Cytogenetic analysis of HER1/EGFR, HER2, HER3 and HER4 in 278 breast cancer patients

ERBB3 targeting: A promising approach to overcoming cancer therapeutic resistance

Human epidermal growth factor receptor-3 (ERBB3) is a member of the ERBB receptor tyrosine kinases (RTKs) and is expressed in many malignancies. Along with other ERBB receptors, ERBB3 is associated with regulating normal cell proliferation, apoptosis, differentiation, and survival, and has received increased research attention for its involvement in cancer therapies. ERBB3 expression or co-expression levels have been investigated as predictive factors for cancer prognosis and drug sensitivity. Additionally, the association between the elevated expression of ERBB3 and treatment failure in cancer therapy further established ERBB3-targeting therapy as a crucial therapeutic approach. This review delves into the molecular mechanisms of ERBB3-driven resistance to targeted therapeutics against ERBB2 and EGFR and other signal transduction inhibitors, endocrine therapy, chemotherapy, and radiotherapy. Using preclinical and clinical evidence, we synthesise and explicate how various aspects of aberrant ERBB3 activities-such as compensatory activation, signal crosstalk interactions, dysregulation in the endocytic pathway, mutations, ligand-independent activation, intrinsic kinase activity, and homodimerisation-can lead to resistance development and/or treatment failures. Several ERBB3-directed monoclonal antibodies, bispecific antibodies, and the emerging antibody-drug conjugate demonstrate encouraging clinical outcomes for improving therapeutic efficacy and overcoming resistance, especially when combined with other anti-cancer approaches. More research efforts are needed to identify appropriate biomarkers tailored for ERBB3-targeted therapies.

HER4 Affects Sensitivity to Tamoxifen and Abemaciclib in Luminal Breast Cancer Cells and Restricts Tumor Growth in MCF-7-Based Humanized Tumor Mice

The impact of the HER4 receptor on the growth and treatment of estrogen receptor-positive breast cancer is widely uncertain. Using CRISPR/Cas9 technology, we generated stable HER4 knockout variants derived from the HER4-positive MCF-7, T-47D, and ZR-75-1 breast cancer cell lines. We investigated tumor cell proliferation as well as the cellular and molecular mechanisms of tamoxifen, abemaciclib, AMG232, and NRG1 treatments as a function of HER4 in vitro. HER4 differentially affects the cellular response to tamoxifen and abemaciclib treatment. Most conspicuous is the increased sensitivity of MCF-7 in vitro upon HER4 knockout and the inhibition of cell proliferation by NRG1. Additionally, we assessed tumor growth and immunological effects as responses to tamoxifen and abemaciclib therapy in humanized tumor mice (HTM) based on MCF-7 HER4-wildtype and the corresponding HER4-knockout cells. Without any treatment, the enhanced MCF-7 tumor growth in HTM upon HER4 knockout suggests a tumor-suppressive effect of HER4 under preclinical but human-like conditions. This phenomenon is associated with an increased HER2 expression in MCF-7 in vivo. Independent of HER4, abemaciclib and tamoxifen treatment considerably inhibited tumor growth in these mice. However, abemaciclib-treated hormone receptor-positive breast cancer patients with tumor-associated mdm2 gene copy gains or pronounced HER4 expression showed a reduced event-free survival. Evidently, the presence of HER4 affects the efficacy of tamoxifen and abemaciclib treatment in different estrogen receptor-positive breast cancer cells, even to different extents, and is associated with unfavorable outcomes in abemaciclib-treated patients.

Complementary Tumor Diagnosis by Single Cell-Based Cytogenetics Using Multi-marker Fluorescence In Situ Hybridization (mFISH)

Multi-color (or multi-marker) fluorescence in situ hybridization (mFISH) is a well-established, valuable, complementary tool for prenatal and pathological (tumor) diagnosis. A variety of chromosomal abnormalities, such as partial or total chromosomal gains, losses, inversions, or translocations, which are considered to cause genetic syndromes, can relatively easily be detected on a cell-by-cell basis. Individual cells either in suspension (e.g., in the form of a cytological specimen derived from body fluids) or within a tissue (e.g., a solid tumor specimen or biopsy) can be quantitatively evaluated with respect to the chromosomal hybridization markers of interest (e.g., a gene or centromeric region) and with due consideration of cellular heterogeneity. FISH is helpful or even essential for the (sub-)classification, stratification, and unambiguous diagnosis of a number of malignant diseases and contributes to treatment decision in many cases. Here, the diagnostic power and limitations of typical FISH and mFISH approaches (except chromosome painting and RNA hybridization) are discussed, with special emphasis on tumor and single-cell diagnostics. Well-established and novel FISH protocols, the latter addressed to accelerate and flexibilize the preparation and hybridization of formalin-fixed and paraffin-embedded tissues, are provided. Moreover, guidelines and molecular aspects important for data interpretation are discussed. Finally, sophisticated multiplexed approaches and those that analyze very rare single-cell events, which are not yet implemented in diagnostic procedures, will be touched upon. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: (m)FISH applied to formaldehyde-fixed paraffin-embedded tissues Basic Protocol 2: (m)FISH applied to cytological specimens.

ERBB2 Amplification as a Predictive and Prognostic Biomarker in Upper Tract Urothelial Carcinoma

Upper tract urothelial carcinomas (UTUCs) occur in about 5-10% of all urothelial carcinomas and are frequently discovered in high-stage disease. We aimed to evaluate human epidermal growth factor receptor 2 (ERBB2) protein expression immunohistochemically and ERBB2 amplification in UTUCs by fluorescence in situ hybridization, applying a tissue microarray technique. ERBB2 overexpression and ERBB2 amplification were defined according to the recommendations of the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) for breast cancer and gastric carcinoma (GC), revealing scores of 2+ and 3+ in 10.2% and 41.8% of UTUCs, respectively. The performance parameters showed obviously higher sensitivity of ERBB2 immunoscoring according to the ASCO/CAP criteria for GC. ERBB2 amplification was detected in 10.5% of UTUCs. ERBB2 overexpression was more likely to be found in high-grade tumors and was associated with tumor progression. Univariable Cox regression analysis revealed a significantly lower progression-free survival (PFS) in cases with ERBB2 immunoscores of 2+ or 3+ according to the ASCO/CAP guidelines for GC. UTUCs with ERBB2 amplification showed a significantly shorter PFS in the multivariable Cox regression analysis. Irrespective of their ERBB2 status, patients with UTUC treated with platin showed a significantly lower PFS than UTUC patients who had not received any platin-based therapy. In addition, UTUC patients with a normal ERBB2 gene status who had not received platin-based therapy showed significantly longer overall survival. The results suggest that ERBB2 is a biomarker for progression in UTUCs and may define a distinct subgroup of UTUCs. As previously shown, ERBB2 amplification is infrequent. However, the small number of patients diagnosed with ERBB2-amplified UTUC might benefit from ERBB2-targeted cancer therapy. In clinical-pathological routine diagnostics, the determination of ERBB2 amplification is an established method in some defined entities and also successful in small samples. Still, the simultaneous use of ERBB2 immunohistochemistry and ERBB2 in situ hybridization would be important in order to record the low rate of amplified UTUC cases as completely as possible.

Beyond HER2: Targeting the ErbB receptor family in breast cancer

Targeting the HER2 oncogene represents one of the greatest advances in the treatment of breast cancer. HER2 is one member of the ERBB-receptor family, which includes EGFR (HER1), HER3 and HER4. In the presence or absence of underling genomic aberrations such as mutations or amplification events, intricate interactions between these proteins on the cell membrane lead to downstream signaling that encourages cancer growth and proliferation. In this Review, we contextualize efforts to pharmacologically target the ErbB receptor family beyond HER2, with a focus on EGFR and HER3. Preclinical and clinical efforts are synthesized. We discuss successes and failures of this approach to date, summarize lessons learned, and propose a way forward that invokes new therapeutic modalities such as antibody drug conjugates (ADCs), combination strategies, and patient selection through rational biomarkers.

