Signal transduction and oncogenesis by ErbB/HER receptors

Identification of the active compounds and significant pathways of yinchenhao decoction based on network pharmacology

Yinchenhao decoction (YCHD) is a traditional Chinese medicine formulation, which has been widely used for the treatment of jaundice for 2,000 years. Currently, YCHD is used to treat various liver disorders and metabolic diseases, however its chemical/pharmacologic profiles remain to be elucidated. The present study identified the active compounds and significant pathways of YCHD based on network pharmacology. All of the chemical ingredients of YCHD were retrieved from the Traditional Chinese Medicine Systems Pharmacology database. Absorption, distribution, metabolism and excretion screening with oral bioavailability (OB) screening, drug-likeness (DL) and intestinal epithelial permeability (Caco-2) evaluation were applied to discover the bioactive compounds in YCHD. Following this, target prediction, pathway identification and network construction were employed to clarify the mechanism of action of YCHD. Following OB screening, and evaluation of DL and Caco-2, 34 compounds in YCHD were identified as potential active ingredients, of which 30 compounds were associated with 217 protein targets. A total of 31 significant pathways were obtained by performing enrichment analyses of 217 proteins using the JEPETTO 3.x plugin, and 16 classes of gene-associated diseases were revealed by performing enrichment analyses using Database for Annotation, Visualization and Integrated Discovery v6.7. The present study identified potential active compounds and significant pathways in YCHD. In addition, the mechanism of action of YCHD in the treatment of various diseases through multiple pathways was clarified.

Reversing EGFR Mediated Immunoescape by Targeted Monoclonal Antibody Therapy

Uncontrolled growth is a signature of carcinogenesis, in part mediated by overexpression or overstimulation of growth factor receptors. The epidermal growth factor receptor (EGFR) mediates activation of multiple oncogenic signaling pathways and escape from recognition by the host immune system. We discuss how EGFR signaling downregulates tumor antigen presentation, upregulates suppressive checkpoint receptor ligand programmed death ligand (PD-L1), induces secretion of inhibitory molecules such as transforming growth factor beta (TGFβ) and reprograms the metabolic pathways in cancer cells to upregulate aerobic glycolysis and lactate secretion that ultimately lead to impaired cellular immunity mediated by natural killer (NK) cell and cytotoxic T lymphocytes (CTL). Ultimately, our understanding of EGFR-mediated escape mechanisms has led us to design EGFR-specific monoclonal antibody therapies that not only inhibit tumor cell metabolic changes and intrinsic oncogenic signaling but also activates immune cells that mediate tumor clearance. Importantly, targeted immunotherapy may also benefit from combination with antibodies that target other immunosuppressive pathways such PD-L1 or TGFβ and ultimately enhance clinical efficacy.

Natural Products as Chemopreventive Agents by Potential Inhibition of the Kinase Domain in ErbB Receptors

Small molecules found in natural products provide therapeutic benefits due to their pharmacological or biological activity, which may increase or decrease the expression of human epidermal growth factor receptor (HER), a promising target in the modification of signaling cascades involved in excessive cellular growth. In this study, in silico molecular protein-ligand docking protocols were performed with AutoDock Vina in order to evaluate the interaction of 800 natural compounds (NPs) from the NatProd Collection (http://www.msdiscovery.com/natprod.html), with four human HER family members: HER1 (PDB: 2ITW), HER2 (PDB: 3PP0), HER3 (PDB: 3LMG) and HER4 (PDB: 2R4B). The best binding affinity values (kcal/mol) for docking pairs were obtained for HER1-podototarin (−10.7), HER2-hecogenin acetate (−11.2), HER3-hesperidin (−11.5) and HER4-theaflavin (−10.7). The reliability of the theoretical calculations was evaluated employing published data on HER inhibition correlated with in silico binding calculations. IC₅₀ values followed a significant linear relationship with the theoretical binding Affinity data for HER1 (R = 0.656, p < 0.0001) and HER2 (R = 0.543, p < 0.0001), but not for HER4 (R = 0.364, p > 0.05). In short, this methodology allowed the identification of several NPs as HER inhibitors, being useful in the discovery and design of more potent and selective anticancer drugs.

Oncogenic growth factor signaling mediating tumor escape from cellular immunity

Unrestrained growth factor signals can promote carcinogenesis, as well as other hallmarks of cancer such as immune evasion. Our understanding of the function and complex regulation of HER family of receptors has led to the development of targeted therapeutic agents that suppress tumor growth. However, these receptors also mediate escape from recognition by the host immune system. We discuss how HER family of oncogenic receptors downregulate tumor antigen presentation and upregulate suppressive membrane-bound or soluble secreted inhibitory molecules that ultimately lead to impaired cellular immunity mediated by cytotoxic T lymphocyte (CTL) recognition. Implementing this knowledge into new therapeutic strategies to enhance tumor immunogenicity may restore effector cell mediated immune clearance of tumors and clinical efficacy of tumor-targeted immunotherapy against HER receptor overexpression.

Epidermal Growth Factor Signaling towards Proliferation: Modeling and Logic Inference Using Forward and Backward Search

In biological systems, pathways define complex interaction networks where multiple molecular elements are involved in a series of controlled reactions producing responses to specific biomolecular signals. These biosystems are dynamic and there is a need for mathematical and computational methods able to analyze the symbolic elements and the interactions between them and produce adequate readouts of such systems. In this work, we use rewriting logic to analyze the cellular signaling of epidermal growth factor (EGF) and its cell surface receptor (EGFR) in order to induce cellular proliferation. Signaling is initiated by binding the ligand protein EGF to the membrane-bound receptor EGFR so as to trigger a reactions path which have several linked elements through the cell from the membrane till the nucleus. We present two different types of search for analyzing the EGF/proliferation system with the help of Pathway Logic tool, which provides a knowledge-based development environment to carry out the modeling of the signaling. The first one is a standard (forward) search. The second one is a novel approach based on narrowing, which allows us to trace backwards the causes of a given final state. The analysis allows the identification of critical elements that have to be activated to provoke proliferation.

ErbB Receptors and Cancer

The ErbB receptor family, also known as the EGF receptor family or type I receptor family, includes the epidermal growth factor (EGF) receptor (EGFR) or ErbB1/Her1, ErbB2/Her2, ErbB3/Her3, and ErbB4/Her4. Among all RTKs, EGFR was the first RTK identified and the first one linked to cancer. Thus, EGFR has also been the most intensively studied among all RTKs. ErbB receptors are activated after homodimerization or heterodimerization. The ErbB family is unique among the various groups of receptor tyrosine kinases (RTKs) in that ErbB3 has impaired kinase activity, while ErbB2 does not have a direct ligand. Therefore, heterodimerization is an important mechanism that allows the activation of all ErbB receptors in response to ligand stimulation. The activated ErbB receptors bind to many signaling proteins and stimulate the activation of many signaling pathways. The specificity and potency of intracellular signaling pathways are determined by positive and negative regulators, the specific composition of activating ligand(s), receptor dimer components, and the diverse range of proteins that associate with the tyrosine phosphorylated C-terminal domain of the ErbB receptors. ErbB receptors are overexpressed or mutated in many cancers, especially in breast cancer, ovarian cancer, and non-small cell lung cancer. The overexpression and overactivation of ErbB receptors are correlated with poor prognosis, drug resistance, cancer metastasis, and lower survival rate. ErbB receptors, especially EGFR and ErbB2 have been the primary choices as targets for developing cancer therapies.

