Nucleophosmin and cancer

Physical Chemistry of Cellular Liquid-Phase Separation

Compartmentalization of biochemical processes is essential for cell function. Although membrane-bound organelles are well studied in this context, recent work has shown that phase separation is a key contributor to cellular compartmentalization through the formation of liquid-like membraneless organelles (MLOs). In this Minireview, the key mechanistic concepts that underlie MLO dynamics and function are first briefly discussed, including the relevant noncovalent interaction chemistry and polymer physical chemistry. Next, a few examples of MLOs and relevant proteins are given, along with their functions, which highlight the relevance of the above concepts. The developing area of active matter and non-equilibrium systems, which can give rise to unexpected effects in fluctuating cellular conditions, are also discussed. Finally, our thoughts for emerging and future directions in the field are discussed, including in vitro and in vivo studies of MLO physical chemistry and function.

The acute myeloid leukemia-associated Nucleophosmin 1 gene mutations dictate amyloidogenicity of the C-terminal domain

Nucleophosmin 1 (NPM1) is a nucleus-cytoplasm shuttling protein ubiquitously expressed and highly conserved. It is involved in many cellular processes and its gene is mutated in ~ 50-60% of Acute Myeloid Leukemia (AML) patients. These mutations cause its cytoplasmic mislocation and accumulation (referred to as NPM1c+) and open the door to rational targeted therapy for AML diseases with mutated NPM1. Currently, there is limited knowledge on the mechanism of action of NPM1c+ and on structural determinants of the leukemogenic potential of AML mutations. Numerous previous studies outlined an unexpected amyloid-like aggregation tendency of several regions located in the C-terminal domain that, in wild-type form, fold as a three-helical-bundle. Here, using a combination of different techniques including Thioflavin T fluorescence, congo red absorbance, CD spectroscopy, Scanning Electron Microscopy (SEM) and wide-angle X-ray scattering on a series of peptides bearing mutations, we evidence that the amyloidogenicity of NPM1 mutants is directly linked to AML. Noticeably, AML point mutations strongly affect the amyloid cytotoxic effects in neuroblastoma cells and the morphologies of deriving fibrils. This study paves the way to deepen our understanding of AML-associated NPM1 mutants, and could help to break new ground for the identification of novel drugs targeting NPM1c+ for treatment of AML.

Exome sequencing of the TCL1 mouse model for CLL reveals genetic heterogeneity and dynamics during disease development

The TCL1 mouse model is widely used to study pathophysiology, clonal evolution, and drug sensitivity or resistance of chronic lymphocytic leukemia (CLL). By performing whole exome sequencing, we present the genetic landscape of primary tumors from TCL1 mice and of TCL1 tumors serially transplanted into wild-type recipients to mimic clonal evolution. We show that similar to CLL patients, mutations in mice are frequently subclonal and heterogenous among different primary TCL1 mice. We further describe that this molecular heterogeneity mirrors heterogenous disease characteristics such as organ infiltration or CLL dependent T cell skewing. Similar to human CLL, we further observed the occurrence of novel mutations and structural variations during clonal evolution and found plasticity in the expansion of B cell receptor specific subclones. Thus, our results uncover that the genetic complexity, pathway dependence and clonal dynamics in mouse CLL are in relevant agreement to human CLL, and they are important to consider in future research using the TCL1 mouse for studying CLL.

Genetic variation and function of the HIV-1 Tat protein

Human immunodeficiency virus type 1 (HIV-1) encodes a transactivator of transcription (Tat) protein, which has several functions that promote viral replication, pathogenesis, and disease. Amino acid variation within Tat has been observed to alter the functional properties of Tat and, depending on the HIV-1 subtype, may produce Tat phenotypes differing from viruses' representative of each subtype and commonly used in in vivo and in vitro experimentation. The molecular properties of Tat allow for distinctive functional activities to be determined such as the subcellular localization and other intracellular and extracellular functional aspects of this important viral protein influenced by variation within the Tat sequence. Once Tat has been transported into the nucleus and becomes engaged in transactivation of the long terminal repeat (LTR), various Tat variants may differ in their capacity to activate viral transcription. Post-translational modification patterns based on these amino acid variations may alter interactions between Tat and host factors, which may positively or negatively affect this process. In addition, the ability of HIV-1 to utilize or not utilize the transactivation response (TAR) element within the LTR, based on genetic variation and cellular phenotype, adds a layer of complexity to the processes that govern Tat-mediated proviral DNA-driven transcription and replication. In contrast, cytoplasmic or extracellular localization of Tat may cause pathogenic effects in the form of altered cell activation, apoptosis, or neurotoxicity. Tat variants have been shown to differentially induce these processes, which may have implications for long-term HIV-1-infected patient care in the antiretroviral therapy era. Future studies concerning genetic variation of Tat with respect to function should focus on variants derived from HIV-1-infected individuals to efficiently guide Tat-targeted therapies and elucidate mechanisms of pathogenesis within the global patient population.

