ABSTRACT
Chiral molecules, which selectively target and inhibit amyloid ß-peptide (Aß) aggregation, have potential use as therapeutic agents for the treatment of Alzheimer's disease (AD). Here we use cysteine enantiomer-modified SeNPs (abbreviated as d/lSeNPs) to demonstrate that surface chirality strongly influences the formation of Aß aggregates in the presence of metal ions, such as Zn2+ or Cu2+. The two chiral molecule modified nanoparticles could inhibit the formation of Aß fibrils by binding Aß, thus blocking the formation of Aß fibrils and blocking the metal binding sites. Of the two enantiomers, d/SeNPs appear to more effectively inhibit Aß fibril formation due to a greater affinity for Aß than that of l/SeNPs. Additionally, d/lSeNPs appeared to reduce Aß and metal ion-induced neurotoxicity. Treatment with d/lSeNPs can also decrease the levels of intracellular reactive oxygen species, and stabilize the mitochondrial membrane potential. Of the two enantiomers, d/SeNPs were more effective in protecting the cells than l/SeNPs, and this could be due to d/SeNPs being selectively absorbed by PC12 cells, maintaining cellular redox potentials, and protecting cells against oxidative stress to a greater extent than l/SeNPs. From these results, it appears that chiral molecules can bring novel insight into better drug treatment designs for Alzheimer's disease.
ABSTRACT
The utility of small interfering RNAs (siRNAs) has shown great promise in treating a variety of diseases including many types of cancer. While their ability to silence a wide range of target genes underlies their effectiveness, the application of therapies remains hindered by a lack of an effective delivery system. In this study, we sought to develop an siRNA-delivery system for VEGF, a known signaling molecule involved in cancer, that consists of two selenium nanoparticles SeNPs and G2/PAH-Cit/SeNPs. A G2/PAH-Cit/SeNP is a pH-sensitive delivery system that is capable of enhancing siRNA loading, thus increasing siRNA release efficiency and subsequent target gene silencing both in vitro and in vivo. In vivo experiments using G2/PAH-Cit/SeNPs@siRNA led to significantly higher accumulation of siRNA within the tumor itself, VEGF gene silencing, and reduced angiogenesis in the tumor. Furthermore, the G2/PAH-Cit/SeNP delivery system not only enhanced anti-tumor effects on tumor-bearing nude mice as compared to SeNPs@siRNA, but also resulted in weak occurrence of lesions in major target organs. In sum, this study provides a new class of siRNA delivery system, thereby providing an alternative therapeutic route for cancer treatment.
Subject(s)
Gene Silencing , Metal Nanoparticles/chemistry , Selenium/chemistry , Vascular Endothelial Growth Factor A/chemistry , Animals , Cell Line, Tumor , Cell Survival , Gene Transfer Techniques , HeLa Cells , Hep G2 Cells , Human Umbilical Vein Endothelial Cells , Humans , Hydrogen-Ion Concentration , Inhibitory Concentration 50 , Male , Mice , Mice, Inbred C57BL , Mice, Nude , Mice, SCID , Microscopy, Confocal , Microscopy, Electron, Transmission , Microscopy, Fluorescence , Neoplasm Transplantation , Neoplasms/metabolism , Neovascularization, Pathologic , RNA, Small Interfering/metabolismABSTRACT
Studies have shown that ruthenium complexes have relatively strong anticancer activity, cell uptake of drugs have a crucial impact on the pharmacological activity, using autofluorescence of ruthenium complexes could effectively track cancer cells and drug distribution, transport accurately in real time. In this work, we present the synthesis and detailed characterization of two novel Ru(II) complexes with hydrophobic ancillary ligands, namely [Ru(bpy)2(5-idip)](2+) (RBD) and [Ru(phen)2(5-idip)](2+) (RPD) (5-idip = 2-indole-[4,5-f][1,10]phenanthroline). We have shown that RPD can enter the HeLa cells efficiently through non-endocytotic, but energy-dependent mechanism and first accumulated in lysosomes, and then escape from the lysosomes and localize within the nuclei, efficiently lead to the inhibition of DNA transcription and translation and induced cell apoptosis. Further studies on the mechanism of apoptosis in HeLa cells demonstrate that RPD is able to induce mitochondria-mediated apoptosis in HeLa cells through activation of initiator caspase-9 and down-stream effector caspase-3 and -7 and cleavage of PARP. We have also demonstrated that RPD bind to telomeric G-quadruplex DNA effectively and selectively, together with increased p21 and p16 expression. Our findings suggest that RPD induces HeLa cell apoptosis through mitochondria-mediated pathway and inhibition of telomerase activity. RPD may be a candidate for further evaluation as a chemotherapeutic agent for human cancers.
