Heregulin-induced activation of ErbB3 by EGFR tyrosine kinase activity promotes tumor growth and metastasis in melanoma cells

Analysis on the pathogenesis and treatment progress of NRG1 fusion-positive non-small cell lung cancer

Lung cancer persistently leads as the primary cause of morbidity and mortality among malignancies. A notable increase in the prevalence of lung adenocarcinoma has become evident in recent years. Although targeted therapies have shown in treating certain subsets of non-small cell lung cancers (NSCLC), a significant proportion of patients still face suboptimal therapeutic outcomes. Neuregulin-1 (NRG1), a critical member of the NRG gene family, initially drew interest due to its distribution within the nascent ventricular endocardium, showcasing an exclusive presence in the endocardium and myocardial microvessels. Recent research has highlighted NRG1's pivotal role in the genesis and progression across a spectrum of tumors, influencing molecular perturbations across various tumor-associated signaling pathways. This review provides a concise overview of NRG1, including its expression patterns, configuration, and fusion partners. Additionally, we explore the unique features and potential therapeutic strategies for NRG1 fusion-positive occurrences within the context of NSCLC.

HER3-targeted therapy: the mechanism of drug resistance and the development of anticancer drugs

Human epidermal growth factor receptor 3 (HER3), which is part of the HER family, is aberrantly expressed in various human cancers. Since HER3 only has weak tyrosine kinase activity, when HER3 ligand neuregulin 1 (NRG1) or neuregulin 2 (NRG2) appears, activated HER3 contributes to cancer development and drug resistance by forming heterodimers with other receptors, mainly including epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2). Inhibition of HER3 and its downstream signaling, including PI3K/AKT, MEK/MAPK, JAK/STAT, and Src kinase, is believed to be necessary to conquer drug resistance and improve treatment efficiency. Until now, despite multiple anti-HER3 antibodies undergoing preclinical and clinical studies, none of the HER3-targeted therapies are licensed for utilization in clinical cancer treatment because of their safety and efficacy. Therefore, the development of HER3-targeted drugs possessing safety, tolerability, and sensitivity is crucial for clinical cancer treatment. This review summarizes the progress of the mechanism of HER3 in drug resistance, the HER3-targeted therapies that are conducted in preclinical and clinical trials, and some emerging molecules that could be used as future designed drugs for HER3, aiming to provide insights for future research and development of anticancer drugs targeting HER3.

Conformational diversity and protein-protein interfaces in drug repurposing in Ras signaling pathway

We focus on drug repurposing in the Ras signaling pathway, considering structural similarities of protein-protein interfaces. The interfaces formed by physically interacting proteins are found from PDB if available and via PRISM (PRotein Interaction by Structural Matching) otherwise. The structural coverage of these interactions has been increased from 21 to 92% using PRISM. Multiple conformations of each protein are used to include protein dynamics and diversity. Next, we find FDA-approved drugs bound to structurally similar protein-protein interfaces. The results suggest that HIV protease inhibitors tipranavir, indinavir, and saquinavir may bind to EGFR and ERBB3/HER3 interface. Tipranavir and indinavir may also bind to EGFR and ERBB2/HER2 interface. Additionally, a drug used in Alzheimer's disease can bind to RAF1 and BRAF interface. Hence, we propose a methodology to find drugs to be potentially used for cancer using a dataset of structurally similar protein-protein interface clusters rather than pockets in a systematic way.

Therapeutic targeting of anoikis resistance in cutaneous melanoma metastasis

The acquisition of resistance to anoikis, the cell death induced by loss of adhesion to the extracellular matrix, is an absolute requirement for the survival of disseminating and circulating tumour cells (CTCs), and for the seeding of metastatic lesions. In melanoma, a range of intracellular signalling cascades have been identified as potential drivers of anoikis resistance, however a full understanding of the process is yet to be attained. Mechanisms of anoikis resistance pose an attractive target for the therapeutic treatment of disseminating and circulating melanoma cells. This review explores the range of small molecule, peptide and antibody inhibitors targeting molecules involved in anoikis resistance in melanoma, and may be repurposed to prevent metastatic melanoma prior to its initiation, potentially improving the prognosis for patients.

Collectin-11 promotes cancer cell proliferation and tumor growth

Collectin-11 (CL-11) is a recently described soluble C-type lectin that has distinct roles in embryonic development, host defence, autoimmunity, and fibrosis. Here we report that CL-11 also plays an important role in cancer cell proliferation and tumor growth. Melanoma growth was found to be suppressed in Colec11-/- mice in a s.c. B16 melanoma model. Cellular and molecular analyses revealed that CL-11 is essential for melanoma cell proliferation, angiogenesis, establishment of more immunosuppressive tumor microenvironment, and the reprogramming of macrophages to M2 phenotype within melanomas. In vitro analysis revealed that CL-11 can activate tyrosine kinase receptors (EGFR, HER3) and ERK, JNK, and AKT signaling pathways and has a direct stimulatory effect on murine melanoma cell proliferation. Furthermore, blockade of CL-11 (treatment with L-fucose) inhibited melanoma growth in mice. Analysis of open data sets revealed that COLEC11 gene expression is upregulated in human melanomas and that high COLEC11 expression has a trend toward poor survival. CL-11 also had direct stimulatory effects on human tumor cell proliferation in melanoma and several other types of cancer cells in vitro. Overall, our findings provide the first evidence to our knowledge that CL-11 is a key tumor growth-promoting protein and a promising therapeutic target in tumor growth.

Mouse Syngeneic Melanoma Model with Human Epidermal Growth Factor Receptor Expression

The development of epidermal growth factor receptor (EGFR)-targeting agents for the treatment of malignant melanoma requires cheap and easy animal tumor models for high-throughput in vivo screening. Thus, the aim of this study was to develop mouse syngeneic melanoma model that expresses human EGFR. Cloudman S91 clone M3 mouse melanoma cells were transduced with lentiviral particles carrying the human EGFR gene followed by a multistep selection process. The resulting M3-EGFR has been tested for EGFR expression and functionality in vitro and in vivo. Radioligand assay confirmed the presence of 13,900 ± 1500 EGF binding sites per cell at a dissociation constant of 5.3 ± 1.4 nM. M3-EGFR demonstrated the ability to bind and internalize specifically and provide the anticipated intracellular nuclear import of three different EGFR-targeted modular nanotransporters designed for specific anti-cancer drug delivery. Introduction of the human EGFR gene did not alter the tumorigenicity of the offspring M3-EGFR cells in host immunocompetent DBA/2J mice. Preservation of the expression of EGFR in vivo was confirmed by immunohistochemistry. To sum up, we successfully developed the first mouse syngeneic melanoma model with preserved in vivo expression of human EGFR.

Targeting EGFR in melanoma - The sea of possibilities to overcome drug resistance

Melanoma is considered one of the most aggressive skin cancers. It spreads and metastasizes quickly and is intrinsically resistant to most conventional chemotherapeutics, thereby presenting a challenge to researchers and clinicians searching for effective therapeutic strategies to treat patients with melanoma. The use of inhibitors of mutated serine/threonine-protein kinase B-RAF (BRAF), e.g., vemurafenib and dabrafenib, has revolutionized melanoma chemotherapy. Unfortunately, the response to these drugs lasts a limited time due to the development of acquired resistance. One of the proteins responsible for this process is epidermal growth factor receptor (EGFR). In this review, we summarize the role of EGFR signaling in the multidrug resistance of melanomas and discuss possible applications of EGFR inhibitors to overcome the development of drug resistance in melanoma cells during therapy.

