The TACC domain identifies a family of centrosomal proteins that can interact with microtubules

The landscape of FGFR-TACC fusion in adult glioblastoma: From bench to bedside

Glioblastoma (GBM) is a lethal central nervous system tumor, characterized by extensive genomic alterations and high intra-tumoral heterogeneity. Gene fusions, derived from chromosomal translocations, deletions, and inversions, were increasingly recognized as key carcinogenic events, with the highest frequency of FGFR-TACC fusion in glioblastoma. As reported, FGFR3-TACC3 fusion mostly coexists with wild-type IDH status, and associates with better prognosis. Mechanistically, FGFR3-TACC3 fusions can constitutively activate non-canonical FGFR downstream pathways, induce aneuploidy, and participate in mitochondrial metabolism, thereby promoting cell proliferation and tumorigenesis. These functions, whether based on FGFR3 phosphorylation or not, are predominantly attributed to the specific domain of TACC3 that involved in regulating the localization and activation of fusion products. Several preclinical studies and clinical trials are being performed to evaluate the efficacy and safety of the FGFR-TACC fusion as a personalised therapeutic target, including the treatments with tyrosine kinase inhibitors, metabolic inhibitors, HSP90 inhibitors, coiled-coil peptide-mimetics, and targeted protein degraders. A subset of populations with FGFR-TACC-positive glioblastoma, after refined molecular screening strategies, may benefit from targeted therapies. Despite major progress in biotechnology, our understanding on the role of fusion events in glioblastoma represented by the FGFR-TACC is still in its infancy. Here, we highlight recent progress on FGFR-TACC fusion in human glioblastoma, emphasizing their molecular mechanisms and potential clinical value.

An Aurora kinase A-BOD1L1-PP2A B56 axis promotes chromosome segregation fidelity

Cancer cells are often aneuploid and frequently display elevated rates of chromosome mis-segregation, called chromosomal instability (CIN). CIN is caused by hyperstable kinetochore-microtubule (K-MT) attachments that reduce the correction efficiency of erroneous K-MT attachments. UMK57, a chemical agonist of the protein MCAK (mitotic centromere-associated kinesin), improves chromosome segregation fidelity in CIN cancer cells by destabilizing K-MT attachments, but cells rapidly develop resistance. To determine the mechanism, we performed unbiased screens, which revealed increased phosphorylation in cells adapted to UMK57 at Aurora kinase A phosphoacceptor sites on BOD1L1 (protein biorientation defective 1-like-1). BOD1L1 depletion or Aurora kinase A inhibition eliminated resistance to UMK57. BOD1L1 localizes to spindles/kinetochores during mitosis, interacts with the PP2A phosphatase, and regulates phosphorylation levels of kinetochore proteins, chromosome alignment, mitotic progression, and fidelity. Moreover, the BOD1L1 gene is mutated in a subset of human cancers, and BOD1L1 depletion reduces cell growth in combination with clinically relevant doses of Taxol or Aurora kinase A inhibitor.

Centrioles generate two scaffolds with distinct biophysical properties to build mitotic centrosomes

Mitotic centrosomes assemble when centrioles recruit large amounts of pericentriolar material (PCM) around themselves. The PCM comprises hundreds of proteins, and there is much debate about its physical nature. Here, we show that Drosophila Spd-2 (human CEP192) fluxes out from centrioles, recruiting Polo and Aurora A kinases to catalyze the assembly of two distinct mitotic-PCM scaffolds: a Polo-dependent Cnn scaffold, and an Aurora A-dependent TACC scaffold, which exhibit solid- and liquid-like behaviors, respectively. Both scaffolds can independently recruit PCM proteins, but both are required for proper centrosome assembly, with the Cnn scaffold providing mechanical strength, and the TACC scaffold concentrating centriole and centrosome proteins. Recruiting Spd-2 to synthetic beads injected into early embryos reconstitutes key aspects of mitotic centrosome assembly on the bead surface, and this depends on Spd-2's ability to recruit Polo and Aurora A. Thus, Spd-2 orchestrates the assembly of two scaffolds, with distinct biophysical properties, that cooperate to build mitotic centrosomes in flies.

CEP192 localises mitotic Aurora-A activity by priming its interaction with TPX2

Aurora-A is an essential cell-cycle kinase with critical roles in mitotic entry and spindle dynamics. These functions require binding partners such as CEP192 and TPX2, which modulate both kinase activity and localisation of Aurora-A. Here we investigate the structure and role of the centrosomal Aurora-A:CEP192 complex in the wider molecular network. We find that CEP192 wraps around Aurora-A, occupies the binding sites for mitotic spindle-associated partners, and thus competes with them. Comparison of two different Aurora-A conformations reveals how CEP192 modifies kinase activity through the site used for TPX2-mediated activation. Deleting the Aurora-A-binding interface in CEP192 prevents centrosomal accumulation of Aurora-A, curtails its activation-loop phosphorylation, and reduces spindle-bound TPX2:Aurora-A complexes, resulting in error-prone mitosis. Thus, by supplying the pool of phosphorylated Aurora-A necessary for TPX2 binding, CEP192:Aurora-A complexes regulate spindle function. We propose an evolutionarily conserved spatial hierarchy, which protects genome integrity through fine-tuning and correctly localising Aurora-A activity.

A genome-wide association study identifies a locus associated with knee extension strength in older Japanese individuals

Sarcopenia is a common skeletal muscle disease in older people. Lower limb muscle strength is a good predictive value for sarcopenia; however, little is known about its genetic components. Here, we conducted a genome-wide association study (GWAS) for knee extension strength in a total of 3452 Japanese aged 60 years or older from two independent cohorts. We identified a significant locus, rs10749438 which is an intronic variant in TACC2 (transforming acidic coiled-coil-containing 2) (P = 4.2 × 10-8). TACC2, encoding a cytoskeleton-related protein, is highly expressed in skeletal muscle, and is reported as a target of myotonic dystrophy 1-associated splicing alterations. These suggest that changes in TACC2 expression are associated with variations in muscle strength in older people. The association was consistently observed in young and middle-aged subjects. Our findings would shed light on genetic components of lower limb muscle strength and indicate TACC2 as a potential therapeutic target for sarcopenia.

Targeting TACC3 Induces Immunogenic Cell Death and Enhances T-DM1 Response in HER2-Positive Breast Cancer

Trastuzumab emtansine (T-DM1) was the first and one of the most successful antibody-drug conjugates (ADC) approved for treating refractory HER2-positive breast cancer. Despite its initial clinical efficacy, resistance is unfortunately common, necessitating approaches to improve response. Here, we found that in sensitive cells, T-DM1 induced spindle assembly checkpoint (SAC)-dependent immunogenic cell death (ICD), an immune-priming form of cell death. The payload of T-DM1 mediated ICD by inducing eIF2α phosphorylation, surface exposure of calreticulin, ATP and HMGB1 release, and secretion of ICD-related cytokines, all of which were lost in resistance. Accordingly, ICD-related gene signatures in pretreatment samples correlated with clinical response to T-DM1-containing therapy, and increased infiltration of antitumor CD8+ T cells in posttreatment samples was correlated with better T-DM1 response. Transforming acidic coiled-coil containing 3 (TACC3) was overexpressed in T-DM1-resistant cells, and T-DM1 responsive patients had reduced TACC3 protein expression whereas nonresponders exhibited increased TACC3 expression during T-DM1 treatment. Notably, genetic or pharmacologic inhibition of TACC3 restored T-DM1-induced SAC activation and induction of ICD markers in vitro. Finally, TACC3 inhibition in vivo elicited ICD in a vaccination assay and potentiated the antitumor efficacy of T-DM1 by inducing dendritic cell maturation and enhancing intratumoral infiltration of cytotoxic T cells. Together, these results illustrate that ICD is a key mechanism of action of T-DM1 that is lost in resistance and that targeting TACC3 can restore T-DM1-mediated ICD and overcome resistance.

