Kinesins and cancer

CRISPR therapeutic tools for complex genetic disorders and cancer (Review)

One of the fundamental discoveries in the field of biology is the ability to modulate the genome and to monitor the functional outputs derived from genomic alterations. In order to unravel new therapeutic options, scientists had initially focused on inducing genetic alterations in primary cells, in established cancer cell lines and mouse models using either RNA interference or cDNA overexpression or various programmable nucleases [zinc finger nucleases (ZNF), transcription activator-like effector nucleases (TALEN)]. Even though a huge volume of data was produced, its use was neither cheap nor accurate. Therefore, the clustered regularly interspaced short palindromic repeats (CRISPR) system was evidenced to be the next step in genome engineering tools. CRISPR-associated protein 9 (Cas9)-mediated genetic perturbation is simple, precise and highly efficient, empowering researchers to apply this method to immortalized cancerous cell lines, primary cells derived from mouse and human origins, xenografts, induced pluripotent stem cells, organoid cultures, as well as the generation of genetically engineered animal models. In this review, we assess the development of the CRISPR system and its therapeutic applications to a wide range of complex diseases (particularly distinct tumors), aiming at personalized therapy. Special emphasis is given to organoids and CRISPR screens in the design of innovative therapeutic approaches. Overall, the CRISPR system is regarded as an eminent genome engineering tool in therapeutics. We envision a new era in cancer biology during which the CRISPR-based genome engineering toolbox will serve as the fundamental conduit between the bench and the bedside; nonetheless, certain obstacles need to be addressed, such as the eradication of side-effects, maximization of efficiency, the assurance of delivery and the elimination of immunogenicity.

Microtubules and Microtubule-Associated Proteins

Microtubules act as "railways" for motor-driven intracellular transport, interact with accessory proteins to assemble into larger structures such as the mitotic spindle, and provide an organizational framework to the rest of the cell. Key to these functions is the fact that microtubules are "dynamic." As with actin, the polymer dynamics are driven by nucleotide hydrolysis and influenced by a host of specialized regulatory proteins, including microtubule-associated proteins. However, microtubule turnover involves a surprising behavior-termed dynamic instability-in which individual polymers switch stochastically between growth and depolymerization. Dynamic instability allows microtubules to explore intracellular space and remodel in response to intracellular and extracellular cues. Here, we review how such instability is central to the assembly of many microtubule-based structures and to the robust functioning of the microtubule cytoskeleton.

Eg5 orchestrates porcine oocyte maturational progression by maintaining meiotic organelle arrangement

Background

Kinesin superfamily proteins are microtubule-based molecular motors essential for the intracellular transport of various cargos, including organelles, proteins, and RNAs. However, their exact roles during mammalian oocyte meiosis have not been fully clarified.

Results

Herein, we investigated the critical events during porcine oocyte meiotic maturation with the treatment of Eg5-specific inhibitor monastrol. We found that Eg5 inhibition resulted in oocyte meiotic failure by displaying the poor expansion of cumulus cells and reduced rate of polar body extrusion. In the meantime, the spindle assembly and chromosome alignment were compromised, accompanied by the decreased level of acetylated α-tubulin, indicative of less stable microtubules. Impaired actin dynamics and mitochondria integrity were also observed in Eg5-inhibited oocytes. Additionally, inhibition of Eg5 caused the abnormal distribution of cortical granules and ovastacin, a cortical granule component, potentially leading to the fertilization failure.

Conclusions

Our findings reveal that Eg5 possesses an important function in porcine oocyte meiotic progression by regulating the organelle dynamics and arrangement.

Kif15 functions as an active mechanical ratchet

Kif15 is a kinesin-12 that contributes critically to bipolar spindle assembly in humans. Here we use force-ramp experiments in an optical trap to probe the mechanics of single Kif15 molecules under hindering or assisting loads and in a variety of nucleotide states. While unloaded Kif15 is established to be highly processive, we find that under hindering loads, Kif15 takes <∼10 steps. As hindering load is increased, Kif15 forestep:backstep ratio decreases exponentially, with stall occurring at 6 pN. In contrast, under assisting loads, Kif15 detaches readily and rapidly, even from its AMPPNP state. Kif15 mechanics thus depend markedly on the loading direction. Kif15 interacts with a binding partner, Tpx2, and we show that Tpx2 locks Kif15 to microtubules under both hindering and assisting loads. Overall, our data predict that Kif15 in the central spindle will act as a mechanical ratchet, supporting spindle extension but resisting spindle compression.

Comparison of Cell Arrays and Multi-Well Plates in Microscopy-Based Screening

Multi-well plates and cell arrays enable microscopy-based screening assays in which many samples can be analysed in parallel. Each of the formats possesses its own strengths and weaknesses, but reference comparisons between these platforms and their application rationale is lacking. We aim to fill this gap by comparing two RNA interference (RNAi)-mediated fluorescence microscopy-based assays, namely epidermal growth factor (EGF) internalization and cell cycle progression, on both platforms. Quantitative analysis revealed that both platforms enabled the generation of data with the appearance of the expected phenotypes significantly distinct from the negative controls. The measurements of cell cycle progression were less variable in multi-well plates. The result can largely be attributed to higher cell numbers resulting in less data variability when dealing with the assay generating phenotypic cell subpopulations. The EGF internalization assay with a uniform phenotype over nearly the whole cell population performed better on cell arrays than in multi-well plates. The result was achieved by scoring five times less cells on cell arrays than in multi-well plates, indicating the efficiency of the cell array format. Our data indicate that the choice of the screening platform primarily depends on the type of the cellular assay to achieve a maximum data quality and screen efficiency.

KIF15 nanomechanics and kinesin inhibitors, with implications for cancer chemotherapeutics

Eg5, a mitotic kinesin, has been a target for anticancer drug development. Clinical trials of small-molecule inhibitors of Eg5 have been stymied by the development of resistance, attributable to mitotic rescue by a different endogenous kinesin, KIF15. Compared with Eg5, relatively little is known about the properties of the KIF15 motor. Here, we employed single-molecule optical-trapping techniques to define the KIF15 mechanochemical cycle. We also studied the inhibitory effects of KIF15-IN-1, an uncharacterized, commercially available, small-molecule inhibitor, on KIF15 motility. To explore the complementary behaviors of KIF15 and Eg5, we also scored the effects of small-molecule inhibitors on admixtures of both motors, using both a microtubule (MT)-gliding assay and an assay for cancer cell viability. We found that (i) KIF15 motility differs significantly from Eg5; (ii) KIF15-IN-1 is a potent inhibitor of KIF15 motility; (iii) MT gliding powered by KIF15 and Eg5 only ceases when both motors are inhibited; and (iv) pairing KIF15-IN-1 with Eg5 inhibitors synergistically reduces cancer cell growth. Taken together, our results lend support to the notion that a combination drug therapy employing both inhibitors may be a viable strategy for overcoming chemotherapeutic resistance.

Clinically Applicable Inhibitors Impacting Genome Stability

Advances in technology have facilitated the molecular profiling (genomic and transcriptomic) of tumours, and has led to improved stratification of patients and the individualisation of treatment regimes. To fully realize the potential of truly personalised treatment options, we need targeted therapies that precisely disrupt the compensatory pathways identified by profiling which allow tumours to survive or gain resistance to treatments. Here, we discuss recent advances in novel therapies that impact the genome (chromosomes and chromatin), pathways targeted and the stage of the pathways targeted. The current state of research will be discussed, with a focus on compounds that have advanced into trials (clinical and pre-clinical). We will discuss inhibitors of specific DNA damage responses and other genome stability pathways, including those in development, which are likely to synergistically combine with current therapeutic options. Tumour profiling data, combined with the knowledge of new treatments that affect the regulation of essential tumour signalling pathways, is revealing fundamental insights into cancer progression and resistance mechanisms. This is the forefront of the next evolution of advanced oncology medicine that will ultimately lead to improved survival and may, one day, result in many cancers becoming chronic conditions, rather than fatal diseases.

