Immunobiology of HER-2/<Emphasis Type="Italic">neu</Emphasis> oncoprotein and its potential application in cancer immunotherapy

HER-2/neu (also known as HER2 or c-erb-B2) is a 185-kDa protein receptor with tyrosine kinase activity and extensive homology to the epidermal growth factor (EGF) receptor. HER-2/neu is expressed in many epithelial tumors and known to be overexpressed in approximately 20–25% of all ovarian and breast cancers, 35–45% of all pancreatic adenocarcinomas, and up to 90% of colorectal carcinomas. HER-2/neu overexpression represents a marker of poor prognosis. HER-2/neu-positive tumor cells are potentially good targets for tumor-reactive cytotoxic T lymphocytes which have been utilized in immunotherapeutic trials. In addition, the humanized monoclonal antibody Herceptin has been tested in several clinical trials and proved to be an effective adjuvant therapy for HER-2/neu-positive breast and ovarian cancers. Vaccinations aiming at generating T-cell responses are being examined in both experimental and clinical trials. Natural immunity at the level of T and B cells has been observed in patients with HER-2/neu-positive tumors confirming the immunogenicity of HER-2/neu and encouraging vaccination trials with HER-2 protein–derived subunits or synthetic peptides. This review summarizes recent data from patients with various types of HER-2/neu–overexpressing cancers carrying different HLA alleles and exhibiting preexistent immunity to HER-2/neu–derived synthetic peptides. It also discusses potential advantages of the various vaccination approaches to immunotherapy targeting the HER-2/neu molecule.Keywords ImmunobiologyHER-2/neu OncoproteinCancer ImmunologyThis work was presented at the first Cancer Immunology and Immunotherapy Summer School, 8–13 September 2003, Ionian Village, Bartholomeio, Peloponnese, Greece.     

Cloning and characterization of SK2 channel from chicken short hair cells

In the inner ear of birds, as in mammals, reptiles and amphibians, acetylcholine released from efferent neurons inhibits hair cells via activation of an apamin-sensitive, calcium-dependent potassium current. The particular potassium channel involved in avian hair cell inhibition is unknown. In this study, we cloned a small-conductance, calcium-sensitive potassium channel (gSK2) from a chicken cochlear library. Using RT-PCR, we demonstrated the presence of gSK2 mRNA in cochlear hair cells. Electrophysiological studies on transfected HEK293 cells showed that gSK2 channels have a conductance of approximately 16 pS and a half-maximal calcium activation concentration of 0.74±0.17 M. The expressed channels were blocked by apamin (IC₅₀=73.3±5.0 pM) and d-tubocurarine (IC₅₀=7.6±1.0 M), but were insensitive to charybdotoxin. These characteristics are consistent with those reported for acetylcholine-induced potassium currents of isolated chicken hair cells, suggesting that gSK2 is involved in efferent inhibition of chicken inner ear. These findings imply that the molecular mechanisms of inhibition are conserved in hair cells of all vertebrates.     

Stabilization of enzymes in nanoporous materials for biosensor applications

In this study we present the results obtained from efforts to stabilize the inherently unstable m-AChE in nanoporous materials, for the development of biosensors with increased operational stability. Based on existing theoretical models, the entrapment of proteins into relatively small rigid cages drastically increases the stability of these proteins, as this is manifested by their decreased tendency to unfold. The use of two different meso/nanomaterials for the immobilization of the m-AChE shows that there is both a decrease in the leaching of the protein from the biosensor membrane to the test solution, as well as a drastic increase in the operational stability of the resulting biosensor.     

Effects of 3-methylcholanthrene and aspirin co-administration on ALDH3A1 in HepG2 cells

The effects of two different protocols of 3-methylcholanthrene (3MC) and aspirin co-administration were studied in a well-established human hepatoma cell line (HepG2). During this work, we have performed toxicity tests for cell viability/cell proliferation as well as studies on the expression of ALDH3A1 after exposure of HepG2 cells to 3MC or/and aspirin. For the evaluation of toxic concentrations of 3MC and aspirin, the WST-1 test was used. WST-1 is a reliable cytotoxicity test which is based on the cleavage of the tetrazolium salt WST-1 to formazan by mitochondrial enzymes of living cells. A broad range of drug concentrations for either 3MC (0.25-50.0 microM) or aspirin (0.05-10.0 mM) were used for cell exposure, in several periods of time. The expression of ALDH3A1 in HepG2 cells showed typical time- and dose-response curves of induction after application of 3MC (1-5 days, 1.5-5.0 microM, respectively). When cells were firstly exposed to 3MC (2.5 and 5.0 microM) and then to aspirin (0.25 mM), the induced ALDH3A1 activity was further enhanced in a statistically significant way (P<0.05). On the contrary, when aspirin application was preceded 3MC exposuring a statistically significant decrease in ALDH3A1 inducibility was observed, as compared with the application of 3MC alone.     

Evidence-based de-implementation for contradicted, unproven, and aspiring healthcare practices

Abandoning ineffective medical practices and mitigating the risks of untested practices are important for improving patient health and containing healthcare costs. Historically, this process has relied on the evidence base, societal values, cultural tensions, and political sway, but not necessarily in that order. We propose a conceptual framework to guide and prioritize this process, shifting emphasis toward the principles of evidence-based medicine, acknowledging that evidence may still be misinterpreted or distorted by recalcitrant proponents of entrenched practices and other biases.     

Novel carbon materials in biosensor systems

In this work, novel carbon materials are evaluated as transducers, stabilizers and mediators for the construction of amperometric biosensors. It is shown that materials such as fullerenes and carbon nanotubes are promising materials as electrochemical mediators and enzyme stabilizers. Additionally porous carbon and porous glassy carbon are excellent transducers for amperometric measurements, while they provide cavities adequate for enzyme immobilization. At the same time, the sensitivity to peroxide is shown to depend on the activation procedures. Treatment that introduces oxygen groups increases the sensitivity of the carbon-based sensor to hydrogen peroxide considerably. These materials are used for the construction, mediation and stabilization of glucose biosensor.     

Development and homeostasis of the skin epidermis

The skin epidermis is a stratified epithelium that forms a barrier that protects animals from dehydration, mechanical stress, and infections. The epidermis encompasses different appendages, such as the hair follicle (HF), the sebaceous gland (SG), the sweat gland, and the touch dome, that are essential for thermoregulation, sensing the environment, and influencing social behavior. The epidermis undergoes a constant turnover and distinct stem cells (SCs) are responsible for the homeostasis of the different epidermal compartments. Deregulation of the signaling pathways controlling the balance between renewal and differentiation often leads to cancer formation.