SIGNIFICANCE

Loss of induction of immunogenic cell death in response to T-DM1 leads to resistance that can be overcome by targeting TACC3, providing an attractive strategy to improve the efficacy of T-DM1.

The oncogene cyclin D1 promotes bipolar spindle integrity under compressive force

The mitotic spindle is the bipolar, microtubule-based structure that segregates chromosomes at each cell division. Aberrant spindles are frequently observed in cancer cells, but how oncogenic transformation affects spindle mechanics and function, particularly in the mechanical context of solid tumors, remains poorly understood. Here, we constitutively overexpress the oncogene cyclin D1 in human MCF10A cells to probe its effects on spindle architecture and response to compressive force. We find that cyclin D1 overexpression increases the incidence of spindles with extra poles, centrioles, and chromosomes. However, it also protects spindle poles from fracturing under compressive force, a deleterious outcome linked to multipolar cell divisions. Our findings suggest that cyclin D1 overexpression may adapt cells to increased compressive stress, possibly contributing to its prevalence in cancers such as breast cancer by allowing continued proliferation in mechanically challenging environments.

An Aurora kinase A-BOD1L1-PP2A B56 Axis promotes chromosome segregation fidelity

Cancer cells are often aneuploid and frequently display elevated rates of chromosome missegregation in a phenomenon called chromosomal instability (CIN). CIN is commonly caused by hyperstable kinetochore-microtubule (K-MT) attachments that reduces the efficiency of correction of erroneous K-MT attachments. We recently showed that UMK57, a chemical agonist of MCAK (alias KIF2C) improves chromosome segregation fidelity in CIN cancer cells although cells rapidly develop adaptive resistance. To determine the mechanism of resistance we performed unbiased proteomic screens which revealed increased phosphorylation in cells adapted to UMK57 at two Aurora kinase A phosphoacceptor sites on BOD1L1 (alias FAM44A). BOD1L1 depletion or Aurora kinase A inhibition eliminated resistance to UMK57 in CIN cancer cells. BOD1L1 localizes to spindles/kinetochores during mitosis, interacts with the PP2A phosphatase, and regulates phosphorylation levels of kinetochore proteins, chromosome alignment, mitotic progression and fidelity. Moreover, the BOD1L1 gene is mutated in a subset of human cancers, and BOD1L1 depletion reduces cell growth in combination with clinically relevant doses of taxol or Aurora kinase A inhibitor. Thus, an Aurora kinase A -BOD1L1-PP2A axis promotes faithful chromosome segregation during mitosis.

Male meiotic spindle poles are stabilized by TACC3 and cKAP5/chTOG differently from female meiotic or somatic mitotic spindles in mice

Transforming acidic acid coiled-coil protein 3 (TACC3) and cytoskeleton associated protein 5 (cKAP5; or colonic hepatic tumor overexpressed gene, chTOG) are vital for spindle assembly and stabilization initiated through TACC3 Aurora-A kinase interaction. Here, TACC3 and cKAP5/chTOG localization with monospecific antibodies is investigated in eGFP-centrin-2- expressing mouse meiotic spermatocytes. Both proteins bind spermatocyte spindle poles but neither kinetochore nor interpolar microtubules, unlike in mitotic mouse fibroblasts or female meiotic oocyte spindles. Spermatocytes do not display a liquid-like spindle domain (LISD), although fusing them into maturing oocytes generates LISD-like TACC3 condensates around sperm chromatin but sparse microtubule assembly. Microtubule inhibitors do not reduce TACC3 and cKAP5/chTOG spindle pole binding. MLN 8237 Aurora-A kinase inhibitor removes TACC3, not cKAP5/chTOG, disrupting spindle organization, chromosome alignment, and impacting spindle pole γ-tubulin intensity. The LISD disruptor 1,6-hexanediol abolished TACC3 in spermatocytes, impacting spindle bipolarity and chromosome organization. Cold microtubule disassembly and rescue experiments in the presence of 1,6-hexanediol reinforce the concept that spermatocyte TACC3 spindle pole presence is not required for spindle pole microtubule assembly. Collectively, meiotic spermatocytes without a LISD localize TACC3 and cKAP5/chTOG exclusively at spindle poles to support meiotic spindle pole stabilization during male meiosis, different from either female meiosis or mitosis.

The Multiple Roles of LCCL Domain-Containing Proteins for Malaria Parasite Transmission

Multi-protein complexes are crucial for various essential biological processes of the malaria parasite Plasmodium, such as protein synthesis, host cell invasion and adhesion. Especially during the sexual phase of the parasite, which takes place in the midgut of the mosquito vector, protein complexes are required for fertilization, sporulation and ultimately for the successful transmission of the parasite. Among the most noticeable protein complexes of the transmission stages are the ones formed by the LCCL domain-containing protein family that play critical roles in the generation of infective sporozoites. The six members of this protein family are characterized by numerous adhesive modules and domains typically found in secreted proteins. This review summarizes the findings of expression and functional studies on the LCCL domain-containing proteins of the human pathogenic P. falciparum and the rodent-infecting P. berghei and discusses the common features and differences of the homologous proteins.

Effects of small molecules on neurogenesis: Neuronal proliferation and differentiation

Neurons are believed to be non-proliferating cells. However, neuronal stem cells are still present in certain areas of the adult brain, although their proliferation diminishes with age. Just as with other cells, their proliferation and differentiation are modulated by various mechanisms. These mechanisms are foundational to the strategies developed to induce neuronal proliferation and differentiation, with potential therapeutic applications for neurodegenerative diseases. The most common among these diseases are Parkinson's disease and Alzheimer's disease, associated with the formation of β -amyloid (Aβ ) aggregates which cause a reduction in the number of neurons. Compounds such as LiCl, 4-aminothiazoles, Pregnenolone, ACEA, harmine, D2AAK1, methyl 3,4-dihydroxybenzoate, and shikonin may induce neuronal proliferation/differentiation through the activation of pathways: MAPK ERK, PI3K/AKT, NFκ B, Wnt, BDNF, and NPAS3. Moreover, combinations of these compounds can potentially transform somatic cells into neurons. This transformation process involves the activation of neuron-specific transcription factors such as NEUROD1, NGN2, ASCL1, and SOX2, which subsequently leads to the transcription of downstream genes, culminating in the transformation of somatic cells into neurons. Neurodegenerative diseases are not the only conditions where inducing neuronal proliferation could be beneficial. Consequently, the impact of pro-proliferative compounds on neurons has also been researched in mouse models of Alzheimer's disease.

TACC3: a multi-functional protein promoting cancer cell survival and aggressiveness

TACC3 is the most oncogenic member of the transforming acidic coiled-coil domain-containing protein (TACC) family. It is one of the major recruitment factors of distinct multi-protein complexes. TACC3 is localized to spindles, centrosomes, and nucleus, and regulates key oncogenic processes, including cell proliferation, migration, invasion, and stemness. Recently, TACC3 inhibition has been identified as a vulnerability in highly aggressive cancers, such as cancers with centrosome amplification (CA). TACC3 has spatiotemporal functions throughout the cell cycle; therefore, targeting TACC3 causes cell death in mitosis and interphase in cancer cells with CA. In the clinics, TACC3 is highly expressed and associated with worse survival in multiple cancers. Furthermore, TACC3 is a part of one of the most common fusions of FGFR, FGFR3-TACC3 and is important for the oncogenicity of the fusion. A detailed understanding of the regulation of TACC3 expression, its key partners, and molecular functions in cancer cells is vital for uncovering the most vulnerable tumors and maximizing the therapeutic potential of targeting this highly oncogenic protein. In this review, we summarize the established and emerging interactors and spatiotemporal functions of TACC3 in cancer cells, discuss the potential of TACC3 as a biomarker in cancer, and therapeutic potential of its inhibition.