Advances in the Study of Aptamer-Protein Target Identification Using the Chromatographic Approach

Ever since the development of the process known as the systematic evolution of ligands by exponential enrichment (SELEX), aptamers have been widely used in a variety of studies, including the exploration of new diagnostic tools and the discovery of new treatment methods. Aptamers' ability to bind to proteins with high affinity and specificity, often compared to that of antibodies, enables the search for potential cancer biomarkers and helps us understand the mechanisms of carcinogenesis. The blind spot of those investigations is usually the difficulty in the selective extraction of targets attached to the aptamer. There are many studies describing the cell SELEX for the prime choice of aptamers toward living cancer cells or even whole tumors in the animal models. However, a dilemma arises when a large number of proteins are being identified as potential targets, which is often the case. In this article, we present a new analytical approach designed to selectively target proteins bound to aptamers. During studies, we have focused on the unambiguous identification of the molecular targets of aptamers characterized by high specificity to the prostate cancer cells. We have compared four assay approaches using electrophoretic and chromatographic methods for "fishing out" aptamer protein targets followed by mass spectrometry identification. We have established a new methodology, based on the fluorescent-tagged oligonucleotides commonly used for flow-cytometry experiments or as optic aptasensors, that allowed the detection of specific aptamer-protein interactions by mass spectrometry. The use of atto488-labeled aptamers for the tracking of the formation of specific aptamer-target complexes provides the possibility of studying putative protein counterparts without needing to apply enrichment techniques. Significantly, changes in the hydrophobic properties of atto488-labeled aptamer-protein complexes facilitate their separation by reverse-phase chromatography combined with fluorescence detection followed by mass-spectrometry-based protein identification. These comparative results of several methodological approaches confirmed the universal applicability of this method to studying aptamer-protein interactions with high sensitivity, showing superior properties compared with pull-down techniques.

Reducing protein regulator of cytokinesis 1 as a prospective therapy for hepatocellular carcinoma

Proteins that bind to microtubule are important for cell cycle, and some of these proteins show oncogenic characteristics with mechanisms not fully understood. Herein we demonstrate overexpression of protein regulator of cytokinesis 1 (PRC1), a microtubule-associated regulator of mitosis, in human hepatocellular carcinoma (HCC). Moreover, upregulated PRC1 is associated with lower survival rates of HCC patients. Mechanistically, reducing PRC1 blocks mitotic exit of HCC cells at telophase in a spindle assembly checkpoint independent manner, and acts synergistically with microtubule-associated agents (MTAs) to suppress p53-wt or p53-null HCC cells in a p53- or p14ARF-dependent manner; while overexpressing PRC1 increases the resistance of HCC to taxol. A combined treatment of taxol/shPRC1 results in 90% suppression of tumor growth in subcutaneous HCC xenograft models. In orthotopic xenograft mice, reducing PRC1 significantly alleviates HCC development and hepatic injury. Together, our results suggest a dual-mitotic suppression approach against HCC by combining MTAs with cytokinesis inhibition, which blocks mitosis at both metaphase and telophase.

Deregulation of the spindle assembly checkpoint is associated with paclitaxel resistance in ovarian cancer

Background

Ovarian cancer is the leading gynecologic cancer diagnosed in North America and because related symptoms are not disease specific, this often leads to late detection, an advanced disease state, and the need for chemotherapy. Ovarian cancer is frequently sensitive to chemotherapy at diagnosis but rapid development of drug resistance leads to disease progression and ultimately death in the majority of patients.

Results

We have generated paclitaxel resistant ovarian cell lines from their corresponding native cell lines to determine driver mechanisms of drug resistance using gene expression arrays. These paclitaxel resistant ovarian cells demonstrate: (1) Increased IC₅₀ for paclitaxel and docetaxel (10 to 75-fold) and cross-resistance to anthracyclines (2) Reduced cell apoptosis in the presence of paclitaxel (3) Gene depletion involving mitotic regulators BUB1 mitotic checkpoint serine/threonine kinase, cyclin BI (CCNB1), centromere protein E (CENPE), and centromere protein F (CENPF), and (4) Functional data validating gene depletion among mitotic regulators.

Conclusions

We have generated model systems to explore drug resistance in ovarian cancer, which have revealed a key pathway related to the spindle assembly checkpoint underlying paclitaxel resistance in ovarian cell lines.

Electronic supplementary material

The online version of this article (10.1186/s13048-018-0399-7) contains supplementary material, which is available to authorized users.

Functional transcriptomic annotation and protein-protein interaction network analysis identify NEK2, BIRC5, and TOP2A as potential targets in obese patients with luminal A breast cancer

PURPOSE

Although obesity is a risk factor for breast cancer, little effort has been made in the identification of druggable molecular alterations in obese-breast cancer patients. Tumors are controlled by their surrounding microenvironment, in which the adipose tissue is a main component. In this work, we intended to describe molecular alterations at a transcriptomic and protein-protein interaction (PPI) level between obese and non-obese patients.

METHODS AND RESULTS

Gene expression data of 269 primary breast tumors were compared between normal-weight (BMI < 25, n = 130) and obese (IMC > 30, n = 139) patients. No significant differences were found for the global breast cancer population. However, within the luminal A subtype, upregulation of 81 genes was observed in the obese group (FC ≥ 1.4). Next, we explored the association of these genes with patient outcome, observing that 39 were linked with detrimental outcome. Their PPI map formed highly compact cluster and functional annotation analyses showed that cell cycle, cell proliferation, cell differentiation, and cellular response to extracellular stimuli were the more altered functions. Combined analyses of genes within the described functions are correlated with poor outcome. PPI network analyses for each function were to search for druggable opportunities. We identified 16 potentially druggable candidates. Among them, NEK2, BIRC5, and TOP2A were also found to be amplified in breast cancer, suggesting that they could act as strategic players in the obese-deregulated transcriptome.

CONCLUSION

In summary, our in silico analysis describes molecular alterations of luminal A tumors and proposes a druggable PPI network in obese patients with potential for translation to the clinical practice.

Increased KIF4A expression is a potential prognostic factor in prostate cancer

The kinesin super-family protein (KIF) 4A gene is reported to be overexpressed and associated with poor clinical prognosis in human cancers; however, its clinical significance in prostate cancer (PCa) has not been well studied. The present study performed dataset analyses and revealed that KIF4A expression was significantly increased in castration-resistant PCa patients. Additionally, KIF4A expression was significantly highly expressed in PCa tissues compared with non-cancerous tissues, particularly in advanced PCa pathological stages. Upregulated KIF4A mRNA expression in PCa tissues was significantly correlated with shorter overall survival and prostate-specific antigen failure. Furthermore, both univariate and multivariate analyses revealed that upregulated KIF4A may predict poor biochemical recurrence (BCR)-free survival. The data suggested that KIF4A may play a key role in PCa progression. Notably, increased KIF4A expression may potentially predict poor BCR-free survival in PCa patients.

