Biomaterial-Mediated Exogenous Facile Coating of Natural Killer Cells for Enhancing Anticancer Efficacy toward Hepatocellular Carcinoma

Natural killer (NK) cells exhibit a good therapeutic efficacy against various malignant cancer cells. However, the therapeutic efficacy of plain NK cells is relatively low due to inadequate selectivity for cancer cells. Therefore, to enhance the targeting selectivity and anticancer efficacy of NK cells, we have rationally designed a biomaterial-mediated ex vivo surface engineering technique for the membrane decoration of cancer recognition ligands onto NK cells. Our designed lipid conjugate biomaterial contains three major functional moieties: (1) 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) lipid for cell membrane anchoring, (2) polyethylene glycol for intracellular penetration blocker, and (3) lactobionic acid (LBA) for cancer recognition. The biomaterial was successfully applied to NK cell surfaces (LBA-NK) to enhance recognition and anticancer functionalities, especially toward asialoglycoprotein receptor (ASGPR)-overexpressing hepatocellular carcinoma. Highly efficient and homogeneous NK cell surface editing was achieved with a simple coating process while maintaining intrinsic properties of NK cells. LBA-NK cells showed potential ASGPR-mediated tumor cell binding (through LBA-ASGPR interaction) and thereby significantly augmented anticancer efficacies against HepG2 liver cancer cells. Thus, LBA-NK cells can be a novel engineering strategy for the treatment of liver cancers via facilitated immune synapse interactions in comparison with currently available cell therapies

Intramolecular Oxidative Diamination and Aminohydroxylation of Olefins under Metal-Free Conditions

A metal-free procedure that is simple to operate and convenient to handle was developed for the facile intramolecular oxidative diamination of olefins using an iodobenzene diacetate oxidant and a halide additive to furnish bisindolines at room temperature. The present reaction is featured by mild conditions, a broad substrate scope, and excellent functional group tolerance. The same protocol was successfully extended to the aminohydroxylation

Ligand-binding site interactions.

<p>Four snapshots from the MD simulations (AD) are compared with corresponding binding site conformations from the crystallographic protomers A and B (EH). Snapshots showing PhC phosphate moiety interactions with specific protein side-chains are arranged as follows: (A) Y30 and Y54 at 60 ns, (B) Y60 at 100 ns, (C) Y75 and Y100 at 150 ns, and (D) Y108 at 175 ns. Binding site residues Y30, Y54, W47, W58 (from PDC109/a), and Y75, Y100, W93, W106 (from PDC109/b) are shown in orange, residues Y60 and Y108 (from PDC109/b) are shown in purple, while bound PhC molecules are shown as charge-colored spheres. Residue labels are indicated in the crystal structure panels E and G.</p

MD and X-ray results for distances between binding sites of PDC109 and PhC.

<p>Distances are in Å and were determined by averaging through MD trajectories (protomer A) and from the crystal structure (protomers A and B, *PDB ID: 1h8p). Distances for tryptophans were calculated between the six-carbon ring centers of sidechain indoles and the PhC quaternary ammonium nitrogen. Distances for tyrosines were calculated between sidechain hydroxyl oxygens and the average position of three PhC phosphate oxygens. Average MD distances and standard deviations were calculated using the initial 230 ns trajectories because PhC started to detach from the binding pocket of PDC109/a at about 240 ns.</p

Comparison of the first three normal modes and principal components.

<p>Overlapping ribbon conformations for the three lowest normal modes are shown at t = 0 (red) and (blue) with the normalized eigenvector vibrational amplitudes scaled by a factor of 200. The normal mode index corresponds to specific vibrational frequencies as follows:  = 1 (hinge-bend), 0.80 cm;  = 2 (twist), 1.72 cm;  = 3 (tilt), 3.08 cm. Overlapping ribbon conformations for the three largest amplitude principal components (p = 1, 2, 3) are shown with the reference structure (red) as displacements scaled by a factor of 200 standard deviations along each principal component (blue) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0009180#pone.0009180-Molecular1" target="_blank">[74]</a>.</p

Full MD results for PMF profiles.

<p>PMFs for PDC109/a (A) and PDC109/b (B) are displayed, including those in overlapping regions of windows.</p

Distances between the ligand and protein interaction sites in PDC109 domains.

<p>Time series are shown for distances between the quaternary ammonium nitrogen of PhC and the center of geometry of six carbon atoms in indole rings of W47 (A), W93 (B), W58 (C), W106 (D); and between the average position of anionic PhC phosphoryl oxygens and the hydroxyl oxygens of Y30 (E), Y75 (F), Y54 (G), Y100 (H), Y60 (I), Y108 (J).</p

Stereoviews of the homodimer crystal structure of PDC109 complexed with PhCs (PDB ID: 1h8p) [24].

<p>(A) BSP-A1 protomer and (B) BSP-A2 protomer. Bound PhC molecules are shown as vdW spheres, aromatic sidechains at the PhC binding sites are shown in orange, and loops 1 and 2 that neighbor the binding sites and interact with PhC ligand are denoted in green <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0009180#pone.0009180-Molecular1" target="_blank">[74]</a>.</p

Projections of the principal components on the normal modes for PDC109.

<p>(A) p = 1, (B) p = 2, and (C) p = 3. Insets show a magnified view for low frequency modes.</p