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.

A metabolic data-driven systems pharmacology strategy for decoding and validating the mechanism of Compound Kushen Injection against HCC

ETHNOPHARMACOLOGICAL RELEVANCE

Compound Kushen Injection (CKI) is a widely used TCM formula for treatment of carcinomatous pain and tumors of digestive system including hepatocellular carcinoma (HCC). However, the potential mechanisms of CKI for treatment of HCC have not been systematically and deeply studied.

AIM OF STUDY

A metabolic data-driven systems pharmacology approach was utilized to investigate the potential mechanisms of CKI for treatment of HCC.

MATERIALS AND METHODS

Based on phenotypic data generated by metabolomics and genotypic data of drug targets, a propagation model based on Dijkstra program was proposed to decode the effective network of key genotype-phenotype of CKI in treating HCC. The pivotal pathway was predicted by target propagation mode of our proposed model, and was validated in SMMC-7721 cells and diethylnitrosamine-induced rats.

RESULTS

Metabolomics results indicated that 12 differential metabolites, and 5 metabolic pathways might be involved in the anti-HCC effect of CKI. A total of 86 metabolic related genes that affected by CKI were obtained. The results calculated by propagation model showed that 6475 shortest distance chains might be involved in the anti-HCC effect of CKI. According to the results of propagation mode, EGFR was identified as the core target of CKI for the anti-HCC effect. Finally, EGFR and its related pathway EGFR-STAT3 signaling pathway were validated in vivo and in vitro.

CONCLUSION

The proposed method provides a methodological reference for explaining the underlying mechanism of TCM in treating HCC.

Xmrks the Spot: Fish Models for Investigating Epidermal Growth Factor Receptor Signaling in Cancer Research

Studies conducted in several fish species, e.g., Xiphophorus hellerii (green swordtail) and Xiphophorus maculatus (southern platyfish) crosses, Oryzias latipes (medaka), and Danio rerio (zebrafish), have identified an oncogenic role for the receptor tyrosine kinase, Xmrk, a gene product closely related to the human epidermal growth factor receptor (EGFR), which is associated with a wide variety of pathological conditions, including cancer. Comparative analyses of Xmrk and EGFR signal transduction in melanoma have shown that both utilize STAT5 signaling to regulate apoptosis and cell proliferation, PI3K to modulate apoptosis, FAK to control migration, and the Ras/Raf/MEK/MAPK pathway to regulate cell survival, proliferation, and differentiation. Further, Xmrk and EGFR may also modulate similar chemokine, extracellular matrix, oxidative stress, and microRNA signaling pathways in melanoma. In hepatocellular carcinoma (HCC), Xmrk and EGFR signaling utilize STAT5 to regulate cell proliferation, and Xmrk may signal through PI3K and FasR to modulate apoptosis. At the same time, both activate the Ras/Raf/MEK/MAPK pathway to regulate cell proliferation and E-cadherin signaling. Xmrk models of melanoma have shown that inhibitors of PI3K and MEK have an anti-cancer effect, and in HCC, that the steroidal drug, adrenosterone, can prevent metastasis and recover E-cadherin expression, suggesting that fish Xmrk models can exploit similarities with EGFR signal transduction to identify and study new chemotherapeutic drugs.

ERBB1/2/3 Expression, Prognosis, and Immune Infiltration in Cutaneous Melanoma

Background

The four ERBB tyrosine kinase family members [ERBB1 (epidermal growth factor receptor, EGFR), ERBB2 (HER2), ERBB3 (HER3), and ERBB4 (HER4)] (ERBB receptor family) have been shown, according to previous studies, to be related to the cutaneous melanoma. ERBB3 is the only member of the ERBBs that lacks tyrosine kinase activity and thus needs to dimer with other tyrosine kinases receptors to trigger the signaling pathway, while ERBB3 may dimer with all members of the ERBB family. Melanoma progression depends on activation of ERBB signaling, especially the ERBB3/ERBB2 cascade. There are lymphocytes and T cell infiltrates in melanoma. Numerous pieces of evidences indicate that local immune status plays an important role in the formation of anti-tumor immune responses. However, the relationship between the ERBBs and prognosis and immune infiltration in cutaneous melanoma is not completely clear.

Methods

The expression of the ERBBs was analyzed through the Oncomine database, Gene Expression Profiling Interactive Analysis (GEPIA), respectively. Immunohistochemistry of ERBBs was obtained from the Human Protein Atlas is increased before HPA database. ERBBs genes expression and mutation analysis in cutaneous melanoma from the cBioPortal. Functional annotation and Kyoto Encyclopedia of Genes and Genomes is increased before KEGG pathway enrichment analysis from the Metascape. Correlations between ERBBs and 31 genes that were close to each other and frequently altered were explored by GEPIA. Using the GEPIA database, we also investigated the relationship between ERBBs and myeloid-derived suppressor cells (MDSC) in cutaneous melanoma. The disease-free survival and different tumor stages of ERBBs were evaluated by GEPIA. The correlation of ERBBs and tumor-infiltrating immune cells and prognostic(5 years survival rates) was tested by the Tumor Immune Estimation Resource (TIMER).

Results

In general, the expression levels of ERBB1/2 in cutaneous melanoma were lower than those in normal skin tissue. By contrast, the ERBB3 expression level was higher in cutaneous melanoma than in normal skin tissue. Low expression of ERBB1/2 and high expression of ERBB3 were detrimental to the 5 years survival of cutaneous melanoma patients (ERBB1: log-rank P: 0.03; ERBB2: log-rank P: 0.008; ERBB3: log-rank P: 0.039). ERBB4 expression may not affect the prognosis of patients with cutaneous melanoma. ERBBs may not play a role in the tumor stage and disease-free survival in cutaneous melanoma patients. The relationship between the ERBB family and 31 genes that were close to each other and frequently altered is demonstrated as the genes regulated by the ERBB family being mainly concentrated in the RAS/RAF/MEK/ERK signaling pathway. ERBB2 can induce infiltration of CD8⁺ T cells and B cells, while ERBB3 can induce infiltration of CD4⁺ T cells, CD8⁺ T cells, and Neutrophil cells. ERBBs are more significantly associated with M1 macrophages, dendritic cells, Th1, Th2, Th17, and Treg cellular immune markers (Cor > 0.2). ERBB2/3 were related to MDSC in cutaneous melanoma, including human mononuclear myeloid-derived suppressor cells (M-MDSC) and polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC), and may influence the progression of cutaneous melanoma through MDSC, but the conclusion needs further probing.

Conclusion

This study investigated the prognosis and immune infiltration of the ERBB family in cutaneous melanoma. Our results suggest that ERBB1/2/3 may serve as early prognostic markers and potential therapeutic targets in cutaneous melanoma.

New insights into ErbB3 function and therapeutic targeting in cancer

INTRODUCTION

The importance of ErbB3 receptor tyrosine kinase in cancer progression, primary and acquired drug resistance, has become steadily evident since its discovery in 1989. ErbB3 overexpression in various solid organ malignancies is associated with shorter survival of patients. However, initial strategies to therapeutically target ErbB3 have not been rewarding.