Kinesin Motor Protein KIFC1 Is a Target Protein of miR-338-3p and Is Associated With Poor Prognosis and Progression of Renal Cell Carcinoma

KIFC1 (kinesin family member C1) plays a critical role in clustering of extra centrosomes in various cancer cells and thus could be considered as a promising therapeutic target. However, whether KIFC1 is involved in the procession of renal cell carcinoma (RCC) still remains unclear. In this study, we found that KIFC1 was upregulated in RCC tissues and is responsible for RCC tumorigenesis (p < 0.001). The high expression of KIFC1 correlates with aggressive clinicopathologic parameters. Kaplan–Meier analysis suggested that KIFC1 was associated with poor survival prognosis in RCC. Silencing KIFC1 dramatically resulted in inhibition of proliferation, delayed the cell cycle at G₂/M phase, and suppressed cell invasion and migration in vitro. The antiproliferative effect of KIFC1 silencing was also observed in xenografted tumors in vivo. miR-338-3p could directly bind to the 3′-untranslated region (3′-UTR) of KIFC1, and ectopic miR-338-3p expression mimicked the inhibitory functions of KIFC1 silencing on RCC cells through inactivation of the PI3K/AKT signaling pathway. Therefore, these results revealed that KIFC1 may be a novel biomarker and an effective therapeutic target for the treatment of RCC.

Aberrant KIF20A expression might independently predict poor overall survival and recurrence-free survival of hepatocellular carcinoma

Kinesin family member 20A (KIF20A) is an essential regulator of cytokinesis. In this study, by performing a retrospective study based on data from the Cancer Genome Atlas (TCGA)-Liver and Hepatocellular Carcinoma (LIHC) cohort, we tried to assess the independent prognostic value of KIF20A in terms of overall survival (OS) and recurrence-free survival (RFS). Results showed that normal liver tissues had very low KIF20A expression compared with normal tissues in other cohorts in TCGA. However, the primary HCC tissues (N = 371) had significantly elevated KIF20A expression than normal liver tissues (N = 50). Immunohistochemistry (IHC) data showed that normal hepatocytes had weak KIF20A staining. In comparison, some HCC tissues had medium and strong KIF20A expression, with nuclear-enhanced staining. By grouping patients with primary HCC (N = 365) into high and low KIF20A expression groups, we found that the high expression group had a substantially higher proportion of high-grade tumors (G3/G4) (34/65, 52.3% vs. 96/295, 32.5%, P = 0.0027), advanced tumors (stage III/IV) (28/61, 45.9% vs. 59/280, 21.1%, P < 0.0001) and death (44/67, 65.7% vs. 86/298, 28.9%, P < 0.0001) compared with the low expression group. Kaplan-Meier curves of OS and RFS indicated that high KIF20A expression was associated with worse survival outcomes. Subgroup analysis confirmed the associations in G1/G2, G3/G4 tumors and in early and advanced stages. Following univariate and multivariate analysis revealed that KIF20A expression was an independent prognostic indicator for poor OS (HR: 1.304, 95%CI: 1.157-1.469, P < 0.001) and RFS (HR: 1.144, 95%CI: 1.028-1.272, P < 0.001). Based on these findings, we infer that KIF20A was aberrantly expressed in HCC tissues and its expression might independently predict poor OS and RFS. © 2018 IUBMB Life, 70(4):328-335, 2018.

Aberrantly activated Gli2-KIF20A axis is crucial for growth of hepatocellular carcinoma and predicts poor prognosis

Glioma-associated oncogene 2 (Gli2), a primary transcriptional regulator of Hedgehog (Hh) signaling, is essential for hepatocellular carcinoma (HCC) growth and survival. However, the underlying molecular mechanism and crucial downstream targets of Gli2 in human HCC are not fully understood. Here, we report the identification of kinesin family member 20A (KIF20A) as a novel downstream target of Gli2, which is important for HCC proliferation and tumor growth. Inhibition of Hh signaling leads to a remarkable decrease of KIF20A expression in HCC cells, whereas overexpression of Gli2 elevates KIF20A expression by activating Forkhead Box M1 (FoxM1)-MMB complex-mediated transcription of this kinesin gene. Gli2-induced HCC cell growth requires enhanced expression of KIF20A, and knockdown of Gli2 or KIF20A represses the proliferation of HCC cells in vitro and in vivo. Correlated with these results, analyses of clinical HCC samples show that Gli2, FoxM1 and KIF20A are highly elevated in primary HCC samples and represent significant risk factors for HCC recurrence and survival. Conclusion: KIF20A is an important downstream target gene of Hh signaling. And, the Gli2-KIF20A axis is essential for the proliferation and growth of human HCC cells. Our study also suggests Gli2-KIF20A axis as a potential target for future therapeutic intervention and as an independent prognostic biomarker for HCC.

High KIF2A expression promotes proliferation, migration and predicts poor prognosis in lung adenocarcinoma

The Kinesin family member 2a (KIF2A), that belongs to the Kinesin-13 microtubule depolymerases, plays an important role in cancer cell proliferation, migration and apoptosis in various types of cancer such as gastric cancer, breast cancer, and squamous cell carcinoma of the oral tongue, but, its role and mechanism in lung adenocarcinoma (LUAD) is largely unknown. The present study reported that KIF2A was overexpressed in LUAD tissues as compared with adjacent normal tissues. KIF2A was closely correlated with TNM stage and lymph node metastasis (P < 0.01), whereas, no similar relationships between KIF2A and age, gender, smoking and differentiation. Multivariate analysis indicated that hyperexpression of KIF2A in LUAD was an independent risk factor for worse overall survival in LUAD patients (HR: 3.135, 95%CI: 1.331-7.112, p < 0.05). In vitro, KIF2A knockdown markedly reduced LUAD cell A549 migration and could regulate epithelial-mesenchymal transition. Furthermore, silencing KIF2A inhibited cell proliferation and induced apoptosis in lung adenocarcinoma(LUAD) cells. In conclusion, KIF2A may serve as a valuable prognostic indicator and promising therapeutic target of LUAD.

Target identification of small molecules using large-scale CRISPR-Cas mutagenesis scanning of essential genes

Unraveling the mechanism of action and molecular target of small molecules remains a major challenge in drug discovery. While many cancer drugs target genetic vulnerabilities, loss-of-function screens fail to identify essential genes in drug mechanism of action. Here, we report CRISPRres, a CRISPR-Cas-based genetic screening approach to rapidly derive and identify drug resistance mutations in essential genes. It exploits the local genetic variation created by CRISPR-Cas-induced non-homologous end-joining (NHEJ) repair to generate a wide variety of functional in-frame mutations. Using large sgRNA tiling libraries and known drug-target pairs, we validate it as a target identification approach. We apply CRISPRres to the anticancer agent KPT-9274 and identify nicotinamide phosphoribosyltransferase (NAMPT) as its main target. These results present a powerful and simple genetic approach to create many protein variants that, in combination with positive selection, can be applied to reveal the cellular target of small-molecule inhibitors.

Biallelic variants in KIF14 cause intellectual disability with microcephaly

Kinesin proteins are critical for various cellular functions such as intracellular transport and cell division, and many members of the family have been linked to monogenic disorders and cancer. We report eight individuals with intellectual disability and microcephaly from four unrelated families with parental consanguinity. In the affected individuals of each family, homozygosity for likely pathogenic variants in KIF14 were detected; two loss-of-function (p.Asn83Ilefs*3 and p.Ser1478fs), and two missense substitutions (p.Ser841Phe and p.Gly459Arg). KIF14 is a mitotic motor protein that is required for spindle localization of the mitotic citron rho-interacting kinase, CIT, also mutated in microcephaly. Our results demonstrate the involvement of KIF14 in development and reveal a wide phenotypic variability ranging from fetal lethality to moderate developmental delay and microcephaly.

