How kinesin motor proteins drive mitotic spindle function: Lessons from molecular assays

KIF2C as a potential therapeutic target: insights from lung adenocarcinoma subtype classification and functional experiments

Objective: this study evaluates the prognostic relevance of gene subtypes and the role of kinesin family member 2C (KIF2C) in lung cancer progression. Methods: high-expression genes linked to overall survival (OS) and progression-free interval (PFI) were selected from the TCGA-LUAD dataset. Consensus clustering analysis categorized lung adenocarcinoma (LUAD) patients into two subtypes, C1 and C2, which were compared using clinical, drug sensitivity, and immunotherapy analyses. A random forest algorithm pinpointed KIF2C as a prognostic hub gene, and its functional impact was assessed through various assays and in vivo experiments. Results: The study identified 163 key genes and distinguished two LUAD subtypes with differing OS, PFI, pathological stages, drug sensitivity, and immunotherapy response. KIF2C, highly expressed in the C2 subtype, was associated with poor prognosis, promoting cancer cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT), with knockdown reducing tumor growth in mice. Conclusion: The research delineates distinct LUAD subtypes with significant clinical implications and highlights KIF2C as a potential therapeutic target for personalized treatment in LUAD.

Molecular Ratchets and Kinetic Asymmetry: Giving Chemistry Direction

Over the last two decades ratchet mechanisms have transformed the understanding and design of stochastic molecular systems-biological, chemical and physical-in a move away from the mechanical macroscopic analogies that dominated thinking regarding molecular dynamics in the 1990s and early 2000s (e.g. pistons, springs, etc), to the more scale-relevant concepts that underpin out-of-equilibrium research in the molecular sciences today. Ratcheting has established molecular nanotechnology as a research frontier for energy transduction and metabolism, and has enabled the reverse engineering of biomolecular machinery, delivering insights into how molecules 'walk' and track-based synthesisers operate, how the acceleration of chemical reactions enables energy to be transduced by catalysts (both motor proteins and synthetic catalysts), and how dynamic systems can be driven away from equilibrium through catalysis. The recognition of molecular ratchet mechanisms in biology, and their invention in synthetic systems, is proving significant in areas as diverse as supramolecular chemistry, systems chemistry, dynamic covalent chemistry, DNA nanotechnology, polymer and materials science, molecular biology, heterogeneous catalysis, endergonic synthesis, the origin of life, and many other branches of chemical science. Put simply, ratchet mechanisms give chemistry direction. Kinetic asymmetry, the key feature of ratcheting, is the dynamic counterpart of structural asymmetry (i.e. chirality). Given the ubiquity of ratchet mechanisms in endergonic chemical processes in biology, and their significance for behaviour and function from systems to synthesis, it is surely just as fundamentally important. This Review charts the recognition, invention and development of molecular ratchets, focussing particularly on the role for which they were originally envisaged in chemistry, as design elements for molecular machinery. Different kinetically asymmetric systems are compared, and the consequences of their dynamic behaviour discussed. These archetypal examples demonstrate how chemical systems can be driven inexorably away from equilibrium, rather than relax towards it.

Role of microRNAs in tumor progression by regulation of kinesin motor proteins

Aberrant cell proliferation is one of the main characteristics of tumor cells that can be affected by many cellular processes and signaling pathways. Kinesin superfamily proteins (KIFs) are motor proteins that are involved in cytoplasmic transportations and chromosomal segregation during cell proliferation. Therefore, regulation of the KIF functions as vital factors in chromosomal stability is necessary to maintain normal cellular homeostasis and proliferation. KIF deregulations have been reported in various cancers. MicroRNAs (miRNAs) and signaling pathways are important regulators of KIF proteins. MiRNAs have key roles in regulation of the cell proliferation, migration, and apoptosis. In the present review, we discussed the role of miRNAs in tumor biology through the regulation of KIF proteins. It has been shown that miRNAs have mainly a tumor suppressor function via the KIF targeting. This review can be an effective step to introduce the miRNAs/KIFs axis as a probable therapeutic target in tumor cells.

KIF15 promotes the development and progression of chordoma via activating PI3K-AKT signalling pathway

Aims

Despite its implication in various human cancers, the expression and functional significance of Kinesin family member 15 (KIF15) in chordomas remain unexplored.

Main methods

The evaluation of KIF15 protein levels was conducted through immunohistochemistry (IHC) staining and Western blot analysis. Cell proliferation was quantified using MTT and CCK8 assays, whereas cell migration was examined using wound healing and Transwell assays. Furthermore, flow cytometric analysis was utilized to assess cell apoptosis and the cell cycle. Additionally, in vivo experiments were performed using a mouse xenograft model.

Key findings

Our study revealed significantly higher expression of KIF15 in stage III chordoma tissues compared to stage II tissues. Knockdown of KIF15 led to notable inhibition of cell proliferation and migration, along with enhanced apoptosis and cell cycle arrest. In vivo studies further confirmed the inhibitory effects of KIF15 knockdown on chordoma tumour growth. In terms of mechanism, we identified the involvement of the PI3K-AKT signalling pathway mediated by KIF15 in chordomas. Notably, the anti-tumour effects of KIF15 deficiency on chordomas were partially reversed by the addition of an AKT activator.

Significance

KIF15 promotes chordoma development and progression through the activation of the PI3K-AKT signalling pathway. Thus, targeting KIF15 might be a promising therapeutic strategy for treating chordomas.

Modeling Studies of the Mechanism of Context-Dependent Bidirectional Movements of Kinesin-14 Motors

Kinesin-14s, a subfamily of the large superfamily of kinesin motor proteins, function mainly in spindle assembly and maintenance during mitosis and meiosis. KlpA from Aspergillus nidulans and GiKIN14a from Giardia intestinalis are two types of kinesin-14s. Available experimental results puzzlingly showed that while KlpA moves preferentially toward the minus end in microtubule-gliding setups and inside parallel microtubule overlaps, it moves preferentially toward the plus end on single microtubules. More puzzlingly, the insertion of an extra polypeptide linker in the central region of the neck stalk switches the motility direction of KlpA on single microtubules to the minus end. Prior experimental results showed that GiKIN14a moves preferentially toward the minus end on single microtubules in either tailless or full-length forms. The tail not only greatly enhances the processivity but also accelerates the ATPase rate and velocity of GiKIN14a. The insertion of an extra polypeptide linker in the central region of the neck stalk reduces the ATPase rate of GiKIN14a. However, the underlying mechanism of these puzzling dynamical features for KlpA and GiKIN14a is unclear. Here, to understand this mechanism, the dynamics of KlpA and GiKIN14a were studied theoretically on the basis of the proposed model, incorporating potential changes between the kinesin head and microtubule, as well as the potential between the tail and microtubule. The theoretical results quantitatively explain the available experimental results and provide predicted results. It was found that the elasticity of the neck stalk determines the directionality of KlpA on single microtubules and affects the ATPase rate and velocity of GiKIN14a on single microtubules.

The role of kinesin family members in hepatobiliary carcinomas: from bench to bedside

As a major component of the digestive system malignancies, tumors originating from the hepatic and biliary ducts seriously endanger public health. The kinesins (KIFs) are molecular motors that enable the microtubule-dependent intracellular trafficking necessary for mitosis and meiosis. Normally, the stability of KIFs is essential to maintain cell proliferation and genetic homeostasis. However, aberrant KIFs activity may destroy this dynamic stability, leading to uncontrolled cell division and tumor initiation. In this work, we have made an integral summarization of the specific roles of KIFs in hepatocellular and biliary duct carcinogenesis, referring to aberrant signal transduction and the potential for prognostic evaluation. Additionally, current clinical applications of KIFs-targeted inhibitors have also been discussed, including their efficacy advantages, relationship with drug sensitivity or resistance, the feasibility of combination chemotherapy or other targeted agents, as well as the corresponding clinical trials. In conclusion, the abnormally activated KIFs participate in the regulation of tumor progression via a diverse range of mechanisms and are closely associated with tumor prognosis. Meanwhile, KIFs-aimed inhibitors also carry out a promising tumor-targeted therapeutic strategy that deserves to be further investigated in hepatobiliary carcinoma (HBC).

