Microfluidized Dextran Microgels Loaded with Cisplatin/SPION Lipid Nanotherapeutics for Local Colon Cancer Treatment via Oral Administration.

Multifunctional sequential targeted delivery system is developed as an efficient therapeutic strategy against malignant tumors with selective accumulation and minimal systemic drug absorption. The therapeutic system is comprised of microfluidized dextran microgels encapsulating cisplatin/superparamagnetic iron oxide nanoparticles (SPIONs)-loaded trilaurin-based lipid nanoparticles (LNPs). The microgel system is imparted hierarchically dual targeting via dextran and folic acid (FA) residues, leading to increases both in retention of the microgels in colon and in cellular uptake of the therapeutic LNPs by colon cancer cells while being used for oral therapeutic delivery. Encapsulation of the therapeutic LNPs into dextran microgels attained by microfluidized crosslinking reaction reduces gastrointestinal adhesion and prevents the FA-modified LNPs from cellular transport by proton-coupled FA transporters in small intestine during their oral delivery to colon. Upon enzymatic degradation of the dextran microgels by dextranase present exclusively in colon, LNPs thus released become more recognizable and readily internalized by FA receptor-overexpressing colon cancer cells. The combined chemo/magnetothermal therapeutic effect of dual targeted lipid nanoparticle-loaded microgels from entrapped lipidized cisplatin and alternating magnetic field-treated SPIONs significantly inhibits tumor growth and suppresses metastatic peritoneal carcinomatosis in orthotopic colon cancer-bearing mice.

Tumor microenvironment-responsive and oxygen self-sufficient oil droplet nanoparticles for enhanced photothermal/photodynamic combination therapy against hypoxic tumors.

The combination of photothermal and photodynamic therapy (PTT/PDT) shows pronounced potential as a prominent therapeutic strategy for tumor treatment. However, the efficacy is limited by insufficient tumor-targeted delivery of PTT and PDT reagents and the hypoxic nature of the tumor microenvironment. To overcome these limitations, tumor acidity-responsive lipid membrane-enclosed perfluorooctyl bromide oil droplet nanoparticles (NPs) surface modified with N-acetyl histidine-modified D-α-tocopheryl polyethylene glycol 1000 succinate (PFOB@IMHNPs) were developed, capable of co-delivering oxygen, IR780 (a photothermal agent) and mTHPC (a photodynamic sensitizer) into tumors. Through self-sufficient oxygen transportation in combination with promotion of cellular uptake upon acid-triggered generation of surface positive charge, the PFOB@IMHNPs effectively delivered IR780 and mTHPC and produced singlet oxygen within hypoxic TRAMP-C1 cells following exposure to irradiation at 660 nm. This led to effective killing of hypoxic cancer cells in vitro. Importantly, when irradiation at 808 and 660 nm was carried out, PT/PD combination therapy utilizing PFOB@IMHNPs dramatically suppressed the growth of TRAMP-C1 tumors through effective tumor-targeted cargo delivery and relief of tumor hypoxia. Our results suggest the high potential of the PFOB@IMHNPs developed in this study in clinical application for cancer treatment.

New combination treatment from ROS-Induced sensitized radiotherapy with nanophototherapeutics to fully eradicate orthotopic breast cancer and inhibit metastasis.

