A phase I dose-escalation study of pulsatile afatinib in patients with recurrent or progressive brain cancer

Background

Afatinib (BIBW2992; Gilotrif®) is a selective and irreversible inhibitor of the epidermal growth factor receptor (ErbB; EGFR) family. It inhibits EGFR, HER2, and HER4 phosphorylation, resulting in tumor growth inhibition and regression. This phase I dose-escalation trial of pulsatile afatinib examined the safety, drug penetration into the central nervous system, preliminary antitumor activity, and recommended phase II dose in patients with progressive or recurrent brain cancers.

Methods

Afatinib was taken orally once every 4 days or once every 7 days depending on dose cohort, until disease progression or unacceptable toxicity.

Results

A total of 24 patients received the investigational agent and were evaluable for safety analyses, and 21 patients were evaluable for efficacy. Dosing was administered at 80 mg every 4 days, 120 mg every 4 days, 180 mg every 4 days, or 280 mg every 7 days. A recommended phase II dose of pulsatile afatinib was established at 280 mg every 7 days as there were no dose-limiting toxicities in any of the dosing cohorts and all toxicities were deemed manageable. The most common drug-related toxicities were diarrhea, rash, nausea, vomiting, fatigue, stomatitis, pruritus, and limb edema. Out of the 21 patients evaluable for efficacy, 2 patients (9.5%) exhibited partial response based on Response Assessment in Neuro-Oncology criteria and disease stabilization was seen in 3 patients (14.3%).

Conclusions

Afatinib taken orally was safe and well-tolerated up to 280 mg every 7 days in brain cancer patients.

Parvalbumin interneurons dysfunction is potentially associated with FαMNs decrease and NRG1-ErbB4 signaling inhibition in spinal cord in amyotrophic lateral sclerosis

OBJECTIVE

To investigate the alteration of PV interneurons in ALS mainly focusing its dynamic changes and its relationship with motor neurons and ErbB4 signaling.

METHODS

SOD1G93A mice were used as ALS model. ALS animals were divided into different groups according to birth age: symptomatic prophase (50~60 days), symptomatic phase (90~100 days), and symptomatic progression (130~140 days). Immunofluorescence was performed for measurement of PV-positive interneurons, MMP-9, ChAT, NeuN and ErbB4. RT-qPCR and western blot were used to determine the expression of PV and MMP-9.

RESULTS

PV expression was remarkably higher in the anterior horn of gray matter compared with posterior horn and area in the middle of gray matter in control mice. In ALS mice, PV, MMP-9 and ErbB4 levels were gradually decreased along with onset. PV, MMP-9 and ErbB4 levels in ALS mice were significantly down-regulated than control mice after onset, indicating the alteration of PV interneurons, FαMNs and ErbB4. SαMNs levels only decreased remarkably at symptomatic progression in ALS mice compared with control mice, while γMNs levels showed no significant change during whole period in all mice. MMP-9 and ErbB4 were positively correlated with PV. NRG1 treatment significantly enhanced the expression of ErBb4, PV and MMP-9 in ALS mice.

CONCLUSION

PV interneurons decrease is along with FαMNs and ErbB4 decrease in ALS mice.

miR-135a-5p overexpression in peripheral blood-derived exosomes mediates vascular injury in type 2 diabetes patients

Objective

Diabetes pathology relies on exosomes (Exos). This study investigated how peripheral blood Exo-containing microRNAs (miRNAs) cause vascular injury in type 2 diabetes (T2D).

Methods

We removed DEmiRNA from T2D chip data from the GEO database. We isolated Exo from 15 peripheral blood samples from T2D patients and 15 healthy controls and measured Exo DEmiRNA levels. We employed the intersection of Geneards and mirWALK database queries to find T2D peripheral blood mRNA-related chip target genes. Next, we created a STRING database candidate target gene interaction network map. Next, we performed GO and KEGG enrichment analysis on T2D-related potential target genes using the ClusterProfiler R package. Finally, we selected T2D vascular damage core genes and signaling pathways using GSEA and PPI analysis. Finally, we used HEK293 cells for luciferase assays, co-cultured T2D peripheral blood-derived Exo with HVSMC, and detected HVSMC movement alterations.

Results

We found 12 T2D-related DEmiRNAs in GEO. T2D patient-derived peripheral blood Exo exhibited significantly up-regulated miR-135a-3p by qRT-PCR. Next, we projected miR-135a-3p's downstream target mRNA and screened 715 DEmRNAs to create a regulatory network diagram. DEmRNAs regulated biological enzyme activity and vascular endothelial cells according to GO function and KEGG pathway analysis. ErbB signaling pathway differences stood out. PPI network study demonstrated that DEmRNA ATM genes regulate the ErbB signaling pathway. The luciferase experiment validated miR-135a-3p and ATM target-binding. Co-culture of T2D patient-derived peripheral blood Exo with HVSMC cells increases HVSMC migration, ErbB2, Bcl-2, and VEGF production, and decreases BAX and ATM. However, miR-135a-3p can reverse the production of the aforesaid functional proteins and impair HVSMC cell movement.

Conclusion

T2D patient-derived peripheral blood Exo carrying miR-135a-3p enter HVSMC, possibly targeting and inhibiting ATM, activating the ErbB signaling pathway, promoting abnormal HVSMC proliferation and migration, and aggravating vascular damage.

Compensatory role of neuregulin-1 in diabetic cardiomyopathy

Diabetes mellitus is a prevalent risk factor for congestive heart failure. Diabetic cardiomyopathy patients present with left ventricular (LV) diastolic dysfunction at an early stage, then systolic dysfunction as the disease progresses. The mechanism underlying the development of diabetic cardiomyopathy has not yet been fully understood. This study aimed to elucidate the mechanisms by which diastolic dysfunction precedes systolic dysfunction at the early stage of diabetic cardiomyopathy. We hypothesized that the downregulation of cardioprotective factors is involved in the pathogenesis of diabetic cardiomyopathy. LV diastolic dysfunction, but not systolic dysfunction, was observed in type-1 diabetes mellitus model mice 4 weeks after STZ administration (STZ-4W), mimicking the early stage of diabetic cardiomyopathy. Counter to expectations, neuregulin-1 (NRG1) was markedly upregulated in the vascular endothelial cell in the ventricles of STZ-4W mice. To clarify the functional significance of the upregulated NRG1, we blocked its receptor ErbB2 with trastuzumab (TRZ). In STZ-4W mice, TRZ significantly reduced the systolic function without affecting diastolic function and caused a more prominent reduction in Akt phosphorylation levels. These results indicate that the compensatory upregulated NRG1 contributes to maintaining the LV systolic function, which explains why diastolic dysfunction precedes systolic dysfunction at the early stage of diabetic cardiomyopathy.

Synergism of the receptor tyrosine kinase Axl with ErbB receptors mediates resistance to regorafenib in hepatocellular carcinoma

Introduction

Hepatocellular carcinoma (HCC) patients at advanced stages receive immunotherapy or treatment with tyrosine kinase inhibitors (TKIs) such as Sorafenib (Sora) or Lenvatinib in frontline as well as Regorafenib (Rego) or Cabozantinib in second-line. A major hindrance of TKI therapies is the development of resistance, which renders drug treatment futile and results in HCC progression.

Methods

In this study, we addressed the impact of the receptor tyrosine kinase Axl binding to its ligand Gas6 in acquiring refractoriness to TKIs. The initial responses of Axl-positive and Axl-negative cell lines to different TKIs were assessed. Upon inducing resistance, RNA-Seq, gain- and loss-of-function studies were applied to understand and intervene with the molecular basis of refractoriness. Secretome analysis was performed to identify potential biomarkers of resistance.

Results

We show that HCC cells exhibiting a mesenchymal-like phenotype were less sensitive to drug treatment, linking TKI resistance to changes in epithelial plasticity. Gas6/Axl expression and activation were upregulated in Rego-resistant HCC cells together with the induction of ErbB receptors, whereas HCC cells lacking Axl failed to stimulate ErbBs. Treatment of Rego-insensitive HCC cells with the pan-ErbB family inhibitor Afatinib rather than with Erlotinib blocking ErbB1 reduced cell viability and clonogenicity. Genetic intervention with ErbB2-4 but not ErbB1 confirmed their crucial involvement in refractoriness to Rego. Furthermore, Rego-resistant HCC cells secreted basic fibroblast growth factor (bFGF) depending on Axl expression. HCC patients treated with Sora in first-line and with Rego in second-line displayed elevated serum levels of bFGF, emphasizing bFGF as a predictive biomarker of TKI treatment.

Discussion

Together, these data suggest that the inhibition of ErbBs is synthetic lethal with Rego in Axl-expressing HCC cells, showing a novel vulnerability of HCC.