Genome-wide transcriptome analysis of Echinococcus multilocularis larvae and germinative cell cultures reveals genes involved in parasite stem cell function

The lethal zoonosis alveolar echinococcosis is caused by tumour-like growth of the metacestode stage of the tapeworm Echinococcus multilocularis within host organs. We previously demonstrated that metacestode proliferation is exclusively driven by somatic stem cells (germinative cells), which are the only mitotically active parasite cells that give rise to all differentiated cell types. The Echinococcus gene repertoire required for germinative cell maintenance and differentiation has not been characterised so far. We herein carried out Illumina sequencing on cDNA from Echinococcus metacestode vesicles, from metacestode tissue depleted of germinative cells, and from Echinococcus primary cell cultures. We identified a set of ~1,180 genes associated with germinative cells, which contained numerous known stem cell markers alongside genes involved in replication, cell cycle regulation, mitosis, meiosis, epigenetic modification, and nucleotide metabolism. Interestingly, we also identified 44 stem cell associated transcription factors that are likely involved in regulating germinative cell differentiation and/or pluripotency. By in situ hybridization and pulse-chase experiments, we also found a new general Echinococcus stem cell marker, EmCIP2Ah, and we provide evidence implying the presence of a slow cycling stem cell sub-population expressing the extracellular matrix factor Emkal1. RNA-Seq analyses on primary cell cultures revealed that metacestode-derived Echinococcus stem cells display an expanded differentiation capability and do not only form differentiated cell types of the metacestode, but also cells expressing genes specific for protoscoleces, adult worms, and oncospheres, including an ortholog of the schistosome praziquantel target, EmTRPMPZQ. Finally, we show that primary cell cultures contain a cell population expressing an ortholog of the tumour necrosis factor α receptor family and that mammalian TNFα accelerates the development of metacestode vesicles from germinative cells. Taken together, our analyses provide a robust and comprehensive characterization of the Echinococcus germinative cell transcriptome, demonstrate expanded differentiation capability of metacestode derived stem cells, and underscore the potential of primary germinative cell cultures to investigate developmental processes of the parasite. These data are relevant for studies into the role of Echinococcus stem cells in parasite development and will facilitate the design of anti-parasitic drugs that specifically act on the parasite germinative cell compartment.

More is different: Reconstituting complexity in microtubule regulation

Microtubules are dynamic cytoskeletal filaments that undergo stochastic switching between phases of polymerization and depolymerization-a behavior known as dynamic instability. Many important cellular processes, including cell motility, chromosome segregation, and intracellular transport, require complex spatiotemporal regulation of microtubule dynamics. This coordinated regulation is achieved through the interactions of numerous microtubule-associated proteins (MAPs) with microtubule ends and lattices. Here, we review the recent advances in our understanding of microtubule regulation, focusing on results arising from biochemical in vitro reconstitution approaches using purified multiprotein ensembles. We discuss how the combinatory effects of MAPs affect both the dynamics of individual microtubule ends, as well as the stability and turnover of the microtubule lattice. In addition, we highlight new results demonstrating the roles of protein condensates in microtubule regulation. Our overall intent is to showcase how lessons learned from reconstitution approaches help unravel the regulatory mechanisms at play in complex cellular environments.

ADP release can explain spatially-dependent kinesin binding times

The self-organization of cells relies on the profound complexity of protein-protein interactions. Challenges in directly observing these events have hindered progress toward understanding their diverse behaviors. One notable example is the interaction between molecular motors and cytoskeletal systems that combine to perform a variety of cellular functions. In this work, we leverage theory and experiments to identify and quantify the rate-limiting mechanism of the initial association between a cargo-bound kinesin motor and a microtubule track. Recent advances in optical tweezers provide binding times for several lengths of kinesin motors trapped at varying distances from a microtubule, empowering the investigation of competing models. We first explore a diffusion-limited model of binding. Through Brownian dynamics simulations and simulation-based inference, we find this simple diffusion model fails to explain the experimental binding times, but an extended model that accounts for the ADP state of the molecular motor agrees closely with the data, even under the scrutiny of penalizing for additional model complexity. We provide quantification of both kinetic rates and biophysical parameters underlying the proposed binding process. Our model suggests that most but not every motor binding event is limited by their ADP state. Lastly, we predict how these association rates can be modulated in distinct ways through variation of environmental concentrations and spatial distances.

Kinesin family member 11 promotes progression of hepatocellular carcinoma via the OCT4 pathway

Hepatocellular carcinoma (HCC) is the tumor with the second highest mortality rate worldwide. Recent research data show that KIF11, a member of the kinesin family (KIF), plays an important role in the progression of various tumors. However, its expression and molecular mechanism in HCC remain elusive. Here, we evaluated the potential role of KIF11 in HCC. The effect of KIF11 was evaluated using the hepatocellular carcinoma cell lines, LM3 and Huh7, after genetic or pharmacological treatment. Evaluating the role of KIF11 in the xenograft animal models using its specific inhibitor. The role of KIF11 was systematically evaluated using specimens obtained from the aforementioned animal and cell models after various in vivo and in vitro experiments. The clinicopathological analysis showed that KIF11 was expressed at high levels in patients with hepatocellular carcinoma. Cell experiments in vitro showed that KIF11 deficiency significantly slowed the proliferation of liver tumor cells. And in the experiment using liver cancer cells overexpressing OCT4, overexpression of OCT4 substantially increased the proliferation of tumor cells compared with tumor cells with KIF11 knockdown alone. Both in vitro cell experiment and in vivo xenotransplantation tumor experiment showed that monastrol, an inhibitor of KIF11, could effectively delay the proliferation and migration of tumor cells. Based on these results, KIF11 is expressed at high levels in hepatocellular carcinoma and promotes tumor proliferation in an OCT4-dependent manner. KIF11 may become a therapeutic target for hepatocellular carcinoma, and its inhibitor monastrol may become a clinical antitumor drug.

Life's Mechanism

The multifarious internal workings of organisms are difficult to reconcile with a single feature defining a state of 'being alive'. Indeed, definitions of life rely on emergent properties (growth, capacity to evolve, agency) only symptomatic of intrinsic functioning. Empirical studies demonstrate that biomolecules including ratcheting or rotating enzymes and ribozymes undergo repetitive conformation state changes driven either directly or indirectly by thermodynamic gradients. They exhibit disparate structures, but govern processes relying on directional physical motion (DNA transcription, translation, cytoskeleton transport) and share the principle of repetitive uniplanar conformation changes driven by thermodynamic gradients, producing dependable unidirectional motion: 'heat engines' exploiting thermodynamic disequilibria to perform work. Recognition that disparate biological molecules demonstrate conformation state changes involving directional motion, working in self-regulating networks, allows a mechanistic definition: life is a self-regulating process whereby matter undergoes cyclic, uniplanar conformation state changes that convert thermodynamic disequilibria into directed motion, performing work that locally reduces entropy. 'Living things' are structures including an autonomous network of units exploiting thermodynamic gradients to drive uniplanar conformation state changes that perform work. These principles are independent of any specific chemical environment, and can be applied to other biospheres.

Key essential oil components delocalize Candida albicans Kar3p and impact microtubule structure

BACKGROUND

Treatment of Candida albicans associated infections is often ineffective in the light of resistance, with an urgent need to discover novel antimicrobials. Fungicides require high specificity and can contribute to antifungal resistance, so inhibition of fungal virulence factors is a good strategy for developing new antifungals.

OBJECTIVES

Examine the impact of four plant-derived essential oil components (1,8-cineole, α-pinene, eugenol, and citral) on C. albicans microtubules, kinesin motor protein Kar3 and morphology.

METHODS

Microdilution assays were used to determine minimal inhibitory concentrations, microbiological assays assessed germ tube, hyphal and biofilm formation, confocal microscopy probed morphological changes and localization of tubulin and Kar3p, and computational modelling was used to examine the theoretical binding of essential oil components to tubulin and Kar3p.

RESULTS

We show for the first time that essential oil components delocalize the Kar3p, ablate microtubules, and induce psuedohyphal formation with reduced biofilm formation. Single and double deletion mutants of kar3 were resistant to 1,8-cineole, sensitive to α-pinene and eugenol, but unimpacted by citral. Strains with homozygous and heterozygous Kar3p disruption had a gene-dosage effect for all essential oil components, resulting in enhanced resistance or susceptibility patterns that were identical to that of cik1 mutants. The link between microtubule (αβ-tubulin) and Kar3p defects was further supported by computational modeling, showing preferential binding to αβ-tubulin and Kar3p adjacent to their Mg²⁺-binding sites.