Radiotherapy (RT) is one of the most commonly employed approaches in the treatment of malignant tumors and is often combined with radiosensitizers to enhance the therapeutic efficacy for clinical use. For developing a smart therapeutic strategy leveraging local tissue response to photo-mediated reactions and the combination of multiple treatment modalities involving ROS-induced sensitization of RT, a novel nanophototherapeutic system has been developed. The nanotherapeutics prepared from the assembly of poly (thiodiethylene malonate) (PSDEM) and PEG-PSDEM-PEG and loaded with suberoylanilide hydroxamic acid (SAHA) employed as the RT sensitizer and indocyanine green (ICG) as the photothermal/photodynamic agent, demonstrated the capability of undergoing structural change and releasing therapeutic payloads in response to near-infrared irradiation and X-ray radiotherapy. With highly localized and controllable reactions within the tumor site, the reactive oxygen species (ROS)-triggered SAHA unloading and the hyperthermia-induced vascular permeability of oxygen led to a significant sensitization of the target tissue in RT, which, in turn, led to the promotion of therapeutic effect in conjunction with photodynamic/photothermal therapies (PDT/PTT). In vitro studies demonstrated the damage in intracellular DNA double strands and the inhibition of cell proliferation in 4T1 breast cancer cells treated with ROS-induced sensitized RT. A substantial reduction in cell viability was also observed owing to the effects of the combination of photo-mediated treatments with sensitized RT compared to the effects of RT administration alone. Complete eradication of the primary tumor and the inhibition of lung metastasis was observed in five of six orthotopic 4T1 breast cancer-bearing mice subjected to combined PDT/PTT in nanophototherapeutics with ROS-induced sensitized RT at a low dosage (6 Gy), leading to the prominent survival fraction of ca. 83% over 60 days.

Capturing Amyloid-ß Oligomers by Stirring with Microscaled Iron Oxide Stir Bars into Magnetic Plaques to Reduce Cytotoxicity toward Neuronal Cells.

Soluble amyloid-ß oligomers (oAß42)-induced neuronal death and inflammation response has been recognized as one of the major causes of Alzheimer's disease (AD). In this work, a novel strategy adopting silica-coated iron oxide stir bar (MSB)-based AD therapy system via magnetic stirring-induced capture of oAß42 into magnetic plaques (mpAß42) and activation of microglia on cellular plaque clearance was developed. With oAß42 being effectively converted into mpAß42, the neurotoxicity toward neuronal cells was thus greatly reduced. In addition to the good preservation of neurite outgrowth through the diminished uptake of oAß42, neurons treated with oAß42 under magnetic stirring also exhibited comparable neuron-specific protein expression to those in the absence of oAß42. The phagocytic uptake of mpAß42 by microglia was enhanced significantly as compared to the counterpart of oAß42, and the M1 polarization of microglia often occurring after the uptake of oAß42 restricted to an appreciable extent. As a result, the inflammation induced by pro-inflammatory cytokines was greatly alleviated.

Indocyanine green/doxorubicin-encapsulated functionalized nanoparticles for effective combination therapy against human MDR breast cancer.

To overcome low therapeutic efficacy of chemotherapy against multidrug resistance (MDR) breast cancer, a combination therapy system based upon functionalized polymer nanoparticles comprising poly(γ-glutamic acid)-g-poly(lactic-co-glycolic acid) (γ-PGA-g-PLGA) as the major component was developed. The NPs were loaded with doxorubicin (DOX) and indocyanine green (ICG) for dual modality cancer treatment and coated with cholesterol-PEG (C-PEG) for MDR abrogation in treatment of human MDR breast cancer. The in vitro cellular uptake of the DOX/ICG loaded nanoparticles (DI-NPs) by MDR cancer cells was significantly enhanced owing to effective inhibition of the P-gp activity by C-PEG and γ-PGA receptor-mediated endocytosis. DOX localization in cytoplasm and nucleus was observed particularly with the photo-thermal effect that facilitated intracellular drug release. As a result, the C-PEG coated DI-NPs after photo-irradiation exhibited a synergistic effect of combination (chemo/thermal) therapy to depress the proliferation of MDR cancer calls. The ex vivo biodistribution study revealed an enhanced tumor accumulation of C-PEG (2000) coated DI-NPs in MCF-7/MDR tumor-bearing nude mice due to the excellent EPR effects by the NP surface PEGylation. The MDR tumor growth was almost entirely inhibited in the group receiving combination therapy from CP2k-DI-NPs and photo-irradiation along with substantial cell apoptosis of tumor tissues examined by immunohistochemical staining. The results demonstrate a promising dual modality therapy system, CP2k-DI-NPs, developed in this work for effective combination therapy of human MDR breast cancer.