Non-equilibrium modalities of inhibition: Characterizing irreversible inhibition for the ErbB receptor family members

Most drug target interactions for clinically approved small-molecules are non-equilibrium slow-onset, tight-binding or irreversible in nature, with pronounced element of time-dependence of inhibition. Analysis of such modality of inhibition requires a continuous enzyme kinetic measurement that can yield complete progress curves and an automated high-throughput analysis pipeline. Given the increasing emphasis on designing non-equilibrium modes of inhibiting an enzyme target (especially irreversible), the above specified pipeline for data generation and analysis is essential for extracting parameters to guide decisions in early drug discovery. In this manuscript, the methodology and data analysis protocol from our irreversible inhibitor characterization campaigns for the ErbB receptor family members is presented. Guidance is provided on the appropriate design of assay to generate quality data, setting up the analysis and estimation of inactivation rate (kinact) and the pseudo-equilibrium binding affinity (KI) constant (or their ratio kinact/KI) in a high-throughput manner for the inhibitor interacting with the protein target of interest.

Refractory microsatellite stable metastatic colorectal cancer with ERBB2/ERBB3 mutation may be preferred population for regorafenib plus PD-1 inhibitor therapy: a real-world study

Background

Microsatellite stable (MSS) colorectal cancer (CRC) has been referred to as the "cold tumor" because of almost no response to anti-programmed death-1 (PD-1) antibody. A recent REGONIVO trial showed that regorafenib plus nivolumab had an encouraging efficacy in MSS metastatic CRC (mCRC). However, only a small subset of patients may benefit from the combination therapy. We aim to evaluate the efficacy and safety data of immune checkpoint inhibitors combined with regorafenib in refractory MSS mCRC and to discover biomarkers that can effectively stratify the beneficial patient population.

Methods

We retrospectively analyzed patients with MSS mCRC who received regorafenib combined with anti-PD-1 antibody therapy. The objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and status of gene mutation were reviewed and evaluated.

Results

Twenty-one patients received combination treatment. At a median treatment duration of 4 months, one patient achieved complete response, three patients achieved partial response, and two patients achieved stable disease as the best response. The ORR and DCR were 19% and 28.5% in the overall population, respectively. The median PFS was 4 months, and the median OS was 25 months. Only erbb2 receptor tyrosine kinase 2/erbb3 receptor tyrosine kinase 3 (ERBB2/ERBB3) mutation status was confirmed to be a potential predictive factor for effective treatment. In patients with ERBB2/ERBB3 mutation, ORR, DCR, and PFS exhibited significant improvements in comparison with that in wild-type patients. Grade 3 or higher treatment-related adverse events occurred in three patients (14.3%).

Conclusions

Regorafenib in combination with PD-1 inhibitor provides a feasible treatment regimen for refractory MSS mCRC with tolerated toxicity. Patients with ERBB2/ERBB3 mutation may be the preferred population for this combination regimen.

Knockout of all ErbB-family genes delineates their roles in proliferation, survival and migration

The ErbB-family receptors play pivotal roles in the proliferation, migration and survival of epithelial cells. Because our knowledge on the ErbB-family receptors has been largely obtained by the exogenous application of their ligands, it remains unknown to what extent each of the ErbB members contributes to these outputs. We here knocked out each ErbB gene, various combinations of ErbB genes or all ErbB genes in Madin-Darby canine kidney cells to delineate the contribution of each gene. ERK1 and ERK2 (ERK1/2, also known as MAPK3 and MAPK1, respectively) activation waves during collective cell migration were mediated primarily by ErbB1 and secondarily by the ErbB2 and ErbB3 heterodimer. Either ErbB1 or the ErbB2 and ErbB3 complex was sufficient for the G1/S progression. The saturation cell density was markedly reduced in cells deficient in all ErbB proteins, but not in cells retaining only ErbB2, which cannot bind to ligands. Thus, a ligand-independent ErbB2 activity is sufficient for preventing apoptosis at high cell density. In short, systematic knockout of ErbB-family genes has delineated the roles of each ErbB receptor.

Does EGFR Signaling Mediate Orexin System Activity in Sleep Initiation?

Sleep-wake cycle disorders are an important symptom of many neurological diseases, including Parkinson's disease, Alzheimer's disease, and multiple sclerosis. Circadian rhythms and sleep-wake cycles play a key role in maintaining the health of organisms. To date, these processes are still poorly understood and, therefore, need more detailed elucidation. The sleep process has been extensively studied in vertebrates, such as mammals and, to a lesser extent, in invertebrates. A complex, multi-step interaction of homeostatic processes and neurotransmitters provides the sleep-wake cycle. Many other regulatory molecules are also involved in the cycle regulation, but their functions remain largely unclear. One of these signaling systems is epidermal growth factor receptor (EGFR), which regulates the activity of neurons in the modulation of the sleep-wake cycle in vertebrates. We have evaluated the possible role of the EGFR signaling pathway in the molecular regulation of sleep. Understanding the molecular mechanisms that underlie sleep-wake regulation will provide critical insight into the fundamental regulatory functions of the brain. New findings of sleep-regulatory pathways may provide new drug targets and approaches for the treatment of sleep-related diseases.

Low-intensity pulsed ultrasound promotes proliferation and myelinating genes expression of Schwann cells through NRG1/ErbB signaling pathway

Schwann cells (SCs) are the major component of myelin sheath in the peripheral nervous system, which are necessary in the development, function maintenance, and repair of peripheral nerves. This study aimed to investigate the potential mechanism of low-intensity pulsed ultrasound (LIPUS) affecting the proliferation and myelinating activity of SCs. Rat Schwann cell line RSC96 were cultured and exposed to LIPUS of different duty ratios (control, 20 %, 50 %, 80 %). Results demonstrated that LIPUS with a duty ratio of 50 % showing the maximal effect in facilitating proliferation of SCs. The expressions of Krox20 and myelin basic protein (MBP), the key molecules of SC myelination, and the potent inducer of myelination neuregulin 1 (NRG1) and its receptors ErbB2 and ErbB3 increased significantly by LIPUS. The reaction of these factors to LIPUS were both time- and duty ratio-dependent: namely LIPUS with higher duty ratios took effects when applied repeatedly over more consecutive days. These observations indicated that NRG1/ErbB signaling pathway might contribute to the effects of LIPUS on the proliferation and myelinating status of SCs, which could be one of the mechanisms in the protective role of LIPUS in nerve repair and regeneration. Our work provided novel insights for promising strategies of nerve repair therapy.

Design and selection of optimal ErbB-targeting bispecific antibodies in pancreatic cancer

The ErbB family of receptor tyrosine kinases is a primary target for small molecules and antibodies for pancreatic cancer treatment. Nonetheless, the current treatments for this tumor are not optimal due to lack of efficacy, resistance, or toxicity. Here, using the novel BiXAb™ tetravalent format platform, we generated bispecific antibodies against EGFR, HER2, or HER3 by considering rational epitope combinations. We then screened these bispecific antibodies and compared them with the parental single antibodies and antibody pair combinations. The screen readouts included measuring binding to the cognate receptors (mono and bispecificity), intracellular phosphorylation signaling, cell proliferation, apoptosis and receptor expression, and also immune system engagement assays (antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity). Among the 30 BiXAbs™ tested, we selected 3Patri-1Cetu-Fc, 3Patri-1Matu-Fc and 3Patri-2Trastu-Fc as lead candidates. The in vivo testing of these three highly efficient bispecific antibodies against EGFR and HER2 or HER3 in pre-clinical mouse models of pancreatic cancer showed deep antibody penetration in these dense tumors and robust tumor growth reduction. Application of such semi-rational/semi-empirical approach, which includes various immunological assays to compare pre-selected antibodies and their combinations with bispecific antibodies, represents the first attempt to identify potent bispecific antibodies against ErbB family members in pancreatic cancer.

An Innovative PTD-IVT-mRNA Delivery Platform for CAR Immunotherapy of ErbB(+) Solid Tumor Neoplastic Cells

Chimeric antigen receptor (CAR) immunotherapy includes the genetic modification of immune cells to carry such a receptor and, thus, recognize cancer cell surface antigens. Viral transfection is currently the preferred method, but it carries the risk of off-target mutagenicity. Other transfection platforms have thus been proposed, such the in vitro transcribed (IVT)-mRNAs. In this study, we exploited our innovative, patented delivery platform to produce protein transduction domain (PTD)-IVT-mRNAs for the expression of CAR on NK-92 cells. CAR T1E-engineered NK-92 cells, harboring the sequence of T1E single-chain fragment variant (scFv) to recognize the ErbB receptor, bearing either CD28 or 4-1BB as co-stimulatory signaling domains, were prepared and assessed for their effectiveness in two different ErbB(+) cancer cell lines. Our results showed that the PTD-IVT-mRNA of CAR was safely transduced and expressed into NK-92 cells. CAR T1E-engineered NK-92 cells provoked high levels of cell death (25-33%) as effector cells against both HSC-3 (oral squamous carcinoma) and MCF-7 (breast metastatic adenocarcinoma) human cells in the co-incubation assays. In conclusion, the application of our novel PTD-IVT-mRNA delivery platform to NK-92 cells gave promising results towards future CAR immunotherapy approaches.