Subject(s)
Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Coordination Complexes/pharmacology , Pyridines/chemistry , Ruthenium/chemistry , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Coordination Complexes/chemical synthesis , Coordination Complexes/chemistry , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor , HeLa Cells , Hep G2 Cells , Humans , Mice , Molecular Conformation , NIH 3T3 Cells , Structure-Activity RelationshipABSTRACT
A new Ru(II)-Se complex, Ru(bpy)2L2Cl2 (bpy = 2,2'-bipyridine, L = 1,10-phenanthrolineselenazole) (Ru-Se) has been synthesized and characterized. The G-quadruplex DNA-binding properties of the complex and its selenium ligand (Phen-Se) were evaluated by thermal denaturation study, polymerase chain reaction (PCR) stop assay, and telomerase repeat amplification protocol (TRAP). The results showed that the obtained complex could induce and stabilize G-quadruplex structure as well as exhibit potent inhibitory activity against telomerase. In vitro cytotoxicity studies showed that complex Ru-Se inhibited the cancer cell growth through apoptosis. However, the presence of the ligand Phen-Se did not appear to have a significant effect either on G-quadruplex binding or on biological activity. Furthermore, the cell migration assay and the tube formation assay also demonstrated that the complex Ru-Se significantly inhibited human umbilical vascular endothelial cell (HUVEC) proliferation, migration, and tube formation. These findings indicate that the Ru-Se complex may be a potential telomerase inhibitor and a viable drug candidate in antiangiogenesis for anticancer therapies.
Subject(s)
Angiogenesis Inhibitors/pharmacology , Coordination Complexes/pharmacology , G-Quadruplexes/drug effects , Organoselenium Compounds/chemistry , Ruthenium/chemistry , Telomere/drug effects , 2,2'-Dipyridyl/chemistry , Angiogenesis Inhibitors/chemical synthesis , Angiogenesis Inhibitors/chemistry , Apoptosis/drug effects , Cell Line, Tumor , Cell Movement/drug effects , Cell Survival/drug effects , Coordination Complexes/chemical synthesis , Coordination Complexes/chemistry , Human Umbilical Vein Endothelial Cells , Humans , Ligands , Molecular Conformation , Nucleic Acid Denaturation/drug effects , Phenanthrolines/chemistry , Telomere/geneticsABSTRACT
Two ruthenium(II) complexes [Ru(IP)2(PIP)](ClO4)2·2H2O (1) and [Ru(PIP)2(IP)](ClO4)2·2H2O (2) (IP=imidazole [4, 5-f] [1,10] phenanthroline, PIP=2-phenylimidazo-[4, 5-f][1,10] phenanthroline) have been synthesized and characterized. The quadruplex binding of the compounds was evaluated by emission spectrum, CD spectroscopy, Visual detection assay and FRET (fluorescence resonance energy transfer)-melting assay. The results show that both complexes can induce the stabilization of quadruplex DNA, while complex 1 is a better G-quadruplex binder than complex 2. Furthermore, polymerase chain reaction-stop assay, electrophoretic mobility shift assay, telomerase repeat amplification protocol and MTT (3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay demonstrate that complex 1 not only can stabilize dimer forms of the G-quadruplex at low concentrations but also exhibit better inhibitory activity for telomerase and cancer cells.