Linear motif specificity in signaling through p38α and ERK2 mitogen-activated protein kinases

Mitogen-activated protein kinase (MAPK) cascades are essential for eukaryotic cells to integrate and respond to diverse stimuli. Maintaining specificity in signaling through MAPK networks is key to coupling distinct inputs to appropriate cellular responses. Docking sites-short linear motifs found in MAPK substrates, regulators, and scaffolds-can promote signaling specificity through selective interactions, but how they do so remains unresolved. Here, we screened a proteomic library for sequences interacting with the MAPKs extracellular signal-regulated kinase 2 (ERK2) and p38α, identifying selective and promiscuous docking motifs. Sequences specific for p38α had high net charge and lysine content, and selective binding depended on a pair of acidic residues unique to the p38α docking interface. Finally, we validated a set of full-length proteins harboring docking sites selected in our screens to be authentic MAPK interactors and substrates. This study identifies features that help define MAPK signaling networks and explains how specific docking motifs promote signaling integrity.

Non-canonical functions of a mutant TSC2 protein in mitotic division

Tuberous Sclerosis Complex (TSC) is a debilitating developmental disorder characterized by a variety of clinical manifestations. TSC is caused by mutations in the TSC1 or TSC2 genes, which encode the hamartin/tuberin proteins respectively. These proteins function as a heterodimer that negatively regulates the mechanistic Target of Rapamycin Complex 1 (mTORC1). TSC research has focused on the effects of mTORC1, a critical signaling hub, on regulation of diverse cell processes including metabolism, cell growth, translation, and neurogenesis. However, non-canonical functions of TSC2 are not well studied, and the potential disease-relevant biological mechanisms of mutations affecting these functions are not well understood. We observed aberrant multipolar mitotic division, a novel phenotype, in TSC2 mutant iPSCs. The multipolar phenotype is not meaningfully affected by treatment with the inhibitor rapamycin. We further observed dominant negative activity of the mutant form of TSC2 in producing the multipolar division phenotype. These data expand the knowledge of TSC2 function and pathophysiology which will be highly relevant to future treatments for patients with TSC.

Rare FGFR fusion genes in cervical cancer and transcriptome-based subgrouping of patients with a poor prognosis

BACKGROUND

Although cervical cancer is often characterized as preventable, its incidence continues to increase in low- and middle-income countries, underscoring the need to develop novel therapeutics for this disease.This study assessed the distribution of fusion genes across cancer types and used an RNA-based classification to divide cervical cancer patients with a poor prognosis into subgroups.

MATERIAL AND METHODS

RNA sequencing of 116 patients with cervical cancer was conducted. Fusion genes were extracted using StarFusion program. To identify a high-risk group for recurrence, 65 patients who received postoperative adjuvant therapy were subjected to non-negative matrix factorization to identify differentially expressed genes between recurrent and nonrecurrent groups.

RESULTS

We identified three cases with FGFR3-TACC3 and one with GOPC-ROS1 fusion genes as potential targets. A search of publicly available data from cBioPortal (21,789 cases) and the Center for Cancer Genomics and Advanced Therapeutics (32,608 cases) showed that the FGFR3 fusion is present in 1.5% and 0.6% of patients with cervical cancer, respectively. The frequency of the FGFR3 fusion gene was higher in cervical cancer than in other cancers, regardless of ethnicity. Non-negative matrix factorization identified that the patients were classified into four Basis groups. Pathway enrichment analysis identified more extracellular matrix kinetics dysregulation in Basis 3 and more immune system dysregulation in Basis 4 than in the good prognosis group. CIBERSORT analysis showed that the fraction of M1 macrophages was lower in the poor prognosis group than in the good prognosis group.

CONCLUSIONS

The distribution of FGFR fusion genes in patients with cervical cancer was determined by RNA-based analysis and used to classify patients into clinically relevant subgroups.

TACC3-ch-TOG interaction regulates spindle microtubule assembly by controlling centrosomal recruitment of γ-TuRC

γ-Tubulin ring complex (γ-TuRC), composed of γ-tubulin and multiple γ-tubulin complex proteins (GCPs), serves as the major microtubule nucleating complex in animal cells. However, several γ-TuRC-associated proteins have been shown to control its function. Centrosomal adaptor protein, TACC3, is one such γ-TuRC-interacting factor that is essential for proper mitotic spindle assembly across organisms. ch-TOG is another microtubule assembly promoting protein, which interacts with TACC3 and cooperates in mitotic spindle assembly. However, the mechanism how TACC3-ch-TOG interaction regulates microtubule assembly and the γ-TuRC functions at the centrosomes remain unclear. Here, we show that deletion of the ch-TOG-binding region in TACC3 enhances recruitment of the γ-TuRC proteins to centrosomes and aggravates spindle microtubule assembly in human cells. Loss of TACC3-ch-TOG binding imparts stabilization on TACC3 interaction with the γ-TuRC proteins and it does so by stimulating TACC3 phosphorylation and thereby enhancing phospho-TACC3 recruitment to the centrosomes. We also show that localization of ch-TOG at the centrosomes is substantially reduced and the same on the spindle microtubules is increased in its TACC3-unbound condition. Additional results reveal that ch-TOG depletion stimulates γ-tubulin localization on the spindles without significantly affecting the centrosomal γ-tubulin level. The results indicate that ch-TOG binding to TACC3 controls TACC3 phosphorylation and TACC3-mediated stabilization of the γ-TuRCs at the centrosomes. They also implicate that the spatio-temporal control of TACC3 phosphorylation via ch-TOG-binding ensures mitotic spindle assembly to the optimal level.

Targeting TACC3 represents a novel vulnerability in highly aggressive breast cancers with centrosome amplification

Centrosome amplification (CA) is a hallmark of cancer that is strongly associated with highly aggressive disease and worse clinical outcome. Clustering extra centrosomes is a major coping mechanism required for faithful mitosis of cancer cells with CA that would otherwise undergo mitotic catastrophe and cell death. However, its underlying molecular mechanisms have not been fully described. Furthermore, little is known about the processes and players triggering aggressiveness of cells with CA beyond mitosis. Here, we identified Transforming Acidic Coiled-Coil Containing Protein 3 (TACC3) to be overexpressed in tumors with CA, and its high expression is associated with dramatically worse clinical outcome. We demonstrated, for the first time, that TACC3 forms distinct functional interactomes regulating different processes in mitosis and interphase to ensure proliferation and survival of cancer cells with CA. Mitotic TACC3 interacts with the Kinesin Family Member C1 (KIFC1) to cluster extra centrosomes for mitotic progression, and inhibition of this interaction leads to mitotic cell death via multipolar spindle formation. Interphase TACC3 interacts with the nucleosome remodeling and deacetylase (NuRD) complex (HDAC2 and MBD2) in nucleus to inhibit the expression of key tumor suppressors (e.g., p21, p16 and APAF1) driving G1/S progression, and its inhibition blocks these interactions and causes p53-independent G1 arrest and apoptosis. Notably, inducing CA by p53 loss/mutation increases the expression of TACC3 and KIFC1 via FOXM1 and renders cancer cells highly sensitive to TACC3 inhibition. Targeting TACC3 by guide RNAs or small molecule inhibitors strongly inhibits growth of organoids and breast cancer cell line- and patient-derived xenografts with CA by induction of multipolar spindles, mitotic and G1 arrest. Altogether, our results show that TACC3 is a multifunctional driver of highly aggressive breast tumors with CA and that targeting TACC3 is a promising approach to tackle this disease.

