Role of erbB2 in breast cancer chemosensitivity

The mediating effects of public genomic knowledge in precision medicine implementation: A structural equation model approach

Precision medicine emphasizes predictive, preventive and personalized treatment on the basis of information gleaned from personal genetic and environmental data. Its implementation at health systems level is regarded as multifactorial, involving variables associated with omics technologies, public genomic awareness and adoption tendencies for new medical technologies. However, interrelationships of the various factors and their synergy has not been sufficiently quantified. Based on a survey of 270 participants involved in the use of molecular tests (omics-based biomarkers, OBMs), this study examined how characteristics of omics biomarkers influence precision medicine implementation outcomes (ImO) through an intermediary factor, public genomic awareness (represented by User Response, UsR). A structural equation modelling (SEM) approach was applied to develop and test a 3 latent variable mediation model; each latent variable being measured by a set of indicators ranging between three and six. Mediation analysis results confirmed a partial mediation effect (an indirect effect represented as the product of paths 'a' and 'b' (a*b)) of 0.36 at 90% confidence level, CI = [0.03, 9.94]. Results from the individual mediation paths 'a' and 'b' however, showed that these effects were negative(a = -0.38, b = -0.94). Path 'a' represents the effect of characteristics of OBMs on the mediator, UsR; 'b' represents the effect of the mediator, UsR on implementation outcomes, ImO, holding OBMs constant. The results have both theoretical and practice implications for biomedical genomics research and clinical genomics, respectively. For instance, the results imply better ways have to be devised to more effectively engage the public in addressing extended family support for extended family cascade screening, especially for monogenic hereditary conditions like BRCA-related breast cancer and colorectal cancer in Lynch syndrome families. At basic biomedical research level, results suggest an integrated biomarker development pipeline, with early consideration of factors that may influence biomarker uptake. The results are also relevant at health systems level in indicating which factors should be addressed for successful.

An insertion mutation of ERBB2 enhances breast cancer cell growth and confers resistance to lapatinib through AKT signaling pathway

In clinical practice, some breast cancer (BC) patients carry a rare ERBB2 in-frame insertion (p. Pro780_Tyr781insGlySerPro) and are resistant to anti-ERBB2 therapy. To explore the potential procarcinogenic role of this ERBB2 mutation, we conducted the present study using BC cells overexpressing wild-type (WT) ERBB2 or P780-Y781 ERBB2 [mutated (MT)]. MDA-MB-231 and MCF-7 cells were transfected with the following plasmids using a lentivirus system: negative control (ERBB2-NC), WT ERBB2 overexpression (ERBB2-WT), and P780-Y781 ERBB2 overexpression (ERBB2-MT). P780-Y781 ERBB2 conferred significant resistance to lapatinib, as assessed by cell viability and colony counts. Analysis of the cell cycle showed that the P780-Y781 ERBB2 group showed an elevated proportion of cells in S, G2, and M phases compared with WT ERBB2 when exposed to lapatinib. Following lapatinib treatment, phosphorylated AKT (p-AKT) was strongly upregulated in the P780-Y781 ERBB2 group. Among ERBB2+ patients, the P780-Y781 ERBB2 group showed increased levels of p-AKT. Furthermore, the AKT inhibitor perifosine effectively suppressed lapatinib resistance, as indicated by the lapatinib inhibition curve and results of the colony formation assay, and decreased AKT phosphorylation. Altogether, we discovered a procarcinogenic mutation of ERBB2 that enhances BC cell growth through AKT signaling and causes resistance to lapatinib. Patients with this in-frame insertion mutation of ERBB2 should be recommended other therapeutic strategies apart from ERBB2 tyrosine kinase inhibitors, in particular lapatinib.

Phage display screening of therapeutic peptide for cancer targeting and therapy

Recently, phage display technology has been announced as the recipient of Nobel Prize in Chemistry 2018. Phage display technique allows high affinity target-binding peptides to be selected from a complex mixture pool of billions of displayed peptides on phage in a combinatorial library and could be further enriched through the biopanning process; proving to be a powerful technique in the screening of peptide with high affinity and selectivity. In this review, we will first discuss the modifications in phage display techniques used to isolate various cancer-specific ligands by in situ, in vitro, in vivo, and ex vivo screening methods. We will then discuss prominent examples of solid tumor targeting-peptides; namely peptide targeting tumor vasculature, tumor microenvironment (TME) and over-expressed receptors on cancer cells identified through phage display screening. We will also discuss the current challenges and future outlook for targeting peptide-based therapeutics in the clinics.

Phytoestrogens and mycoestrogens interacting with breast cancer proteins

Breast cancer is a highly heterogeneous disease influenced by the hormonal microenvironment and the most common malignancy in women worldwide. Some phytoestrogens and mycoestrogens have been epidemiologically linked as risk factors or protectors, however their mechanisms of action are complex and not fully understood. The aim of this study was to predict the potential of 36 natural xenoestrogens to interact with 189 breast cancer proteins using AutoDock Vina. In order to validate our protocol, an in silico docking pose and binding site determination was compared with the crystallographic structure and the power of prediction to distinguish between ligand and decoys was evaluated through a receiver operating characteristic curve (ROC) of the resultant docking affinities and in vitro data. The best affinity score was obtained for glyceollin III interacting with the sex hormone binding globulin (-11.9 Kcal/mol), a plasma steroid transport protein that regulates sex steroids bioavailability. Other natural xenoestrogens such as beta-carotene, chrysophanol 8-O-beta-d-glucopyranoside and glyceollin I, also presented good affinity for proteins related to this disease and the validation was successful. This study may help to prioritize compounds for toxicity tests or drug development from natural scaffolds, and to elucidate their mechanisms of action.

Comparative Gene Expression Profiling of Primary and Metastatic Renal Cell Carcinoma Stem Cell-Like Cancer Cells

Background

Recent advancement in cancer research has shown that tumors are highly heterogeneous, and multiple phenotypically different cell populations are found in a single tumor. Cancer development and tumor growth are driven by specific types of cells—stem cell-like cancer cells (SCLCCs)—which are also responsible for metastatic spread and drug resistance. This research was designed to verify the presence of SCLCCs in renal cell cancer cell lines. Subsequently, we aimed to characterize phenotype and cell biology of CD105+ cells, defined previously as renal cell carcinoma tumor-initiating cells. The main goal of the project was to describe the gene-expression profile of stem cell-like cancer cells of primary tumor and metastatic origin.

Materials and Methods

Real-time PCR analysis of stemness genes (Oct-4, Nanog and Ncam) and soft agar colony formation assay were conducted to check the stemness properties of renal cell carcinoma (RCC) cell lines. FACS analysis of CD105+ and CD133+ cells was performed on RCC cells. Isolated CD105+ cells were verified for expression of mesenchymal markers—CD24, CD146, CD90, CD73, CD44, CD11b, CD19, CD34, CD45, HLA-DR and alkaline phosphatase. Hanging drop assay was used to investigate CD105+ cell-cell cohesion. Analysis of free-floating 3D spheres formed by isolated CD105+ was verified, as spheres have been hypothesized to contain undifferentiated multipotent progenitor cells. Finally, CD105+ cells were sorted from primary (Caki-2) and metastatic (ACHN) renal cell cancer cell lines. Gene-expression profiling of sorted CD105+ cells was performed with Agilent’s human GE 4x44K v2 microarrays. Differentially expressed genes were further categorized into canonical pathways. Network analysis and downstream analysis were performed with Ingenuity Pathway Analysis.

Results

Metastatic RCC cell lines (ACHN and Caki-1) demonstrated higher colony-forming ability in comparison to primary RCC cell lines. Metastatic RCC cell lines harbor numerous CD105+ cell subpopulations and have higher expression of stemness genes (Oct-4 and Nanog). CD105+ cells adopt 3D grape-like floating structures under handing drop conditions. Sorted CD105+ cells are positive for human mesenchymal stem cell (MSC) markers CD90, CD73, CD44, CD146, and alkaline phosphatase activity, but not for CD24 and hematopoietic lineage markers CD34, CD11b, CD19, CD45, and HLA-DR. 1411 genes are commonly differentially expressed in CD105+ cells (both from primary [Caki-2] and metastatic RCC [ACHN] cells) in comparison to a healthy kidney epithelial cell line (ASE-5063). TGF-β, Wnt/β-catenine, epithelial-mesenchymal transition (EMT), Rap1 signaling, PI3K-Akt signaling, and Hippo signaling pathway are deregulated in CD105+ cells. TGFB1, ERBB2, and TNF are the most significant transcriptional regulators activated in these cells.

Conclusions

All together, RCC-CD105+ cells present stemlike properties. These stem cell-like cancer cells may represent a novel target for therapy. A unique gene-expression profile of CD105+ cells could be used as initial data for subsequent functional studies and drug design.