CONCLUSION

This study highlights how essential oil components interfere with the localization of the kinesin motor protein complex Kar3/Cik1 and disrupt microtubules, leading to their destabilization which results in hyphal and biofilm defects.

DEPDC1 and KIF4A synergistically inhibit the malignant biological behavior of osteosarcoma cells through Hippo signaling pathway

The treatment of osteosarcoma (OS) is still mainly surgery combined with systematic chemotherapy, and gene therapy is expected to improve the survival rate of patients. This study aimed to explore the effect of DEP domain 1 protein (DEPDC1) and kinesin super-family protein 4A (KIF4A) in OS and understand its mechanism. Th expression of DEPDC1 and KIF4A in OS cells was detected by RT-PCR and western blot. The viability, proliferation, invasion and migration of OS cells and tube formation of human umbilical vein endothelial cells (HUVECs) after indicated treatment were in turn detected by CCK-8 assay, EdU staining, wound healing assay, transwell assay and tube formation assay. The interaction between DEPDC1 and KIF4A was predicted by STRING and confirmed by co-immunoprecipitation. The expression of epithelial-mesenchymal transition (EMT)-related proteins, tube formation-related proteins and Hippo signaling pathway proteins was detected by western blot. As a result, the expression of DEPDC1 and KIF4A was all increased in U2OS cells. Down-regulation of DEPDC1 suppressed the viability, proliferation, invasion and migration of U2OS cells and tube formation of HUVECs, accompanied by the increased expression of E-cadherin and decreased expression of N-cadherin, Vimentin and VEGF. DEPDC1 was confirmed to be interacted with KIF4A. Upregulation of KIF4A partially reversed the effect of DEPDC1 interference on the above biological behaviors of U2OS cells. Down-regulation of DEPDC1 promoted the expression of p-LATS1 and p-YAP in Hippo signaling pathway, which was reversed by upregulation of KIF4A. In conclusion, down-regulation of DEPDC1 inhibited the malignant biological behavior of OS cells through the activation of Hippo signaling pathway, which could be reversed by upregulation of KIF4A.

Expression, regulating mechanism and therapeutic target of KIF20A in multiple cancer

Kinesin family member 20A (KIF20A) is a member of the kinesin family. It transports chromosomes during mitosis, plays a key role in cell division. Recently, studies proved that KIF20A was highly expressed in cancer. High expression of KIF20A was correlated with poor overall survival (OS). In this review, we summarized all the cancer that highly expressed KIF20A, described the role of KIF20A in cancer. We also organized phase I and phase II clinical trials of KIF20A peptides vaccine. All results indicated that KIF20A was a promising therapeutic target for multiple cancer.

Electro-detachment of kinesin motor domain from microtubule in silico

Kinesin is a motor protein essential in cellular functions, such as intracellular transport and cell-division, as well as for enabling nanoscopic transport in bio-nanotechnology. Therefore, for effective control of function for nanotechnological applications, it is important to be able to modify the function of kinesin. To circumvent the limitations of chemical modifications, here we identify another potential approach for kinesin control: the use of electric forces. Using full-atom molecular dynamics simulations (247,358 atoms, total time ∼ 4.4 μs), we demonstrate, for the first time, that the kinesin-1 motor domain can be detached from a microtubule by an intense electric field within the nanosecond timescale. We show that this effect is field-direction dependent and field-strength dependent. A detailed analysis of the electric forces and the work carried out by electric field acting on the microtubule-kinesin system shows that it is the combined action of the electric field pulling on the β-tubulin C-terminus and the electric-field-induced torque on the kinesin dipole moment that causes kinesin detachment from the microtubule. It is shown, for the first time in a mechanistic manner, that an electric field can dramatically affect molecular interactions in a heterologous functional protein assembly. Our results contribute to understanding of electromagnetic field-biomatter interactions on a molecular level, with potential biomedical and bio-nanotechnological applications for harnessing control of protein nanomotors.

MAPping tubulin mutations

Microtubules are filamentous structures that play a critical role in a diverse array of cellular functions including, mitosis, nuclear translocation, trafficking of organelles and cell shape. They are composed of α/β-tubulin heterodimers which are encoded by a large multigene family that has been implicated in an umbrella of disease states collectively known as the tubulinopathies. De novo mutations in different tubulin genes are known to cause lissencephaly, microcephaly, polymicrogyria, motor neuron disease, and female infertility. The diverse clinical features associated with these maladies have been attributed to the expression pattern of individual tubulin genes, as well as their distinct Functional repertoire. Recent studies, however, have highlighted the impact of tubulin mutations on microtubule-associated proteins (MAPs). MAPs can be classified according to their effect on microtubules and include polymer stabilizers (e.g., tau, MAP2, doublecortin), destabilizers (e.g., spastin, katanin), plus-end binding proteins (e.g., EB1-3, XMAP215, CLASPs) and motor proteins (e.g., dyneins, kinesins). In this review we analyse mutation-specific disease mechanisms that influence MAP binding and their phenotypic consequences, and discuss methods by which we can exploit genetic variation to identify novel MAPs.

KIF4A drives gliomas growth by transcriptional repression of Rac1/Cdc42 to induce cytoskeletal remodeling in glioma cells

Glioma is one of the most prevalent cancers diseases in the worldwide. Kinesin superfamily protein 4 (KIF4), a KIF member classified in Kinesin 4 has been indicated as a mediator acted in tumorigenesis of human cancer. However, the mechanism of KIF4A on glioma is yet to be investigated. This study aimed to explore the potential function and mechanism of KIF4A in gliomas. We analyzed the KIF4A expression and the prognosis in gliomas patients using The Cancer Genome Atlas (TCGA) databases. KIF4A level in normal human astrocyte cell (NHA) and glioma cell lines were examined by Western blot. We studied the function of KIF4A on proliferation, migration, invasion, cell cycle in glioma cell lines using a series of in vitro and in vivo experiments. Chromatin Immunoprecipitation (ChIP) analysis was applied to searching potential KIF4A related downstream in glioma. We identified the significant up-regulated expression of KIF4A both in glioma tissues and cell. Glioma patients with elevated KIF4A expression have shorter survival. Down-regulation of KIF4A exerted inhibitory effect on cell proliferation, invasion and migration. We crucially identified that KIF4A drives gliomas growth by transcriptional repression of Rac1/Cdc42 to induce cytoskeletal remodeling in glioma cells. Knockdown of KIF4A decreased RohA, Rac1, Cdc42, Pak1 and Pak2 expression level. Our study provided a prospect that KIF4A functions as an oncogene in glioma.

Magic-angle-spinning NMR structure of the kinesin-1 motor domain assembled with microtubules reveals the elusive neck linker orientation

Microtubules (MTs) and their associated proteins play essential roles in maintaining cell structure, organelle transport, cell motility, and cell division. Two motors, kinesin and cytoplasmic dynein link the MT network to transported cargos using ATP for force generation. Here, we report an all-atom NMR structure of nucleotide-free kinesin-1 motor domain (apo-KIF5B) in complex with paclitaxel-stabilized microtubules using magic-angle-spinning (MAS) NMR spectroscopy. The structure reveals the position and orientation of the functionally important neck linker and how ADP induces structural and dynamic changes that ensue in the neck linker. These results demonstrate that the neck linker is in the undocked conformation and oriented in the direction opposite to the KIF5B movement. Chemical shift perturbations and intensity changes indicate that a significant portion of ADP-KIF5B is in the neck linker docked state. This study also highlights the unique capability of MAS NMR to provide atomic-level information on dynamic regions of biological assemblies.

Modeling Study of the Dynamics of Kinesin-14 Molecular Motors

Kinesin-14s constitute a subfamily of the large superfamily of adenosine triphosphate-dependent microtubule-based motor proteins. Kinesin-14s have the motor domain at the C-terminal end of the peptide, playing key roles during spindle assembly and maintenance. Some of them are nonprocessive motors, whereas others can move processively on microtubules. Here, we take budding yeast Cik1-Kar3 and human HSET as examples to study theoretically the dynamics of the processive kinesin-14 motor moving on the single microtubule under load, the dynamics of the motor coupled with an Ndc80 protein moving on the single microtubule, the dynamics of the motor moving in microtubule arrays, and so on. The dynamics of the nonprocessive Drosophila Ncd motor is also discussed. The studies explain well the available experimental data and, moreover, provide predicted results. We show that the processive kinesin-14 motors can move efficiently in microtubule arrays toward the minus ends, and after reaching the minus ends, they can stay there stably, thus performing the function of organizing the microtubules in the bipolar spindle into polar arrays at the spindle poles.