An ErbB Lineage Co-Regulon Harbors Potentially Co-Druggable Targets for Multimodal Precision Therapy in Head and Neck Squamous Cell Carcinoma

The ErbB lineage of oncogenic receptor tyrosine kinases is frequently overexpressed in head and neck squamous cell carcinomas. A common co-regulon triggered by the ErbB proteins; involving shared signaling circuitries; may harbor co-druggable targets or response biomarkers for potential future multimodal precision therapy in ErbB-driven head and neck squamous cell carcinoma. We here present a cohort-based; genome-wide analysis of 488 head and neck squamous cell carcinomas curated as part of The Cancer Genome Atlas Project to characterize genes that are significantly positively co-regulated with the four ErbB proteins and those that are shared among all ErbBs denoting a common ErbB co-regulon. Significant positive gene correlations involved hundreds of genes that were co-expressed with the four ErbB family members (q < 0.05). A common; overlapping co-regulon consisted of a core set of 268 genes that were uniformly co-regulated with all four ErbB genes and highly enriched for functions in chromatin organization and histone modifications. This high-priority set of genes contained ten putative antineoplastic drug-gene interactions. The nature and directionality of these ten drug-gene associations was an inhibiting interaction for seven (PIK3CB; PIK3C2B; HDAC4; FRK; PRKCE; EPHA4; and DYRK1A) of them in which the drug decreases the biological activity or expression of the gene target. For three (CHD4; ARID1A; and PBRM1) of the associations; the directionality of the interaction was such that the gene predicted sensitivit y to the drug suggesting utility as potential response biomarkers. Drug-gene interactions that predicted the gene product to be reduced by the drug included a variety of potential targeted molecular agent classes. This unbiased genome-wide analysis identified a target-rich environment for multimodal therapeutic approaches in tumors that are putatively ErbB-driven. The results of this study require preclinical validation before ultimately devising lines of combinatorial treatment strategies for ErbB-dependent head and neck squamous cell carcinomas that incorporate these findings.

The Pan-ErbB tyrosine kinase inhibitor afatinib inhibits multiple steps of the mammarenavirus life cycle

The mammarenavirus Lassa virus (LASV) causes a life-threatening acute febrile disease, Lassa fever (LF). To date, no US Food and Drug Administration (FDA)-licensed medical countermeasures against LASV are available. This underscores the need for the development of novel anti-LASV drugs. Here, we screen an FDA-approved drug library to identify novel anti-LASV drug candidates using an infectious-free cell line expressing a functional LASV ribonucleoprotein (vRNP), where levels of vRNP-directed reporter gene expression serve as a surrogate for vRNP activity. Our screen identified the pan-ErbB tyrosine kinase inhibitor afatinib as a potent inhibitor of LASV vRNP activity. Afatinib inhibited multiplication of lymphocytic choriomeningitis virus (LCMV) a mammarenavirus closely related to LASV. Cell-based assays revealed that afatinib inhibited multiple steps of the LASV and LCMV life cycles. Afatinib also inhibited multiplication of Junín virus vaccine strain Candid#1, indicating that afatinib can have antiviral activity against a broad range of human pathogenic mammarenaviruses.

Aberrant Neuregulin 1/ErbB Signaling in Charcot-Marie-Tooth Type 4D Disease

Charcot-Marie-Tooth type 4D (CMT4D) is an autosomal recessive demyelinating form of CMT characterized by progressive motor and sensory neuropathy. N-myc downstream regulated gene 1 (NDRG1) is the causative gene for CMT4D. Although more CMT4D cases have been reported, the comprehensive molecular mechanism underlying CMT4D remains elusive. Here, we generated a novel knockout mouse model in which the fourth and fifth exons of the Ndrg1 gene were removed. Ndrg1-deficient mice develop early progressive demyelinating neuropathy and limb muscle weakness. The expression pattern of myelination-related transcriptional factors, including SOX10, OCT6, and EGR2, was abnormal in Ndrg1-deficient mice. We further investigated the activation of the ErbB2/3 receptor tyrosine kinases in Ndrg1-deficient sciatic nerves, as these proteins play essential roles in Schwann cell myelination. In the absence of NDRG1, although the total ErbB2/3 receptors expressed by Schwann cells were significantly increased, levels of the phosphorylated forms of ErbB2/3 and their downstream signaling cascades were decreased. This change was not associated with the level of the neuregulin 1 ligand, which was increased in Ndrg1-deficient mice. In addition, the integrin β4 receptor, which interacts with ErbB2/3 and positively regulates neuregulin 1/ErbB signaling, was significantly reduced in the Ndrg1-deficient nerve. In conclusion, our data suggest that the demyelinating phenotype of CMT4D disease is at least in part a consequence of molecular defects in neuregulin 1/ErbB signaling.

The HER family as therapeutic targets in colorectal cancer

The human epidermal growth factor receptor (HER, ErbB) family has four members, epidermal growth factor receptor (EGFR), HER2, HER3, and HER4. Although distinct in ligands and functions, all of the HER family members are receptor tyrosine kinases playing important roles in the pathogenesis of cancers. In the era of precision medicine, the HER family is one of the most important and successful cancer therapeutic targets, hallmarked by the approval of anti-EGFR therapies for the treatment of colorectal cancer and non-small cell lung cancer, and anti-HER2 therapies for the treatment of breast cancer and gastric cancer. This review briefly discusses how HER family members were discovered, their functions and roles in cancer, and most importantly, the developmental history and recent updates of therapies targeting HER family members, with colorectal cancer as a focus. We also discussed the patient selection and drug resistance to anti-EGFR therapies in the treatment of colorectal cancer.

Epidermal Growth Factor Pathway in the Age-Related Decline of Oligodendrocyte Regeneration

Oligodendrocytes (OLs) are specialized glial cells that myelinate CNS axons. OLs are generated throughout life from oligodendrocyte progenitor cells (OPCs) via a series of tightly controlled differentiation steps. Life-long myelination is essential for learning and to replace myelin lost in age-related pathologies such as Alzheimer's disease (AD) as well as white matter pathologies such as multiple sclerosis (MS). Notably, there is considerable myelin loss in the aging brain, which is accelerated in AD and underpins the failure of remyelination in secondary progressive MS. An important factor in age-related myelin loss is a marked decrease in the regenerative capacity of OPCs. In this review, we will contextualize recent advances in the key role of Epidermal Growth Factor (EGF) signaling in regulating multiple biological pathways in oligodendroglia that are dysregulated in aging.

Oncogenic Neuregulin 1 gene (NRG1) fusions in cancer: A potential new therapeutic opportunities

It is widely established that chromosomal rearrangements induce oncogenesis in solid tumors. However, discovering chromosomal rearrangements that are targetable and actionable remains a difficulty. Targeting gene fusion or chromosomal rearrangement seems to be a powerful strategy to address malignancies characterized by gene rearrangement. Oncogenic NRG1 fusions are relatively rare drivers that infrequently occur across most tumor types. NRG1 fusions exhibit unique biological properties and are difficult to identify owing to their large intronic regions. NRG1 fusions can be detected using a variety of techniques, including fluorescence in situ hybridization, immunohistochemistry, or next-generation sequencing (NGS), with NGS-based RNA sequencing being the most sensitive. Previous studies have shown that NRG1 fusion protein induces tumorigenesis, and numerous therapies targeting the ErbB signaling pathway, such as ErbB kinase inhibitors and monoclonal antibodies, have initially demonstrated encouraging anticancer efficacy in malignant tumors carrying NRG1 fusions. In this review, we present the characteristics and prevalence of NRG1 fusions in solid tumors. Additionally, we discuss the laboratory approaches for diagnosing NRG1 gene fusions. More importantly, we outline promising strategies for treating malignancies with NRG1 fusion.

