treatment with a multi-ERBB inhibitor suppresses formation of KRASG12D-driven lung tumors. We present evidence that ERBB activity amplifies signaling through the core RAS pathway, supporting proliferation of KRAS-mutant tumor cells in culture and progression to invasive disease in vivo. Brief pharmacological inhibition of the ERBB network enhances the therapeutic benefit of MEK (mitogen-activated protein kinase kinase) inhibition in an autochthonous tumor setting. Our data suggest that lung cancer patients with KRAS-driven disease may benefit from inclusion of multi-ERBB inhibitors in rationally designed treatment strategies.

Molecular Network Pathway Of ERBB In Diffuse-Type Gastric Cancer, Mesenchymal Stem Cells And Epithelial-Mesenchymal Transition

Epithelial-mesenchymal transition (EMT) is related to malignancy and metastasis in cancer. The molecular networks including tyrosine kinases are altered in gastric cancer (GC). This study aims to reveal the role of ERBBs (erb-b2 receptor tyrosine kinases) in EMT, and generate the molecular network pathway of ERBBs in diffusetype GC and mesenchymal stem cells (MSCs). The expression of ERBB genes was analyzed in MSCs and diffuse-type GC which has mesenchymal characteristics compared to intestinal-type GC. The signaling and molecular network of ERBB was analyzed using several databases, including cBioPortal for Cancer Genomics, Kyoto Encyclopedia of Genes and Genomes (KEGG), BioGRID and VaProS. ERBB2 and ERBB3 gene expression were up-regulated in diffuse-type GC compared to MSCs. The ERBB3 molecular network includes epidermal growth factor receptor (EGFR), cadherin 1 (CDH1), catenin beta 1 (CTNNB1) and EPH receptor A5 (EPHA5). These results demonstrate the importance of the ERBB network in cancer signaling, and revealed a ERBB3 network pathway model in diffuse-type GC and MSCs, and EMT.

NRG1-ErbB Lost in Translation: A New Paradigm for Lung Cancer?

Molecular lesions of the NRG1 gene were recently described as a new molecular feature of Invasive Mucinous Adenocarcinoma of the lung. The NRG1 chimeric ligand leads to aberrant activation of the ErbB2/ErbB3 signaling via PI3K-AKT and MAPK cellular cascades. This review aims to highlight the current knowledge about the ErbB network and the effect of NRG1 deregulation in lung cancer and their merger into the ErbB/PI3K-AKT axis modulation by current pharmacologic strategies. We performed a structured search of bibliographic databases for peer-reviewed literature to outline the state of the art with regard ErbB signaling deregulation and NRG1 function in lung cancer. The quality of retrieved papers was assessed using standard tools and one hundred thirty-five were included in the review. In many papers the molecular lesions affecting the ErbB receptors in lung cancer but also in other type of solid tumors were updated. Papers describing the physiological role of NRG1 in cells was also screened for the review preparation, as well as the paper reporting NRG1 fusions in lung cancer and their implication in aberrant ErbB pathway activation. Overall, this review highpoints how the knowledge of new molecular mechanisms of ErbB pathway deregulation may help in gaining new insights into the molecular status of lung cancer patients and unveil a novel molecular markers of patients' stratification. Moreover, this ultimately led the selection of new compounds designed to inhibit the bound between Nrg1-ErbB3 as a good alternative way to block the ErbB intracellular signaling.

SUMOylation regulates nuclear accumulation and signaling activity of the soluble intracellular domain of the ErbB4 receptor tyrosine kinase