[Study of the effects and mechanism of all-trans retinoic acid on leukemic cell line U937 cells with NPM1 mutation]

Objective: To investigate the effect and mechanism of all-trans retinoic acid (ATRA) on leukemic cell line U937 cells with NPM1 mutation. Methods: Human acute myeloid leukemia cell line U937 was explored, NPM1 mutated (A type) plasmids were transfected into U937 to form stable clones A1 and A2, which were identified by Western blot and Co-immunoprecipitation. The cell proliferation was measured by methylthiazolyl tetrazolium bromide (MTT) ; cell cycle and cell apoptosis were explored by flow cytometric; cell colony formation was measured by microscope count, the molecular pathways related to cell proliferation were measured by Western blot. Results: ①The cell proliferations of mutant A1 and A2 were inhibited significantly by 52.6% and 35.8% (P<0.05) , respectively under ATRA exposure. ②The percentages of G(0)/G(1) stage of mutant A1 and A2 increased by 20.1% and 35.8%, respectively under ATRA exposure. ③All the U937 leukemic cells were inhibited under ATRA exposure; the decreased percentages of vector, wild-type and mutant NPM1 cells were 32.7%, 57.9% and 90.9% respectively. ④p-ERK decreased obviously after ATRA exposure in NPM1 mutated leukemic cells. ⑤More mutant NPM1 cells inclined to apoptosis under the exposure of ATRA and cytotoxic drugs than cytotoxic drugs alone, meanwhile more cells apoptosis occurred when ATRA was administrated after cytotoxic drugs exposure. Conclusions: ATRA could inhibit cell proliferation and colony formation, blocked the cell cycle in the G(0)/G(1) stage accompanied by the significant reduction of p-ERK in U937 leukemic cells with NPM1 mutation. Besides, ATRA could synergize with drugs to suppress the leukemic cells survival more effectively when ATRA was administered after the cytotoxic drugs exposure in U937 leukemic cells with NPM1 mutation.

Proteins of the Nucleolus of Dictyostelium discoideum: Nucleolar Compartmentalization, Targeting Sequences, Protein Translocations and Binding Partners

The nucleoli of Dictyostelium discoideum have a comparatively unique, non-canonical, localization adjacent to the inner nuclear membrane. The verified nucleolar proteins of this eukaryotic microbe are detailed while other potential proteins are introduced. Heat shock protein 32 (Hsp32), eukaryotic translation initiation factor 6 (eIF6), and tumour necrosis factor receptor-associated protein 1 (TRAP1) are essential for cell survival. NumA1, a breast cancer type 1 susceptibility protein-C Terminus domain-containing protein linked to cell cycle, functions in the regulation of nuclear number. The cell cycle checkpoint kinase 2 homologue forkhead-associated kinase A (FhkA) and BRG1-associated factor 60a homologue Snf12 are also discussed. While nucleoli appear homogeneous ultrastructurally, evidence for nucleolar subcompartments exists. Nucleolar localization sequences (NoLS) have been defined that target proteins to either the general nucleolar area or to a specific intranucleolar domain. Protein translocations during mitosis are protein-specific and support the multiple functions of the Dictyostelium nucleolus. To enrich the picture, binding partners of NumA1, the most well-characterized nucleolar protein, are examined: nucleolar Ca²⁺-binding protein 4a (CBP4a), nuclear puromycin-sensitive aminopeptidase A (PsaA) and Snf12. The role of Dictyostelium as a model for understanding the contribution of nucleolar proteins to various diseases and cellular stress is discussed throughout the review.