The mechanism of acentrosomal spindle assembly in human oocytes

Meiotic spindle assembly ensures proper chromosome segregation in oocytes. However, the mechanisms behind spindle assembly in human oocytes remain largely unknown. We used three-dimensional high-resolution imaging of more than 2000 human oocytes to identify a structure that we named the human oocyte microtubule organizing center (huoMTOC). The proteins TACC3, CCP110, CKAP5, and DISC1 were found to be essential components of the huoMTOC. The huoMTOC arises beneath the oocyte cortex and migrates adjacent to the nuclear envelope before nuclear envelope breakdown (NEBD). After NEBD, the huoMTOC fragments and relocates on the kinetochores to initiate microtubule nucleation and spindle assembly. Disrupting the huoMTOC led to spindle assembly defects and oocyte maturation arrest. These results reveal a physiological mechanism of huoMTOC-regulated spindle assembly in human oocytes.

Identifying the genes impacted by cell proliferation in proteomics and transcriptomics studies

Hypothesis-free high-throughput profiling allows relative quantification of thousands of proteins or transcripts across samples and thereby identification of differentially expressed genes. It is used in many biological contexts to characterize differences between cell lines and tissues, identify drug mode of action or drivers of drug resistance, among others. Changes in gene expression can also be due to confounding factors that were not accounted for in the experimental plan, such as change in cell proliferation. We combined the analysis of 1,076 and 1,040 cell lines in five proteomics and three transcriptomics data sets to identify 157 genes that correlate with cell proliferation rates. These include actors in DNA replication and mitosis, and genes periodically expressed during the cell cycle. This signature of cell proliferation is a valuable resource when analyzing high-throughput data showing changes in proliferation across conditions. We show how to use this resource to help in interpretation of in vitro drug screens and tumor samples. It informs on differences of cell proliferation rates between conditions where such information is not directly available. The signature genes also highlight which hits in a screen may be due to proliferation changes; this can either contribute to biological interpretation or help focus on experiment-specific regulation events otherwise buried in the statistical analysis.

FGFR3-TACCs3 Fusions and Their Clinical Relevance in Human Glioblastoma

Oncogenic fusion genes have emerged as successful targets in several malignancies, such as chronic myeloid leukemia and lung cancer. Fusion of the fibroblast growth receptor 3 and the transforming acidic coiled coil containing protein—FGFR3-TACC3 fusion—is prevalent in 3–4% of human glioblastoma. The fusion protein leads to the constitutively activated kinase signaling of FGFR3 and thereby promotes cell proliferation and tumor progression. The subgroup of FGFR3-TACC3 fusion-positive glioblastomas presents with recurrent clinical and histomolecular characteristics, defining a distinctive subtype of IDH-wildtype glioblastoma. This review aims to provide an overview of the available literature on FGFR3-TACC3 fusions in glioblastoma and possible implications for actual clinical practice.

Decoding the PITX2-controlled genetic network in atrial fibrillation

Atrial fibrillation (AF), the most common sustained cardiac arrhythmia and a major risk factor for stroke, often arises through ectopic electrical impulses derived from the pulmonary veins (PVs). Sequence variants in enhancers controlling expression of the transcription factor PITX2, which is expressed in the cardiomyocytes (CMs) of the PV and left atrium (LA), have been implicated in AF predisposition. Single nuclei multiomic profiling of RNA and analysis of chromatin accessibility combined with spectral clustering uncovered distinct PV- and LA-enriched CM cell states. Pitx2-mutant PV and LA CMs exhibited gene expression changes consistent with cardiac dysfunction through cell type-distinct, PITX2-directed, cis-regulatory grammars controlling target gene expression. The perturbed network targets in each CM were enriched in distinct human AF predisposition genes, suggesting combinatorial risk for AF genesis. Our data further reveal that PV and LA Pitx2-mutant CMs signal to endothelial and endocardial cells through BMP10 signaling with pathogenic potential. This work provides a multiomic framework for interrogating the basis of AF predisposition in the PVs of humans.

Recent advances in IAP-based PROTACs (SNIPERs) as potential therapeutic agents

Proteolytic targeting chimaeras (PROTACs) have been developed as an effective technology for targeted protein degradation. PROTACs are heterobifunctional molecules that can trigger the polyubiquitination of proteins of interest (POIs) by recruiting the ubiquitin-proteasome system, thereby inhibiting the intracellular level of POIs. To date, a variety of small-molecule PROTACs (CRBN, VHL, IAP, and MDM2-based PROTACs) have been developed. IAP-based PROTACs, also known as specific and nongenetic IAP-dependent protein erasers (SNIPERs), are used to degrade the target proteins closely related to diseases. Their structures consist of three parts, including target protein ligand, E3 ligase ligand, and the linker between them. So far, many SNIPERs have been extensively studied worldwide and have performed well in multiple diseases, especially cancer. In this review, we will present the most relevant advances in the field of SNIPERs and provide our perspective on the opportunities and challenges for SNIPERs to become therapeutic agents.

A Potential Strategy for Treatment of Neurodegenerative Disorders by Regulation of Adult Hippocampal Neurogenesis in Human Brain

Abstract:

Adult hippocampal neurogenesis is a multistage mechanism that continues throughout the lifespan of human and non-human mammals. These adult-born neurons in the central nervous system (CNS) play a significant role in various hippocampus-dependent processes, including learning, mood regulation, pattern recognition, etc. Reduction of adult hippocampal neurogenesis, caused by multiple factors such as neurological disorders and aging, would impair neuronal proliferation and differentiation and result in memory loss. Accumulating studies have indicated that functional neuron impairment could be restored by promoting adult hippocampal neurogenesis. In this review, we summarized the small molecules that could efficiently promote the process of adult neurogenesis, particularly the agents that have the capacity of crossing the blood-brain barrier (BBB), and showed in vivo efficacy in mammalian brains. This may pave the way for the rational design of drugs to treat humnan neurodegenerative disorders in the future.

Centrosome-dependent microtubule modifications set the conditions for axon formation

Microtubule (MT) modifications are critical during axon development, with stable MTs populating the axon. How these modifications are spatially coordinated is unclear. Here, via high-resolution microscopy, we show that early developing neurons have fewer somatic acetylated MTs restricted near the centrosome. At later stages, however, acetylated MTs spread out in soma and concentrate in growing axon. Live imaging in early plated neurons of the MT plus-end protein, EB3, show increased displacement and growth rate near the MTOC, suggesting local differences that might support axon selection. Moreover, F-actin disruption in early developing neurons, which show fewer somatic acetylated MTs, does not induce multiple axons, unlike later stages. Overexpression of centrosomal protein 120 (Cep120), which promotes MT acetylation/stabilization, induces multiple axons, while its knockdown downregulates proteins modulating MT dynamics and stability, hampering axon formation. Collectively, we show how centrosome-dependent MT modifications contribute to axon formation.

LINC01140 inhibits nonsmall cell lung cancer progression and cisplatin resistance through the miR-4742-5p/TACC1 axis

Recent studies show that lncRNAs participate in drug resistance and nonsmall cell lung cancer (NSCLC) progression. This study aimed to study the roles and mechanisms of long intergenic nonprotein coding RNA 01140 (LINC01140) in regulating NSCLC progression and drug resistance. Real-time quantitative polymerase chain reaction and western blot analysis were used to detect LINC01140, miR-4742-5p, and transforming acidic coiled-coil 1 (TACC1) expression in NSCLC cells. The interaction between two molecules was examined by luciferase reporter and/or RNA immunoprecipitation assays. Cell invasion, apoptosis, and cisplatin cytotoxicity were assessed by transwell invasion assay, flow cytometry analysis, and CCK-8 assay, respectively. LINC01140 was downregulated and miR-4742-5p was upregulated in NSCLC. LINC01140 inhibited miR-4742-5p expression by competitively binding to miR-4742-5p, while miR-4742-5p targeted TACC1 to inhibit TACC1 expression in NSCLC cells. LINC01140 enrichment repressed the invasive potential and cisplatin resistance and triggered apoptosis, which was reversed by miR-4742-5p overexpression. miR-4742-5p inhibition suppressed cell invasion and cisplatin resistance and accelerated apoptosis in NSCLC cells, while TACC1 silencing abolished these effects. Mechanistically, LINC01140 positively regulated TACC1 expression by sponging miR-4742-5p. In conclusion, LINC01140 inhibited NSCLC progression and cisplatin resistance via functioning as a ceRNA for miR-4742-5p to modulate TACC1.