Suppression of human epidermal growth factor receptor 2 via interference increases the chemosensitivity of ovarian carcinoma

The function of human epidermal growth factor receptor 2 (HER2) in the chemosensitivity of ovarian carcinoma has not been fully investigated, therefore, the present study aimed to analyze the potential role of HER2 in ovarian carcinoma chemosensitivity in further detail. SKOV3 cells were transfected with lentiviral-mediated HER2-small hairpin RNA (shRNA) molecules to establish the stable expression of HER2-shRNA in the SKOV3 cell line (knockdown cells; KD) and negative control cell line (NC). The untransfected SKOV3 cell line served as the blank control (CON) group. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis were used to detect the expression of HER2 in the three different cell types, which were subsequently examined for growth inhibition using a cell counting kit-8 assay. The CON and KD cell strains were utilized to establish xenograft models in nude mice, primarily to detect the expression of the HER2 protein, and additionally to observe tumor size changes under the treatment of cisplatin (DDP) chemotherapy. RT-qPCR and western blot analysis demonstrated a significant decrease in the levels of HER2 mRNA and protein in the KD cells. The suppression of HER2 expression resulted in an increase of chemotherapy sensitivity in the SKOV3 cells. HER2 protein expression decreased significantly following transduction with specific HER2-shRNA. Additionally, growth slowed significantly under treatment with DDP in ovarian cancer transplantation tumors. In conclusion, lentivirus-mediated HER2-shRNA effectively inhibits the expression of the HER2 gene, and increases the chemosensitivity to DDP in ovarian carcinoma.

Blockade of a key region in the extracellular domain inhibits HER2 dimerization and signaling

BACKGROUND

Several treatment strategies target the human epidermal growth factor receptor 2 (HER2) in breast carcinomas, including monoclonal antibodies directed against HER2's extracellular domain (ECD) and small molecule inhibitors of its tyrosine kinase activity. Yet, novel therapies are needed that prevent HER2 dimerization with other HER family members, because current treatments are only partially effective.

METHODS

To test the hypothesis that HER2 activation requires a protein sequence in the HER2-ECD that mediates HER2 homo- and heterodimerization, we introduced a series of deletion mutations in the third subdomain of HER2-ECD. These deletion mutants were retrovirally expressed in breast cancer (BC) cells that naturally overexpress HER2 and in noncancerous, HER2-negative breast epithelial cells. One-factor analysis of variance or Student's t test were used to analyze differences. All statistical tests were two-sided.

RESULTS

The smallest deletion in the ECD domain of HER2, which removed only 16 amino acids (HER2-ECDΔ451-466), completely disrupted the oncogenic potential of HER2. In contrast to wild-type HER2, the mutant-inhibited anchorage-independent growth (mean number of colonies: mutant, 70, 95% confidence interval [CI] = 55 to 85; wild-type, 400, 95% CI = 320 to 480, P < .001) increased sensitivity to paclitaxel treatment in both transformed and nontransformed cells. Overexpression of HER2Δ451-466 efficiently inhibited activation of HER1, HER2, and HER3 in all cell lines tested.

CONCLUSIONS

These findings reveal that an essential "activating" sequence exists in the extracellular domain of HER2. Disruption of this sequence disables the HER2 dimerization loop, blocks subsequent activation of HER2-driven oncogenic signaling, and generates a dominant-negative form of HER2. Reagents specifically against this molecular activation switch may represent a novel targeted approach for the management of HER2-overexpressing carcinomas.

Trastuzumab increases the sensitivity of HER2-amplified human gastric cancer cells to oxaliplatin and cisplatin by affecting the expression of telomere-associated proteins

HER2 amplification occurs in ~20% of gastric cancer (GC) cases; however, in gastric and gastroesophageal junction cancer with HER2 gene amplification, trastuzumab in combination with cisplatin (DDP)-based chemotherapy has been reported to improve the oncological outcome. The aim of the present study was to evaluate the combined antitumor efficacy of trastuzumab and various platinum agents in GC cells and to elucidate mechanisms that may be involved in the interaction between trastuzumab and the platinum agents. The in vitro chemosensitivity of the GC cells to platinum agents was evaluated using the CellTiter 96^® AQueous One Solution Cell Proliferation Assay kit. Treatment with 1.0μg/ml trastuzumab for 48 h significantly increased the sensitivity of NCI-N87 cells with HER2 amplification to oxaliplatin (Oxa) and DDP. This chemosensitivity was most prominent in the NCI-N87 cells, in which the half maximal inhibitory concentration of Oxa and DDP was decreased to ~3.29 and 6.91 times, respectively. The apoptotic effect of the platinum agents was evaluated by double-staining the GC cells with Annexin V-fluorescein isothiocyanate and propodium iodide. Consistent with the chemosensitivity analysis, apoptotic analysis indicated that trastuzumab significantly increased Oxa- and DDP-induced apoptosis in the NCI-N87 cells. Furthermore, the mRNA expression levels of various telomere-associated genes was determined by performing quantitative reverse transcription-polymerase chain reactions in a number of GC cell lines, and revealed that trastuzumab (alone and in combination with DDP) may downregulate the mRNA expression levels of the TPP1, TRF1, TRF2, TRF2IP and POT1 genes. However, western blot analysis demonstrated that trastuzumab (alone and in combination with DDP) may significantly downregulate the protein expression levels of telomeric repeat binding factor 2, protection of telomere 1 and TPP1 (formerly known as TINT1, PTOP and PIP). The results of the present study indicate a potential role of low-dose trastuzumab administration for increasing Oxa and DDP sensitivity in HER2-amplified GC cells, possibly via the downregulation of telomere-associated gene expression.

Histone deacetylase inhibitors in oral squamous cell carcinoma treatment

Introduction: The involvement of the histone deacetylases (HDACs) family in tumor development and progression is well demonstrated. HDAC inhibitors (HDACis) constitute a novel, heterogeneous family of highly selective anticancer agents that inhibit HDACs and present significant antitumor activity in several human malignancies, including oral squamous cell carcinoma (OSCC). Areas covered: This review summarizes the current research on the anticancer activity of HDACis against OSCC. The review also presents the molecular mechanisms of HDACis action and the existing studies evaluating their utilization in combined therapies of OSCC. Expert opinion: The currently available data support evidence that HDACis may provide new therapeutic options against OSCC, decreasing treatment side effects and allowing a more conservative therapeutic approach. Future research should be focused on in vivo and clinical evaluation of their utilization as combined therapies or monotherapies. Before HDACis can be brought into clinical practice as treatment options for OSCC, further evaluation is needed to determine their optimal dosage, the appropriate duration of treatment and whether they should be used in combination or as stand-alone therapeutics.

Photochemical activation of the recombinant HER2-targeted fusion toxin MH3-B1/rGel; Impact of HER2 expression on treatment outcome

HER2 is overexpressed in 20-30% of breast tumors and is associated with aggressiveness and increased risk of recurrence and death. The HER2 protein is internalized as a part of its activity, and may therefore be utilized as a target for the specific intracellular delivery of drugs. Photochemical internalization (PCI) is a novel technology now undergoing clinical evaluation for its ability to improve the release into the cytosol of drugs entrapped in the endo/lysosomal compartment. PCI employs an amphiphilic photosensitizer which localizes in the membranes of endo/lysosomes. Subsequent light exposure (visible light) causes destabilization of the endo/lysosomal membranes. PCI has been proven highly effective for improving the cytosolic delivery of targeted toxins based on type I ribosome inactivating protein toxins such as gelonin. We examined the impact of the level of target antigen expression on PCI efficacy. Four human breast cancer cell lines (MDA-MB-231, BT-20, Zr-75-1 and SK-BR-3) covering a wide range of HER2 expression were included in the present study. PCI of the HER2-targeted fusion toxin MH3-B1/rGel was found to be highly effective in all four cell lines. The increase in PCI-mediated efficacy was not directly correlated with the cellular levels of HER2 as assessed by western blots, the overall uptake of MH3-B1/rGel as measured by flow cytometry, the amount of MH3-B1/rGel localized to endo/lysosomes assessed by confocal microscopy or the cell sensitivity to the photochemical treatment itself (photosensitizer and light without MH3-B1/rGel). However, correcting the PCI efficacy for the baseline cellular sensitivity to rGel revealed a linear correlation (R(2)=0.80) with HER2 expression. The present report therefore concludes the cellular sensitivity to the toxin as an important parameter for PCI efficacy and also indicates PCI of a HER2-targeted fusion toxin as an attractive treatment alternative for breast cancer patients with both HER2-low and -high expression.

Α-eleostearic acid inhibits growth and induces apoptosis in breast cancer cells via HER2/HER3 signaling

α-eleostearic acid (α-ESA) has been shown to possess antitumor activity in cancer cells. However, the underlying mechanism(s) remain largely unknown. The present study was designed to investigate the antitumor effect of α-ESA in breast cancer cells showing different expression levels of the human epidermal growth factor receptor 2 (HER2). α-ESA inhibited cell growth and induced apoptosis in the SKBR3 and T47D breast cancer cell lines. The mechanism by which cell growth was inhibited involved G0/G1 and G2/M cell cycle phase arrest. The MTT assay showed that SKBR3 cells are more sensitive to α-ESA compared to T47D cells. Western blot analysis revealed that α-ESA treatment not only reduced HER2/HER3 protein expression, but also increased the level of phosphorylated phosphatase and tensin homolog protein (PTEN), which led to decreased levels of phosphorylated Akt. Inactive Akt further reduced phosphorylation of glycogen synthase kinase-3β (GSK-3β) and B-cell lymphoma 2 (Bcl-2)‑associated death promoter (BAD) proteins. Furthermore, the level of the anti-apoptotic protein Bcl-2 was found to be reduced following α-ESA treatment. Notably, nuclear factor κB (NF-κB) was activated by α-ESA treatment. Data of the present study showed that the antitumor activity of α-ESA is at least partly mediated by reduction of the HER2/HER3 heterodimer protein level, activation of the Akt/BAD/Bcl-2 apoptotic pathway and inhibition of the Akt/GSK-3β survival pathway in the two breast cancer cell lines investigated in this study. Therefore, α-ESA may be considered a beneficial dietary factor for the prevention and treatment of invasive breast cancer in cells overexpressing HER2.