"Shedding" light on HER4 signaling in normal and malignant breast tissues

Receptor Tyrosine Kinases of the Epidermal Growth Factor Receptor Family play a pivotal role as drivers of carcinogenesis and uncontrolled cell growth for a variety of malignancies, not least for breast cancer. Besides the estrogen receptor, the HER2 receptor was and still is a representative marker for advanced taxonomic sub-differentiation of breast cancer and emerged as one of the first therapeutic targets for antibody based therapies. Since the approval of trastuzumab for the therapy of HER2-positive breast cancer in 1998 anti-HER2 treatment strategies are being modified, refined, and successfully combined with complementary treatments, nevertheless there is still potential for improvement. The HER2 relatives, namely HER1 (i.e., EGFR), HER3 and HER4 share a high degree of molecular homology and together form a functional unit for signal transmission. Under regular conditions, receptor coexpression patterns and receptor interaction represent key parameters for signaling robustness, which ensures cellular growth control and enables tissue differentiation. In addition, treatment efficiency of e.g., an anti-HER2 targeting is substantially determined by the expression pattern of HER receptors on target cells. Within the receptor family, the HER4 plays a particular role and is engaged in exceptional signaling activities. A favorable prognostic impact has been attributed to HER4 expression in breast cancer under specific molecular conditions. HER4-specific cellular effects are initially determined by a ligand-dependent or -independent receptor activation. Essential processes as cell growth and proliferation, cell differentiation, and apoptotic cell death can be initiated by this receptor. This review gives an overview of the role of HER4 in normal and malignant breast epithelial cells and tissues. Specific mechanism of HER4 activation and subsequent intracellular signaling will be described by taking a focus on effects provoked by receptor shedding. HER4 activities and specific effects will be correlated to breast cancer subtypes and the impact of HER4 on course and outcome of disease will be considered. Moreover, current and potential therapeutic approaches will be discussed.

Neuregulin 4 Boosts the Efficacy of Anti-ERBB2 Neutralizing Antibodies

ERBB4 is a tyrosine kinase receptor reported to exert both oncogenic and tumor suppressor activities. These paradoxical effects were suggested to stem from different ERBB4 homo-/hetero-dimers and/or isoforms. By stratifying breast cancer patients for clinical and molecular subtypes and ERBB4 mRNA abundance, we here report that higher ERBB4 levels correlate with longer relapse-free survival in breast cancer patients of HER2-enriched and luminal A molecular subtypes, proposing a cancer-protecting role for this receptor in these specific subgroups. We also observed that HER2-enriched breast cancers express intermediate ERBB4 mRNA levels compared to luminal and triple-negative/basal-like subgroups, which displayed the highest and the lowest levels, respectively. Inspired by these clinical data, we tested the activation of ERBB4 by Neuregulins as a potential anticancer strategy for HER2+ breast cancers. To this end, we employed two HER2+ breast cancer cellular models (BT474 and SKBR3), which express intermediate/high and low ERBB4 levels, respectively. Cell proliferation and motility were evaluated on these cellular models following treatments with Neuregulin 1 (NRG1), which activates both ERBB3 and ERBB4, or Neuregulin 4 (NRG4), which specifically activates ERBB4. Both NRG1 and NRG4 were used alone or in combination with anti-ERBB2 neutralizing antibodies, namely trastuzumab and pertuzumab. In vitro treatment with NRG1 on BT474 cells restrained cell growth and reduced the anti-proliferative efficacy of trastuzumab. In contrast, treatment with NRG1 on SKBR3 cells increased cell proliferation and migration, and partially or completely impaired the anti-proliferative/anti-migratory action of trastuzumab and/or pertuzumab. Importantly, in both the cell lines, treatment with NRG4 robustly potentiated the anti-proliferative action of trastuzumab and pertuzumab. Collectively, our data in HER2+ breast cancer cells highlight that NRG1 may exert both pro- and anti-proliferative effects, and may reduce the efficacy of anti-HER2 agents, whereas NRG4 may boost the anti-proliferative effects of anti-ERBB2 agents. We propose a provocative paradigm shift in the field of growth factors in cancer progression, suggesting the administration of ERBB4 ligands, such as Neuregulin 4, as a strategy to improve the efficacy of anti-ERBB2 agents.

The Yin and Yang of ERBB4: Tumor Suppressor and Oncoprotein

ERBB4 (HER4) is a member of the ERBB family of receptor tyrosine kinases, a family that includes the epidermal growth factor receptor (EGFR/ERBB1/HER1), ERBB2 (Neu/HER2), and ERBB3 (HER3). EGFR and ERBB2 are oncoproteins and validated targets for therapeutic intervention in a variety of solid tumors. In contrast, the role that ERBB4 plays in human malignancies is ambiguous. Thus, here we review the literature regarding ERBB4 function in human malignancies. We review the mechanisms of ERBB4 signaling with an emphasis on mechanisms of signaling specificity. In the context of this signaling specificity, we discuss the hypothesis that ERBB4 appears to function as a tumor suppressor protein and as an oncoprotein. Next, we review the literature that describes the role of ERBB4 in tumors of the bladder, liver, prostate, brain, colon, stomach, lung, bone, ovary, thyroid, hematopoietic tissues, pancreas, breast, skin, head, and neck. Whenever possible, we discuss the possibility that ERBB4 mutants function as biomarkers in these tumors. Finally, we discuss the potential roles of ERBB4 mutants in the staging of human tumors and how ERBB4 function may dictate the treatment of human tumors. SIGNIFICANCE STATEMENT: This articles reviews ERBB4 function in the context of the mechanistic model that ERBB4 homodimers function as tumor suppressors, whereas ERBB4-EGFR or ERBB4-ERBB2 heterodimers act as oncogenes. Thus, this review serves as a mechanistic framework for clinicians and scientists to consider the role of ERBB4 and ERBB4 mutants in staging and treating human tumors.

A Review of HER4 (ErbB4) Kinase, Its Impact on Cancer, and Its Inhibitors

HER4 is a receptor tyrosine kinase that is required for the evolution of normal body systems such as cardiovascular, nervous, and endocrine systems, especially the mammary glands. It is activated through ligand binding and activates MAPKs and PI3K/AKT pathways. HER4 is commonly expressed in many human tissues, both adult and fetal. It is important to understand the role of HER4 in the treatment of many disorders. Many studies were also conducted on the role of HER4 in tumors and its tumor suppressor function. Mostly, overexpression of HER4 kinase results in cancer development. In the present article, we reviewed the structure, location, ligands, physiological functions of HER4, and its relationship to different cancer types. HER4 inhibitors reported mainly from 2016 to the present were reviewed as well.

Efficacy of targeted therapy in patients with HER2-positive non-small cell lung cancer: A systematic review and meta-analysis

Anti-human epidermal growth factor receptor 2 (HER2) therapy is an effective treatment for HER2-positive gastric and breast malignancies. However, the efficacy of HER2-targeted therapy in non-small cell lung cancer (NSCLC) patients with HER2 alterations remains controversial. We searched studies on HER2-targeted therapy in NSCLC patients that reported objective response rate (ORR), disease control rate (DCR) and progressionfree survival (PFS) published from database inception to 30 May 2021. A total of 32 trials involving 958 patients were included. The ORRs of HER2-TKIs targeted therapy, humanised monoclonal antibody, trastuzumab-based treatment and antibody-drug conjugate (ADC) (T-DM1) were 22% (95% CI 11-31), 23% (95% CI 20-65), 26% (95% CI 14-39) and 16% (95% CI _6-37), while that of ADC (DS-8201) was 60% (95% CI 35-85). The DCRs of these groups were 59% (95% CI 49-69), 39% (95% CI _9-88), 63% (95% CI 37-89), 31% (95% CI 4-58) and 87% (95% CI 62-112), respectively. In the subgroup analysis, numerically higher ORRs and DCRs were observed in the poziotinib (38%; 75%) and pyrotinib (35%; 83%) groups. The median PFSs of these groups were 5.51 months, 3.09 months, 4.61 months, 2.65 months and 12.04 months, respectively. HER2-targeted therapy can be considered an acceptable treatment strategy for NSCLC patients with HER2 alterations. In particular, ADC (DS-8201), pyrotinib and poziotinib demonstrated promising anti-tumour activity in HER2-positive NSCLC.

