Chemosensitization of Prostate Carcinoma Cells with a Receptor-directed Smac Conjugate.

Background: Second mitochondrial activator of caspase (Smac) is a short mitochondrial peptide. When released from the mitochondria into the cytoplasm, it binds to inhibitor of apoptotic proteins (IAPs) within the cytoplasm and prevents them from inhibiting apoptosis.

Objective: Delivery of external synthetic Smac peptide into the cytoplasm of malignant cells could greatly improve the efficiency of apoptosis-inducing chemotherapeutic agents.

The gastrin/cholecystokinin-B receptor on prostate cells--a novel target for bifunctional prostate cancer imaging.

The means of identifying prostate carcinoma and its metastases are limited. The contrast agents used in magnetic resonance imaging clinical diagnostics are not taken up into the tumor cells, but only accumulate in the interstitial space of the highly vasculated tumor. We examined the gastrin/cholecystokinin-B receptor as a possible target for prostate-specific detection using the C-terminal seven amino acid sequence of the gastrin peptide hormone.

Rhodamine-marked bombesin: a novel means for prostate cancer fluorescence imaging.

The gastrin releasing peptide receptor (GRPR) has been found to be strongly expressed in various types of cancers such as prostate and breast carcinomas. The GRPR ligands gastrin releasing peptide and bombesin can play a very significant role in cancer therapy and diagnostics. In this study we synthesized unlabeled bombesin BBN along with two conjugates in which the correct bombesin (BBN-Rhd) and a mutant bombesin (mBBN-Rhd) sequence was coupled to rhodamine, a fluorescent dye.

Novel bourgeonal fragrance conjugates for the detection of prostate cancer.

The methods used for detection of prostate cancer and prostate cancer lymph node metastases in medical diagnostics leave room for improvement. Currently, no means of identifying metastasized lymph nodes other than biopsies is available. Markers which are exclusively found on prostate cancer cells present a focal point for potential imaging methods.

Chemical modification allows phallotoxins and amatoxins to be used as tools in cell biology.

Phallotoxins inhibit the dynamics of microfilaments in cells and lead to apoptosis. Due to poor cellular uptake these effects cannot be studied in live cells, even at millimolar toxin concentrations, nor can phalloidin be used for the elimination of tumor cells. Uptake is greatly enhanced by conjugation of phallotoxins to either lipophilic or polycationic moieties, such as oleic acid, polylysine, or Tat-peptide.

Evaluating the diagnostic and chemotherapeutic potential of vancomycin-derived imaging conjugates.

The main use of glycopeptide antibiotics is treatment of infections which are resistant to the commonly used β- lactam antibiotics. Antitumor activity has also been reported for some glycopeptide antibiotics like bleomycin. In the present study we investigated the chemotherapeutic and diagnostic potential of two imaging agent derivatives of the glycopeptide antibiotic vancomycin.

Novel gastrin receptor-directed contrast agents - potential in brain tumor magnetic resonance imaging.

Magnetic resonance imaging (MRI) is presently the method of choice for detection of brain tumors. However, MRI alone is not conclusive. As the commonly used contrast agents do not bind to the cells and are not taken up into the cells, they generally do accumulate in regions where the blood-brain-barrier is disrupted.

Potential of the gastric motility drug lorglumide in prostate cancer imaging.

The use of tissue-specific receptor ligands is a promising approach for cancer diagnostics and therapy. Lorglumide, a highly effective competitive ligand for the cholecystokinine-A receptor (CCKRA) was conjugated to a fluorescent dye and a magnetic resonance imaging (MRI) contrast agent to obtain a bifunctional marker for tissue with high CCKRA expression. An intermediate conjugate containing only lorglumide and a fluorescent dye was also produced.

Using the neurotransmitter serotonin to target imaging agents to glioblastoma cells.

The neurotransmitter serotonin is involved in numerous bodily functions via seven different serotonin receptor subfamilies. Serotonin plays a role in gastrointestinal functions like intestinal secretion or peristalsis and neuropsychiatric events like depression or migraine. One of these subtypes has been found on glioblastoma cells, inducing growth promotion.

A novel lily-of-the-valley fragrance contrast agent for magnetic resonance and fluorescence imaging of prostate cancer cells.

