1-palmitoyl-2-oleoylphosphatidylcholine and Neoplasms

Circulating tumor cells (CTCs) are an important biomarker and their analysis can be considered a form of "liquid biopsy." The purpose of this book chapter is to describe the use of the 4-channel CMx (cells captured in maximum) microfluidic chip, containing special micropatterns coated with an antibody-conjugated supported lipid bilayer (SLB) on its surface, to capture and isolate CTCs from the blood of cancer patients. Captured CTCs are subsequently released by an air foam to an immunofluorescence (IF) staining panel that enables further analysis, including the identification of the primary cancer source of the CTCs.

Topics: Antibodies, Monoclonal; Antibody Specificity; Antigens, Neoplasm; Avidin; Epithelial Cell Adhesion Molecule; Fluorescent Antibody Technique; HCT116 Cells; Humans; Immunoconjugates; Lab-On-A-Chip Devices; Lipid Bilayers; Neoplasms; Neoplastic Cells, Circulating; Phosphatidylcholines; Polymethyl Methacrylate; Protein Binding

Here we used a lipid-soluble Zn(II)-bis-dipicolylamine derivative as a membrane component to develop liposomal carriers that have potential to be targeted to phosphatidylserine (PS) rich surfaces on cancer cells and to preferentially kill cancer cells without using anticancer drugs. This DPA derivative (abbreviated as DPA-Cy3[22,22]) contains the fluorophore cyanine 3 (Cy3) and two 22-carbon chains that can be anchored into liposomal membrane bilayers. DPA-Cy3[22,22]/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) unilamellar vesicles (∼150 nm) showed selective binding to PS-containing liposomes as demonstrated by anion exchange chromatography. This binding does not result in vesicle fusion or aggregation. Flow cytometry showed that DPA-Cy3[22,22]/POPC liposomes have preferential binding to MCF-7 breast cancer cells over MCF-12A noncancer cells due to 3-7 times more PS exposures on MCF-7. The extent of liposome binding with MCF-7 cells was increased by two times after cells were pretreated with the apoptotic inducer camptothecin, which increased PS exposure to the cell surface. Moreover, our flow cytometry data also suggest that local cell membrane perturbations may occur upon liposome binding and internalization. This implies that DPA-Cy3[22,22]/POPC liposomes alone may have a PS-dependent cytotoxic effect. This assertion was supported by the cell proliferation assay, which showed that 9.1 mol % DPA-Cy3[22,22]/POPC liposomes exert cytotoxicity on MCF-7 cells 3.5 times higher than that on MCF-12A cells. These results indicate that DPA-Cy3[22,22]-containing liposomes hold great promise as efficient nano drug carriers.

Topics: Amines; Anions; Cell Line, Tumor; Cell Membrane; Cell Proliferation; Drug Carriers; Humans; Lipid Bilayers; Liposomes; MCF-7 Cells; Membrane Fusion; Nanoparticles; Neoplasms; Phosphatidylcholines; Phosphatidylserines; Picolinic Acids; Unilamellar Liposomes; Zinc

64Cu radiolabelled nanodiscs based on the 11 α-helix MSP1E3D1 protein and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine lipids were, for the first time, followed in vivo by positron emission tomography for evaluating the biodistribution of nanodiscs. A cancer tumor bearing mouse model was used for the investigations, and it was found that the approximately 13 nm nanodiscs, due to their size, permeate deeply into cancer tissue. This makes them promising candidates for both drug delivery purposes and as advanced imaging agents. For the radiolabelling, a simple approach for 64Cu radiolabelling of proteins via a chelating agent, DOTA, was developed. The reaction was performed at sufficiently mild conditions to be compatible with labelling of the protein part of a lipid-protein particle while fully conserving the particle structure including the amphipathic protein fold.

Topics: Animals; Cell Line, Tumor; Copper Radioisotopes; Disease Models, Animal; Heterocyclic Compounds, 1-Ring; Heterografts; Humans; Mice; Nanostructures; Neoplasms; Particle Size; Phosphatidylcholines; Positron-Emission Tomography; Radiopharmaceuticals; Tissue Distribution; Tomography, X-Ray Computed