Inhibition of the HER2 pathway by n-3 polyunsaturated fatty acids prevents breast cancer in fat-1 transgenic mice

Overexpression of the tyrosine kinase receptor, ErbB2/HER2/Neu, occurs in 25-30% of invasive breast cancer (BC) with poor patient prognosis. Due to confounding factors, inconsistencies still remain regarding the protective effects of n-3 polyunsaturated fatty acids (PUFAs) on BC. We therefore evaluated whether fat-1 transgenic mice, endogenously synthesizing n-3 PUFAs from n-6 PUFAs, were protected against BC development, and we then aimed to study in vivo a mechanism potentially involved in such protection. E0771 BC cells were implanted into fat-1 and wild-type (WT) mice. After tumorigenesis examination, we analyzed the expression of proteins involved in the HER2 signaling pathway and lipidomic analyses were performed in tumor tissues and plasma. Our results showed that tumors totally disappeared by day 15 in fat-1 mice but continued to grow in WT mice. This prevention can be related in part to significant repression of the HER2/β-catenin signaling pathway and formation of significant levels of n-3 PUFA-derived bioactive mediators (particularly 15-hydroxyeicosapentaenoic acid, 17-hydroxydocosahexaenoic acid, and prostaglandin E3) in the tumors of fat-1 mice compared with WT mice. All together these data demonstrate an anti-BC effect of n-3 PUFAs through, at least in part, HER2 signaling pathway downregulation, and highlight the importance of gene-diet interactions in BC.

n-3 polyunsaturated fatty acids and HER2-positive breast cancer: interest of the fat-1 transgenic mouse model over conventional dietary supplementation

Overexpression of the tyrosine kinase receptor ErbB2/HER2/Neu, occurs in 25%-30% of invasive breast cancer (BC) with poor patient prognosis. Even if numerous studies have shown prevention of breast cancer by n-3 fatty acid intake, the experimental conditions under which n-3 fatty acids exert their protective effect have been variable from study to study, preventing unifying conclusions. Due to confounding factors, inconsistencies still remain regarding protective effects of n-3 polyunsaturated fatty acids (PUFA) on BC. When animals are fed with dietary supplementation in n-3 fatty acids (the traditional approach to modify tissue content and decrease the n-6/n-3 ratio) complex dietary interactions can occur among dietary lipids (antioxidants, vitamins…) that can modulate the activity of n-3 fatty acids. So, what are the specific roles of these n-3 PUFA in reducing breast cancer risk and particularly preventing HER2-positive breast cancer? In this review, we discuss crucial points that may account for discrepancies of results and provide a highly effective genetic approach that can eliminate confounding factors of diet for evaluating the molecular mechanisms of n-3 PUFA in HER2 signaling pathway regulation. The fat-1 transgenic mouse model is capable of converting n-6 to n-3 fatty acids leading to an increase in n-3 fatty acid content with a balanced n-6/n-3 fatty acid ratio in all tissues. The fat-1 mouse model allows well-controlled studies in HER2-positive breast cancer prevention to be performed, without the conflict of potential confounding factors of diet.

The mitotic kinase Aurora--a promotes distant metastases by inducing epithelial-to-mesenchymal transition in ERα(+) breast cancer cells

In this study, we demonstrate that constitutive activation of Raf-1 oncogenic signaling induces stabilization and accumulation of Aurora-A mitotic kinase that ultimately drives the transition from an epithelial to a highly invasive mesenchymal phenotype in estrogen receptor α-positive (ERα(+)) breast cancer cells. The transition from an epithelial- to a mesenchymal-like phenotype was characterized by reduced expression of ERα, HER-2/Neu overexpression and loss of CD24 surface receptor (CD24(-/low)). Importantly, expression of key epithelial-to-mesenchymal transition (EMT) markers and upregulation of the stemness gene SOX2 was linked to acquisition of stem cell-like properties such as the ability to form mammospheres in vitro and tumor self-renewal in vivo. Moreover, aberrant Aurora-A kinase activity induced phosphorylation and nuclear translocation of SMAD5, indicating a novel interplay between Aurora-A and SMAD5 signaling pathways in the development of EMT, stemness and ultimately tumor progression. Importantly, pharmacological and molecular inhibition of Aurora-A kinase activity restored a CD24(+) epithelial phenotype that was coupled to ERα expression, downregulation of HER-2/Neu, inhibition of EMT and impaired self-renewal ability, resulting in the suppression of distant metastases. Taken together, our findings show for the first time the causal role of Aurora-A kinase in the activation of EMT pathway responsible for the development of distant metastases in ERα(+) breast cancer cells. Moreover, this study has important translational implications because it highlights the mitotic kinase Aurora-A as a novel promising therapeutic target to selectively eliminate highly invasive cancer cells and improve the disease-free and overall survival of ERα(+) breast cancer patients resistant to conventional endocrine therapy.

Involvement of CXCR4 chemokine receptor in metastastic HER2-positive esophageal cancer

A functional linkage of the structurally unrelated receptors HER2 and CXCR4 has been suggested for breast cancer but has not been evaluated for esophageal carcinoma. The inhibition of HER2 leads to a reduction of primary tumor growth and metastases in an orthotopic model of esophageal carcinoma. The chemokine receptor CXCR4 has been implicated in metastatic dissemination of various tumors and correlates with poor survival in esophageal carcinoma. The aim of this study was to investigate a correlation between the expression levels of HER2 and CXCR4 and to evaluate the involvement of CXCR4-expression in HER2-positive esophageal carcinoma. The effects of HER2-inhibition with trastuzumab and of CXCR4-inhibition with AMD3100 on primary tumor growth, metastatic homing, and receptor expression were evaluated in vitro and in an orthotopic model of metastatic esophageal carcinoma using MRI for imaging. The clinical relevance of HER2- and CXCR4-expression was examined in esophageal carcinoma patients. A significant correlation of HER2- and CXCR4-expression in primary tumor and metastases exists in the orthotopic model. Trastuzumab and AMD3100 treatment led to a significant reduction of primary tumor growth, metastases and micrometastases. HER2-expression was significantly elevated under AMD3100 treatment in the primary tumor and particularly in the metastases. The positive correlation between HER2- and CXCR4-expression was validated in esophageal cancer patients. The correlation of CXCR4- and HER2-expression and the elevation of HER2-expression and reduction of metastases through CXCR4-inhibition suggest a possible functional linkage and a role in tumor dissemination in HER2-positive esophageal carcinoma.

NRF2 inhibition represses ErbB2 signaling in ovarian carcinoma cells: implications for tumor growth retardation and docetaxel sensitivity

NF-E2-related factor 2 (NRF2) is a transcription factor that regulates the expression of various antioxidant and detoxifying enzymes. Although the benefit of NRF2 in cancer prevention is well established, its role in cancer pathobiology was recently discovered. In this study, the role of NRF2 in tumor growth and docetaxel sensitivity was investigated in ErbB2-overexpressing ovarian carcinoma SKOV3 cells. Interfering RNA-mediated stable inhibition of NRF2 in SKOV3 cells repressed NRF2 signaling, resulting in cell growth arrest at G(0)/G(1) phase and tumor growth retardation in mouse xenografts. Microarray analysis revealed that ErbB2 expression is substantially reduced in NRF2-inhibited SKOV3 and this was further confirmed by RT-PCR and immunoblot analysis. Repression of ErbB2 led to a decrease in phospho-AKT and enhanced p27 protein, reinforcing the effect of NRF2 knockdown on SKOV3 growth. Furthermore, NRF2 inhibition-mediated ErbB2 repression increases the sensitivity of these cells to docetaxel cytotoxicity and apoptosis. The linkage between NRF2 and ErbB2 was confirmed in the ErbB2-positive breast cancer cell line BT-474: NRF2 knockdown suppressed ErbB2 expression and enhanced docetaxel sensitivity. Our results provide insight into the coordinated regulation of signaling molecules responding to environmental stress and suggest that NRF2 modulation might be a therapeutic strategy to limit tumor growth and enhance sensitivity to taxane-based chemotherapy.

Increasing CD44+/CD24(-) tumor stem cells, and upregulation of COX-2 and HDAC6, as major functions of HER2 in breast tumorigenesis

Background

Cancer cells are believed to arise primarily from stem cells. CD44⁺/CD24^- have been identified as markers for human breast cancer stem cells. Although, HER2 is a well known breast cancer oncogene, the mechanisms of action of this gene are not completely understood. Previously, we have derived immortal (M13SV1), weakly tumorigenic (M13SV1R2) and highly tumorigenic (M13SV1R2N1) cell lines from a breast epithelial cell type with stem cell phenotypes after successive SV40 large T-antigen transfection, X-ray irradiation and ectopic expression of HER2/C-erbB2/neu. Recently, we found that M13SV1R2 cells became non-tumorigenic after growing in a growth factor/hormone-deprived medium (R2d cells).

Results

In this study, we developed M13SV1R2N1 under the same growth factor/hormone-deprived condition (R2N1d cells). This provides an opportunity to analyze HER2 effect on gene expression associated with tumorigenesis by comparative study of R2d and R2N1d cells with homogeneous genetic background except HER2 expression. The results reveal distinct characters of R2N1d cells that can be ascribed to HER2: 1) development of fast-growing tumors; 2) high frequency of CD44⁺/CD24^- cells (~50% for R2N1d vs. ~10% for R2d); 3) enhanced expression of COX-2, HDAC6 mediated, respectively, by MAPK and PI3K/Akt pathways, and many genes associated with inflammation, metastasis, and angiogenesis. Furthermore, HER2 expression can be down regulated in non-adhering R2N1d cells. These cells showed longer latent period and lower rate of tumor development compared with adhering cells.