Tumortropic adipose-derived stem cells carrying smart nanotherapeutics for targeted delivery and dual-modality therapy of orthotopic glioblastoma.

Chemotherapy is typically used to treat malignant brain tumors, especially for the tumors in surgically inaccessible areas. However, owing to the existence of blood-brain barrier (BBB), the tumor accumulation and therapeutic efficacy of clinical therapeutics is still of great concerns. To this end, we present herein a prominent therapeutic strategy adopting adipose-derived stem cells (ADSCs) capable of carrying nanotherapeutic payloads selectively toward brain tumors for thermo/chemotherapy. The nanoparticle (NP) payload was obtained from co-assembly of poly(γ-glutamic acid-co-distearyl γ-glutamate) with poly(lactic-co-glycolic acid), paclitaxel (PTX), and oleic acid-coated superparamagnetic iron oxide NPs in aqueous solution. The particle size and drug loading content were ca 110nm and 8.4wt%, respectively. After being engulfed by ADSCs, the nanotherapeutics was found rather harmless to cellular hosts at a PTX concentration of 30µM over 48h in the absence of pertinent stimulus. Nevertheless, the ADSC-based approach combined with high frequency magnetic field exhibits a sound therapeutic performance with a 4-fold increase in therapeutic index on brain astrocytoma (ALTS1C1)-bearing mice (C57BL/6J) as compared to the typical chemotherapy using a current first-line chemodrug, temozolomide. Immunohistochemical examination of brain tumor sections confirms the successful cellular transport and pronounced cytotoxic action of therapeutics against tumor cells in vivo. This work demonstrates the promise of ADSC-mediated chemo/thermal therapy against brain tumors.

Protein-specific scoring method for ligand discovery.

Protein-based virtual screening plays an important role in modern drug discovery process. Most protein-based virtual screening experiments are carried out with docking programs. The accuracy of a docking program highly relies on the incorporated scoring function based on various energy terms. The existing scoring functions deal all the energy terms with the equal weight function or other weight function derived by physical characteristics. These existing scoring functions are not protein dependent. We expect that a protein-specific scoring function, which can reflect the protein characteristics, may improve the docking results. Therefore, we propose a protein-specific rescoring approach to select potential ligands by adjusting the weights of energy terms. The protein-specific scoring function is based on the linear regression analysis associated with an outlier detection approach. The scoring function incorporated in DOCK program is used as the model system. The performance of our method was evaluated by the DUD docked data set, which contains 40 protein targets. The study results show that this method can improve the enrichment factors for most of the 40 protein targets. We further expend the protein-specific scoring function to a larger database, and the results also show significant improvement. Our method is not limited to improving the DOCK scoring function. It can be adopted to improve other programs such as GOLD and Glide. We believe that this method can be applied to virtual screening experiments and elevates the hits rate significantly, which can be beneficial to the modern drug discovery process.

Structure-based inhibitors exhibit differential activities against Helicobacter pylori and Escherichia coli undecaprenyl pyrophosphate synthases.

Helicobacter pylori colonizes the human gastric epithelium and causes diseases such as gastritis, peptic ulcers, and stomach cancer. Undecaprenyl pyrophosphate synthase (UPPS), which catalyzes consecutive condensation reactions of farnesyl pyrophosphate with eight isopentenyl pyrophosphate to form lipid carrier for bacterial peptidoglycan biosynthesis, represents a potential target for developing new antibiotics. In this study, we solved the crystal structure of H. pylori UPPS and performed virtual screening of inhibitors from a library of 58,635 compounds. Two hits were found to exhibit differential activities against Helicobacter pylori and Escherichia coli UPPS, giving the possibility of developing antibiotics specially targeting pathogenic H. pylori without killing the intestinal E. coli.

A three-dimensional pharmacophore model for dipeptidyl peptidase IV inhibitors.