[Effects of NPM1 gene expression on acute myeloid leukemia cell lines and its mechanism]

目的

探讨NPM1基因表达对急性髓系白血病（AML）细胞系的影响及其机制。

方法

选取AML细胞系U937和HL-60细胞，转染NPM1质粒至细胞系构建稳定克隆，采用Western blot法鉴定高表达NPM1蛋白的单克隆细胞。MTT法检测细胞增殖活性，流式细胞术检测细胞周期分布和细胞凋亡率，显微镜下计数检测集落形成能力，Western blot法检测细胞周期相关信号通路蛋白表达，实时荧光定量PCR（RQ-PCR）法检测初诊AML患者骨髓单个核细胞NPM1基因表达水平。

结果

①U937和HL-60细胞中NPM1高表达组相对细胞增殖率与对照组相比，差异无统计学意义（4.68±1.28对3.89±0.81，3.34±0.37对2.68±0.29，P值均>0.05）。②U937和HL-60细胞中NPM1高表达组S期细胞比例均明显高于对照组[（50.22±3.42）%对（39.78±3.80）%，（59.01±3.27）%对（43.94±2.08）%，P值均<0.05]。③U937细胞NPM1高表达组和对照组相比具有更强的抗凋亡能力[（48.67±3.22）%和（68.77±10.21）%，P<0.05]和集落形成能力（772.7±24.0和652.3±16.5，P<0.05），而HL-60细胞相应的两组细胞上述能力均相似。④NPM1高表达组细胞中CDK4、Cyclin D1、Cyclin D2及Cyclin E表达明显高于对照组，而Cyclin D3表达明显低于对照组。⑤细胞遗传学预后良好组AML患者NPM1定量水平低于预后中等组。

结论

NPM1蛋白能够促进更多的细胞进入S期，增强抗凋亡和细胞集落形成能力。NPM1定量水平可能预示细胞遗传学的危险度。

Implication of B23/NPM1 in Viral Infections, Potential Uses of B23/NPM1 Inhibitors as Antiviral Therapy

BACKGROUND

B23/nucleophosmin (B23/NPM1) is an abundant multifunctional protein mainly located in the nucleolus but constantly shuttling between the nucleus and cytosol. As a consequence of its constitutive expression, intracellular dynamics and binding capacities, B23/NPM1 interacts with multiple cellular factors in different cellular compartments, but also with viral proteins from both DNA and RNA viruses. B23/NPM1 influences overall viral replication of viruses like HIV, HBV, HCV, HDV and HPV by playing functional roles in different stages of viral replication including nuclear import, viral genome transcription and assembly, as well as final particle formation. Of note, some virus modify the subcellular localization, stability and/or increases B23/NPM1 expression levels on target cells, probably to foster B23/NPM1 functions in their own replicative cycle.

RESULTS

This review summarizes current knowledge concerning the interaction of B23/NPM1 with several viral proteins during relevant human infections. The opportunities and challenges of targeting this well-conserved host protein as a potentially new broad antiviral treatment are discussed in detail. Importantly, although initially conceived to treat cancer, a handful of B23/NPM1 inhibitors are currently available to test on viral infection models.

CONCLUSION

As B23/NPM1 partakes in key steps of viral replication and some viral infections remain as unsolved medical needs, an appealing idea may be the expedite evaluation of B23/NPM1 inhibitors in viral infections. Furthermore, worth to be addressed is if the up-regulation of B23/NPM1 protein levels that follows persistent viral infections may be instrumental to the malignant transformation induced by virus like HBV and HCV.

Phosphoproteome Profiling Reveals Multifunctional Protein NPM1 as part of the Irradiation Response of Tumor Cells

To fight resistances to radiotherapy, the understanding of escape mechanisms of tumor cells is crucial. The aim of this study was to identify phosphoproteins that are regulated upon irradiation. The comparative analysis of the phosphoproteome before and after irradiation brought nucleophosmin (NPM1) into focus as a versatile phosphoprotein that has already been associated with tumorigenesis. We could show that knockdown of NPM1 significantly reduces tumor cell survival after irradiation. NPM1 is dephosphorylated stepwise within 1 hour after irradiation at two of its major phosphorylation sites: threonine-199 and threonine-234/237. This dephosphorylation is not the result of a fast cell cycle arrest, and we found a heterogenous intracellular distribution of NPM1 between the nucleoli, the nucleoplasm, and the cytoplasm after irradiation. We hypothesize that the dephosphorylation of NPM1 at threonine-199 and threonine-234/237 is part of the immediate response to irradiation and of importance for tumor cell survival. These findings could make NPM1 an attractive pharmaceutical target to radiosensitize tumor cells and improve the outcome of radiotherapy by inhibiting the pathways that help tumor cells to escape cell death after gamma irradiation.

