Evaluation of the antitumor activity of NOV202, a novel microtubule targeting and vascular disrupting agent

Purpose: Overall, similar to 65% of patients diagnosed with advanced ovarian cancer (OC) will relapse after primary surgery and adjuvant first-line platinum-and taxane-based chemotherapy. Significant improvements in the treatment of OC are expected from the development of novel compounds having combined cytotoxic and antiangiogenic properties that make them effective on refractory tumors.Methods: Permeability of NOV202 was determined with Caco-2 monolayer assay. The compound's pharmacokinetic profile and plasma: brain distribution were assessed in male C57Bl/6 mice. The compound's impacts on tubulin, microtubules and cell cycle were investigated by using in vitro tubulin polymerization assay, cell-based immunofluorescence and live cell microscopy. The IC50 concentrations of NOV202 were assessed in a panel of eight cancer cell lines. Impact of the compound on vascular tube formation was determined using the StemKit and Chick chorioallantoic membrane assays. The in vivo efficacy of the compound was analyzed with an OC xenograft mouse model.Results: NOV202 was found to suppress cancer cell proliferation at low nanomolar concentrations (IC50 2.3-12.0 nM) and showed equal efficacy between OC cell line A2780 (IC50 2.4 nM) and its multidrug-resistant subline A2780/Adr (IC50 2.3 nM). Mechanistically, NOV202 targeted tubulin polymerization in vitro in a dose-dependent manner and in cells induced an M phase arrest. In vivo, NOV202 caused a dose-dependent reduction of tumor mass in an A2780 xenograft model, which at the highest dose (40 mg/kg) was comparable to the effect of paclitaxel (24 mg/kg). Interestingly, NOV202 exhibited vascular disrupting properties that were similar to the effects of Combretastatin A4.Conclusion: NOV202 is a novel tubulin and vascular targeting agent that shows strong anticancer efficacy in cells and OC xenograft models. The finding that the compound induced significantly more cell death in Pgp/MDR1 overexpressing OC cells compared to vincristine and paclitaxel warrants further development of the compound as a new therapy for OC patients with treatment refractory tumors and/or relapsing disease

High frequency of TTK mutations in microsatellite-unstable colorectal cancer and evaluation of their effect on spindle assembly checkpoint

Frameshift mutations frequently accumulate in microsatellite-unstable colorectal cancers (MSI CRCs) typically leading to downregulation of the target genes due to nonsense-mediated messenger RNA decay. However, frameshift mutations that occur in the 3' end of the coding regions can escape decay, which has largely been ignored in previous works. In this study, we characterized nonsense-mediated decay-escaping frameshift mutations in MSI CRC in an unbiased, genome wide manner. Combining bioinformatic search with expression profiling, we identified genes that were predicted to escape decay after a deletion in a microsatellite repeat. These repeats, located in 258 genes, were initially sequenced in 30 MSI CRC samples. The mitotic checkpoint kinase TTK was found to harbor decay-escaping heterozygous mutations in exon 22 in 59% (105/179) of MSI CRCs, which is notably more than previously reported. Additional novel deletions were found in exon 5, raising the mutation frequency to 66%. The exon 22 of TTK contains an A(9)-G(4)-A(7) locus, in which the most common mutation was a mononucleotide deletion in the A(9) (c.2560delA). When compared with identical non-coding repeats, TTK was found to be mutated significantly more often than expected without selective advantage. Since TTK inhibition is known to induce override of the mitotic spindle assembly checkpoint (SAC), we challenged mutated cancer cells with the microtubule-stabilizing drug paclitaxel. No evidence of checkpoint weakening was observed. As a conclusion, heterozygous TTK mutations occur at a high frequency in MSI CRCs. Unexpectedly, the plausible selective advantage in tumourigenesis does not appear to be related to SAC

Mesoporous Carbon Microfibers for Electroactive Materials Derived from Lignocellulose Nanofibrils