Detection of prostate carcinoma metastases is currently performed either via indirect tests like the prostate specific antigen (PSA) or prostate cancer gene 3 (PCA3) or by biopsies from masses found with medical imaging methods. Our goal was to use an ectopic odorant receptor to target prostate-derived cells throughout the body for imaging by magnetic resonance and fluorescence imaging. We synthesized a conjugate containing undecylic aldehyde (an antagonist of the human olfactory receptor hOR17-4), gadolinium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (a common magnetic resonance contrast agent) and fluorescein isothiocyanate (a fluorescent dye).

Imaging of human glioma cells by means of a Syndecan-4 directed DOTA-conjugate.

The extracellular glycoprotein Tenascin-C (TN-C) is highly upregulated in gliomas. Therefore, many chemotherapies with radiolabeled antibodies against TN-C have been performed. However, TN-Cs binding partner Syndecan-4 did not play any role as a therapeutic or imaging target in gliomas.

Cell nucleus directed 2,3,5-triiodobenzoic acid conjugates.

Triiodobenzoic acid (TIBA) represents the core structure of most clinically used contrast agents for computed tomography and other X-ray procedures. To construct an intracellular radiopaque contrast agent, TIBA was coupled to various different positively and negatively charged fluorescein iothiocyanate (FITC)-labelled peptides. TIBA coupled to the SV40 T Antigen nuclear localization sequence (NLS) stained 80% of human glioma cells and caused cell death.

The lily-of-the-valley fragrance receptor--potential in prostate cancer imaging.

Background: The early diagnosis of prostate cancer and its metastases still remains a great challenge. Recently, olfactory receptors have been found in healthy and malignant prostate tissue. If conjugated to a dye, olfactory receptor ligands would represent candidates for markers of not only olfactory cells but also prostate tissue.

Novel cell nucleus directed fluorescent tetraazacyclododecane-tetra-acetic acid compounds.

Peptide conjugates derived from the SV 40 T antigen nuclear localisation sequence (NLS) have been successfully used to translocate both fluorescein isothiocyanate (FITC) and Gadolinium (Gd)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) into the cytoplasm and nucleus of glioma cells. However, uptake occurred only in up to 35% of cells. To improve cellular uptake, we designed three novel FITC-labelled Gd-DOTA conjugates.

A novel polyarginine containing Smac peptide conjugate that mediates cell death in tumor and healthy cells.

The seven N-terminal amino acids AVPIAQK (SmacN7) of the mitochondrial protein Smac (second mitochondria-derived activator of caspase) promote caspase activation by binding specifically to inhibitor of apoptosis proteins (IAPs) and blocking their inhibitory activity. SmacN7 cannot pass through the cell membrane, but to be of therapeutic use it would be essential for it to enter the cell. To achieve transmembrane transport of SmacN7 we coupled it to a novel fluorescein isothiocyanate (FITC)-labelled transmembrane transport peptide RRRRK(FITC)RRRR via ss-alanine to produce the conjugate AVPIAQKssA RRRRK(FITC)RRRR.

Cellular uptake of cationic gadolinium-DOTA peptide conjugates with and without N-terminal myristoylation.

Cellular and nuclear uptake of dual labelled conjugates could be of great value for chemotherapy and cancer diagnostics. Therefore we designed conjugates in which gadolinium (Gd)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), a contrast agent for magnetic resonance imaging and fluorescein isothiocyanate (FITC), a fluorescence marker were coupled to membrane translocation sequences (MTS). The MTSs we employed were the third helix of the Antennapedia homeodomain, the HIV-1 Tat peptide and the N-myristoylated HIV-1 Tat peptide.

Value of apoptin's 40-amino-acid C-terminal fragment for the differentiation between human tumor and non-tumor cells.

Apoptin, a protein of the chicken anemia virus (CAV), consists of 121 amino acids (aa) and represents a novel, potentially tumor-specific therapeutic and diagnostic agent. The C-terminal part of Apoptin (aa 81-121) is believed to contain a bipartite nuclear localization signal (NLS) (NLS1: aa 82-88 and NLS2: aa 111-121), which is only active in tumor cells after phosphorylation of threonine(108) by tumor-specific cytoplasmic phosphokinases. Furthermore, a nuclear export signal (NES) (aa 97-105) seems to enable nuclear export of Apoptin only in healthy cells.

The influence of 2,4,6-tribromophenyl isocyanate on the cellular and nuclear uptake of the SV 40 T antigen nuclear localization sequence.