Discovering proteins for chemoprevention and chemotherapy by curcumin in liver fluke infection-induced bile duct cancer

Modulation or prevention of protein changes during the cholangiocarcinoma (CCA) process induced by Opisthorchis viverrini (Ov) infection may become a key strategy for prevention and treatment of CCA. Monitoring of such changes could lead to discovery of protein targets for CCA treatment. Curcumin exerts anti-inflammatory and anti-CCA activities partly through its protein-modulatory ability. To support the potential use of curcumin and to discover novel target molecules for CCA treatment, we used a quantitative proteomic approach to investigate the effects of curcumin on protein changes in an Ov-induced CCA-harboring hamster model. Isobaric labelling and tandem mass spectrometry were used to compare the protein expression profiles of liver tissues from CCA hamsters with or without curcumin dietary supplementation. Among the dysregulated proteins, five were upregulated in liver tissues of CCA hamsters but markedly downregulated in the CCA hamsters supplemented with curcumin: S100A6, lumican, plastin-2, 14-3-3 zeta/delta and vimentin. Western blot and immunohistochemical analyses also showed similar expression patterns of these proteins in liver tissues of hamsters in the CCA and CCA + curcumin groups. Proteins such as clusterin and S100A10, involved in the NF-κB signaling pathway, an important signaling cascade involved in CCA genesis, were also upregulated in CCA hamsters and were then suppressed by curcumin treatment. Taken together, our results demonstrate the important changes in the proteome during the genesis of O. viverrini-induced CCA and provide an insight into the possible protein targets for prevention and treatment of this cancer.

Minimal/Measurable Residual Disease Monitoring in NPM1-Mutated Acute Myeloid Leukemia: A Clinical Viewpoint and Perspectives

Acute myeloid leukemia (AML) with NPM1 gene mutations is currently recognized as a distinct entity, due to its unique biological and clinical features. We summarize here the results of published studies investigating the clinical application of minimal/measurable residual disease (MRD) in patients with NPM1-mutated AML, receiving either intensive chemotherapy or hematopoietic stem cell transplantation. Several clinical trials have so far demonstrated a significant independent prognostic impact of molecular MRD monitoring in NPM1-mutated AML and, accordingly, the Consensus Document from the European Leukemia Net MRD Working Party has recently recommended that NPM1-mutated AML patients have MRD assessment at informative clinical timepoints during treatment and follow-up. However, several controversies remain, mainly with regard to the most clinically significant timepoints and the MRD thresholds to be considered, but also with respect to the optimal source to be analyzed, namely bone marrow or peripheral blood samples, and the correlation of MRD with other known prognostic indicators. Moreover, we discuss potential advantages, as well as drawbacks, of newer molecular technologies such as digital droplet PCR and next-generation sequencing in comparison to conventional RQ-PCR to quantify NPM1-mutated MRD. In conclusion, further prospective clinical trials are warranted to standardize MRD monitoring strategies and to optimize MRD-guided therapeutic interventions in NPM1-mutated AML patients.

Cysteine Proteases from V. cundinamarcensis (C. candamarcensis) Inhibit Melanoma Metastasis and Modulate Expression of Proteins Related to Proliferation, Migration and Differentiation

Previous studies showed that P1G10, a proteolytic fraction from Vasconcellea cundinamarcensis latex, reduced the tumor mass in animals bearing melanoma, increased in vitro DNA fragmentation and decreased cell adhesion. Here, we present some molecular and cellular events related to the antimetastatic effect induced by the CMS-2 fraction derived from P1G10 in metastatic melanoma B16-F10 and melanocyte Melan-a. Using difference gel electrophoresis and mass spectrometry, we identified four proteins overexpressed in tumor cells, all of them related to proliferation, survival, migration and cell invasion, that had their expression normalized upon treatment with CMS-2: nucleophosmin 1, heat shock protein 65, calcyclin binding protein and eukaryotic translation initiation factor 4H. In addition, some antioxidant and glycolytic enzymes show increased expression after exposure to CMS-2, along with an induction of melanogenesis (differentiation marker). The down regulation of cofilin 1, a protein involved in cell motility, may explain the inhibition of cell migration and dendritic-like outgrowth in B16-F10 and Melan-a, observed after CMS-2 treatment. Taken together, it is argued that CMS-2 modulates the expression of proteins related to metastatic development, driving the cell to a more differentiated-like state. These effects support the CMS-2 antimetastatic activity and place this fraction in the category of anticancer agent.