The growing adoption of biobased materials for electronic, energy conversion, and storage devices has relied on high-grade or refined cellulosic compositions. Herein, lignocellulose nanofibrils (LCNF), obtained from simple mechanical fibrillation of wood, are proposed as a source of continuous carbon microfibers obtained by wet spinning followed by single-step carbonization at 900 °C. The high lignin content of LCNF (∼28% based on dry mass), similar to that of the original wood, allowed the synthesis of carbon microfibers with a high carbon yield (29%) and electrical conductivity (66 S cm–1). The incorporation of anionic cellulose nanofibrils (TOCNF) enhanced the spinnability and the porous morphology of the carbon microfibers, making them suitable platforms for electrochemical double layer capacitance (EDLC). The increased loading of LCNF in the spinning dope resulted in carbon microfibers of enhanced carbon yield and conductivity. Meanwhile, TOCNF influenced the pore evolution and specific surface area after carbonization, which significantly improved the electrochemical double layer capacitance. When the carbon microfibers were directly applied as fiber-shaped supercapacitors (25 F cm–3), they displayed a remarkably long-term electrochemical stability (>93% of the initial capacitance after 10 000 cycles). Solid-state symmetric fiber supercapacitors were assembled using a PVA/H2SO4 gel electrolyte and resulted in an energy and power density of 0.25 mW h cm–3 and 65.1 mW cm–3, respectively. Overall, the results indicate a green and facile route to convert wood into carbon microfibers suitable for integration in wearables and energy storage devices and for potential applications in the field of bioelectronics.</p

Plasmodium APC3 mediates chromosome condensation and cytokinesis during atypical mitosis in male gametogenesis

The anaphase promoting complex/cyclosome (APC/C) is a highly conserved multi-subunit E3 ubiquitin ligase that controls mitotic division in eukaryotic cells by tagging cell cycle regulators for proteolysis. APC3 is a key component that contributes to APC/C function. Plasmodium, the causative agent of malaria, undergoes atypical mitotic division during its life cycle. Only a small subset of APC/C components has been identified in Plasmodium and their involvement in atypical cell division is not well understood. Here, using reverse genetics we examined the localisation and function of APC3 in Plasmodium berghei. APC3 was observed as a single focus that co-localised with the centriolar plaque during asexual cell division in schizonts, whereas it appeared as multiple foci in male gametocytes. Functional studies using gene disruption and conditional knockdown revealed essential roles of APC3 during these mitotic stages with loss resulting in a lack of chromosome condensation, abnormal cytokinesis and absence of microgamete formation. Overall, our data suggest that Plasmodium utilises unique cell cycle machinery to coordinate various processes during ndomitosis, and this warrants further investigation in future studies

Advantage of rare infanticide strategies in an invasion experiment of behavioural polymorphism

Killing conspecific infants (infanticide) is among the most puzzling phenomena in nature. Stable polymorphism in such behaviour could be maintained by negative frequency-dependent selection (benefit of rare types). However, it is currently unknown whether there is genetic polymorphism in infanticidal behaviour or whether infanticide may have any fitness advantages when rare. Here we show genetic polymorphism in non-parental infanticide. Our novel invasion experiment confirms negative frequency-dependent selection in wild bank vole populations, where resource benefits allow an infanticidal strategy to invade a population of non-infanticidal individuals. The results show that infanticidal behaviour is highly heritable with genetic correlation across the sexes. Thus, a positive correlative response in male behaviour is expected when selection operates on females only and vice versa. Our results, on one hand, demonstrate potential benefits of infanticide, and on the other, they open a new perspective of correlative evolution of infanticide in females and males

Towards a resolution of some outstanding issues in transitive research: an empirical test on middle childhood