Apelin signaling dependent endocardial protrusions promote cardiac trabeculation in zebrafish

During cardiac development, endocardial cells (EdCs) produce growth factors to promote myocardial morphogenesis and growth. In particular, EdCs produce neuregulin which is required for ventricular cardiomyocytes (CMs) to seed the multicellular ridges known as trabeculae. Defects in neuregulin signaling, or in endocardial sprouting toward CMs, cause hypotrabeculation. However, the mechanisms underlying endocardial sprouting remain largely unknown. Here, we first show by live imaging in zebrafish embryos that EdCs interact with CMs via dynamic membrane protrusions. After touching CMs, these protrusions remain in close contact with their target despite the vigorous cardiac contractions. Loss of the CM-derived peptide Apelin, or of the Apelin receptor, which is expressed in EdCs, leads to reduced endocardial sprouting and hypotrabeculation. Mechanistically, neuregulin signaling requires endocardial protrusions to induce extracellular signal-regulated kinase (Erk) activity in CMs and trigger their delamination. Altogether, these data show that Apelin signaling-dependent endocardial protrusions modulate CM behavior during trabeculation.

Afatinib alone and in combination with vinorelbine or paclitaxel, in patients with HER2-positive breast cancer who failed or progressed on prior trastuzumab and/or lapatinib (LUX-Breast 2): an open-label, multicenter, phase II trial

Purpose

Resistance to HER2 (ErbB2)-targeted therapy may be mediated by other members of the ErbB family. We investigated the efficacy and safety of the irreversible ErbB family blocker, afatinib, alone as first-line therapy in the advanced setting and in combination with vinorelbine or paclitaxel for those who progressed on afatinib monotherapy, in female patients with metastatic breast cancer who had failed or progressed on prior HER2-targeted therapy in the early disease setting.

Methods

In this phase II, single-arm, two-part study (ClinicalTrials.gov: NCT01271725), patients in part A received afatinib 40 mg/day in 21-day cycles until disease progression or intolerable adverse events (AEs). Patients with progressive disease could then receive afatinib plus weekly vinorelbine 25 mg/m² or paclitaxel 80 mg/m² until disease progression or intolerable AEs (part B). The primary endpoint was confirmed objective response rate (RECIST v1.1).

Results

Eighty-seven patients were enrolled and 74 were treated in part A (median age: 51 years [range 27–76]; 31 [42%] estrogen receptor-positive, 26 [35%] progesterone receptor-positive). Of these, 39 (53%) patients went on to receive afatinib plus vinorelbine (13 patients) or paclitaxel (26 patients) in part B. Thirteen (18%) and 12 (31%) patients achieved an objective response in parts A and B, respectively. The most common treatment-related AEs with afatinib monotherapy (any/grade ≥ 3) were diarrhea (68%/8%) and rash (49%/4%). Combination therapy was generally well tolerated, with no additive toxicity observed.

Conclusion

Afatinib treatment, alone or in combination with vinorelbine or paclitaxel, was associated with objective responses in ≥ 18% of patients with metastatic breast cancer for whom prior HER2-targeted therapy has failed. Treatment-related AEs were generally manageable, with few grade ≥ 3 AEs reported.

Trial registration

ClinicalTrials.gov, NCT01271725, registered 1 July 2011.

Recent advances and limitations in the application of kahalalides for the control of cancer

Since the discovery of the kahalalide family of marine depsipeptides in 1993, considerable work has been done to develop these compounds as new and biologically distinct anti-cancer agents. Clinical trials and laboratory research have yielded a wealth of data that indicates tolerance of kahalalides in healthy cells and selective activity against diseased cells. Currently, two molecules have attracted the greates level of attention, kahalalide F (KF) and isokahalalide F (isoKF, Irvalec, PM 02734, elisidepsin). Both compounds were originally isolated from the sarcoglossan mollusk Elysia rufescens but due to distinct structural characteristics it has been hypothesized and recently shown that the ultimate origin of the molecules is microbial. The search for their true source has been a subject of considerable research in the anticipation of finding new analogs and a culturable expression system that can produce sufficient material through fermentation to be industrially relevant.

Tfap2b specifies an embryonic melanocyte stem cell that retains adult multifate potential

Melanocytes, the pigment-producing cells, are replenished from multiple stem cell niches in adult tissue. Although pigmentation traits are known risk factors for melanoma, we know little about melanocyte stem cell (McSC) populations other than hair follicle McSCs and lack key lineage markers with which to identify McSCs and study their function. Here we find that Tfap2b and a select set of target genes specify an McSC population at the dorsal root ganglia in zebrafish. Functionally, Tfap2b is required for only a few late-stage embryonic melanocytes, and is essential for McSC-dependent melanocyte regeneration. Fate mapping data reveal that tfap2b⁺ McSCs have multifate potential, and are the cells of origin for large patches of adult melanocytes, two other pigment cell types (iridophores and xanthophores), and nerve-associated cells. Hence, Tfap2b confers McSC identity in early development, distinguishing McSCs from other neural crest and pigment cell lineages, and retains multifate potential in the adult zebrafish.

NCOA3 is a critical oncogene in thyroid cancer via the modulation of major signaling pathways

PURPOSE

The Nuclear Receptor Coactivator (NCOA3, also known as SRC-3, AIB1, p/CIP, RAC3, ACTR, and TRAM1), acts as an oncogene in multiple tumors, but its biological function in thyroid cancer remains unclear. This study was designed to explore the role of NCOA3 in thyroid cancer.

METHODS

The study assessed NCOA3 expression in thyroid cancer and their matched non-cancerous thyroid tissues at mRNA and protein levels. Then we evaluated the effect of NCOA3 on malignant activities of thyroid cancer cells. To better understand the oncogenic role of NCOA3 in thyroid tumorigenesis, we tested the effect of NCOA3 on major proteins related to thyroid cancer.

RESULTS

Our data demonstrated that protein expression of NCOA3 was significantly upregulated in thyroid cancer tissues. NCOA3 knockdown inhibited cell proliferation and invasion, and induced cell cycle arrest and apoptosis in thyroid cancer. Conversely, ectopic expression of NCOA3 promoted cell proliferation and invasiveness in thyroid cancer. Mechanistically, NCOA3 could improve the survival and invasiveness of thyroid cancer cells through the modulation of the ErbB, AKT, ERK, and β-catenin pathways.

CONCLUSION

Collectively, these findings suggest that NCOA3 is critical in the initiation and development of thyroid cancer, and might be a possible marker for prognosis and therapy.

Expanding the Disorder-Function Paradigm in the C-Terminal Tails of Erbbs

ErbBs are receptor tyrosine kinases involved not only in development, but also in a wide variety of diseases, particularly cancer. Their extracellular, transmembrane, juxtamembrane, and kinase folded domains were described extensively over the past 20 years, structurally and functionally. However, their whole C-terminal tails (CTs) following the kinase domain were only described at atomic resolution in the last 4 years. They were shown to be intrinsically disordered. The CTs are known to be tyrosine-phosphorylated when the activated homo- or hetero-dimers of ErbBs are formed. Their phosphorylation triggers interaction with phosphotyrosine binding (PTB) or Src Homology 2 (SH2) domains and activates several signaling pathways controling cellular motility, proliferation, adhesion, and apoptosis. Beyond this passive role of phosphorylated domain and site display for partners, recent structural and function studies unveiled active roles in regulation of phosphorylation and interaction: the CT regulates activity of the kinase domain; different phosphorylation states have different compaction levels, potentially modulating the succession of phosphorylation events; and prolines have an important role in structure, dynamics, and possibly regulatory interactions. Here, we review both the canonical role of the disordered CT domains of ErbBs as phosphotyrosine display domains and the recent findings that expand the known range of their regulation functions linked to specific structural and dynamic features.

Receptor Tyrosine Kinases as Candidate Prognostic Biomarkers and Therapeutic Targets in Meningioma

Meningioma (MGM) is the most common type of intracranial tumor in adults. The validation of novel prognostic biomarkers to better inform tumor stratification and clinical prognosis is urgently needed. Many molecular and cellular alterations have been described in MGM tumors over the past few years, providing a rational basis for the identification of biomarkers and therapeutic targets. The role of receptor tyrosine kinases (RTKs) as oncogenes, including those of the ErbB family of receptors, has been well established in several cancer types. Here, we review histological, molecular, and clinical evidence suggesting that RTKs, including the epidermal growth factor receptor (EGFR, ErbB1), as well as other members of the ErbB family, may be useful as biomarkers and therapeutic targets in MGM.

Neu Perspectives, Therapies, and Challenges for Metastatic HER2-Positive Breast Cancer

Even though gene amplification or protein overexpression occurs in approximately one-fifth of all breast cancers, the discovery of HER2 has, nevertheless, had profound implications for the disease. Indeed, the characterization of the receptor resulted in a number of significant advances. Structurally, unique features provided avenues for the development of numerous compounds with target-specificity; molecularly, biological constructs revealed a highly complex, internal signal transduction pathway with regulatory effects on tumor proliferation, survival, and perhaps, even resistance; and clinically, disease outcomes manifested its predictive and prognostic value. Yet despite the receptor’s utility, the beneficial effects are diminished by tumor recurrence after neo- or adjuvant therapy as well as losses resulting from the inability to cure patients with metastatic disease. What these observations suggest is that while tumor response may be partially linked to uncoupling cell surface message reception and nuclear gene expression, as well as recruitment of the innate immune system, disease progression and/or resistance may involve a reprogrammable signaling mainframe that elicits alternative growth and survival signals. This review attempts to meld current perceptions related to HER2-positive metastatic breast cancer with particular attention to current biological insights and therapeutic challenges.

