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Jan Marik

Publications and source records attributed to Jan Marik.

13 recordsLinked to original sources
PubMed2006

The minimum element of a synthetic peptide required to block prostate tumor cell migration.

Human prostate tumor cell invasion and metastasis are dependent in part on cell adhesion to extracellular matrix proteins and cell migration. We previously identified a synthetic D-amino acid tumor cell adhesion peptide called HYD1 (kikmviswkg) that supported adhesion of tumor cells derived from breast, prostate, ovary and pancreas tissue. Alanine substitution analysis and a peptide deletion strategy were used to determine the minimal element of HYD1 necessary for bioactivity in a prostate cancer cell line called PC3N. Bioactivity was measured by assays of cell adhesion, migration and ERK signaling. The most potent element of HYD1 necessary to support cell adhesion was kmvixw, the block to migration required xkmviswxx and activation of ERK signaling required ikmviswxx. The shortest sequence active in all three assays was iswkg. The HYD1 peptide contains overlapping elements required for adhesion, blocking migration and the activation of ERK signaling. These linear peptide sequences provide the starting point for development of novel compounds to target cancer cell adhesion and migration.

Amino Acid Sequence↗
PubMed2006

Fully automated preparation of n.c.a. 4-[18F]fluorobenzoic acid and N-succinimidyl 4-[18F]fluorobenzoate using a Siemens/CTI chemistry process control unit (CPCU).

The widely used bifunctional labeling reagent 4-[18F]fluorobenzoic acid ([18F]FBA) and its activated form N-succinimidyl 4-[18F]fluorobenzoate ([18F]SFB) were prepared using a modified Siemens/CTI chemistry process control unit (CPCU) double vessel [18F]FDG module. The products were obtained with a radiochemical yield greater than 99% with decay corrected yields of 77+/-5% (n=4) for [18F]FBA and 46+/-5% (n=4) for [18F]SFB. The presented synthetic procedure is highly reproducible and fully automated.

Benzoates↗
PubMed2006

Combinatorial chemistry identifies high-affinity peptidomimetics against alpha4beta1 integrin for in vivo tumor imaging.

Small peptide-based agents have attracted wide interest as cancer-targeting agents for diagnostic imaging and targeted therapy. There is a need to develop new high-affinity and high-specificity peptidomimetic or small-molecule ligands against cancer cell surface receptors. Here we report on the identification of a high-affinity peptidomimetic ligand (LLP2A; IC50 = 2 pM) against alpha4beta1 integrin using both diverse and highly focused one-bead-one-compound combinatorial peptidomimetic libraries in conjunction with high-stringency screening. We further demonstrate that LLP2A can be used to image alpha4beta1-expressing lymphomas with high sensitivity and specificity when conjugated to a near infrared fluorescent dye in a mouse xenograft model. Thus, LLP2A provides an important tool for noninvasive monitoring of alpha4beta1 expression and activity during tumor progression, and it shows great potential as an imaging and therapeutic agent for alpha4beta1-positive tumors.

Animals↗
PubMed2006

Peptide ligands targeting integrin alpha3beta1 in non-small cell lung cancer.

Lung cancer is one of the most common cancers and is the leading cause of cancer death. We wish to identify peptide ligands for unique cell surface receptors of non-small lung cancer with the hope of developing these ligands as diagnostic and therapeutic agents. Using the method of 'one-bead one-peptide' combinatorial chemistry, a library of random cyclic octapeptides was synthesized on polystyrene beads. This library was used to screen for peptides that promoted attachment of lung adenocarcinoma cells employing a 'cell-growth-on-bead' assay. Consensus peptide sequences of cNGXGXXc were identified. These peptides promoted cell adhesion by targeting integrin alpha3beta1 over-expressed in non-small lung cancer cells. These peptide beads can be applied to capture cancer cells in malignant pleural fluid for purpose of diagnosis of lung cancer.

Carcinoma, Non-Small-Cell Lung↗
PubMed2005

Chemical xenobiotics and mitochondrial autoantigens in primary biliary cirrhosis: identification of antibodies against a common environmental, cosmetic, and food additive, 2-octynoic acid.

