FeSe quantum dots for in vivo multiphoton biomedical imaging

An immense demand in biomedical imaging is to develop efficient photoluminescent probes with high biocompatibility and quantum yield, as well as multiphoton absorption performance to improve penetration depth and spatial resolution. Here, iron selenide (FeSe) quantum dots (QDs) are reported to meet these criteria. The synthesized QDs exhibit two- and three-photon excitation property at 800- and 1080-nm wavelengths and high quantum yield (ca. 40%), which are suitable for second-window imaging. To verify their biosuitability, poly(ethylene glycol)-conjugated QDs were linked with human epidermal growth factor receptor 2 (HER2) antibodies for in vitro/in vivo two-photon imaging in HER2-overexpressed MCF7 cells and a xenograft breast tumor model in mice. Imaging was successfully carried out at a depth of up to 500 μm from the skin using a nonlinear femtosecond laser at an excitation wavelength of 800 nm. These findings may open up a way to apply biocompatible FeSe QDs to multiphoton cancer imaging.

Abnormal Anionic Porphyrin Sensing Effect for HER2 Gene Related DNA Detection via Impedance Difference between MWCNTs and Single-Stranded DNA or Double-Stranded DNA

Human epidermal growth factor receptor 2 (HER2) is a key tumor marker for several common and deadly cancers. It is of great importance to develop efficient detection methods for its over-expression. In this work, an electrochemical impedance spectroscopy (EIS) method adjustable by anionic porphyrin for HER2 gene detection has been proposed, based on the impedance difference between multi-walled carbon nanotubes (MWCNTs) and DNA. The interesting finding herein is that with the addition of anionic porphyrin, i.e., meso-tetra(4-sulfophenyl)-porphyrin (TSPP), the impedance value obtained at a glass carbon electrode (GCE) modified with MWCNTs and a single stranded DNA (ssDNA), the probe DNA that might be assembled tightly onto MWCNTs through π-π stacking interaction, gets a slight decrease; however, the impedance value from a GCE modified with MWCNTs and a double stranded DNA (dsDNA), the hybrid of the probe DNA with a target DNA, which might be assembled loosely onto MWCNTs for the screening effect of phosphate backbones in dsDNA, gets an obvious decrease. The reason may be that on the one hand, being rich in negative sulfonate groups, TSPP will try to push DNA far away from CNTs surface due to its strong electrostatic repulsion towards DNA; on the other hand, rich in planar phenyl or pyrrole rings, TSPP will compete with DNA for the surface of CNTs since it can also be assembled onto CNTs through conjugative interactions. In this way, the “loosely assembled” dsDNA will be repelled by this anionic porphyrin and released off CNTs surface much more than the “tightly assembled” ssDNA, leading to a bigger difference in the impedance value between dsDNA and ssDNA. Thus, through the amplification effect of TSPP on the impedance difference, the perfectly matched target DNA could be easily determined by EIS without any label. Under the optimized experimental conditions, this electrochemical sensor shows an excellent linear response to target DNA in a concentration range of 2.0 × 10⁻¹¹–2.0 × 10⁻⁶ M with a limit of detection (LOD) of 6.34 × 10⁻¹¹ M (S/N = 3). This abnormally sensitive electrochemical sensing performance resulting from anionic porphyrin for DNA sequences specific to HER2 gene will offer considerable promise for tumor diagnosis and treatment.

The real-world cost-effectiveness of adjuvant trastuzumab in HER-2/neu-positive early breast cancer in Taiwan

BACKGROUND

Trastuzumab was considered a cost-effective adjuvant treatment for HER 2-positive early breast cancer. Since 2010, the Taiwanese National Health Insurance (NHI) has started to reimburse for 1-year adjuvant treatment. This study aims to provide an updated cost-effectiveness analysis from the NHI perspective, which explores assumptions about long-term cardiac toxicity and treatment benefit of 1-year adjuvant treatment sequentially after chemotherapy.

METHODS

A Markov model was used to evaluate the cost-effectiveness of 1-year adjuvant trastuzumab for HER-2/neu positive early breast cancer over a 20-year life-time horizon. A probability sensitivity analysis using Monte Carlo simulation was performed to characterize uncertainties in the expected outcomes, which are expressed as an incremental costs effectiveness ratio (ICER, cost/QALY). A willingness-to-pay threshold of 3-times the per capita gross domestic product was adopted according to the WHO definition. The Taiwan per capita gross domestic product in 2015 was US$22,355; thus, a threshold was considered as NT$2,011,950 (US$67 065, 1USD =30 NTD in 2015).

RESULTS

The model showed that adjuvant trastuzumab treatment in HER-2/neu positive early breast cancer yielded 1.631 quality-adjusted life-years (QALY) compared with no trastuzumab treatment. The ICER was US $51,863 per QALY gained in the base-case scenario. The Monte Carlo simulation by varying all variables simultaneously demonstrated that the probability of cost-effectiveness at the willingness-to-pay threshold of US$67,065 was 50% for 1-year adjuvant trastuzumab.

CONCLUSIONS

From this real-world study, 1-year adjuvant trastuzumab treatment is likely to be a cost-effective therapy for patients with HER-2 positive breast cancer at the willingness-to-pay threshold of 3-times GDP per capita in Taiwan.