Mutant NPM1 Maintains the Leukemic State through HOX Expression

NPM1 is the most frequently mutated gene in cytogenetically normal acute myeloid leukemia (AML). In AML cells, NPM1 mutations result in abnormal cytoplasmic localization of the mutant protein (NPM1c); however, it is unknown whether NPM1c is required to maintain the leukemic state. Here, we show that loss of NPM1c from the cytoplasm, either through nuclear relocalization or targeted degradation, results in immediate downregulation of homeobox (HOX) genes followed by differentiation. Finally, we show that XPO1 inhibition relocalizes NPM1c to the nucleus, promotes differentiation of AML cells, and prolongs survival of Npm1-mutated leukemic mice. We describe an exquisite dependency of NPM1-mutant AML cells on NPM1c, providing the rationale for the use of nuclear export inhibitors in AML with mutated NPM1.

Oncogene c-fos and mutant R175H p53 regulate expression of Nucleophosmin implicating cancer manifestation

Nucleophosmin (NPM1) is a nucleolar protein that is frequently overexpressed in various types of solid tumors. NPM1 is involved in several cellular processes that might contribute significantly to the increased proliferation potential of cancers. Previous reports suggest that NPM1 expression is highly increased in response to mitogenic and oncogenic signals, the mechanisms of which have not been elucidated extensively. Using constructs incorporating different fragments of the NPM1 promoter upstream to a Luciferase reporter gene, we have identified the minimal promoter of NPM1 and candidate transcription factors regulating NPM1 promoter activity by luciferase reporter assays. We have validated the roles of a few candidate factors at the transcriptional and protein level by quantitative reverse transcriptase PCR, immunoblotting and immunohistochemistry, and explored the mechanism of regulation of NPM1 expression using immunoprecipitation and chromatin immunoprecipitation assays. We show here that the expression of NPM1 is regulated by transcription factor c-fos, a protein that is strongly activated by growth factor signals. In addition, mutant p53 (R175H) overexpression also enhances NPM1 expression possibly through c-myc and c-fos. Moreover, both c-fos and mutant p53 are overexpressed in oral tumor tissues that showed NPM1 overexpression. Collectively, our results suggest that c-fos and mutant p53 R175H positively regulate NPM1 expression, possibly in synergism, that might lead to oncogenic manifestation.

NPM1A in Plasma is a Potential Prognostic Biomarker in Acute Myeloid Leukemia

Objective

The aim of the study was to investigate whether nucleophosmin type A mutation (NPM1A) in plasma was associated with the prognosis of patients with acute myeloid leukemia (AML).

Methods

Plasma NPM1A levels were investigated in 80 AML patients, 22 patients with benign hematopathy and 12 healthy donors by qRT-PCR. Additionally, the relationship between NPM1A levels and clinic characteristics were evaluated by Chi-square test. Kaplan-Meier method was used to analyze overall survival (OS) and relapse-free survival (RFS), and univariate and multivariate analyses were performed with Cox proportional hazard model.

Results

Plasma levels of NPM1A in AML patients were significantly higher than those in benign hematopathy patients and healthy controls, respectively (both P<0.001). Additionally, high NPM1A level was significantly associated with higher WBC and platelet count (both, P<0.05). Moreover, survival analysis revealed that patients with high NPM1A levels had worse OS (P<0.001) and RFS (P<0.001). Multivariate analysis identified NPM1A as an independent prognostic predictor for AML (OS: HR=8.214, 95% CI: 2.974-22.688, P<0.001; RFS: HR=4.640, 95%CI: 1.825-11.795, P=0.001).

Conclusions

Results reveal that NPM1A in plasma could serve as an ideal tool for predicting the prognosis of patients with AML.