Clustered localization of EGFRvIII in glioblastoma cells as detected by high precision localization microscopy

For receptor tyrosine kinases supramolecular organization on the cell membrane is critical for their function. Super-resolution fluorescence microscopy techniques have offered new opportunities for the analysis of single receptor localization. Here, we analysed the cluster formation of the epidermal growth factor receptor variant III (EGFRvIII), a deletion variant which is expressed in glioblastoma. The constitutively activated variant EGFRvIII is expressed in cells with an egfr gene amplification and is thought to enhance the tumorigenic potential especially of glioblastoma cells. Due to the lack of an adequate model system, it is still unclear how endogenous EGFRvIII expression alters cellular signalling and if it is organized in clusters like the wild type receptor. We have recently described the establishment of two pairs of iso-genetic cell lines (BS153 and DKMG), displaying endogenous EGFRvIII expression or not. Using these cell lines we investigated single receptor localization of EGFRvIII by high precision localization microscopy. Cluster analysis revealed that EGFRvIII is present in clusters on the surface of the cells, with about 60% or even more receptor molecules being assembled in clusters of approximately 100 nm in diameter whereby the cluster definition was iteratively determined. The signal to signal distance may indicate dimer formation while signal quantification indicates 1 × 10⁶-5 × 10⁶ EGFRvIII molecules per cell. Altogether, these data give unique insights into the membrane surface localization of EGFRvIII in glioblastoma cells. These insights will help to unveil the function of this tumour associated receptor variant which might lead to a better understanding of glioblastoma and therefore could lead to improved therapy approaches.

Efficient [(18)F]AlF Radiolabeling of ZHER3:8698 Affibody Molecule for Imaging of HER3 Positive Tumors

The human epidermal growth factor receptor 3 (HER3) is overexpressed in several cancers, being linked to a more resistant phenotype and hence leading to poor patient prognosis. Imaging HER3 is challenging owing to the modest receptor number (<50000 receptors/cell) in overexpressing cancer cells. Therefore, to image HER3 in vivo, high target affinity PET probes need to be developed. This work describes two different [(18)F]AlF radiolabeling strategies of the ZHER3:8698 affibody molecule specifically targeting HER3. The one-pot radiolabeling of ZHER3:8698 performed at 100 °C and using 1,4,7-triazanonane-1,4,7-triacetate (NOTA) as chelator resulted in radiolabeled products with variable purity attributed to radioconjugate thermolysis. An alternative approach based on the inverse electron demand Diels-Alder (IEDDA) reaction between a novel tetrazine functionalized 1,4,7-triazacyclononane-1,4-diacetate (NODA) chelator and the trans-cyclooctene (TCO) functionalized affibody molecule was also investigated. This method enabled the radiolabeling of the protein at room temperature. The [(18)F]AlF-NOTA-ZHER3:8698 and [(18)F]AlF-NODA-ZHER3:8698 conjugates showed a specific uptake at 1 h after injection in high HER3-expressing MCF-7 tumors of 4.36 ± 0.92% ID/g and 4.96 ± 0.65% ID/g, respectively. The current results are encouraging for further investigation of [(18)F]AlF-NOTA-ZHER3:8698 as a HER3 imaging agent.

MLK3 Signaling in Cancer Invasion

Mixed-lineage kinase 3 (MLK3) was first cloned in 1994; however, only in the past decade has MLK3 become recognized as a player in oncogenic signaling. MLK3 is a mitogen-activated protein kinase kinase kinase (MAP3K) that mediates signals from several cell surface receptors including receptor tyrosine kinases (RTKs), chemokine receptors, and cytokine receptors. Once activated, MLK3 transduces signals to multiple downstream pathways, primarily to c-Jun terminal kinase (JNK) MAPK, as well as to extracellular-signal-regulated kinase (ERK) MAPK, P38 MAPK, and NF-κB, resulting in both transcriptional and post-translational regulation of multiple effector proteins. In several types of cancer, MLK3 signaling is implicated in promoting cell proliferation, as well as driving cell migration, invasion and metastasis.

Profilings of MicroRNAs in the Liver of Common Carp (Cyprinus carpio) Infected with Flavobacterium columnare

MicroRNAs (miRNAs) play important roles in regulation of many biological processes in eukaryotes, including pathogen infection and host interactions. Flavobacterium columnare (FC) infection can cause great economic loss of common carp (Cyprinus carpio) which is one of the most important cultured fish in the world. However, miRNAs in response to FC infection in common carp has not been characterized. To identify specific miRNAs involved in common carp infected with FC, we performed microRNA sequencing using livers of common carp infected with and without FC. A total of 698 miRNAs were identified, including 142 which were identified and deposited in the miRbase database (Available online: http://www.mirbase.org/) and 556 had only predicted miRNAs. Among the deposited miRNAs, eight miRNAs were first identified in common carp. Thirty of the 698 miRNAs were differentially expressed miRNAs (DIE-miRNAs) between the FC infected and control samples. From the DIE-miRNAs, seven were selected randomly and their expression profiles were confirmed to be consistent with the microRNA sequencing results using RT-PCR and qRT-PCR. In addition, a total of 27,363 target genes of the 30 DIE-miRNAs were predicted. The target genes were enriched in five Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including focal adhesion, extracellular matrix (ECM)-receptor interaction, erythroblastic leukemia viral oncogene homolog (ErbB) signaling pathway, regulation of actin cytoskeleton, and adherent junction. The miRNA expression profile of the liver of common carp infected with FC will pave the way for the development of effective strategies to fight against FC infection.

An anti-HER2 antibody conjugated with monomethyl auristatin E is highly effective in HER2-positive human gastric cancer

Antibody-drug conjugate (ADC) is a novel class of therapeutics for cancer target therapy. This study assessed antitumor activity of ADC with an antimitotic agent, monomethyl auristatin E (MMAE) and a humanized monoclonal anti-HER2 antibody, hertuzumab, in gastric cancer. The efficacy of hertuzumab-MC-Val-Cit-PAB-MMAE (hertuzumab-vcMMAE) on human epidermal growth factor receptor 2 (HER2) positive human gastric cancer cells, NCI-N87, was evaluated in vitro and in vivo. The cytotoxicity of hertuzumab was significantly enhanced after conjugation with MMAE. Compared to trastuzumab, hertuzumab had a higher affinity to HER2 and had more potent antibody-dependent cell-mediated cytotoxicity (ADCC) activity in vitro. After conjugation with MMAE, the binding specificity for HER2 was not affected. Furthermore, the internalization of hertuzumab-vcMMAE in HER2 positive gastric cancer cells was verified. Although the conjugation of hertuzumab and MMAE decreased the ADCC effect, the overall cytotoxicity was dramatically increased in HER2 positive gastric cancer cells. In vitro data on this hertuzumab-vcMMAE has exerted much stronger antitumor activity compared to trastuzumab-DM1 in HER2 positive gastric cancer cells. A single administration of hertuzumab-vcMMAE at 5 or 10 mg/kg showed high potency and a sustained tumor inhibitory effect on NCI-N87 xenografts in mice. In conclusion, hertuzumab-vcMMAE conjugate is a highly effective anti-HER2 targeted therapy for HER2-positive gastric cancer.