AREAS COVERED

Here, we provide an overview of ErbB3 biology in carcinogenesis. We outline the role of ErbB3 as a critical pathway for resistance to other anti-cancer drugs. We focus on emerging clinical data, which will steer the potential future development of ErbB3 directed therapies.

EXPERT OPINION

Initial approaches to ErbB3 targeting have been challenging. However, the lack of success of anti-ErbB3 therapies in ongoing clinical trials may relate more to the complex biology of the receptor and challenges with the biomarkers used to date. Furthermore, it seems certain that the expression of the receptor per se is necessary but not sufficient for the response to ErbB3 therapies. Emerging data suggest that more sophisticated biomarkers are needed. Nonetheless, it is also likely that ErbB3 therapies may have the most efficacy in combination therapy, and their favorable toxicity profile makes this feasible.

TRPML1 Promotes Protein Homeostasis in Melanoma Cells by Negatively Regulating MAPK and mTORC1 Signaling

We screen ion channels and transporters throughout the genome to identify those required by human melanoma cells but not by normal human melanocytes. We discover that Mucolipin-1 (MCOLN1), which encodes the lysosomal cation channel TRPML1, is preferentially required for the survival and proliferation of melanoma cells. Loss of MCOLN1/TRPML1 function impairs the growth of patient-derived melanomas in culture and in xenografts but does not affect the growth of human melanocytes. TRPML1 expression and macropinocytosis are elevated in melanoma cells relative to melanocytes. TRPML1 is required in melanoma cells to negatively regulate MAPK pathway and mTORC1 signaling. TRPML1-deficient melanoma cells exhibit decreased survival, proliferation, tumor growth, and macropinocytosis, as well as serine depletion and proteotoxic stress. All of these phenotypes are partially or completely rescued by mTORC1 inhibition. Melanoma cells thus increase TRPML1 expression relative to melanocytes to attenuate MAPK and mTORC1 signaling, to sustain macropinocytosis, and to avoid proteotoxic stress.

Drug resistance of BRAF-mutant melanoma: Review of up-to-date mechanisms of action and promising targeted agents

Melanoma onset and progression are associated with a high variety of activating mutations in the MAPK-pathway, most frequently involving BRAF (35-45%) and NRAS (15-25%) genes, but also c-KIT and PTEN. Targeted therapies with BRAF and MEK inhibitors showed promising results over the past years, but it is known that most responses are temporary, and almost all of patients develop a tumor relapse within one year. Different drug-resistance mechanisms underlie the progression of disease and activation of both MAPK and PI3K/AKT/mTOR pathways. Therefore, in this article we reviewed the main studies about clinical effects of several target inhibitors, describing properly the most prominent mechanisms of both intrinsic and acquired resistance. Furthermore, suggestive strategies for overcoming drug resistance and the most recent alternative combination therapies to optimize the use of MAPK pathway inhibitors were also discussed.

Herbacetin suppressed MMP9 mediated angiogenesis of malignant melanoma through blocking EGFR-ERK/AKT signaling pathway

Malignant melanoma remains a challenge for clinical practice and novel therapeutic strategies are urgently needed. Herbacetin, a natural flavonoid compound that has multiple pharmacological activities, exerts anticancer effects on several human tumors. In this study, the anti-angiogenesis effect of Herbacetin in human malignant melanoma was investigated. The results indicated that Herbacetin treatment significantly suppressed tumor growth and angiogenesis of malignant melanoma both in vitro and in vivo. In melanoma A375 and Hs294T cells, Herbacetin treatment suppressed both EGF-induced and constitutive phosphorylation of EGFR, accelerated the internalization and degradation of EGFR, and subsequently suppressed the activation of the downstream kinases (AKT and ERK). Moreover, MMP9 was determined as a key angiogenic factor in Herbacetin treated melanoma cells. Knockdown of MMP9 suppressed the in vitro angiogenesis while overexpression of MMP9 in Herbacetin treated melanoma cells restored the angiogenesis ability. We concluded that Herbacetin suppressed melanoma angiogenesis through blocking EGFR-ERK/AKT-MMP9 signaling pathway and Herbacetin may be developed as a potential drug for melanoma treatment.

Functional interplay between secreted ligands and receptors in melanoma

Melanoma, the most aggressive form of skin cancer, results from the malignant transformation of melanocytes located in the basement membrane separating the epidermal and dermal skin compartments. Cutaneous melanoma is often initiated by solar ultraviolet radiation (UVR)-induced mutations. Melanocytes intimately interact with keratinocytes, which provide growth factors and melanocortin peptides acting as paracrine regulators of proliferation and differentiation. Keratinocyte-derived melanocortins activate melanocortin-1 receptor (MC1R) to protect melanocytes from the carcinogenic effect of UVR. Accordingly, MC1R is a major determinant of susceptibility to melanoma. Despite extensive phenotypic heterogeneity and high mutation loads, the molecular basis of melanomagenesis and the molecules mediating the crosstalk between melanoma and stromal cells are relatively well understood. Mutations of intracellular effectors of receptor tyrosine kinase (RTK) signalling, notably NRAS and BRAF, are major driver events more frequent than mutations in RTKs. Nevertheless, melanomas often display aberrant signalling from RTKs such as KIT, ERRB1-4, FGFR, MET and PDGFR, which contribute to disease progression and resistance to targeted therapies. Progress has also been made to unravel the role of the tumour secretome in preparing the metastatic niche. However, key aspects of the melanoma-stroma interplay, such as the molecular determinants of dormancy, remain poorly understood.

Positive prognostic value of HER2-HER3 co-expression and p-mTOR in gastric cancer patients

Background

The HER2-HER3 heterodimer significantly decreases survival in breast cancer patients. However, the prognostic value of HER2-HER3 overexpression remains unknown in gastric cancer (GC).

Methods

The expression levels of HER2, HER3, Akt, p-Akt, mTOR and p-mTOR were examined in specimens from 120 GC patients by immunohistochemistry and quantitative reverse transcription-PCR. The associations of HER proteins, PI3K/Akt/mTOR pathway-related proteins, clinicopathological features of GC, and overall survival (OS) were assessed. To comprehensively evaluate the prognostic values of pathway-related proteins, meta-analyses were conducted with STATA 11.0.

Results

HER2 overexpression was significantly associated with HER3 levels (P = 0.02). HER3 was highly expressed in gastric cancer tissues. High HER2 and HER3 levels were associated with elevated p-Akt and p-mTOR amounts (P < 0.05). Furthermore, HER2-HER3 co-expression was associated with high p-Akt and p-mTOR (P < 0.05) levels. Meanwhile, p-mTOR overexpression was tightly associated with differentiation, depth of invasion, lymph node metastasis, TNM stage and OS (P < 0.05). By meta-analyses, Akt, p-Akt, and mTOR levels were unrelated to clinicopathological characters. HER3 overexpression was associated with depth of invasion (OR = 2.39, 95%CI 1.62–3.54, P < 0.001) and lymph node metastasis (OR = 2.35, 95%CI 1.34–4.11, P = 0.003). Further, p-mTOR overexpression was associated with patient age, tumor location, depth of invasion (OR = 1.63, 95%CI 1.08–2.45, P = 0.02) and TNM stage (OR = 1.73, 95%CI 1.29–2.32, P < 0.001). In addition, HER2-HER3 overexpression corresponded to gradually shortened 5-year OS (P < 0.05), and significant relationships were shown among HER3, p-mTOR overexpression, and 1-, 3-, 5-year OS (P < 0.05).