The rat ErbB2 tyrosine kinase receptor produced in plants is immunogenic in mice and confers protective immunity against ErbB2(+) mammary cancer

The rat ErbB2 (rErbB2) protein is a 185-kDa glycoprotein belonging to the epidermal growth factor-related proteins (ErbB) of receptor tyrosine kinases. Overexpression and mutations of ErbB proteins lead to several malignancies including breast, lung, pancreatic, bladder and ovary carcinomas. ErbB2 is immunogenic and is an ideal candidate for cancer immunotherapy. We investigated the possibility of expressing the extracellular (EC) domain of rErbB2 (653 amino acids, aa) in Nicotiana benthamiana plants, testing the influence of the 23 aa transmembrane (TM) sequence on protein accumulation. Synthetic variants of the rErbB2 gene portion encoding the EC domain, optimized with a human codon usage and either linked to the full TM domain (rErbB2_TM, 676 aa), to a portion of it (rErbB2-pTM, 662 aa), or deprived of it (rErbB2_noTM, 653 aa) were cloned in the pEAQ-HT expression vector as 6X His tag fusions. All rErbB2 variants (72-74.5 kDa) were transiently expressed, but the TM was detrimental for rErbB2 EC accumulation. rERbB2_noTM was the most expressed protein; it was solubilized and purified with Nickel affinity resin. When crude soluble extracts expressing rErbB2_noTM were administered to BALB/c mice, specific rErbB2 immune responses were triggered. A potent antitumour activity was induced when vaccinated mice were challenged with syngeneic transplantable ErbB2(+) mammary carcinoma cells. To our knowledge, this is the first report of expression of rErbB2 in plants and of its efficacy in inducing a protective antitumour immune response, opening interesting perspectives for further immunological testing.

Breast Cancer Subtype is Associated With Axillary Lymph Node Metastasis: A Retrospective Cohort Study

The purpose of this study was to assess whether breast cancer subtype (BCS) as determined by estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 can predict the axillary lymph node metastasis in breast cancer. Patients who received breast conserving surgery or mastectomy and axillary lymph node dissection were identified from 2 cancer centers. The associations between clinicopathological variables and axillary lymph node involvement were evaluated in univariate and multivariate regression analyses. A total of 3471 patients met the inclusion criteria, and 53.0% had axillary lymph node metastases at diagnosis. Patients with hormone receptor (HR)-/human epidermal growth factor receptor 2 (HER2)- subtype had a higher grade disease and the lowest rate of lymphovascular invasion. Univariate and multivariable logistic regression analyses showed that BCS was significantly associated with lymph node involvement. Patients with the HR-/HER2- subtype had the lowest odds of having nodal positivity than those with other BCSs. HR+/HER2- (odds ratio [OR] 1.651, 95% confidence interval [CI]: 1.349-2.021, P < 0.001), HR+/HER2+ (OR 1.958, 95%CI 1.542-2.486, P < 0.001), and HR-/HER2+ (OR 1.525, 95%CI 1.181-1.970, P < 0.001) tumors had higher risk of nodal positivity than the HR-/HER2- subtype. The other independent predictors of nodal metastases included tumor size, tumor grade, and lymphovascular invasion. Breast cancer subtype can predict the presence of axillary lymph node metastasis in breast cancer. HR-/HER2- is associated with a reduced risk of axillary lymph node metastasis compared to other BCSs. Our findings may play an important role in guiding axillary treatment considerations if further confirmed in larger sample size studies.

[Immunocytochemical visualization of P185(HER2) receptor by antibody fused with dibarnase and conjugate of barstar with colloidal gold]

We studied the localization of transmembrane receptor P185(HER2) in SKOV-3 and BT-474 cancer cells by fluorescence, confocal and electron immunomicroscopy. P185(HER2) is a marker of breast and ovarian tumors, it is considered as a target for anticancer therapy. It is extremely important to choose a universal immunicytotoxic agent applicable, first, to study the distribution of P185(HER2) in cancer cells, secondly, to remove P185(HER2) from the cell surface and, thirdly, to eliminate target cells. In this work for visualization of P185HER2 We prOposed immunocytotoxic system, consisting of the monoclonal miniantibody 4D5 scFv to extracellular P185E domain fused with two molecules of barnase (ribonuclease from Bacillus amyloliquefaciens) and of its specific inhibitor barstar. Fluorescence microscopy has showed that the module 4D5 scFv-dibarnase:barstar efficiently identified P185(HER2) on the surface of cancer cells. It was revealed by confocal microscopy that interaction with 4D5 scFv-dibarnase lead to internalization of P185(HER2). The localization of P185(HER) in human ovarian carcinoma cells SKOV-3 and breast carcinoma cells BT-474 was compared by electron microscopy using 4D5 scFv-dibarnase:barstar-Au and 4D5 scFv-dibarnase-Au complexes. P185(HER) distributed on the cell surface unequally with preferential localization on protrusions or close to their bases and in contacts between protrusions and cell membrane. At 37 degrees C, P185(HER2) internalized through coated pits and vesicles and concentrated in the endosomes and multivesicular bodies in the cells of both cell lines, as well as in lysosomes in cells BT-474.

Application of selected reaction monitoring for multiplex quantification of clinically validated biomarkers in formalin-fixed, paraffin-embedded tumor tissue

One of the critical gaps in the clinical diagnostic space is the lack of quantitative proteomic methods for use on formalin-fixed, paraffin-embedded (FFPE) tissue. Herein, we describe the development of a quantitative, multiplexed, mass spectrometry-based selected reaction monitoring (SRM) assay for four therapeutically important targets: epidermal growth factor receptor, human EGF receptor (HER)-2, HER3, and insulin-like growth factor-1 receptor. These assays were developed using the Liquid Tissue-SRM technology platform, in which FFPE tumor tissues were microdissected, completely solubilized, and then subjected to multiplexed quantitation by SRM mass spectrometry. The assays were preclinically validated by comparing Liquid Tissue-SRM quantitation of FFPE cell lines with enzyme-linked immunosorbent assay/electrochemiluminescence quantitation of fresh cells (R(2) > 0.95). Clinical performance was assessed on two cohorts of breast cancer tissue: one cohort of 10 samples with a wide range of HER2 expression and a second cohort of 19 HER2 IHC 3+ tissues. These clinical data demonstrate the feasibility of quantitative, multiplexed clinical analysis of proteomic markers in FFPE tissue. Our findings represent a significant advancement in cancer tissue analysis because multiplexed, quantitative analysis of protein targets in FFPE tumor tissue can be tailored to specific oncological indications to provide the following: i) complementary support for anatomical pathological diagnoses, ii) patient stratification to optimize treatment outcomes and identify drug resistance, and iii) support for the clinical development of novel therapies.