Erb-B2 receptor tyrosine kinase 4 (ErbB4) is a kinase that can signal via a proteolytically released intracellular domain (ICD) in addition to classical receptor tyrosine kinase-activated signaling cascades. Previously, we have demonstrated that ErbB4 ICD is posttranslationally modified by the small ubiquitin-like modifier (SUMO) and functionally interacts with the PIAS3 SUMO E3 ligase. However, direct evidence of SUMO modification in ErbB4 signaling has remained elusive. Here, we report that the conserved lysine residue 714 in the ErbB4 ICD undergoes SUMO modification, which was reversed by sentrin-specific proteases (SENPs) 1, 2, and 5. Although ErbB4 kinase activity was not necessary for the SUMOylation, the SUMOylated ErbB4 ICD was tyrosine phosphorylated to a higher extent than unmodified ErbB4 ICD. Mutation of the SUMOylation site compromised neither ErbB4-induced phosphorylation of the canonical signaling pathway effectors Erk1/2, Akt, or STAT5 nor ErbB4 stability. In contrast, SUMOylation was required for nuclear accumulation of the ErbB4 ICD. We also found that Lys-714 was located within a leucine-rich stretch, which resembles a nuclear export signal, and could be inactivated by site-directed mutagenesis. Furthermore, SUMOylation modulated the interaction of ErbB4 with chromosomal region maintenance 1 (CRM1), the major nuclear export receptor for proteins. Finally, the SUMO acceptor lysine was functionally required for ErbB4 ICD-mediated inhibition of mammary epithelial cell differentiation in a three-dimensional cell culture model. Our findings indicate that a SUMOylation-mediated mechanism regulates nuclear localization and function of the ICD of ErbB4 receptor tyrosine kinase.

ErbB signaling antagonist ameliorates behavioral deficit induced by phencyclidine (PCP) in mice, without affecting metabolic syndrome markers

Schizophrenia is a severe syndrome that affects about 1% of the world population. Since the mid-1950s, antipsychotics have been used to treat schizophrenia with preference for treating positive symptoms; however, their tolerance level is low, there are numerous side effects, and only some patients respond to the treatment. Antipsychotic medications that are more effective, better tolerated, and with fewer adverse effects are urgently needed. Given the accumulating evidence of the role filled by the ErbB signaling network in the biology of the dopamine, GABA, and glutamate systems, and in the etiology of schizophrenia, we hypothesized that the ErbB network is a candidate for development of a novel agent through which various symptoms of schizophrenia and other psychiatric disorders might be treated.Herein, we studied, in mice, the capability of blocking the ErbB signaling, in comparison with the atypical antipsychotic drug clozapine, to counter schizophrenia-like behavior induced by acute and sub-chronic phencyclidine (PCP), and determined whether inhibition of the ErbB networks induced weight gain and affected social and exploratory behavior, and metabolic syndrome markers. We demonstrated that administration of the pan-ErbB inhibitor JNJ28871063 (JNJ) reduced the level of activity in the open field induced by an acute injection of PCP. Moreover, the ability of JNJ to attenuate the effect of PCP is as effective as clozapine. In addition and like clozapine, JNJ normalized social behavior impairment induced by sub-chronic PCP and stress. Adult JNJ-treated mice displayed normal sociability and exploratory behavior, and their serum cholesterol, LDL, and HDL levels were lower than in the saline-treated mice. Sub-chronic treatment did not affect weight gain, glucose levels, and the activity of hepatic enzymes catalase and SOD.These data suggest that treatment with JNJ attenuates abnormal behaviors induced by PCP, and has similar effects as the antipsychotic drug clozapine, with no adverse effects. Thus, the ErbB signaling can serve as a new starting point for non-dopaminergic-based drug development of schizophrenia.

Abstract 3329: Combinatorial blockade of ERBB receptors in HER2 low breast cancer