Conclusions

HER2-HER3 co-expression may potentially enhance mTOR phosphorylation. HER2-HER3 co-expression and p-mTOR are both related to the prognosis of GC patients.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3851-y) contains supplementary material, which is available to authorized users.

Crosstalk signaling in targeted melanoma therapy

Inhibition of the BRAF/MAPK pathway belongs to the standard therapies for patients with activating BRAF^V600E/K mutations. However, even in well-responding tumors, anti-tumorigenic effect and clinical benefit are only transient, and the original tumors often relapse. This demonstrates that there are remaining residual tumors, which have withstood therapy-induced apoptosis and which have the potential to resume growth. Although BRAF mutant melanoma cells seem to depend on BRAF/MAPK signaling, the inhibition of this pathway triggers several events, which modulate the tumor as well as the tumor niche. After a certain adaptation period, this can turn out to be beneficial for tumor growth and metastasis-even in cases of good initial tumor response. This review sheds light on the biology of BRAF/MEK inhibitor-sensitive melanoma cells, which survive targeted therapy and will address the crosstalk signaling events occurring in BRAF mutant melanomas when the BRAF/MAPK pathway is fully blocked. The knowledge of these events is important for potential future drug combinations, which enhance the inhibitory effect of BRAF/MEK inhibition, particularly in patients not eligible for immune therapy.

TRPM5 mediates acidic extracellular pH signaling and TRPM5 inhibition reduces spontaneous metastasis in mouse B16-BL6 melanoma cells

Extracellular acidity is a hallmark of solid tumors and is associated with metastasis in the tumor microenvironment. Acidic extracellular pH (pH e ) has been found to increase intracellular Ca2+ and matrix metalloproteinase-9 (MMP-9) expression by activating NF-κB in the mouse B16 melanoma model. The present study assessed whether TRPM5, an intracellular Ca2+-dependent monovalent cation channel, is associated with acidic pH e signaling and induction of MMP-9 expression in this mouse melanoma model. Treatment of B16 cells with Trpm5 siRNA reduced acidic pH e -induced MMP-9 expression. Enforced expression of Trpm5 increased the rate of acidic pH e -induced MMP-9 expression, as well as increasing experimental lung metastasis. This genetic manipulation did not alter the pH e critical for MMP-9 induction but simply amplified the percentage of inducible MMP-9 at each pH e . Treatment of tumor bearing mice with triphenylphosphine oxide (TPPO), an inhibitor of TRPM5, significantly reduced spontaneous lung metastasis. In silico analysis of clinical samples showed that high TRPM5 mRNA expression correlated with poor overall survival rate in patients with melanoma and gastric cancer but not in patients with cancers of the ovary, lung, breast, and rectum. These results showed that TRPM5 amplifies acidic pH e signaling and may be a promising target for preventing metastasis of some types of tumor.

Long non-coding RNA CCAT1 promotes metastasis and poor prognosis in epithelial ovarian cancer

In this study, we reported that long non-coding RNA (lncRNA) CCAT1 was upregulated in epithelial ovarian cancer (EOC) tissues, and was associated with FIGO stage, histological grade, lymph node metastasis and poor survival of EOC patients. Multivariate Cox regression analysis showed that CCAT1 was an independent prognostic indicator. While CCAT1 downregulation inhibited EOC cell epithelial-mesenchymal transition (EMT), migration and invasion, CCAT1 upregulation promoted EOC cell EMT, migration and invasion. We further identified and confirmed that miR-152 and miR-130b were the targets of CCAT1, and CCAT1 functioned by targeting miR-152 and miR-130b. Subsequently, ADAM17 and WNT1, and STAT3 and ZEB1 were confirmed to be the targets of miR-152 and miR-130b, respectively, and could be regulated by CCAT1 in EOC cells. Knockdown of anyone of these four proteins inhibited EOC cell EMT, migration and invasion. Taken together, our study first revealed a critical role of CCAT1-miR-152/miR-130b-ADAM17/WNT1/STAT3/ZEB1 regulatory network in EOC cell metastasis. These findings provide great insights into EOC initiation and progression, and novel potential therapeutic targets and biomarkers for diagnosis and prognosis for EOC.

EGF and NRG induce phosphorylation of HER3/ERBB3 by EGFR using distinct oligomeric mechanisms

Heteromeric interactions between the catalytically impaired human epidermal growth factor receptor (HER3/ERBB3) and its catalytically active homologs EGFR and HER2 are essential for their signaling. Different ligands can activate these receptor pairs but lead to divergent signaling outcomes through mechanisms that remain largely unknown. We used stochastic optical reconstruction microscopy (STORM) with pair-correlation analysis to show that EGF and neuregulin (NRG) can induce different extents of HER3 clustering that are dependent on the nature of the coexpressed HER receptor. We found that the presence of these clusters correlated with distinct patterns and mechanisms of receptor phosphorylation. NRG induction of HER3 phosphorylation depended on the formation of the asymmetric kinase dimer with EGFR in the absence of detectable higher-order oligomers. Upon EGF stimulation, HER3 paralleled previously observed EGFR behavior and formed large clusters within which HER3 was phosphorylated via a noncanonical mechanism. HER3 phosphorylation by HER2 in the presence of NRG proceeded through still another mechanism and involved the formation of clusters within which receptor phosphorylation depended on asymmetric kinase dimerization. Our results demonstrate that the higher-order organization of HER receptors is an essential feature of their ligand-induced behavior and plays an essential role in lateral cross-activation of the receptors. We also show that HER receptor ligands exert unique effects on signaling by modulating this behavior.

Blockade of vascular endothelial growth factor receptors by tivozanib has potential anti-tumour effects on human glioblastoma cells

Glioblastoma (GBM) remains one of the most fatal human malignancies due to its high angiogenic and infiltrative capacities. Even with optimal therapy including surgery, radiotherapy and temozolomide, it is essentially incurable. GBM is among the most neovascularised neoplasms and its malignant progression associates with striking neovascularisation, evidenced by vasoproliferation and endothelial cell hyperplasia. Targeting the pro-angiogenic pathways is therefore a promising anti-glioma strategy. Here we show that tivozanib, a pan-inhibitor of vascular endothelial growth factor (VEGF) receptors, inhibited proliferation of GBM cells through a G2/M cell cycle arrest via inhibition of polo-like kinase 1 (PLK1) signalling pathway and down-modulation of Aurora kinases A and B, cyclin B1 and CDC25C. Moreover, tivozanib decreased adhesive potential of these cells through reduction of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Tivozanib diminished GBM cell invasion through impairing the proteolytic cascade of cathepsin B/urokinase-type plasminogen activator (uPA)/matrix metalloproteinase-2 (MMP-2). Combination of tivozanib with EGFR small molecule inhibitor gefitinib synergistically increased sensitivity to gefitinib. Altogether, these findings suggest that VEGFR blockade by tivozanib has potential anti-glioma effects in vitro. Further in vivo studies are warranted to explore the anti-tumour activity of tivozanib in combinatorial approaches in GBM.