Integrated bioinformatics analysis of potential biomarkers for pancreatic cancer

BACKGROUND

Pancreatic cancer, particularly pancreatic ductal adenocarcinoma (PDA), is an aggressive malignancy associated with a low 5-year survival rate. Poor outcomes associated with PDA are attributable to late detection and inoperability. Most patients with PDA are diagnosed with locally advanced and metastatic disease. Such cases are primarily treated with chemotherapy and radiotherapy. Because of the lack of effective molecular targets, early diagnosis and successful therapies are limited. The purpose of this study was to screen key candidate genes for PDA using a bioinformatic approach and to research their potential functional, pathway mechanisms associated with PDA progression. It may help to understand the role of associated genes in the development and progression of PDA and identify relevant molecular markers with value for early diagnosis and targeted therapy.

MATERIALS AND METHODS

To identify novel genes associated with carcinogenesis and progression of PDA, we analyzed the microarray datasets GSE62165, GSE125158, and GSE71989 from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified, and the Database for Annotation, Visualization, and Integrated Discovery (DAVID) was used for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. A protein-protein interaction (PPI) network was constructed using STRING, and module analysis was performed using Cytoscape. Gene Expression Profiling Interactive Analysis (GEPIA) was used to evaluate the differential expression of hub genes in patients with PDA. In addition, we verified the expression of these genes in PDA cell lines and normal pancreatic epithelial cells.

RESULTS

A total of 202 DEGs were identified and these were found to be enriched for various functions and pathways, including cell adhesion, leukocyte migration, extracellular matrix organization, extracellular region, collagen trimer, membrane raft, fibronectin-binding, integrin binding, protein digestion, and absorption, and focal adhesion. Among these DEGs, 12 hub genes with high degrees of connectivity were selected. Survival analysis showed that the hub genes (HMMR, CEP55, CDK1, UHRF1, ASPM, RAD51AP1, DLGAP5, KIF11, SHCBP1, PBK, and HMGB2) may be involved in the tumorigenesis and development of PDA, highlighting their potential as diagnostic and therapeutic factors in PDA.

CONCLUSIONS

In summary, the DEGs and hub genes identified in the present study not only contribute to a better understanding of the molecular mechanisms underlying the carcinogenesis and progression of PDA but may also serve as potential new biomarkers and targets for PDA.

Optical Control of Mitosis with a Photoswitchable Eg5 Inhibitor

Eg5 is a kinesin motor protein that is responsible for bipolar spindle formation and plays a crucial role during mitosis. Loss of Eg5 function leads to the formation of monopolar spindles, followed by mitotic arrest, and subsequent cell death. Several cell-permeable small molecules have been reported to inhibit Eg5 and some have been evaluated as anticancer agents. We now describe the design, synthesis, and biological evaluation of photoswitchable variants with five different pharmacophores. Our lead compound Azo-EMD is a cell permeable azobenzene that inhibits Eg5 more potently in its light-induced cis form. This activity decreased the velocity of Eg5 in single-molecule assays, promoted formation of monopolar spindles, and led to mitotic arrest in a light dependent way.

LncRNA VPS9D1-AS1 Promotes Malignant Progression of Lung Adenocarcinoma by Targeting miRNA-30a-5p/KIF11 Axis

Objective: This research probed into the molecular mechanisms of long non-coding RNA (lncRNA) VPS9D1 Antisense RNA 1 (VPS9D1-AS1) in lung adenocarcinoma (LUAD).

Methods: lncRNA expression level was evaluated bioinformatically, and its downstream miRNA/mRNA regulatory axis was predicted by bioinformatics methods as well. qRT-PCR was used to measure VPS9D1-AS1, miRNA-30a-5p, and kinesin family member 11 (KIF11) expression. Western blot was performed to measure KIF11 protein expression. Proliferation, migration, and invasion of LUAD cells were all observed by cell biological function experiments. Dual-luciferase assay detected binding between miRNA-30a-5p and VPS9D1-AS1 or KIF11, respectively. RIP experiment detected interaction between VPS9D1-AS1 and miRNA-30a-5p.

Results: VPS9D1-AS1 and KIF11 were increased in LUAD, whereas miRNA-30a-5p was decreased. VPS9D1-AS1 promoted the malignant progression of LUAD cells and could sponge miRNA-30a-5p. MiRNA-30a-5p could restore the impact of VPS9D1-AS1 on LUAD cells. KIF11 was a target downstream of miRNA-30a-5p. VPS9D1-AS1 could upregulate KIF11 expression through competitively sponging miRNA-30a-5p, and KIF11 could restore the impact of miRNA-30a-5p on LUAD cells.

Conclusion: VPS9D1-AS1 could foster malignant progression of LUAD via regulating miRNA-30a-5p/KIF11 axis, suggesting that VPS9D1-AS1 is key to regulating the malignant progression of LUAD.

KIF4A Regulates the Progression of Pancreatic Ductal Adenocarcinoma through Proliferation and Invasion

Background

Pancreatic cancer is a malignant tumor of the digestive tract, which is difficult to diagnose and treat due to bad early diagnosis. We aimed to explore the role of kinesin superfamily 4A (KIF4A) in pancreatic ductal adenocarcinoma (PDAC).

Methods

We first used the bioinformatic website to screen the data of pancreatic cancer in TCGA, and KIF4A protein was detected among the 86 specimens of patients in our hospital combined with clinic-pathological characteristics and survival analysis. KIF4A loss-expression cell lines were established by RNA interference (RNAi). In addition, we performed in vitro cell assays to detect the changes in cell proliferation, migration, and invasion. The proteins involved in the proliferation and metastasis of cancer cells were also detected by western blot. The above results could be proved in vivo. Further, the correlation between KIF4A and CDC5L was analyzed by TCGA and IHC data.

Results

We first found a high expression of KIF4A in pancreatic cancer, suggesting a role of KIF4A in the development of pancreatic cancer. KIF4A was found to be differentially expressed (P < 0.05) among the 86 specimens of patients in our hospital and was significantly associated with PDAC TNM stages and tumor size. High KIF4A expression also significantly worsened overall survival (OS) and disease-free survival rate (DFS) (P < 0.05, respectively). In addition, cell proliferation, migration, and invasion were inhibited by the KIF4A-shRNA group compared with the control (P < 0.05, respectively). In the end, knockdown of KIF4A could inhibit tumor development and metastasis in vivo. Further, the positive correlation between KIF4A and CDC5L existed, and KIF4A might promote pancreatic cancer proliferation by affecting CDC5L expression.

Conclusion

In conclusion, the high expression level of KIF4A in PDAC was closely related to poor clinical and pathological status, lymphatic metastasis, and vascular invasion. KIF4A might be involved in promoting the development of PDAC in vitro and in vivo, which might be a new therapeutic target of PDAC.

Identification of KIF4A as a prognostic biomarker for esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is the most common and aggressive tumor worldwide, and the long-term survival of these patients remains poor. Three databases (GSE17351, GSE20347, and GSE100942) were obtained from Gene Expression Omnibus, and 193 differentially expressed genes including 56 upregulated and 137 downregulated genes were identified by paired test using limma R package. Then, functional enrichments by gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses showed these genes were mainly related protein digestion and absorption, and IL-17 signaling pathway. We then constructed a protein-protein interaction network and cytoHubba module to determine the six hub genes and overall survival analysis of the six hub genes were evaluated by UALCAN and GEPIA2 analysis. Ultimately, the experimental results confirmed the KIF4A was overexpressed in the ESCC tissues and cell lines compared with the normal esophageal mucosal tissues and was linked to poor prognosis. Moreover, we also revealed that KIF4A facilitates proliferation, cell cycle, migration, and invasion of ESCC in vivo and in vitro. Overall, these findings demonstrated that KIF4A could serve as diagnostic and prognostic biomarkers and may help facilitate therapeutic targets in ESCC patients.