Abstract Large number of breast cancer patients clinically classified as HER2 negative, show low/moderate levels of HER2 along with other ERBB receptors. Concomitant blockade of EGFR, ERBB2 and ERBB3 with specific therapeutic antibodies (cetuximab, trastuzumab/pertuzumab and lumretuzumab, respectively) appears as a beneficial approach to improve survival of patients who have failed to previous treatment strategies. Additionally, ERBB3 expression has been reported as a trastuzumab resistance mechanism in HER2 positive subtypes.We have confirmed a specific pattern of ERBB receptors expression in different breast cancer subtypes. Individual and combined blockade of the receptors with therapeutic antibodies has been tested in vitro using a metabolic viability assay (Cell Titer Glo) and their effects in cell cycle status measured by BrdU staining. All four therapeutic antibodies bind to the respective extracellular domains inhibiting downstream signaling pathways. Response to individual treatment is cell dependent and correlates with EGFR expression in the triple negative MDA-MB-468 but not in luminal T47D cancer cell line. Response of T47D cells to lumretuzumab is higher when combined with pertuzumab or trastuzumab, suggesting ERBB2/ERBB3 dimer as the most relevant one, an effect more evident upon ectopic addition of NRG1 (only ligand for ERBB3). Long exposure of MDA-MB468 cells to cetuximab induces ERBB3 expression and increases its sensitivity to cetuximab when combined. As well as, in the HER2+ BT474 cancer cell line resistant to trastuzumab, higher levels of ERBB3 also make cells more sensitive to alternative anti-ERBB therapies. To establish the role of ERBB4 (no specific therapeutic antibody) in the whole ERBB network, stable knock-down regulation (shRNA) has been performed in T47D cells. Although treatment of HER2 overexpressing breast tumors has been successful, targeting other ERBB members in a HER2 moderate/low scenario seems to be a promising approach in combinatorial therapies; even in resistant cell lines. Thus, better characterization of ERBB network should help to pave the way for a personalized treatment of HER2 low breast cancer. [U.K.: Deceased March, 2016] Citation Format: Mireia Berdiel-Acer, Eileen Reinz, Khalid Abnaof, Sara Burmester, Rainer Will, Ulrike Korf, Stefan Wiemann. Combinatorial blockade of ERBB receptors in HER2 low breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3329. doi:10.1158/1538-7445.AM2017-3329

Abstract P6-15-02: Phenotypically distinct HRG positive cancer cells impact standard of care therapies in metastatic breast cancer models

Abstract ErbB3 is a member of the human epidermal growth factor receptor (ErbB or HER) family which is comprised of four receptors (ErbB1-4). A defining feature of the ErbB network is that two members of the family, ErbB2 and ErbB3, are non-autonomous. ErbB2 lacks the capacity to interact with a growth-factor ligand, whereas the kinase activity of ErbB3 is defective. Heregulin (HRG), the ErbB3 ligand, has been identified as a potent driver of proliferation and enhanced survival. HRG expression leads to a distinct tumor cell phenotype characterized by an inability to respond to the effects of numerous Standard of Care (SOC) therapies, including chemotherapies, anti-hormonal agents and other targeted therapeutics. In surveys of HRG expression, we have shown the presence of HRG+ cells in approximately 50% of the cases of most solid tumor types. We hypothesize that these HRG+ cells are protected from the effects of SOC therapy and continue to proliferate even in the presence of SOC, resulting in limited clinical benefit. In this model, if HRG activity is blocked, HRG+ cells become susceptible to SOC, resulting in enhanced clinical benefit. Seribantumab is a fully human anti-ErbB3 monoclonal antibody designed to block HRG activity by inhibiting the binding of HRG to ErbB3. In the presence of seribantumab, HRG+ tumor cells are predicted to be able to respond to co-administered SOC therapy. For hormone receptor positive (HR+) breast cancer, hormone deprivation strategies have proven clinical benefit in the adjuvant and metastatic settings. Unfortunately, clinical benefit from these therapies can be short-lived in some patients. Optimal clinical management of these patients requires a comprehensive molecular understanding of the drivers of rapid clinical progression. We and others have found that HRG mRNA expression measured in tumor samples defines a subgroup of patients who derive only limited clinical benefit from SOC when compared to patients whose tumors do not express HRG. This was observed in a previously published Phase 2 clinical study with exemestane, and preclinically with multiple classes of anti-hormonal agents, including letrozole and fulvestrant -- treatments that currently represent the mainstay of treatment options for HR+, HER2 negative (HER2-) advanced breast cancer. Here we will present data supporting the hypothesis that phenotypically distinct HRG+ cells in breast cancer models persist despite treatment with SOC and various novel classes of therapy. We will also show that the addition of the anti-ErbB3 antibody seribantumab to these other therapies promotes sustained treatment responses. Continued expansion of HRG+ cells could be the key to rapid clinical progression in breast cancer patients treated with SOC therapy. These findings support the development of seribantumab in combination with anti-hormonal agents in a planned Phase 3 clinical trial in HR+, HER2- advanced breast cancer. Citation Format: Finn GJ, Zhang H, Blois A, Mathews SE, Kudla AJ, Baum JS, Demars NA, Cieslewicz MJ, Czibere A. Phenotypically distinct HRG positive cancer cells impact standard of care therapies in metastatic breast cancer models [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-15-02.