Targeting HER2 genomic alterations in non-small cell lung cancer

Oncogenic mutations and amplifications in the erythroblastic oncogene B (ERBB2), or human epidermal growth factor receptor 2 (HER2), have emerged as distinct oncogenic drivers and drug targets in non-small cell lung cancer (NSCLC). Each genomic alteration occurs in 2-4% of NSCLC by next generation sequencing and is associated with constitutive HER2 activation. The most common HER2 mutations in NSCLC are exon 20 mutation A775_G776insYVMA mutation in the kinase domain and S310F mutation in the extracellular domain. Unlike in breast and gastric cancer, HER2 protein overexpression in NSCLC is not validated to be a biomarker predictive of clinical response to HER2-targeted agents. High HER2 protein overexpression by immunohistochemistry (3+) only occurs in 2-4% of NSCLC. Until now HER2-targeted agents (such as afatinib and ado-trastuzumab emtansine) only demonstrate modest clinical activity in patients with HER2-mutant NSCLC. Retrospective studies show concern for inferior clinical benefit of immune checkpoint inhibitors in HER2-mutated NSCLC. Therefore, platinum-based chemotherapy with or without an anti-angiogenesis inhibitor remains the first line standard treatment for this patient population. In May 2020 trastuzumab deruxtecan (T-DXd) received the U.S. Food and Drug Administration breakthrough therapy designation for HER2-mutant metastatic NSCLC, and was added as an option for HER2-mutant NSCLC to the NCCN guidelines V1.2021. A global phase III study of pyrotinib compared to docetaxel as a second line therapy for advanced NSCLC harboring HER2 exon 20 mutations was just opened for enrollment in September 2020. In this review, we highlight the current knowledge and perspectives on targeting-HER2 genomic alterations in NSCLC.

Therapeutic Advances in Oncology

Around 77 new oncology drugs were approved by the FDA in the past five years; however, most cancers remain untreated. Small molecules and antibodies are dominant therapeutic modalities in oncology. Antibody-drug conjugates, bispecific antibodies, peptides, cell, and gene-therapies are emerging to address the unmet patient need. Advancement in the discovery and development platforms, identification of novel targets, and emergence of new technologies have greatly expanded the treatment options for patients. Here, we provide an overview of various therapeutic modalities and the current treatment options in oncology, and an in-depth discussion of the therapeutics in the preclinical stage for the treatment of breast cancer, lung cancer, and multiple myeloma.

A novel rabbit derived anti-HER2 antibody with pronounced therapeutic effectiveness on HER2-positive breast cancer cells in vitro and in humanized tumor mice (HTM)

Background

Antibody based cancer therapies have achieved convincing success rates combining enhanced tumor specificity and reduced side effects in patients. Trastuzumab that targets the human epidermal growth factor related receptor 2 (HER2) is one of the greatest success stories in this field. For decades, trastuzumab based treatment regimens are significantly improving the prognosis of HER2-positive breast cancer patients both in the metastatic and the (neo-) adjuvant setting. Nevertheless, ≥ 50% of trastuzumab treated patients experience de-novo or acquired resistance. Therefore, an enhanced anti-HER2 targeting with improved treatment efficiency is still aspired.

Methods

Here, we determined cellular and molecular mechanisms involved in the treatment of HER2-positive BC cells with a new rabbit derived HER2 specific chimeric monoclonal antibody called “B100″. We evaluated the B100 treatment efficiency of HER2-positive BC cells with different sensitivity to trastuzumab both in vitro and in the presence of a human immune system in humanized tumor mice.

Results

B100 not only efficiently blocks cell proliferation but more importantly induces apoptotic tumor cell death. Detailed in vitro analyses of B100 in comparison to trastuzumab (and pertuzumab) revealed equivalent HER2 internalization and recycling capacity, similar Fc receptor signaling, but different HER2 epitope recognition with high binding and treatment efficiency. In trastuzumab resistant SK-BR-3 based humanized tumor mice the B100 treatment eliminated the primary tumor but even more importantly eradicated metastasized tumor cells in lung, liver, brain, and bone marrow.

Conclusion

Overall, B100 demonstrated an enhanced anti-tumor activity both in vitro and in an enhanced preclinical HTM in vivo model compared to trastuzumab or pertuzumab. Thus, the use of B100 is a promising option to complement and to enhance established treatment regimens for HER2-positive (breast) cancer and to overcome trastuzumab resistance. Extended preclinical analyses using appropriate models and clinical investigations are warranted.

Working together for the family: determination of HER oncogene co-amplifications in breast cancer

HER2 is a well-studied tyrosine kinase (TK) membrane receptor which functions as a therapeutic target in invasive ductal breast carcinomas (IDC). The standard of care for the treatment of HER2-positive breast is the antibody trastuzumab. Despite specific treatment unfortunately, 20% of primary and 70% of metastatic HER2 tumors develop resistance. HER2 belongs to a gene family, with four members (HER1-4) and these members could be involved in resistance to anti-HER2 therapies. In this study we designed a probemix to detect the amplification of the four HER oncogenes in a single reaction. In addition, we developed a protocol based on the combination of MLPA with ddPCR to detect the tumor proportion of co-amplified HERs. On 111 IDC, the HER2 MLPA results were validated by FISH (Adjusted r ² = 0,91, p < 0,0001), CISH (Adjusted r ² = 0,938, p < 0,0001) and IHC (Adjusted r ² = 0,31, p < 0,0001). HER1-4 MLPA results were validated by RT-qPCR assays (Spearman Rank test p < 0,05). Of the 111 samples, 26% presented at least one HER amplified, of which 23% showed co-amplifications with other HERs. The percentage of cells with HER2 co-amplified varied among the tumors (from 2-72,6%). Independent in-silico findings show that the outcome of HER2+ patients is conditioned by the status of HER3 and HER4. Our results encourage further studies to investigate the relationship with patient's response to single or combined treatment. The approach could serve as proof of principle for other tumors in which the HER oncogenes are involved.

Critical role of EphA3 in cancer and current state of EphA3 drug therapeutics

The erythropoietin-producing human hepatocellular (Eph) receptors are transmembrane glycoprotein members of the tyrosine kinase receptors family. The Ephs may bind to various ephrin ligands resulting in the phosphorylation of their tyrosine kinase domain and the activation of the Eph receptor. In this review we focus on EphA3, one receptor of the 14 different Ephs, as it carries out both redundant and restricted functions in the germline development of mammals and in the maintenance of various adult tissues. The loss of EphA3 regulation is correlated with various human malignancies, the most notable being cancer. This receptor is overexpressed and/or mutated in multiple tumors, and is also associated with poor prognosis and decreased survival in patients. Here we highlight the role of EphA3 in normal and malignant tissues that are specific to cancer; these include hematologic disorders, gastric cancer, glioblastoma multiforme, colorectal cancer, lung cancer, renal cell carcinoma, and prostate cancer. Moreover, various anticancer agents against EphA3 have been developed to either inhibit its kinase domain activity or to function as agonists. Thus, we examine the most potent small molecule drugs and mAb-based therapeutics against EphA3 that are currently in pre-clinical or clinical stages.