Evolution of Cytogenetically Normal Acute Myeloid Leukemia During Therapy and Relapse: An Exome Sequencing Study of 50 Patients

Purpose: To study mechanisms of therapy resistance and disease progression, we analyzed the evolution of cytogenetically normal acute myeloid leukemia (CN-AML) based on somatic alterations.Experimental Design: We performed exome sequencing of matched diagnosis, remission, and relapse samples from 50 CN-AML patients treated with intensive chemotherapy. Mutation patterns were correlated with clinical parameters.Results: Evolutionary patterns correlated with clinical outcome. Gain of mutations was associated with late relapse. Alterations of epigenetic regulators were frequently gained at relapse with recurring alterations of KDM6A constituting a mechanism of cytarabine resistance. Low KDM6A expression correlated with adverse clinical outcome, particularly in male patients. At complete remission, persistent mutations representing preleukemic lesions were observed in 48% of patients. The persistence of DNMT3A mutations correlated with shorter time to relapse.Conclusions: Chemotherapy resistance might be acquired through gain of mutations. Insights into the evolution during therapy and disease progression lay the foundation for tailored approaches to treat or prevent relapse of CN-AML. Clin Cancer Res; 24(7); 1716-26. ©2018 AACR.

Eukaryotic elongation factor 2 kinase upregulates the expression of proteins implicated in cell migration and cancer cell metastasis

Eukaryotic elongation factor 2 kinase (eEF2K) negatively regulates the elongation phase of mRNA translation and hence protein synthesis. Increasing evidence indicates that eEF2K plays an important role in the survival and migration of cancer cells and in tumor progression. As demonstrated by two-dimensional wound-healing and three-dimensional transwell invasion assays, knocking down or inhibiting eEF2K in cancer cells impairs migration and invasion of cancer cells. Conversely, exogenous expression of eEF2K or knocking down eEF2 (the substrate of eEF2K) accelerates wound healing and invasion. Importantly, using LC-HDMS^E analysis, we identify 150 proteins whose expression is decreased and 73 proteins which are increased upon knocking down eEF2K in human lung carcinoma cells. Of interest, 34 downregulated proteins are integrins and other proteins implicated in cell migration, suggesting that inhibiting eEF2K may help prevent cancer cell mobility and metastasis. Interestingly, eEF2K promotes the association of integrin mRNAs with polysomes, providing a mechanism by which eEF2K may enhance their cellular levels. Consistent with this, genetic knock down or pharmacological inhibition of eEF2K reduces the protein expression levels of integrins. Notably, pharmacological or genetic inhibition of eEF2K almost completely blocked tumor growth and effectively prevented the spread of tumor cells in vivo. High levels of eEF2K expression were associated with invasive carcinoma and metastatic tumors. These data provide the evidence that eEF2K is a new potential therapeutic target for preventing tumor metastasis.

The microtubule-associated protein PRC1 is a potential therapeutic target for lung cancer

In this study, we investigated whether proteins that are involved in cytokinesis are potential targets for therapy of lung cancer. We find that the microtubule-associated protein PRC1 (protein required for cytokinesis 1), which plays a key role in organizing anti-parallel microtubule in the central spindle in cytokinesis, is overexpressed in lung cancer cell lines compared to normal cells. Increased expression of PRC1 is correlated with a poor prognosis of human lung adenocarcinoma patients. Lentiviral delivered, inducible RNAi of PRC1 demonstrated that proliferation of lung cancer cell lines strongly depends on PRC1. Significantly, we also show that PRC1 is required for tumorigenesis in vivo using a mouse model for non-small cell lung cancer driven by oncogenic K-RAS and loss of p53. When PRC1 is depleted by in vivo RNA interference, lung tumor formation is significantly reduced. Although PRC1 has been suggested to regulate Wnt/ß-catenin signaling in cancer cells, we find no evidence for a role of PRC1 in this pathway in lung cancer. Instead, we show that the depletion of PRC1 results in a strong increase in bi- and multinuclear cells due to defects in cytokinesis. This ultimately leads to apoptosis and senescence. Together these data establish PRC1 as a potential target for therapy of lung cancer.

PRC1: Linking Cytokinesis, Chromosomal Instability, and Cancer Evolution

Cytokinesis is the final event of the cell cycle dividing one cell into two daughter cells. The protein regulator of cytokinesis (PRC)1 is essential for cytokinesis and normal cell cleavage. Deregulation of PRC1 causes cytokinesis defects that promote chromosomal instability (CIN) and thus tumor heterogeneity and cancer evolution. Consistently, abnormal PRC1 expression correlates with poor patient outcome in various malignancies, which may be caused by PRC1-mediated CIN and aneuploidy. Here, we review the physiological functions of PRC1 in cell cycle regulation and its contribution to tumorigenesis and intratumoral heterogeneity. We discuss targeting PRC1 within the complementary approaches of either normalizing CIN in aneuploid cancers or creating chromosomal chaos in genomically stable cancers to induce apoptosis.

Immune microenvironment of experimental rat C6 gliomas resembles human glioblastomas

Glioblastoma (GBM) is the most aggressive primary brain tumor, with ineffective anti-tumor responses and a poor prognosis despite aggressive treatments. GBM immune microenvironment is heterogenous  and activation of specific immune populations in GBM is not fully characterized. Reliable animal models are critical for defining mechanisms of anti-tumor immunity. First we analyzed the immune subpopulations present in rat C6 gliomas. Using flow cytometry we determined kinetics of infiltration of myeloid cells and T lymphocytes into glioma-bearing brains. We found significant increases of the amoeboid, pro-tumorigenic microglia/macrophages, T helper (Th) and T regulatory (Treg) cells in tumor-bearing brains, and rare infiltrating T cytotoxic (Tc) cells. Transcriptomic analyses of glioma-bearing hemispheres revealed overexpression of invasion and immunosuppression-related genes, reflecting the immunosuppressive microenvironment. Microglia, sorted as CD11b⁺CD45^low cells from gliomas, displayed the pro-invasive and immunosuppressive type of activation. Accumulation of Th and Treg cells combined with the reduced presence of Tc lymphocytes in rat gliomas may result in the lack of effective anti–tumor responses. Transcriptional profiles of CD11b⁺ cells and composition of immune infiltrates in C6 gliomas indicate that rat C6 gliomas employ similar immune system evasion strategies as human GBMs.

KSP inhibitor SB743921 inhibits growth and induces apoptosis of breast cancer cells by regulating p53, Bcl-2, and DTL

Kinesin spindle protein (KSP) is a microtubule-associated motor protein that is specifically expressed by mitosis cells. It is highly expressed in various types of tumors including hematomalignances and solid tumors. Chemical KSP inhibition has become a novel strategy in the development of anticancer drugs. SB743921 is a selective inhibitor for KSP, which is a mitotic protein essential for cell-cycle progression. Although SB743921 has shown antitumor activities for several types of cancers and entered into clinical trials, its therapeutic effects on breast cancer and mechanisms have not been explored. In this study, we tested the antitumor activity of SB743921 in breast cancer cell lines and partly elucidated its mechanisms. KSP and denticleless E3 ubiquitin–protein ligase homolog (DTL) are overexpressed in breast cancer cells compared with no-cancer tissues. Chemical inhibition of KSP by SB743921 not only reduces proliferation but also induces cell-cycle arrest and leads to apoptosis in breast cancer cells. Treatment of MCF-7 and MDA-MB-231 breast cancer cell lines with SB743921 results in decreased ability of colony formation in culture. SB743921 treatment also causes a KSP accumulation in protein level that is associated with cell arrest. Furthermore, we showed that SB743921 treatment significantly reduces the expression of bcl-2 and cell cycle-related protein DTL, and upregulates p53 and caspase-3 in breast cancer cells. Taken together, these data indicated that SB743921 can be expected to be a novel treatment agent for breast cancers.