Rational Design of Constrained Peptides as Protein Interface Inhibitors

The lack of progress in developing targeted therapeutics directed at protein–protein complexes has been due to the absence of well-defined ligand-binding pockets and the extensive intermolecular contacts at the protein–protein interface. Our laboratory has developed approaches to dissect protein–protein complexes focusing on the superfamilies of erbB and tumor necrosis factor (TNF) receptors by the combined use of structural biology and computational biology to facilitate small molecule development. We present a perspective on the development and application of peptide inhibitors as well as immunoadhesins to cell surface receptors performed in our laboratory.

Source and Impact of the EGF Family of Ligands on Intestinal Stem Cells

Epidermal Growth Factor (EGF) has long been known for its role in promoting proliferation of intestinal epithelial cells. EGF is produced by epithelial niche cells at the base of crypts in vivo and is routinely added to the culture medium to support the growth of intestinal organoids ex vivo. The recent identification of diverse stromal cell populations that reside underneath intestinal crypts has enabled the characterization of key growth factor cues supplied by these cells. The nature of these signals and how they are delivered to drive intestinal epithelial development, daily homeostasis and tissue regeneration following injury are being investigated. It is clear that aside from EGF, other ligands of the family, including Neuregulin 1 (NRG1), have distinct roles in supporting the function of intestinal stem cells through the ErbB pathway.

Second-line Afatinib or Chemotherapy Following Immunochemotherapy for the Treatment of Metastatic, Squamous Cell Carcinoma of the Lung: Real-world Effectiveness and Safety From a Multisite Retrospective Chart Review in the USA

BACKGROUND

The ErbB family blocker, afatinib, is approved for patients with squamous cell carcinoma (SqCC) of the lung following platinum-doublet chemotherapy but has not been explored following immunochemotherapy. Here, we assessed the characteristics and outcomes of patients with SqCC of the lung who received second-line afatinib or chemotherapy after first-line pembrolizumab plus chemotherapy in a "real-world" setting.

METHODS

In this retrospective, multisite cohort study, community oncologists identified eligible patients and extracted data from electronic health records. Primary outcome measures were patient demographics and clinical characteristics, time on treatment, and incidence of severe immune-related adverse events (irAEs).

RESULTS

Two hundred patients were included: 99 received second-line afatinib and 101 received second-line chemotherapy. Median age was 68 and 66 years, respectively; 35% and 3% of patients had mixed histology tumors, and 39% and 5% of tumors were epidermal growth factor receptor (EGFR) mutation-positive (EGFRm⁺). Median time on treatment was 7.3 months with afatinib (mixed histology/SqCC tumors: 8.1/5.8 months; EGFRm⁺/EGFRm^- tumors: 7.4/5.9 months) and 4.2 months with chemotherapy. Grade 3/4 irAEs were observed in 6 patients in the afatinib cohort (all had a prior grade 3/4 irAE during first-line therapy) and no patients in the chemotherapy cohort. The most common adverse drug reactions with afatinib were diarrhea (26%), rash (6%), stomatitis, fatigue, and nausea (5% each).

CONCLUSION

Encouraging time on treatment, and absence of newly diagnosed irAEs, indicate that afatinib is a treatment option following immunochemotherapy in patients with SqCC of the lung, and is currently the only approved oral agent in this setting.

NRG/ErbB signaling regulates neonatal muscle growth but not neuromuscular contractures in neonatal brachial plexus injury

Neonatal brachial plexus injury (NBPI) causes disabling and incurable muscle contractures that are driven by impaired growth of denervated muscles. A rare form of NBPI, which maintains afferent muscle innervation despite motor denervation, does not cause contractures. As afferent innervation regulates various aspects of skeletal muscle homeostasis through NRG/ErbB signaling, our current study investigated the role of this pathway in modulating contracture development. Through pharmacologic modification with an ErbB antagonist and NRG1 isoforms, we discovered that NRG/ErbB signaling does not modulate the development of contractures in neonatal mice. Instead, ErbB inhibition impeded growth in nondenervated skeletal muscles, whereas increased ErbB activation exacerbated denervation‐induced skeletal muscle atrophy. This potential regulatory effect of NRG/ErbB signaling on neonatal muscle growth warrants deeper investigation.

EGFR/ErbB2-Targeting Lapatinib Therapy for Aggressive Prolactinomas

CONTEXT

Approximately 10% to 20% of prolactinomas are resistant to dopamine agonist therapy. The ErbB signaling pathway may drive aggressive prolactinoma behavior.

OBJECTIVE

We evaluated lapatinib, an ErbB1-epidermal growth factor receptor (EGFR)/ErbB2 or human EGFR2 (HER2) tyrosine kinase inhibitor (TKI), in aggressive prolactinomas.

DESIGN

A prospective, phase 2a multicenter trial was conducted.

SETTING

This study took place at a tertiary referral pituitary center.

PATIENTS

Study participants included adults with aggressive prolactinomas showing continued tumor growth despite maximally tolerated dopamine agonist therapy.

INTERVENTION

Intervention included oral lapatinib 1250 mg/day for 6 months.

MAIN OUTCOME MEASURES

The primary end point was 40% reduction in any tumor dimension assessed by magnetic resonance imaging at study end; tumor response was assessed by Response Evaluation Criteria in Solid Tumors criteria. Secondary end points included prolactin (PRL) reduction, correlation of response with EGFR/HER2 expression, and safety.

RESULTS

Owing to rigorous inclusion criteria, of 24 planned participants, only 7 consented and 4 were treated. None achieved the primary end point but 3 showed stable disease, including 2 with a 6% increase and 1 with a 16.8% decrease in tumor diameter. PRL response was not always concordant with tumor response, as 2 showed 28% and 59% increases in PRL. The fourth participant had a PRL-secreting carcinoma and withdrew after 3 months of lapatinib because of imaging and PRL progression. EGFR/HER2 expression did not correlate with treatment response. Lapatinib was well tolerated overall, with reversible grade 1 transaminitis in 2 patients, grade 2 rash in 2 patients, and grade 1 asymptomatic bradycardia in 2 patients.

CONCLUSIONS

An oral TKI such as lapatinib may be an effective option for a difficult-to-treat patient with an aggressive prolactinoma.

LncRNA PCAT7 promotes the malignant progression of breast cancer by regulating ErbB/PI3K/Akt pathway

Aim: This study aimed to explore the mechanism of lncRNA PCAT7 underlying the progression of breast cancer, which will provide a basis for accurate diagnosis and targeted treatment. Methods: Data from The Cancer Genome Atlas data associated with breast cancer were used to identify the target lncRNA. In vitro experiments were conducted to detect gene expression and the effect of the lncRNA on cancer cell activities. Results: PCAT7 was found to be highly expressed in breast cancer tissue and cells, which activated the ErbB/PI3K/Akt pathway to potentiate cancer cell proliferation, migration and invasion and suppress apoptosis. Conclusion: PCAT7 is likely to promote tumor cell activities by activating ErbB/PI3K/Akt pathway, in turn potentiating tumor malignant progression.

m5C RNA Methylation Primarily Affects the ErbB and PI3K-Akt Signaling Pathways in Gastrointestinal Cancer

5-Methylcytosine (m⁵C) is a kind of methylation modification that occurs in both DNA and RNA and is present in the highly abundant tRNA and rRNA. It has an important impact on various human diseases including cancer. The function of m⁵C is modulated by regulatory proteins, including methyltransferases (writers) and special binding proteins (readers). This study aims at comprehensive study of the m⁵C RNA methylation-related genes and the main pathways under m⁵C RNA methylation in gastrointestinal (GI) cancer. Our result showed that the expression of m⁵C writers and reader was mostly up-regulated in GI cancer. The NSUN2 gene has the highest proportion of mutations found in GI cancer. Importantly, in liver cancer, higher expression of almost all m⁵C regulators was significantly associated with lower patient survival rate. In addition, the expression level of m⁵C-related genes is significantly different at various pathological stages. Finally, we have found through bioinformatics analysis that m⁵C regulatory proteins are closely related to the ErbB/PI3K–Akt signaling pathway and GSK3B was an important target for m⁵C regulators. Besides, the compound termed streptozotocin may be a key candidate drug targeting on GSK3B for molecular targeted therapy in GI cancer.