Erlotinib-Induced Skin Inflammation Is IL-1 Mediated in KC-Tie2 Mice and Human Skin Organ Culture

Epidermal growth factor receptor (EGFR) is the prototypical member of the ErbB network comprised of four transmembrane receptor tyrosine kinases (EGFR/ErbB1, ErbB2, ErbB3, and ErbB4). These receptors bind EGF and heregulin family ligands in a dynamic, feedback-regulated fashion, activating multiple signal transduction pathways and ultimately affecting many cellular functions (Avraham and Yarden, 2011; Wilson et al., 2009). ErbB receptors and their ligands are overexpressed in a wide spectrum of hyperplastic epithelial disorders including psoriasis and cancers. Numerous monoclonal antibodies and receptor tyrosine kinase inhibitors have been designed to block their activation (Yarden and Pines, 2012), and are highly effective for treating colorectal and non-small cell lung cancers. However, skin toxicity is frequently observed in patients undergoing therapy with EGFR inhibitors (EGFRIs) (Lacouture, 2006), including papular and pustular eruptions of the face and trunk, nail changes, dry skin, itch, and hair loss (Lacouture and Lai, 2006). These side-effects are the major dose-limiting toxicity of EGFRI therapy (Boone et al., 2007) and emphasize the importance of understanding the mechanisms involved.

Clinical Evaluation of ErbB-Targeted CAR T-Cells, Following Intracavity Delivery in Patients with ErbB-Expressing Solid Tumors.

Adoptive cell therapy using gene-modified T-cells has achieved impressive results in the treatment of B-cell malignancies. However, the development of similar strategies to treat solid tumors raises challenges with respect to tumor antigen selection and the achievement of efficient T-cell homing, survival and sustained effector function within the tumor microenvironment. To address these challenges, we have developed a gene-modified cellular therapy called T4 immunotherapy. To generate T4 immunotherapy, autologous T-cells are engineered by retroviral transduction to co-express two transgenes: (1) a chimeric antigen receptor (CAR), T1E28z, targeted against a range of ErbB homodimers and heterodimers and (2) a chimeric cytokine receptor, 4αβ, that allows the selective ex vivo expansion of engineered cells using interleukin-4. Targeting of the extended ErbB network using CAR T-cells is supported by prevalence of ErbB dysregulation in diverse solid tumors and the clinical impact of monoclonal antibody therapy directed against members of this family. However, the key obstacle to effective clinical translation is risk of on-target toxicity owing to the lower level expression of ErbB family members in many healthy tissues. To de-risk T4 immunotherapy in man, we are undertaking a trial in patients with locally advanced or recurrent head and neck squamous cell carcinoma. In that setting, engineered T-cells are injected directly into the tumor without prior lymphodepletion, an approach that we believe will minimize risk of toxicity. This chapter outlines how we plan to advance the development of T4 immunotherapy thereafter in Phase II clinical testing. In that setting, regional (intracavitary) approaches will be used to administer this therapy to patients with epithelial ovarian cancer and malignant pleural mesothelioma.

Boolean ErbB network reconstructions and perturbation simulations reveal individual drug response in different breast cancer cell lines.