Prognostic Impact of mRNA Expression Levels of HER1-4 (ERBB1-4) in Patients with Locally Advanced Rectal Cancer

Background. No predictive or prognostic biomarker is available for patients with locally advanced rectal cancer (LARC) undergoing perioperative chemoradiotherapy (CRT). Members of the human epidermal growth factor receptor (HER) family of receptor tyrosine kinases EGFR (HER1, ERBB1), HER2 (ERBB2), HER3 (ERBB3), and HER4 (ERBB4) are therapeutic targets in several cancers. The analysis was performed to assess expression levels and study the potential prognostic impact for disease-free and overall survival in patients with LARC. Patients and Methods. ERBB1–4 mRNA expression and tumor proliferation using Ki-67 (MKI67) mRNA were evaluated using RT-quantitative PCR in paraffin-embedded tumor samples from 86 patients (median age: 63) treated with capecitabine or 5-fluorouracil-based CRT within a phase 3 clinical trial. Results. A positive correlation of HER4 and HER2, HER3 and HER2, and HER4 and HER3 with each other was observed. Patients with high mRNA expression of ERBB1 (EGFR, HER1) had significantly increased risk for recurrence and death. Patients with high mRNA expression of MKI67 had reduced risk for relapse. Conclusion. This analysis suggests a prognostic impact of both ERBB1 and MKi67 mRNA expression in LARC patients treated with capecitabine or fluorouracil-based chemoradiotherapy.

Overexpression of PY1289-HER3 in sporadic pulmonary carcinoid from patients bearing MEN1 gene variants

The present study aimed to investigate the expression of human epidermal growth factor receptors (HERs) (HER1/HER2/HER3/HER4) and their phosphorylated forms (p-HER1/p-HER2/p-HER3/p-HER4) in pulmonary carcinoids (PCs). HER and p-HER protein expression was assessed by immunohistochemistry on tissue microarrays in 37 specimens of sporadic PCs, 29 typical carcinoids (TCs) and 8 atypical carcinoids (ACs). When compared with the ACs, the TCs did not exhibit any differences in terms of HER/p-HER expression. The tumors of this study have previously been characterized for the expression of menin and the mutational status of menin 1 (MEN1), a gene strongly implicated in the pathogenesis of PCs. In the present study, it was found that the cytoplasmic (‘disarrayed’), but not nuclear (‘arrayed’) expression of menin was positively correlated with HER3 (P=0.004), HER4 (P=0.015), p-HER1 (P=0.005), p-HER3 (P<0.001), and p-HER4 (P=0.001) expression. Moreover, HER3 and p-HER3 were found to be significantly more expressed in PCs with MEN1 variants, than in tumors with MEN1 wild-type (P=0.000 and P=0.025, respectively). These findings suggest the potential clinical use of HER inhibitors in the treatment of patients with PCs, particularly for individuals with p-HER3-positive PCs harboring MEN1 gene variants.

HSP70 Inhibition Limits FAK-Dependent Invasion and Enhances the Response to Melanoma Treatment with BRAF Inhibitors

The stress-inducible chaperone protein HSP70 (HSPA1) is implicated in melanoma development, and HSP70 inhibitors exert tumor-specific cytotoxic activity in cancer. In this study, we documented that a significant proportion of melanoma tumors express high levels of HSP70, particularly at advanced stages, and that phospho-FAK (PTK2) and BRAF are HSP70 client proteins. Treatment of melanoma cells with HSP70 inhibitors decreased levels of phospho-FAK along with impaired migration, invasion, and metastasis in vitro and in vivo Moreover, the HSP70 inhibitor PET-16 reduced levels of mutant BRAF, synergized with the BRAF inhibitor PLX4032 in vitro, and enhanced the durability of response to BRAF inhibition in vivo Collectively, these findings provide strong support for HSP70 inhibition as a therapeutic strategy in melanoma, especially as an adjuvant approach for overcoming the resistance to BRAF inhibitors frequently observed in melanoma patients. Cancer Res; 76(9); 2720-30. ©2016 AACR.

Heregulin-HER3-HER2 signaling promotes matrix metalloproteinase-dependent blood-brain-barrier transendothelial migration of human breast cancer cell lines

HER2-positive breast tumors are associated with a high risk of brain relapse. HER3 is thought to be an indispensible signaling substrate for HER2 (encoded by ERBB2) and is induced in breast cancer-brain metastases, though the molecular mechanisms by which this oncogenic dimer promotes the development of brain metastases are still elusive. We studied the effects of the HER3-HER2 ligand, heregulin (neuregulin-1, broadly expressed in the brain), on luminal breast cancer cell lines in vitro. Treatment of SKBr3 (ERBB2-amplified), MDA-MB-361 (ERBB2-amplified, metastatic brain tumor-derived) and MCF7 (HER2-positive, not ERBB2-amplified) cells with exogenous heregulin increased proliferation and adhesive potential, concomitant with induction of cyclin D1 and ICAM-1, and suppression of p27. All three cell lines invaded through matrigel toward a heregulin chemotactic signal in transwell experiments, associated with activation of extracellular cathepsin B and matrix metalloproteinase-9 (MMP-9). Moreover, heregulin induced breast cancer cell transmigration across a tight barrier of primary human brain microvascular endothelia. This was dependent on the activity of HER2, HER3 and MMPs, and was completely abrogated by combination HER2-HER3 blockade using Herceptin^® and the humanized HER3 monoclonal antibody, EV20. Collectively these data suggest mechanisms by which the HER3-HER2 dimer promotes development of metastatic tumors in the heregulin-rich brain microenvironment.

EGFR mutations are associated with higher incidence of distant metastases and smaller tumor size in patients with non-small-cell lung cancer based on PET/CT scan

The study aimed to explore the correlation of epidermal growth factor receptor (EGFR) mutation with tumor node metastasis (TNM) stage in patients with non-small-cell lung cancer (NSCLC) who underwent positron emission tomography/computed tomography (PET/CT) scan. Patients diagnosed with NSCLC who underwent EGFR mutation status testing and PET/CT or PET/CT plus brain magnetic resonance imaging scan at initial diagnosis in Nanfang Hospital between July 2010 and June 2014 were consecutively enrolled. The correlation of EGFR mutation status with TNM stage and distant metastasis organs including brain, bone, liver, pleural, adrenals and contralateral lobe of lung were analyzed. A total of 401 patients were enrolled. Tumor size in EGFR mutation group was significantly smaller than the wild-type group (P < 0.001). Further, patients with EGFR mutations were demonstrated significantly more frequent in patients with distant metastasis than non-metastasis (45.7 vs 32.2 %, P = 0.007). The rates of bone (32.2 vs 22.8 %, P = 0.007) and brain (16.3 vs 9.4 %, P = 0.008) metastasis were significantly higher in EGFR mutation group than the wild-type group. In the subgroup of 199 metastatic NSCLC patients, patients with EGFR mutation were significantly associated with a smaller tumor size (P = 0.013) and earlier N stage (P = 0.033). Of note, compared with the EGFR wild-type group, patients had a higher likelihood of developing brain plus bone metastases at initial diagnosis of EGFR mutation group (20.9 vs 7.5 %, P = 0.018). Taken together, we identify that EGFR mutations might associate with more aggressive tumor progression than the wild types in NSCLC. In addition, patients with tumor having EGFR mutation had a smaller tumor size than without mutation.