Targeting of HER/ErbB family proteins using broad spectrum Sec61 inhibitors coibamide A and apratoxin A

Coibamide A is a potent cancer cell toxin and one of a select group of natural products that inhibit protein entry into the secretory pathway via a direct inhibition of the Sec61 protein translocon. Many Sec61 client proteins are clinically relevant drug targets once trafficked to their final destination in or outside the cell, however the use of Sec61 inhibitors to block early biosynthesis of specific proteins is at a pre-clinical stage. In the present study we evaluated the action of coibamide A against human epidermal growth factor receptor (HER, ErbB) proteins in representative breast and lung cancer cell types. HERs were selected for this study as they represent a family of Sec61 clients that is frequently dysregulated in human cancers, including coibamide-sensitive cell types. Although coibamide A inhibits biogenesis of a broad range of Sec61 substrate proteins in a presumed substrate-nonselective manner, endogenous HER3 (ErbB-3) and EGFR (ErbB-1) proteins were more sensitive to coibamide A, and the related Sec61 inhibitor apratoxin A, than HER2 (ErbB-2). Despite this rank order of sensitivity (HER3 > EGFR > HER2), Sec61-dependent inhibition by coibamide A was sufficient to decrease cell surface expression of HER2. We report that coibamide A- or apratoxin A-mediated block of HER3 entry into the secretory pathway is unlikely to be mediated by the HER3 signal peptide alone. HER3 (G11L/S15L), that is fully resistant to the highly substrate-selective cotransin analogue CT8, was more resistant than wild-type HER3 but only at low coibamide A (3 nM) concentrations; HER3 (G11L/S15L) expression was inhibited by higher concentrations of either natural product. Time- and concentration-dependent decreases in HER protein expression induced a commensurate reduction in AKT/MAPK signaling in breast and lung cancer cell types and loss in cell viability. Coibamide A potentiated the cytotoxic efficacy of small molecule kinase inhibitors lapatinib and erlotinib in breast and lung cancer cell types, respectively. These data indicate that natural product modulators of Sec61 function have value as chemical probes to interrogate HER/ErbB signaling in treatment-resistant human cancers.

Afatinib is active in osteosarcoma in osteosarcoma cell lines

PURPOSE

Osteosarcoma is the most common bone tumor, mainly affecting adolescents and young adults, and metastatic disease has poor outcomes with a dismal overall survival. Currently, chemotherapy is the standard of care with limited results, finding that new therapies could improve these outcomes. Preclinical and clinical studies have suggested a possible important role of ErbB pathway aberrations in osteosarcoma etiology. The present study shows the effect of afatinib, an irreversible ErbB family blocker in osteosarcoma cell lines.

METHODS

Within a panel of human osteosarcoma cell lines, we addressed cell viability assay using afatinib at increasing concentrations. Motility was measured in wound-healing assays and invasion capacity was assessed in Transwell chamber assays. Finally, to monitor ErbB pathway modulation by afatinib and related compounds, we used Western blot analyses.

RESULTS

Cell viability inhibition, as well as a reduction of motility and migration of osteosarcoma cell line were observed after treatment with afatinib. Likewise, in the HOS cell line, afatinib decreased phosphorylation of key components in the ErbB signaling pathway.

CONCLUSIONS

Afatinib shows relevant antitumor effect in several osteosarcoma cell lines, as it causes a significant impact on cell viability, motility, and migration with a significant decrease in the activation of ErbB pathway activity.

Neuregulin-1 triggers GLUT4 translocation and enhances glucose uptake independently of insulin receptor substrate and ErbB3 in neonatal rat cardiomyocytes

During stress conditions such as pressure overload and acute ischemia, the myocardial endothelium releases neuregulin-1β (NRG-1), which acts as a cardioprotective factor and supports recovery of the heart. Recently, we demonstrated that recombinant human (rh)NRG-1 enhances glucose uptake in neonatal rat ventricular myocytes via the ErbB2/ErbB4 heterodimer and PI3Kα. The present study aimed to further elucidate the mechanism whereby rhNRG-1 activates glucose uptake in comparison to the well-established insulin and to extend the findings to adult models. Combinations of rhNRG-1 with increasing doses of insulin did not yield any additive effect on glucose uptake measured as ³H-deoxy-d-glucose incorporation, indicating that the mechanisms of the two stimuli are similar. In c-Myc-GLUT4-mCherry-transfected neonatal rat cardiomyocytes, rhNRG-1 increased sarcolemmal GLUT4 by 16-fold, similar to insulin. In contrast to insulin, rhNRG-1 did not phosphorylate IRS-1 at Tyr⁶¹², indicating that IRS-1 is not implicated in the signal transmission. Treatment of neonatal rats with rhNRG-1 induced a signaling response comparable with that observed in vitro, including increased ErbB4-pTyr¹²⁸⁴, Akt-pThr³⁰⁸ and Erk1/2-pThr²⁰²/Tyr²⁰⁴. In contrast, in adult cardiomyocytes rhNRG-1 only increased the phosphorylation of Erk1/2 without having any significant effect on Akt and AS160 phosphorylation and glucose uptake, suggesting that rhNRG-1 function in neonatal cardiomyocytes differs from that in adult cardiomyocytes. In conclusion, our results show that similar to insulin, rhNRG-1 can induce glucose uptake by activating the PI3Kα-Akt-AS160 pathway and GLUT4 translocation. Unlike insulin, the rhNRG-1-induced effect is not mediated by IRS proteins and is observed in neonatal, but not in adult rat cardiomyocytes.

Novel Pituitary Actions of Epidermal Growth Factor: Receptor Specificity and Signal Transduction for UTS1, EGR1, and MMP13 Regulation by EGF

Epidermal growth factor (EGF) is a member of the EGF-like ligands family, which plays a vital role in cell proliferation, differentiation, and folliculogenesis through binding with EGF receptors, including ErbB1 (EGFR/HER1), ErbB2 (HER2), ErbB3 (HER3), and ErbB4 (HER4). In mammals, many functional roles of EGF have been reported in the ovaries and breasts. However, little is known about the functions of EGF in the pituitary, especially in teleost. In this study, using grass carp pituitary cells as the model, we try to examine the direct pituitary actions of EGF in teleost. Firstly, transcriptomic analysis showed that 599 different expressed genes (DEGs) between the control and EGF-treatment group were mainly involved in cell proliferation, cell migration, signal transduction, and transcriptional regulation. Then, we further confirmed that EGF could significantly induce UTS1, EGR1, and MMP13 mRNA expression in a time-and dose-dependent manner. The stimulatory actions of EGF on UTS1 and EGR1 mRNA expression were mediated by the MEK_1/2/ERK_1/2 and PI₃K/AKT/mTOR pathways coupled with both ErbB1 and ErbB2 in grass carp pituitary cells. The receptor specificity and signal transductions for the corresponding responses on MMP13 mRNA expression were also similar, except that the ErbB2 and PI₃K/AKT/mTOR pathway were not involved. As we know, MMP13 could release EGF from HB-EGF. Interestingly, our data also showed that the MMPs inhibitor BB94 could suppress EGF-induced UTS1 and EGR1 mRNA expression. These results, taken together, suggest that the stimulatory actions of EGF on UTS1 and EGR1 mRNA expression could be enhanced by EGF-induced MMP13 expression in the pituitary.

HER3 and HER4 are highly expressed in human meningiomas

HER3 and HER4 are tyrosine kinase receptors of the ErbB family that have been detected in several cancers but lack substantial investigation in human meningiomas. In this study, HER3 and -4 expression levels were evaluated as potential biomarkers by immunohistochemistry and explored for association to clinical features in a large series of human meningiomas. 186 primary intracranial meningiomas from adult patients were investigated with antibodies against HER3 and -4 intracellular domains. Tumors were scored with a staining index (SI) based on cytoplasmic/membranous staining intensity and on the percentage of positive cells. SIs were tested for associations with WHO malignancy grade, tumor subtype, localization, and prognosis. HER3 and HER4 were highly expressed in most tumors. Both cytoplasmic and membranous immunoreactivity occurred, and for HER4 nuclear immunoreactivity was observed as well. Non-neoplastic meningeal tissue was not immunoreactive. HER3 and -4 immunoreactivity was not associated with WHO malignancy grade, nor with recurrence or survival in adjusted analyses. Meningiomas of all grades were shown to widely express both HER3 and HER4 receptors. This feature may have diagnostic value since non-neoplastic meninges were not immunoreactive. There was no prognostic significance in adjusted survival analyses.