Conclusions

HER2 may induce breast cancer by increasing the frequency of tumor stem cells and upregulating the expression of COX-2 and HDAC6 that play pivotal roles in tumor progression.

Building Cell Selectivity into CPP-Mediated Strategies

There is a pressing need for more effective and selective therapies for cancer and other diseases. Consequently, much effort is being devoted to the development of alternative experimental approaches based on selective systems, which are designed to be specifically directed against target cells. In addition, a large number of highly potent therapeutic molecules are being discovered. However, they do not reach clinical trials because of their low delivery, poor specificity or their incapacity to bypass the plasma membrane. Cell-penetrating peptides (CPPs) are an open door for cell-impermeable compounds to reach intracellular targets. Putting all these together, research is sailing in the direction of the design of systems with the capacity to transport new drugs into a target cell. Some CPPs show cell type specificity while others require modifications or form part of more sophisticated drug delivery systems. In this review article we summarize several strategies for directed drug delivery involving CPPs that have been reported in the literature.

Membrane-bound mucins: the mechanistic basis for alterations in the growth and survival of cancer cells

Mucins (MUC) are high molecular weight O-linked glycoproteins whose primary functions are to hydrate, protect, and lubricate the epithelial luminal surfaces of the ducts within the human body. The MUC family is comprised of large secreted gel forming and transmembrane (TM) mucins. MUC1, MUC4, and MUC16 are the well-characterized TM mucins and have been shown to be aberrantly overexpressed in various malignancies including cystic fibrosis, asthma, and cancer. Recent studies have uncovered the unique roles of these mucins in the pathogenesis of cancer. These mucins possess specific domains that can make complex associations with various signaling pathways, impacting cell survival through alterations of cell growth, proliferation, death, and autophagy. The cytoplasmic domain of MUC1 serves as a scaffold for interaction with various signaling proteins. On the other hand, MUC4 mediates its effect by stabilizing and enhancing the activity of growth factor receptor ErbB2. MUC16, previously known as CA125, is a well-known serum marker for the diagnosis of ovarian cancer and has a key role in stimulation and dissemination of ovarian cancer cells by interacting with mesothelin and galectin. Therefore, herein we discuss the function and divergent mechanisms of MUC1, MUC4, and MUC16 in carcinogenesis in the context of alteration in cell growth and survival.

The effect of hydrophilic substitutions and anionic lipids upon the transverse positioning of the transmembrane helix of the ErbB2 (neu) protein incorporated into model membrane vesicles

The sequence of the transmembrane (TM) helix of ErbB2, a member of the epidermal growth factor receptor (ErbB) family, can influence its activity. In this report, the sequence and lipid dependence of the transverse position of a model-membrane-inserted peptides containing the ErbB2 TM helix and some of the juxtamembrane (JM) residues were studied. For the ErbB2 TM helix inserted into phosphatidylcholine vesicles, the activating V664E mutation was found to induce a transverse shift involving the movement of the E residue toward the membrane surface. This shortened the effective length of the TM-spanning portion of the sequence. The transverse shift was observed with the E664 residue in both the uncharged and charged states, but the extent of the shift was larger when the E residue was charged. When a series of hydrophilic residues was substituted for V664, the resulting transverse shifts at pH 7.0 decreased in the order D,H>E>Q>K>G>V. Except for His, this order is strongly correlated to that reported for the degree to which these substitutions induce cellular transformation when introduced into full-length ErbB2. To examine the effect of lipid on transverse shift, we studied the uncharged V664Q mutation. The presence of 20% of the anionic lipid DOPS (dioleoylphosphatidylserine) in the model membrane vesicles, which introduces a physiologically relevant level of anionic lipid, did not affect the degree of transverse shift. However, in the case of a peptide containing a V674Q substitution, in which the Q is closer to the C-terminus of the ErbB2 TM helix than the N-terminus, transverse shift was suppressed in vesicles containing 20% DOPS. This suggests that the interaction of the cationic JM residues flanking the C-terminus of the ErbB2 TM helix interact with anionic lipids to anchor the C-terminal end of the TM helix. This anchoring site may act as a pivot that amplifies transverse movements of the ErbB2 TM segment to induce a large swinging-type motion in the extracellular domain of the protein, affecting ErbB2 activity. Interactions interrupting C-terminal JM residue association with anionic lipid might partly impact ErbB2 activity by disrupting this pivoting.

Phosphorylated/Activated HER2 as a Marker of Clinical Resistance to Single Agent Taxane Chemotherapy for Metastatic Breast Cancer

Purpose. To determine the association of phosphorylated/activated HER2 (P-HER2) and response to taxane chemotherapy in patients with metastatic breast cancer (MBC). Materials and Methods. Archived tumor specimens of patients with MBC treated on clinical trials with taxane monotherapy were analyzed by immunohistochemistry (IHC) for the presence of phosphorylated HER2 using the PN2A monoclonal antibody. Chi-squared analysis was performed to evaluate the association of P-HER2 status and efficacy of single agent taxane therapy. Results. One hundred twenty-six cases were identified as evaluable for both IHC and clinical outcome. Twelve cases (10 percent) were positive for P-HER2, of which 5 had evidence of clinical progression and 7 had evidence of clinical benefit with taxane therapy. Of the 114 cases that were negative for P-HER2, 20 demonstrated progression and 94 had clinical benefit. Chi-squared analysis revealed a significant correlation between the presence of P-HER2 and resistance to taxane therapy, chi2 = 3.9724 and p = 0.046. Conclusions. Phosphorylated/activated HER2 is associated with clinical resistance to single agent taxane therapy for MBC. The likelihood of direct progression of disease on taxane was greater in cases of PN2A-positive tumors (42 percent) as opposed to PN2A-negative ones (18 percent, p = 0.046). Functional assessment of HER2 status may provide unique predictive information not seen with conventional assessments.

ErbB2-mediated Src and signal transducer and activator of transcription 3 activation leads to transcriptional up-regulation of p21Cip1 and chemoresistance in breast cancer cells

Overexpression of the ErbB2 receptor tyrosine kinase is prevalent in approximately 30% of human breast cancers and confers Taxol resistance. Our previous work has shown that ErbB2 inhibits Taxol-induced apoptosis in breast cancer cells by transcriptionally up-regulating p21(Cip1). However, the mechanism of ErbB2-mediated p21(Cip1) up-regulation is unclear. Here, we show that ErbB2 up-regulates p21(Cip1) transcription through increased Src activity in ErbB2-overexpressing cells. Src activation further activated signal transducer and activator of transcription 3 (STAT3) that recognizes a SIE binding site on the p21(Cip1) promoter required for ErbB2-mediated p21(Cip1) transcriptional up-regulation. Both Src and STAT3 inhibitors restored Taxol sensitivity in resistant ErbB2-overexpressing breast cancer cells. Our data suggest that ErbB2 overexpression can activate STAT3 through Src leading to transcriptional up-regulation of p21(Cip1) that confers Taxol resistance of breast cancer cells. Our study suggests a potential clinical application of Src and STAT3 inhibitors in Taxol sensitization of ErbB2-overexpressing breast cancers.

Down-regulation of myeloid cell leukemia-1 through inhibiting Erk/Pin 1 pathway by sorafenib facilitates chemosensitization in breast cancer

Myeloid cell leukemia-1 (Mcl-1), a Bcl-2-like antiapoptotic protein, plays a role in cell immortalization and chemoresistance in a number of human malignancies. A peptidyl-prolyl cis/trans isomerase, Pin1 is involved in many cellular events, such as cell cycle progression, cell proliferation, and differentiation through isomerizing prophosphorylated substrates. It has been reported that down-regulation of Pin1 induces apoptosis, and that Erk phosphorylates and up-regulates Mcl-1; however, the underlying mechanisms for the two phenomena are not clear yet. Here, we showed that Pin 1 stabilizes Mcl-1, which is required for Mcl-1 posphorylation by Erk. First, we found expression of Mcl-1 and Pin1 were positively correlated and associated with poor survival in human breast cancer. We then showed that Erk could phosphorylate Mcl-1 at two consensus residues, Thr 92 and 163, which is required for the association of Mcl-1 and Pin1, resulting in stabilization of Mcl-1. Moreover, Pin1 is also required for the up-regulation of Mcl-1 by Erk activation. Based on this newly identified mechanism of Mcl-1 stabilization, two strategies were used to overcome Mcl-1-mediated chemoresistance: inhibiting Erk by Sorafenib, an approved clinical anticancer drug, or knocking down Pin1 by using a SiRNA technique. In conclusion, the current report not only unravels a novel mechanism to link Erk/Pin1 pathway and Mcl-1-mediated chemoresistance but also provides a plausible combination therapy, Taxol (Paclitaxel) plus Sorafenib, which was shown to be effective in killing breast cancer cells.