Emerging evidence has suggested environmental factors as causative agents in the pathogenesis of primary biliary cirrhosis (PBC). We have hypothesized that in PBC the lipoyl domain of the immunodominant E2 component of pyruvate dehydrogenase (PDC-E2) is replaced by a chemical xenobiotic mimic, which is sufficient to break self-tolerance. To address this hypothesis, based upon our quantitative structure-activity relationship data, a total of 107 potential xenobiotic mimics were coupled to the lysine residue of the immunodominant 15 amino acid peptide of the PDC-E2 inner lipoyl domain and spotted on microarray slides. Sera from patients with PBC (n = 47), primary sclerosing cholangitis (n = 15), and healthy volunteers (n = 20) were assayed for Ig reactivity. PBC sera were subsequently absorbed with native lipoylated PDC-E2 peptide or a xenobiotically modified PDC-E2 peptide, and the remaining reactivity analyzed. Of the 107 xenobiotics, 33 had a significantly higher IgG reactivity against PBC sera compared with control sera. In addition, 9 of those 33 compounds were more reactive than the native lipoylated peptide. Following absorption, 8 of the 9 compounds demonstrated cross-reactivity with lipoic acid. One compound, 2-octynoic acid, was unique in both its quantitative structure-activity relationship analysis and reactivity. PBC patient sera demonstrated high Ig reactivity against 2-octynoic acid-PDC-E2 peptide. Not only does 2-octynoic acid have the potential to modify PDC-E2 in vivo but importantly it was/is widely used in the environment including perfumes, lipstick, and many common food flavorings.

Amino Acid Sequence↗
PubMed2005

Peptide and small-molecule microarrays.

Two methods that use chemoselective ligation chemistry to prepare peptide and small-molecule microarrays are described here. The first method involves the functionalization of a glass slide with a glyoxylyl group, followed by chemoselective ligation of small molecules or peptides to the functionalized surface via a covalent bond. In the second method, peptides or small molecules are first conjugated to a macromolecular scaffold. The final ligand-scaffold conjugates are then spotted and adsorbed onto the solid surface. Three different assay methods to screen such chemical microarrays are described.

Animals↗
PubMed2005

Identification of novel targeting peptides for human ovarian cancer cells using "one-bead one-compound" combinatorial libraries.

Using "one-bead one-compound" combinatorial chemistry technology, we generated random peptide libraries containing millions of 90 mum TentaGel beads, each with its own unique amino acid sequence. A cyclic random 8-mer library was screened with CAOV-3 (a human ovarian adenocarcinoma cell line) and beads with a unique ligand that bind to the cell surface receptors were coated by one or more layers of cells. These positive beads were isolated, stripped, and microsequenced. Several peptide motifs were identified from these screenings, some of which were novel and unique, e.g., cDGX(4)GX(6)X(7)c. Structure-activity relationship studies of this peptide revealed that the l-aspartate residue at position 2, the two glycines at positions 3 and 5, and the two d-cysteines at the amino and COOH terminus are critical for activity. In addition, a hydrophobic residue was preferred at position X(4), whereas amino acids at positions X(6) and X(7) were more variable. Binding of this peptide to a number of different cancer cell lines and normal cells was also determined and we observed that peptides with this motif bound preferentially to three other human ovarian cancer cell lines (ES-2, SKOV-3, and OVCAR-3) as well as a human glioblastoma cancer cell line (A172). Structural analysis of the peptides using high-resolution nuclear magnetic resonance spectroscopy revealed strong conformational similarity among all peptides with cX(1)GX(4)GX(6)X(7)c motif. Blocking study with a panel of anti-integrin antibodies strongly suggests alpha3 integrin present on these ovarian adenocarcinoma cells is the target receptor for this peptide.

Adenocarcinoma↗
PubMed2004

Xenobiotic-induced loss of tolerance in rabbits to the mitochondrial autoantigen of primary biliary cirrhosis is reversible.

Previous work has demonstrated that immunization of rabbits with the xenobiotic 6-bromohexanoate coupled to BSA breaks tolerance and induces autoantibodies to mitochondria in rabbits. Such immunized rabbits develop high-titer Abs to pyruvate dehydrogenase complex (PDC)-E2, the major autoantigen of primary biliary cirrhosis. In efforts to map the fine specificity of these autoantibodies, rabbits were immunized biweekly with 6-bromohexanoate-BSA and screened for reactivity using a unique xenobiotic-peptide-agarose microarray platform with an emphasis on identifying potential structures that mimic the molecular image formed by the association of lipoic acid with the immunodominant PDC-E2 peptide. Essentially, a total of 23 xenobiotics and lipoic acid were coupled to the 12-mer peptide backbones, PDC, a mutant PDC, and albumin. As expected, we succeeded in breaking tolerance using this small organic molecule coupled to BSA. However, unlike multiple experimental methods of breaking tolerance, we report in this study that, following continued immunization, the rabbits recover tolerance. With repeated immunization, the response to the rPDC-E2 protein increased with a gradual reduction in autoantibodies against the lipoic acid-peptide, i.e., the primary tolerance-breaking autoantigen. Detailed analysis of this system may provide strategies on how to restore tolerance in patients with autoimmune disease.

Animals↗
PubMed2004

Novel peptide ligands for integrin alpha 4 beta 1 overexpressed in cancer cells.