Cripto-1 overexpression in U87 glioblastoma cells activates MAPK, focal adhesion and ErbB pathways

Discovering the underlying signalling pathways that control cancer cells is crucial for understanding their biology and to develop therapeutic regimens. Thus, the aim of the present study was to determine the effect of Cripto-1 on pathways controlling glioblastoma (GBM) cell function. To this end, changes in protein phosphorylation in cells overexpressing Cripto-1 were analysed using the Kyoto Encyclopedia of Genes and Genomes pathway analysis tool, as well as the Uniprot resource to identify the functions of Cripto-1-dependent phosphorylated proteins. This revealed that proteins affected by Cripto-1 overexpression are involved in multiple signalling pathways. The mitogen-activated protein kinase (MAPK), focal adhesion (FA) and ErbB pathways were found to be enriched by Cripto-1 overexpression with 35, 27 and 24% of pathway proteins phosphorylated, respectively. These pathways control important cellular processes in cancer cells that correlate with the observed functional changes described in earlier studies. More specifically, Cripto-1 may regulate MAPK cellular proliferation and survival pathways by activating epithelial growth factor receptor (EGFR; Ser1070) or fibroblast GFR1 (Tyr654). Its effect on cellular proliferation and survival could be mediated through Src (Tyr418), FA kinase (FAK; Tyr396), p130CAS (Tyr410), c-Jun (Ser63), Paxillin (PXN; Tyr118) and BCL2 (Thr69) of the FA pathway. Cripto-1 may also control cellular motility and invasion by activating Src (Tyr418), FAK (Tyr396) and PXN (Tyr118) of the FA pathway. However, Cripto-1 regulation of cellular invasion and migration might be not limited to the FA pathway, it may also control these cellular mechanisms through signalling via EGFR (Ser1070)/Her2 (Tyr877) to mediate the Src (Tyr418) and FAK (Tyr396) cascade activation of the ErbB signalling pathway. Angiogenesis could be mediated by Cripto-1 by activating c-Jun (Ser63) through EGFR (Ser1070)/Her2 (Tyr877) of the ErbB pathway. To conclude, the present study has augmented and enriched our current knowledge on the crucial roles that Cripto-1 may play in controlling different cellular mechanisms in GBM cells.

Development of treatment options for Chinese patients with advanced squamous cell lung cancer: focus on afatinib

Lung cancer is the leading cause of cancer death in China, and approximately one third of these cancers are squamous cell carcinoma (SqCC) of the lung. Ethnic diversity and country-specific environmental factors can account for interindividual variations in response to and tolerability of anticancer therapies. Although several targeted therapies have recently been approved for patients with relapsed/refractory SqCC of the lung, only afatinib, an irreversible ErbB family blocker, has data of Chinese patients. In the Phase III LUX-Lung 8 trial, afatinib demonstrated a significant clinical benefit vs the reversible first-generation EGFR tyrosine kinase inhibitor erlotinib in both the overall population and the Chinese subset, with a manageable safety profile. Emerging biomarker data from LUX-Lung 8 suggest that patients with ErbB mutations, especially ErbB2, and those classified as “good” in the VeriStrat^® proteomic test, may benefit from afatinib treatment in particular, regardless of ethnicity, and may get a long-term response. In conclusion, afatinib is a valid second-line option for Chinese patients with SqCC of the lung, and specific biomarkers may help guide in treatment decision-making. Ongoing studies will provide further guidance on afatinib’s place in the treatment algorithm, alongside the other novel targeted therapies.

A fungicide miconazole ameliorates tri-o-cresyl phosphate-induced demyelination through inhibition of ErbB/Akt pathway

Organophosphorus compound (OP)-induced delayed neuropathy (OPIDN) is characterized by distal axonal degeneration and demyelination of the central and peripheral axons, which leads to progressive muscle weakness, ataxia and paralysis in several days after OP intoxication. This study aimed to investigate the possible use of an imidazole fungicide miconazole as a novel therapy for OPIDN. Adult hens, the most commonly used animal models in OPIDN studies, were orally given tri-o-cresyl phosphate (TOCP). We showed that miconazole, which was administered daily to hens beginning on the 7th day after TOCP exposure, drastically ameliorated the neurotoxic symptoms and histopathological damages in spinal cord and sciatic nerves. Mechanistically, miconazole inhibited the TOCP-induced activation of ErbB/Akt signaling, and enhanced the myelin basic protein (MBP) expression. In a glial cell model sNF96.2 cells, miconazole restored the TOCP-inhibited MBP expression, and promoted cell differentiation as well as cell migration by inhibiting the activation of ErbB/Akt signaling pathway. In sum, miconazole, a synthetic imidazole fungicide, could ameliorate the symptoms and histopathological changes of OPIDN, probably by promoting glial cell differentiation and migration to enhance myelination via inhibiting the activation of ErbB/Akt. Thus, miconazole is a promising candidate therapy for the clinical treatment of OPIDN.

The Auricular VX2 Carcinoma Is a Suitable Animal Model for Identifying Biomarkers for HNSCC Therapy Response

BACKGROUND/AIM

The rabbit auricular VX2 carcinoma is an established animal model for human head and neck squamous cell carcinoma (HNSCC). Previously, we observed that intraperitoneal oxidative (O₃/O₂) stress induced tumor remission. Our aim was to evaluate candidate genes associated with tumor regression.

MATERIALS AND METHODS

For identification of tumor remission-related genes, microarray analysis was performed with subsequent validation by polymerase chain reaction (PCR), in situ hybridization, immunohistochemistry and western blot analysis.

RESULTS

Microarray analysis indicated a prominent reduction of epidermal growth factor receptor (Egfr, Erbb1) expression levels in regressing tumors. Quantitative PCR confirmed a significant (p<0.005) down-regulation of Erbb1-3 mRNA in regressing VX2 tumors. Histological localization of Erbb1-3 mRNA transcript and protein indicated reduced Erbb gene expression occurring at the level of individual VX2 tumor cells rather than solely being an effect of tumor shrinkage. This study highlights changes in the Erbb gene signature of regressing VX2 carcinomas as a predictor for therapy response. The VX2 carcinoma animal model, therefore, appears suitable for the identification and evaluation of new diagnostic, prognostic and therapeutic biomarkers prior to their application in patients with HNSCC.

Reduced expression of Nrdp1 predicts a poor prognosis in human hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is an aggressive form of liver cancer with particularly poor survival rates for patients. Targeted molecular therapies are lacking, and current treatment is generally limited to surgical resection or liver transplantation. Overexpression and aberrant signaling of the ErbB family of receptors has been implicated in HCC, but the mechanisms underlying ErbB overexpression are unclear. In this study, we investigated the potential role of neuregulin receptor degradation protein-1 (Nrdp1), a regulator of ErbB3 protein stability, in HCC progression.

Methods

We compared the expression of Nrdp1 in various HCC cell lines and in 8 pairs of tumor and peritumor tissue samples using Western blot analysis. Changes in the degree of proliferation were determined before and after small interfering RNA (siRNA)-induced knockdown of Nrdp1 using a cell counting Kit-8 (ccK-8) assay and cell-cycle analysis. The correlation between Nrdp1 expression and prognosis was determined in specimens of 89 HCC patients.

Results

Nrdp1 expression is significantly reduced in HCC tissues compared with adjacent healthy tissues. Higher Nrdp1 expression corresponds to lower maximal tumor size (χ², P<0.05), lower histological grade (χ², P<0.05), and higher survival rates by Kaplan–Meier estimate (P<0.05). Higher Nrdp1 expression also corresponds to reduced expression of Ki-67, a marker of cell proliferation (Spearman, r²=0.734; P<0.05). Nrdp1 accumulates in serum-starved HepG2 cancer cells and progressively decreases in expression after re-feeding. Furthermore, depletion of Nrdp1 in healthy L02 cells by siRNA results in enhanced cell proliferation and a greater proportion of cells in S phase.

Conclusions

Our findings suggest an inhibitory role for Nrdp1 in HCC tumorigenesis, and we propose that Nrdp1 may serve as a prognostic biomarker for HCC and as a potential therapeutic target for the treatment of HCC.

The S100A4 Protein Signals through the ErbB4 Receptor to Promote Neuronal Survival

Understanding the mechanisms of neurodegeneration is crucial for development of therapies to treat neurological disorders. S100 proteins are extensively expressed in the injured brain but S100's role and signalling in neural cells remain elusive. We recently demonstrated that the S100A4 protein protects neurons in brain injury and designed S100A4-derived peptides mimicking its beneficial effects. Here we show that neuroprotection by S100A4 involves the growth factor family receptor ErbB4 and its ligand Neuregulin 1 (NRG), key regulators of neuronal plasticity and implicated in multiple brain pathologies. The neuroprotective effect of S100A4 depends on ErbB4 expression and the ErbB4 signalling partners ErbB2/Akt, and is reduced by functional blockade of NRG/ErbB4 in cell models of neurodegeneration. We also detect binding of S100A4 with ErbB1 (EGFR) and ErbB3. S100A4-derived peptides interact with, and signal through ErbB, are neuroprotective in primary and immortalized dopaminergic neurons, and do not affect cell proliferation/motility - features which make them promising as potential neuroprotectants. Our data suggest that the S100-ErbB axis may be an important mechanism regulating neuronal survival and plasticity.