Transitive Inference (deduce B > D from B > C and C > D) can help us to understand other areas of sociocognitive development. Across three experiments, learning, memory, and the validity of two transitive paradigms were investigated. In Experiment 1 (N = 121), 7-year-olds completed a three-term nontraining task or a five-term task requiring extensive-training. Performance was superior on the three-term task. Experiment 2 presented 5–10-year-olds with a new five-term task, increasing learning opportunities without lengthening training (N = 71). Inferences improved, suggesting children can learn five-term series rapidly. Regarding memory, the minor (CD) premise was the best predictor of BD-inferential performance in both task-types. However, tasks exhibited different profiles according to associations between the major (BC) premise and BD inference, correlations between the premises, and the role of age. Experiment 3 (N = 227) helped rule out the possible objection that the above findings simply stemmed from three-term tasks with real objects being easier to solve than computer-tasks. It also confirmed that, unlike for five-term task (Experiments 1 & 2), inferences on three-term tasks improve with age, whether the age range is wide (Experiment 3) or narrow (Experiment 2). I conclude that the tasks indexed different routes within a dual-process conception of transitive reasoning: The five-term tasks indexes Type 1 (associative) processing, and the three-term task indexes Type 2 (analytic) processing. As well as demonstrating that both tasks are perfectly valid, these findings open up opportunities to use transitive tasks for educability, to investigate the role of transitivity in other domains of reasoning, and potentially to benefit the lived experiences of persons with developmental issues

The Chromosomal Passenger Complex and a Mitotic Kinesin Interact with the Tousled-Like Kinase in Trypanosomes to Regulate Mitosis and Cytokinesis

Aurora B kinase plays essential roles in mitosis and cytokinesis in eukaryotes. In the procyclic form of Trypanosoma brucei, the Aurora B homolog TbAUK1 regulates mitosis and cytokinesis, phosphorylates the Tousled-like kinase TbTLK1, interacts with two mitotic kinesins TbKIN-A and TbKIN-B and forms a novel chromosomal passenger complex (CPC) with two novel proteins TbCPC1 and TbCPC2. Here we show with time-lapse video microscopy the time course of CPC trans-localization from the spindle midzone in late anaphase to the dorsal side of the cell where the anterior end of daughter cell is tethered, and followed by a glide toward the posterior end to divide the cell, representing a novel mode of cytokinesis in eukaryotes. The three subunits of CPC, TbKIN-B and TbTLK1 interact with one another suggesting a close association among the five proteins. An ablation of TbTLK1 inhibited the subsequent trans-localization of CPC and TbKIN-B, whereas a knockdown of CPC or TbKIN-B disrupted the spindle pole localization of TbTLK1 during mitosis. In the bloodstream form of T. brucei, the five proteins also play essential roles in chromosome segregation and cytokinesis and display subcellular localization patterns similar to that in the procyclic form. The CPC in bloodstream form also undergoes a trans-localization during cytokinesis similar to that in the procyclic form. All together, our results indicate that the five-protein complex CPC-TbTLK1-TbKIN-B plays key roles in regulating chromosome segregation in the early phase of mitosis and that the highly unusual mode of cytokinesis mediated by CPC occurs in both forms of trypanosomes

Aurora B potentiates Mps1 activation to ensure rapid checkpoint establishment at the onset of mitosis

The mitotic checkpoint prevents mitotic exit until all chromosomes are attached to spindle microtubules. Aurora B kinase indirectly invokes this checkpoint by destabilizing incorrect attachments; however, a more direct role remains controversial. In contrast, activity of the kinase Mps1 is indispensible for the mitotic checkpoint. Here we show that Aurora B and Hec1 are needed for efficient Mps1 recruitment to unattached kinetochores, allowing rapid Mps1 activation at the onset of mitosis. Live monitoring of cyclin B degradation reveals that this is essential to establish the mitotic checkpoint quickly at the start of mitosis. Delayed Mps1 activation and checkpoint establishment upon Aurora B inhibition or Hec1 depletion are rescued by tethering Mps1 to kinetochores, demonstrating that Mps1 recruitment is the primary role of Aurora B and Hec1 in mitotic checkpoint signalling. These data demonstrate a direct role for Aurora B in initiating the mitotic checkpoint rapidly at the onset of mitosis