Dipeptidyl peptidase IV (DPP-IV) is a valid drug target for type-2 diabetes and DPP-IV inhibitors have been proven to efficiently improve glucose tolerance. In our study, 3D pharmacophore models were generated using a training set of 22 DPP-IV inhibitors. The best model consisted of important chemical features and mapped well into the active site of DPP-IV. The model gave high correlation coefficients of 0.97 and 0.84 for the training set and the test set, respectively, showing its good predictive ability for biological activity. Furthermore, the pharmacophore model demonstrated the capability to retrieve inhibitors from database with a high enrichment factor of 42.58. All results suggest that the model provides a useful tool for designing novel DPP-IV inhibitors.

Structural basis for the structure-activity relationships of peroxisome proliferator-activated receptor agonists.

Type 2 diabetes has rapidly reached an epidemic proportion becoming a major threat to global public health. PPAR agonists have emerged as a leading class of oral antidiabetic drugs. We report a structure biology analysis of novel indole-based PPAR agonists to explain the structure-activity relationships and present a critical analysis of reasons for change in selectivity with change in the orientation of the same scaffolds. The results would be helpful in designing novel PPAR agonists.

Structure-based drug design and structural biology study of novel nonpeptide inhibitors of severe acute respiratory syndrome coronavirus main protease.

Severe acute respiratory syndrome coronavirus (SARS-CoV) main protease (M(pro)), a protein required for the maturation of SARS-CoV, is vital for its life cycle, making it an attractive target for structure-based drug design of anti-SARS drugs. The structure-based virtual screening of a chemical database containing 58,855 compounds followed by the testing of potential compounds for SARS-CoV M(pro) inhibition leads to two hit compounds. The core structures of these two hits, defined by the docking study, are used for further analogue search. Twenty-one analogues derived from these two hits exhibited IC50 values below 50 microM, with the most potent one showing 0.3 microM. Furthermore, the complex structures of two potent inhibitors with SARS-CoV M(pro) were solved by X-ray crystallography. They bind to the protein in a distinct manner compared to all published SARS-CoV M(pro) complex structures. They inhibit SARS-CoV M(pro) activity via intensive H-bond network and hydrophobic interactions, without the formation of a covalent bond. Interestingly, the most potent inhibitor induces protein conformational changes, and the inhibition mechanisms, particularly the disruption of catalytic dyad (His41 and Cys145), are elaborated.

Discovery of a novel family of SARS-CoV protease inhibitors by virtual screening and 3D-QSAR studies.

The severe acute respiratory syndrome-associated coronavirus (SARS-CoV) 3C-like protease (3CL(pro) or M(pro)) is an attractive target for the development of anti-SARS drugs because of its crucial role in the viral life cycle. In this study, a compound database was screened by the structure-based virtual screening approach to identify initial hits as inhibitors of SARS-CoV 3CL(pro). Out of the 59,363 compounds docked, 93 were selected for the inhibition assay, and 21 showed inhibition against SARS-CoV 3CL(pro) (IC(50)

Structure-based drug design of a novel family of PPARgamma partial agonists: virtual screening, X-ray crystallography, and in vitro/in vivo biological activities.

Peroxisome proliferator-activated receptor gamma (PPARgamma) is well-known as the receptor of thiazolidinedione antidiabetic drugs. In this paper, we present a successful example of employing structure-based virtual screening, a method that combines shape-based database search with a docking study and analogue search, to discover a novel family of PPARgamma agonists based upon pyrazol-5-ylbenzenesulfonamide. Two analogues in the family show high affinity for, and specificity to, PPARgamma and act as partial agonists. They also demonstrate glucose-lowering efficacy in vivo. A structural biology study reveals that they both adopt a distinct binding mode and have no H-bonding interactions with PPARgamma. The absence of H-bonding interaction with the protein provides an explanation why both function as partial agonists since most full agonists form conserved H-bonds with the activation function helix (AF-2 helix) which, in turn, enhances the recruitment of coactivators. Moreover, the structural biology and computer docking studies reveal the specificity of the compounds for PPARgamma could be due to the restricted access to the binding pocket of other PPAR subtypes, i.e., PPARalpha and PPARdelta, and steric hindrance upon the ligand binding.