Development of a degrader against oncogenic fusion protein FGFR3-TACC3

Fibroblast growth factor receptor 3-transforming acidic coiled-coil containing protein 3 (FGFR3-TACC3), which has been identified in many cancers such as glioblastoma and bladder cancer, is a potent oncogenic fusion protein that induces constitutive activation of FGFR signaling, resulting in uncontrolled cell proliferation. Although several tyrosine kinase inhibitors against FGFR are currently under development, resistance to such types of inhibitors in patients has become a concern. In this study, a chimeric molecule SNIPER(TACC3)-11 (5a) was developed and found to reduce FGFR3-TACC3 levels effectively. Compound 5a conjugated KHS108 (a TACC3 ligand) to an LCL161 derivative (11) (an inhibitor of apoptosis protein [IAP] ligand) with a PEG linker (n = 2). Mechanistical analysis showed that cellular IAP1 was required for the reduction of FGFR3-TACC3 levels. Consistent with the decrease in FGFR3-TACC3 levels, compound 5a suppressed the growth of FGFR3-TACC3 positive cells. Thus, compound 5a is a candidate therapeutic with a novel drug modality against cancers that exhibit FGFR3-TACC3-dependent proliferation and exerts pharmacological effects distinct from FGFR3 kinase inhibitors because it lacks substructures crucial for kinase inhibition.

Beyond Protein Synthesis; The Multifaceted Roles of Tuberin in Cell Cycle Regulation

The ability of cells to sense diverse environmental signals, including nutrient availability and conditions of stress, is critical for both prokaryotes and eukaryotes to mount an appropriate physiological response. While there is a great deal known about the different biochemical pathways that can detect and relay information from the environment, how these signals are integrated to control progression through the cell cycle is still an expanding area of research. Over the past three decades the proteins Tuberin, Hamartin and TBC1D7 have emerged as a large protein complex called the Tuberous Sclerosis Complex. This complex can integrate a wide variety of environmental signals to control a host of cell biology events including protein synthesis, cell cycle, protein transport, cell adhesion, autophagy, and cell growth. Worldwide efforts have revealed many molecular pathways which alter Tuberin post-translationally to convey messages to these important pathways, with most of the focus being on the regulation over protein synthesis. Herein we review the literature supporting that the Tuberous Sclerosis Complex plays a critical role in integrating environmental signals with the core cell cycle machinery.

With the Permission of Microtubules: An Updated Overview on Microtubule Function During Axon Pathfinding

During the establishment of neural circuitry axons often need to cover long distances to reach remote targets. The stereotyped navigation of these axons defines the connectivity between brain regions and cellular subtypes. This chemotrophic guidance process mostly relies on the spatio-temporal expression patterns of extracellular proteins and the selective expression of their receptors in projection neurons. Axon guidance is stimulated by guidance proteins and implemented by neuronal traction forces at the growth cones, which engage local cytoskeleton regulators and cell adhesion proteins. Different layers of guidance signaling regulation, such as the cleavage and processing of receptors, the expression of co-receptors and a wide variety of intracellular cascades downstream of receptors activation, have been progressively unveiled. Also, in the last decades, the regulation of microtubule (MT) assembly, stability and interactions with the submembranous actin network in the growth cone have emerged as crucial effector mechanisms in axon pathfinding. In this review, we will delve into the intracellular signaling cascades downstream of guidance receptors that converge on the MT cytoskeleton of the growing axon. In particular, we will focus on the microtubule-associated proteins (MAPs) network responsible of MT dynamics in the axon and growth cone. Complementarily, we will discuss new evidences that connect defects in MT scaffold proteins, MAPs or MT-based motors and axon misrouting during brain development.

Human Cytomegalovirus Exploits TACC3 To Control Microtubule Dynamics and Late Stages of Infection

While it is well established that microtubules (MTs) facilitate various stages of virus replication, how viruses actively control MT dynamics and functions remains less well understood. Recent work has begun to reveal how several viruses exploit End-Binding (EB) proteins and their associated microtubule plus-end tracking proteins (+TIPs), in particular to enable loading of viral particles onto MTs for retrograde transport during early stages of infection. Distinct from other viruses studied to date, at mid- to late stages of its unusually protracted replication cycle, human cytomegalovirus (HCMV) increases the expression of all three EB family members. This occurs coincident with the formation of a unique structure, termed the assembly compartment (AC), which serves as a Golgi-derived MT organizing center. Together, the AC and distinct EB proteins enable HCMV to increase the formation of dynamic and acetylated microtubule subsets to regulate distinct aspects of the viral replication cycle. Here, we reveal that HCMV also exploits EB-independent +TIP pathways by specifically increasing the expression of transforming acidic coiled coil protein 3 (TACC3) to recruit the MT polymerase, chTOG, from initial sites of MT nucleation in the AC out into the cytosol, thereby increasing dynamic MT growth. Preventing TACC3 increases or depleting chTOG impaired MT polymerization, resulting in defects in early versus late endosome organization in and around the AC as well as defects in viral trafficking and spread. Our findings provide the first example of a virus that actively exploits EB-independent +TIP pathways to regulate MT dynamics and control late stages of virus replication. IMPORTANCE Diverse viruses rely on host cell microtubule networks to transport viral particles within the dense cytoplasmic environment and to control the broader architecture of the cell to facilitate their replication. However, precisely how viruses regulate the dynamic behavior and function of microtubule filaments remains poorly defined. We recently showed that the assembly compartment (AC) formed by human cytomegalovirus (HCMV) acts as a Golgi-derived microtubule organizing center. Here, we show that at mid- to late stages of infection, HCMV increases the expression of transforming acidic coiled coil protein 3 (TACC3) to control the localization of the microtubule polymerase, chTOG. This, in turn, enables HCMV to generate dynamic microtubule subsets that organize endocytic vesicles in and around the AC and facilitate the transport of new viral particles released into the cytosol. Our findings reveal the first instance of viral targeting of TACC3 to control microtubule dynamics and virus spread.

Transforming acidic coiled-coil protein-3: a novel marker for differential diagnosis and prognosis prediction in endocervical adenocarcinoma

Background

Endocervical adenocarcinoma (ECA) is further classified as human papillomavirus (HPV)-associated (HPVA) or non-HPVA (NHPVA), per the International Endocervical Adenocarcinoma Criteria and Classification (IECC). HPVA is a glandular tumor with stromal invasion and/or exophytic expansile-type invasion, associated with the typical molecular characteristics of high-risk HPV (HR-HPV) infection. Transforming acidic coiled-coil protein-3 (TACC3),an oncogene that is frequently abnormally expressed,represents a vital biomarker for multiple human malignancies. This study aimed to examine the role of TACC3 in the diagnosis and prognosis of ECA.