ErbB4 3'-UTR Variant (c.*3622A>G) is Associated with ER/PR Negativity and Advanced Breast Cancer

A genetic variant may alter a gene expression level and as a result be associated with pathological characteristics in breast cancer. In this research, the frequency and association of the ErbB4 3'-untranslated region (3'-UTR) variant, rs12471583 (c.*3622A>G) was studied in an Iranian breast cancer patients. In silico assessment was performed to predict the function of the rs12471583 variant located on the 3'-UTR of ErbB4. Furthermore, as a case-control study, this polymorphism was genotyped in 243 breast cancer patients and non-cancerous controls using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. The Armitage's trend test and regular association tests were performed to analyze a possible association between the rs12471583 and risk of breast cancer and its relevant pathological traits. The bioinformatics analysis predicted that the rs12471583 SNP is located on the four miRNA binding sites, including miR-511-5p, miR-4659a-5p, miR-4659b-5p, and miR-6830-3p. According to logistic regression tests, the G allele is negatively associated with ER- (OR = 0.20, 95% C.I. = 0.04-0.93, p = 0.026), PR- (OR = 0.31, 95% C.I. = 0.10-0.98, p = 0.039), ER-/PR- (OR = 0.20, 95% C.I. = 0.04-0.93, p = 0.026), and advanced breast cancer (OR = 0.40, 95% C.I. = 0.18-0.85, p = 0.016). It has been found that ErbB4 expression may be linked to unfavorable outcomes in breast cancer. Likewise, our results suggest that the G allele may strengthen miRNA-ErbB4 binding efficiency and as a result reduce expression of ErbB4. This is a possible explanation for the observed association.

Target HER four in breast cancer?

The HER4 receptor tyrosine kinase is known to have promiscuous activity in malignant cells, last but not least in breast cancer. Evidently, the prognostic and predictive impact of HER4 expression depends on the expression of different receptor isotypes, the way of receptor activation (ligand dependent vs. independent), and on the complex interaction of the HER4 intracellular domain (4ICD) with intracellular regulative molecules which results in either oncogenic or rather tumor suppressive HER4 activity. Recent data suggest that HER4 unfavorably affects the endocrine treatment of postmenopausal breast cancer patients with tamoxifen and therefore might represent an additional therapeutic target in luminal breast cancer.

Application of Multiplex Ligation-Dependent Probe Amplification in Determining the Copy Number Alterations of HER Gene Family Members in Invasive Ductal Breast Carcinoma

BACKGROUND

The aim of this study was to assess the usability of multiplex ligation-dependent probe amplification (MLPA) for copy number determination of HER gene family members (ERBB1-4) in invasive breast carcinoma and to explore the association of ERBB1-4 gene copy numbers with clinicopathological characteristics of breast cancer (BC) patients.

METHODS

Clinical and immunohistochemical characteristics were assessed in 104 BC patients and the molecular subtype was determined for each tumor sample. Furthermore, HER-2/neu status was assessed by immunohistochemistry (IHC) and equivocal results were confirmed by Fluorescent in situ hybridization (FISH). The copy numbers of ERBB1-4 genes were determined by MLPA.

RESULTS

Twenty-five percent of all patients showed ERBB2 gene-amplification by MLPA, whereas 14.4% of cases showed ERBB-2/neu overproduction at the protein level (IHC). Moreover, only 2.9% and 1.9% of patients showed amplification in ERBB1 and ERBB4, respectively. No copy number changes were observed in ERBB3. Our results indicated a significant association between ERBB2 copy number gain and histological grade (p value= 0.01), stage (p value= 0.02), and tumor subtypes (p value= <0.001). In addition, we found MLPA more accurate in assessing HER2 status with 15.4% and 9.6% gene amplification detection in early stages (1, 2A and 2B) and advanced tumor stages (3A, 3B, and 4), respectively, compared to IHC (early stages= 13.5% and advanced stages= 4.7%).

CONCLUSION

According to our findings, MLPA is a fast, precise and low-cost technique to detect ERBB2 amplification, especially in advanced tumor stages. However, due to infrequent amplification found in ERBB1 and ERBB4 as well as the lack of amplification in ERBB3, their importance in the prognostic evaluation of BC patients remains controversial.

Development of Effective Therapeutics Targeting HER3 for Cancer Treatment

HER3 is the third member of the human epidermal growth factor receptor (HER/EGFR) family, and unlike its other family members, is unique due to its minimal intrinsic kinase activity. As a result, HER3 has to interact with another receptor tyrosine kinase (RTK), such as EGFR or HER2, in order to activate the PI-3 K/Akt, MEK/MAPK, Jak/Stat pathways, as well as Src kinase. Over-expression of HER3 in various human cancers promotes tumor progression by increasing metastatic potential and acting as a major cause of treatment failure. Effective inhibition of HER3, and/or the key downstream mediators of HER3 signaling, is thought to be required to overcome resistance and enhance therapeutic efficacy. To date, there is no known HER3-targeted therapy that is approved for breast cancer, with a number of anti-HER3 antibodies current in various stages of development and clinical testing. Recent data suggests that the epigenetic strategy of using a histone deacetylase (HDAC) inhibitor, or functional cooperative miRNAs, may be an effective way to abrogate HER3 signaling. Here, we summarize the latest advances in our understanding of the mechanism of HER3 signaling in tumor progression, with continuing research towards the identification of therapeutic anti-HER3 antibodies. We will also examine the potential to develop novel epigenetic approaches that specifically target the HER3 receptor, along with important key downstream mediators that are involved in cancer treatment.

Comparison of Antibodies for Immunohistochemistry-based Detection of HER3 in Breast Cancer

BACKGROUND

Growth factor receptor HER3 (ErbB3) lacks standardized immunohistochemistry (IHC)-based methods for formalin-fixed paraffin-embedded (FFPE) tissue samples. We compared 4 different anti-HER3 antibodies to explain the differences found in the staining results reported in the literature.

MATERIALS AND METHODS

Four commercial HER3 antibodies were tested on FFPE samples including mouse monoclonal antibody clones, DAK-H3-IC and RTJ1, rabbit monoclonal antibody clone SP71, and rabbit polyclonal antibody (SAB4500793). Membranous and cytoplasmic staining patterns were analyzed and scored as 0, 1+, or 2+ according to the intensity of the staining and completeness of membranous and cytoplasmic staining. A large collection of HER2-amplified breast cancers (n=177) was stained with the best performing HER3 antibody. The breast cancer cell line, MDA-453, and human prostate tissue were used as positive controls. IHC results were confirmed by analysis of flow cytometry performed on breast cancer cell lines. Staining results of FFPE samples were compared with samples fixed with an epitope-sensitive fixative (PAXgene).

RESULTS

Clear circumferential cell membrane staining was found only with the HER3 antibody clone DAK-H3-IC. Other antibodies (RTJ1, SP71, and polyclonal) yielded uncertain and nonreproducible staining results. In addition to cell membrane staining, DAK-H3-IC was also localized to the cytoplasm, but no nuclear staining was observed. In HER2-amplified breast cancers, 80% of samples were classified as 1+ or 2+ according to the HER3 staining on the cell membrane. The results from FFPE cell line samples were comparable to those obtained from unfixed cells in flow cytometry. IHC conducted on FFPE samples and on PAXgene-fixed samples showed equivalent results.

CONCLUSIONS

We conclude that IHC with the monoclonal antibody, DAK-H3-IC, on FFPE samples is a reliable staining method for use in translational research. Assessment of membranous HER3 expression may be clinically relevant in selecting patients who may most benefit from pertuzumab or other novel anti-HER3 therapies.

EGF Level in Hepatoid Gland Adenomas and Hepatoid Gland Epitheliomas in Dogs After Administering Tamoxifen

BACKGROUND/AIM

Neoplastic lesions of perianal glands account for approximately 10% of all skin cancer cases in dogs. They occur in many dog breeds, usually in male animals aged over 6 years. Due to their hormone-dependency, tamoxifen can be used in antineoplastic treatment. The aim of the study was to measure epidermal growth factor (EGF) levels in the serum of dogs with perianal tumours after tamoxifen treatment and to use it as a prognostic factor for further treatment.

MATERIALS AND METHODS

The study was performed on 19 male dogs aged between 6 and 14 years, diagnosed with neoplastic hyperplasia in the perianal region. The control group comprised 10 healthy dogs brought in for routine castration. The research material comprised blood drawn from the animals and tumour specimens for histopathology. The study group received 1-month treatment with tamoxifen. Blood serum was then tested for 17-β oestradiol level, and for EGF level on the first day of the therapy and 6 months after treatment completion.