Microtubule dynamics influence the retrograde biased motility of kinesin-4 motor teams in neuronal dendrites

Microtubules establish the directionality of intracellular transport by kinesins and dynein through polarized assembly, but it remains unclear how directed transport occurs along microtubules organized with mixed polarity. We investigated the ability of the plus end–directed kinesin-4 motor KIF21B to navigate mixed polarity microtubules in mammalian dendrites. Reconstitution assays with recombinant KIF21B and engineered microtubule bundles or extracted neuronal cytoskeletons indicate that nucleotide-independent microtubule-binding regions of KIF21B modulate microtubule dynamics and promote directional switching on antiparallel microtubules. Optogenetic recruitment of KIF21B to organelles in live neurons induces unidirectional transport in axons but bidirectional transport with a net retrograde bias in dendrites. Removal of the secondary microtubule-binding regions of KIF21B or dampening of microtubule dynamics with low concentrations of nocodazole eliminates retrograde bias in live dendrites. Further exploration of the contribution of microtubule dynamics in dendrites to directionality revealed plus end–out microtubules to be more dynamic than plus end–in microtubules, with nocodazole preferentially stabilizing the plus end–out population. We propose a model in which both nucleotide-sensitive and -insensitive microtubule-binding sites of KIF21B motors contribute to the search and selection of stable plus end–in microtubules within the mixed polarity microtubule arrays characteristic of mammalian dendrites to achieve net retrograde movement of KIF21B-bound cargoes.

Tracking the Amide I and αCOO- Terminal ν(C=O) Raman Bands in a Family of l-Glutamic Acid-Containing Peptide Fragments: A Raman and DFT Study

The E-hook of β-tubulin plays instrumental roles in cytoskeletal regulation and function. The last six C-terminal residues of the βII isotype, a peptide of amino acid sequence EGEDEA, extend from the microtubule surface and have eluded characterization with classic X-ray crystallographic techniques. The band position of the characteristic amide I vibration of small peptide fragments is heavily dependent on the length of the peptide chain, the extent of intramolecular hydrogen bonding, and the overall polarity of the fragment. The dependence of the E residue's amide I ν(C=O) and the αCOO- terminal ν(C=O) bands on the neighboring side chain, the length of the peptide fragment, and the extent of intramolecular hydrogen bonding in the structure are investigated here via the EGEDEA peptide. The hexapeptide is broken down into fragments increasing in size from dipeptides to hexapeptides, including EG, ED, EA, EGE, EDE, DEA, EGED, EDEA, EGEDE, GEDEA, and, finally, EGEDEA, which are investigated with experimental Raman spectroscopy and density functional theory (DFT) computations to model the zwitterionic crystalline solids (in vacuo). The molecular geometries and Boltzmann sum of the simulated Raman spectra for a set of energetic minima corresponding to each peptide fragment are computed with full geometry optimizations and corresponding harmonic vibrational frequency computations at the B3LYP/6-311++G(2df,2pd) level of theory. In absence of the crystal structure, geometry sampling is performed to approximate solid phase behavior. Natural bond order (NBO) analyses are performed on each energetic minimum to quantify the magnitude of the intramolecular hydrogen bonds. The extent of the intramolecular charge transfer is dependent on the overall polarity of the fragment considered, with larger and more polar fragments exhibiting the greatest extent of intramolecular charge transfer. A steady blue shift arises when considering the amide I band position moving linearly from ED to EDE to EDEA to GEDEA and, finally, to EGEDEA. However, little variation is observed in the αCOO- ν(C=O) band position in this family of fragments.

Multifaceted effect of chlorpromazine in cancer: implications for cancer treatment

Since its discovery in 1951, chlorpromazine (CPZ) has been one of the most widely used antipsychotic medications for treating schizophrenia and other psychiatric disorders. In addition to its antipsychotic effect, many studies in the last several decades have found that CPZ has a potent antitumorigenic effect. These studies have shown that CPZ affects a number of molecular oncogenic targets through multiple pathways, including the regulation of cell cycle, cancer growth and metastasis, chemo-resistance and stemness of cancer cells. Here we review studies on molecular mechanisms of CPZ’s action on key proteins involved in cancer, including p53, YAP, Ras protein, ion channels, and MAPKs. We discuss common and overlapping signaling pathways of CPZ’s action, its cancer-type specificity, antitumorigenic effects of CPZ reported in animal models and population studies on the rate of cancer in psychiatric patients. We also discuss the potential benefits and limitations of repurposing CPZ for cancer treatment.

Rethinking temperature effects on leaf growth, gene expression and metabolism: Diel variation matters

Plants have evolved to grow under prominently fluctuating environmental conditions. In experiments under controlled conditions, temperature is often set to artificial, binary regimes with constant values at day and at night. This study investigated how such a diel (24 hr) temperature regime affects leaf growth, carbohydrate metabolism and gene expression, compared to a temperature regime with a field-like gradual increase and decline throughout 24 hr. Soybean (Glycine max) was grown under two contrasting diel temperature treatments. Leaf growth was measured in high temporal resolution. Periodical measurements were performed of carbohydrate concentrations, carbon isotopes as well as the transcriptome by RNA sequencing. Leaf growth activity peaked at different times under the two treatments, which cannot be explained intuitively. Under field-like temperature conditions, leaf growth followed temperature and peaked in the afternoon, whereas in the binary temperature regime, growth increased at night and decreased during daytime. Differential gene expression data suggest that a synchronization of cell division activity seems to be evoked in the binary temperature regime. Overall, the results show that the coordination of a wide range of metabolic processes is markedly affected by the diel variation of temperature, which emphasizes the importance of realistic environmental settings in controlled condition experiments.

Modeling reveals cortical dynein-dependent fluctuations in bipolar spindle length

Proper formation and maintenance of the mitotic spindle is required for faithful cell division. Although much work has been done to understand the roles of the key molecular components of the mitotic spindle, identifying the consequences of force perturbations in the spindle remains a challenge. We develop a computational framework accounting for the minimal force requirements of mitotic progression. To reflect early spindle formation, we model microtubule dynamics and interactions with major force-generating motors, excluding chromosome interactions that dominate later in mitosis. We directly integrate our experimental data to define and validate the model. We then use simulations to analyze individual force components over time and their relationship to spindle dynamics, making it distinct from previously published models. We show through both model predictions and biological manipulation that rather than achieving and maintaining a constant bipolar spindle length, fluctuations in pole-to-pole distance occur that coincide with microtubule binding and force generation by cortical dynein. Our model further predicts that high dynein activity is required for spindle bipolarity when kinesin-14 (HSET) activity is also high. To the best of our knowledge, our results provide novel insight into the role of cortical dynein in the regulation of spindle bipolarity.

Gene expression of cytokinesis regulators PRC1, KIF14 and CIT has no prognostic role in colorectal and pancreatic cancer

Colorectal cancer is one of the most common cancers and pancreatic cancer is among the most fatal and difficult to treat. New prognostic biomarkers are urgently needed to improve the treatment of colorectal and pancreatic cancer. Protein regulating cytokinesis 1 (PRC1), kinesin family member 14 (KIF14) and citron Rho-interacting serine/threonine kinase (CIT) serve important roles in cytokinesis, are strongly associated with cancer progression and have prognostic potential. The present study aimed to investigate the prognostic relevance of the PRC1, KIF14 and CIT genes in colorectal and pancreatic cancer. PRC1, KIF14 and CIT transcript expression was assessed by reverse transcription-quantitative PCR in tumors and paired distant unaffected mucosa from 67 patients with colorectal cancer and tumors and paired non-neoplastic control tissues from 48 patients with pancreatic cancer. The extent of transcript dysregulation between tumor and control tissues and between groups of patients divided by main clinical characteristics, namely patients' age and sex, disease stage, localization and grade, was determined. Finally, the associations of transcript levels in tumors with disease-free interval and overall survival time were evaluated. PRC1, KIF14 and CIT transcripts were upregulated in tumors compared with control tissues. PRC1, KIF14 and CIT levels strongly correlated to each other in both colorectal and pancreatic tumor and control tissues after correction for multiple testing. However, no significant associations were found among the transcript levels of PRC1, KIF14 and CIT and disease-free interval or overall survival time. In summary, the present study demonstrated mutual correlation of PRC1, KIF14 and CIT cytokinesis regulators with no clear prognostic value in pancreatic and colorectal cancers. Hence, according to the results of the present study, transcript levels of these genes cannot be clinically exploited as prognostic biomarkers in colorectal or pancreatic cancer patients.