NPM1 alternative transcripts are upregulated in acute myeloid and lymphoblastic leukemia and their expression level affects patient outcome

Background

Expression of the NPM1 gene, encoding nucleophosmin, is upregulated in cancers. Although more than ten NPM1 transcripts are known, the reports were usually limited to one predominant transcript. In leukemia, the NPM1 expression has not been widely studied so far. In acute myeloid leukemia (AML), the mutational status of the gene seems to play a pivotal role in carcinogenesis. Therefore, the aim of the study was to quantify alternative NPM1 transcripts in two types of acute leukemia, AML and ALL (acute lymphoblastic leukemia).

Methods

Using droplet digital PCR, we analyzed the levels of three protein-coding NPM1 transcripts in 66 samples collected from AML and ALL patients and 16 control samples. Using RNA-seq, we detected 8 additional NPM1 transcripts, including non-coding splice variants with retained introns. For data analysis, Welch two sample t-test, Pearson’s correlation and Kaplan–Meier analysis were applied.

Results

The levels of the particular NPM1 transcripts were significantly different but highly correlated with each other in both leukemia and control samples. Transcript NPM1.1, encoding the longest protein (294 aa), had the highest level of accumulation and was one of the most abundant transcripts in the cell. Comparing to NPM1.1, the levels of the NPM1.2 and NPM1.3 transcripts, encoding a 265-aa and 259-aa proteins, were 30 and 3 times lower, respectively. All three NPM1 transcripts were proportionally upregulated in both types of leukemia compared to control samples. In AML, the levels of NPM1 transcripts decreased in complete remission and increased again with relapse of the disease. Low levels of NPM1.1 and NPM1.3 were associated with better prognosis. The contribution of non-coding transcripts to the total level of NPM1 gene seemed to be marginal, except for one short 5-end transcript accumulated at high levels in AML and control cells. Aberrant proportions of particular NPM1 splice variants could be linked to abnormal expression of genes encoding alternative splicing factors.

Conclusions

The levels of the studied NPM1 transcripts were different but highly correlated with each other. Their upregulation in AML and ALL, decrease after therapy and association with patient outcome suggests the involvement of elevated NPM1 expression in the acute leukemia pathogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1608-2) contains supplementary material, which is available to authorized users.

Poor prognosis of nucleophosmin overexpression in solid tumors: a meta-analysis

BACKGROUND

Nucleophosmin is a non-ribosomal nucleolar phosphoprotein that is found primarily in the nucleolus region of cell nucleus, plays multiple important roles in tumor processes. Accumulated previous studies have reported a potential value of NPM acted as a biomarker for prognosis in various solid tumors, but the results were more inconsistency. We performed this meta-analysis to precisely evaluate the prognostic significance of NPM in solid tumors.

METHODS

Clinical data were collected from a comprehensive literature search in PubMed, Web of Science, Embase, and China National Knowledge Infrastructure databases (up to October, 2017). A total of 11 studied with 997 patients were used to assess the association of NPM expression and patients' overall survival (OS). The hazard ratio (HR) or odds ratio (OR) with its 95% confidence intervals (CI) were calculated to estimate the effect.

RESULTS

The pooled results indicated that higher expression of NPM was observably correlated with poor OS in solid tumor (HR = 1.85, 95% CI: 1.44-2.38, P < 0.001). Furthermore, high expression of NPM was associated with some phenotypes of tumor aggressiveness, such as tumor stage (4 studies, III/IV vs. I/II, OR = 5.21, 95% CI: 2.72-9.56, P < 0.001), differentiation grade (poor vs. well/moderate, OR = 1.82, 95% CI: 1.01-3.27, P = 0.046).

CONCLUSION

This meta-analysis indicated that NPM may act as a valuable prognosis biomarker and a potential therapeutic target in human solid tumors.

