Antibody-Targeted Cyclodextrin-Based Nanoparticles for siRNA Delivery in the Treatment of Acute Myeloid Leukemia: Physicochemical Characteristics, in Vitro Mechanistic Studies, and ex Vivo Patient Derived Therapeutic Efficacy.

Acute myeloid leukemia (AML) is the most common type of acute leukemia in adults and is associated with high relapse rates. It is known that leukemia stem cells (LSCs), a very small subpopulation of the total number of leukemic cells, maintain the leukemia phenotype (∼80-90% of AML remain the same as at first diagnosis), display chemotherapy resistance, and contribute to disease regeneration. Therefore, targeting LSCs could control the relapse of AML. Small interfering RNA (siRNA), an effector of the RNA interference (RNAi) pathway, can selectively downregulate any gene implicated in the pathology of disease, presenting great potential for treatment of AML. In this study an antibody targeted cyclodextrin-based nanoparticle (NP) (CD.DSPE-PEG-Fab) was developed for siRNA delivery specifically to AML LSCs. The targeted CD.siRNA.DSPE-PEG-Fab formulation, where Fab specifically targets the IL-3 receptor α-chain (IL-3Rα, also known as CD123, a cell surface antigen for human AML LSCs), achieved antigen-mediated cellular uptake in KG1 cells (an AML leukemia stem and progenitor cell line). Efficient delivery of bromodomain-containing protein 4 (BRD4) siRNA using the targeted formulation resulted in downregulation of the corresponding mRNA and protein in KG1 cells and in ex vivo primary AML patient derived samples. The resulting silencing of BRD4 induced myeloid differentiation and triggered leukemia apoptosis. In addition, a synergistic therapeutic effect was detected when administered in combination with the chemotherapeutic, cytarabine (Ara-C). These results indicate the clinical potential of the antibody-tagged cyclodextrin NP for targeted delivery of therapeutic siRNA in the treatment of AML.

7-formyl-10-methylisoellipticine, a novel ellipticine derivative, induces mitochondrial reactive oxygen species (ROS) and shows anti-leukaemic activity in mice.

Acute myeloid leukaemia (AML) is the most common type of leukaemia in adults and is associated with high relapse rates. Current treatment options have made significant progress but the 5 year survival for AML remains low and therefore, there is an urgent need to develop novel therapeutics. Ellipticines, a class of cancer chemotherapeutic agents, have had limited success clinically due to low solubility and toxic side effects. Isoellipticines, novel isomers of ellipticine, have been designed to overcome these limitations. One particular isoellipticine, 7-formyl-10-methylisoellipticine, has previously showed strong ability to inhibit the growth of leukaemia cell lines. In this study the anti-leukaemia effect of this compound was investigated in detail on an AML cell line, MV4-11. Over a period of 24 h 7-formyl-10-methyl isoellipticine at a concentration of 5 µM can kill up to 40 % of MV4-11 cells. Our research suggests that the cytotoxicity of 7-formyl-10-methylisoellipticine is partially mediated by an induction of mitochondrial reactive oxygen species (ROS). Furthermore, 7-formyl-10-methylisoellipticine demonstrated promising anti-tumour activity in an AML xenograft mouse model without causing toxicity, implying the potential of isoellipticines as novel chemotherapeutic agents in the treatment of leukaemia.

New Insight into the Role of Reactive Oxygen Species (ROS) in Cellular Signal-Transduction Processes.

Reactive oxygen species (ROS) were once considered to be deleterious agents, contributing to a vast range of pathologies. But, now their protective effects are being appreciated. Both their damaging and beneficial effects are initiated when they target distinct molecules and consequently begin functioning as part of complex signal-transduction pathways. The recognition of ROS as signaling mediators has driven a wealth of research into their roles in both normal and pathophysiological states. The present review assesses the relevant recent literature to outline the current perspectives on redox-signaling mechanisms, physiological implications, and therapeutic strategies. This study highlights that a more fundamental knowledge about many aspects of redox signaling will allow better targeting of ROS, which would in turn improve prophylactic and pharmacotherapy for redox-associated diseases.

NADPH oxidase-generated hydrogen peroxide induces DNA damage in mutant FLT3-expressing leukemia cells.