[Bacterial synthesis, purification, and solubilization of transmembrane segments of ErbB family members]

A family of epidermal growth factor receptors, ErbB, represents an important class of receptor tyrosine kinases, playing a leading role in cellular growth, development and differentiation. Transmembrane domains of these receptors transduce biochemical signals across plasma membrane via lateral homo- and heterodimerization. Relatively small size of complexes of ErbB transmembrane domains with detergents or lipids allows one to study their detailed spatial structure using three-dimensional heteronuclear high-resolution NMR spectroscopy. Here, we describe the effective expression system and purification procedure for preparative-scale production of transmembrane peptides from four representatives of ErbB family, ErbB1, ErbB2, ErbB3, ErbB4, for structural studies. The recombinant peptides were produced in Escherichia coli BL21(DE3)pLysS as C-terminal extensions of thioredoxin A. The fusion protein cleavage was accomplished with the light subunit of human enterokinase. Several (10-30) milligrams of purified isotope-labeled transmembrane peptides were isolated with the use of a simple and convenient procedure, which consists of consecutive steps of immobilized metal affinity chromatography and cation-exchange chromatography. The purified peptides were reconstituted in lipid/detergent environment (micelles or bicelles) and characterized using dynamic light scattering, CD and NMR spectroscopy. The data obtained indicate that the purified ErbB transmembrane peptides are suitable for structural and dynamic studies of their homo- and heterodimer complexes using high resolution NMR spectroscopy.

Purification of a non-tagged recombinant BCG heat shock protein 65-Her2 peptide fusion protein from Escherichia coli

Bacille Calmette-Guerin (BCG)-derived heat shock protein 65 (HSP65) has been demonstrated capable of assisting a fused peptide to generate the peptide-specific cellular immunity. Various HSP65 fusion proteins have been developed as therapeutic cancer vaccines. Purifying a recombinant HSP65 fusion protein with no purification tags for human use is routinely a challenge. Here, we report a scheme for purifying a non-tagged recombinant HSP65-Her2 peptide fusion protein (HSP65-Her2) from Escherichia coli. The HSP65-Her2 is being developed as an immunotherapeutic for the treatment of Her2-positive tumors. After fermentation in a 10-L fermentor, the HSP65-Her2 expressing E. coli were harvested and lysed by sonication. The recombinant HSP65-Her2 was then purified with four successive steps including Butyl-Sepharose FF, DEAE-Sepharose FF, 1% Triton X-114 phase separation and Sephadex G-25. Results showed that HSP65-Her2 was purified up to 97% purity and was able to generate Her2-specific cytotoxic T lymphocytes (CTLs), suggesting that the scheme is efficient for purifying the non-tagged HSP65-Her2 fusion protein with biological activity.

Purification and characterization of recombinant extracellular domain of human HER2 from Escherichia coli

The human epidermal growth factor receptor 2 (HER2) is a member of the epidermal growth factor receptor (EGFR) family, and it plays an important role in the development of many human adenocarcinomas. The extracellular domain (ECD) of HER2 is an ideal target for therapeutic approaches. In order to obtain large quantities of active HER2 ECD protein for biochemical and structural analysis and for detecting anti-HER2 ECD antibodies in serum, a systematic assessment of optimal parameters for the refolding of the glutathione S-transferase (GST) fusion protein was carried out. After the GST-HER2 ECD inclusion bodies were solubilized with denaturation buffer containing 8M urea, an approach was then used to optimize refolding parameters. This approach utilized dilution of denatured and reduced GST-HER2 ECD into different refolding buffers using orthogonal design method. Optimal refolding was obtained in an alkaline buffer containing reduced and oxidized glutathione, and subsequent incubation at 4 degrees C for 24h. After purification with glutathione Sepharose 4B and PreScission protease cleavage of the fusion protein, 8.9mg of recombinant HER2 ECD was obtained from 1L of Escherichia coli. Rabbit polyclonal antibodies against HER2 ECD were obtained. The purified protein was found to be immunogenic and useful for immunodiagnostic studies of serum HER2 ECD and its antibodies by using enzyme-linked immunosorbent assay (ELISA).

Surface plasmon resonance investigations of human epidermal growth factor receptor 2

This investigation utilizes surface plasmon resonance (SPR) spectroscopy to detect and quantify human epidermal growth factor receptor 2 (HER-2), an oncogene product that is over-expressed in some aggressive forms of breast cancer. Specifically, the HER-2 trans-membrane protein p185 and its extra cellular fragment p105 are analytes targeted in this work by using a gold-based biosensor slide on which an anti-HER-2 antibody has been immobilized by attachment to Protein G that is fixed to the gold film. A detection limit of > or =11 ng/mL for p185 resulted when trastuzumab was used as the anti-HER-2 antibody on the biosensor slide. Experiments with semi-purified p105 revealed that it binds weakly and reversibly to trastuzumab, therefore complicating its detection and quantification. Results of studies that reacted a 13-amino-acid peptide (PP13) from the HER-2 kinase domain with its specific antibody were critically different than p185 and p105 studies. Spectral analysis of the reflectivity at constant bulk buffer refractive index revealed a progressive negative SPR shift over time. A negative shift suggests that a loss of protein mass from the anti-PP13 antibody-Protein G biosensor is occurring. Several possibilities that may explain these negative SPR shifts are discussed.