Monoclonal Antibodies Approved for Cancer Therapy

Twenty-four monoclonal antibodies (mAbs) targeted to a total of 16 different antigens are currently approved for the treatment of an increasing number of cancers. Six are directed against antigens expressed on B lymphocytes (ibritumomab tiuxetan, obinutuzumab, ofatumumab, and rituximab to CD20, brentuximab vedotin to CD30, and alemtuzumab to CD52); cetuximab, panitumumab, and necitumumab target EGFR; bevacizumab and ramucirumab are specific for VEGF and VEGFR2, respectively; pertuzumab, trastuzumab, and ado-trastuzumab target HER2; nivolumab and pembrolizumab are directed to the programmed cell death protein 1 (PD-1); and denosumab, ipilimumab, siltuximab, and dinutuximab recognize RANKL, CTLA-4, IL-6, and the disialoganglioside (GD2), respectively. In November 2015, the FDA approved daratumumab, the first anti-CD38 mAb and the first mAb to be approved for the treatment of multiple myeloma. Elotuzumab, targeted to the receptor SLAMF7, was also given approval for multiple myeloma soon after. Two antibodies are bispecific: the rat-mouse chimera, catumaxomab, recognizes both EpCAM and CD3, while blinatumomab, a bispecific T-cell-engaging (BiTE) fusion protein, targets both CD19 and CD3. Although mAbs used for cancer immunotherapy are generally better tolerated than small molecule chemotherapeutic drugs, their range of adverse effects is still wide and varied from mild gastrointestinal symptoms and transient rashes to severe cytopenias; anaphylaxis; autoimmunity; pulmonary, cardiac, hepatic, kidney, neurological, and embryofetal toxicities; and rare life-threatening toxidermias. Because of their immunogenic potential, mAbs generally carry warnings of immune reactions, especially anaphylaxis, but the observed incidences of such reactions are actually quite small. Cytopenias occur in some patients treated with mAbs during anticancer immunotherapy, but the underlying mechanisms frequently remain unexplored. Type II and III hypersensitivities induced by mAbs may be underdiagnosed. Severe infusion reactions have been reported for all the mAbs although some show a much higher incidence with the chimeric rituximab and humanized trastuzumab antibodies being the leading offenders. Distinguishing features in the literature between cytokine release syndrome and severe infusion reactions are often not clear. At least ten of the currently approved mAbs for cancer therapy show some pulmonary toxicity. These pulmonary adverse events can be grouped into four categories: interstitial pneumonitis and fibrosis, acute respiratory distress syndrome (ARDS), bronchiolitis obliterans organizing pneumonia (BOOP), and hypersensitivity pneumonitis. Cardiac adverse events, including congestive heart failure, decreased LVEF, myocardial infarction, cardiac arrest, and arrhythmias, have occurred with at least 11 of the mAbs. Papulopustular eruptions, cutaneous reactions that are not immune-mediated, as well as a range of other adverse mucocutaneous effects, are elicited in a large proportion of patients by mAbs targeted to EGFR. Other rare but mAb-induced serious adverse events are tumor lysis syndrome and progressive multifocal leukoencephalopathy.

An Apoferritin-based Drug Delivery System for the Tyrosine Kinase Inhibitor Gefitinib

Anticancer drug Gefitinib encapsulated within human heavy chain apoferritin by diffusion allows pH-controlled sustained release of cargo. The combination of increased cellular uptake, and potent and enhanced antitumor activity against the HER2 overexpressing SKBR3 cell line compared to Gefitinib alone, makes it a promising carrier for delivery of drugs to tumor sites.

EGFR/MDM2 signaling promotes NF-κB activation via PPARγ degradation

Dysregulated expression of epidermal growth factor receptor (EGFR) has been implicated in many cancer events, while peroxisome proliferator-activated receptor γ (PPARγ) negatively regulates cancer progression. The molecular mechanism of EGFR interaction with PPARγ is still unclear. Here, we found that nuclear EGFR induced phosphorylation of PPARγ at Tyr-74 leading to PPARγ ubiquitination and degradation by mouse double minute 2 (MDM2) ubiquitin ligase. PPARγ degradation by EGFR/MDM2 signaling resulted in accumulation of nuclear factor-kappaB (NF-κB)/p65 protein levels and increasing NF-κB activation. In contrast, PPARγ-Y74A mutant reversed this event. Moreover, PPARγ-Y74A mutant suppressed cell proliferation and increased chemotherapeutic agent-induced cancer cell sensitivity. Importantly, the clinical findings show that the nuclear phosphorylation of PPARγ-Y74 and EGFR expression in colonic cancer tissues was higher than that in control normal tissues. Thus, our study revealed a novel molecular mechanism that nuclear EGFR/NF-κB signaling promoted cell proliferation by destructing PPARγ function, which provides a novel strategy for cancer treatment.

MiR-331-3p inhibits proliferation and promotes apoptosis by targeting HER2 through the PI3K/Akt and ERK1/2 pathways in colorectal cancer

MicroRNAs (miRNAs) regulate cell proliferation, apoptosis and carcinogenesis by targeting related mRNAs in different types of cancer. miR-331-3p has been found to regulate the development and progression of various types of cancer cells. However, little research has been conducted on the role of miR-331-3p in colorectal cancer (CRC). The present study aimed to explore the function of miR-331-3p in CRC. We found that miR-331-3p was significantly downregulated in CRC tissues and cells compared to the level in healthy colon tissues and cells. Overexpression of miR-331-3p by transfection with pre‑miR-331-3p inhibited cell proliferation, promoted apoptosis and activated caspase-3. Furthermore, the protein expression level of apoptosis-related protein Bcl-2 was downregulated and Bax was upregulated by pre‑miR‑331-3p. Downregulation of the expression of miR-331-3p by transfection with AS-miR-331-3p had the opposite effect. Moreover, we found that HER2 was overexpressed in the CRC cell lines, and the expression level of HER2 was negatively regulated by miR‑331-3p. Additionally, knockdown of HER2 inhibited cell proliferation and phosphorylation of Akt and ERK1/2 induced by AS-miR-331-3p. Overall, we identified that miR‑331-3p is underexpressed in CRC and contributes to cell growth regulation by targeting HER2 through activating the PI3K/Akt and ERK1/2 signaling pathways.