Internal tandem duplication of the FMS-like tyrosine kinase (FLT3-ITD) receptor is present in 20% of acute myeloid leukemia (AML) patients and it has been associated with an aggressive AML phenotype. FLT3-ITD expressing cell lines have been shown to generate increased levels of reactive oxygen species (ROS) and DNA double strand breaks (DSBs). However, the molecular basis of how FLT3-ITD-driven ROS leads to the aggressive form of AML is not clearly understood. Our group has previously reported that inhibition of FLT3-ITD signaling results in post-translational down-regulation of p22(phox), a small membrane-bound subunit of the NADPH oxidase (NOX) complex. Here we demonstrated that 32D cells, a myeloblast-like cell line transfected with FLT3-ITD, have a higher protein level of p22(phox) and p22(phox)-interacting NOX isoforms than 32D cells transfected with the wild type FLT3 receptor (FLT3-WT). The inhibition of NOX proteins, p22(phox), and NOX protein knockdowns caused a reduction in ROS, as measured with a hydrogen peroxide (H2O2)-specific dye, peroxy orange 1 (PO1), and nuclear H2O2, as measured with nuclear peroxy emerald 1 (NucPE1). These reductions in the level of H2O2 following the NOX knockdowns were accompanied by a decrease in the number of DNA DSBs. We showed that 32D cells that express FLT3-ITD have a higher level of both oxidized DNA and DNA DSBs than their wild type counterparts. We also observed that NOX4 and p22(phox) localize to the nuclear membrane in MV4-11 cells expressing FLT3-ITD. Taken together these data indicate that NOX and p22(phox) mediate the ROS production from FLT3-ITD that signal to the nucleus causing genomic instability.

From iron pentacarbonyl to the iron ion by imaging photoelectron photoion coincidence.

The dissociation dynamics of internal energy selected iron pentacarbonyl cations, Fe(CO)5(+), have been investigated using the imaging photoelectron photoion coincidence (iPEPICO) spectrometer at the Swiss Light Source. The molecular ion loses all five carbonyl ligands in sequential dissociations in the 8.5-20 eV photon energy range. The Fe(CO)5(+) parent ion is metastable at the onset of the first dissociation reaction on the time scale of the experiment. The slightly asymmetric and broad daughter ion time-of-flight distributions indicate parent ion lifetimes in the microsecond range, and are used to obtain an experimental dissociation rate curve. Further carbonyl losses were found to be fast at threshold. The fractional parent and daughter ion abundances as a function of the photon energy, that is, breakdown diagram, as well as the dissociation rates for the first CO loss were modeled using the statistical Rice-Ramsperger-Kassel-Marcus (RRKM) and statistical adiabatic channel model (SSACM) theories. The excess energy redistribution in the products was also taken into account in a statistical framework. The 0 K dissociative photoionization thresholds for the five carbonyl-loss channels were found to be 9.015 ± 0.024 eV, 10.199 ± 0.027 eV, 10.949 ± 0.033 eV, 12.282 ± 0.39 eV, and 13.821 ± 0.045 eV for the processes leading to Fe(CO)4(+), Fe(CO)3(+), Fe(CO)2(+), Fe(CO)(+), and Fe(+), respectively. The iron cation thermochemistry is well-known, and these onsets connect the bare metal ion to the other fragment ions as well as to the gas phase neutral Fe(CO)5.

Inhibition of the Pim1 oncogene results in diminished visual function.

Our objective was to profile genetic pathways whose differential expression correlates with maturation of visual function in zebrafish. Bioinformatic analysis of transcriptomic data revealed Jak-Stat signalling as the pathway most enriched in the eye, as visual function develops. Real-time PCR, western blotting, immunohistochemistry and in situ hybridization data confirm that multiple Jak-Stat pathway genes are up-regulated in the zebrafish eye between 3-5 days post-fertilisation, times associated with significant maturation of vision. One of the most up-regulated Jak-Stat genes is the proto-oncogene Pim1 kinase, previously associated with haematological malignancies and cancer. Loss of function experiments using Pim1 morpholinos or Pim1 inhibitors result in significant diminishment of visual behaviour and function. In summary, we have identified that enhanced expression of Jak-Stat pathway genes correlates with maturation of visual function and that the Pim1 oncogene is required for normal visual function.