Structural basis of human kinesin-8 function and inhibition

Kinesins are a superfamily of ATP-dependent motors important for many microtubule-based functions, including multiple roles in mitosis. Small-molecule inhibitors of mitotic kinesins disrupt cell division and are being developed as antimitotic therapies. We investigated the molecular mechanism of the multitasking human mitotic kinesin Kif18A and its inhibition by the small molecule BTB-1. We used cryo-electron microscopy to visualize nucleotide-dependent conformational changes in microtubule-bound Kif18A, and the conformation of microtubule-bound, BTB-1-bound Kif18A. We calculated a putative BTB-1–binding site and validated this site experimentally to reveal the BTB-1 inhibition mechanism. Our work points to a general mechanism of kinesin inhibition, with wide implications for a targeted blockade of these motors in both dividing and interphase cells.

Kinesin motors play diverse roles in mitosis and are targets for antimitotic drugs. The clinical significance of these motors emphasizes the importance of understanding the molecular basis of their function. Equally important, investigations into the modes of inhibition of these motors provide crucial information about their molecular mechanisms. Kif18A regulates spindle microtubules through its dual functionality, with microtubule-based stepping and regulation of microtubule dynamics. We investigated the mechanism of Kif18A and its inhibition by the small molecule BTB-1. The Kif18A motor domain drives ATP-dependent plus-end microtubule gliding, and undergoes conformational changes consistent with canonical mechanisms of plus-end–directed motility. The Kif18A motor domain also depolymerizes microtubule plus and minus ends. BTB-1 inhibits both of these microtubule-based Kif18A activities. A reconstruction of BTB-1–bound, microtubule-bound Kif18A, in combination with computational modeling, identified an allosteric BTB-1–binding site near loop5, where it blocks the ATP-dependent conformational changes that we characterized. Strikingly, BTB-1 binding is close to that of well-characterized Kif11 inhibitors that block tight microtubule binding, whereas BTB-1 traps Kif18A on the microtubule. Our work highlights a general mechanism of kinesin inhibition in which small-molecule binding near loop5 prevents a range of conformational changes, blocking motor function.

A novel PHD-finger protein 14/KIF4A complex overexpressed in lung cancer is involved in cell mitosis regulation and tumorigenesis

The plant homeodomain (PHD) finger-containing proteins have been implicated in many human diseases including cancer. In this study, we found that PHF14, a newly identified PHD finger protein, is highly expressed in lung cancer. The high expression level of PHF14 was associated with adenocarcinoma and poor survival in lung cancer patients. Knocking down PHF14 suppressed cancer cell growth and carcinogenesis, while over-expressing PHF14 promoted cell proliferation. During cell division, PHF14 directly bound to and co-localized with KIF4A (a nuclear motor protein involved in lung carcinogenesis) to form a functional complex. Similarly to the effect of KIF4A depletion, silencing PHF14 in several cell lines caused cell mitotic defects, prolonged M phase, and inhibited cell proliferation. What's more, these two proteins had a synergistic effect on cell proliferation and were significantly co-overexpressed in lung cancer tissues. Our data provide new insights into the biological significance of PHD finger proteins and imply that PHF14 may be a potential biomarker for lung cancer.

Overexpression of KIFC1 and its association with spheroid formation in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most common human cancers. We previously reported that KIFC1 is involved in gastric cancer pathogenesis and that KIFC1 plays an important role in gastric cancer spheroid colony formation. However, the significance of KIFC1 in ESCC has not been examined. In the present study, we analyzed the expression and distribution of KIFC1 in 132 ESCC cases by immunohistochemistry. In contrast to weak or no staining of KIFC1 in non-neoplastic mucosa, ESCC tissue showed stronger, more extensive KIFC1 staining. In total, 95 (72%) of 132 ESCC cases were positive for KIFC1. Immunostaining of ALDH1 was also performed, and KIFC1-positive ESCC cases were significantly frequently found in ALDH1-positive ESCC cases compared with ALDH1-negative ESCC cases. Spheroid colony formation is an effective method to characterize CSCs, thus we analyzed sphere number and size at 15days in ESCC cells downregulated for KIFC1 by siRNA transfection. Both the number and size of sphere from TE-1 cells were significantly reduced in KIFC1 siRNA-transfected TE-1 cells than in negative control siRNA-transfected cells. These results suggest that KIFC1 plays an important role in ESCC pathogenesis.

KIF11 is required for proliferation and self-renewal of docetaxel resistant triple negative breast cancer cells

Development of chemoresistance remains a major hurdle for triple negative breast cancer treatment. Previous studies suggest that CD44+/CD24- cells, subpopulation of cancer stem cells with self-renewing and tumor-initiating capacities, are partly responsible for chemoresistance and therapeutic failure of triple negative breast cancer. Therefore, novel agents that target cancer stem cells (CSCs) may improve the clinical outcome. KIF11 (kinesin family member 11), overexpressed in many cancer cells, is a molecular motor protein that plays essential role in mitosis. In this study, we assess its role in docetaxel resistant triple negative breast cancer (TNBC). We found that the expression of KIF11 was significantly increased in CD44+/CD24- subpopulation of docetaxel resistant TNBC cells. Knockdown of KIF11 resulted in a significant decrease in the percentage of CSCs and mammosphere formation. KIF11 knockdown also inhibits cell growth and induces cell cycle G2/M arrest followed by cell mitosis and apoptosis. Further docetaxel resistant TNBC xenograft models demonstrated that KIF11 inhibitor exerts growth inhibitory effect in vivo. Of note, we also found that KIF11 was highly expressed in TNBC and its expression was correlated with shorter disease free survival time. All these data indicate that KIF11 is critical for proliferation and self-renewal in TNBC tumor cells in vitro and in vivo, suggesting that KIF11 may be a promising therapeutic target for treating chemoresistant TNBC.

Targeting mitotic pathways for endocrine-related cancer therapeutics

A colossal amount of basic research over the past few decades has provided unprecedented insights into the highly complex process of cell division. There is an ever-expanding catalog of proteins that orchestrate, participate and coordinate in the exquisite processes of spindle formation, chromosome dynamics and the formation and regulation of kinetochore microtubule attachments. Use of classical microtubule poisons has still been widely and often successfully used to combat a variety of cancers, but their non-selective interference in other crucial physiologic processes necessitate the identification of novel druggable components specific to the cell cycle/division pathway. Considering cell cycle deregulation, unscheduled proliferation, genomic instability and chromosomal instability as a hallmark of tumor cells, there lies an enormous untapped terrain that needs to be unearthed before a drug can pave its way from bench to bedside. This review attempts to systematically summarize the advances made in this context so far with an emphasis on endocrine-related cancers and the avenues for future progress to target mitotic mechanisms in an effort to combat these dreadful cancers.