A targeted proteomic approach for the identification of tumor-associated membrane antigens using the ProteomeLab PF-2D in tandem with mass spectrometry

Mapping differential expression of soluble proteins has become fairly routine using chromatofocusing in combination with the reversed-phase HPLC (ProteomeLab PF-2D by Beckman Coulter Inc.); however, identification of membrane antigens has not been reported thus far. In this report, we demonstrate a targeted proteomic approach employing immunoprecipitation, prior to 2D-LC separation, in tandem with MS/MS that can be used to identify tumor-associated membrane antigens. This system is very sensitive and reproducible in that only 1/4th the amount of starting material is required for analysis as compared to gel-based analysis, and permits a focused environment for eliminating non-specific interactions leading to an accurate resolution of the cognate antigen. This system also circumvents the well-known limitations associated with gel-based approaches. This approach has been validated in the identification of ErB2/HER-2 and was subsequently used to identify CD44E as the cognate antigen for VB1-008, one of our fully human, tumor-specific, monoclonal antibodies.

Purification, characterization and biological significance of tumor-derived exosomes

Exosomes are nanovesicles that are released into the extracellular environment during the fusion of multivesicular bodies with the plasma membrane. Exosomes released from dendritic cells, dexosomes, have several biological functions, for example as immunostimulants. Some tumor cells also secrete exosomes (Tu-exosomes). Although experimental data obtained with the use of dexosomes suggest a biological function of Tu-exosomes, this still remains poorly understood. To examine the function of Tu-exosomes, we established a method for collecting highly purified Tu-exosomes, using paramagnetic beads coated with antibodies against tumor-specific proteins such as HER2/neu. With these antibody-coated beads (Ab-beads), it was possible to collect HER2-expressing Tu-exosomes of high purity. Tu-exosomes were also collected from malignant ascites, which contain exosomes secreted from various types of cells such as tumor cells, lymphoid cells and mesothelial cells. The isolation of Tu-exosomes was confirmed by FACS analysis. With regard to their biological functions, Tu-exosomes cultured with a human breast cancer cell line bound to the cell surface and increased tumor cell proliferation. These data indicate that Tu-exosomes may have physiological functions.

Serum p53 antibodies in correlation to other biological parameters of breast cancer

Breast cancer is the second most frequent cancer of Thai women. Mutation of p53 is a common event in breast cancer. This alteration can result in cellular accumulation of p53 and may also found in serum p53 antibodies (p53-Abs). To clarify prognostic significance of these antibodies, we evaluated p53-Abs in 158 sera of patients with breast cancer. Thirty (19%) patients were found to have p53-Abs. The incidence of p53-Abs tended to be higher in patients with advanced disease group (stages III and IV) than patients with early disease group (stages I and II) (P=0.055). Strong correlations were found between the presence of p53-Abs and p53 protein expression (P<0.001) and lymph node status (P=0.021). The presence of p53-Abs was associated with lack of estrogen (ER) receptor expression (P=0.035) but was not related to progesterone receptor (PR) (P=0.567). In addition, there was a statistically significant correlation between p53-Abs and proliferation associated antigen Ki-67 (P=0.006), but no relation between c-erbB2 oncoprotein and p53-Abs was observed (P=0.112). Additionally, no correlation was noted between the presence of p53-Abs and serum carcinoembryonic antigen (CEA) or carbohydrate antigen (CA15-3). Our findings indicate that p53-Abs appears to be a promising new parameter to evaluate the cellular biology and prognosis of breast cancer.

Purification of Her-2 extracellular domain and identification of its cleavage site

The EGF family of receptors belongs to the tyrosine kinase receptor (TKR) family and plays an important role during embryonic and postnatal development and also in the progression of tumors. Her-2/neu/c-erbB-2, a member of the epidermal growth factor receptor family, can be cleaved into a soluble extra cellular domain (ECD) and a membrane-bound stub fragment. Her-2 ECD from a breast cancer cell line SKBR3 was immunopurified and analyzed with matrix-assisted laser desorption ionization (MALDI) and carboxyl terminal amino acid sequencing. A sequence within the juxtamembrane region (only 11 amino acid residues) PAEQR ASP was identified most likely as a primary site of cleavage, PA EQRASP as a minor site, that generate the ECD. The sites of cleavage are within the signature motif P/GX(5-7)P/G highly conserved in the EGF receptor family.

Selective detection of membrane proteins without antibodies: a mass spectrometric version of the Western blot

A method has been developed, called the mass western experiment in analogy to the Western blot, to detect the presence of specific proteins in complex mixtures without the need for antibodies. Proteins are identified with high sensitivity and selectivity, and their abundances are compared between samples. Membrane protein extracts were labeled with custom isotope-coded affinity tag reagents and digested, and the labeled peptides were analyzed by liquid chromatography-tandem mass spectrometry. Ions corresponding to anticipated tryptic peptides from the proteins of interest were continuously subjected to collision-induced dissociation in an ion trap mass spectrometer; heavy and light isotope-coded affinity tag-labeled peptides were simultaneously trapped and fragmented accomplishing identification and quantitation in a single mass spectrum. This application of ion trap selective reaction monitoring maximizes sensitivity, enabling analysis of peptides that would otherwise go undetected. The cell surface proteins prostate stem cell antigen (PSCA) and ErbB2 were detected in prostate and breast tumor cell lines in which they are expressed in known abundances spanning orders of magnitude.

