betadex and 4-4-difluoro-4-bora-3a-4a-diaza-s-indacene

Targeted delivery of photosensitizers using hydrophilic and tumor-directing carriers and site-specific activation of their photocytotoxicity are two common strategies to enhance the specificity of anticancer photodynamic therapy. We report herein a novel supramolecular bio-orthogonal approach to integrate these two functions. A β-cyclodextrin-substituted aza-boron-dipyrromethene-based photosensitizer was first complexed with a ferrocene-substituted black-hole quencher to inhibit its photosensitizing ability. Upon encountering the adamantane moieties that had been delivered to target cancer cells through specific binding of the conjugated peptide to the overexpressed epidermal growth factor receptor, the ferrocene-based guest species were displaced due to the stronger binding interactions between β-cyclodextrin and adamantane, thereby restoring the photodynamic activity of the photosensitizer. Hence, this two-step process enabled targeted delivery and site-specific activation of the photosensitizer, as demonstrated through a series of experiments in aqueous media, in a range of cancer cell lines and in tumor-bearing nude mice.

Topics: Animals; Antineoplastic Agents; Aza Compounds; beta-Cyclodextrins; Boron Compounds; Cell Line, Tumor; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Female; Humans; Hydrophobic and Hydrophilic Interactions; Macromolecular Substances; Mice; Mice, Inbred BALB C; Mice, Nude; Molecular Structure; Neoplasms, Experimental; Photochemotherapy; Photosensitizing Agents; Structure-Activity Relationship

The drug 2-hydroxypropyl-β-cyclodextrin (HPβCD) reduces lysosomal cholesterol accumulation in Niemann-Pick disease, type C (NPC) and has been advanced to human clinical trials. However, its mechanism of action for reducing cholesterol accumulation in NPC cells is uncertain and its molecular target is unknown. We found that methyl-β-cyclodextrin (MβCD), a potent analog of HPβCD, restored impaired macroautophagy/autophagy flux in Niemann-Pick disease, type C1 (NPC1) cells. This effect was mediated by a direct activation of AMP-activated protein kinase (AMPK), an upstream kinase in the autophagy pathway, through MβCD binding to its β-subunits. Knockdown of PRKAB1 or PRKAB2 (encoding the AMPK β1 or β2 subunit) expression and an AMPK inhibitor abolished MβCD-mediated reduction of cholesterol storage in NPC1 cells. The results demonstrate that AMPK is the molecular target of MβCD and its activation enhances autophagy flux, thereby mitigating cholesterol accumulation in NPC1 cells. The results identify AMPK as an attractive target for drug development to treat NPC.

Topics: AMP-Activated Protein Kinases; Autophagosomes; Autophagy; beta-Cyclodextrins; Boron Compounds; Cholesterol; Endocytosis; Enzyme Activation; Enzyme Activators; Humans; Kinetics; Models, Biological; Niemann-Pick Disease, Type C; Protein Kinase Inhibitors

The targeted delivery of a photosensitizer (PS) into specific cancer cells is an effective way to enhance the efficacy and minimize the side effects of photodynamic therapy. Herein, heptamannosylated β-cyclodextrin (β-CD) was used to mediate the formation of an adamantane (Ad)-functionalized BODIPY PS nanoparticle via strong β-CD/Ad complexation. The mannose-functionalized PS nanoparticles are selectively internalized by mannose-receptor-rich MDA-MB-231 breast cancer cells via receptor-mediated endocytosis, facilitating singlet oxygen generation to trigger apoptosis in cancer cells upon red-light irradiation. These nanoparticles exhibit excellent targeted delivery of the PS, leading to cancer cell death after irradiation both in vitro and in vivo.

Topics: Adamantane; beta-Cyclodextrins; Boron Compounds; Breast Neoplasms; Cell Death; Humans; Nanoparticles; Photochemotherapy; Photosensitizing Agents

A bis(permethylated β-cyclodextrin)-substituted aza-BODIPY has been prepared, which forms stable 1 : 1 host-guest complexes with metal-free and zinc(II) tetrasulfonated porphyrins in water. The resulting complexes exhibit predominantly a photoinduced energy or electron transfer process depending on the porphyrin-based guest.