Platelet Derived Growth Factor-B and Human Epidermal Growth Factor Receptor-2 Polymorphisms in Gall Bladder Cancer

Gall bladder cancer (GBC) is a gastro-intestinal cancer with high prevalence among north Indian women. Platelet derived growth factor-B (PDGFB) and human epidermal growth factor receptor-2 (HER2) may play roles in the etiology of GBC through the inflammation-hyperplasia-dysplasia-carcinoma pathway. To study the association of PDGFB and HER2 polymorphisms with risk of GBC, 200 cases and 300 controls were considered. PDGFB +286A>G and +1135A>C polymorphisms were investigated with an amplification refractory mutation system and the HER2 Ile655Val polymorphism by restriction fragment length polymorphism. Significant risk associations for PDGFB +286 GG (OR=5.25) and PDGFB +1135 CC (OR=3.19) genotypes were observed for GBC. Gender wise stratification revealed susceptibility for recessive models of PDGFB +1135A>C (OR=3.00) and HER2 Ile655Val (OR=2.52) polymorphisms among female GBC cases. GBC cases with gall stones were predisposed to homozygous +286 GG and +1135 CC genotypes. Significant risk associations were found for ACIle (OR=1.48), GAVal (OR=1.70), GAIle (OR=2.00) haplotypes with GBC cases and GCIle haplotype with female GBC cases (OR=10.37, P=<0.0001). Pair-wise linkage disequilibrium revealed negative associations among variant alleles. On multi-dimensional reduction analysis, a three factor model revealed significant gene-gene interaction for PDGFB +286A>G, PDGFB +1135A>C and HER2 Ile165Val SNPs with GBC. Protein-protein interaction showed significant association of PDGFB and HER2 with the epidermal growth factor receptor signaling pathway.

Role of HER family members in predicting prognoses in epithelial ovarian cancer: a meta-analysis

AIMS AND BACKGROUND

Human epidermal receptor (HER) family receptors are commonly overexpressed in various human tumors, and their overexpression is thought to play a critical role in tumor progression. The aim of this meta-analysis was to evaluate the prognostic significance of HER family members in epithelial ovarian cancer (EOC).

METHODS

Relevant studies published between January 1, 1980, and April 24, 2013, that evaluated the associations of HER family members with overall survival (OS), progression-free survival (PFS), response to platinum-based chemotherapy, lymph node metastasis, or ascites in EOC were identified via searches of PubMed and EMBASE.

RESULTS

We identified 37 eligible articles that met the inclusion criteria. The results of the meta-analysis revealed that significantly poorer OS of patients with EOC was predicted by high Her-2 expression levels (hazard ratio [HR] 1.69, 95% confidence interval [CI] 1.31-2.19). Furthermore, high Her-2 expression was significantly associated with poor PFS (HR 1.88, 95% CI 1.46-2.41) and an increased risk of ascites (risk ratio 1.21, 95% CI 1.02-1.42).

CONCLUSIONS

High levels of expression of Her-2 are significantly related to poor survival and an increased risk of ascites in patients with EOC. Future prospective cohorts with larger samples are needed to verify the prognostic value of Her-2 expression in EOC.

Expression and Characterization of the Extracellular Domain of Human HER2 from Escherichia Coli, and Production of Polyclonal Antibodies Against the Recombinant Proteins

Human epidermal growth factor receptor 2 (HER2) is a member of the epidermal growth factor receptor (EGFR) family. In this study, the whole extracellular domain gene of HER2 was amplified by RT-PCR from human breast cancer cell line SK-BR-3. The genes of membrane-distal region (A) and membrane proximal region (B) of HER2 extracellular domain were amplified from the cloned template, and then inserted into the expression vector pET-28a and pET-30a, respectively. The recombinant expression vectors were transformed into Escherichia coli BL21 (DE3) cells and induced by isopropyl-b-D-thiogalactopyranoside (IPTG) for expression of proteins His-A and His-B. The expressed proteins were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blot. The optimization of culture conditions led us to accomplish the recombinant protein induction with 1.0 mM IPTG at 37 °C for 8 h, and both proteins were expressed in the insoluble form. Both proteins were purified under the denaturing condition using Ni-NTA sepharose column. Balb/c mice were immunized with the purified proteins and then effectively produced polyclonal antibodies, which reached to a relatively high titer by ELISA testing and had good specificity by western blot detection. The HER2 ECD proteins His-A and His-B could be expressed in E. coli and were suitable for production of high titer antibodies against HER2 ECD.

Investigation of gene effects and epistatic interactions between Akt1 and neuregulin 1 in the regulation of behavioral phenotypes and social functions in genetic mouse models of schizophrenia

Accumulating evidence from human genetic studies has suggested several functional candidate genes that might contribute to susceptibility to schizophrenia, including AKT1 and neuregulin 1 (NRG1). Recent findings also revealed that NRG1 stimulates the PI3-kinase/AKT signaling pathway, which might be involved in the functional outcomes of some schizophrenic patients. The aim of this study was to evaluate the effect of Akt1-deficiency and Nrg1-deficiency alone or in combination in the regulation of behavioral phenotypes, cognition, and social functions using genetically modified mice as a model. Male Akt1^+/−, Nrg1^+/−, and double mutant mice were bred and compared with their wild-type (WT) littermate controls. In Experiment 1, general physical examination revealed that all mutant mice displayed a normal profile of body weight during development and a normal brain activity with microPET scan. In Experiment 2, no significant genotypic differences were found in our basic behavioral phenotyping, including locomotion, anxiety-like behavior, and sensorimotor gating function. However, both Nrg1^+/− and double mutant mice exhibited impaired episodic-like memory. Double mutant mice also had impaired sociability. In Experiment 3, a synergistic epistasis between Akt1 and Nrg1 was further confirmed in double mutant mice in that they had impaired social interaction compared to the other 3 groups, especially encountering with a novel male or an ovariectomized female. Double mutant and Nrg1^+/− mice also emitted fewer female urine-induced ultrasonic vocalization calls. Collectively, our results indicate that double deficiency of Akt1 and Nrg1 can result in the impairment of social cognitive functions, which might be pertinent to the pathogenesis of schizophrenia-related social cognition.

Fluorogen activating protein-affibody probes: modular, no-wash measurement of epidermal growth factor receptors

Fluorescence is essential for dynamic live cell imaging, and affinity reagents are required for quantification of endogenous proteins. Various fluorescent dyes can report on different aspects of biological trafficking, but must be independently conjugated to affinity reagents and characterized for specific biological readouts. Here we present the characterization of a new modular platform for small anti-EGFR affinity probes for studying rapid changes in receptor pools. A protein domain (FAP _dL5**) that binds to malachite-green (MG) derivatives for fluorescence activation was expressed as a recombinant fusion to one or two copies of the compact EGFR binding affibody Z_EGFR:1907. This is a recombinant and fluorogenic labeling reagent for native EGFR molecules. In vitro fluorescence assays demonstrated that the binding of these dyes to the FAP–affibody fusions produced thousand-fold fluorescence enhancements, with high binding affinity and fast association rates. Flow cytometry assays and fluorescence microscopy demonstrated that these probes label endogenous EGFR on A431 cells without disruption of EGFR function, and low nanomolar surface K_d values were observed with the double-Z_EGFR:1907 constructs. The application of light-harvesting fluorogens (dyedrons) significantly improved the detected fluorescence signal. Altering the order of addition of the ligand, probe, and dyes allowed differentiation between surface and endocytotic pools of receptors to reveal the rapid dynamics of endocytic trafficking. Therefore, FAP/affibody coupling provides a new approach to construct compact and modular affinity probes that label endogenous proteins on living cells and can be used for studying rapid changes in receptor pools involved in trafficking.