Her-2/neu-induced "cytokine signature" in breast cancer

Identification of genes/proteins that are differentially expressed in HER2-overexpressing breast carcinomas (BC) is essential in elucidating the mechanistic basis of their increased metastastic potential. With the goal of identifying a unique HER2-induced "cytokine signature" in BC, Human Cytokine Array III (RayBiotech, Inc.) simultaneously detecting 42 cytokines and growth factors on one membrane was used to determine the profile of cytokines in conditioned media obtained from MCF-7/Her2-18 cells, a MCF-7-derived clone engineered to stably express the full-length human HER2 cDNA, and from the MCF-7/neo control sub-line. We identified two inflammatory and proangiogenic CXC chemokines with at least a 10-fold increased expression in MCF-7/Her2-18 transfectants when compared with matched control MCF-7/neo cells: CXCL8 (IL-8; interleukin-8) and CXCL1 and (GRO; growth-related oncogene). HER2 up-regulation of IL-8 and GRO was validated by ELISA and further confirmed by switching off the HER2 signaling. Treatment with the tyrosine kinase inhibitor gefitinib (Iressa) returned the expression levels of IL-8 and GRO back to the baseline observed in HER2-negative MCF-7 BC cells. Moreover, IL-8 and GRO circulating levels were significantly higher in sera from HER2-positive BC patients. These findings reveal for the first time that (a) Enhanced synthesis and secretion of members of the IL-8/GRO chemokine family, which have recently been linked to estrogen receptor (ER) inaction, increased cell invasion, and angiogenesis, may represent a new pathway involved in the metastatic progression and endocrine resistance of HER2-overexpressing breast carcinomas; and (b) Circulating levels of IL-8 and GRO cytokines may represent novel biomarkers monitoring BC responses to endocrine treatments and/or HER2-targeted therapies.

Bile acid exposure up-regulates tuberous sclerosis complex 1/mammalian target of rapamycin pathway in Barrett's-associated esophageal adenocarcinoma

Barrett's esophagus, a columnar metaplasia of the lower esophagus epithelium related to gastroesophageal reflux disease, is the strongest known risk factor for the development of esophageal adenocarcinoma (EAC). Understanding the signal transduction events involved in esophageal epithelium carcinogenesis may provide insights into the origins of EAC and may suggest new therapies. To elucidate the molecular pathways of bile acid-induced tumorigenesis, the newly identified inflammation-associated signaling pathway involving I kappaB kinases beta (IKK beta), tuberous sclerosis complex 1 (TSC1), and mammalian target of rapamycin (mTOR) downstream effector S6 kinase (S6K1) was confirmed to be activated in immortalized Barrett's CPC-A and CPC-C cells and esophageal cancer SEG-1 and BE3 cells. Phosphorylation of TSC1 and S6K1 was induced in response to bile acid stimulation. Treatment of these cells with the mTOR inhibitor rapamycin or the IKK beta inhibitor Bay 11-7082 suppressed bile acid-induced cell proliferation and anchorage-independent growth. We next used an orthotopic rat model to evaluate the role of bile acid in the progression of Barrett's esophagus to EAC. Of interest, we found high expression of phosphorylated IKK beta (pIKK beta) and phosphorylated S6K1 (pS6K1) in tumor tissues and the Barrett's epithelium compared with normal epithelium. Furthermore, immunostaining of clinical EAC tissue specimens revealed that pIKK beta expression was strongly correlated with pS6K1 level. Together, these results show that bile acid can deregulate TSC1/mTOR through IKK beta signaling, which may play a critical role in EAC progression. In addition, Bay 11-7082 and rapamycin may potentially be chemopreventive drugs against Barrett's esophagus-associated EAC.

Downregulation of HER2 by RIG1 involves the PI3K/Akt pathway in ovarian cancer cells

Interferon-gamma (IFN-gamma) is known to downregulate HER2 oncoprotein (p185(HER2) or briefly p185) in prostate cancer cells. We demonstrate that the IFN-gamma-induced retinoid-inducible gene 1 (RIG1) acts as a transrepressor of p185. Furthermore, we exhibit that RIG1 downregulates the activated (phosphorylated) form of p185 and phosphoinositide-3 kinase (PI3K)/serine/threonine-specific protein kinase (Akt) and the mammalian target of rapamycin (mTOR), downstream substrates of HER2. We also elucidate that heregulin (HRG) specifically restores the activation of p185 and Akt after their activities are reduced by RIG1. Additionally, expression of vascular endothelial growth factor (VEGF) increases through the HER2- and Akt/mTOR-signaling pathways, indicating that VEGF is downregulated by RIG1 within the cell. These findings suggest that RIG1 plays a role in IFN-gamma-mediated therapy by downregulating p185 and its downstream PI3K/Akt/mTOR/VEGF-signaling pathway. These results may provide a new therapeutic mechanism for the clinical use of IFN-gamma and RIG1.

Does HER2 immunoreactivity provide prognostic information in locally advanced urothelial carcinoma patients receiving adjuvant M-VEC chemotherapy?

INTRODUCTION

To evaluate the impact of HER2 immunoreactivity on clinical outcome in locally advanced urothelial carcinoma patients who received surgery alone, or methotrexate, vinblastine, epirubicin, and cisplatin (M-VEC) as adjuvant chemotherapy.

MATERIALS AND METHODS

We studied 114 formalin-fixed paraffin-embedded specimens obtained from locally advanced urothelial carcinoma patients receiving surgery alone or adjuvant M-VEC. The authors evaluated HER2 immunoreactivity using immunohistochemical staining and explored the influence of pathological parameters and HER2 immunoreactivity on progression-free survival (PFS) and disease-specific overall survival (OS) using univariate and multivariate Cox's analyses.

RESULTS

Urothelial carcinoma of the bladder had a significantly higher frequency of HER2 immunoreactivity than that of the upper urinary tract (60.7 vs. 20.7%, p < 0.0001). Overall, nodal status was a strong and independent prognostic indicator for clinical outcome. The HER2 immunoreactivity was significantly associated with PFS (p = 0.02) and disease-specific OS (p = 0.005) in advanced urothelial carcinoma patients. As for patients with adjuvant M-VEC, HER2 immunoreactivity was a significant prognostic factor for PFS (p = 0.03) and disease-specific OS (p = 0.02) using univariate analysis, but not multivariate analysis, and not for patients receiving watchful waiting.

CONCLUSIONS

HER2 immunoreactivity might have a limited prognostic value for advanced urothelial carcinoma patients with adjuvant M-VEC.

Trastuzumab-resistant HER2-driven breast cancer cells are sensitive to epigallocatechin-3 gallate

Overexpression of the epidermal growth factor receptor family member HER2 is found in approximately 30% of breast cancers and is a target for immunotherapy. Trastuzumab, a humanized monoclonal antibody against HER2, is cytostatic when added alone and highly successful in clinical settings when used in combination with other chemotherapeutic agents. Unfortunately, HER2 tumors in patients develop resistance to trastuzumab or metastasize to the brain, which is inaccessible to antibody therapy. Previously, we showed that the green tea polyphenol epigallocatechin-3 gallate (EGCG) inhibits growth and transformed phenotype of Her-2/neu-driven mouse mammary tumor cells. The different modes of action of EGCG and trastuzumab led us to hypothesize that EGCG will inhibit HER2-driven breast cancer cells resistant to trastuzumab. We studied trastuzumab-resistant BT474 human breast cancer cells, isolated by chronic trastuzumab exposure, and JIMT-1 breast cancer cells, derived from a pleural effusion in a patient who displayed clinical resistance to trastuzumab therapy. EGCG treatment caused a dose-dependent decrease in growth and cellular ATP production, and apoptosis at high concentrations. Akt activity was suppressed by EGCG leading to the induction of FOXO3a and target cyclin-dependent kinase inhibitor p27Kip1 levels. Thus, EGCG in combination with trastuzumab may provide a novel strategy for treatment of HER2-overexpressing breast cancers, given that EGCG can cross the blood-brain barrier.

Efficient growth inhibition of ErbB2-overexpressing tumor cells by anti-ErbB2 ScFv-Fc-IL-2 fusion protein in vitro and in vivo

AIM

To investigate the antitumor activities of an anti-ErbB2 scFv-Fc-interleukin 2 (IL-2) fusion protein (HFI) in vitro and in vivo.

METHODS

Fusion protein HFI was constructed. The efficacy of HFI in mediating tumor cell lysis was determined by colorimetric lactate dehydrogenase release assays. The antitumor activity of HFI was evaluated in tumor xenograft models.

RESULTS

The fusion protein was folded as a homodimer formed by covalently linking Fc portions and it retained ErbB2 specificity and IL-2 biological activity. HFI mediated antibody-dependent cell-mediated cytotoxicity (ADCC) at low effector-to-target ratios in vitro and improved the therapeutic efficacy of IL-2 in experiments in vivo.

CONCLUSION

The genetically-engineered anti-ErbB2 scFv-Fc-IL-2 fusion protein exhibited high efficiency both in mediating ADCC in vitro and significant antitumor activity in tumor xenograft models.

Multiple mechanisms of Erbb2 action after ultraviolet irradiation of the skin

Ultraviolet (UV) irradiation causes multiple pathologic changes in the skin including inflammation, immune suppression, photoaging, and cancer. Effects of UV irradiation include the activation of numerous signal transduction pathways, including the mitogen-activated protein kinases (MAPK), and the activation of transcription factors such as nuclear factor kappa B (NFkappaB). These responses alter gene expression in a manner that resembles the response to growth factors known as the "UV response". The UV response alters the kinetics of cell division and cell death allowing the skin to recover from the DNA damage caused by UV exposure. UV irradiation also rapidly activates epidermal growth factor receptor (EGFR) family members, including Erbb2 (human epithelial growth factor receptor 2 (HER2)/neu), through the generation of reactive oxygen species. Erbb2, a protooncogene that is activated in many types of cancer and associated with aggressive and chemotherapeutic-resistant disease, is expressed in both follicular and epidermal keratinocytes within the skin. However, the physiological functions of Erbb2 in the skin and its role in the UV response are largely unknown. In this review, evidence that Erbb2 is influential in modulating the response of the skin to UV will be presented. Erbb2 alters the expression of regulatory genes controlling inflammation, angiogenesis, cell division, apoptosis, cell adhesion, and migration following UV irradiation. In addition, Erbb2 dampens UV-induced S-phase arrest, augments inflammation in response to UV irradiation, and suppresses UV-induced apoptosis. In summary, the evidence presented herein links UV-induced Erbb2 activation to many of the effects of UV and implicates Erbb2 in UV-induced carcinogenesis.