Mitotic Vulnerability in Triple-Negative Breast Cancer Associated with LIN9 Is Targetable with BET Inhibitors

Triple-negative breast cancers (TNBC) are highly aggressive, lack FDA-approved targeted therapies, and frequently recur, making the discovery of novel therapeutic targets for this disease imperative. Our previous analysis of the molecular mechanisms of action of bromodomain and extraterminal protein inhibitors (BETi) in TNBC revealed these drugs cause multinucleation, indicating BET proteins are essential for efficient mitosis and cytokinesis. Here, using live cell imaging, we show that BET inhibition prolonged mitotic progression and induced mitotic cell death, both of which are indicative of mitotic catastrophe. Mechanistically, the mitosis regulator LIN9 was a direct target of BET proteins that mediated the effects of BET proteins on mitosis in TNBC. Although BETi have been proposed to function by dismantling super-enhancers (SE), the LIN9 gene lacks an SE but was amplified or overexpressed in the majority of TNBCs. In addition, its mRNA expression predicted poor outcome across breast cancer subtypes. Together, these results provide a mechanism for cancer selectivity of BETi that extends beyond modulation of SE-associated genes and suggest that cancers dependent upon LIN9 overexpression may be particularly vulnerable to BETi. Cancer Res; 77(19); 5395-408. ©2017 AACR.

The kinesin KIF14 is overexpressed in medulloblastoma and downregulation of KIF14 suppressed tumor proliferation and induced apoptosis

Medulloblastoma (MB) is the most common malignant brain tumor in childhood. At present, there is no well-established targeted drug for majority of patients. The kinesin family member 14 (KIF14) is a novel oncogene located on chromosome 1q and is dysregulated in multiple cancers. The objectives of this study were to evaluate KIF14 expression and chromosome 1q copy number in MB, and to delineate its biological functions in MB pathogenesis. By quantitative RT-PCR and immunohistochemistry, we found KIF14 was overexpressed in MB. Increased KIF14 expression at protein level was strongly associated with shorter progression-free survival (P=0.0063) and overall survival (P=0.0083). Fluorescence in situ hybridization (FISH) analysis confirmed genomic gain of chromosome 1q in 17/93 (18.3%) of MB. Combined genetic and immunohistochemical analyses revealed that 76.5% of MB with 1q gain showed consistent overexpression of KIF14, and a tight link between chromosome 1q gain and KIF14 overexpression (P=0.03). Transient, siRNAs-mediated downregulation of KIF14 suppressed cell proliferation and induced apoptosis in two MB cell lines. Stably KIF14 knockdown by shRNAs inhibited cell viability, colony formation, migration and invasion, and tumor sphere formation in MB cells. We conclude that KIF14 is dysregulated in MB and is an adverse prognostic factor for survival. Furthermore, KIF14 is part of MB biology and is a potential therapeutic target for MB.

Central spindle proteins and mitotic kinesins are direct transcriptional targets of MuvB, B-MYB and FOXM1 in breast cancer cell lines and are potential targets for therapy

The MuvB multiprotein complex, together with B-MYB and FOXM1 (MMB-FOXM1), plays an essential role in cell cycle progression by regulating the transcription of genes required for mitosis and cytokinesis. In many tumors, B-MYB and FOXM1 are overexpressed as part of the proliferation signature. However, the transcriptional targets that are important for oncogenesis have not been identified. Given that mitotic kinesins are highly expressed in cancer cells and that selected kinesins have been reported as target genes of MMB-FOXM1, we sought to determine which mitotic kinesins are directly regulated by MMB-FOXM1. We demonstrate that six mitotic kinesins and two microtubule-associated non-motor proteins (MAPs) CEP55 and PRC1 are direct transcriptional targets of MuvB, B-MYB and FOXM1 in breast cancer cells. Suppression of KIF23 and PRC1 strongly suppressed proliferation of MDA-MB-231 cells. The set of MMB-FOXM1 regulated kinesins genes and 4 additional kinesins which we referred to as the mitotic kinesin signature (MKS) is linked to poor outcome in breast cancer patients. Thus, mitotic kinesins could be used as prognostic biomarker and could be potential therapeutic targets for the treatment of breast cancer.

Regulation of paclitaxel activity by microtubule-associated proteins in cancer chemotherapy

Microtubules, highly dynamic components of the cytoskeleton, participate in diverse cellular activities such as mitosis, cell migration, and intracellular trafficking. Dysregulation of microtubule dynamics contributes to the development of serious diseases, including cancer. The dynamic properties and functions of microtubule network are regulated by microtubule-associated proteins. Paclitaxel, an anti-microtubule agent of the taxane family, has shown a success in clinical treatment of many cancer patients. However, the variable response activity of patients and acquired resistance to paclitaxel limit the clinical use of the drug. Accumulating studies show that microtubule-associated proteins can regulate paclitaxel sensitivity in a wide range of cancer types. In this review, we will describe the roles of various microtubule-associated proteins in the regulation of paclitaxel in cancers. Particularly, we will focus on the modulation of centrosomal proteins in paclitaxel resistance. Improved understandings of how these proteins act might predict treatment responses and provide insights into more rational chemotherapeutic regimens in clinical practice.

Upregulate KIF4A Enhances Proliferation, Invasion of Hepatocellular Carcinoma and Indicates poor prognosis Across Human Cancer Types

Hepatocellular carcinoma (HCC) is one of the most aggressive and heterogeneous cancers worldwide. Herein, we demonstrate KIF4A (Chromosome-associated kinesin KIF4A) as a potential biomarker, is up-regulated in most samples of HCC. The expression level of KIF4A in tumor tissue is significantly associated with the survival time, and a significant correlation between KIF4A expression and clinical information stage, metastasis and tumor dimension was observed. We further measured the proliferation and migration ability of two HCC cell lines, HCC-LM3 and PLC/PRF/5, following KIF4A-siRNA transfection. Knocking down of KIF4A significantly reduced migration and proliferation ability. Moreover, we also measured the proliferation and migration ability of two HCC cell lines through KIF4A overexpression, and found that KIF4A overexpression could enhance migration and proliferation ability, indicating that KIF4A exhibits oncogenic effects. Besides, study based on TCGA cohorts also reveals high KIF4A mRNA expression are significantly associated with shorter overall survival in multiple cancer types. Gene sets enrichment analysis exhibited that cell cycle related pathways and p53 signaling pathways to be top altered pathways of in KIF4A-high expression group in HCC, suggesting the potential role of KIF4A in mediating tumor initiation and progression. In summary, our work identified KIF4A as a potential predictive and prognostic marker for hepatocellular carcinoma.

Kinesin Processivity Is Determined by a Kinetic Race from a Vulnerable One-Head-Bound State

Kinesin processivity, defined as the average number of steps that occur per interaction with a microtubule, is an important biophysical determinant of the motor's intracellular capabilities. Despite its fundamental importance to the diversity of tasks that kinesins carry out in cells, no existing quantitative model fully explains how structural differences between kinesins alter kinetic rates in the ATPase cycle to produce functional changes in processivity. Here we use high-resolution single-molecule microscopy to directly observe the stepping behavior of kinesin-1 and -2 family motors with different length neck-linker domains. We characterize a one-head-bound posthydrolysis vulnerable state where a kinetic race occurs between attachment of the tethered head to its next binding site and detachment of the bound head from the microtubule. We find that greater processivity is correlated with faster attachment of the tethered head from this vulnerable state. In compliment, we show that slowing detachment from this vulnerable state by strengthening motor-microtubule electrostatic interactions also increases processivity. Furthermore, we provide evidence that attachment of the tethered head is irreversible, suggesting a first passage model for exit from the vulnerable state. Overall, our results provide a kinetic framework for explaining kinesin processivity and for mapping structural differences to functional differences in diverse kinesin isoforms.