Using the "one-bead one-peptide" combinatorial technology, a library of random cyclic octapeptides and nonapeptides, consisting of natural and unnatural amino acids, was synthesized on polystyrene beads. This library was used to screen for peptides that promoted attachment and proliferation of bronchioloalveolar carcinoma cells (H1650), employing a "cell growth on bead" assay. Consensus peptide sequences of cNleDXXXXc and cXNleDXXXXc (where Nle is norleucine) were identified. With alanine scanning and site-directed deletion, a typical ligand consisted of a motif of -NleDI/V/Nle- with two flanking cysteines. These peptide ligands were specific for promoting cell attachment of the H1650 cells and the cells of lymphoid cancers (Jurkat and Raji) but not other selected human cell lines of lung cancer and fibroblast. In an antibody blocking assay, integrin alpha(4)beta(1), which was overexpressed in H1650, Jurkat, and Raji, was identified as a putative receptor for these peptide ligands. Using Chinese hamster ovary cells transfected with either wild-type or mutant integrin alpha(4), a critical binding site for these peptides was localized to the glycine residue at position 190 of integrin alpha(4).

Alanine↗
PubMed2002

A novel peptide-based encoding system for "one-bead one-compound" peptidomimetic and small molecule combinatorial libraries.

The "one-bead one-compound" (OBOC) combinatorial library method is highly efficient, especially when used with well-established on-bead binding or functional assays. Literally, millions of compounds can be screened concurrently within 1 to 2 days. However, structure determination of peptidomimetic and small molecule compounds on one single bead is not trivial. A novel, highly efficient, and robust peptide-based encoding system has been developed for OBOC peptidomimetic and small molecule combinatorial libraries. In this system, topologically segregated bifunctional beads, which are made by a simple biphasic solvent strategy, are employed for the preparation and screening of an OBOC combinatorial peptidomimetic and small molecule libraries. Testing molecules are on the outer layer, and the coding tags in the interior of the bead do not interfere with screening. The coding tag is a peptide containing a large number of unnatural alpha-amino acids derived from different building blocks used for generating the peptidomimetic or small molecule. By coupling common building blocks simultaneously to the scaffold of the testing compound and to the side chains of the alpha-amino acids on the coding peptide, extra synthetic steps are eliminated and the amount of undesirable side products is minimized. Positive bead decoding is easy and straightforward as there is no need for cleavage and retrieval of the coding tag, and positive beads can be sequenced directly with Edman degradation. To demonstrate the efficiency and simplicity of our encoding system, an encoded 158 400-member model peptidomimetic library has been generated and screened for ligands that bind to streptavidin. Potent and novel ligands with clear motifs have been identified.

Amino Acids↗
PubMedDate not supplied

Solid-phase synthesis of 2-[18F]fluoropropionyl peptides.

The 2-[(18)F]fluoropropionic (2-[(18)F]FPA) acid is used as a prosthetic group for radiolabeling proteins and peptides for targeted imaging using positron emission tomography (PET). Radiolabeling of compounds with more than one acylable functional group can lead to complex mixtures of products; however, peptides can be labeled regioselectively on the solid phase. We investigated the use of a solid-phase approach for the preparation of 2-[(18)F]fluoropropionyl peptides. [(18)F]FPA was prepared and conjugated to the peptides attached to the solid phase support. The (18)F-labeled peptides were obtained in 175 min with decay corrected yields of 10% (related to [(18)F]fluoride) and with a purity of 76-99% prior HPLC purification. The suitability of various coupling reagents and solid supports were tested for radiolabeling of several peptides of various lengths.

Amino Acid Sequence↗
PubMedDate not supplied

Near-infrared optical imaging of ovarian cancer xenografts with novel alpha 3-integrin binding peptide "OA02".

Through screening of random one-bead one-compound (OBOC) libraries, we previously identified cyclic peptides with the cDGXGXXc motif that bind to alpha3 integrin subunit on ovarian adenocarcinoma cell lines ES-2, SKOV-3, and CaOV-3. We subsequently synthesized two secondary libraries based on this motif and identified new peptides that bound with a higher affinity to these cell lines. One of the peptides identified from the 20% "down-substituted" focused library was the c-dGHCitGPQ-c ("OA02") peptide. The goal of this study was to determine whether this peptide labeled with near-infrared probes could be detected after intravenous injection in ovarian tumor-bearing mice and if it would selectively localize in the tumor. Three different forms of this peptide were synthesized, "OA02"-biotin (noncovalently linked to streptavidin-Cy5.5); "OA02"-Cy5.5 and "OA02"-AlexaFluo 680. Using a KODAK IS2000MM image station, these peptide probes were used at the near-infrared (NIR) spectra to image nude mice bearing ES-2 (alpha3 integrin positive) and Raji (alpha3 integrin negative) xenografts. The peptide probe displayed highly specific tumor uptake within 15 min, which lasted for 70 min for "OA02"-Cy5.5 and "OA02"-AlexaFluo 680 and for 24 hours for "OA02"-biotin-streptavidin-Cy5.5. Some kidney and bladder signal were noted. Prior injection with anti-alpha3 monoclonal antibody blocked the binding of this peptide to the ES-2 tumors.

Adenocarcinoma↗