Activation of Neuregulin 1/ErbB Signaling Is Involved in the Development of TOCP-Induced Delayed Neuropathy

Organophosphate-induced delayed neuropathy (OPIDN) is characterized by progressive axonal degeneration and demyelination of the spinal cord and sciatic nerves. The neuregulin 1/epidermal growth factor receptor (ErbB) signaling pathway is crucial for axonal myelination. In this study, we investigated whether the neuregulin 1/ErbB signaling pathway mediated the progression of OPIDN. Adult hens were given tri-o-cresyl phosphate (TOCP), a typical neuropathic organophosphorus compound, to induce OPIDN. The ErbB inhibitor lapatinib was administered to hens 4 h prior to and 4 days after TOCP exposure. The neuregulin 1/ErbB signaling pathway was examined for their role in maintaining spinal cord and sciatic nerve fiber integrity. Schwann cell line sNF96.2 was used as the in vitro cell model. The in vivo results showed that TOCP (750 mg/kg body weight, p.o.) induced prominent ataxia and significant axon degeneration in the spinal cord and sciatic nerves. Lapatinib (25 mg/kg body weight, p.o.) treatment attenuated OPIDN clinically and histopathlogically and partially prevented the TOCP-induced activation of neuregulin 1/ErbB signaling pathway. Lapatinib also prevented the TOCP-induced inhibition of neuropathy target esterase (NTE), a key enzyme during the development of OPIDN, and the disturbed metabolism of phosphatidylcholine in sciatic nerves. In addition, lapatinib was shown, in vitro, to protect sNF96.2 cells from TOCP-induced dedifferentiation through neuregulin 1/ErbB signaling. Our results suggest that neuregulin 1/ErbB, through regulation of NTE activity in the peripheral nervous system, mediates the progression of OPIDN. Thus, this signal may serve as a potential target for the treatment of OPIDN.

EGFR-TKIs resistance via EGFR-independent signaling pathways

Tyrosine kinase inhibitors (TKIs)-treatments bring significant benefit for patients harboring epidermal growth factor receptor (EGFR) mutations, especially for those with lung cancer. Unfortunately, the majority of these patients ultimately develop to the acquired resistance after a period of treatment. Two central mechanisms are involved in the resistant process: EGFR secondary mutations and bypass signaling activations. In an EGFR-dependent manner, acquired mutations, such as T790 M, interferes the interaction between TKIs and the kinase domain of EGFR. While in an EGFR-independent manner, dysregulation of other receptor tyrosine kinases (RTKs) or abnormal activation of downstream compounds both have compensatory functions against the inhibition of EGFR through triggering phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinase (MAPK) signaling axes. Nowadays, many clinical trials aiming to overcome and prevent TKIs resistance in various cancers are ongoing or completed. EGFR-TKIs in accompany with the targeted agents for resistance-related factors afford a promising first-line strategy to further clinical application.

Soluble Neuregulin1 is strongly up-regulated in the rat model of Charcot-Marie-Tooth 1A disease

Neuregulin1 (NRG1) is a growth factor playing a pivotal role in peripheral nerve development through the activation of the transmembrane co-receptors ErbB2-ErbB3. Soluble NRG1 isoforms, mainly secreted by Schwann cells, are strongly and transiently up-regulated after acute peripheral nerve injury, thus suggesting that they play a crucial role also in the response to nerve damage. Here we show that in the rat experimental model of the peripheral demyelinating neuropathy Charcot-Marie-Tooth 1A (CMT1A) the expression of the different NRG1 isoforms (soluble, type α and β, type a and b) is strongly up-regulated, as well as the expression of NRG1 co-receptors ErbB2-ErbB3, thus showing that CMT1A nerves have a gene expression pattern highly reminiscent of injured nerves. Because it has been shown that high concentrations of soluble NRG1 negatively affect myelination, we suggest that soluble NRG1 over-expression might play a negative role in the pathogenesis of CMT1A disease, and that a therapeutic approach, aimed to interfere with NRG1 activity, might be beneficial for CMT1A patients. Further studies will be necessary to test this hypothesis in animal models and to evaluate NRG1 expression in human patients. Impact statement Charcot-Marie-Tooth1A (CMT1A) is one of the most frequent inherited neurological diseases, characterized by chronic demyelination of peripheral nerves, for which effective therapies are not yet available. It has been recently proposed that the treatment with soluble Neuregulin1 (NRG1), a growth factor released by Schwann cells immediately after acute nerve injury, might be effective in CMT1A treatment. However, the expression of the different isoforms of endogenous NRG1 in CMT1A nerves has not been yet investigated. In this preliminary study, we demonstrate that different isoforms of soluble NRG1 are strongly over-expressed in CMT1A nerves, thus suggesting that a therapeutic approach based on NRG1 treatment should be carefully reconsidered. If soluble NRG1 is over-expressed also in human CMT1A nerves, a therapeutic approach aimed to inhibit (instead of stimulate) the signal transduction pathways driven by NRG1 might be fruitfully developed. Further studies will be necessary to test these hypotheses.

[Afatinib in patients with squamous cell carcinoma of the lung: current context and the option of oral treatment]

Squamous cell carcinoma (SCC) of the lung represents 30% of non-small cell lung cancers (NSCLC). Docetaxel and the EGFR tyrosine kinase inhibitor (TKI), erlotinib, are the only two drugs approved for second-line treatment of advanced SCC. The sensitivity of SCC to TKIs can be explained by EGFR overexpression. Erlotinib demonstrated a significant benefit in terms of overall survival (OS) in successive lines in NSCLC, including squamous histology. The magnitude of this benefit is similar to that of chemotherapy. Afatinib is an irreversible inhibitor of the entire ErbB family (EGFR, HER2-4) that has recently been approved for its current indication, advanced EGFR mutation-positive NSCLC and has well-defined and manageable toxicity, mainly gastrointestinal and cutaneous. The LUX-Lung 8 study was a phase III randomized trial in patients with NSCLC with squamous histology that compared erlotinib versus afatinib as second-line treatment. A total of 795 patients were included and a significant benefit was observed for afatinib in progression-free survival (2.7 vs 1.9 months (HR 0.79 [95%CI 0.68-0.91]; p=0.0012) and in OS (7.9 vs 6.8 months (HR 0.81 [95%CI 0.69-0.95]; p=0.0077), as well as a significant improvement in OS at 12 and 18 months. More diarrhoea and stomatitis was observed with afatinib and more rash with erlotinib, but the overall proportion of toxicity was similar in each group. Afatinib offered better results in quality of life. In summary, afatinib is a second-line treatment option in squamous NSCLC based on its survival advantage over erlotinib.

Neuregulin and Dopamine D4 Receptors Contribute Independently to Depotentiation of Schaffer Collateral LTP by Temperoammonic Path Stimulation

Prior studies have found that dopamine (DA), acting at D4 receptors, and neuregulin (NRG), likely acting at ErbB4 receptors, are involved in a form of depotentiation of long-term potentiation (LTP) at Schaffer collateral (SC) synapses in the hippocampus. Furthermore, DA and NRG actions are intertwined in that NRG induces DA release. We previously found that low-frequency stimulation (LFS) of temperoammonic (TA) inputs to area CA1 also depotentiates previously established SC LTP through a complex signaling pathway involving endocannabinoids, GABA, adenosine, and mitogen-activated protein kinases (MAPKs), but not glutamate. In the present studies, we found that TA-induced SC depotentiation in hippocampal slices from Sprague-Dawley albino rats also involves activation of both D4 receptors and NRG-activated ErbB receptors, but that the roles of these two modulator systems are independent with D4 receptor antagonism failing to alter chemical depotentiation by NRG1β. Furthermore, a selective D4 receptor agonist was unable to depotentiate SC LTP when administered alone, suggesting that D4 receptor activation is necessary but not sufficient for TA-induced SC depotentiation. Chemical depotentiation by NRG1β was inhibited by a Pan-ErbB antagonist and by picrotoxin (PTX), an antagonist of GABA-A receptors (GABA_ARs), indicating that NRG likely promotes SC depotentiation via effects on GABA and interneurons. These findings have implications for understanding the role of DA and NRG in cognitive dysfunction associated with neuropsychiatric illnesses.