FOXM1 contributes to treatment failure in acute myeloid leukemia

Acute myeloid leukemia (AML) patients with NPM1 mutations demonstrate a superior response to standard chemotherapy treatment. Our previous work has shown that these favorable outcomes are linked to the cytoplasmic relocalization and inactivation of FOXM1 driven by mutated NPM1. Here, we went on to confirm the important role of FOXM1 in increased chemoresistance in AML. A multiinstitution retrospective study was conducted to link FOXM1 expression to clinical outcomes in AML. We establish nuclear FOXM1 as an independent clinical predictor of chemotherapeutic resistance in intermediate-risk AML in a multivariate analysis incorporating standard clinicopathologic risk factors. Using colony assays, we show a dramatic decrease in colony size and numbers in AML cell lines with knockdown of FOXM1, suggesting an important role for FOXM1 in the clonogenic activity of AML cells. In order to further prove a potential role for FOXM1 in AML chemoresistance, we induced an FLT3-ITD-driven myeloid neoplasm in a FOXM1-overexpressing transgenic mouse model and demonstrated significantly higher residual disease after standard chemotherapy. This suggests that constitutive overexpression of FOXM1 in this model induces chemoresistance. Finally, we performed proof-of-principle experiments using a currently approved proteasome inhibitor, ixazomib, to target FOXM1 and demonstrated a therapeutic response in AML patient samples and animal models of AML that correlates with the suppression of FOXM1 and its transcriptional targets. Addition of low doses of ixazomib increases sensitization of AML cells to chemotherapy backbone drugs cytarabine and the hypomethylator 5-azacitidine. Our results underscore the importance of FOXM1 in AML progression and treatment, and they suggest that targeting it may have therapeutic benefit in combination with standard AML therapies.

MDM2- and FLT3-inhibitors in the treatment of FLT3-ITD acute myeloid leukemia, specificity and efficacy of NVP-HDM201 and midostaurin

Prognosis for FLT3-ITD positive acute myeloid leukemia with high allelic ratio (>0.5) is poor, particularly in relapse, refractory to or unfit for intensive treatment, thus highlighting an unmet need for novel therapeutic approaches. The combined use of compounds targeting both the mutated FLT3 receptor and cellular p53 inhibitors might be a promising treatment option for this poor risk leukemia subset. We therefore assessed MDM2 and FLT3 inhibitors as well as cytotoxic compounds used for conventional induction treatment as single agents and in combination for their ability to induce apoptosis and cell death in leukemic cells. Acute myeloid leukemia cells represented all major morphologic and molecular subtypes with normal karyotype, including FLT3-ITD (>0.5) and FLT3 wild type, NPM1 mutant and NPM1 wild type, as well as TP53 mutant and TP53 wild type cell lines. Acute myeloid leukemia cells with mutated or deleted TP53 were resistant to MDM2- and FLT3-inhibitors. FLT3-ITD positive TP53 wild type acute myeloid leukemia cells were significantly more susceptible to FLT3-inhibitors than FLT3-ITD negative TP53 wild type cells. The presence of a NPM1 mutation reduced the susceptibility of TP53 wild type acute myeloid leukemia cells to the MDM2 inhibitor NVP-HDM201. Moreover, the combined use of MDM2- and FLT3-inhibitors was superior to single agent treatment, and the combination of midostaurin and NVP-HDM201 was as specific and effective against FLT3-ITD positive TP53 wild type cells as the combination of midostaurin with conventional induction therapy. In summary, the combined use of the MDM2 inhibitor NVP-HDM201 and the FLT3 inhibitor midostaurin was a most effective and specific treatment to target TP53 and NPM1 wild type acute myeloid leukemia cells with high allelic FLT3-ITD ratio. These data suggest that the combined use of NVP-HDM201 and midostaurin might be a promising treatment option particularly in FLT3-ITD positive acute myeloid leukemia relapsed or refractory to conventional therapy.

Monitoring of nucleophosmin oligomerization in live cells

Oligomerization plays a crucial role in the function of nucleophosmin (NPM), an abundant nucleolar phosphoprotein. Two dual-color methods based on modern fluorescence confocal microscopy are applied for tracking NPM aggregates in live cells: cross-correlation Number and Brightness analysis (ccN&B) combined with pulsed interleaved excitation (PIE) and fluorescence-lifetime imaging microscopy (FLIM) utilizing resonance energy transfer (FRET). HEK-293T cells were transfected with mixture of plasmids designed for tagging with fluorescent proteins so that the cells express mixed population of NPM labeled either with eGFP or mRFP1. We observe joint oligomers formed from the fluorescently labeled NPM. Having validated the in vivo methods, we study an effect of substitutions in cysteine 21 (Cys21) of the NPM N-terminus on the oligomerization to demonstrate applicability of the methods. Inhibitory effect of mutations of the Cys21 to nonpolar Ala or to aromatic Phe on the oligomerization was reported in literature using in vitro semi-native electrophoresis. However, we do not detect any break-up of the joint NPM oligomers due to the Cys21 mutations in live cells. In vivo microscopy observations are supported by an in vitro method, the GFP-Trap immunoprecipitation assay. Our results therefore show importance of utilizing several methods for detection of biologically relevant protein aggregates. In vivo monitoring of the NPM oligomerization, a potential cancer therapy target, by the presented methods offers a new way to monitor effects of drugs that are tested as NPM oligomerization inhibitors directly in live cells.