Src family kinases and HER2 interactions in human breast cancer cell growth and survival

Evidence from murine fibroblast models and human breast cancer cells indicates that c-Src and human EGF receptor (HER1) synergize to enhance neoplastic growth of mammary epithelial cells. To investigate whether interactions between c-Src and other HER family members may also play a role in breast tumor progression, we characterized 13 human breast carcinoma cell lines and 13 tumor samples for expression of HER family members and c-Src and examined a subset of the cell lines for Src-dependent, heregulin (HRG)-augmented, anchorage-dependent and independent growth. By immunoblotting, we found that all cell lines overexpressed one or more HER family member, and 60% overexpressed c-Src. Seventy-five per cent of the tumor tissues overexpressed HER2, while 64% overexpressed c-Src. Colony formation in soft agar was enhanced by HRG in three of five cell lines tested, a response that correlated with the presence of a c-Src/HER2 heterocomplex. This result suggests that HRG may act through both HER2 and c-Src to facilitate anchorage-independent growth. In contrast, HRG had little effect on anchorage-dependent growth in any of the cell lines tested. PP1, a Src family kinase inhibitor, reduced or ablated HRG-dependent and independent soft agar growth or anchorage dependent growth, and triggered apoptosis in all cell lines tested. The apoptotic effect of PP1 could be partially or completely reversed by HRG, depending on the cell line. These results suggest that while Src family kinases may cooperate with HRG to promote the survival and growth of human breast tumor cells, they also function independently of HER2/HRG in these processes.

Changes in ErbB2 (her-2/neu), ErbB3, and ErbB4 during growth, differentiation, and apoptosis of normal rat mammary epithelial cells

Studies were undertaken to examine the natural role of ErbB2, ErbB3, and ErbB4 during the development of normal rat mammary epithelial cells (MECs) in vivo and in vitro. Immunohistochemical analysis demonstrated that mammary gland terminal end buds expressed abundant ErbB2 and ErbB4 but limited ErbB3 in pubescent rats, whereas luminal epithelial cells in nulliparous rats expressed ErbB2, ErbB3, and/or ErbB4. During pregnancy, ductal epithelial cells and stromal cells expressed abundant ErbB3 but limited ErbB2. Although ErbB2 and ErbB3 were downregulated throughout lactation, both receptors were re-expressed during involution. In contrast, ErbB4 was downregulated throughout pregnancy, lactation, and involution. Immunoblotting and immunoprecipitation studies confirmed the developmental expression of ErbB2 and ErbB3 in the mammary gland and the co-localization of distinct ErbB receptors in the mammary gland of nulliparous rats. In agreement with our in vivo findings, primary culture studies demonstrated that ErbB2 and ErbB3 were expressed in functionally immature, terminally differentiated and apoptotic MECs, and downregulated in functionally differentiated MECs. ErbB receptor signaling was required for epithelial cell growth, functional differentiation, and morphogenesis of immature MECs, and the survival of terminally differentiated MECs. Finally, ErbB4 expression did not interfere with functional differentiation and apoptosis of normal MECs.

Identification of new HER2/neu-derived peptide epitopes that can elicit specific CTL against autologous and allogeneic carcinomas and melanomas

Twenty-two new HLA-A2.1-binding peptides derived from the protooncogene HER2/neu were identified and analyzed for their capacity to elicit peptide and tumor-specific CTL responses. We used peptide-pulsed autologous DC from the ascites of patients with ovarian carcinomas to induce CTL. Of the 22 tested new HER2/neu-derived epitopes that could bind HLA-A2 with high (IC50 < 50 nM) or intermediate (50 nM < IC50 < 500 nM) affinity, we report the recognition by CTL of at least four novel epitopes, including HER2(9435), HER2(9665), HER2(9689), and HER2(10952), and confirm that of the known HER2 (9369) epitope. These epitopes were able to elicit CTL that specifically killed peptide-sensitized target cells and, most importantly, a HER2/neu-transfected cell line and the autologous tumor cells. We also confirm that HER2/neu is overexpressed in several melanoma lines, and as a new finding, report that some of these lines are sensitive to CTL induced by the HER2 (9369), HER2(9435), and HER2(9689) epitopes. Finally, CTL clones specific for HER2 (9369), HER2(9435), and HER2(9689) epitopes were isolated from tumor-specific CTL lines, further demonstrating the immunodominance of these epitopes. These findings broaden the potential application of HER2/neu-based immunotherapy.

Immune responses to all ErbB family receptors detectable in serum of cancer patients

Employing NIH3T3 transfectants with individual human ErbB receptor coding sequences as recombinant antigen sources, we detected by immunoblot analysis specific immunoreactivity against all four ErbB receptors among 13 of 41 sera obtained from patients with different types of epithelial malignancies. Overall, serum positivity was most frequently directed against ErbB2 followed by EGFR, ErbB3 and ErbB4. Specificity patterns comprised tumor patients with unique serum reactivity against ErbB2 or ErbB4. Moreover, approximately half of the positive sera exhibited concomitant reactivity with multiple ErbB receptors including EGFR and ErbB2, EGFR and ErbB4, ErbB2 and ErbB3 or EGFR, ErbB2 and ErbB3. Serum reactivity was confirmed for the respective ErbB receptors expressed by human tumor cells and corroborated on receptor-specific immunoprecipitates. Positive sera contained ErbB-specific antibodies of the IgG isotype. Representative immunohistochemical analysis of tumor tissues suggested overexpression of ErbB receptors for which serum antibodies were detectable in five of six patients. These findings implicate multiple ErbB receptors including ErbB3 and ErbB4 in addition to EGFR and ErbB2 in primary human cancer. Heterogeneity of natural ErbB-specific responses in cancer patients warrants their evaluation in light of immunotherapeutic approaches targeting these receptors.