Measuring force generation within reconstituted microtubule bundle assemblies using optical tweezers

Kinesins and microtubule associated proteins (MAPs) are critical to sustain life, facilitating cargo transport, cell division, and motility. To interrogate the mechanistic underpinnings of their function, these microtubule-based motors and proteins have been studied extensively at the single molecule level. However, a long-standing issue in the single molecule biophysics field has been how to investigate motors and associated proteins within a physiologically relevant environment in vitro. While the one motor/one filament orientation of a traditional optical trapping assay has revolutionized our knowledge of motor protein mechanics, this reductionist geometry does not reflect the structural hierarchy in which many motors work within the cellular environment. Here, we review approaches that combine the precision of optical tweezers with reconstituted ensemble systems of microtubules, MAPs, and kinesins to understand how each of these unique elements work together to perform large scale cellular tasks, such as but not limited to building the mitotic spindle. Not only did these studies develop novel techniques for investigating motor proteins in vitro, but they also illuminate ensemble filament and motor synergy that helps bridge the mechanistic knowledge gap between previous single molecule and cell level studies.

The functions of kinesin and kinesin-related proteins in eukaryotes

Kinesins constitute a superfamily of ATP-driven microtubule motor enzymes that convert the chemical energy of ATP hydrolysis into mechanical work along microtubule tracks. Kinesins are found in all eukaryotic organisms and are essential to all eukaryotic cells, involved in diverse cellular functions such as microtubule dynamics and morphogenesis, chromosome segregation, spindle formation and elongation and transport of organelles. In this review, we explore recently reported functions of kinesins in eukaryotes and compare their specific cargoes in both plant and animal kingdoms to understand the possible roles of uncharacterized motors in a kingdom based on their reported functions in other kingdoms.

KIF15 is involved in development and progression of Burkitt lymphoma

BACKGROUND

Burkitt lymphoma (BL) is a highly aggressive, fast-growing B-cell non-Hodgkin's lymphoma, manifested in several subtypes, including sporadic, endemic, and immunodeficiency-related forms, the mechanism of which is still not clear. Abundant evidence reported that KIF15 was involved in the progression of human cancer. The emphasis of this study is to explore the functions of KIF15 in the development of BL.

METHODS

Firstly, tumor and normal tissues were collected for detecting expression of KIF15 in BL. Lentivirus-mediated shRNA knockdown of KIF15 was used to construct BL cell model, which was verified by qRT-PCR and Western Blot. The cell proliferation was detected by CCK8 assay, cell apoptosis and cell cycle were measured through flow cytometry. Transwell assay was conducted to detect the migration.

RESULTS

We first found that KIF15 is highly expressed in BL. Knockdown of KIF15 can inhibit proliferation and migration, promote apoptosis and arrest the cell cycle. Moreover, KIF15 is involved in BL cell activity through regulating expression of apoptosis-related proteins (Caspase3, Caspase8, HTRA, IGFBP-6, p53, SMAC, sTNF-R1, TNF-β and Bcl-2) and downstream pathways, such as p-Akt, CCND1, CDK6 and PIK3CA.

CONCLUSIONS

These findings justify the search for small molecule inhibitors targeting KIF15 as a novel therapeutic strategy in BL.

High KIF11 expression is associated with poor outcome of NSCLC

PURPOSE

To clarify the correlation between KIF11 (kinesin family member 11) and clinicopathologic characteristics of non-small cell lung cancer (NSCLC) and identify the prognostic value of KIF11 in patients with NSCLC.

METHODS

For investigating the expression of KIF11 in NSCLC, two tissue microarrays (TMAs: one contained 60 paired NSCLC tissues and paratumor tissues, the other contained 140 NSCLC tissues and 10 normal lung tissues) were constructed, stained, and scored. The Cancer Genome Atlas (TCGA) datasets were used to explore the differential expression level of KIF11 between NSCLC and paratumor. Kaplan-Meier survival curves were plotted and multivariate analysis were carried out.

RESULTS

The staining of KIF11 mainly distributed throughout the cytoplasm of tumor cells. Its expression was higher in NSCLC than paratumor cells, and similar results were obtained from TCGA datasets. We found that high expression of KIF11 had a significant correlation with lymph node metastases (p = 0.024) and pathologic stage (p = 0.018); that significant difference was not found in any other clinicopathologic characteristic. As univariate and multivariate analysis showed, KIF11 expression was significantly correlated with overall survival time of NSCLC (p = 0.002, p = 0.025, respectively). High KIF11 expression was found to significantly associate with overall survival of stage II-III (p = 0.001) and lung adenocarcinoma (p = 0.036).

CONCLUSION

High KIF11 expression predicts poor outcome in NSCLC. KIF11 is expected to be a viable prognostic biomarker for NSCLC.

Effect of KIF22 on promoting proliferation and migration of gastric cancer cells via MAPK-ERK pathways

Background

Gastric cancer (GC) is one of the most globally prevalent cancers in the world. The pathogenesis of GC has not been fully elucidated, and there still lacks effective targeted therapeutics. The influence of altered kinesin superfamily protein 22 (KIF22) expression in GC progression is still unclearly. The aim of this study was to investigate the KIF22 effects on GC and related mechanisms.

Methods

Gastric carcinoma tissues and matching non-cancerous tissues were collected from patients with GC who have accepted a radical gastrectomy in Lanzhou University Second Hospital from May 2013 to December 2014. The expression of KIF22 was examined in GC of 67 patients and 20 para-carcinoma tissues by immunochemical staining. The relationship between the expression of KIF22 and clinicopathologic characteristics was next investigated in the remaining 52 patients except for 15 patients who did not complete follow-up for 5 years. Cell viability was performed via 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) test and colony formation assay in the MGC-803 and BGC-823 GC cells. Cell scratch and trans-well invasion assay was performed to assess migration ability in the MGC-803 and BGC-823 GC cells. Gene set enrichment analysis (GSEA) pathway enrichment analysis was performed to explore the potential functions. Cell cycle was detected by flow cytometry. In addition, the two GC cell lines were used to elucidate the underlying mechanism of KIF22 in GC in vitro via assessing the effects on mitogen-activated protein kinase and extracellular regulated protein kinases (MAPK/ERK) signal transduction pathway-related expressions by Western blotting assays. The differences were compared by t tests, one-way analysis of variance, and Chi-squared tests.

Results

The study showed that KIF22 was up-regulated in GC, and KIF22 high expression was significantly related to differentiation degree (χ² = 12.842, P = 0.002) and poorly overall survivals. GSEA pathway enrichment analysis showed that KIF22 was correlated with the cell cycle. Silence of KIF22 decreased the ability of the proliferation and migration in gastric cells, induced G1/S phase cell cycle arrest via regulating the MAPK-ERK pathways.

Conclusions

KIF22 protein level was negatively correlated with prognosis. KIF22 knockdown might inhibit proliferation and metastasis of GC cells via the MAPK-ERK signaling pathway.

KIF21B Expression in Osteosarcoma and Its Regulatory Effect on Osteosarcoma Cell Proliferation and Apoptosis Through the PI3K/AKT Pathway

Osteosarcoma (OS) is the most common malignancy that occurs mainly during childhood and adolescence; however, no clear molecular or biological mechanism has been identified. In this study, we aimed to explore new biomarkers for the early diagnosis, targeted treatment, and prognostic determination of osteosarcoma. We first used bioinformatics analysis to show that KIF21B can be used as a biomarker for the diagnosis and prognosis of osteosarcoma. We then examined the expression of KIF21B in human osteosarcoma tissues and cell lines using immunohistochemistry, western blotting, and qRT-PCR. It was found that KIF21B expression was significantly upregulated in osteosarcoma tissues and cell lines. After knocking down the expression of KIF21B in the osteosarcoma cell lines 143B and U2-OS, we used cell fluorescence counting, CCK-8 assays, flow cytometry, and TUNEL staining to examine the effects of KIF21B on osteosarcoma cell proliferation and apoptosis. The results demonstrated that knocking down KIF21B in 143B and U2-OS cells could increase cell apoptosis, inhibit cell proliferation, and reduce tumor formation in nude mice. Subsequently, we used gene chips and bioinformatics to analyze the differential gene expression caused by knocking down KIF21B. The results showed that KIF21B may regulate OS cell proliferation and apoptosis by targeting the PI3K/AKT pathway. We then examined the expression of PI3K/AKT- and apoptosis-related proteins using western blotting. KIF21B knockdown inhibited the PI3K pathway, downregulated Bcl-2, and upregulated Bax. Moreover, the use of PI3K/AKT pathway agonists reversed the regulatory effect of KIF21B on the apoptosis and proliferation of 143B and U2-OS cells. In conclusion, our results indicated that KIF21B plays a key role in osteosarcoma. Low KIF21B expression might indirectly increase the apoptosis and inhibit the proliferation of osteosarcoma cells through the PI3K/AKT pathway.