BackgroundDespite promising progress in targeted breast cancer therapy, drug resistance remains challenging. The monoclonal antibody drugs trastuzumab and pertuzumab as well as the small molecule inhibitor erlotinib were designed to prevent ErbB-2 and ErbB-1 receptor induced deregulated protein signalling, contributing to tumour progression. The oncogenic potential of ErbB receptors unfolds in case of overexpression or mutations. Dimerisation with other receptors allows to bypass pathway blockades. Our intention is to reconstruct the ErbB network to reveal resistance mechanisms. We used longitudinal proteomic data of ErbB receptors and downstream targets in the ErbB-2 amplified breast cancer cell lines BT474, SKBR3 and HCC1954 treated with erlotinib, trastuzumab or pertuzumab, alone or combined, up to 60 minutes and 30 hours, respectively. In a Boolean modelling approach, signalling networks were reconstructed based on these data in a cell line and time course specific manner, including prior literature knowledge. Finally, we simulated network response to inhibitor combinations to detect signalling nodes reflecting growth inhibition.ResultsThe networks pointed to cell line specific activation patterns of the MAPK and PI3K pathway. In BT474, the PI3K signal route was favoured, while in SKBR3, novel edges highlighted MAPK signalling. In HCC1954, the inferred edges stimulated both pathways. For example, we uncovered feedback loops amplifying PI3K signalling, in line with the known trastuzumab resistance of this cell line. In the perturbation simulations on the short-term networks, we analysed ERK1/2, AKT and p70S6K. The results indicated a pathway specific drug response, driven by the type of growth factor stimulus. HCC1954 revealed an edgetic type of PIK3CA-mutation, contributing to trastuzumab inefficacy. Drug impact on the AKT and ERK1/2 signalling axes is mirrored by effects on RB and RPS6, relating to phenotypic events like cell growth or proliferation. Therefore, we additionally analysed RB and RPS6 in the long-term networks.ConclusionsWe derived protein interaction models for three breast cancer cell lines. Changes compared to the common reference network hint towards individual characteristics and potential drug resistance mechanisms. Simulation of perturbations were consistent with the experimental data, confirming our combined reverse and forward engineering approach as valuable for drug discovery and personalised medicine.

A comprehensive review of the preclinical efficacy profile of the ErbB family blocker afatinib in cancer.

Afatinib (also known as BIBW 2992) has recently been approved in several countries for the treatment of a distinct type of epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer. This manuscript comprehensively reviews the preclinical data on afatinib, an irreversible inhibitor of the tyrosine kinase activity of members of the epidermal growth factor receptor family (ErbB) including EGFR, HER2 and ErbB4. Afatinib covalently binds to cysteine 797 of the EGFR and the corresponding cysteines 805 and 803 in HER2 and ErbB4, respectively. Such covalent binding irreversibly inhibits the tyrosine kinase activity of these receptors, resulting in reduced auto- and transphosphorylation within the ErbB dimers and inhibition of important steps in the signal transduction of all ErbB receptor family members. Afatinib inhibits cellular growth and induces apoptosis in a wide range of cells representative for non-small cell lung cancer, breast cancer, pancreatic cancer, colorectal cancer, head and neck squamous cell cancer and several other cancer types exhibiting abnormalities of the ErbB network. This translates into tumour shrinkage in a variety of in vivo rodent models of such cancers. Afatinib retains inhibitory effects on signal transduction and in vitro and in vivo cancer cell growth in tumours resistant to reversible EGFR inhibitors, such as those exhibiting the T790M mutations. Several combination treatments have been explored to prevent and/or overcome development of resistance to afatinib, the most promising being those with EGFR- or HER2-targeted antibodies, other tyrosine kinase inhibitors or inhibitors of downstream signalling molecules.