Methods

We analyzed 264 patients with ECA who underwent surgical resection, classifying their tumors into HPVA and NHPVA subtypes. The expression levels of TACC3, P16, MLH1, PMS2, MSH2, MSH6 and Ki-67 in tumors were evaluated by tissue microarray using immunohistochemistry (IHC). HPV subtypes were identified in formalin-fixed paraffin-embedded (FFPE) ECA tissues by the polymerase chain reaction (PCR).

Results

ECA samples showed increased TACC3 expression relative to adjacent non-carcinoma samples. TACC3 expression was higher in HPVA than in NHPA. In the HPVA subtype, high TACC3 expression was significantly correlated with P16-positive, Ki-67-high expression. Furthermore, TACC3 levels were significantly related to tumor histological type (P = 0.006), nerve invasion (P = 0.003), differentiation (P = 0.004), surgical margin (P = 0.012), parametrium invasion (P = 0.040), P16 expression (P < 0.001), and Ki-67 (P = 0.004). Additionally, Kaplan–Meier analysis showed that TACC3 upregulation was associated with poor overall survival (OS, P = 0.001), disease-free survival (DFS, P < 0.001), and recurrence survival (P < 0.001). Multivariate analysis indicated that elevated TACC3 expression served as a marker to independently predict ECA prognosis. ROC curve analyses indicated that TACC3, P16, and HPV subtypes showed similar utility for distinguishing HPVA from NHPVA, with areas under the ROC curves of 0.640, 0.649, and 0.675, respectively. The combination of TACC3 and HPV subtypes improved the diagnostic performance of ECA compared with TACC3, P16, and HPV subtypes alone.

Conclusions

Taken together, our findings identify that TACC3 is a promising complementary biomarker for diagnosis and prognosis for patients with ECA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-021-00298-z.

Oncogenic FGFR Fusions Produce Centrosome and Cilia Defects by Ectopic Signaling

A single primary cilium projects from most vertebrate cells to guide cell fate decisions. A growing list of signaling molecules is found to function through cilia and control ciliogenesis, including the fibroblast growth factor receptors (FGFR). Aberrant FGFR activity produces abnormal cilia with deregulated signaling, which contributes to pathogenesis of the FGFR-mediated genetic disorders. FGFR lesions are also found in cancer, raising a possibility of cilia involvement in the neoplastic transformation and tumor progression. Here, we focus on FGFR gene fusions, and discuss the possible mechanisms by which they function as oncogenic drivers. We show that a substantial portion of the FGFR fusion partners are proteins associated with the centrosome cycle, including organization of the mitotic spindle and ciliogenesis. The functions of centrosome proteins are often lost with the gene fusion, leading to haploinsufficiency that induces cilia loss and deregulated cell division. We speculate that this complements the ectopic FGFR activity and drives the FGFR fusion cancers.

Fibroblast Growth Factor Receptors (FGFRs) and Noncanonical Partners in Cancer Signaling

Increasing evidence indicates that success of targeted therapies in the treatment of cancer is context-dependent and is influenced by a complex crosstalk between signaling pathways and between cell types in the tumor. The Fibroblast Growth Factor (FGF)/FGF receptor (FGFR) signaling axis highlights the importance of such context-dependent signaling in cancer. Aberrant FGFR signaling has been characterized in almost all cancer types, most commonly non-small cell lung cancer (NSCLC), breast cancer, glioblastoma, prostate cancer and gastrointestinal cancer. This occurs primarily through amplification and over-expression of FGFR1 and FGFR2 resulting in ligand-independent activation. Mutations and translocations of FGFR1-4 are also identified in cancer. Canonical FGF-FGFR signaling is tightly regulated by ligand-receptor combinations as well as direct interactions with the FGFR coreceptors heparan sulfate proteoglycans (HSPGs) and Klotho. Noncanonical FGFR signaling partners have been implicated in differential regulation of FGFR signaling. FGFR directly interacts with cell adhesion molecules (CAMs) and extracellular matrix (ECM) proteins, contributing to invasive and migratory properties of cancer cells, whereas interactions with other receptor tyrosine kinases (RTKs) regulate angiogenic, resistance to therapy, and metastatic potential of cancer cells. The diversity in FGFR signaling partners supports a role for FGFR signaling in cancer, independent of genetic aberration.

Novel targetable FGFR2 and FGFR3 alterations in glioblastoma associate with aggressive phenotype and distinct gene expression programs

Prognostic molecular subgrouping of glioblastoma is an ongoing effort and the current classification includes IDH-wild-type and IDH-mutant entities, the latter showing significantly better prognosis. We performed a comparative integrated analysis of the FGFR glioblastoma subgroup consisting of 5 cases from a prospective 101-patient-cohort. FGFR alterations included FGFR2-TACC2 and FGFR2 amplifications arising in a multifocal IDH-mutant glioblastoma with unexpected 2.5-month patient survival, novel FGFR3 carboxy-terminal duplication and FGFR3-TLN1 fusion, and two previously described FGFR3-TACC3 fusions. The FGFR2 tumors showed additional mutations in SERPINE1/PAI-1 and MMP16, as part of extensive extracellular matrix remodeling programs. Whole transcriptomic analysis revealed common proliferation but distinct morphogenetic gene expression programs that correlated with tumor histology. The kinase program revealed EPHA3, LTK and ALK receptor tyrosine kinase overexpression in individual FGFR tumors. Paradoxically, all FGFR-fused glioblastomas shared strong PI3K and MAPK pathway suppression effected by SPRY, DUSP and AKAP12 inhibitors, whereas the FGFR2-TACC2 tumor elicited also EGFR suppression by ERRFI1 upregulation. This integrated analysis outlined the proliferation and morphogenetic expression programs in FGFR glioblastoma, and identified four novel, clinically targetable FGFR2 and FGFR3 alterations that confer aggressive phenotype and trigger canonical pathway feedback inhibition, with important therapeutic implications.

Co-expression of fibroblast growth factor receptor 3 with mutant p53, and its association with worse outcome in oropharyngeal squamous cell carcinoma

Fibroblast growth factor receptor 3 (FGFR3) is expressed in squamous cell carcinoma of the head and neck (SCCHN) including oropharyngeal squamous cell carcinoma (OPSCC) and is a potential therapeutic target. However, information on its correlation with other relevant cancer related proteins stratified by p16 status and its prognostic significance in OPSCC is limited. We examined FGFR3 expression and its correlation with clinical characteristics, p16 status, and mutant p53 (mp53) among 220 retrospectively collected OPSCC cases and 40 prospectively collected SCCHN cases, including a majority of OPSCC. Correlations of FGFR3 Weighted Index (WI) with p16 status and mp53 WI as well as its association with disease-free survival (DFS) and overall survival (OS) were evaluated. FGFR3 expression was detected in 61% and 70% of cases in cohorts 1 and 2, respectively. FGFR3 level was significantly higher in p16-negative tumors in both cohorts (p<0.001 and 0.006). FGFR3 expression was highly correlated with mp53 expression in both p16 + and p16- OPSCC (p<0.0001 and p = 0.0006, respectively). In cohort 1, univariate analysis showed that FGFR3 was associated with DFS but not OS. Kaplan-Meier analysis showed that higher FGFR3 and mp53 level correlated with worse DFS (p = 0.025) and OS (p = 0.009). As expected, p16 positive status was associated with improved OS and DFS (p<0.001 for both). Our results suggest that high FGFR3 expression is associated with p16 negative status and mp53 expression in OPSCC and correlates with a worse clinical outcome. The biological relationship between FGFR3 and mp53 in OPSCC deserves further investigation.