RESULTS

Hepatoid gland adenomas were diagnosed in 10 cases, and hepatoid gland epitheliomas in nine cases. Elevated 17-β oestradiol levels were observed in all dogs. On the first day of treatment with tamoxifen, the serum EGF levels in all study groups were higher than in the control group. At the 6-month follow-up, the EGF levels were significantly reduced in hepatoid gland adenoma cases compared to those taken on the first day of treatment of tamoxifen, while in animals with hepatoid gland epithelioma, it was greatly increased and was correlated with relapse.

CONCLUSION

Perianal gland tumours are characterised by EGF overexpression, which can be helpful in early-stage prognosis and treatment. An increase in EGF levels 6 months after tamoxifen therapy correlates with disease progression and may be a useful prognostic factor.

Evaluation of the prognostic value of all four HER family receptors in patients with metastatic breast cancer treated with trastuzumab: A Hellenic Cooperative Oncology Group (HeCOG) study

In the current study, we performed a complete analysis, with four different methods, of all four HER family receptors, in a series of patients with metastatic breast cancer treated with trastuzumab-based regimens and evaluated their prognostic value. Formalin-fixed paraffin-embedded tumor tissue samples were collected from 227 patients, considered to be HER2-positive when assessed at the local laboratories. We evaluated gene amplification, copy number variations (CNVs), mRNA and protein expression of all four HER family members. In addition, our analysis included the evaluation of several other factors by immunohistochemistry (IHC), such as pHER2^Tyr1221/1222, pHER2^Tyr877 and PTEN. Central review of HER2 status by IHC and fluorescence in situ hybridization revealed that of the 227 patients, only 139 (61.2%) were truly HER2-positive. Regarding the 191 patients treated with trastuzumab as first-line therapy, median time to progression (TTP) was 15.3 and 10.4 months for HER2-positive and HER2-negative participants, respectively, whereas median survival was 50.4 and 38.1 months, respectively. In HER2-positive patients, high HER3 mRNA expression was of favorable prognostic significance for TTP and survival (HR = 0.43, 95% CI 0.21–0.88, Wald’s p = 0.022 and HR = 0.43, 95% CI 0.21–0.88, p = 0.021, respectively), while EGFR copy gain and EGFR protein expression were associated with higher risk for disease progression in HER2-negative patients (HR = 3.53, 95% CI 1.19–10.50, p = 0.023 and HR = 3.37, 95% CI 1.12–10.17, p = 0.031, respectively). Positive HER3 protein expression was a favorable factor for TTP in HER2-negative patients (HR = 0.43, 95% CI 0.22–0.84, p = 0.014). In the multivariate analysis, only EGFR copy gain retained its prognostic significance for TTP in the HER2-negative population (HR = 3.96, 95% CI 1.29–12.16, p = 0.016), while high HER3 mRNA expression retained its favorable prognostic significance for TTP in the HER2-positive subgroup (HR = 0.47, 95% CI 0.23–0.99, p = 0.048). The present study suggests that EGFR copy gain represents a negative prognostic factor for TTP in HER2-negative patients with metastatic breast cancer treated with trastuzumab. In addition, high HER3 mRNA expression appears to be of favorable prognostic significance for TTP in HER2-positive patients. Given the small number of patients included in the current analysis and the retrospective nature of the study, our findings should be validated in larger cohorts.

HER4 expression in estrogen receptor-positive breast cancer is associated with decreased sensitivity to tamoxifen treatment and reduced overall survival of postmenopausal women

BACKGROUND

The sensitivity of estrogen receptor-positive breast cancers to tamoxifen treatment varies considerably, and the molecular mechanisms affecting the response rates are manifold. The human epidermal growth factor receptor-related receptor HER2 is known to trigger intracellular signaling cascades that modulate the activity of coregulators of the estrogen receptor which, in turn, reduces the cell sensitivity to tamoxifen treatment. However, the impact of HER2-related receptor tyrosine kinases HER1, HER3, and, in particular, HER4 on endocrine treatment is largely unknown.

METHODS

Here, we retrospectively evaluated the importance of HER4 expression on the outcome of tamoxifen- and aromatase inhibitor-treated estrogen receptor-positive breast cancer patients (n = 258). In addition, we experimentally analyzed the efficiency of tamoxifen treatment as a function of HER4 co-expression in vitro.

RESULTS

We found a significantly improved survival in tamoxifen-treated postmenopausal breast cancer patients in the absence of HER4 compared with those with pronounced HER4 expression. In accordance with this finding, the sensitivity to tamoxifen treatment of estrogen and HER4 receptor-positive ZR-75-1 breast cancer cells can be significantly enhanced by HER4 knockdown.

CONCLUSION

We suggest an HER4/estrogen receptor interaction that impedes tamoxifen binding to the estrogen receptor and reduces treatment efficiency. Whether the sensitivity to tamoxifen treatment can be enhanced by anti-HER4 targeting needs to be prospectively evaluated.

Clinicopathological and prognostic correlations of HER3 expression and its degradation regulators, NEDD4-1 and NRDP1, in primary breast cancer

Background

Human epidermal growth factor receptor HER3 (ErbB3), especially in association with its relative HER2 (ErbB2), is known as a key oncogene in breast tumour biology. Nonetheless, the prognostic relevance of HER3 remains controversial. NEDD4–1 and NRDP1 are signalling molecules closely related to the degradation of HER3 via ubiquitination. NEDD4–1 and NRDP1 have been reported to contribute to HER3-mediated signalling by regulating its localization and cell membrane retention. We studied correlations between HER3, NEDD4–1, and NRDP1 protein expression and their association with tumour histopathological characteristics and clinical outcomes.

Methods

The prevalence of immunohistochemically detectable expression profiles of HER3 (n = 177), NEDD4–1 (n = 145), and NRDP1 (n = 145) proteins was studied in primary breast carcinomas on archival formalin-fixed paraffin-embedded (FFPE) samples. Clinicopathological correlations were determined statistically using Pearson’s Chi-Square test. The Kaplan-Meier method, log-rank test (Mantel-Cox), and Cox regression analysis were utilized for survival analysis.

Results

HER3 protein was expressed in breast carcinomas without association with HER2 gene amplification status. Absence or low HER3 expression correlated with clinically aggressive features, such as triple-negative breast cancer (TNBC) phenotype, basal cell origin (cytokeratin 5/14 expression combined with ER negativity), large tumour size, and positive lymph node status. Low total HER3 expression was prognostic for shorter recurrence-free survival time in HER2-amplified breast cancer (p = 0.004, p = 0.020 in univariate and multivariate analyses, respectively). The majority (82.8%) of breast cancers demonstrated NEDD4–1 protein expression - while only a minor proportion (8.3%) of carcinomas expressed NRDP1. NEDD4–1 and NRDP1 expression were not associated with clinical outcomes in HER2-amplified breast cancer, irrespective of adjuvant trastuzumab therapy.

Conclusions

Low HER3 expression is suggested to be a valuable prognostic biomarker to predict recurrence in HER2-amplified breast cancer. Neither NEDD4–1 nor NRDP1 demonstrated relevance in prognostics or in the subclassification of HER2-amplified breast carcinomas.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4917-1) contains supplementary material, which is available to authorized users.

Sialic Acid-Binding Lectin from Bullfrog Eggs Exhibits an Anti-Tumor Effect Against Breast Cancer Cells Including Triple-Negative Phenotype Cells

Sialic acid-binding lectin from Rana catesbeiana eggs (cSBL) is a multifunctional protein that has lectin and ribonuclease activity. In this study, the anti-tumor activities of cSBL were assessed using a panel of breast cancer cell lines. cSBL suppressed the cell growth of all cancer cell lines tested here at a concentration that is less toxic, or not toxic at all, to normal cells. The growth suppressive effect was attributed to the cancer-selective induction of apoptosis. We assessed the expressions of several key molecules associated with the breast cancer phenotype after cSBL treatment by western blotting. cSBL decreased the expression level of estrogen receptor (ER) α, while it increased the phosphorylation level of p38 mitogen-activated protein kinase (MAPK). cSBL also suppressed the expression of the progesterone receptor (PgR) and human epidermal growth factor receptor type 2 (HER2). Furthermore, it was revealed that cSBL decreases the expression of the epidermal growth factor receptor (EGFR/HER1) in triple-negative breast cancer cells. These results indicate that cSBL induces apoptosis with decreasing ErbB family proteins and may have great potential for breast cancer chemotherapy, particularly in triple-negative phenotype cells.