PAX3 and FOXD3 Promote CXCR4 Expression in Melanoma

Metastatic melanoma is an aggressive and deadly disease. The chemokine receptor CXCR4 is active in melanoma metastasis, although the mechanism for the promotion and maintenance of CXCR4 expression in these cells is mostly unknown. Here, we find melanoma cells express two CXCR4 isoforms, the common version and a variant that is normally restricted to cells during development or to mature blood cells. CXCR4 expression is driven through a highly conserved intronic enhancer element by the transcription factors PAX3 and FOXD3. Inhibition of these transcription factors slows melanoma cell growth, migration, and motility, as well as reduces CXCR4 expression. Overexpression of these transcription factors drives the production of increased CXCR4 levels. Loss of PAX3 and FOXD3 transcription factor activity results in a reduction in cell motility, migration, and chemotaxis, all of which are rescued by CXCR4 overexpression. Here, we discover a molecular pathway wherein PAX3 and FOXD3 promote CXCR4 gene expression in melanoma.

Clinical Translation and Validation of a Predictive Biomarker for Patritumab, an Anti-human Epidermal Growth Factor Receptor 3 (HER3) Monoclonal Antibody, in Patients With Advanced Non-small Cell Lung Cancer

Background

During early clinical development, prospective identification of a predictive biomarker and validation of an assay method may not always be feasible. Dichotomizing a continuous biomarker measure to classify responders also leads to challenges. We present a case study of a prospective–retrospective approach for a continuous biomarker identified after patient enrollment but defined prospectively before the unblinding of data. An analysis of the strengths and weaknesses of this approach and the challenges encountered in its practical application are also provided.

Methods

HERALD (NCT02134015) was a double-blind, phase 2 study in patients with non-small cell lung cancer (NSCLC) randomized to erlotinib with placebo or with high or low doses of patritumab, a monoclonal antibody targeted against human epidermal growth factor receptor 3 (HER3). While the primary objective was to assess safety and progression-free survival (PFS), a secondary objective was to determine a single predictive biomarker hypothesis to identify subjects most likely to benefit from the addition of patritumab. Although not identified as the primary biomarker in the study protocol, on the basis of preclinical results from 2 independent laboratories, expression levels of the HER3 ligand heregulin (HRG) were prospectively declared the predictive biomarker before data unblinding but after subject enrollment. An assay to measure HRG mRNA was developed and validated. Other biomarkers, such as epidermal growth factor receptor (EGFR) mutation status, were also evaluated in an exploratory fashion. The cutoff value for high vs. low HRG mRNA levels was set at the median delta threshold cycle. A maximum likelihood analysis was performed to evaluate the provisional cutoff. The relationship of HRG values to PFS hazard ratios (HRs) was assessed as a measure of internal validation. Additional NSCLC samples were analyzed to characterize HRG mRNA distribution.

Results

The subgroup of patients with high HRG mRNA levels (“HRG-high”) demonstrated clinical benefit from patritumab treatment with HRs of 0.37 (P = 0.0283) and 0.29 (P = 0.0027) in the high- and low-dose patritumab arms, respectively. However, only 102 of the 215 randomized patients (47.4%) had sufficient tumor samples for HRG mRNA measurement. Maximum likelihood analysis showed that the provisional cutoff was within the optimal range. In the placebo arm, the HRG-high subgroup demonstrated worse prognosis compared with HRG-low. A continuous relationship was observed between increased HRG mRNA levels and lower HR. Additional NSCLC samples (N = 300) demonstrated a similar unimodal distribution to that observed in this study, suggesting that the defined cutoff may be applicable to future NSCLC studies.

Conclusions

The prospective–retrospective approach was successful in clinically validating a probable predictive biomarker. Post hoc in vitro studies and statistical analyses permitted further testing of the underlying assumptions. However, limitations of this analysis include the incomplete collection of adequate tumor tissue and a lack of stratification. In a phase 3 study, findings are being confirmed, and the HRG cutoff value is being further refined.

ClinicalTrials.gov Number

NCT02134015.

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High heregulin levels predict benefit from patritumab treatment in patients with NSCLC.

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A prospective–retrospective approach provisionally validated a predictive biomarker.

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Post hoc analyses can be used to test underlying assumptions in biomarker validation.

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The median may be a reasonable initial cutoff for a unimodal continuous biomarker.

HER-3 peptide vaccines/mimics: Combined therapy with IGF-1R, HER-2, and HER-1 peptides induces synergistic antitumor effects against breast and pancreatic cancer cells

The human epidermal growth factor receptor 3 (HER-3/ErbB3) is a unique member of the human epidermal growth factor family of receptors, because it lacks intrinsic kinase activity and ability to heterodimerize with other members. HER-3 is frequently upregulated in cancers with epidermal growth factor receptor (EGFR/HER-1/ErbB1) or human epidermal growth factor receptor 2 (HER-2/ErBB2) overexpression, and targeting HER-3 may provide a route for overcoming resistance to agents that target EGFR or HER-2. We have previously developed vaccines and peptide mimics for HER-1, HER-2 and vascular endothelial growth factor (VEGF). In this study, we extend our studies by identifying and evaluating novel HER-3 peptide epitopes encompassing residues 99-122, 140-162, 237-269 and 461-479 of the HER-3 extracellular domain as putative B-cell epitopes for active immunotherapy against HER-3 positive cancers. We show that the HER-3 vaccine antibodies and HER-3 peptide mimics induced antitumor responses: inhibition of cancer cell proliferation, inhibition of receptor phosphorylation, induction of apoptosis and antibody dependent cellular cytotoxicity (ADCC). Two of the HER-3 epitopes 237-269 (domain II) and 461-479 (domain III) significantly inhibited growth of xenografts originating from both pancreatic (BxPC3) and breast (JIMT-1) cancers. Combined therapy of HER-3 (461-471) epitope with HER-2 (266-296), HER-2 (597-626), HER-1 (418-435) and insulin-like growth factor receptor type I (IGF-1R) (56-81) vaccine antibodies and peptide mimics show enhanced antitumor effects in breast and pancreatic cancer cells. This study establishes the hypothesis that combination immunotherapy targeting different signal transduction pathways can provide effective antitumor immunity and long-term control of HER-1 and HER-2 overexpressing cancers.

IL-24 gene transfer sensitizes melanoma cells to erlotinib through modulation of the Apaf-1 and Akt signaling pathways

Interleukin-24 (IL-24) is a novel tumor suppressor/cytokine gene expressed in normal human melanocytes but for which expression is nearly undetectable in metastatic melanoma. Overexpression of the IL-24 protein has been shown to inhibit tumor cell proliferation and induce apoptosis in many melanoma cell lines, and is now considered a tumor suppressor. Erlotinib, a small-molecule epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, has been widely studied for the treatment of human lung cancer and other solid tumors, but the erlotinib-targeted therapy has not been tested in melanoma. The objective of this study is to investigate the potency of erlotinib in suppressing the growth of human melanoma cells and whether IL-24 could enhance the antitumor activity of erlotinib. In cell viability and apoptosis assays, treatment with erlotinib dependently inhibited the growth of different melanoma cell lines and when combined with adenoviral vector-mediated IL-24 gene therapy, a significant increase in cell growth inhibition and apoptosis induction resulted (P<0.05). Immunoblot assay showed that the combination treatment of erlotinib and IL-24 considerably increased the cleavage of caspase-3 and caspase-9 and the expression of Apaf-1 protein in melanoma cells, inducing activation of the Apaf-1-dependent apoptotic pathways. Moreover, this combination treatment markedly inhibited phosphorylation of the EGFR, phosphatidylinositol-3 kinase, and Akt proteins, inactivating the Akt-dependent cell survival signaling pathway. These results show that a combination of IL-24-mediated molecular therapy and EGFR inhibitors such as erlotinib may be a promising treatment strategy for human melanoma and will serve as a basis for guiding the combination treatment designs in future preclinical and clinical trials.