Expression of MHC Class I on breast cancer cells correlates inversely with HER2 expression

HER2 is a promising target for immunotherapeutic interventions with T cell-based approaches since it is amplified and overexpressed in 20–30% of breast cancers. However, several previous studies including ours showed that HER2-overexpressing tumors may escape cytotoxic T lymphocyte-mediated lysis by downregulating MHC Class I and components of the antigen-processing machinery. The aims of the present study were to analyze the relationship between HER2 and MHC Class I expression and to elucidate the mechanisms underlying MHC Class I downregulation in breast cancer. We explored expression of HER2, MHC Class I, PTEN, Ki67, estrogen and progesterone expression in 70 breast cancer patients by immunohistochemistry (IHC) and analyzed their correlation. We also explored the components of the signal transduction pathway that are involved in the regulation of MHC Class I expression using small-interfering RNAs targeting HER2 as well as an inhibitor of HER2 signaling. HER2 expression in breast cancers correlated inversely with MHC Class I expression analyzed by IHC. HER2 depletion by small-interfering RNAs resulted in MHC Class I upregulation. Moreover, MHC Class I expression on breast cancer cell lines was upregulated by PD98059, an inhibitor of mitogen-associated protein kinases, in a dose-dependent manner. Thus, agents that target the MAPK signaling pathway may increase MHC Class I expression in breast cancer cells.

Ligand-independent epidermal growth factor receptor hyperactivation increases sebaceous gland size and sebum secretion in mice

The epidermal growth factor receptor (EGFR) system is an established regulator of the development and homeostasis of the hair follicle and interfollicular epidermis. Here, we evaluated EGFR actions on the sebaceous glands (SGs) by employing Dsk5 mice, a mutant line in which the EGFR is constitutively activated in a ligand-independent manner. Compared to control littermates, Dsk5 mice showed increased sebum levels and enlarged SGs, which contained a higher number of cells and showed stronger proliferation. c-myc transcript levels were increased in Dsk5 skin, suggesting that c-myc mediates the proliferative stimuli of the EGFR in the SG. Analysis of differentiation markers revealed deregulated expression of Scd1 and Scd3, indicating that sebaceous lipogenesis is affected in Dsk5 mice. In conclusion, our study indicates that the EGFR is an important regulator of presebocyte proliferation, contributing to the final cell number, to the size and to the lipid output of SGs.

In vitro combined treatment with cetuximab and trastuzumab inhibits growth of colon cancer cells

OBJECTIVES

Overexpression or constitutive activation of epidermal growth factor receptors (EGFR) is involved in growth of human cancers. We investigated effects of EGFR and HER-2 blockade in colon cancer cell lines using cetuximab and trastuzumab, with the aim of developing novel approaches to cancer therapy.

MATERIALS AND METHODS

We studied effects of treatment on cell growth, cell cycle distribution, induction of apoptosis, changes in EGFR and HER-2 mRNA-protein expression and EGFR and HER-2 gene copy number in Caco-2, HT-29 and HCT-116 cells.

RESULTS

Treatment of cells resulted in no effect in one of the three cell lines and in inhibition of cell proliferation in a time- and dose-dependent manner in the other two, with modulation of EGFR and HER-2 mRNA and protein levels. Differences in sensitivity to cetuximab and trastuzumab were observed. Treatment induced specific changes in cell cycle distribution in both cell lines affected, while apoptosis was not increased. Fluorescence in situ hybridization analysis revealed abnormal copy number of two genes resulting from aneuploidy; this was not responsible for different sensitivity to combination between the two cell lines.

CONCLUSIONS

Targeting EGFR and HER-2 simultaneously could have useful applications in colorectal cancer treatment. To improve pharmacological efficacy of cetuximab and trastuzumab combination, molecular mechanisms involved in their activity need to be elucidated.

Whole genome DNA methylation signature of HER2-positive breast cancer

In order to obtain a comprehensive DNA methylation signature of HER2-positive breast cancer (HER2+ breast cancer), we performed a genome-wide methylation analysis on 17 HER2+ breast cancer and compared with ten normal breast tissue samples using the Illumina Infinium HumanMethylation450 BeadChip (450K). In HER2+ breast cancer, we found altered DNA methylation in genes involved in multicellular development, differentiation and transcription. Within these genes, we observed an overrepresentation of homeobox family genes, including several genes that have not been previously reported in relation to cancer (DBX1, NKX2-6, SIX6). Other affected genes included several belonging to the PI3K and Wnt signaling pathways. Notably, HER2, AKT3, HK1, and PFKP, genes for which altered methylation has not been previously reported, were also identified in this analysis. In total, we report 69 candidate biomarker genes with maximum differential methylation in HER2+ breast cancer. External validation of gene expression in a selected group of these genes (n = 13) revealed lowered mean gene expression in HER2+ breast cancer. We analyzed DNA methylation in six top candidate genes (AKR1B1, INA, FOXC2, NEUROD1, CDKL2, IRF4) using EpiTect Methyl II Custom PCR Array and confirmed the 450K array findings. Future clinical studies focusing on these genes, as well as on homeobox-containing genes and HER2, AKT3, HK1, and PFKP, are warranted which could provide further insights into the biology of HER2+ breast cancer.

Expression of the EGF family in gastric cancer: downregulation of HER4 and its activating ligand NRG4

Gastric cancer is a major cause of cancer-related deaths in both men and women. The epidermal growth factor receptors are EGFR, HER2, HER3 and HER4. Of the four epidermal growth factor receptors, EGFR and HER2 are well-known oncogenes involved in gastric cancer. Little, however, is known about the role played by HER3 and HER4 in this disease. We obtained paired samples from the tumor and the adjacent normal tissue from the same patient undergoing surgery for gastric cancer. Using RT-qPCR, we quantified the mRNA expression of the four receptors including the HER4 splicing isoforms and all the ligands activating these receptors. Using immunohistochemistry, the protein expression of HER4 was also quantified. We found that HER2 mRNA expression was upregulated in the tumor tissue compared to the matched normal tissue (p = 0.0520). All ligands with affinity for EGFR were upregulated, whereas the expression of EGFR was unchanged. Interestingly, we found the mRNA expression of HER4 (p = 0.0002) and its ligand NRG4 (p = 0.0009) to be downregulated in the tumor tissue compared to the matched normal tissue. HER4 downregulation was demonstrated for all the alternatively spliced isoforms of this receptor. These results support the involvement of EGFR and HER2 in gastric cancer and suggest an interesting association of reduced HER4 expression with development of gastric cancer.

Imaging of HER3-expressing xenografts in mice using a (99m)Tc(CO) 3-HEHEHE-Z HER3:08699 affibody molecule

PURPOSE

Human epidermal growth factor receptor type 3 (HER3) is a transmembrane receptor tyrosine kinase belonging to the HER (ErbB) receptor family. Membranous expression of HER3 is associated with trastuzumab resistance in breast cancer and the transition to androgen independence in prostate cancer. Imaging of HER3 expression in malignant tumors may provide important diagnostic information that can influence patient management. Affibody molecules with low picomolar affinity to HER3 were recently selected. The aim of this study was to investigate the feasibility of HER3 imaging using radiolabeled Affibody molecules.