Indol-1-yl acetic acids as peroxisome proliferator-activated receptor agonists: design, synthesis, structural biology, and molecular docking studies.

A series of novel indole-based PPAR agonists is described leading to discovery of 10k, a highly potent PPAR pan-agonist. The structural biology and molecular docking studies revealed that the distances between the acidic group and the linker, when a ligand was complexed with PPARgamma protein, were important for the potent activity. The hydrophobic tail part of 10k makes intensive hydrophobic interaction with the PPARgamma protein resulting in potent activity.

2-[3-[2-[(2S)-2-Cyano-1-pyrrolidinyl]-2-oxoethylamino]-3-methyl-1-oxobutyl]- 1,2,3,4-tetrahydroisoquinoline: a potent, selective, and orally bioavailable dipeptide-derived inhibitor of dipeptidyl peptidase IV.

Dipeptidyl peptidase IV (DPP-IV) inhibitors are expected to become a new type of antidiabetic drugs. Most known DPP-IV inhibitors often resemble the dipeptide cleavage products, with a proline mimic at the P1 site. As off-target inhibitions of DPP8 and/or DPP9 have shown profound toxicities in the in vivo studies, it is important to develop selective DPP-IV inhibitors for clinical usage. To achieve this, a new class of 2-[3-[[2-[(2S)-2-cyano-1-pyrrolidinyl]-2-oxoethyl]amino]-1-oxopropyl]-based DPP-IV inhibitors was synthesized. SAR studies resulted in a number of DPP-IV inhibitors, having IC(50) values of <50 nM with excellent selectivity over both DPP8 (IC(50) > 100 microM) and DPP-II (IC(50) > 30 microM). Compound 21a suppressed the blood glucose elevation after an oral glucose challenge in Wistar rats and also inhibited plasma DPP-IV activity for up to 4 h in BALB/c mice. The results show that compound 21a possesses in vitro and in vivo activities comparable to those of NVP-LAF237 (4), which is in clinical development.

Novel indole-based peroxisome proliferator-activated receptor agonists: design, SAR, structural biology, and biological activities.

The synthesis and structure-activity relationship studies of novel indole derivatives as peroxisome proliferator-activated receptor (PPAR) agonists are reported. Indole, a drug-like scaffold, was studied as a core skeleton for the acidic head part of PPAR agonists. The structural features (acidic head, substitution on indole, and linker) were optimized first, by keeping benzisoxazole as the tail part, based on binding and functional activity at PPARgamma protein. The variations in the tail part, by introducing various heteroaromatic ring systems, were then studied. In vitro evaluation led to identification of a novel series of indole compounds with a benzisoxazole tail as potent PPAR agonists with the lead compound 14 (BPR1H036) displaying an excellent pharmacokinetic profile in BALB/c mice and an efficacious glucose lowering activity in KKA(y) mice. Structural biology studies of 14 showed that the indole ring contributes strong hydrophobic interactions with PPARgamma and could be an important moiety for the binding to the protein.

Glutamic acid analogues as potent dipeptidyl peptidase IV and 8 inhibitors.

To find potent and selective inhibitors of dipeptidyl peptidase IV (DPP-IV), we synthesized a series of 2-cyanopyrrolidine with P2-site 4-substituted glutamic acid derivatives and tested their activities against DPP-IV, DPP8, and DPP-II. Analogues that incorporated a bulky substituent at the first carbon position of benzylamine or isoquinoline showed over 30-fold selectivity for DPP-IV over both DPP8 and DPP-II. From structure-activity relationship studies, we speculate that the S2 site of DPP8 might be similar to that of DPP-IV, while DPP-IV inhibitor with N-substituted glycine in the P2 site and/or with a moiety involving in hydrophobic interaction with the side chain of Phe357 might provide a better selectivity for DPP-IV over DPP8.