ErbB4 receptor polymorphism 2368A>C and risk of breast cancer

PURPOSE

A number of single nucleotide polymorphisms (SNPs) in EebB4 gene have been studied, which has clarified their impact on breast cancer in different populations. Nevertheless, the importance of rs13423759 in breast cancer has not been studied and its effect remained almost unclear. In this paper, we evaluated the frequency of rs13423759 different alleles in Iranian population and statistically analyzed their association with breast cancer risk.

MATERIALS AND METHODS

Allele-specific Primer PCR (ASP-PCR) was recruited in this study to genotype rs13423759 position in 172 breast cancer and 148 healthy control subjects. The genotypes of control and cases were analyzed statistically to find the association between rs13423759 alleles and breast cancer incidence and its clinicopathological characteristics. In silico studies were performed in order to find the mechanistic viewpoint of rs13423759 alleles in breast cancer.

RESULTS

rs13423759 allele C was shown to be significantly associated with breast cancer risk, HER2 positivity and increased risk of metastasis. Reciprocally, allele A was correlated with the lowered risk of breast cancer. The in silico studies showed that rs13423759 allele C is capable to strengthen the interaction between miR-548as, an oncomiRNA, and ErbB4 mRNA, leading to its lowered concentration in the cells.

CONCLUSION

rs13423759 allele C is significantly associated with the enhanced risk of breast cancer, elevated metastasis and HER2 positivity.

The role of ErbB3 binding protein 1 in cancer: Friend or foe?

ErbB3, a member of the epidermal growth factor receptor family, reportedly plays an essential role in the regulation of cancer progression and therapeutic resistance. Numerous studies have indicated that ErbB3 binding protein 1 (Ebp1), a binding partner for ErbB3, plays an important regulatory role in the expression and function of ErbB3, but there is no agreement as to whether Ebp1 also has an ErbB3-independent function in cancer and how it might contribute to tumorigenesis. In this review, we will discuss the different functions of the two Ebp1 isoforms, p48 and p42, that may be responsible for the potentially dual role of Ebp1 in cancer growth.

Roles of human epidermal growth factor receptor family in pulmonary lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare and refractory disease that affects women of reproductive age. Several target therapies are used to manage LAM, but no curative modes of treatment have been reported yet. Therefore, in this study, we focused on targeting human epidermal growth factor receptor (HER) family proteins as a treatment strategy for LAM. In antibody array analysis, HER signaling was detected in the proteins extracted from LAM tissues. We then evaluated the expression of HER family members in 34 pulmonary LAM specimens using both immunohistochemistry and quantitative reverse-transcription polymerase chain reaction. Hierarchical clustering analysis was performed to classify the cases based on the immunohistochemistry results. Both epidermal growth factor receptor (EGFR) and HER4 were expressed in all 34 cases. HER3 was expressed in 25 of 34 cases, but HER2 was not expressed in any case. In addition, results of quantitative reverse-transcription polymerase chain reaction analysis confirmed the expression of EGFR and HER4 expression in LAM cells. Patients with HER3- or HER4-positive tissues were younger and had a history of pneumothorax. The cases were classified into 4 different clusters based on the results of hierarchical cluster analysis. One of these clusters was associated with EGFR, HER3, and HER4; the patients in this cluster were significantly younger and had a history of pneumothorax. These results indicated that HER family could contribute to the progression of pulmonary LAM, and treatments targeted against HER family might be effective for treating pulmonary LAM.

Understanding the biology of HER3 receptor as a therapeutic target in human cancer

HER3 belongs to the human epidermal growth factor receptor (HER) family which also includes HER1/EGFR/erbB1, HER2/erbB2, and HER4/erbB4. As a unique member of the HER family, HER3 lacks or has little intrinsic tyrosine kinase activity. It frequently co-expresses and forms heterodimers with other receptor tyrosine kinases (RTKs) in cancer cells to activate oncogenic signaling, especially the PI-3K/Akt pathway and Src kinase. Elevated expression of HER3 has been observed in a wide variety of human cancers and associates with a worse survival in cancer patients with solid tumors. Studies on the underlying mechanism implicate HER3 expression as a major cause of treatment failure in cancer therapy. Activation of HER3 signaling has also been shown to promote cancer metastasis. These data strongly support the notion that therapeutic inactivation of HER3 and/or its downstream signaling is required to overcome treatment resistance and improve the outcomes of cancer patients.

In silico prediction of ErbB signal activation from receptor expression profiles through a data analytics pipeline

The ErbB signalling pathway has been studied extensively owing to its role in normal physiology and its dysregulation in cancer. Reverse engineering by mathematical models use the reductionist approach to characterize the network components. For an emergent, system-level view of the network, we propose a data analytics pipeline that can learn from the data generated by reverse engineering and use it to re-engineer the system with an agent-based approach. Data from a kinetic model that estimates the parameters by fitting to experiments on cell lines, were encoded into rules, for the interactions of the molecular species (agents) involved in biochemical reactions. The agent model, a digital representation of the cell line system, tracks the activation of ErbB1-3 receptors on binding with ligands, resulting in their dimerization, phosphorylation, trafficking and stimulation of downstream signalling through P13-Akt and Erk pathways. The analytics pipeline has been used to mechanistically link HER expression profile to receptor dimerization and activation of downstream signalling pathways. When applied to drug studies, the efficacy of a drug can be investigated in silico. The anti-tumour activity of Pertuzumab, a monoclonal antibody that inhibits HER2 dimerization, was simulated by blocking 80% of the cellular HER2 available, to observe the effect on signal activation.

Human epidermal growth factor receptor 4 (HER4) is a favorable prognostic marker of breast cancer: a systematic review and meta-analysis

Based on a large cohort of clinical studies involving a total of 8024 patients and reporting the effects of HER4 on breast cancer prognosis, we conducted the first meta-analysis and review of this type. We identified 26 studies published between 1985 and 2016 and assessed the prognostic value of HER4 in breast cancer by either real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR, for mRNA levels) or immunohistochemistry (IHC, for protein levels). Elevated expression of HER4 was significantly associated with longer relapse-free survival (RFS) (HR = 0.63; CI: 0.48-0.83; P = 0.001, random effects). Further subgroup analysis showed that our results were stable irrespective of subtype [Luminal: HR = 0.40, CI: 0.30-0.53, P < 0.001, fixed effects; triple negative breast cancer (TNBC): HR = 0.49, CI: 0.26-0.90, P = 0.02, fixed effects; and HER2-positive: HR = 0.53, CI: 0.40-0.71, P < 0.001, fixed effects]. Cytoplasmic HER4 was more effective than nuclear HER4 (HR = 0.74, CI: 0.60-0.92, P = 0.007, fixed effects) for predicting RFS. HER4 was also found to be a favorable prognostic marker for overall survival (OS) among patients with non-TNBC in the subgroup analysis (Luminal: HR = 0.71, CI: 0.52-0.95, P = 0.023, fixed effects; HER2-positive: HR = 0.48, CI: 0.26-0.89, P = 0.020, fixed effects).