KIF11 silencing and inhibition induces chromosome instability that may contribute to cancer

Understanding the aberrant pathways that contribute to oncogenesis and identifying the altered genes involved in these pathways is a critical first step to develop effective strategies to better combat cancer. Chromosome instability (CIN) is an aberrant phenotype that occurs in ∼80% of all cancer types and is associated with aggressive tumors, the acquisition of multidrug resistance and poor patient prognosis. Despite these associations however, the aberrant genes and molecular defects underlying CIN remain poorly understood. KIF11 is an evolutionarily conserved microtubule motor protein that functions in centrosome and chromosome dynamics in mitosis. Interestingly, the yeast ortholog of KIF11, namely CIN8 is a CIN gene and thus aberrant KIF11 expression and function is suspected to underlie CIN. In support of this possibility, KIF11 is somatically altered in a large number of cancer types. Using a complementary biochemical and genetic approach we examined whether KIF11 silencing with siRNAs or inhibition with monastrol was able to convert two distinct and karyotypically stable cell lines into karyotypically unstable cell lines. Indeed, quantitative imaging microscopy and flow cytometry revealed that KIF11 silencing induced increases in nuclear areas, micronucleus formation, DNA content and chromosome numbers relative to controls that was also observed following KIF11 inhibition. Collectively, this study identifies and validates KIF11 as an evolutionarily conserved CIN gene, and further suggests that aberrant expression and function may contribute to the pathogenesis of a subset of cancers.

Identification of altered pathways in breast cancer based on individualized pathway aberrance score

The objective of the present study was to identify altered pathways in breast cancer based on the individualized pathway aberrance score (iPAS) method combined with the normal reference (nRef). There were 4 steps to identify altered pathways using the iPAS method: Data preprocessing conducted by the robust multi-array average (RMA) algorithm; gene-level statistics based on average Z; pathway-level statistics according to iPAS; and a significance test dependent on 1 sample Wilcoxon test. The altered pathways were validated by calculating the changed percentage of each pathway in tumor samples and comparing them with pathways from differentially expressed genes (DEGs). A total of 688 altered pathways with P<0.01 were identified, including kinesin (KIF)- and polo-like kinase (PLK)-mediated events. When the percentage of change reached 50%, 310 pathways were involved in the total 688 altered pathways, which may validate the present results. In addition, there were 324 DEGs and 155 common genes between DEGs and pathway genes. DEGs and common genes were enriched in the same 9 significant terms, which also were members of altered pathways. The iPAS method was suitable for identifying altered pathways in breast cancer. Altered pathways (such as KIF and PLK mediated events) were important for understanding breast cancer mechanisms and for the future application of customized therapeutic decisions.

C-terminal kinesin motor KIFC1 participates in facilitating proper cell division of human seminoma

C-terminus kinesin motor KIFC1 is known for centrosome clustering in cancer cells with supernumerary centrosomes. KIFC1 crosslinks and glides on microtubules (MT) to assist normal bipolar spindle formation to avoid multi-polar cell division, which might be fatal. Testis cancer is the most common human cancer among young men. However, the gene expression profiles of testis cancer is still not complete and the expression of the C-terminus kinesin motor KIFC1 in testis cancer has not yet been examined. We found that KIFC1 is enriched in seminoma tissues in both mRNA level and protein level, and is specifically enriched in the cells that divide actively. Cell experiments showed that KIFC1 may be essential in cell division, but not essential in metastasis. Based on subcellular immuno-florescent staining results, we also described the localization of KIFC1 during cell cycle. By expressing ΔC-FLAG peptide in the cells, we found that the tail domain of KIFC1 might be essential for the dynamic disassociation of KIFC1, and the motor domain of KIFC1 might be essential for the degradation of KIFC1. Our work provides a new perspective for seminoma research.

Kif4A mediate the accumulation and reeducation of THP-1 derived macrophages via regulation of CCL2-CCR2 expression in crosstalking with OSCC

Crosstalk between tumor infiltrating macrophages and tumor cells is thought to play an indispensable role in oral squamous cell carcinomas (OSCC) by induction and maintenance of tolerance microenvironment. High infiltration of M2 macrophages and increasing expression of Kinesin family member 4A (Kif4A) in primary OSCC have been proved to correlate with greater tumoral size and poor clinical outcome. However, linkage between Kif4A and infiltrating macrophages in tumorigenesis and progression remains unclear. In the present study, we show that, the interaction between THP-1derived macrophage and OSCC cell line Cal-27 may up-regulate the Kif4A expression in both of them. Additionally, elevated soluble CCL2 in medium and more expression of CCR2 on macrophage were observed during the crosstalk. SiRNA of Kif4A and neutralizing antibody of CCL2 were utilized to identify that; increasing Kif4A can promote the recruitment of macrophages towards Cal-27 and educate them to M2 polarized macrophages via regulating CCL2/CCR2. In combination, the results of the present study may provide interesting clues to understanding the Kif4A-CCL2/CCR2-macrophage axis as a novel therapeutic target to improve the clinical outcome of OSCC.

Structural basis of cooperativity in kinesin revealed by 3D reconstruction of a two-head-bound state on microtubules

The detailed basis of walking by dimeric molecules of kinesin along microtubules has remained unclear, partly because available structural methods have been unable to capture microtubule-bound intermediates of this process. Utilizing novel electron cryomicroscopy methods, we solved structures of microtubule-attached, dimeric kinesin bound to an ATP analog. We find that under these conditions, the kinesin dimer can attach to the microtubule with either one or two motor domains, and we present sub-nanometer resolution reconstructions of both states. The former structure reveals a novel kinesin conformation that revises the current understanding of how ATP binding is coupled to forward stepping of the motor. The latter structure indicates how tension between the two motor domains keeps their cycles out of phase in order to stimulate directional motility. The methods presented here pave the way for future structural studies of a variety of challenging macromolecules that bind to microtubules and other filaments.

RNA-Seq based genome-wide analysis reveals loss of inter-chromosomal regulation in breast cancer

Breast cancer is a complex heterogeneous disease. Common hallmark features of cancer can be found. Their origin may be traced back to their intricate relationships governing regulatory programs during the development of this disease. To unveil distinctive features of the transcriptional regulation program in breast cancer, a pipeline for RNA-seq analysis in 780 breast cancer and 101 healthy breast samples, at gene expression and network level, was implemented. Inter-chromosomal relationships between genes resulted strikingly scarce in a cancer network, in comparison to its healthy counterpart. We suggest that inter-chromosomal regulation loss may be a novel feature in breast cancer. Additional evidence was obtained by independent validation in microarray and Hi-C data as well as supplementary computational analyses. Functional analysis showed upregulation in processes related to cell cycle and division; while migration, adhesion and cell-to-cell communication, were downregulated. Both the BRCA1 DNA repairing signalling and the Estrogen-mediated G1/S phase entry pathways were found upregulated. In addition, a synergistic underexpression of the γ-protocadherin complex, located at Chr5q31 is also shown. This region has previously been reported to be hypermethylated in breast cancer. These findings altogether provide further evidence for the central role of transcriptional regulatory programs in shaping malignant phenotypes.