Defining endogenous TACC3-chTOG-clathrin-GTSE1 interactions at the mitotic spindle using induced relocalization

A multiprotein complex containing TACC3, clathrin and other proteins has been implicated in mitotic spindle stability. To disrupt this complex in an anti-cancer context, we need to understand its composition and how it interacts with microtubules. Induced relocalization of proteins in cells is a powerful way to analyze protein-protein interactions and, additionally, monitor where and when these interactions occur. We used CRISPR/Cas9 gene editing to add tandem FKBP-GFP tags to each complex member. The relocalization of endogenous tagged protein from the mitotic spindle to mitochondria and assessment of the effect on other proteins allowed us to establish that TACC3 and clathrin are core complex members and that chTOG (also known as CKAP5) and GTSE1 are ancillary to the complex, binding respectively to TACC3 and clathrin, but not each other. We also show that PIK3C2A, a clathrin-binding protein that was proposed to stabilize the TACC3-chTOG-clathrin-GTSE1 complex during mitosis, is not a member of the complex. This work establishes that targeting the TACC3-clathrin interface or their microtubule-binding sites are the two strategies most likely to disrupt spindle stability mediated by this multiprotein complex.

Phase Separation during Germline Development

Phase separation has emerged as a new key principle of intracellular organization. Phase-separated structures play diverse roles in various biological processes and pathogenesis of protein aggregation diseases. Recent work has revealed crucial functions for phase separation during germline development. Phase separation controls the assembly and segregation of germ granules that determine which embryonic cells become germ cells. Phase separation promotes the formation of the Balbiani body, a structure that stores organelles and RNAs during the prolonged prophase arrest of oocytes. Phase separation also facilitates meiotic recombination that prepares homologous chromosomes for segregation, and drives the formation of a liquid-like spindle domain that promotes spindle assembly in mammalian oocytes. We review how phase separation drives these essential steps during germline development.

TACC3 Regulates Microtubule Plus-End Dynamics and Cargo Transport in Interphase Cells

End-binding proteins (EBs) are widely viewed as master regulators of microtubule dynamics and function. Here, we show that while EB1 mediates the dynamic microtubule capture of herpes simplex virus type 1 (HSV-1) in fibroblasts, in neuronal cells, infection occurs independently of EBs through stable microtubules. Prompted by this, we find that transforming acid coiled-coil protein 3 (TACC3), widely studied in mitotic spindle formation, regulates the cytoplasmic localization of the microtubule polymerizing factor chTOG and influences microtubule plus-end dynamics during interphase to control infection in distinct cell types. Furthermore, perturbing TACC3 function in neuronal cells resulted in the formation of disorganized stable, detyrosinated microtubule networks and changes in cellular morphology, as well as impaired trafficking of both HSV-1 and transferrin. These trafficking defects in TACC3-depleted cells were reversed by the depletion of kinesin-1 heavy chains. As such, TACC3 is a critical regulator of interphase microtubule dynamics and stability that influences kinesin-1-based cargo trafficking.

While EB proteins are widely studied as master regulators of microtubule plus-end dynamics, Furey et al. report EB-independent regulation of microtubule arrays and cargo trafficking by the transforming acid coiled-coil-containing protein, TACC3. By controlling the formation of detyrosinated stable microtubule networks, TACC3 influences kinesin-1-based sorting of both host and pathogenic cargoes.

A liquid-like spindle domain promotes acentrosomal spindle assembly in mammalian oocytes

Mammalian oocytes segregate chromosomes with a microtubule spindle that lacks centrosomes, but the mechanisms by which acentrosomal spindles are organized and function are largely unclear. In this study, we identify a conserved subcellular structure in mammalian oocytes that forms by phase separation. This structure, which we term the liquid-like meiotic spindle domain (LISD), permeates the spindle poles and forms dynamic protrusions that extend well beyond the spindle. The LISD selectively concentrates multiple microtubule regulatory factors and allows them to diffuse rapidly within the spindle volume. Disruption of the LISD via different means disperses these factors and leads to severe spindle assembly defects. Our data suggest a model whereby the LISD promotes meiotic spindle assembly by serving as a reservoir that sequesters and mobilizes microtubule regulatory factors in proximity to spindle microtubules.

A Highly Potent TACC3 Inhibitor as a Novel Anticancer Drug Candidate

TACC3, a transforming acidic coiled-coil (TACC) family member, is frequently upregulated in a broad spectrum of cancers, including breast cancer. It plays critical roles in protecting microtubule stability and centrosome integrity that is often dysregulated in cancers; therefore, making TACC3 a highly attractive therapeutic target. Here, we identified a new TACC3-targeting chemotype, BO-264, through the screening of in-house compound collection. Direct interaction between BO-264 and TACC3 was validated by using several biochemical methods, including drug affinity responsive target stability, cellular thermal shift assay, and isothermal titration calorimetry. BO-264 demonstrated superior antiproliferative activity to the two currently reported TACC3 inhibitors, especially in aggressive breast cancer subtypes, basal and HER2+, via spindle assembly checkpoint-dependent mitotic arrest, DNA damage, and apoptosis, while the cytotoxicity against normal breast cells was negligible. Furthermore, BO-264 significantly decreased centrosomal TACC3 during both mitosis and interphase. BO-264 displayed potent antiproliferative activity (∼90% have less than 1 μmol/L GI₅₀ value) in the NCI-60 cell line panel compromising of nine different cancer types. Noteworthy, BO-264 significantly inhibited the growth of cells harboring FGFR3-TACC3 fusion, an oncogenic driver in diverse malignancies. Importantly, its oral administration significantly impaired tumor growth in immunocompromised and immunocompetent breast and colon cancer mouse models, and increased survival without any major toxicity. Finally, TACC3 expression has been identified as strong independent prognostic factor in breast cancer and strongly prognostic in several different cancers. Overall, we identified a novel and highly potent TACC3 inhibitor as a novel potential anticancer agent, inducing spindle abnormalities and mitotic cell death.

The role of fibroblast growth factors and their receptors in gliomas: the mutations involved

The central nervous system (CNS) comprises of neurons, which are responsible for impulse transmission, and glial cells, which surround neurons providing protection and nutrition. Glial cells are categorized into astrocytes, oligodendrocytes, microglial cells, and ependymal cells. Tumors forming from glial cells are called gliomas, and they are classified accordingly into astrocytomas, oligodendrogliomas, and ependymomas. Gliomas are characterized by high mortality rates and degree of malignancy, heterogeneity, and resistance to treatment. Among the molecular players implicated in glioma pathogenesis are members of the fibroblast growth factor (FGF) superfamily as well as their receptors (FGFRs). In the present study, we provide a review of the literature on the role of FGFs and FGFRs in glioma pathogenesis. We also demonstrate that FGFs, and particularly FGF1 and FGF2, bear a variety of mutations in gliomas, while FGFRs are also crucially involved. In fact, several studies show that in gliomas, FGFRs bear mutations, mainly in the tyrosine kinase domains. Specifically, it appears that FGFR1-TACC1 and FGFR3-TACC3 fusions are common in these receptors. A better understanding of the mutations and the molecular players involved in glioma formation will benefit the scientific community, leading to the development of more effective and innovative therapeutic approaches.

dTACC restricts bouton addition and regulates microtubule organization at the Drosophila neuromuscular junction

Regulation of the synaptic cytoskeleton is essential to proper neuronal development and wiring. Perturbations in neuronal microtubules (MTs) are associated with numerous pathologies, yet it remains unclear how changes in MTs may be coupled to synapse morphogenesis. Studies have identified many MT regulators that promote synapse growth. However, less is known about the factors that restrict growth, despite the potential links of synaptic overgrowth to severe neurological conditions. Here, we report that dTACC, which is implicated in MT assembly and stability, prevents synapse overgrowth at the Drosophila neuromuscular junction by restricting addition of new boutons throughout larval development. dTACC localizes to the axonal MT lattice and is required to maintain tubulin levels and the integrity of higher-order MT structures in motor axon terminals. While previous reports have demonstrated the roles of MT-stabilizing proteins in promoting synapse growth, our findings suggest that in certain contexts, MT stabilization may correlate with restricted growth.