METHODS

A HER3-binding Affibody molecule, Z08699, with a HEHEHE-tag on N-terminus was labeled with (99m)Tc(CO)3 using an IsoLink kit. In vitro and in vivo binding specificity and the cellular processing of the labeled binder were evaluated. Biodistribution of (99m)Tc(CO)3-HEHEHE-Z08699 was studied over time in mice bearing HER3-expressing xenografts.

RESULTS

HEHEHE-Z08699 was labeled with (99m)Tc(CO)3 with an isolated yield of >80 % and a purity of >99 %. Binding of (99m)Tc(CO)3-HEHEHE-Z08699 was specific to BT474 and MCF7 (breast cancer), and LS174T (colon cancer) cells. Cellular processing showed rapid binding and relatively quick internalization of the receptor/Affibody molecule complex (70 % of cell-associated radioactivity was internalized after 24 h). The tumor targeting was receptor mediated and the excretion was predominantly renal. Receptor-mediated uptake was also found in the liver, lung, stomach, intestine, and salivary glands. At 4 h pi, tumor-to-blood ratios were 7 ± 3 for BT474, and 6 ± 2 for LS174T xenografts. LS174T tumors were visualized by microSPECT 4 h pi.

CONCLUSIONS

The results of this study suggest the feasibility of HER3-imaging in malignant tumors using Affibody molecules.

Strong dimerization of wild-type ErbB2/Neu transmembrane domain and the oncogenic Val664Glu mutant in mammalian plasma membranes

Here, we study the homodimerization of the transmembrane domain of Neu, as well as an oncogenic mutant (V664E), in vesicles derived from the plasma membrane of mammalian cells. For the characterization, we use a Förster resonance energy transfer (FRET)-based method termed Quantitative Imaging-FRET (QI-FRET), which yields the donor and acceptor concentrations in addition to the FRET efficiencies in individual plasma membrane-derived vesicles. Our results demonstrate that both the wild-type and the mutant are 100% dimeric, suggesting that the Neu TM helix dimerizes more efficiently than other RTK TM domains in mammalian membranes. Furthermore, the data suggest that the V664E mutation causes a very small, but statistically significant change in dimer structure. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova.

Building bridges toward invasion: tumor promoter treatment induces a novel protein kinase C-dependent phenotype in MCF10A mammary cell acini

The potent tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) alters many cellular processes through activation of its receptor protein kinase C (PKC), including gene expression, cell cycle, and the regulation of cell morphology, raising an important question for developing targeted methods to prevent cancer: which effects of TPA are crucial for carcinogenesis? To address this question, we studied TPA action in the 3-dimensional (3D) MCF10A human breast epithelial cell system, which models important features of in vivo epithelial tissue including growth constraints, structural organization of cells, and establishment of a basement membrane. MCF10A cells, which are immortalized but nontumorigenic, form hollow, spheroid structures in 3D culture referred to as acini. The development of normal acini requires the tight spatiotemporal regulation of cellular proliferation, polarization, apoptosis, and growth arrest. Treatment of MCF10A acini with TPA caused the appearance of multi-acinar structures. Surprisingly, this phenotype did not involve an increase in cell number or major changes in cell death, and polarization. Instead, live cell and confocal microscopy revealed that TPA stimulates MCF10A acini to aggregate. TPA induces the PKC-dependent production of actin-based protrusions, which leads to the formation of cellular bridges between acini, the clustering of acini, and allows cells to move into adjacent acini. During this process, the integrity of the laminin V basement membrane is disrupted, while E-cadherin-based cell-cell contacts remain intact. Altogether, our results show that under the biochemical and structural constraints of epithelial tissue, as modeled by the 3D MCF10A system, TPA induces a novel PKC-dependent phenotype that resembles local invasion. Of the many effects caused by TPA, these studies highlight the aggressive production of actin-based cellular protrusions as a potentially important event along the pathway to carcinogenesis.

Hepatitis B virus X upregulates HuR protein level to stabilize HER2 expression in hepatocellular carcinoma cells

Hepatitis B virus- (HBV-) associated hepatocellular carcinoma (HCC) is the most common type of liver cancer. However, the underlying mechanism of HCC tumorigenesis is very complicated and HBV-encoded X protein (HBx) has been reported to play the most important role in this process. Activation of downstream signal pathways of epidermal growth factor receptor (EGFR) family is known to mediate HBx-dependent HCC tumor progression. Interestingly, HER2 (also known as ErbB2/Neu/EGFR2) is frequently overexpressed in HBx-expressing HCC patients and is associated with their poor prognosis. However, it remains unclear whether and how HBx regulates HER2 expression. In this study, our data showed that HBx expression increased HER2 protein level via enhancing its mRNA stability. The induction of RNA-binding protein HuR expression by HBx mediated the HER2 mRNA stabilization. Finally, the upregulated HER2 expression promoted the migration ability of HBx-expressing HCC cells. These findings deciphered the molecular mechanism of HBx-mediated HER2 upregulation in HBV-associated HCC.

Survivin and pAkt as potential prognostic markers in squamous cell carcinoma of the head and neck

OBJECTIVE

The purpose of our study was to investigate the expression patterns of cell cycle regulatory proteins and members of the epidermal growth factor receptor (EGFR) signaling pathway in squamous cell carcinoma of the head and neck (HNSCC).

STUDY DESIGN

The expression levels of survivin, Bub1 B (budding uninhibited by benzimidazoles 1 homolog beta), PLK-1 (polo-like kinase 1), Ki-67, cyclin D1, p53, EGFR, pMAPK (phosphorylated mitogen-activated protein kinase), pAkt (phosphorylated protein kinase B), and PTEN (phosphatase and tensin homolog) were studied in a series of 180 tumor samples obtained from HNSCC surgical resections, 50 metastatic lymph node samples, and 72 corresponding noncancerous epithelium samples. Protein expression analysis was performed by immunohistochemical staining. The results were correlated with clinicopathologic features and survival data.

RESULTS

Prognostic significance could be found only for the markers survivin and pAkt. Only the marker combination of cyclin D1 and p53 had positive prognosis potential regarding overall survival.

CONCLUSIONS

Both pAkt and survivin show a positive correlation with distant metastases and may have utility as predictors of long-term outcomes for patients with HNSCC.

