Quantum dot conjugates for targeted silencing of bcr/abl gene by RNA interference in human myelogenous leukemia K562 cells

Biomaterials for polynucleotide delivery to anchorage-independent cells

Comparison of various chemical vectors used for polynucleotide delivery to mammalian anchorage-independent cells.

siRNA-cell-penetrating peptides complexes as a combinatorial therapy against chronic myeloid leukemia using BV173 cell line as model

Chronic myeloid leukemia (CML) is a myeloproliferative disorder caused by a single gene mutation, a reciprocal translocation that originates the Bcr-Abl gene with constitutive tyrosine kinase activity. As a monogenic disease, it is an optimum target for RNA silencing therapy. We developed a siRNA-based therapeutic approach in which the siRNA is delivered by pepM or pepR, two cell-penetrating peptides (CPPs) derived from the dengue virus capsid protein. These peptides have a dual role: siRNA delivery into cells and direct action as bioportides, i.e. intracellularly bioactive CPPs, targetting cancer-related signaling processes. Both pepM and pepR penetrate the positive Bcr-Abl⁺ Cell Line (BV173). Five in silico designed anti-Bcr-Abl siRNA were selected for in vitro analysis after thorough screening. The Bcr-Abl downregulation kinetics (48h to 168h) was followed by quantitative PCR. The bioportide action of the peptide vectors was evaluated by genome-wide microarray analysis and further validated by testing BV173 cell cycle and cell proliferation monitoring different genes involved in housekeeping/cell stress (RPL13A, HPRT1), cell proliferation (ki67), cell apoptosis (Caspase 3 and Caspase 9) and cell cycle steps (CDK2, CCDN2, CDKN1A). Assays with a commercial transfection agent were carried out for comparison purposes. Maximal Bcr-Abl gene knockdown was observed for one of the siRNA when delivered by pepM at 120h. Both pepM and pepR showed downregulation effects on proliferative CML-related signaling pathways having direct impact on BV173 cell cycle and proliferation, thus reinforcing the siRNA effect by acting as anticancer molecules. With this work we show the therapeutic potential of a CPP shuttle that combines intrinsic anticancer properties with the ability to deliver functional siRNA into CML cell models. By such combination, the pepM-siRNA conjugates lowered Bcr-Abl gene expression levels more extensively than conventional siRNA delivery technologies and perturbed leukemogenic cell homeostasis, hence revealing their potential as novel alternative scaffolds for CML therapy.

Revisiting 30 years of biofunctionalization and surface chemistry of inorganic nanoparticles for nanomedicine

In the last 30 years we have assisted to a massive advance of nanomaterials in material science. Nanomaterials and structures, in addition to their small size, have properties that differ from those of larger bulk materials, making them ideal for a host of novel applications. The spread of nanotechnology in the last years has been due to the improvement of synthesis and characterization methods on the nanoscale, a field rich in new physical phenomena and synthetic opportunities. In fact, the development of functional nanoparticles has progressed exponentially over the past two decades. This work aims to extensively review 30 years of different strategies of surface modification and functionalization of noble metal (gold) nanoparticles, magnetic nanocrystals and semiconductor nanoparticles, such as quantum dots. The aim of this review is not only to provide in-depth insights into the different biofunctionalization and characterization methods, but also to give an overview of possibilities and limitations of the available nanoparticles.

c-Abl phosphorylates E6AP and regulates its E3 ubiquitin ligase activity

In human papillomavirus (HPV)-infected cells, the p53 tumor suppressor is tightly regulated by the HPV-E6-E6AP complex, which promotes it for proteasomal degradation. We previously demonstrated that c-Abl tyrosine kinase protects p53 from HPV-E6-E6AP complex-mediated ubiquitination and degradation under stress conditions. However, the underlying mechanism was not defined. In this study, we explored the possibility that c-Abl targets E6AP and thereby protects p53. We demonstrated that c-Abl interacts with and phosphorylates E6AP. We determined that the E3 ligase activity of E6AP is impaired in response to phosphorylation by c-Abl. We mapped the phosphorylation site to tyrosine 636 within the HECT catalytic domain of E6AP, and using substitution mutants, we showed that this residue dictates the E3 ligase activity of E6AP, in a substrate-specific manner. On the basis of the crystal structure of the HECT domain of E6AP, we propose a model in which tyrosine 636 plays a regulatory role in the oligomerization of E6AP, which is a process implicated in its E3 ubiquitin ligase activity. Our results suggest that c-Abl protects p53 from HPV-E6-E6AP complex-mediated degradation by phosphorylating E6AP and impairing its E3 ligase activity, thus providing a molecular explanation for the stress-induced protection of p53 in HPV-infected cells.