BMS-275183-induced gene expression patterns in head and neck carcinoma

PURPOSE

BMS-275183 is an orally bioavailable taxane that has antitumor activity in preclinical cancer models. However, limited BMS-275183 studies have been performed in head and neck squamous cell carcinoma (HNSCC) cell lines. The purpose of this study is to identify the biological activity of BMS-275183 on HNSCC.

MATERIALS AND METHODS

Head and neck squamous cell carcinoma cell lines, HN6, HN12, and HN30, were exposed to BMS-275183. BMS-275183-induced growth suppression, cell-cycle arrest, and apoptosis were measured. Then, expression of selected proteins that were induced by BMS-275183 was determined by Western blot analysis.

RESULTS

BMS-275183 suppressed proliferation and induced G(2)M arrest and apoptosis in all HNSCC cell lines tested. BMS-275183 altered the expression of cell-cycle regulators, such as cyclin A and cyclin B1. The expression of E2F and p27 was decreased and increased, respectively, in all HNSCC cell lines. Cleaved caspase 3 and poly (ADP-ribose) polymerase (PARP) were increased in HN6 and HN12 cells. epidermal growth factor receptor (EGFR) and mitogen-activated protein kinase (MAPK) expression were decreased by BMS-275183 in HN6 and HN30 cell lines, whereas phosphorylated epidermal growth factor receptor (pEGFR) was decreased in only HN6 cells.

CONCLUSIONS

BMS-275183 induced cellular apoptosis, cell-cycle arrest, and altered gene expression in HNSCC via molecular pathways similar to other taxanes. These preclinical experiments suggest that BMS-275183 may be useful in treating HNSCC and that the aforementioned genes can potentially be used as surrogate end-point biomarkers.

Effect of HER-2/neu overexpression on chemoresistance and prognosis in ovarian carcinoma

AIM

To investigate the effect of HER-2/neu protein overexpression on chemoresistance and prognosis in patients with epithelial ovarian carcinoma.

METHODS

A total of 141 ovarian carcinoma tissues surgically resected between 1987 and 2003 were assessed by immunohistochemistry (IHC). The characteristic of the patients and immunohistochemical results were compared by chi2-test. Survival analysis was performed by the Kaplan-Meier method and the log-rank test.

RESULTS

HER-2/neu overexpression was detected in 18 cases (12.8%). There were no significant differences in histopathological subtypes (P = 0.3550), FIGO stages (P = 0.8858), or residual tumor size at first surgery (P = 0.6607) between the cases with HER-2/neu overexpression and the cases without HER-2/neu overexpression. Among the 58 cases which responded to chemotherapy, only five cases (8.6%) showed HER-2/neu overexpression. However, among the 38 cases which did not respond to chemotherapy, eight cases (21.1%) showed HER-2/neu overexpression. Overexpression of HER-2/neu had a tendency to relate with chemoresistance of epithelial ovarian carcinoma, but there were no statistically significant differences (P = 0.0817). No association was observed between HER-2/neu overexpression and cumulative survival rate (P = 0.4970).

CONCLUSIONS

The results of the current study show that although HER-2/neu overexpression has a tendency to be associated with chemoresistance, it can not be a prognostic factor for the patients with epithelial ovarian carcinoma.

HER2 expression and efficacy of preoperative paclitaxel/FAC chemotherapy in breast cancer

PURPOSE

We examined the correlation between HER2 expression and pathologic complete response (pCR) to paclitaxel/FAC (T/FAC) preoperative chemotherapy in breast cancer.

PATIENTS AND METHODS

Retrospective analysis of data including 534 patients treated with preoperative T/FAC was performed. Gene expression results were available from two datasets of 132 and 286 patients, and were used to examine the co-expression of HER2 and topoisomerase II alpha (TOP2A) and microtubule associated protein tau (MAP-Tau).

RESULTS

Of the 534 patients, 105 (20%) had HER2-overexpressing breast cancer. The pCR rates were 33% and 15% for patients with HER2+ and HER2- tumors (P<0.001). The 5-year relapse-free survival rates were 94% and 70% in HER2+ tumors with and without pCR (P=0.009). HER2 overexpression (odds ratio 2.3, 95%CI: 1.3-3.9, P=0.004), estrogen receptor (ER) status, grade and weekly schedule of paclitaxel were each significantly and independently associated with pCR in multivariate analysis. When patients were stratified by ER status, the pCR rates were 50% for HER2+/ER-, 30% for HER2-/ER-, 19% for HER2+/ER+, and 6% for HER2-/ER+ tumors. HER2 overexpression was associated with lower expression of MAP-tau (P=0.001 and P<0.001) and higher expression of TOP2A mRNAs (P=0.048 and P=0.001) in patients with ER+ disease. ER- cancers had low MAP-tau expression regardless of HER-status.

CONCLUSION

HER2 overexpression is associated with higher rate of pCR to preoperative T/FAC chemotherapy regardless of ER status. HER2 overexpression also correlates with increased TOP2A and decreased MAP-tau expression in ER-positive cancers.

Protein array technology to detect HER2 (erbB-2)-induced 'cytokine signature' in breast cancer

Identification of genes/proteins that are differentially expressed in HER2 (erbB-2) oncogene-dependent breast carcinomas is essential in elucidating the mechanistic basis of their increased metastastic potential and resistance to several anti-cancer therapies. We here applied human cytokine antibody arrays with the goal of identifying a unique HER2-induced 'cytokine signature' in breast cancer. Human Cytokine Array III (RayBiotech, Inc.), which simultaneously detects 42 cytokines and growth factors on one membrane, was used to determine the profile of cytokines in conditioned media obtained from MCF-7/Her2-18 cells, a MCF-7-derived clone engineered to stably express the full-length human HER2 cDNA controlled by a SV40 viral promoter, and from the MCF-7/neo control sub-line. We identified two inflammatory and pro-angiogenic CXC chemokines with at least a 10-fold increased expression in HER2-overexpressing MCF-7/Her2-18 transfectants when compared to matched control MCF-7/neo cells: CXCL8 (IL-8; Interleukin-8) and CXCL1 and (GRO; Growth-related oncogene). HER2-induced differential overexpression of IL-8 and GRO was validated by ELISA and further confirmed by switching off the HER2 signalling. Treatment with the tyrosine kinase inhibitor gefitinib (Iressa) returned the expression levels of IL-8 and GRO back to the baseline observed in MCF-7 breast cancer cells, which express physiological levels of HER2. To evaluate the diagnostic utility of these findings, cytokine-specific antibody arrays were incubated with sera retrospectively collected from metastatic breast cancer patients. This approach revealed a high similarity between the 'cytokine signature' observed in serum samples and that obtained in media conditioned by breast cancer-derived cell lines. Thus, IL-8 and GRO circulating levels were significantly higher in HER2-positive breast cancer patients compared with HER2-negative patients. These findings reveal for the first time that: a) Enhanced synthesis and secretion of members of the IL-8/GRO chemokine family, which have recently been linked to oestrogen receptor (ER) inaction, increased cell invasion and angiogenesis, may represent a new pathway involved in the metastatic progression and endocrine resistance of HER2-overexpressing breast carcinomas, and b) Circulating levels of IL-8 and GRO cytokines may represent novel biomarkers monitoring breast cancer responses to endocrine treatments and/or HER2-targeted therapies.

Phosphorylated HER-2 tyrosine kinase and Her-2/neu gene amplification as predictive factors of response to trastuzumab in patients with HER-2 overexpressing metastatic breast cancer (MBC)

AIM

Trastuzumab (T), a humanised monoclonal antibody against HER-2, is active in HER-2-positive MBC patients. However, nearly 60% of the patients do not benefit from T, stressing the need for additional predictive markers. The following markers could be implicated in response to T: (1) the magnitude of Her-2 gene amplification; (2) the co-expression of the other HER family receptors, possibly responsible for HER-2 trans-activation; (3) the activated status of HER-2; (4) the activated status of downstream effectors as mitogen-activated protein kinases (MAPKs), p38 and p27.

METHODS

Medical files of patients with MBC treated with T either as a single agent or in combination with chemotherapy (CT) were reviewed. HER family members (EGFR, HER-2, HER-3, HER-4), the phosphorylated forms of EGFR (p-EGFR), HER-2 (p-HER-2) and of the downstream effectors were evaluated in the archival tumours. The correlation between clinical outcome and the expression of these markers was investigated.

RESULTS

(1) Increasing values of Her-2 amplification were associated with a higher probability of achieving an objective response; (2) no statistical significant correlation between the expression of the HER family receptors was found; (3) p-HER-2 was predictive of response in patients treated with T+CT; (4) a statistically significant correlation between p-ERK 1/2, p-p38 and p-HER-2 emerged, pointing to the activated vertical pathway p-HER-2-->p-MAPKs.

CONCLUSIONS

p-HER-2 and the magnitude of Her-2 amplification were predictive of response to T and their role deserves to be analysed in larger and more homogenous T-treated populations such as those from large phase III trials.

