A convenient protonated strategy for constructing nanodrugs from hydrophobic drug-inhibitor conjugates to reverse tumor multidrug resistance.

Combination therapy has proven effective in counteracting tumor multidrug resistance (MDR). However, the pharmacokinetic differences among various drugs and inherent water insolubility for most small molecule agents greatly hinder their synergistic effects, which makes the delivery of drugs for combination therapy in vivo a key problem. Herein, we propose a protonated strategy to transform a water-insoluble small molecule drug-inhibitor conjugate into an amphiphilic one, which then self-assembles into nanoparticles for co-delivery in vivo to overcome tumor MDR. Specifically, paclitaxel (PTX) is first coupled with a third-generation P-glycoprotein (P-gp) inhibitor zosuquidar (Zos) through a glutathione (GSH)-responsive disulfide bond to produce a hydrophobic drug-inhibitor conjugate (PTX-ss-Zos). Subsequently treated with hydrochloric acid ethanol solution (HCl/EtOH), PTX-ss-Zos is transformed into the amphiphilic protonated precursor and then forms nanoparticles (PTX-ss-Zos@HCl NPs) in water by molecular self-assembly. PTX-ss-Zos@HCl NPs can be administered intravenously and accumulated specifically at tumor sites. Once internalized by cancer cells, PTX-ss-Zos@HCl NPs can be degraded under the overexpressed GSH to release PTX and Zos simultaneously, which synergistically reverse tumor MDR and inhibit tumor growth. This offers a promising strategy to develop small molecule self-assembled nanoagents to reverse tumor MDR in combination therapy.

Pioneering 4,11-Dioxo-4,11-dihydro-1H-anthra[2,3-d]imidazol-3-ium Compounds as Promising Survivin Inhibitors by Targeting ILF3/NF110 for Cancer Therapy.

Survivin is a novel attractive target for cancer therapy; however, it is considered undruggable because it lacks enzymatic activities. Herein, we describe our efforts toward the discovery of a novel series of 4,11-dioxo-4,11-dihydro-1H-anthra[2,3-d]imidazol-3-ium derivatives as survivin inhibitors by targeting ILF3/NF110. Intensive structural modifications led us to identify a lead compound AQIM-I, which remarkably inhibited nonsmall cell lung cancer cells A549 with an IC50 value of 9 nM and solid tumor cell proliferation with more than 700-fold selectivity against human normal cells. Further biological studies revealed that compound AQIM-I significantly inhibited survivin expression and colony formation and induced ROS production, apoptosis, cell cycle arrest, DNA damage, and autophagy. Furthermore, the promoter-luciferase reporter assay showed that AQIM-I attenuated the survivin promoter activity enhanced by the overexpression of ILF3/NF110 in a concentration-dependent manner, and specific binding (KD = 163 nM) of AQIM-I to ILF3/NF110 was detected by surface plasmon resonance.

Redox-responsive drug-inhibitor conjugate encapsulated in DSPE-PEG2k micelles for overcoming multidrug resistance to chemotherapy.

Multidrug resistance (MDR) is a major cause of chemotherapy failure in cancer treatment. P-glycoprotein (P-gp) inhibitors are helpful for chemotherapy drugs to overcome tumor MDR effectively. With the traditional physical mixing of chemotherapy drugs and inhibitors, it is difficult to achieve satisfactory results due to the different pharmacokinetics and physicochemical properties between the two of them. Herein, we prepared a novel drug-inhibitor conjugate prodrug (PTX-ss-Zos) from a cytotoxin (PTX) and a third-generation P-gp inhibitor (Zos) linked with a redox-responsive disulfide. Then, PTX-ss-Zos was encapsulated in DSPE-PEG2k micelles to form stable and uniform nanoparticles (PTX-ss-Zos@DSPE-PEG2k NPs). PTX-ss-Zos@DSPE-PEG2k NPs could be cleaved by the high-concentration GSH in cancer cells and release PTX and Zos simultaneously to inhibit MDR tumor growth synergistically without apparent systemic toxicity. The in vivo evaluation experiments exhibited that the tumor inhibition rates (TIR) of PTX-ss-Zos@DSPE-PEG2k NPs were high up to 66.5% for HeLa/PTX tumor-bearing mice. This smart nanoplatform would bring new hope for cancer treatment in clinical trials.