Quantification of ErbB Network Proteins in Three Cell Types Using Complementary Approaches Identifies Cell-General and Cell-Type-Specific Signaling Proteins

Relating protein concentration to cell-type-specific responses is one of the remaining challenges for obtaining a quantitative systems level understanding of mammalian signaling. Here we used mass-spectrometry (MS)- and antibody-based quantitative proteomic approaches to measure protein abundances for 75% of a hand-curated reconstructed ErbB network of 198 proteins, in two established cell types (HEK293 and MCF-7) and in primary keratinocyte cells. Comparison with other quantitative studies allowed building a set of ErbB network proteins expressed in all cells and another which are cell-specific and could impart specific properties to the network. As a proof-of-concept of the importance of protein concentration, we generated a small simplified mathematical model encompassing ligand binding, followed by receptor dimerization, activation, and degradation. The model predicts ErbB phosphorylation in HEK293, MCF-7, and keratinocyte cells simply by incorporating cell-type-specific ErbB1, ErbB2, and caveolin-1 abundances but otherwise contains similar rate constants. Altogether, the data provide a resource for protein abundances and localization to be included in larger mathematical models, enabling the generation of cell-type-specific computational models. MS data have been deposited to the ProteomeXchange via PRIDE (with identifier PXD000623) and PASSEL (with identifier PASS00372).

Preclinical in vivo modeling of cytokine release syndrome induced by ErbB-retargeted human T cells: identifying a window of therapeutic opportunity?

The ErbB network is dysregulated in many solid tumors. To exploit this, we have developed a chimeric Ag receptor (CAR) named T1E28z that targets several pathogenetically relevant ErbB dimers. T1E28z is coexpressed with a chimeric cytokine receptor named 4αβ (combination termed T4), enabling the selective expansion of engineered T cells using IL-4. Human T4(+) T cells exhibit antitumor activity against several ErbB(+) cancer types. However, ErbB receptors are also expressed in several healthy tissues, raising concerns about toxic potential. In this study, we have evaluated safety of T4 immunotherapy in vivo using a SCID beige mouse model. We show that the human T1E28z CAR efficiently recognizes mouse ErbB(+) cells, rendering this species suitable to evaluate preclinical toxicity. Administration of T4(+) T cells using the i.v. or intratumoral routes achieves partial tumor regression without clinical or histopathologic toxicity. In contrast, when delivered i.p., tumor reduction is accompanied by dose-dependent side effects. Toxicity mediated by T4(+) T cells results from target recognition in both tumor and healthy tissues, leading to release of both human (IL-2/IFN-γ) and murine (IL-6) cytokines. In extreme cases, outcome is lethal. Both toxicity and IL-6 release can be ameliorated by prior macrophage depletion, consistent with clinical data that implicate IL-6 in this pathogenic event. These data demonstrate that CAR-induced cytokine release syndrome can be modeled in mice that express target Ag in an appropriate distribution. Furthermore, our findings argue that ErbB-retargeted T cells can achieve therapeutic benefit in the absence of unacceptable toxicity, providing that route of administration and dose are carefully optimized.

Effect of EGFR inhibition on HER3/PI3K activation by feedback induction of ErbB heterodimers in cetuximab-sensitive colon cancer cells.