5-FdUrd-araC heterodinucleoside re-establishes sensitivity in 5-FdUrd- and AraC-resistant MCF-7 breast cancer cells overexpressing ErbB2

ErbB2 overexpressing breast tumors have a poor prognosis and a high risk to develop chemoresistance to therapeutic treatment. "Chemoresistance" is a response of cells to toxic stress, and, although it is a common phenomenon, it is still poorly defined. However, a detailed understanding is required to target desensitized pathways and mechanisms for successful reactivation as part of a tailored therapy. To gain insight, which malfunctions contribute to chemoresistance, two mechanisms relevant for tissue homeostasis, the regulation of the cell cycle and of apoptosis, were investigated. Maternal MCF-7- and ErbB2-overexpressing MCF-7(erbB2) breast cancer cells were long term pretreated with 2'-deoxy-5-fluorodeoxyuridine (5-FdUrd) or 1-beta-d-arabinofuranosylcytosine (AraC) and the acquisition of drug-insensitivity was analyzed. A phosphate-conjugated heterodinucleoside consisting of one 5-FdUrd- and one AraC-moiety (5-fluoro-2'-desoxyuridylyl-(3'-->5')-Arabinocytidine) was utilized as a tool to assess the type of acquired resistances. ErbB2-overexpression disrupted proper cell cycle regulation and furthermore facilitated the development of an apoptosis-refractory phenotype upon exposure to 5-FdUrd. Experiments with dimer 5-FdUrd-araC in ErbB2-overexpressing MCF-7(erbB2) cells, and also with nucleoside 5-FdUrd in maternal MCF-7 cells, evidenced that the phenotypes of resistance to cell cycle inhibition and to apoptosis induction were differently affected. The expression profile of cyclin D1 (but not that of p53, p21, or p27) correlated with the proliferative phenotypes and nuclear accumulation of apoptosis inducing factor (but not activation of caspase 7) with apoptotic phenotypes. Dimer 5-FdUrd-araC overrode acquired chemoresistances, whereas combined application of 5-FdUrd and AraC exhibited significantly less activity. Dimer 5-FdUrd-araC remained active in MCF-7 clones most likely by circumventing the prerequisite of first-step phosphorylation. The acquisition of chemoresistance encompassed the affection of apoptosis- and cell-cycle regulation to, respectively, different extents. Thus, drug-induced cell cycle arrest and apoptosis induction are independent of each other.

Peptide Aptamers with Binding Specificity for the Intracellular Domain of the ErbB2 Receptor Interfere with AKT Signaling and Sensitize Breast Cancer Cells to Taxol

The ErbB2 receptor tyrosine kinase is overexpressed in approximately 30% of breast tumor cases and its overexpression correlates with an unfavorable prognosis. A major contributor for this course of the disease is the insensitivity of these tumors toward chemotherapy. Monoclonal antibodies, inhibiting the ligand-induced activation of the receptor and tyrosine kinase inhibitors acting on the intrinsic enzymatic activity of the intracellular domain, have been developed as targeted drugs. Both have been shown to be beneficial for breast cancer patients. We targeted a third aspect of receptor function: its association with intracellular signaling components. For this purpose, we selected peptide aptamers, which specifically interact with defined domains of the intracellular part of the receptor. The peptide aptamers were selected from a random peptide library using a yeast two-hybrid system with the intracellular tyrosine kinase domain of ErbB2 as a bait construct. The peptide aptamer AII-7 interacts with high specificity with the ErbB2 receptor in vitro and in vivo. The aptamers colocalized with the intracellular domain of ErbB2 within cells. We investigated the functional consequences of the aptamer interaction with the ErbB2 receptor within tumor cells. The aptamer sequences were either expressed intracellularly or introduced into the cells as recombinant aptamer proteins. The phosphorylation of p42/44 mitogen-activated protein kinase was nearly unaffected and the activation of signal transducers and activators of transcription-3 was only modestly reduced. In contrast, they strongly inhibited the induction of AKT kinase in MCF7 breast cancer cells treated with heregulin, whereas AKT activation downstream of insulin-like growth factor I or epidermal growth factor receptor was not or only slightly affected. High AKT activity is responsible for the enhanced resistance of ErbB2-overexpressing cancer cells toward chemotherapeutic agents. Peptide aptamer interference with AKT activation resulted in the restoration of regular sensitivity of breast cancer cells toward Taxol.

Trastuzumab in Combination With Heregulin-Activated Her-2 (erbB-2) Triggers a Receptor-Enhanced Chemosensitivity Effect in the Absence of Her-2 Overexpression

Purpose

The decision for treating breast cancer patients with trastuzumab is based on HER-2 amplification and/or overexpression.

Methods

Using MCF-7 cells (Her-2 ±) engineered to overexpress heregulin (MCF-7/HRG), a ligand for the Her-2/3/4 network, we investigated whether HRG-induced transactivation of Her-2 affected breast cancer cell sensitivity to chemotherapy and whether trastuzumab trigger receptor-enhanced chemosensitivity (REC) when combined with chemotherapy without Her-2 overexpression.

Results

MCF-7/HRG cells were more than 10-fold resistant to the alkylating agent cisplatin (CDDP), while trastuzumab coexposure completely reversed HRG-promoted CDDP resistance. A synergistic interaction between trastuzumab in combination with CDDP (paclitaxel or vincristine) was obtained in MCF-7/HRG cells. Trastuzumab prevented activation of the antiapoptotic and proliferative cascades and inhibited HRG-induced Her-2/3 phosphorylation. CDDP efficacy was enhanced by trastuzumab in cells expressing endogenously high levels of HRG. Conversely, trastuzumab coexposure was ineffective in enhancing chemotherapy efficacy in cells that did not secrete HRG, such as MCF-7 cells overexpressing a structural mutated HRG isoform. Therefore, trastuzumab-induced REC, in the absence of Her-2 overexpression, occurs through the kinase activity of Her-2/3. Interestingly, HRG expression in tumor biopsies from invasive breast carcinomas (n = 189) revealed that, whereas the minority (12%) of Her-2 positive tumors (n = 60; 32%) demonstrated Her-2 phosphorylation, the majority (67%) of HRG-overexpressing and Her-2 tumors (n = 57; 30%) were in active Her-2 status.

Conclusion

We demonstrate that assessment of HRG expression and Her-2 activation define a particular breast cancer patient population for which trastuzumab plus CDDP or taxol are extremely efficient without Her-2 overexpression.

ERBB2-mediated transcriptional up-regulation of the alpha5beta1 integrin fibronectin receptor promotes tumor cell survival under adverse conditions

Oncogenic activation of the receptor tyrosine kinase ERBB2 is a key event in the development of a number of epithelial malignancies. In these tumors, high levels of ERBB2 are strongly associated with metastatic disease and poor prognosis. Paradoxically, an inherent cellular response to hypermitogenic signaling by ERBB2 and other oncogenes seems to be growth arrest, rather than proliferation. Molecular characterization of this yet undefined antiproliferative state in independent cell lines overexpressing either wild-type ERBB2 or the mutationally activated receptor unveiled a dramatic induction of the alpha5beta1 integrin fibronectin receptor. alpha5 Integrin up-regulation is mainly a transcriptional response mediated by the hypoxia-inducible transcription factors (HIF), leading to a massive increase in membrane-resident receptor molecules and enhanced fibronectin adhesiveness of the respective cells. Functionally, ERBB2-dependent ligation of fibronectin results in improved survival of mammary adenocarcinoma cells under adverse conditions, like serum withdrawal, hypoxia, and chemotherapy. HIF-1alpha is an independent predictor of poor overall survival in patients with breast cancer. In particular, HIF-1alpha overexpression correlates significantly with early local relapse and distant metastasis, a phenotype also highly characteristic of ERBB2-positive tumors. As HIF-1alpha is known to be stabilized by ERBB2 signaling under normoxic conditions, we propose that alpha5 integrin is a major effector in this regulatory circuit and may represent the molecular basis for the HIF-1alpha-dependent aggressiveness observed in ERBB2-overexpressing breast carcinomas. Hypermitogenic ERBB2 signaling and tumor hypoxia may act synergistically to favor the establishment of chemoresistant dormant micrometastatic cells frequently observed in patients with breast cancer. This new insight could be the basis for additional approaches complementing current cancer therapy.

Selective Inhibition of ErbB2-Overexpressing Breast Cancer In vivo by a Novel TAT-Based ErbB2-Targeting Signal Transducers and Activators of Transcription 3–Blocking Peptide

ErbB2 is an excellent target for cancer therapies. Unfortunately, the outcome of current therapies for ErbB2-positive breast cancers remains unsatisfying due to resistance and side effects. New therapies for ErbB2-overexpressing breast cancers continue to be in great need. Peptide therapy using cell-penetrating peptides (CPP) as peptide carriers is promising because the internalization is highly efficient, and the cargoes delivered can be bioactive. However, the major obstacle in using these powerful CPPs for therapy is their lack of specificity. Here, we sought to develop a peptide carrier that could introduce therapeutics specifically to ErbB2-overexpressing breast cancer cells. By modifying the HIV TAT-derived CPP and conjugating anti-HER-2/neu peptide mimetic (AHNP), we developed the peptide carrier (P3-AHNP) that specifically targeted ErbB2-overexpressing breast cancer cells in vitro and in vivo. A signal transducers and activators of transcription 3 (STAT3)-inhibiting peptide conjugated to this peptide carrier (P3-AHNP-STAT3BP) was delivered more efficiently into ErbB2-overexpressing than ErbB2 low-expressing cancer cells in vitro and successfully decreased STAT3 binding to STAT3-interacting DNA sequence. P3-AHNP-STAT3BP inhibited cell growth in vitro, with ErbB2-overexpressing 435.eB breast cancer cells being more sensitive to the treatment than the ErbB2 low-expressing MDA-MB-435 cells. Compared with ErbB2 low-expressing MDA-MB-435 xenografts, i.p. injected P3-AHNP-STAT3BP preferentially accumulated in 435.eB xenografts, which led to more reduction of proliferation and increased apoptosis and targeted inhibition of tumor growth. This novel peptide delivery system provided a sound basis for the future development of safe and effective new-generation therapeutics to cancer-specific molecular targets.