Self-Assembled Nanomicelles of Affibody-Drug Conjugate with Excellent Therapeutic Property to Cure Ovary and Breast Cancers.

Affibody molecules are small non-immunoglobulin affinity proteins, which can precisely target to some cancer cells with specific overexpressed molecular signatures. However, the relatively short in vivo half-life of them seriously limited their application in drug targeted delivery for cancer therapy. Here an amphiphilic affibody-drug conjugate is self-assembled into nanomicelles to prolong circulation time for targeted cancer therapy. As an example of the concept, the nanoagent was prepared through molecular self-assembly of the amphiphilic conjugate of ZHER2:342-Cys with auristatin E derivate, where the affibody used is capable of binding to the human epidermal growth factor receptor 2 (HER2). Such a nanodrug not only increased the blood circulation time, but also enhanced the tumor targeting capacity (abundant affibody arms on the nanoagent surface) and the drug accumulation in tumor. As a result, this affibody-based nanoagent showed excellent antitumor activity in vivo to HER2-positive ovary and breast tumor models, which nearly eradicated both small solid tumors (about 100 mm3) and large established tumors (exceed 500  mm3). The relative tumor proliferation inhibition ratio reaches 99.8% for both models.

Improving Targeted Delivery and Antitumor Efficacy with Engineered Tumor Necrosis Factor-Related Apoptosis Ligand-Affibody Fusion Protein.

Tumor necrosis factor-related apoptosis ligand (TRAIL) is a promising protein candidate for selective apoptosis of a variety of cancer cells. However, the short half-life and a lack of targeted delivery are major obstacles for its application in cancer therapy. Here, we propose a simple strategy to solve the targeting problem by genetically fusing an anti-HER2 affibody to the C-terminus of the TRAIL. The fusion protein TRAIL-affibody was produced as a soluble form with high yield in recombinant Escherichia coli. In vitro studies proved that the affibody domain promoted the cellular uptake of the fusion protein in the HER2 overexpressed SKOV-3 cells and improved its apoptosis-inducing ability. In addition, the fusion protein exhibited higher accumulation at the tumor site and greater antitumor effect than those of TRAIL in vivo, indicating that the affibody promoted the tumor homing of the TRAIL and then improved the therapeutic efficacy. Importantly, repeated injection of high-dose TRAIL-affibody showed no obvious toxicity in mice. These results demonstrated that the engineered TRAIL-affibody is promising to be a highly tumor-specific and targeted cancer therapeutic agent.

ROS-Responsive Nanoparticles Formed from RGD-Epothilone B Conjugate for Targeted Cancer Therapy.

The targeted nanoagents have shown great potential clinically for cancer therapy. Traditional targeted nanodrugs are usually prepared through surface postmodification. Herein, a nanodrug is self-assembled from the amphiphilic precursor of targeting peptide RGD conjugated with cytotoxin epothilone B (Epo B) through a linker containing the thioketal (tk) group that is sensitive to reactive oxygen species (ROS). The obtained RGD-tk-Epo B conjugate nanoparticles (RECNs) are stable and uniform, which facilitates improving tumor-targeting capacity and accumulation of the drug because of the large number of RGD on the surface of the RECN. After internalization by cancer cells, the blood-inert tk group between RGD and Epo B can be cleaved in the presence of high level of ROS to release Epo B, exhibiting a markedly tumor selectivity and excellent anticancer efficiency in vitro and in vivo.

Integration of multiple active sites on large-pore mesoporous silica for enantioselective tandem reactions.

Facile construction of a multifunctional heterogeneous catalyst through the assembly of Au/carbene and chiral ruthenium/diamine dual complexes in large-pore mesoporous silica was developed. This enables an efficient one-pot hydration-asymmetric transfer hydrogenation enantioselective tandem reaction of haloalkynes, affording chiral halohydrins with up to 99% enantioselectivity. Combined multifunctionalities, such as substrate-promoted silanol-functionality, BF4- anion-bonding gold/carbene and covalent-bonding chiral ruthenium/diamine active centers, contributed cooperatively to the catalytic performance.