KIF7 attenuates prostate tumor growth through LKB1-mediated AKT inhibition

This study investigated kinesin family member 7 (KIF7) expression and function in prostate cancer (PCa). Our results showed that KIF7 was significantly downregulated in PCa, compared with normal, benign prostatic hyperplasia and prostate intraepithelial neoplasia tissues, partially through promoter hypermethylation. We further investigated the effects of KIF7 coiled coil (CC) domain and motor domain (MD) on PCa development in vitro and in vivo. Our results showed that KIF7-CC but not KIF7-MD significantly attenuated proliferation and colony formation, impeded migration and invasion, induced apoptosis and sensitized PCa cells to paclitaxel. Further analysis revealed that KIF7-CC enhanced LKB1 expression and phosphorylation at Ser⁴²⁸, which induced PTEN phosphorylation at Ser³⁸⁰/Thr^382/383 and consequently blocked AKT phosphorylation at Ser⁴⁷³. Downregulation of LKB1 significantly attenuated the suppressive effects of KIF7-CC on cell proliferation, colony formation and AKT phosphorylation. Furthermore, our in vivo studies showed that KIF7-CC reduced prostate tumorigenesis in cell-derived xenografts. Downregulation of LKB1 abrogated the anti-tumor effects of KIF7-CC in these xenografts. Taken together, these findings provide the first evidence to support the role of KIF7 as a negative regulator that inhibits PCa development partially through LKB1-mediated AKT inhibition.

Eg5 Inhibitors Have Contrasting Effects on Microtubule Stability and Metaphase Spindle Integrity

To uncover their contrasting mechanisms, antimitotic drugs that inhibit Eg5 (kinesin-5) were analyzed in mixed-motor gliding assays of kinesin-1 and Eg5 motors in which Eg5 "braking" dominates motility. Loop-5 inhibitors (monastrol, STLC, ispinesib, and filanesib) increased gliding speeds, consistent with inducing a weak-binding state in Eg5, whereas BRD9876 slowed gliding, consistent with locking Eg5 in a rigor state. Biochemical and single-molecule assays demonstrated that BRD9876 acts as an ATP- and ADP-competitive inhibitor with 4 nM K_I. Consistent with its microtubule polymerase activity, Eg5 was shown to stabilize microtubules against depolymerization. This stabilization activity was eliminated in monastrol but was enhanced by BRD9876. Finally, in metaphase-arrested RPE-1 cells, STLC promoted spindle collapse, whereas BRD9876 did not. Thus, different Eg5 inhibitors impact spindle assembly and architecture through contrasting mechanisms, and rigor inhibitors may paradoxically have the capacity to stabilize microtubule arrays in cells.

Multicomponent Assembly of the Kinesin Spindle Protein Inhibitor CPUYJ039 and Analogues as Antimitotic Agents

The potent kinesin spindle protein inhibitor CPUYJ039 and a set of analogues were prepared by a target-oriented approach based on a Ugi reaction that uses 2-nitrophenyl isocyanides as key building blocks. The herein documented strategy provides straightforward and atom economical access to potent benzimidazole-based antimitotic agents by exploring the versatility and exploratory power of the Ugi reaction. The results of docking studies and biological activity evaluations of the benzimidazole compounds are also reported.

Identification of prognostic genes in kidney renal clear cell carcinoma by RNA‑seq data analysis

The present study aimed to analyze RNA-seq data of kidney renal clear cell carcinoma (KIRC) to identify prognostic genes. RNA‑seq data were downloaded from The Cancer Genome Atlas. Feature genes with a coefficient of variation (CV) >0.5 were selected using the genefilter package in R. Gene co‑expression networks were constructed with the WGCNA package. Cox regression analysis was performed using the survive package. Furthermore, a functional enrichment analysis was conducted using Database for Annotation, Visualization and Integrated Discovery tools. A total of 533 KIRC samples were collected, from which 6,758 feature genes with a CV >0.5 were obtained for further analysis. The KIRC samples were divided into two sets: The training set (n=319 samples) and the validation set (n=214 samples). Subsequently, gene co‑expression networks were constructed for the two sets. A total of 12 modules were identified, and the green module was significantly associated with survival time. Genes from the green module were revealed to be implicated in the cell cycle and p53 signaling pathway. In addition, a total of 11 hub genes were revealed, and 10 of them (CCNA2, CDC20, CDCA8, GTSE1, KIF23, KIF2C, KIF4A, MELK, TOP2A and TPX2) were validated as possessing prognostic value, as determined by conducting a survival analysis on another gene expression dataset. In conclusion, a total of 10 prognostic genes were identified in KIRC. These findings may help to advance the understanding of this disease, and may also provide potential biomarkers for therapeutic development.

Overexpression of Kinesin Family Member 20A Correlates with Disease Progression and Poor Prognosis in Human Nasopharyngeal Cancer: A Retrospective Analysis of 105 Patients

BACKGROUND

Numerous studies have shown Kinesin family member 20A (KIF20A) may play a critical role in the development and progression of cancer. However, the clinical value of KIF20A in nasopharyngeal carcinoma (NPC) is unknown. Here, we investigated the expression pattern of KIF20A in NPC and its correlation with clinicopathological features of patients.

METHODS

Real-time PCR and Western blotting were used to quantify KIF20A expression in NPC cell lines and clinical specimens compared with normal controls. KIF20A protein expression was also examined in archived paraffin embedded tumor samples from 105 patients with pathologically confirmed NPC by immunohistochemistry (IHC). Statistical analyses were applied to assess the associations between KIF20A expression and the clinicopathological features and survival outcomes. Effects on migration and invasion were assessed by wound healing and transwell invasion assays after KIF20A silencing.

RESULTS

KIF20A was significantly overexpressed at both the mRNA and protein levels in NPC cell lines and human tumor tissues. 45/105 (42.9%) of NPC specimens expressed high levels of KIF20A among the KIF20A detectable cases. Statistical analysis revealed that high KIF20A expression was significantly associated with gender (P = 0.046), clinical stage (P<0.001), T category (P = 0.022), N category (P<0.001), distant metastasis (P = 0.001) and vital status (P = 0.001). Moreover, Higher KIF20A expression patients had shorter overall survival (OS) and progression-free survival (PFS) (P = 0.001 and P = 0.001; log-rank test). In multivariate analysis, KIF20A was an independent prognostic factor for OS and PFS in the entire cohort (P = 0.033, P = 0.008). Knock down of KIF20A expression significantly suppressed NPC cell's migration and invasion.

CONCLUSIONS

KIF20A is overexpressed and may serve as an independent prognostic biomarker in NPC. Targeting KIF20A reduces migration and invasion of NPC cells.

Differentiated regulation of immune-response related genes between LUAD and LUSC subtypes of lung cancers

Lung squamous cell carcinoma (LUSC) and lung adenocarcinoma (LUAD) are the two major subtypes of lung cancer, with LUSC exhibits faster progression rate than LUAD. To investigate the roles of immune-response related genes (IRGs) in lung cancer progression, we used LUAD and LUSC samples at different cancer progression stages, and identified that the expression profiles of IRGs could serve as a better classification marker for cancerous tissues of both LUAD and LUSC. We found that the expression changes of IRGs were different between LUAD and LUSC. Cell cycle promoting genes, including KIFs and proteasomes, showed faster up-regulation in LUSC, whereas immune response promoting genes, including MHC molecules and chemokines, were more rapidly repressed in LUSC. Comparative pathway analysis revealed that members of the Toll-like receptor and T cell receptor signaling pathways exhibited diverged expression changes between LUAD and LUSC, especially at the early cancer stages. Our results revealed the difference of LUAD and LUSC from the immune response point of view, and provided new clues for the differential treatment of LUAD and LUSC.