Regulation of Programmed Death Ligand 1 (PD-L1) Expression in Breast Cancer Cell Lines In Vitro and in Immunodeficient and Humanized Tumor Mice

Programmed death ligand 1 (PD-L1) expression is an efficient strategy of tumor cells to escape immunological eradiation. However, only little is known about the factors that affect the cellular expression levels. Here we assessed the PD-L1 expression on different breast cancer cell lines under standard in vitro culture conditions and as a function of Epirubicin or Paclitaxel treatment. Moreover, we evaluated the expression in immunodeficient tumor mice as well as in humanized tumor mice (i.e., in the presence of a human immune system). We found highest PD-L1 levels in JIMT-1 and MDA-MB-231 cells. Epirubicin treatment caused a decrease and Paclitaxel treatment an increased PD-L1 expression in MDA-MB-231 cells. In addition, we identified nuclear PD-L1 in MDA-MB-231 cells. All in vivo transplanted breast cancer cell lines downregulated PD-L1 expression compared to their in vitro counterpart. Neither the gene copy number nor the presence of human immune system in humanized tumor mice had an effect on the PD-L1 content. We demonstrate that the degree of PD-L1 expression amongst breast cancer cell lines varies considerably. In addition, cytotoxic treatments and other extrinsic parameters differentially affect the expression. Hence, further investigations including in vivo evaluations are necessary to understand PD-L1 regulation for advanced breast cancer stratification.

Prognostic Evaluation of Epidermal Growth Factor Receptor (EGFR) Genotype and Phenotype Parameters in Triple-negative Breast Cancers

BACKGROUND

Epidermal growth factor receptor (EGFR) aberrations have been implicated in the pathogenesis of triple-negative breast cancer (TNBC) but their impact on prognosis and, therefore, druggability, remain controversial. Herein, we studied EGFR aberrations at different molecular levels and assessed their prognostic impact in patients with operable TNBC treated with adjuvant anthracycline-based chemotherapy.

MATERIALS AND METHODS

We evaluated the prognostic impact of EGFR gene status by fluorescent in situ hybridization (FISH), EGFR coding mutations by Sanger and next-generation sequencing, relative EGFR messenger RNA (mRNA) levels by qPCR (upper quartile) and EGFR and p53 protein expression by immunohistochemistry (IHC), in 352 centrally-assessed tumors from an equal number of TNBC patients.

RESULTS

Approximately 53.5% of the tumors expressed EGFR, 59.3% p53 and 35.9% both EGFR and p53 proteins; 4.1% showed EGFR gene amplification and 4.4% carried EGFR mutations. The latter were located outside the druggable kinase domain region and presented at low frequencies. Amplification and mutations overlapped only in one case of glycogen-rich carcinoma. EGFR and CEN7 copies were higher in tumors from older patients (p=0.002 and p=0.003, respectively). Patients with amplified tumors (n=11) had excellent prognosis (0 relapses and deaths). Upon multivariate analysis, high EGFR copies conferred significantly favorable disease-free survival (HR=0.57, 95% CI 0.36-0.90, Wald's p=0.017) and high CEN7 copies favorable overall survival (HR=0.49, 95% CI=0.29-0.83, Wald's p=0.008). Patients with EGFR-/p53+ and EGFR+/p53- tumors had significantly higher risk for relapse than those with EGFR-/p53- and EGFR+/p53+ tumors (HR=1.73, 95% CI=1.12-2.67, Wald's p=0.013).

CONCLUSION

EGFR gene amplification and mutations are rare in TNBC, the latter of no apparent clinical relevance. Surrogate markers of EGFR-related chromosomal aberrations and combined EGFR/p53 IHC phenotypes appear to be associated with favorable prognosis in patients with operable TNBC receiving conventional adjuvant chemotherapy.

Diagnostic pathology of early systemic cancer: ERBB2 gene amplification in single disseminated cancer cells determines patient survival in operable esophageal cancer

Early metastatic dissemination and evolution of disseminated cancer cells (DCCs) outside the primary tumor is one reason for the failure of adjuvant therapies because it generates molecular genotypes and phenotypes different from primary tumors, which still underlie therapy decisions. Since ERBB2 amplification in esophageal DCCs but not in primary tumor cells predict outcome, we aimed to establish an assay with diagnostic reliability for single DCCs or circulating tumor cells. For this, we evaluated copy number alterations of more than 600 single DCCs from multiple cancer types to define reference regions suitable for quantification of target regions, such as ERBB2. We then compared ERBB2 quantitative PCR (qPCR) measurements with fluorescent in situ hybridization (FISH) data of various breast cancer cell lines and identified the aberration-calling threshold. The method was applied to two independent cohorts of esophageal cancer patients from Hamburg (n = 59) and Düsseldorf (n = 53). We found a high correlation between the single cell qPCR assay and the standard FISH assay (R = 0.98) and significant associations between amplification and survival for both patient cohorts (Hamburg (HH), p = 0.033; Düsseldorf (D), p = 0.052; pooled HH + D, p = 0.002) when applied to DCCs of esophageal cancer patients. Detection of a single ERBB2-amplified DCC was the most important risk factor for death from esophageal cancer (relative risk = 4.22; 95% CI = 1.91-9.32; p < 0.001). In our study, we detected ERBB2-amplified cells in 7% of patients. These patients could benefit from anti-ERBB2 targeting therapies.

The role of HER2, EGFR, and other receptor tyrosine kinases in breast cancer

Breast cancer affects approximately 1 in 8 women, and it is estimated that over 246,660 women in the USA will be diagnosed with breast cancer in 2016. Breast cancer mortality has decline over the last two decades due to early detection and improved treatment. Over the last few years, there is mounting evidence to demonstrate the prominent role of receptor tyrosine kinases (RTKs) in tumor initiation and progression, and targeted therapies against the RTKs have been developed, evaluated in clinical trials, and approved for many cancer types, including breast cancer. However, not all breast cancers are the same as evidenced by the multiple subtypes of the disease, with some more aggressive than others, showing differential treatment response to different types of drugs. Moreover, in addition to canonical signaling from the cell surface, many RTKs can be trafficked to various subcellular compartments, e.g., the multivesicular body and nucleus, where they carry out critical cellular functions, such as cell proliferation, DNA replication and repair, and therapeutic resistance. In this review, we provide a brief summary on the role of a selected number of RTKs in breast cancer and describe some mechanisms of resistance to targeted therapies.

Breast cancers with EGFR and HER2 co-amplification favor distant metastasis and poor clinical outcome

ErbB signaling serves essential roles in invasive ductal carcinoma (IDC). The aim of the present study was to assess gene amplification in ErbB family members in IDC with clinical implications. Quantitative polymerase chain reaction and fluorescence in situ hybridization were performed on formalin-fixed paraffin-embedded tumor samples for gene amplification detection. The clinical and histopathological characteristics, as well as the prognostic significance, were analyzed. Among the 119 IDC patients evaluated, epidermal growth factor receptor [EGFR; also known as human epidermal growth factor receptor (HER)1], HER2, HER3 and HER4 gene amplification was observed in 30 (25.2%), 44 (36.9%), 0 (0.0%) and 1 (0.8%) patients, respectively. EGFR amplification was associated with estrogen receptor status (P=0.028) and higher possibilities of recurrence (P=0.015) and distant metastasis (following initial surgery) (P=0.011). In survival analysis, EGFR amplification was also associated with disease-free survival (DFS) (P=0.001) and overall survival (OS) (P=0.003). HER2 amplification was associated with larger tumor size (P=0.006), later clinical stage (P=0.003) and distant metastasis (following initial surgery) (P=0.006). In survival analysis, HER2 amplification was also associated with DFS (P=0.011). Notably, the present study identified a group of patients in whom EGFR and HER2 were co-amplified. This group of patients appeared to have a higher possibility of metastasis (when diagnosed) (P=0.014) and distant metastasis (following initial surgery) (P<0.001). In survival analysis, these patients were noticed to be associated with DFS (P<0.001) and OS (P=0.002). With respect to treatment regimen, this was also true for the DFS association with chemotherapy (P<0.001), radiotherapy (P<0.001) and hormonal therapy (P=0.001). The present results suggest that EGFR and HER2 amplification favor distant metastasis following initial surgery and are significantly associated with poor clinical outcome in breast cancer patients.