Topics: Aza Compounds; beta-Cyclodextrins; Boron Compounds; Fluorescence; Fluorescent Dyes; Porphyrins; Spectrometry, Fluorescence; Sulfones; Water

The lipopeptide surfactin exhibits promising antimicrobial activities which are hampered by haemolytic toxicity. Rational design of new surfactin molecules, based on a better understanding of membrane:surfactin interaction, is thus crucial. We here performed bioimaging of lateral membrane lipid heterogeneity in adherent living human red blood cells (RBCs), as a new relevant bioassay, and explored its potential to better understand membrane:surfactin interactions. RBCs show (sub)micrometric membrane domains upon insertion of BODIPY analogs of glucosylceramide (GlcCer), sphingomyelin (SM) and phosphatidylcholine (PC). These domains exhibit increasing sensitivity to cholesterol depletion by methyl-β-cyclodextrin. At concentrations well below critical micellar concentration, natural cyclic surfactin increased the formation of PC and SM, but not GlcCer, domains, suggesting preferential interaction with lipid assemblies with the highest vulnerability to methyl-β-cyclodextrin. Surfactin not only reversed disappearance of SM domains upon cholesterol depletion but further increased PC domain abundance over control RBCs, indicating that surfactin can substitute cholesterol to promote micrometric domains. Surfactin sensitized excimer formation from PC and SM domains, suggesting increased lipid recruitment and/or diffusion within domains. Comparison of surfactin congeners differing by geometry, charge and acyl chain length indicated a strong dependence on acyl chain length. Thus, bioimaging of micrometric lipid domains is a visual powerful tool, revealing that intrinsic lipid domain organization, cholesterol abundance and drug acyl chain length are key parameters for membrane:surfactin interaction. Implications for surfactin preferential location in domains or at their boundaries are discussed and may be useful for rational design of better surfactin molecules.

Topics: beta-Cyclodextrins; Biological Assay; Boron Compounds; Cell Adhesion; Cells, Cultured; Cholesterol; Erythrocytes; Glucosylceramides; Humans; Lipopeptides; Membrane Microdomains; Molecular Imaging; Peptides, Cyclic; Phosphatidylcholines; Sphingomyelins; Structure-Activity Relationship

Micrometric membrane lipid segregation is controversial. We addressed this issue in attached erythrocytes and found that fluorescent boron dipyrromethene (BODIPY) analogs of glycosphingolipids (GSLs) [glucosylceramide (BODIPY-GlcCer) and monosialotetrahexosylganglioside (GM1BODIPY)], sphingomyelin (BODIPY-SM), and phosphatidylcholine (BODIPY-PC inserted into the plasma membrane spontaneously gathered into distinct submicrometric domains. GM1BODIPY domains colocalized with endogenous GM1 labeled by cholera toxin. All BODIPY-lipid domains disappeared upon erythrocyte stretching, indicating control by membrane tension. Minor cholesterol depletion suppressed BODIPY-SM and BODIPY-PC but preserved BODIPY-GlcCer domains. Each type of domain exchanged constituents but assumed fixed positions, suggesting self-clustering and anchorage to spectrin. Domains showed differential association with 4.1R versus ankyrin complexes upon antibody patching. BODIPY-lipid domains also responded differentially to uncoupling at 4.1R complexes [protein kinase C (PKC) activation] and ankyrin complexes (in spherocytosis, a membrane fragility disease). These data point to micrometric compartmentation of polar BODIPY-lipids modulated by membrane tension, cholesterol, and differential association to the two nonredundant membrane:spectrin anchorage complexes. Micrometric compartmentation might play a role in erythrocyte membrane deformability and fragility.

Topics: beta-Cyclodextrins; Blotting, Western; Boron Compounds; Cell Membrane; Cells, Cultured; Cholesterol; Chromatography, Thin Layer; Erythrocytes; Glycosphingolipids; Heterocyclic Compounds, 3-Ring; Humans; Membrane Lipids; Microscopy, Electron, Scanning; Phosphatidylcholines; Sphingomyelins

Several glycosphingolipids were labeled with the fluorphore Bodipy-Fl and analyzed using capillary electrophoresis with laser-induced fluorescence detection. GM1-, LacCer-, and Cer-Bodipy-Fl were prepared through acylation using the N-hydroxysuccinimide ester of Bodipy-Fl. Several other glycosphingolipids including GT1a-, GD1a-, GM2-, GM3-, GD3-, and GlcCer-Bodipy-Fl were enzymatically synthesized. Micellar electrokinetic capillary chromatography with a TRIS/CHES/SDS/α-cyclodextrin buffer produced better separation than an established borate/deoxycholate/methyl-β-cyclodextrin buffer. The nine Bodipy-Fl-labeled glycosphingolipid standards were separated in under 5 min, theoretical plate counts were between 640,000 and 740,000, and the limit of detection was approximately 3 pM or 240 ymol analyte injected onto the capillary.

Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Borates; Boron Compounds; Chromatography, Micellar Electrokinetic Capillary; Deoxycholic Acid; Electrophoresis, Capillary; Fluorescent Dyes; Glycosphingolipids; Limit of Detection; Sodium Dodecyl Sulfate; Taurine; Tromethamine