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.