Prediction of anticancer drug potency from expression of genes involved in growth factor signaling

PURPOSE

This study develops and evaluates a systematic approach to finding biomarker genes for predicting potency of anticancer drugs against tumor cells, focusing on gene families related to growth factor signaling.

METHODS

Cytotoxic potencies of 119 drugs against 60 neoplastic cell lines (NCI-60) were correlated with expression of 343 genes, including 90 growth factors and receptors, 63 metalloproteinases, and 92 ras-like GTPases as downstream signaling factors. Progressively more stringent criteria and predictive models aim at identifying the smallest subset of genes predictive of cytotoxic potency.

RESULTS

Comparing gene expression with drug potency across the NCI-60 yielded genes with negative and positive correlations (p < 0.001), indicative of a role in chemoresistance and chemosensitivity, respectively. Of 17 genes with multiple negative correlations, 8 are known chemoresistance factors, validating the approach. Negatively correlated genes clustered into two main groups with distinct expression profiles and drug correlations, represented by EGFR and ERBB2 (Her-2/Neu). Accordingly, no synergism was observed between EGFR and ERBB2 inhibitors. However, combinations with classical anticacer drugs were not correlated with EGFR and ERBB2 expression in four cell lines tested, suggesting complex interactions in combination treatments. Finally, a subset of only 13 genes was found to be sufficient for near optimal prediction of drug potency against the NCI-60.

CONCLUSIONS

Our approach using a small subset of genes reveals known and potential biomarkers in cancer chemotherapy, providing a strategy for genome-wide analysis.

A genomic explanation connecting "Mediterranean diet", olive oil and cancer: oleic acid, the main monounsaturated fatty acid of olive oil, induces formation of inhibitory "PEA3 transcription factor-PEA3 DNA binding site" complexes at the Her-2/neu (erbB-2) oncogene promoter in breast, ovarian and stomach cancer cells

Olive oil is an integral ingredient of the "Mediterranean diet" and accumulating evidence suggests that it may have a potential role in lowering risk of several cancers. We recently hypothesized that the anti-cancer actions of olive oil may relate to its monounsaturated fatty acid (MUFA) oleic acid (OA; 18:1n-9) content to specifically regulate oncogenes. In this study, transient transfection experiments with human Her-2/neu promoter-driven luciferase gene established the ability of OA to specifically repress the transcriptional activity of Her-2/neu gene. Gene repression was seen in tumour-derived cell lines with Her-2/neu gene amplification and overexpression, including SK-Br3 (56% reduction), SK-OV3 (75% reduction) and NCI-N87 (55% reduction) breast, ovarian and stomach cancer cell lines, respectively. Also marginal decreases in promoter activity were observed in cancer cells expressing physiological levels of Her-2/neu (20% reduction in MCF-7 breast cancer cells). Remarkably, OA treatment in Her-2/neu-overexpressing cancer cells was found to induce up-regulation of the Ets protein polyomavirus enhancer activator 3 (PEA3), a transcriptional repressor of Her-2/neu promoter. Also, an intact PEA3 DNA-binding-site at endogenous Her-2/neu gene promoter was essential for OA-induced repression of this gene. Moreover, OA treatment failed to decrease Her-2/neu protein levels in MCF-7/Her2-18 transfectants, which stably express full-length human Her-2/neu cDNA controlled by a SV40 viral promoter. OA-induced transcriptional repression of Her-2/neu through the action of PEA3 protein at the promoter level may represent a novel mechanism linking "Mediterranean diet" and cancer.

The ErbB2 signaling network as a target for breast cancer therapy

Overexpression of the ErbB2/Her2 receptor tyrosine kinase in breast cancers is associated with the most aggressive tumors. Experimental studies have revealed that ErbB2 shows many features of a therapeutic target: ErbB2 is able to confer many of the characteristics of a cancerous cell, including uncontrolled proliferation, resistance to apoptosis and increased motility; ErbB2 overexpression is specific to tumor cells; as a cell surface-associated protein, it is easily accessible to drugs and as a kinase it is amenable to targeted inhibition by small molecules. Recent clinical results demonstrate the efficacy of ErbB2-targeting therapy and promise an expanding use of ErbB2-targeting drugs for breast cancer treatment. However, as only a fraction of patients responds successfully to therapy and risks of recurrence are still high, further investigation is required for an improved understanding of the complex network of signaling pathways underlying ErbB2-driven cancer progression.

Effect of gamma-linolenic acid on the transcriptional activity of the Her-2/neu (erbB-2) oncogene

The omega-6 polyunsaturated fatty acid gamma-linolenic acid (GLA; 18:3n-6), which is found in several plant oils and is used as an herbal medicine, has antitumor activity in vitro. We examined the effect of GLA on the expression of the Her-2/neu (erbB-2) oncogene, which is involved in development of numerous types of human cancer. Flow cytometric and immunoblotting analyses demonstrated that GLA treatment substantially reduced Her-2/neu protein levels in the Her-2/neu-overexpressing cell lines BT-474, SK-Br3, and MDA-MB-453 (breast cancer), SK-OV3 (ovarian cancer), and NCI-N87 (gastrointestinal tumor derived). GLA exposure led to a dramatic decrease in Her-2/neu promoter activity and a concomitant increase in the levels of polyomavirus enhancer activator 3 (PEA3), a transcriptional repressor of Her-2/neu, in these cell lines. In transient transfection experiments, a Her-2/neu promoter bearing a PEA3 site-mutated sequence was not subject to negative regulation by GLA in Her-2/neu-overexpressing cell lines. Concurrent treatments of Her-2/neu-overexpressing cancer cells with GLA and the anti-Her-2/neu antibody trastuzumab led to synergistic increases in apoptosis and reduced growth and colony formation.

Gefitinib is more effective in never-smokers with non-small-cell lung cancer: experience among Asian patients

We retrospectively analysed the results of patients with advanced non-small-cell lung cancer treated with gefitinib to derive clinical factors predictive of response and a favourable survival outcome. Patients were treated with gefitinib 250 mg per day and re-evaluated 4–8 weeks later with repeat CT scan and every 8 weeks thereafter to assess response and the duration of response. Pathology review by a histopathologist was conducted, in particular to confirm a recently published result of bronchioloalveolar carcinoma histology or its components as predictive of response to gefitinib. Logistic regression and Cox regression analytical methods were applied to determine factors that could predict for response and improved overall survival. A total of 110 patients were treated. The overall response rate was 32% partial responses (PRs). Only never-smoking status was predictive of response in the logistic regression analysis, adjusted OR=6.1, 95% CI=1.7, 21.5. The presence of a PR and good performance status were predictive of a favourable survival outcome from the Cox regression modelling. Responders had an adjusted HR of 3.0, 95% CI=1.5–5.8 compared to nonresponders, while patients with ECOG status 0–1 had an adjusted HR of 0.42, 95% CI=0.25–0.72, compared with patients with ECOG status 2–4. Bronchioloalveolar carcinoma or its components were distinctly absent on pathology review. In conclusions, Never-smoking status is an important clinical predictor of a favourable response to gefitinib.

The immunocytokine scFv23/TNF sensitizes HER-2/neu–overexpressing SKBR-3 cells to tumor necrosis factor (TNF) via up-regulation of TNF receptor-1

Overexpression of HER-2/neu confers cellular resistance to tumor necrosis factor (TNF)-mediated cytotoxicity to SKBR-3 breast cancer cell lines. To understand the correlation between HER-2/neu expression and TNF resistance, we examined the unique signaling pathways associated with the cytotoxic effects of the immunocytokine scFv23/TNF, recombinant single-chain antibody fusion constructs containing TNF and targeting HER-2/neu, in TNF-resistant SKBR-3-LP cells. We found that treatment of HER-2/neu-overexpressing SKBR-3-LP cells with scFv23/TNF resulted in a 5- to 7-fold higher level of TNF receptor-1 expression 48 hours after exposure. In addition, treatment of SKBR-3-LP cells with scFv23/TNF resulted in down-regulation of Akt phosphorylation and induced apoptosis through cleavage of caspase-8, caspase-3, and poly(ADP-ribose) polymerase. ScFv23/TNF-induced cytotoxicity was inhibited by blocking of the binding of the TNF component of scFv23/TNF to TNF receptor-1 and was dependent on activation of caspase-8 and caspase-3. These results indicate that the immunocytokine scFv23/TNF sensitizes TNF-resistant HER-2/neu-overexpressing SKBR-3-LP cells to TNF-induced apoptosis via the overexpression of TNF receptor-1 and suggest that the overexpression of TNF receptor-1 plays a crucial role in TNF sensitivity in HER-2/neu-overexpressing cancer cells. ScFv23/TNF targeting the HER-2/neu may be an effective cytotoxic agent against HER-2/neu-overexpressing cancer cells, which are inherently resistant to TNF.