ERBB3 is required for metastasis formation of melanoma cells

Melanoma is curable when it is at an early phase but is lethal once it becomes metastatic. The recent development of BRAF(V600E) inhibitors (BIs) showed great promise in treating metastatic melanoma, but resistance developed quickly in the treated patients, and these inhibitors are not effective on melanomas that express wild-type BRAF. Alternative therapeutic strategies for metastatic melanoma are urgently needed. Here we report that ERBB3, a member of the epidermal growth factor receptor family, is required for the formation of lung metastasis from both the BI-sensitive melanoma cell line, MA-2, and the BI-resistant melanoma cell line, 451Lu-R. Further analyses revealed that ERBB3 does not affect the initial seeding of melanoma cells in lung but is required for their further development into overt metastases, indicating that ERBB3 might be essential for the survival of melanoma cells after they reach the lung. Consistent with this, the ERBB3 ligand, NRG1, is highly expressed in mouse lungs and induces ERBB3-depdnent phosphorylation of AKT in both MA-2 and 451Lu-R cells in vitro. These findings suggest that ERBB3 may serve as a target for treating metastatic melanomas that are resistant to BIs. In support of this, administration of the pan-ERBB inhibitor, canertinib, significantly suppresses the metastasis formation of BI-resistant melanoma cell lines.

The nerve growth factor receptor CD271 is crucial to maintain tumorigenicity and stem-like properties of melanoma cells

Background

Large-scale genomic analyses of patient cohorts have revealed extensive heterogeneity between individual tumors, contributing to treatment failure and drug resistance. In malignant melanoma, heterogeneity is thought to arise as a consequence of the differentiation of melanoma-initiating cells that are defined by cell-surface markers like CD271 or CD133.

Results

Here we confirmed that the nerve growth factor receptor (CD271) is a crucial determinant of tumorigenicity, stem-like properties, heterogeneity and plasticity in melanoma cells. Stable shRNA mediated knock-down of CD271 in patient-derived melanoma cells abrogated their tumor-initiating and colony-forming capacity. A genome-wide expression profiling and gene-set enrichment analysis revealed novel connections of CD271 with melanoma-associated genes like CD133 and points to a neural crest stem cell (NCSC) signature lost upon CD271 knock-down. In a meta-analysis we have determined a shared set of 271 differentially regulated genes, linking CD271 to SOX10, a marker that specifies the neural crest. To dissect the connection of CD271 and CD133 we have analyzed 10 patient-derived melanoma-cell strains for cell-surface expression of both markers compared to established cell lines MeWo and A375. We found CD271⁺ cells in the majority of cell strains analyzed as well as in a set of 16 different patient-derived melanoma metastases. Strikingly, only 2/12 cell strains harbored a CD133⁺ sub-set that in addition comprised a fraction of cells of a CD271⁺/CD133⁺ phenotype. Those cells were found in the label-retaining fraction and in vitro deduced from CD271⁺ but not CD271 knock-down cells.

Conclusions

Our present study provides a deeper insight into the regulation of melanoma cell properties and points CD271 out as a regulator of several melanoma-associated genes. Further, our data strongly suggest that CD271 is a crucial determinant of stem-like properties of melanoma cells like colony-formation and tumorigenicity.

An ERBB3/ERBB2 oncogenic unit plays a key role in NRG1 signaling and melanoma cell growth and survival

We recently identified neuregulin-1 (NRG1) as a novel target of Notch1 required in Notch-dependent melanoma growth. ERBB3 and ERBB4, tyrosine kinase receptors specifically activated by NRG1, have been shown to be either elevated in melanoma cell lines and tumors or to be mutated in 20% of melanomas, respectively. While these data support key roles of NRG1 and its receptors in the pathogenesis of melanoma, whether ERBB3 and ERBB4 display redundant or exclusive functions is not known. Here, we show that ERBB3 and ERBB4 inhibition results in distinct outcomes. ERBB3 inhibition ablates the cellular responses to NRG1, results in AKT inactivation and leads to cell growth arrest and apoptotic cell death. In contrast, ERBB4 knockdown mildly affects cell growth, has no effects on cell survival and, importantly, does not alter the responses to NRG1. Finally, we identified ERBB2 as a key coreceptor in NRG1-dependent ERBB3 signaling. ERBB2 forms a complex with ERBB3, and its inhibition recapitulates the phenotypes observed upon ERBB3 ablation. We propose that an NRG1-ERBB3-ERBB2 signaling unit operates in melanoma cells where it promotes growth and survival.

HER3 overexpression is a prognostic indicator of extrahepatic cholangiocarcinoma

Members of the HER (ERBB) receptor protein tyrosine kinase family play an important role in regulating cellular division, proliferation, differentiation, and migration and have prognostic significance in a number of cancers. Here, we sought to define their role in extrahepatic cholangiocarcinoma (EHCC). HER2 and HER3 protein expression was studied in 230 EHCC cases using a tissue microarray and compared with clinicopathological variables, including the survival of EHCC patients. HER3 was predominantly localized to the cytoplasm, whereas HER2 exhibited a membranous expression pattern. Overexpression of HER2 and HER3 was observed in 6 % (13/224) and 39 % (90/230) of EHCCs, respectively. Membranous HER2 overexpression occurred more frequently in intraductal papillary neoplasms with an associated invasive carcinoma than in tubular adenocarcinomas (P = 0.02). HER3 protein was more commonly overexpressed in nodular and infiltrative than in papillary tumors (P = 0.03). HER3 overexpression was associated with decreased survival in both univariate (P = 0.01) and multivariate (P = 0.008) analyses, whereas HER2 overexpression was not associated with survival. HER2 and HER3 are overexpressed in subsets of EHCC patients. Notably, HER3 overexpression is correlated with decreased patient survival, suggesting that HER3 constitutes a prognostic factor as well as a potential candidate for targeted therapy.

Melanoma: from mutations to medicine

Melanoma is often considered one of the most aggressive and treatment-resistant human cancers. It is a disease that, due to the presence of melanin pigment, was accurately diagnosed earlier than most other malignancies and that has been subjected to countless therapeutic strategies. Aside from early surgical resection, no therapeutic modality has been found to afford a high likelihood of curative outcome. However, discoveries reported in recent years have revealed a near avalanche of breakthroughs in the melanoma field-breakthroughs that span fundamental understanding of the molecular basis of the disease all the way to new therapeutic strategies that produce unquestionable clinical benefit. These discoveries have been born from the successful fruits of numerous researchers working in many-sometimes-related, although also distinct-biomedical disciplines. Discoveries of frequent mutations involving BRAF(V600E), developmental and oncogenic roles for the microphthalmia-associated transcription factor (MITF) pathway, clinical efficacy of BRAF-targeted small molecules, and emerging mechanisms underlying resistance to targeted therapeutics represent just a sample of the findings that have created a striking inflection in the quest for clinically meaningful progress in the melanoma field.

Cutting edge in medical management of cutaneous oncology

Traditional chemotherapy has resulted in only a modest response, if any, for the 3 most common cutaneous malignancies of basal cell carcinoma, squamous cell carcinoma, and melanoma. Recent advances in understanding of the defects in the pathways driving tumorigenesis have changed the way that we think of these cancers and paved the way to targeted therapy for specific tumors. In this review, we will introduce the novel systemic treatments currently available for these cancers in the context of what is understood about the tumor pathogenesis. We will also introduce ongoing studies that will hopefully broaden our options for highly effective and tolerable treatment.

