Cuprous Oxide-Based Dual Catalytic Nanostructures for Tumor Vascular Normalization-Enhanced Chemodynamic Therapy

The abnormal blood vessels in tumor sites, causing poor tumor perfusion and hypoxia environment, restrict the chemodynamic therapy (CDT) potency significantly. To attain the synergistic therapy of tumor vascular normalization with CDT, herein, we constructed a dual-functional nanocatalyst with a simple structure, cuprous oxide by dextran (Cu2O@Dex), to restore proper tumor perfusion and tumor oxygenation. The in vitro experiment outcomes illustrated that Cu2O@Dex hardly releases Cu (Cu+/2+) under neutral conditions, which avoids unnecessary catalytic reaction in blood circulation. Under the weak acidic condition (pH 6.5), Cu2O@Dex begins to release Cu (Cu+/2+), catalyzing the nitric oxide (NO) generation for vascular normalization. Also, Cu2O@Dex further releases a large amount of Cu (Cu+/2+) under more acidic intratumor cells (pH 5.5), fast catalyzing the hydroxyl radical (·OH) generation for CDT. The in vivo experiment observations verified that Cu2O@Dex could improve tumor perfusion significantly 3 h post injection, which lasted for more than 144 h. The effective perfusion (Hoechst 33342+) area in the Cu2O@Dex group was 3.8-fold higher than that in the phosphate buffer saline (PBS) group after 48 h of injection, confirming the effectiveness of Cu2O@Dex to induce vascular normalization. Noticeably, tumor vascular normalization further enhanced the therapeutic effect of CDT through delivery of H2O2 generator juglone (JUG) more smoothly. The antitumor efficacy of Cu2O@Dex plus JUG was 86.5% with no obvious toxicity. Overall, our design achieved the dual-catalytic effects integrated in one simple nanostructure for tumor vascular normalization-enhanced CDT

The Crystal Structure of <em>Arabidopsis</em> VSP1 Reveals the Plant Class C-Like Phosphatase Structure of the DDDD Superfamily of Phosphohydrolases

<div><p><em>Arabidopsis thaliana</em> vegetative storage proteins, VSP1 and VSP2, are acid phosphatases and belong to the haloacid dehalogenase (HAD) superfamily. In addition to their potential nutrient storage function, they were thought to be involved in plant defense and flower development. To gain insights into the architecture of the protein and obtain clues about its function, we have tested their substrate specificity and solved the structure of VSP1. The acid phosphatase activities of these two enzymes require divalent metal such as magnesium ion. Conversely, the activity of these two enzymes is inhibited by vanadate and molybdate, but is resistant to inorganic phosphate. Both VSP1 and VSP2 did not exhibit remarkable activities to any physiological substrates tested. In the current study, we presented the crystal structure of recombinant VSP1 at 1.8 Å resolution via the selenomethionine single-wavelength anomalous diffraction (SAD). Specifically, an α-helical cap domain on the top of the α/β core domain is found to be involved in dimerization. In addition, despite of the low sequence similarity between VSP1 and other HAD enzymes, the core domain of VSP1 containing conserved active site and catalytic machinery displays a classic haloacid dehalogenase fold. Furthermore, we found that VSP1 is distinguished from bacterial class C acid phosphatase P4 by several structural features. To our knowledge, this is the first study to reveal the crystal structure of plant vegetative storage proteins.</p> </div

Electron map of VSP1.

<p>Electron map of VSP1.</p

Statistics of Data Reduction and Structure Refinement.

a<p>Data for the highest resolution bin is in parentheses.</p>b<p><i>R</i>_merge = Σ|Ii−Im|/ΣIi, where Ii is the intensity of the measured reflection and Im is the mean intensity of all symmetry-related reflections.</p>c<p><i>R</i>_work = Σ| |Fobs|−|Fcalc| |/Σ|Fobs|, where Fobs and Fcalc are observed and calculated structure factors, respectively. <i>R</i>_free = Σ_T| |Fobs|−|Fcalc| |/Σ_T|Fobs|, where T denotes a test data set of about 5% of the total reflections randomly chosen and set aside prior to refinement.</p>d<p>RMSD = root-mean-square deviation.</p

Temporal changes in three parameters of CDOM composition: molecular size (<i>MS</i>), spectral slope (<i>S</i>), and spectral slope ratio (<i>S</i>_R) of WDA (a, c, e) and PDA (b, d, f) CDOM samples.

<p>Temporal changes in three parameters of CDOM composition: molecular size (<i>MS</i>), spectral slope (<i>S</i>), and spectral slope ratio (<i>S</i>_R) of WDA (a, c, e) and PDA (b, d, f) CDOM samples.</p

Relative activities of VSP1 and VSP2 toward different substrates.

<p>ND, not detectable.</p><p>Relative activities are expressed as the percentage of the activity with <i>p</i>NPP. The results are the average of the values determined in triplicates and the respective standard error is constantly lower than 10%.</p

Temporal changes in total dissolved nitrogen concentration (TDN), total dissolved phosphorus concentration (TDP), and the ratio of TDN to TDP, for WDA (a–c) and PDA (d–f) CDOM samples exposed to natural solar radiation.

<p>Except for the initial value (0d), each measurement is an average of three samples (true replicates). Error bars indicate standard deviation.</p

Structural comparison of VSP1 and P4.

<p>(A) Topology of VSP1. (B) Topology of P4. (C) Superposition of VSP1 and P4 (stereo view). In (A) (B) (C), an additional α helix in P4 (yellow) is marked by a rectangle. Longer N-terminus in VSP1 (cyan) is colored blue, while longer C-terminus in P4 is colored magenta. Structural elements of P4 in (B) are labeled based on the structural alignment with VSP1. (D) NMN binding with P4. NMN is shown in sticks model. Important residues of P4 interacting with NMN are labeled. (E) Superpose VSP1 to P4 while NMN is modeled at the same site as in P4. Corresponding residues in VSP1 are labeled. NMN is shown in sticks model.</p

Kinetic parameters for VSP1 protein with different divalent metal ions.

<p>Data represent the means±SD from three independent assays.</p

Comparison between VSP1 and P4 in active sites and dimer patterns.

<p>(A) Residues in the catalytic site of VSP1. Magnesium ions and water molecules are colored by green and red, respectively. (B) Residues in the catalytic site of P4. Magnesium ion and water molecules are colored by green and red, respectively. (C) Hydrophobic core between two VSP1 monomers. Two VSP1 monomers are colored magenta and cyan, respectively. (D) Hydrogen bonds between two VSP1 monomers. Two VSP1 monomers are colored magenta and cyan, respectively. (E) Interaction pattern of VSP1 dimer. One monomer is coloured magenta, while the N-terminal helices of the other monomer are coloured cyan. (F) Interaction pattern of P4 dimer. One monomer is colored yellow, while the N-terminal helices of the other monomer are colored green. The magenta VSP1 monomer in (E) and the yellow P4 monomer in (F) are aligned.</p