Upregulation of KIF11 in TP53 Mutant Glioma Promotes Tumor Stemness and Drug Resistance

Glioma is the most common type of primary brain malignancy with high morbidity and mortality, but little is known about its pathological mechanisms. Kinesin family member 11 (KIF11) is a key driver of malignancy in glioblastoma, a grade IV glioma, but its involvement in glioma chemoresistance remains to be determined. We accessed the TCGA open datasets, collected glioma tumor tissue samples, and analyzed the expression of KIF11 in glioma patients. Meanwhile, the correlation between KIF11 and survival outcomes was determined by the Kaplan-Meier analysis. The role of KIF11 in glioma tumor cell function was assessed in an in vitro knockdown and overexpressing system. Here, we found that KIF11 was upregulated in glioma tumors and negatively correlated with overall survival outcomes via analyzing the open datasets. KIF11 was negatively correlated with TP53 expression. Furthermore, KIF11 promoted the stemness in glioma cells, accompanied by increased cell proliferation and chemoresistance. Mechanistically, we found that KIF11 promoted cell cycle progression via upregulating cyclin expression.

Determination of vibrational band positions in the E-hook of β-tubulin

Raman spectral characterization of the β-TUBB2A E-hook hexapeptide, EGEDEA, is determined through experimental analysis combined with full geometry optimizations and corresponding harmonic vibrational frequency computations employing DFT methods. The hexapeptide is first broken down into di- and tetrapeptide fragments which are analyzed both quantum chemically and experimentally, and then combined to achieve an energetic minimum of the large EGEDEA hexapeptide. The Raman spectral characterization of EGEDEA band positions are then verified via the literature and comparison to the small fragment's similarly located band positions. The approach employed provides further evidence for the use of fragments as a helpful tool in characterization of the vibrational band positions of large peptides. STATEMENT OF SIGNIFICANCE: To investigate β-TUBB2A E-hook hexapeptide, a unique approach is employed whereby the hexapeptide is broken into fragments, EG, ED, EA, EGED, and EDEA and analyzed via experimental Raman spectroscopy of the crystalline solids. The experimentally observed vibrational band positions are compared to those computed using and scaled from DFT methods and Pople's 6-311+G(2df,2pd) basis set. The reported vibrational band positions are also confirmed by previously reported bands of similar peptides in the literature. This methodology facilitates differentiation between the behaviors of various side chains and their influence on the structure of the hexapeptide, providing insight into not only the nature of the peptide but also defining regions for potential protein and cytoplasmic interactions, without requiring excessive computing resources or overly-sensitive experimental methods.

KIF11 Promotes Proliferation of Hepatocellular Carcinoma among Patients with Liver Cancers

BACKGROUND

Hepatocellular carcinoma (HCC) lacks effective treatments and has a poor prognosis. Therefore it is needed to develop more effective drug targets. Kinesin family member 11 (KIF11) has been reported to affect the progression of several cancers, and its high expression associates with the prognosis of patients. However, the relevant mechanisms of KIF11 in HCC progression have not been studied.

METHOD

Through the cancer genome atlas (TCGA) database and immunohistochemical (IHC) staining of patients' specimens, we determined that KIF11 was highly expressed in HCC tissues and associated with prognosis. We established a KIF11 stably depleted hepatoma cell line, through cell-cloning experiments and cell counting kit-8 (CCK-8) assays to detect the effects on proliferation in vitro. The role of KIF11 in promoting cell proliferation was verified in mice.

RESULT

The expression of KIF11 was negatively correlated with the overall survival (OS) and disease-free survival (DFS) and positively correlated with tumor size of HCC patients. KIF11 depletion inhibits cell proliferation and tumor growth in vitro and in vivo. Conclusion. KIF11 can be used as a positive correlation marker for HCC prognosis and served as a potential therapeutic target.

Evaluating Phenyl Propanoids Isolated from Citrus medica as Potential Inhibitors for Mitotic kinesin Eg5

Background:

Human mitotic kinesins play an essential role in mitotic cell division. Targeting the spindle separation phase of mitosis has gained much attention in cancer chemotherapy. Spindle segregation is carried out mainly by the kinesin, Eg5. Many Eg5 inhibitors are in different phases of clinical trials as cancer drugs. This enzyme has two allosteric binding sites to which the inhibitors can bind. The first site is formed by loop L5, helix α2 and helix α3 and all the current drug candidates bind un-competitively to this site with ATP/ADP. The second site, formed by helix α4 and helix α6, which has gained attention recently, has not been explored well. Some inhibitors that bind to this site are competitive, while others are uncompetitive to ATP/ADP. Phenylpropanoids are pharmacologically active secondary metabolites.

Methods:

In this study, we have evaluated fourteen phenyl propanoids extracted from Citrus medica for inhibitory activity against human mitotic kinesin Eg5 in vitro steady-state ATPase assay. Ther interactions and stability using molecular docking and molecular dynamics simulations.

Results and Discussions:

Of the fourteen compounds tested, naringin and quercetin showed good activity with IC50 values in the micromolar range. Molecular docking studies of these complexes showed that both the molecules interact with the key residues of the active site predominantly thorough hydrophobic & aromatic π–π interactions consistent with the known inhibitors. Besides, these molecules also form hydrogen bonding interactions stabilizing the complexes. Molecular dynamics simulations of these complexes confirm the stability of these interactions.

Conclusion:

These results can be used as a strong basis for further modification of these compounds to design new inhibitors with higher potency using structure-based drug design.

Plasmodium berghei Kinesin-5 Associates With the Spindle Apparatus During Cell Division and Is Important for Efficient Production of Infectious Sporozoites

Kinesin-5 motors play essential roles in spindle apparatus assembly during cell division, by generating forces to establish and maintain the spindle bipolarity essential for proper chromosome segregation. Kinesin-5 is largely conserved structurally and functionally in model eukaryotes, but its role is unknown in the Plasmodium parasite, an evolutionarily divergent organism with several atypical features of both mitotic and meiotic cell division. We have investigated the function and subcellular location of kinesin-5 during cell division throughout the Plasmodium berghei life cycle. Deletion of kinesin-5 had little visible effect at any proliferative stage except sporozoite production in oocysts, resulting in a significant decrease in the number of motile sporozoites in mosquito salivary glands, which were able to infect a new vertebrate host. Live-cell imaging showed kinesin-5-GFP located on the spindle and at spindle poles during both atypical mitosis and meiosis. Fixed-cell immunofluorescence assays revealed kinesin-5 co-localized with α-tubulin and centrin-2 and a partial overlap with kinetochore marker NDC80 during early blood stage schizogony. Dual-color live-cell imaging showed that kinesin-5 is closely associated with NDC80 during male gametogony, but not with kinesin-8B, a marker of the basal body and axonemes of the forming flagella. Treatment of gametocytes with microtubule-specific inhibitors confirmed kinesin-5 association with nuclear spindles and not cytoplasmic axonemal microtubules. Altogether, our results demonstrate that kinesin-5 is associated with the spindle apparatus, expressed in proliferating parasite stages, and important for efficient production of infectious sporozoites.

Identification of KIF23 as a prognostic signature for ovarian cancer based on large-scale sampling and clinical validation

The purpose of this study is to explore the expression and clinical significance of KIF23 in ovarian cancer (OV) and identify potential targets for clinical treatment. Oncomine, GEO, and TCGA databases were used to analysis the expression of KIF23 in OV. The prognostic value of KIF23 gene was analyzed by the Kaplan-Meier plotter database. The molecular mechanism of KIF23 activity was analyzed from the perspective of immunology, gene mutation, copy number variation (CNV). Finally, immunohistochemistry was conducted to validate the expression of KIF23, univariable and multivariate cox analysis were used to determine its relationship with clinical characteristics and OV prognosis. It showed that highly expressed KIF23 is an adverse independent prognostic biomarker for OV patients. Genomics analysis showed that KIF23 expression was associated with mutations such as FLG2 and TTN, and was significantly enriched in DNA replication and the cell cycle tumor-related signaling pathways. Immunology analysis showed that KIF23 is closely related to the immune infiltration. KIF23 can not only performed as a prognosis signature in OV but also as a target of immune molecular therapeutics.