EGF RECEPTOR DYNAMICS IN EGF-RESPONDING CELLS REVEALED BY FUNCTIONAL IMAGING DURING SINGLE PARTICLE TRACKING

The epidermal growth factor (EGF) receptor transduces the extracellular EGF signal into the cells. The distribution of these EGF receptors in the plasma membrane is heterogeneous and dynamic, which is proposed to be important for the regulation of cell signaling. The response of the cells to a physiological concentration of EGF is not homogeneous, which makes it difficult to analyze the dynamics related to the response. Here we developed a system to perform functional imaging during single particle tracking (SPT) analysis. This system made it possible to observe the cytosolic Ca 2+ concentration to monitor the cell response while tracking individual EGF molecules and found that about half of the cells responded to the stimulation with 1.6 nM EGF. In the responding cells, the EGF receptor showed 3 modes of movement: fast (the diffusion coefficient of 0.081 ± 0.009 μm2/sec, 29 ± 9%), slow (0.020 ± 0.005 μm2/sec, 22 ± 6%), and stationary (49 ± 13%). The diffusion coefficient of the fast mode movement in the responding cells was significantly larger than that in the nonresponding cells (0.069 ± 0.009 μm2/sec, p < 0.05). The diffusion coefficient of the fast mode movement is thought to reflect the monomer–dimer equilibrium of the EGF receptor. We assumed that the feedback regulation via the Ca 2+ signaling pathway slightly shifts the equilibrium from dimer to monomer in the responding cells.

[Formula: see text]Special Issue Comment: This research paper is about the diffusion of EGF receptors in the membrane. It is therefore related with various projects in this Special Issue: the reviews about FRET41 and enzymes,42 and the projects about solving single molecules trajectories.43

The MAPK pathway is a predominant regulator of HLA-A expression in esophageal and gastric cancer

Downregulation of HLA class I expression may contribute to a poor prognosis in cancer patients. There is limited information about epigenetic and oncogenic regulation of HLA class I, and multiple mechanisms may be involved. In the current study, we examined the relationship between the HER2-signaling pathway (MAPK and PI3K-Akt) and the expression of HLA class I and Ag-processing machinery (APM) components. A panel of gastric and esophageal cancer cell lines was treated with wortmannin as an Akt-signal inhibitor; the MAPK signal inhibitor PD98059; lapatinib, which inhibits both the epidermal growth factor receptor and HER2 tyrosine kinase; or siRNA for MAPK. The levels of HER2-signaling molecules, APM components, and HLA class I were evaluated by Western blot, quantitative PCR, and flow cytometry. Resected gastric tumor tissues (n = 102) were analyzed for p-Erk and HLA class I expression by immunohistochemistry. As a result, inhibition of the MAPK pathway induced upregulation of HLA-A02 and HLA-A24 expression in parallel with an increase in APM components and enhanced target sensitivity to tumor Ag-specific CTL lysis. HLA-A expression was predominantly regulated by the MAPK pathway, but it was also influenced, in part, by the Akt pathway. There was a strong inverse correlation between p-Erk expression and HLA class I expression in clinical tumor samples. In conclusion, HLA-A expression is predominantly regulated by the MAPK pathway in gastric and esophageal cancer.

Effect of acute acid-base disturbances on ErbB1/2 tyrosine phosphorylation in rabbit renal proximal tubules

The renal proximal tubule (PT) is a major site for maintaining whole body pH homeostasis and is responsible for reabsorbing ∼80% of filtered HCO3(-), the major plasma buffer, into the blood. The PT adapts its rate of HCO3(-) reabsorption (JHCO3(-)) in response to acute acid-base disturbances. Our laboratory previously showed that single isolated perfused PTs adapt JHCO3(-) in response to isolated changes in basolateral (i.e., blood side) CO2 and HCO3(-) concentrations but, surprisingly, not to pH. The response to CO2 concentration can be blocked by the ErbB family tyrosine kinase inhibitor PD-168393. In the present study, we exposed enriched rabbit PT suspensions to five acute acid-base disturbances for 5 and 20 min using a panel of phosphotyrosine (pY)-specific antibodies to determine the influence of each disturbance on pan-pY, ErbB1-specific pY (four sites), and ErbB2-specific pY (two sites). We found that each acid-base treatment generated a distinct temporal pY pattern. For example, the summated responses of the individual ErbB1/2-pY sites to each disturbance showed that metabolic acidosis (normal CO2 concentration and reduced HCO3(-) concentration) produced a transient summated pY decrease (5 vs. 20 min), whereas metabolic alkalosis produced a transient increase. Respiratory acidosis (normal HCO3(-) concentration and elevated CO2 concentration) had little effect on summated pY at 5 min but produced an elevation at 20 min, whereas respiratory alkalosis produced a reduction at 20 min. Our data show that ErbB1 and ErbB2 in the PT respond to acute acid-base disturbances, consistent with the hypothesis that they are part of the signaling cascade.

Feasibility study of brain tumor delineation using immunolabeled gold nanorods

Effective treatment of patients with malignant brain tumors requires surgical resection of a high percentage of the bulk tumor. Surgeons require a method that enables delineation of tumor margins, which are not visually distinct by eye. In this study, the feasibility of using gold nanorods (GNRs) for this purpose is evaluated. Anti-Epidermal Growth Factor Receptor (anti-EGFR) conjugated GNRs are used to label human xenograft glioblastoma multiforme (GBM) tumors embedded within slices of brain tissues from healthy nude mice. The anti-EGFR GNRs exhibit enhanced absorption at red to near-infrared wavelengths, often referred to as the tissue optical window, where absorption from blood is minimal. To enable definition of molecular specificity and spatial accuracy of the label, the GNR absorption is compared with GFP fluorescence which is expressed by the GBM cells used here. This work demonstrates a simple but highly translational technique to classify normal and malignant brain tissue regions in open surgery applications using immunolabeled GNR contrast agents.

The two sides of HER2/neu: immune escape versus surveillance

The oncogene HER2 is one of the prototypes for targeted immunotherapy of cancer using both monoclonal antibodies as well as T cell based immunotherapies. Effective humoral and cellular immune responses against HER2 can be induced, but these responses can be influenced by the effects of this oncogene on the target tumor cells. The processes involved in HER2-mediated adaptive and innate immunity and the molecular mechanisms underlying the escape of HER2-expressing tumor cells from immune surveillance, particularly from cytotoxic T cells, are discussed. Implementing this knowledge in clinical trials to revert immune evasion may help optimize immunotherapies directed against HER2-expressing tumors.

Expression levels and significance of nuclear factor-κB and epidermal growth factor receptor in hepatolithiasis associated with intrahepatic cholangiocarcinoma

BACKGROUND

An increasing incidence of cholangiocarcinoma (CCA) and CCA mortality rates has been observed around the world. Patients with intrahepatic biliary stones have a 10% risk of developing CCA, and up to 70% of patients with histologically confirmed CCA have hepatolithiasis. Few previous studies have addressed the associations between the expression of nuclear factor (NF)-κB and epidermal growth factor receptor (EGFR) and clinicopathological prognosis in patients with hepatolithiasis-associated intrahepatic CCA.

AIMS

This study was designed to investigate the clinicopathological and prognostic significance of NF-κB and EGFR expression in hepatolithiasis-associated intrahepatic CCA and hepatolithiasis.

METHODS

A total of 90 liver specimens were immunohistochemically stained for NF-κB and EGFR expression, and the characteristics of 90 individual patients were retrospectively reviewed.