Application of quantum dot nanoparticles for potential non-invasive bio-imaging of mammalian spermatozoa

Background

Various obstacles are encountered by mammalian spermatozoa during their journey through the female genital tract, and only few or none will reach the site of fertilization. Currently, there are limited technical approaches for non-invasive investigation of spermatozoa migration after insemination. As the knowledge surrounding sperm behavior throughout the female genital tract still remains elusive, the recent development of self-illuminating quantum dot nanoparticles may present a potential means for real-time in vitro and in vivo monitoring of spermatozoa.

Results

Here, we show the ability of boar spermatozoa to harmlessly interact and incorporate bioluminescent resonance energy transfer-conjugated quantum dot (BRET-QD) nanoparticles. The confocal microscope revealed in situ fluorescence of BRET-QD in the entire spermatozoon, while the ultra-structural analysis using the transmission electron microscope indicated BRET-QD localization on the sperm plasma membrane and intracellular compartment. In controlled-in vitro assays, bioluminescent imaging demonstrated that spermatozoa incubated with BRET-QD and luciferase substrate (coelenterazine) emit light (photons/sec) above the background, which confirmed the in situ fluorescence imaging. Most importantly, sperm motility, viability, and fertilizing potential were not affected by the BRET-QD incorporation when used at an appropriated ratio.

Conclusions

Our results demonstrate that pig spermatozoa can incorporate BRET-QD nanoparticles without affecting their motility and capacity to interact with the oocyte when used at an appropriated balance. We anticipate that our study will enable in-depth exploration of the male components of in vivo migration, fertilization, and embryonic development at the molecular level using this novel approach.

Semiconductor quantum dots for biomedicial applications

Semiconductor quantum dots (QDs) are nanometre-scale crystals, which have unique photophysical properties, such as size-dependent optical properties, high fluorescence quantum yields, and excellent stability against photobleaching. These properties enable QDs as the promising optical labels for the biological applications, such as multiplexed analysis of immunocomplexes or DNA hybridization processes, cell sorting and tracing, in vivo imaging and diagnostics in biomedicine. Meanwhile, QDs can be used as labels for the electrochemical detection of DNA or proteins. This article reviews the synthesis and toxicity of QDs and their optical and electrochemical bioanalytical applications. Especially the application of QDs in biomedicine such as delivering, cell targeting and imaging for cancer research, and in vivo photodynamic therapy (PDT) of cancer are briefly discussed.

Delivery of intracellular-acting biologics in pro-apoptotic therapies

The recent elucidation of molecular regulators of apoptosis and their roles in cellular oncogenesis has motivated the development of biomacromolecular anticancer therapeutics that can activate intracellular apoptotic signaling pathways. Pharmaceutical scientists have employed a variety of classes of biologics toward this goal, including antisense oligodeoxynucleotides, small interfering RNA, proteins, antibodies, and peptides. However, stability in the in vivo environment, tumor-specific biodistribution, cell internalization, and localization to the intracellular microenvironment where the targeted molecule is localized pose significant challenges that limit the ability to directly apply intracellular-acting, pro-apoptotic biologics for therapeutic use. Thus, approaches to improve the pharmaceutical properties of therapeutic biomacromolecules are of great significance and have included chemically modifying the bioactive molecule itself or formulation with auxiliary compounds. Recently, promising advances in delivery of pro-apoptotic biomacromolecular agents have been made using tools such as peptide "stapling", cell penetrating peptides, fusogenic peptides, liposomes, nanoparticles, smart polymers, and synergistic combinations of these components. This review will discuss the molecular mediators of cellular apoptosis, the respective mechanisms by which these mediators are dysregulated in cellular oncogenesis, the history and development of both nucleic-acid and amino-acid based drugs, and techniques to achieve intracellular delivery of these biologics. Finally, recent applications where pro-apoptotic functionality has been achieved through delivery of intracellular-acting biomacromolecular drugs will be highlighted.