Druggability and Binding Site Interaction Studies of Potential Metabolites Isolated from Marine Sponge Aurora globostellata against Human Epidermal Growth Factor Receptor-2

To study the involvement of compounds stigmasterol and oleic acid isolated from marine sponge Aurora globostellata and docking against the Human Epidermal Growth Factor Receptor-2 in breast cancer. The comparative molecular docking was performed with the natural compounds from marine sponge and the synthetic drugs used in breast cancer treatment against the target HER2. The molecular docking analysis was done using GLIDE in Schrodinger software package. The ADME properties were calculated using the Qikprop. The observation of the common binding site for all the ligands confirms the binding pocket; where the isolated compound Stigmasterol agrees well with the binding residues and thus can be optimized further to arrive at a molecule that has a high binding affinity and low binding constant. The results of the docking studies carried out on HER2 provide an insight for the compound stigmasterol to have drug like properties than oleic acid. These results are supportive to confirm the marine sponges as a better lead for cancer therapeutics.

Prognostic significance of HER3 in patients with malignant solid tumors

Human epidermal growth factor receptor 3 (HER3) is closely involved in tumor progression and is an important target of therapy. To evaluate the prognostic significance of HER3 in malignant solid tumors, we searched the PUBMED, EMBASE and CNKI databases for relevant studies written in English or Chinese up to December 2015. Fifteen studies comprising 2964 patients were identified. The HER3⁺ rate ranged from 9.0-75.1 % in malignant solid tumors: 30.3-75.1 % in breast cancers, 51.1-74.5 % in colorectal cancers, 13.7-59.0 % in gastric cancers, and 54.5-74.4 % in cervical cancers. For patients with a malignant solid tumor, the death risk was higher for those with a HER3⁺ tumor than for those with a HER3⁻ tumor (HR 1.60, 95% CI: 1.27 - 2.02, P < 0.001). Subgroup analysis revealed this was also the case for patients with digestive or gastric cancer (HR 1.78, P < 0.001; HR 2.18, P < 0.001). By contrast, HER3 had no prognostic significance in colorectal or breast cancer (HR 1.52, P = 0.296; HR 1.23, P = 0.108). HER3⁺ is thus associated with poor survival in overall and in gastric cancer. The prognostic significance of HER3⁺ in other tumors is uncertain and deserves further study.

Early clinical development of epidermal growth factor receptor targeted therapy in breast cancer

INTRODUCTION

Epidermal growth factor receptor (EGFR) targeted treatment has been evaluated but has not shown a clear clinical benefit for breast cancer. This review article aims to consider the knowledge of the biological background of EGFR pathways in dissecting clinical studies of EGFR targeted treatment in breast cancer. Areas covered: This review focuses on the role of the EGFR pathway and the investigational drugs that target EGFR for breast cancer. Expert opinion: Recent studies have indicated that EGFR targeted therapy for breast cancer has some promising effects for patients with triple-negative breast cancer, basal-like breast cancer, and inflammatory breast cancer. However, predictive and prognostic biomarkers for EGFR targeted therapy have not been identified. The overexpression or amplification of EGFR itself may not be the true factor of induction of the canonical pathway as an oncogenic driver of breast cancer. Instead, downstream, non-canonical pathways related to EGFR may contribute to some aspects of the biological behavior of breast cancer; therefore, the blockade of the receptor could result in sufficient suppression of downstream pathways to inhibit the aggressive behavior of breast cancer. Mechanistic studies to investigate the dynamic interaction between the EGFR pathway and non-canonical pathways are warranted.

Human epidermal growth factor receptor 4 (Her4) Suppresses p53 Protein via Targeting the MDMX-MDM2 Protein Complex: IMPLICATION OF A NOVEL MDMX SER-314 PHOSPHOSITE

Deregulated receptor tyrosine kinase (RTK) signaling is frequently associated with tumorigenesis and therapy resistance, but its underlying mechanisms still need to be elucidated. In this study, we have shown that the RTK human epidermal growth factor receptor 4 (Her4, also known as Erbb4) can inhibit the tumor suppressor p53 by regulating MDMX-mouse double minute 2 homolog (MDM2) complex stability. Upon activation by either overexpression of a constitutively active vector or ligand binding (Neuregulin-1), Her4 was able to stabilize the MDMX-MDM2 complex, resulting in suppression of p53 transcriptional activity, as shown by p53-responsive element-driven luciferase assay and mRNA levels of p53 target genes. Using a phospho-proteomics approach, we functionally identified a novel Her4-induced posttranslational modification on MDMX at Ser-314, a putative phosphorylation site for the CDK4/6 kinase. Remarkably, inhibition of Ser-314 phosphorylation either with Ser-to-Ala substitution or with a specific inhibitor of CDK4/6 kinase blocked Her4-induced stabilization of MDMX-MDM2 and rescued p53 activity. Our study offers insights into the mechanisms of deregulated RTK-induced carcinogenesis and provides the basis for the use of inhibitors targeting RTK-mediated signals for p53 restoration.

HER3, but Not HER4, Plays an Essential Role in the Clinicopathology and Prognosis of Gastric Cancer: A Meta-Analysis

Background and Aim

Human epidermal growth factor receptor (HER) family plays an important role in gastric cancer (GC), especially HER2. Too much attention has been paid to HER2; however, the functions of HER3 and HER4 overexpression in GC are always ignored. The clinicopathological and prognostic roles of HER3 and HER4 in GC are controversial. In this study, a systematic review and meta-analysis was conducted to evaluate the use of HER3 or HER4 as a predictor of clinicopathology and survival time in GC patients.

Methods

Eligible studies were searched on PubMed, Ovid, Web of Science, and Cochrane databases through multiple search strategies. Data collection and statistical analysis were carried out by the Revman 5.3 software. The Newcastle-Ottawa scale was used to assess the quality of included studies.

Results

A total of 448 studies about HER3 overexpression and GC, and 398 studies about HER4 overexpression and GC were searched. Of these, 5 eligible studies about HER3 including 1016 GC patients and 3 eligible studies about HER4 including 793 GC patients met the inclusion criteria. The results showed that HER3 and HER4 overexpression were significantly associated with depth of tumor invasion (OR = 0.44, 95%CI 0.29–0.67, P = 0.0002 and OR = 0.50, 95%CI 0.38–0.86, P = 0.007) and lymph node metastasis (OR = 0.40, 95%CI 0.20–0.77, P = 0.007 and OR = 0.57, 95%CI 0.38–0.86, P = 0.007), and HER3 overexpression reveals a tendency of later tumor node metastases (TNM) stage (OR = 0.50, 95%CI 0.22–1.15, P = 0.10) and predicts a worse survival time (RR = 0.71, 95%CI 0.61–0.84, P<0.00001), while HER4 overexpression had no correlation with TNM stage (OR = 0.60, 95%CI 0.20–1.78) and survival time (RR = 1.09, 95%CI 0.91–1.30).

Conclusions

This meta-analysis indicated that HER3 plays an essential role in the clinicopathology and prognosis of GC. However, HER4 may not be an ideal prognostic factor for GC.

Recent trends in microRNA research into breast cancer with particular focus on the associations between microRNAs and intrinsic subtypes

MicroRNAs (miRNAs) are short non-coding RNAs that regulate the function of target genes at the post-transcriptional phase. miRNAs are considered to have roles in the development, progression and metastasis of cancer. Recent studies have indicated that particular miRNA signatures are correlated with tumor aggressiveness, response to drug therapy and patient outcome in breast cancer. On the other hand, in routine clinical practice, the treatment regimens for breast cancer are determined based on the intrinsic subtype of the primary tumor. Previous studies have shown that miRNA expression profiles of each intrinsic subtypes of breast cancer differ. In hormone receptor-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer, miRNA expressions are found to be correlated with endocrine therapy resistance, progesterone receptor expression and heat shock protein activity. Some miRNAs are associated with resistance to HER2-targeted therapy and HER3 expression in HER2-positive breast cancer. In triple-negative breast cancer, miRNA expressions are found to be associated with BRCA mutations, immune system, epithelial-mesenchymal transition, cancer stem cell properties and androgen receptor expression. As it has been clarified that the expression levels and functions of miRNA differ among the various subtypes of breast cancer, and it is necessary to take account of the characteristics of each breast cancer subtype during research into the roles of miRNA in breast cancer. In addition, the discovery of the roles played by miRNAs in breast cancer might provide new opportunities for the development of novel strategies for diagnosing and treating breast cancer.