Pretreatment TACC3 expression in locally advanced rectal cancer decreases the response to neoadjuvant chemoradiotherapy

Chemoradiotherapy combined with surgical resection is the standard treatment for locally advanced rectal cancer, but not all the patients respond to neoadjuvant treatment. Transforming acidic coiled-coil protein-3 (TACC3) is frequently aberrantly expressed in rectal cancer tissue. In this study, we investigated whether TACC3 could serve as a biomarker predictive of the efficacy of chemoradiotherapy. In all, 152 rectal cancer patients with tumor tissue collected at biopsy and set aside before treatment were enrolled in this study. All patients received chemoradiotherapy and surgical resection. Immunohistochemically detected tumoral TACC3 expression significantly decreased sensitivity to chemoradiotherapy [risk ratio (RR) = 2.236, 95% confidence interval (CI): 1.447-3.456; P = 0.001] and thus the pathological complete response rate (P = 0.001). TACC3 knockdown using specific siRNA enhanced radiotherapy-induced decreases in proliferation and colony formation by HCT116 and SW480 cells and increased the incidence of radiotherapy-induced apoptosis. Cox multivariate analysis showed that TACC3 was a significant prognostic factor for overall survival (P = 0.017) and disease-free survival (P = 0.020). These findings suggest TACC3 expression may be predictive of chemoradiotherapy sensitivity and prognosis in locally advanced rectal cancer.

Progress on small-molecule proteolysis-targeting chimeras

Proteolysis-targeting chimeras (PROTACs) have received much attention for their promising therapeutic intervention in recent years. These molecules, with the mechanism of simultaneous recruitment of target protein and an E3 ligase, can trigger the cellular ubiquitin–proteasome system to degrade the target proteins. This article systematically introduces the mechanism of small-molecule PROTACs, and summarized the research progress of small-molecule PROTACs. The prospect for further application and the problems to be solved are also discussed.

Perspective: Potential Impact and Therapeutic Implications of Oncogenic PI3K Activation on Chromosomal Instability

Genetic activation of the class I PI3K pathway is very common in cancer. This mostly results from oncogenic mutations in PIK3CA, the gene encoding the ubiquitously expressed PI3Kα catalytic subunit, or from inactivation of the PTEN tumour suppressor, a lipid phosphatase that opposes class I PI3K signalling. The clinical impact of PI3K inhibitors in solid tumours, aimed at dampening cancer-cell-intrinsic PI3K activity, has thus far been limited. Challenges include poor drug tolerance, incomplete pathway inhibition and pre-existing or inhibitor-induced resistance. The principle of pharmacologically targeting cancer-cell-intrinsic PI3K activity also assumes that all cancer-promoting effects of PI3K activation are reversible, which might not be the case. Emerging evidence suggests that genetic PI3K pathway activation can induce and/or allow cells to tolerate chromosomal instability, which-even if occurring in a low fraction of the cell population-might help to facilitate and/or drive tumour evolution. While it is clear that such genomic events cannot be reverted pharmacologically, a role for PI3K in the regulation of chromosomal instability could be exploited by using PI3K pathway inhibitors to prevent those genomic events from happening and/or reduce the pace at which they are occurring, thereby dampening cancer development or progression. Such an impact might be most effective in tumours with clonal PI3K activation and achievable at lower drug doses than the maximum-tolerated doses of PI3K inhibitors currently used in the clinic.

Wolf-Hirschhorn Syndrome-Associated Genes Are Enriched in Motile Neural Crest Cells and Affect Craniofacial Development in Xenopus laevis

Wolf-Hirschhorn Syndrome (WHS) is a human developmental disorder arising from a hemizygous perturbation, typically a microdeletion, on the short arm of chromosome four. In addition to pronounced intellectual disability, seizures, and delayed growth, WHS presents with a characteristic facial dysmorphism and varying prevalence of microcephaly, micrognathia, cartilage malformation in the ear and nose, and facial asymmetries. These affected craniofacial tissues all derive from a shared embryonic precursor, the cranial neural crest (CNC), inviting the hypothesis that one or more WHS-affected genes may be critical regulators of neural crest development or migration. To explore this, we characterized expression of multiple genes within or immediately proximal to defined WHS critical regions, across the span of craniofacial development in the vertebrate model system Xenopus laevis. This subset of genes, whsc1, whsc2, letm1, and tacc3, are diverse in their currently-elucidated cellular functions; yet we find that their expression demonstrates shared tissue-specific enrichment within the anterior neural tube, migratory neural crest, and later craniofacial structures. We examine the ramifications of this by characterizing craniofacial development and neural crest migration following individual gene depletion. We observe that several WHS-associated genes significantly impact facial patterning, cartilage formation, neural crest motility in vivo and in vitro, and can separately contribute to forebrain scaling. Thus, we have determined that numerous genes within and surrounding the defined WHS critical regions potently impact craniofacial patterning, suggesting their role in WHS presentation may stem from essential functions during neural crest-derived tissue formation.

Centrosome Amplification and Tumorigenesis: Cause or Effect?

Centrosome amplification is a feature of multiple tumour types and has been postulated to contribute to both tumour initiation and tumour progression. This chapter focuses on the mechanisms by which an increase in centrosome number might lead to an increase or decrease in tumour progression and the role of proteins that regulate centrosome number in driving tumorigenesis.

Coordination of Embryogenesis by the Centrosome in Drosophila melanogaster

The first 3 h of Drosophila melanogaster embryo development are exemplified by rapid nuclear divisions within a large syncytium, transforming the zygote to the cellular blastoderm after 13 successive cleavage divisions. As the syncytial embryo develops, it relies on centrosomes and cytoskeletal dynamics to transport nuclei, maintain uniform nuclear distribution throughout cleavage cycles, ensure generation of germ cells, and coordinate cellularization. For the sake of this review, we classify six early embryo stages that rely on processes coordinated by the centrosome and its regulation of the cytoskeleton. The first stage features migration of one of the female pronuclei toward the male pronucleus following maturation of the first embryonic centrosomes. Two subsequent stages distribute the nuclei first axially and then radially in the embryo. The remaining three stages involve centrosome-actin dynamics that control cortical plasma membrane morphogenesis. In this review, we highlight the dynamics of the centrosome and its role in controlling the six stages that culminate in the cellularization of the blastoderm embryo.

High expression of TACC2 in hepatocellular carcinoma is associated with poor prognosis

BACKGROUND:

Transforming acidic coiled-coil protein 2 (TACC2) is a member of TACC family proteins which is mainly involved in the stabilization of spindles and regulation of microtubule dynamics through interactions with molecules involved in centrosomes/microtubules. TACC2 is involved in tumorigenesis of variety of cancers but the clinical significance of TACC2 protein in hepatocellular carcinoma (HCC) is still unclear.

OBJECTIVE:

This study aims to investigate the expression of TACC2 in HCC and determine if clinical significance and prognostic relevance exists.

METHODS:

We performed quantitative PCR (qPCR) and western blot to examine TACC2 mRNA and protein expression in paired HCC tissues and matched adjacent non-cancerous tissues. Immunohistochemistry was performed in 106 postoperative HCC samples.

RESULTS:

There was higher expression of TACC2 protein and mRNA in HCC tissue. Immunohistochemistry analysis showed high expression of TACC2 in HCC tissue and was significantly associated with the capsular extension, tumor recurrence and shortened overall and disease free survival. The Cox regression analysis suggested that a high expression of TACC2 was an independent prognostic factor for HCC patients.

CONCLUSION:

This finding suggests that TACC2 may be a useful tool as a candidate biomarker to predict the recurrence and prognosis of HCC.