The objective of the present study was to evaluate the influence of 2,4,6-tribromophenyl isocyanate (TBPI) on the cellular and nuclear uptake of the fluorescein isothiocyanate (FITC) labeled SV 40 T antigen nuclear localization sequence in human LN18 and U373 glioma cells. Therefore, the FITC-labeled nuclear localization sequence (NLS) of the SV 40 T antigen was coupled to 2,4,6-TBPI. This TBPI-NLS conjugate was taken up by the cell nuclei of more than 90% of human malignant glioma cells.

The differential influence of non-iodinated and mono- or diiodinated benzoic acids on cellular and nuclear uptake of the nuclear localization sequence of the SV 40 T antigen.

We synthesized several novel compounds to evaluate the different effects of non-iodinated and mono- or diiodinated benzoic acid on the cellular and nuclear uptake of the SV 40 T antigen nuclear localization sequence (NLS) in human LN18 and U373 glioma cells. The skeletal structure of all the conjugates contained the fluorescein isothiocyanate (FITC)-labeled NLS of the SV 40T antigen, to which either benzoic acid, mono- or diiodobenzoic acid was coupled. As shown by confocal laser scanning microscopy (CLSM) and fluorescence-activated cell sorting (FACS), the basic FITC-labeled NLS alone was taken up by the nuclei of only a few glioma cells which remained intact.

Novel dual labelled nucleus-directed conjugates containing correct and mutant nuclear localisation sequences.

Gadolinium (Gd)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) is commonly used as contrast agent in magnetic resonance imaging (MRI), but cannot enter the cytoplasm or cell nucleus. We designed a tetrapeptide carrying fluorescein isothiocyanate (FITC) and Gd-DOTA. This conjugate was coupled to the nuclear localisation sequence (NLS) of the Simian Virus (SV) 40 T antigen elongated by four arginines.

Coordination of three and four Cu(I) to the alpha- and beta-domain of vertebrate Zn-metallothionein-1, respectively, induces significant structural changes.

Vertebrate metallothioneins are found to contain Zn(II) and variable amounts of Cu(I), in vivo, and are believed to be important for d10-metal control. To date, structural information is available for the Zn(II) and Cd(II) forms, but not for the Cu(I) or mixed metal forms. Cu(I) binding to metallothionein-1 has been investigated by circular dichroism, luminescence and 1H NMR using two synthetic fragments representing the alpha- and the beta-domain.

Comparative analysis of the human and chicken prion protein copper binding regions at pH 6.5.

Recent experimental evidence supports the hypothesis that prion proteins (PrPs) are involved in the Cu(II) metabolism. Moreover, the copper binding region has been implicated in transmissible spongiform encephalopathies, which are caused by the infectious isoform of prion proteins (PrP(Sc)). In contrast to mammalian PrP, avian prion proteins have a considerably different N-terminal copper binding region and, most interestingly, are not able to undergo the conversion process into an infectious isoform.

The crystal structure of yeast copper thionein: the solution of a long-lasting enigma.

We report here the crystal structure of yeast copper thionein (Cu-MT), determined at 1.44-A resolution. The Cu-MT structure shows the largest known oligonuclear Cu(I) thiolate cluster in biology, consisting of six trigonally and two digonally coordinated Cu(I) ions.

Synthetic human prion protein octapeptide repeat binds to the proteinase K active site.

Proteinase K is widely used in tests for the presence of infectious prion protein causing fatal spongiform encephalopathies. To investigate possible interactions between the enzyme and the functionally important N-terminal prion domain, we crystallized mercury-inhibited proteinase K in the presence of the synthetic peptides GGGWGQPH and HGGGW. The octapeptide sequence is identical to that of a single octapeptide repeat (OPR) from the physiologically important OPR region.

Modulation of red cell glycolysis: interactions between vertebrate hemoglobins and cytoplasmic domains of band 3 red cell membrane proteins.

Several vital functions/physical characteristics of erythrocytes (including glycolysis, the pentose phosphate pathway, ion fluxes, and cellular deformability) display dependence on the state of hemoglobin oxygenation. The molecular mechanism proposed involves an interaction between deoxyhemoglobin and the cytoplasmic domain of the anion-exchange protein, band 3 (cdB3). Given that band 3 also binds to membrane proteins 4.