Isolation of the intact molecule and ectodomain of C-erbB-2 oncoprotein from SK-BR-3 cells and development of immunoassays on microplate

We isolated both the intact molecule (p185) and the ectodomain (p120) of c-erbB-2 oncoprotein from SK-BR-3 breast tumor cells. The p120 was extracted from the cells by 0.05 M phosphate buffer, pH 7.2, whereas the extraction of the p185 required the presence of a detergent, such as 1% Triton X-100 in 0.05 M Tris buffer. Protease inhibitors were also included in the extraction buffer during the isolation of p185 in order to prevent cleavage of p185 to p120 by an unknown protease apparently also present in the extract. In case there was any p120 in the p185 preparation, the p120 could be separated from p185 by chromatography on a Superose 12 column. Using the p120 and p185 as calibrators, we have established two microplate sandwich immunoassays: one measures both p185 and p120 (total assay) and the other is specific for the p185. Since capturing and detecting antibodies used in the total assay react against the extracellular domain of the c-erbB-2 oncoprotein, they can therefore be used to measure the p120 in serum and p185 in breast tumor tissue cytosol. On the other hand, the p185 specific assay uses the capturing antibody against the cytosolic domain of the oncoprotein and consequently can only measure p185 in breast tumor tissue cytosol.

ErbB-1 and ErbB-2 acquire distinct signaling properties dependent upon their dimerization partner

The different epidermal growth factor (EGF)-related peptides elicit a diverse array of biological responses as the result of their ability to activate distinct subsets of ErbB receptor dimers, leading to the recruitment of different intracellular signaling networks. To specifically examine dimerization-dependent modulation of receptor signaling, we constructed NIH 3T3 cell lines expressing ErbB-1 and ErbB-2 singly and in pairwise combinations with each other ErbB family member. This model system allowed the comparison of EGF-activated ErbB-1 with ErbB-1 activated by Neu differentiation factor (NDF)-induced heterodimerization with ErbB-4. In both cases, ErbB-1 coupled to the adaptor protein Shc, but only when activated by EGF was it able to interact with Grb2. Compared to the rapid internalization of EGF-activated ErbB-1, NDF-activated ErbB-1 showed delayed internalization characteristics. Furthermore, the p85 subunit of phosphatidylinositol kinase (PI3-K) associated with EGF-activated ErbB-1 in a biphasic manner, whereas association with ErbB-1 transactivated by ErbB-4 was monophasic. The signaling properties of ErbB-2 following heterodimerization with the other ErbB receptors or homodimerization induced by point mutation or monoclonal antibody treatment were also analyzed. ErbB-2 binding to peptides containing the Src homology 2 domain of Grb2 or p85 and the phosphotyrosine binding domain of Shc varied according to the mode of receptor activation. Finally, tryptic phosphopeptide mapping of both ErbB-1 and ErbB-2 revealed that receptor phosphorylation is dependent on the dimerization partner. Differential receptor phosphorylation may, therefore, be the basis for the differences in the signaling properties observed.

Coexpression of the HER-2 gene product, p185HER-2, and epidermal growth factor receptor, p170EGF-R, on epithelial ovarian cancers and normal tissues

Monoclonal antibodies (MAbs) and immunoconjugates reactive with different antigens expressed by neoplastic cells can inhibit tumor growth. Use of these agents in combination with one another or with chemotherapy can exert additive or synergistic cytotoxicity against tumor cells. An augmented therapeutic activity with favorable therapeutic index might be attained when coexpression is observed on tumor cells, but not in normal tissues. In this study frozen sections of 19 ovarian cancers (2 stage I, 10 stage III, 2 stage IV, and 5 recurrent), as well as 29 normal tissues, were evaluated by immunohistochemistry using 11 distinct MAbs against HER-2/p185 and 2 antibodies against EGF-R/p170 to assess coexpression of these receptors. HER-2/p185 expression was detected in 5 to 100% of ovarian cancers and 0 to 50% of normal ovarian epithelia, depending on the antibody used. EGF-R/p170 expression was detected in approximately 70% of cancers and 40% of normal ovaries by both antibodies. Coexpression of p185 and p170 was observed in 47-68% of ovarian cancers and 9-18% of normal ovarian epithelial specimens depending upon the combination of antibodies used. Staining of 273 specimens from 29 normal tissues indicated that coexpression of HER-2 and EGF-R is rare. Normal tissues that coexpressed both receptors in > or =50% of the cases included cervix, endometrium, esophagus, skin, and prostate. These data confirm that HER-2 and EGF-R are more frequently expressed in advanced ovarian cancers than in normal ovarian epithelium and a significant fraction of these tumors coexpress both HER-2 and EGF-R.

Protein profiles and identification of high performance liquid chromatography isolated proteins of cancer cell lines using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) has been used to rapidly profile the protein content of human cell lysates from MCF-10 cell and variant lines. The method was used to study the protein profiles of these cells as they progressed from normal breast epithelium to fully malignant cells. Distinct differences in the protein profiles were observed with progression, and specific proteins associated with carcinogenesis (p53, c-myc, and c-erbB-2) were heavily expressed in these cells as detected by MALDI-TOFMS. These proteins were also isolated using non-porous reversed-phase high performance liquid chromatography (NP-RP-HPLC) and mass analyzed by MALDI-TOFMS to provide molecular weight information without interference from other proteins in the whole cell lysates, and to avoid suppression effects in mixtures of proteins detected by MALDI-TOFMS. In order to confirm the identity of these oncoproteins, the cell lysates were subjected to one-dimensional (1-D) gel separation and subsequently electroblotted onto a poly(vinylidene difluoride) (PVDF) membrane for further analysis. Trypsin and cyanogen bromide digestions were performed on these proteins eluted from excised PVDF bands which were then analyzed by MALDI-TOFMS. The identity of these proteins was confirmed by database matching procedures.