Histamine may induce airway remodeling through release of epidermal growth factor receptor ligands from bronchial epithelial cells

Asthma is a chronic inflammatory disease that is associated with airway remodeling, including hyperplasia of airway epithelial cells and airway smooth muscle cells, and goblet cell differentiation. We wished to address the potential role of histamine, a key biogenic amine involved in allergic reactions, in airway remodeling through the epidermal growth factor receptor (EGFR) pathway. Here, we demonstrate that histamine releases 2 EGFR ligands, amphiregulin and heparin-binding epidermal growth factor-like growth factor (HB-EGF), from airway epithelial cells. Amphiregulin and HB-EGF were expressed in airway epithelium of patients with asthma. Histamine up-regulated their mRNA expression (amphiregulin 3.2-fold, P<0.001; HB-EGF 2.3-fold, P<0.05) and triggered their release (amphiregulin EC(50) 0.50 μM, 31.2 ± 2.7 pg/ml with 10 μM histamine, P<0.01; HB-EGF EC(50) 0.54 μM, 78.5 ± 1.8 pg/ml with 10 μM histamine, P<0.001) compared to vehicle control (amphiregulin 19.3 ± 0.9 pg/ml; HB-EGF 60.2 ± 1.0 pg/ml), in airway epithelial cells. Histamine increased EGFR phosphorylation (2.1-fold by Western blot analysis) and induced goblet cell differentiation (CLCA1 up-regulation by real-time qPCR) in normal human bronchial epithelial (NHBE) cells. Moreover, amphiregulin and HB-EGF caused proliferation and migration of both NHBE cells and human airway smooth muscle cells. These results suggest that histamine may induce airway remodeling via the epithelial-derived EGFR ligands amphiregulin and HB-EGF.

Neuregulin-1 (Nrg1) is mainly expressed in rat pituitary gonadotroph cells and possibly regulates prolactin (PRL) secretion in a juxtacrine manner

The binding of Neuregulin-1 (Nrg1) to its cognate receptors ErbB-3 and -4 mediates intercellular and intracellular communication. In vitro, this interaction has been shown to control prolactin (PRL) secretion from pituitary tumour cells. However, Nrg1/ErbB signalling and its function in vivo are not well understood. In the present study, we demonstrated that type I and III Nrg1 isoforms were expressed in the rat anterior pituitary. We observed that Nrg1 positive gonadotrophs can form contacts with lactotrophs, which are positive for ErbB-3 receptor. In addition, we show that gonadotroph cell-derived Nrg1 regulates the secretion of an 18 kDa form of PRL from pituitary lactosomatotroph GH3 cells in vitro. The results obtained strongly suggest that gonadotrophs are the major source of Nrg1 in the normal anterior pituitary and that Nrg1 may function as a paracrine/juxtacrine regulator of PRL secretion.

The validation of matrix metalloproteinase-9 mRNA gene expression as a predictor of outcome in patients with metastatic gastric cancer

BACKGROUND

The prognostic role of matrix metalloproteinase-9 (MMP-9) in metastatic gastric cancer has not been validated.

PATIENTS AND METHODS

We carried out a molecular analysis in 222 metastatic gastric cancer patients obtained from clinical trials. We assessed the messenger RNA (mRNA) expression of MMP-9, vascular endothelial growth factor receptor-A, and epidermal growth factor receptor in a training cohort of 130 patients and conducted an independent validation in 92 patients. Automated RNA extraction from paraffin and RT-quantitative PCR was used. Immunohistochemistry for MMP-9 and diverse immune cell infiltrates was conducted.

RESULTS

In the training cohort, only MMP-9 significantly correlated with patient's survival. At the cut-off with the highest predictive value, 19% of patients had MMP-9 expression above this cut-off and these showed a median survival of 3.6 months compared with 10.5 months (P=1.7e(-6)) in patients with lower expression. Corresponding 1- and 2-year survivals were 9% and 44% and 0 and 21%, respectively. The application of this cut-off to the validation cohort revealed similar distributions of overall survival according to MMP-9 expression on uni- (P<0.001) and multivariate analyses (P<0.001). No differences in survival according to MMP-9 below best cut-off were found. MMP-9 protein assessed by immunohistochemistry was not prognostic.

CONCLUSION

MMP-9 mRNA expression above a certain cut-off level is associated with dismal survival.

EGFR-dependent pancreatic carcinoma cell metastasis through Rap1 activation

Tyrosine kinase receptors play an essential role in various aspects of tumor progression. In particular, epidermal growth factor receptor (EGFR) and its ligands have been implicated in the growth and dissemination of a wide array of human carcinomas. Here, we describe an EGFR-mediated signaling pathway that regulates human pancreatic carcinoma cell invasion and metastasis, yet does not influence the growth of primary tumors. In fact, ligation/activation of EGFR induces Src-dependent phosphorylation of two critical tyrosine residues of p130CAS, leading to assembly of a CAS/Nck1 complex that promotes Rap1 signaling. Importantly, GTP loading of Rap1 is specifically required for pancreatic carcinoma cell migration on vitronectin, but not on collagen. Furthermore, Rap1 activation is required for EGFR-mediated metastasis in vivo without impacting primary tumor growth. These findings identify a molecular pathway that promotes the invasive/metastatic properties of human pancreatic carcinomas driven by EGFR.

Cutaneous melanoma: a model to study cancer metastasis

Nodal status in melanoma is a critically important prognostic factor for patient outcome. The survival rate drops to <10% when melanoma has spread beyond the regional lymph nodes and includes visceral involvement. In general, the process of melanoma metastasis is progressive in that dissemination of melanoma from the primary site to the regional lymph nodes occurs prior to systemic disease. The goal of this review article is to describe melanoma as a clinical model to study cancer metastasis. A future challenge is to develop a molecular taxonomy to subgroup melanoma patients at various stages of tumor progression for more accurate targeted treatment.

EGFR in melanoma: clinical significance and potential therapeutic target

BACKGROUND

The role of epidermal growth factor receptor (EGFR) has been established in a range of neoplasms. In melanoma, data on EGFR protein expression are conflicting. Fluorescence in situ hybridization (FISH) analysis for EGFR gene expression in melanoma showed EGFR gene amplification to be linked with worse prognosis. Cetuximab has been shown to suppress the formation of metastasis in mice.

METHODS

EGFR protein expression and gene copy number status were evaluated by means of immunohistochemistry and FISH in melanoma samples of patients with known clinicopathological data. Associations between EGFR expression and prognostic parameters were investigated. The effect of different cetuximab concentrations on the BLM melanoma cell line was evaluated by means of methyl tetrazolium (MTT), sulforhodamine B (SRB) and Matrigel invasion assays.

RESULTS

EGFR protein expression was more frequently observed in patients with a positive sentinel lymph node. However, EGFR immunostaining has no predictive value. The presence of EGFR polysomy was associated with thicker tumors. Treatment of the BLM melanoma cell line with different concentrations of cetuximab reduced the invasive capacity of the cells, but did not alter cell viability or growth.

CONCLUSION

EGFR appears to be involved in progression and metastasis of a subset of melanomas. Targeting EGFR could therefore represent a therapeutic option for these melanomas.