3626 Background: Although cetuximab treatment has been successful for the treatment of KRAS wild-type colorectal cancers, complete remissions are rarely seen in patients, leading ultimately to resistance. We hypothesized that in cetuximab-sensitive patients, the ErbB network is insufficiently targeted since network plasticity may occur. Methods: We have used EGFR-sensitive colorectal cancer cells and investigated ErbB network activity and adaptations by RTK arrays, western blot, and Collaborative Enzyme Enhance Reactive immunoassay (CEER). These were complemented by ErbB heterodimerization (HER2:3, HER1:2, HER1:3, HER3:PI3K) assays using CEER. Effects on cell survival were measured using colony formation assay. In addition to the EGFR sensitive cell line, 200 clinical colorectal cancer (CRC) samples were profiled utilizing CEER for RTKs, downstream signaling, and heterodimerization. Results: EGFR and downstream signaling proteins AKT, ERK, and RSK were potently inhibited by cetuximab or gefitinib at 24h of treatment in EGFR sensitive colorectal cancer cell line. At 24h of treatment, we observed approximately 2 folds increase in total HER2 and HER3 protein levels, 2.7 folds in phosphorylated HER3, and 5.4 folds in HER2:HER3 heterodimer formation. Concurrently, increased in ErbB heterodimer formation was accompanied by 5 folds increase in PI3K binding to HER3, resulting in enhanced HER3 signaling, with increase in AKT, ERK, and RSK. Co-treatment of these cells with cetuximab and HER2 inhibitor Trastuzumab or by treatment with lapatinib blocked the induction of HER2:HER3 heterodimer, HER3 phosphorylation, and PI3K binding to HER3. In 30% of the 200 clinical colorectal cancer samples profiled, we observed an increased in phosphorylated HER3, formation of HER2:HER3 and HER3:PI3K heterodimers along with HER1 activation (KRAS WT). Conclusions: Combination of HER2 inhibitor with an EGFR inhibitor could potentially increase the therapeutic index in cetuximab sensitive patients, and suppress activation of feedback mechanisms upon EGFR inhibition. Current findings suggest that CRC patients with similar profile would benefit from these combination therapies.

Abstract 1072: MM-121/SAR256212, an anti-ErbB3 antibody, restores sensitivity to letrozole and delays the onset of resistance in an ER+ breast cancer model.

Abstract Endocrine therapies directed against estrogen action are initially effective in estrogen-receptor positive (ER+) breast cancer, though most patients will eventually develop resistance to these treatments. It has recently been shown that growth factor signaling can activate ER through the AKT and MAPK signaling pathways. Moreover, both heregulin and ErbB3 signaling have been implicated as potential escape routes in the development of resistance to anti-estrogen therapies. Here we have used an in vivo model of ER+ breast cancer to investigate the activity of MM-121/SAR256212, alone and in combination with the aromatase inhibitor letrozole. Tumor xenografts of human breast cancer cells (MCF-7) engineered to express aromatase (MCF7-Ca) were generated in ovariectomized athymic nude mice. Mice were injected daily with androstenedione and randomized to treatment groups once the average tumor volume per group reached ∼300 mm3. Mice received vehicle, letrozole, MM-121, or both MM-121 and letrozole. Following development of resistance to letrozole, mice receiving letrozole alone were re-distributed into three treatment groups - letrozole, MM-121, or letrozole plus MM-121. Tumors were harvested at 24 h post-treatment initiation, at development of letrozole resistance, and at the end of study. Total and phosphorylated levels of certain signaling proteins in the ErbB network were measured by quantitative Western blotting. MM-121 in combination with letrozole significantly inhibited tumor growth (p<0.05) in our in vivo model. Further, when MM-121 was dosed with letrozole from the start of the study, a statistically significant delay was observed in the onset of resistance to letrozole (p=0.01; Letrozole vs. Let+MM-121/SAR256212). Following development of letrozole resistance, the addition of MM-121 restored sensitivity to letrozole and slowed the rate of tumor growth (p<0.0001; Letrozole vs. Let to Let+MM-121/SAR256212). Molecular analyses indicated decreased tErbB3 and pErbB3 levels in MM-121/SAR256212 treated tumors. As previously shown, tHER2 levels were elevated following development of letrozole resistance. Moreover, pS6 levels were decreased following continuous MM-121/SAR256212 and letrozole treatment, indicating decreased mRNA translation. In conclusion, MM-121 delayed the onset of resistance to letrozole in this in vivo model, and re-sensitized tumors to letrozole upon development of resistance. These data indicate a potential role for combining MM-121 with letrozole in first and second line treatment of ER+ breast cancer. Citation Format: Michael D. Curley, Gauri Sabnis, Lucia Wille, Gabriela Garcia, Victor Moyo, Armina Kazi, Gavin MacBeath, Angela Brodie. MM-121/SAR256212, an anti-ErbB3 antibody, restores sensitivity to letrozole and delays the onset of resistance in an ER+ breast cancer model. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1072. doi:10.1158/1538-7445.AM2013-1072