Alkylphosphocholines (APCs) belong to a class of synthetic antitumor lipids, which are new-generation anticancer agents. In contrast to traditional antitumor drugs, they do not attack the cell nucleus but, rather, the cellular membrane; however, their mechanism of action is not fully understood. This work compared the interactions of selected APCs [namely, hexadecylphosphocholine (miltefosine), octadecylphosphocholine and erucylphosphocholine] with the most important membrane lipids [cholesterol, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)] and examined their influence on a model membrane of tumor and normal cells. As a simple model of membranes, Langmuir monolayers prepared by mixing cholesterol either with a saturated phosphatidylcholine (DPPC), for a normal cell membrane, or with an unsaturated one (POPC), for a tumor cell membrane, have been applied. The APC-lipid interactions, based on experimental surface pressure (π) versus mean molecular area (A) isotherms, were analyzed qualitatively (with mean molecular area values) as well as quantitatively (with the ΔG(exc) function). Strong attractive interactions were observed for mixtures of APCs with cholesterol, contrary to the investigated phosphatidylcholines, for which the interactions were found to be weak with a tendency to separation of film components. In ternary monolayers it has been found that the investigated model systems (cholesterol/DPPC/APC vs cholesterol/POPC/APC) differ significantly as regards the interactions between film-forming molecules. The results demonstrate stronger interactions between the components of cholesterol/POPC/APC monolayers compared to cholesterol/POPC film, mimicking tumor cell membranes. In contrast, the interactions in cholesterol/DPPC/APC films were found to be weaker than those in the cholesterol/DPPC system, serving as a model of healthy cell membranes, thus proving that the incorporation of APCs is, from a thermodynamic point of view, unfavorable for binary cholesterol/DPPC monolayers. It can be concluded that the composition of healthy cell membranes is a natural barrier preventing the incorporation of APCs into normal cells.

Topics: Animals; Cell Membrane; Cholesterol; Humans; Neoplasms; Phosphatidylcholines; Phosphorylcholine; Unilamellar Liposomes

In continuation with our studies concerning the synthesis, characterization and biological evaluation of nucleolipidic Ru(III) complexes, a novel design for this family of potential anticancer agents is presented here. As a model compound, a new uridine-based nucleolipid has been prepared, named HoUrRu, following a simple and versatile synthetic procedure, and converted into a Ru(III) salt. Stable formulations of this highly functionalized Ru(III) complex have been obtained by co-aggregation with either the zwitterionic lipid POPC or the cationic DOTAP, which have been subjected to an in-depth microstructural characterization, including DLS, SANS and EPR measurements. The in vitro bioactivity profile of HoUrRu, as a pure compound or in formulation with POPC or DOTAP, reveals high antiproliferative activity against MCF-7 and WiDr human cancer cell lines.

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Survival; Coordination Complexes; Drug Design; Fatty Acids, Monounsaturated; Humans; Neoplasms; Phosphatidylcholines; Quaternary Ammonium Compounds; Ruthenium; Uridine

We find that pH-(low)-insertion-peptide (pHLIP)-facilitated translocation of phalloidin, a cell-impermeable polar toxin, inhibits the proliferation of cancer cells in a pH-dependent fashion. The monomeric pHLIP inserts its C terminus across a membrane under slightly acidic conditions (pH 6-6.5), forming a transmembrane helix. The delivery construct carries phalloidin linked to its inserting C terminus via a disulfide bond that is cleaved inside cells, releasing the toxin. To facilitate delivery of the polar agent, a lipophilic rhodamine moiety is also attached to the inserting end of pHLIP. After a 3 h incubation at pH 6.1-6.2 with 2-4 μM concentrations of the construct, proliferation in cultures of HeLa, JC, and M4A4 cancer cells is severely disrupted (> 90% inhibition of cell growth). Treated cells also show signs of cytoskeletal immobilization and multinucleation, consistent with the expected binding of phalloidin to F actin, stabilizing the filaments against depolymerization. The antiproliferative effect was not observed without the hydrophobic facilitator (rhodamine). The biologically active delivery construct inserts into 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine lipid bilayers with an apparent pK(a) of ∼6.15, similar to that of the parent pHLIP peptide. Sedimentation velocity experiments show that the delivery construct is predominantly monomeric (> 90%) in solution under the conditions employed to treat cells (pH 6.2, 4 μM). These results provide a lead for antitumor agents that would selectively destroy cells in acidic tumors. Such a targeted approach may reduce both the doses needed for cancer chemotherapy and the side effects in tissues with a normal pH.

Topics: Actins; Amanita; Cell Line, Tumor; Cell Proliferation; Humans; Hydrogen-Ion Concentration; Membrane Proteins; Molecular Structure; Mycotoxins; Neoplasms; Phalloidine; Phosphatidylcholines; Protein Transport