Immunohistochemically detected p53 and HER-2/neu expression and nuclear DNA content in familial epithelial ovarian carcinomas

BACKGROUND

Some epithelial ovarian carcinomas tend to occur more frequently in certain families. This clustering may be due to a genetic predisposition, but the role of inherited susceptibility in all families with multiple cases of ovarian carcinoma is currently unresolved. Studies characterizing familial ovarian carcinomas are few.

METHODS

From a population-based study of 559 patients with epithelial ovarian carcinoma, 27 families with 2 or more ovarian carcinoma cases occurring in first-degree relatives were identified. Histopathology, ploidy, and immunohistochemically detected p53 and HER-2/neu expression in these tumors were examined.

RESULTS

The mean age of the patients with familial ovarian carcinoma was 56.7 years. Approximately 67% of the tumors were either serous or undifferentiated adenocarcinomas. The percentage of aneuploid tumors was 46%, that of p53 positive tumors was 51%, and that of HER-2/neu positive tumors was 69%. When the families were divided into families with cases of breast carcinoma in addition to ovarian carcinoma cases and/or ovarian carcinoma in 2 consecutive generations (12 families) and families with ovarian carcinoma occurring in sisters only without cases of breast carcinoma (15 families), no differences were noted in the frequency of any of the studied variables.

CONCLUSIONS

Familial ovarian carcinomas do not appear to differ from sporadic ovarian carcinomas with regard to patient age at presentation, histopathology, ploidy, and immunohistochemically detected p53 expression. Immunohistochemically detected HER-2/neu expression was found to occur more frequently in familial ovarian carcinomas than has been reported in sporadic ovarian carcinomas.

Cell death in the Schwann cell lineage and its regulation by neuregulin

The development of Schwann cells, the myelin-forming glial cells of the vertebrate peripheral nervous system, involves a neonatal phase of proliferation in which cells migrate along and segregate newly formed axons. Withdrawal from the cell cycle, around postnatal days 2-4 in rodents, initiates terminal differentiation to the myelinating state. During this time, Schwann cell number is subject to stringent regulation such that within the first postnatal week, axons and myelinating Schwann cells attain the one-to-one relationship characteristic of the mature nerve. The mechanisms that underly this developmental control remain largely undefined. In this report, we examine the role of apoptosis in the determination of postnatal Schwann cell number. We find that Schwann cells isolated from postnatal day 3 rat sciatic nerve undergo apoptosis in vitro upon serum withdrawal and that Schwann cell death can be prevented by beta forms of neuregulin (NRG-beta) but not by fibroblast growth factor 2 or platelet-derived growth factors AA and BB. This NRG-beta-mediated Schwann cell survival is apparently transduced through an ErbB2/ErbB3 receptor heterodimer. We also provide evidence that postnatal Schwann cells undergo developmentally regulated apoptosis in vivo. Together with other recent findings, these results suggest that Schwann cell apoptosis may play an important role in peripheral nerve development and that Schwann cell survival may be regulated by access to axonally derived NRG.

All ErbB receptors other than the epidermal growth factor receptor are endocytosis impaired

Four transmembrane tyrosine kinases constitute the ErbB receptor family: the epidermal growth factor (EGF) receptor, ErbB-2, ErbB-3, and ErbB-4. We have measured the endocytic capacities of all four members of the EGF receptor family, including ErbB-3 and ErbB-4, which have not been described previously. EGF-responsive chimeric receptors containing the EGF receptor extracellular domain and different ErbB cytoplasmic domains (EGFR/ErbB) have been employed. The capacity of these growth factor-receptor complexes to mediate 125I-EGF internalization, receptor down-regulation, receptor degradation, and receptor co-immunoprecipitation with AP-2 was assayed. In contrast to the EGF receptor, all EGFR/ErbB receptors show impaired ligand-induced rapid internalization, down-regulation, degradation, and AP-2 association. Also, we have analyzed the heregulin-responsive wild-type ErbB-4 receptor, which does not mediate the rapid internalization of 125I-heregulin, demonstrates no heregulin-regulated receptor degradation, and fails to form association complexes with AP-2. Despite the substantial differences in ligand-induced receptor trafficking between the EGF and ErbB-4 receptors, EGF and heregulin have equivalent capacities to stimulate DNA synthesis in quiescent cells. These results show that the ligand-dependent down-regulation mechanism of the EGF receptor, surprisingly, is not a property of any other known ErbB receptor family member. Since endocytosis is thought to be an attenuation mechanism for growth factor-receptor complexes, these data imply that substantial differences in attenuation mechanisms exist within one family of structurally related receptors.

p185erbB2 binds to GRP94 in vivo. Dissociation of the p185erbB2/GRP94 heterocomplex by benzoquinone ansamycins precedes depletion of p185erbB2

Treatment of SKBr3 cells with benzoquinone ansamycins, such as geldanamycin (GA), depletes p185erbB2, the receptor tyrosine kinase encoded by the erbB2 gene. In the same cells, a biologically active benzoquinone photoaffinity label specifically binds a protein of about 100 kDa, and the ability of various GA derivatives to reduce the intracellular level of p185erbB2 correlates with their ability to compete with the photoaffinity label for binding to this protein. In this report, we present evidence that the approximately 100-kDa ansamycin-binding protein is GRP94. Membrane-associated p185erbB2 exists in a stable complex with GRP94. GA binding to GRP94 disrupts this complex, leading to degradation of pre-existing p185erbB2 protein, and resulting in an altered subcellular distribution of newly synthesized p185erbB2.