RESULTS

Differences in the positive rates of NF-κB and EGFR expression between the hepatolithiasis-associated intrahepatic CCA group, intrahepatic lithiasis group, and control group were found to be statistically significant. EGFR expression was closely associated with the degree of differentiation and depth of invasion (p < 0.05). The 1-, 3-, and 5-year overall survival rates were respectively 42.8, 21.0, and 10.3% in intrahepatic CCA groups. The survival rate of the EGFR-negative group was higher than in the EGFR-positive group (p < 0.01). Lymph node metastasis (HR 1.24, 95% CI 1.02-1.51) and EGFR positivity (HR 1.74, 95% CI 1.30-2.23) were associated with decreases in the survival rate.

CONCLUSION

The expression of NF-κB may be an early step in intrahepatic cholangiocarcinogenesis. Overexpression of EGFR is associated with the degree of malignancy and with poor prognosis. NF-κB and EGFR may cooperate during intrahepatic cholangiocarcinogenesis and progression. Lymph node metastasis and EGFR positivity were associated with decreases in the survival rate.

Personalizing colon cancer therapeutics: targeting old and new mechanisms of action

The use of pharmaceuticals for colon cancer treatment has been increasingly personalized, in part due to the development of new molecular tools. In this review, we discuss the old and new colon cancer chemotherapeutics, and the parameters that have been shown to be predictive of efficacy and safety of these chemotherapeutics. In addition, we discuss how alternate pharmaceuticals have been developed in light of a potential lack of response or resistance to a particular chemotherapeutic.

Receptor tyrosine kinases fall into distinct classes based on their inferred signaling networks

Although many anticancer drugs that target receptor tyrosine kinases (RTKs) provide clinical benefit, their long-term use is limited by resistance that is often attributed to increased abundance or activation of another RTK that compensates for the inhibited receptor. To uncover common and unique features in the signaling networks of RTKs, we measured time-dependent signaling in six isogenic cell lines, each expressing a different RTK as downstream proteins were systematically perturbed by RNA interference. Network models inferred from the data revealed a conserved set of signaling pathways and RTK-specific features that grouped the RTKs into three distinct classes: (i) an EGFR/FGFR1/c-Met class constituting epidermal growth factor receptor, fibroblast growth factor receptor 1, and the hepatocyte growth factor receptor c-Met; (ii) an IGF-1R/NTRK2 class constituting insulin-like growth factor 1 receptor and neurotrophic tyrosine receptor kinase 2; and (iii) a PDGFRβ class constituting platelet-derived growth factor receptor β. Analysis of cancer cell line data showed that many RTKs of the same class were coexpressed and that increased abundance of an RTK or its cognate ligand frequently correlated with resistance to a drug targeting another RTK of the same class. In contrast, abundance of an RTK or ligand of one class generally did not affect sensitivity to a drug targeting an RTK of a different class. Thus, classifying RTKs by their inferred networks and then therapeutically targeting multiple receptors within a class may delay or prevent the onset of resistance.

Nuclear EGFR as a molecular target in cancer

The epidermal growth factor receptor (EGFR) has been one of the most targeted receptors in the field of oncology. While anti-EGFR inhibitors have demonstrated clinical success in specific cancers, most patients demonstrate either intrinsic or acquired resistance within one year of treatment. Many mechanisms of resistance to EGFR inhibitors have been identified, one of these being attributed to alternatively localized EGFR from the cell membrane into the cell's nucleus. Inside the nucleus, EGFR functions as a co-transcription factor for several genes involved in cell proliferation and angiogenesis, and as a tyrosine kinase to activate and stabilize proliferating cell nuclear antigen and DNA dependent protein kinase. Nuclear localized EGFR is highly associated with disease progression, worse overall survival in numerous cancers, and enhanced resistance to radiation, chemotherapy, and the anti-EGFR therapies gefitinib and cetuximab. In this review the current knowledge of how nuclear EGFR enhances resistance to cancer therapeutics is discussed, in addition to highlighting ways to target nuclear EGFR as an anti-cancer strategy in the future.

Natural selection and functional diversification of the epidermal growth factor receptor EGFR family in vertebrates

BACKGROUND

Genes that have been subject to adaptive evolution can produce varying degrees of pathology or differing symptomatology. ErbB family receptor activation will initiate a number of downstream signaling pathways, such as mitogen-activated protein kinase (MAPK), activator of transcription (STAT), the modulation of calcium channels, and so on, all of which lead to aggressive tumor behavior. However, the evolutionary mechanisms operating in the retention of ErbB family genes and the changes in selection pressures are not clear.

RESULTS

Sixty-two full-length cDNA sequences from 27 vertebrate species were extracted from the UniProt protein database, NCBI's GenBank and the Ensembl database. The result of phylogenetic analysis showed that the four ErbB family members in vertebrates might be formed by gene duplication. In order to determine the mode of evolution in vertebrates, selection analysis and functional divergence analysis were combined to explain the relationship of the site-specific evolution and functional divergence in the vertebrate ErbB family. Our results indicate that the acceleration of asymmetric evolutionary rates and purifying selection together were the main force for the production of ErbBs, and positive selections were detected in the ErbB family.

CONCLUSION

An evolutional phylogeny of 27 vertebrates was presented in our study; the tree showed that the genes have evolved through duplications followed by purifying selection, except for seven sites, which evolved by positive selection. There was one common site with positive selection and functional divergence. In the process of functional differentiation evolving through gene duplication, relaxed selection may play an important part.

Protein kinase Cδ is required for ErbB2-driven mammary gland tumorigenesis and negatively correlates with prognosis in human breast cancer

Protein kinase C δ (PKCδ) regulates apoptosis in the mammary gland, however, the functional contribution of PKCδ to the development or progression of breast cancer has yet to be determined. Meta-analysis of ErbB2-positive breast cancers shows increased PKCδ expression, and a negative correlation between PKCδ expression and prognosis. Here, we present in-vivo evidence that PKCδ is essential for the development of mammary gland tumors in a ErbB2-overexpressing transgenic mouse model, and in-vitro evidence that PKCδ is required for proliferative signaling downstream of the ErbB2 receptor. Mouse mammary tumor virus (MMTV)-ErbB2 mice lacking PKCδ (δKO) have increased tumor latency compared with MMTV-ErbB2 wild-type (δWT) mice, and the tumors show a dramatic decrease in Ki-67 staining. To explore the relationship between PKCδ and ErbB2-driven proliferation more directly, we used MCF-10A cells engineered to express a synthetic ligand-inducible form of the ErbB2 receptor. Depletion of PKCδ with short hairpin RNA inhibited ligand-induced growth in both two-dimensional (2D) (plastic) and three-dimensional (3D) (Matrigel) culture, and correlated with decreased phosphorylation of the ErbB2 receptor and reduced activation of Src and MAPK/ERK pathways. Similarly, in human breast cancer cell lines in which ErbB2 is overexpressed, depletion of PKCδ suppresses proliferation, Src and ERK activation. PKCδ appears to drive proliferation through the formation of an active ErbB2/PKCδ/Src signaling complex, as depletion of PKCδ disrupts association of Src with the ErbB2 receptor. Taken together, our studies present the first evidence that PKCδ is a critical regulator of ErbB2-mediated tumorigenesis, and suggest further investigation of PKCδ as a target in ErbB2-positive breast cancer.