An interphase pool of KIF11 localizes at the basal bodies of primary cilia and a reduction in KIF11 expression alters cilia dynamics

KIF11 is a homotetrameric kinesin that peaks in protein expression during mitosis. It is a known mitotic regulator, and it is well-described that KIF11 is necessary for the formation and maintenance of the bipolar spindle. However, there has been a growing appreciation for non-mitotic roles for KIF11. KIF11 has been shown to function in such processes as axon growth and microtubule polymerization. We previously demonstrated that there is an interphase pool of KIF11 present in glioblastoma cancer stem cells that drives tumor cell invasion. Here, we identified a previously unknown association between KIF11 and primary cilia. We confirmed that KIF11 localized to the basal bodies of primary cilia in multiple cell types, including neoplastic and non-neoplastic cells. Further, we determined that KIF11 has a role in regulating cilia dynamics. Upon the reduction of KIF11 expression, the number of ciliated cells in asynchronously growing populations was significantly increased. We rescued this effect by the addition of exogenous KIF11. Lastly, we found that depleting KIF11 resulted in an increase in cilium length and an attenuation in the kinetics of cilia disassembly. These findings establish a previously unknown link between KIF11 and the dynamics of primary cilia and further support non-mitotic functions for this kinesin.

Inhibition of kinesin motor protein KIFC1 by AZ82 induces multipolar mitosis and apoptosis in prostate cancer cell

Kinesin 14 family member KIFC1 is a mitotic kinesin which contains a C-terminal motor domain and plays a vital role for clustering the amplified centrosomes. Overexpression of KIFC1 in prostate cancer (PCa) cells showed resistance to docetaxel (DTX). The present study revealed that small KIFC1 inhibitor AZ82 suppresed the transcription and translation of KIFC1 significantly in PCa cells. AZ82 inhibited the KIFC1 expression both in the cytoplasm and nucleus of PCa cells. Inhibition of KIFC1 by AZ82 caused multipolar mitosis in PCa cells via de-clustering the amplified centrosomes and decreased the rate of cancer cell growth and proliferation. Moreover, depletion of KIFC1 reduced cells entering the cell cycle and caused PCa cells death through apoptosis by increasing the expression of Bax and Cytochrome C. Thereby, KIFC1 silencing and inhibition decreased the PCa cells survival by inducing multipolar mitosis as well as apoptosis, suggesting inhibition of KIFC1 using AZ82 might be a strategy to treat PCa by controlling the cancer cell proliferation.

Nampt-mediated spindle sizing secures a post-anaphase increase in spindle speed required for extreme asymmetry

Meiotic divisions in oocytes are extremely asymmetric and require pre- and post-anaphase-onset phases of spindle migration. The latter induces membrane protrusion that is moulded around the spindle thereby reducing cytoplasmic loss. Here, we find that depleting the NAD biosynthetic enzyme, nicotinamide phosphoribosyl-transferase (Nampt), in mouse oocytes results in markedly longer spindles and compromises asymmetry. By analysing spindle speed in live oocytes, we identify a striking and transient acceleration after anaphase-onset that is severely blunted following Nampt-depletion. Slow-moving midzones of elongated spindles induce cortical furrowing deep within the oocyte before protrusions can form, altogether resulting in larger oocyte fragments being cleaved off. Additionally, we find that Nampt-depletion lowers NAD and ATP levels and that reducing NAD using small molecule Nampt inhibitors also compromises asymmetry. These data show that rapid midzone displacement is critical for extreme asymmetry by delaying furrowing to enable protrusions to form and link metabolic status to asymmetric division.

Meiotic cell division in oocytes is asymmetric and requires microtubule spindle migration after anaphase-onset. Here, the authors show that Nampt, an enzyme of the Nicotinamide adenine dinucleotide (NAD) biosynthetic pathway, contributes to post-anaphase spindle migration and oocyte division asymmetry by controlling spindle length.

KIF15 contributes to cell proliferation and migration in breast cancer

A number of kinesin proteins (KIFs) have been implicated in the development of multiple cancers. However, little is known about the expression and function of KIF15 in human breast cancer. Herein, we detected KIF15 expression in breast cancer tissues and paired adjacent normal tissues using immunohistochemistry and quantitative real-time polymerase chain reaction analysis, and the correlation of KIF15 expression with clinicopathological parameters was evaluated statistically. The role of KIF15 in cell proliferation, migration, tumor growth and metastasis of breast cancer cells was investigated in vitro and in vivo, and we explored potential molecular mechanisms underlying the effects of KIF15 in breast cancer through western blot analysis. The results revealed that increased KIF15 expression in breast cancer tissues were positively related with tumor size, lymph node metastasis and TNM stage, and higher KIF15 expression predicts a worse prognosis of patients with breast cancer. Furthermore, KIF15 knockdown markedly attenuated breast cancer cell proliferation, migration, tumor growth and metastasis in vitro and in vivo, and silenced KIF15 expression significantly inhibited the expression of phosphorylated AKT, phosphorylated JNK, and cyclin D1, while both p53 and p21 protein expressions were strongly enhanced. These results suggest that KIF15 is a potential oncogene in human breast cancer.

Why are ATP-driven microtubule minus-end directed motors critical to plants? An overview of plant multifunctional kinesins

In plants, microtubule and actin cytoskeletons are involved in key processes including cell division, cell expansion, growth and development, biotic and abiotic stress, tropisms, hormonal signalling as well as cytoplasmic streaming in growing pollen tubes. Kinesin enzymes have a highly conserved motor domain for binding microtubule cytoskeleton assisting these motors to organise their own tracks, the microtubules by using chemical energy of ATP hydrolysis. In addition to this conserved binding site, kinesins possess non-conserved variable domains mediating structural and functional interaction of microtubules with other cell structures to perform various cellular jobs such as chromosome segregation, spindle formation and elongation, transport of organelles as well as microtubules-actins cross linking and microtubules sliding. Therefore, how the non-motor variable regions specify the kinesin function is of fundamental importance for all eukaryotic cells. Kinesins are classified into ~17 known families and some ungrouped orphans, of which ~13 families have been recognised in plants. Kinesin-14 family consisted of plant specific microtubules minus end-directed motors, are much diverse and unique to plants in the sense that they substitute the functions of animal dynein. In this review, we explore the functions of plant kinesins, especially from non-motor domains viewpoint, focussing mainly on recent work on the origin and functional diversity of motors that drive microtubule minus-end trafficking events.

KIF11 and KIF15 mitotic kinesins are potential therapeutic vulnerabilities for malignant peripheral nerve sheath tumors

Background

Malignant peripheral nerve sheath tumor (MPNST) constitutes the leading cause of neurofibromatosis type 1–related mortality. MPNSTs contain highly rearranged hyperploid genomes and exhibit a high division rate and aggressiveness. We have studied in vitro whether the mitotic kinesins KIF11, KIF15, and KIF23 have a functional role in maintaining MPNST cell survival and can represent potential therapeutic vulnerabilities.

Methods

We studied the expression of kinesin mRNAs and proteins in tumors and cell lines and used several in vitro functional assays to analyze the impact of kinesin genetic suppression (KIF15, KIF23) and drug inhibition (KIF11) in MPNST cells. We also performed in vitro combined treatments targeting KIF11 together with other described MPNST targets.

Results

The studied kinesins were overexpressed in MPNST samples. KIF15 and KIF23 were required for the survival of MPNST cell lines, which were also more sensitive than benign control fibroblasts to the KIF11 inhibitors ispinesib and ARRY-520. Co-targeting KIF11 and BRD4 with ARRY-520 and JQ1 reduced MPNST cell viability, synergistically killing a much higher proportion of MPNST cells than control fibroblasts. In addition, genetic suppression of KIF15 conferred an increased sensitivity to KIF11 inhibitors alone or in combination with JQ1.

Conclusions

The mitotic spindle kinesins KIF11 and KIF15 and the cytokinetic kinesin KIF23 play a clear role in maintaining MPNST cell survival and may represent potential therapeutic vulnerabilities. Although further in vivo evidences are still mandatory, we propose a simultaneous suppression of KIF11, KIF15, and BRD4 as a potential therapy for MPNSTs.