ErbB-2 expression is correlated with poor prognosis for patients with osteosarcoma

BACKGROUND

It has been reported that the c-erbB-2 protooncogene is frequently amplified and overexpressed in many types of cancers, except sarcomas and hematological malignancies.

METHODS

Expression of ErbB-2 in the tumors of 26 patients with conventional osteosarcoma was evaluated by immunoblotting. DNA from osteosarcoma tissues that expressed ErbB-2 were analyzed by Southern blot hybridization to examine gross rearrangement of the gene. The DNA was also surveyed for the presence of genetic mutation in the transmembrane domain of ErbB-2 by polymerase chain reaction-single-stranded DNA conformation polymorphism analysis. In addition, possible correlation of ErbB-2 expression with gender, age, histopathologic subtype, and response to chemotherapy was analyzed. Survival analysis was performed by the Kaplan-Meier test using the approximate chi-square statistic for the log-rank test.

RESULTS

The ErbB-2 protein was detected in 11 of 26 osteosarcoma tissues (42%) by immunoblot analysis. Expression of ErbB-2 was confirmed by immunohistochemical studies using specific anti-ErbB-2 monoclonal antibody. However, neither amplification of the c-erbB-2 gene nor evidence of significant genetic mutation was found in these osteosarcomas. Expression of ErbB-2 examined by immunoblotting was most strongly correlated with early pulmonary metastases (P < 0.05). Among the entire group of 26 patients in this study, Kaplan-Meier life table survival of the patients with apparent ErbB-2 expression was significantly worse than that of the patients with little ErbB-2 expression (P < 0.01).

CONCLUSIONS

In 42% of the osteosarcomas, the tumor cells expressed ErbB-2. Expression of ErbB-2 was strongly correlated with early pulmonary metastasis and poor survival rate for the patient. These data suggest that ErbB-2 plays a significant role in aggressive tumor growth and in the promotion of metastatic potential in osteosarcomas. ErbB-2 in the osteosarcoma tissues would be a useful prognostic marker for patients.

Binding of Neu differentiation factor with the extracellular domain of Her2 and Her3

The interaction of neu differentiation factor (NDF) with the extracellular domains of Her2 (sHer2) and Her3 (sHer3) have been studied using native gels, light scattering, and sedimentation equilibrium. The full-length NDF beta 2 was shown to bind sHer3 with a dissociation constant of 26 +/- 9 nM, while it showed a 1000-fold weaker binding to sHer2. Taken together, these results demonstrate that NDF is a high affinity ligand for Her3, but not for Her2. No increase in affinity of the NDF beta 2 for sHer3 was observed upon addition of sHer2 to the NDF beta 2-sHer3 mixture. Binding of NDF beta 2 to sHer3 did not induce receptor dimerization or oligomerization, the stoichiometry being one sHer3 per one NDF molecule. This finding suggests that transmembrane and/or intracellular domains of receptor family members or perhaps additional unidentified components may be involved in NDF induced dimerization and autophosphorylation, or alternatively, that dimerization is not the mechanism for Her3 autophosphorylation and signal transduction.

c-erbB-2 gene product directly associates with beta-catenin and plakoglobin

Association of the c-erbB-2 oncogene product with the cadherin-catenin complex has been demonstrated in human cancer cell lines. Although beta-catenin and plakoglobin have been proven to be crucial for the association, no previous study has shown whether the interactions are direct or indirect. In the present study, the c-erbB-2 gene product was shown by far-Western blotting analysis to associate directly with both beta-catenin and plakoglobin through its cytoplasmic domain core region, which showed extensive homology with epidermal growth factor receptor. These data suggest that c-erbB-2-induced signaling is also directly liked to the cadherin-mediated cell adhesion and "invasion-suppressor" system through beta-catenin and plakoglobin in cancers.

Identification and characterization of c-erbB-2 proteins in serum, breast tumor tissue, and SK-BR-3 cell line

We have identified and characterized c-erbB-2 protein molecules in sera from patients with carcinomas, in both cytosol and cell membrane extract from breast tumor tissue and in both the culture medium and cell extract of the SK-BR-3 cell line. These proteins were characterized by various chromatographic techniques and identified by the use of two immunoassays; one measures both the c-erbB-2 oncoprotein (p185) and its ectodomain (p120), and the other in-house assay reacts specifically for p185. We found that the majority of the immunoreactivity detected in the serum, tumor tissue cytosol, and conditioned cell medium was derived from the ectodomain molecule (p120) of the c-erbB-2 oncoprotein (p185), whereas only p185 was detected in the extracts from cell membrane of both tumor tissue and the SK-BR-3 cell line. The ectodomain molecules (p120) found in the serum, cytosol, and cell medium were very similar in terms of molecular size and charge property. The molecular weight was determined to be 120 kDa by the size exclusion HPLC method. Both p120 and p185 are glycoproteins and were retained by the ConA Sepharose column. Both molecules are also heterogeneous in charge and multiple peaks could be identified in the elution profiles of anion exchange HPLC and chromatofocusing. This information should not only facilitate the isolation of these molecules, but also improve preparation of specific antibodies, preparation of calibrators, and development of improved assays for these proteins.