Emerging evidence of the molecular landscape specific for hematogenous metastasis from gastric cancer

Gastric cancer (GC) is one of the most frequently diagnosed cancers in the world. Most GC patients are diagnosed when the cancer is in an advanced stage, and consequently, some develop metastatic lesions that generally cause cancer-related death. Metastasis establishment is affected by various conditions, such as tumor location, hemodynamics and organotropism. While digestive cancers may share a primary site, certain cases develop hematogenous metastasis with the absence of peritoneal metastasis, and vice versa. Numerous studies have revealed the clinicopathological risk factors for hematogenous metastasis from GC, such as vascular invasion, advanced age, differentiation, Borrmann type 1 or 2 and expansive growth. Recently, molecular mechanisms that contribute to metastatic site determination have been elucidated by advanced molecular biological techniques. Investigating the molecules that specifically participate in metastasis establishment in distinct secondary organs will lead to the development of novel biomarkers for patient stratification according to their metastatic risk and strategies for preventing and treating distinct metastases. We reviewed articles related to the molecular landscape of hematogenous metastasis from GC.

Antiproliferative effects of two gold(I)-N-heterocyclic carbene complexes in A2780 human ovarian cancer cells: a comparative proteomic study

Au(NHC) and Au(NHC)₂, i.e. a monocarbene gold(I) complex and the corresponding bis(carbene) complex, are two structurally related compounds, endowed with cytotoxic properties against several cancer cell lines. Herein, we explore the molecular and cellular mechanisms at the basis of their cytotoxicity in A2780 human ovarian cancer cells. Through a comparative proteomic analysis, we demonstrated that the number of modulated proteins is far larger in Au(NHC)₂-treated than in Au(NHC)-treated A2780 cells. Both gold compounds mainly affected proteins belonging to the following functional classes: protein synthesis, metabolism, cytoskeleton and stress response and chaperones. Particularly, Au(NHC)₂ gave rise to an evident upregulation of several glycolytic enzymes. Moreover, only Au(NHC)₂ triggered a net impairment of respiration and a metabolic shift towards glycolysis, suggesting that mitochondria are relevant cellular targets. We also found that both carbenes, similarly to the gold(I) compound auranofin, caused a strong inhibition of the seleno-enzyme thioredoxin reductase (TrxR). In conclusion, we highlighted that coordination of two carbene ligands to the same gold(I) center greatly enhances the antiproliferative effects of the resulting compound in comparison to the monocarbene derivative. Moreover, TrxR inhibition and metabolic impairment seem to play a major role in the Au(NHC)₂ cytotoxicity. Overall, these antiproliferative effects were also confirmed on other two human ovarian cancer cell lines (i.e. SKOV3 and IGROV1).

Treating hematological malignancies with drugs inhibiting ribosome biogenesis: when and why

It is well known that chemotherapy can cure only some cancers in advanced stage, mostly those with an intact p53 pathway. Hematological cancers such as lymphoma and certain forms of leukemia are paradigmatic examples of such scenario. Recent evidence indicates that the efficacy of many of the alkylating and intercalating agents, antimetabolites, topoisomerase, and kinase inhibitors used in cancer therapy is largely due to p53 stabilization and activation consequent to the inhibition of ribosome biogenesis. In this context, innovative drugs specifically hindering ribosome biogenesis showed preclinical activity and are currently in early clinical development in hematological malignancies. The mechanism of p53 stabilization after ribosome biogenesis inhibition is a multistep process, depending on specific factors that can be altered in tumor cells, which can affect the antitumor efficacy of ribosome biogenesis inhibitors (RiBi). In the present review, the basic mechanisms underlying the anticancer activity of RiBi are discussed based on the evidence deriving from available preclinical and clinical studies, with the purpose of defining when and why the treatment with drugs inhibiting ribosomal biogenesis could be highly effective in hematological malignancies.

Nucleolar Stress: hallmarks, sensing mechanism and diseases

The nucleolus is a prominent subnuclear compartment, where ribosome biosynthesis takes place. Recently, the nucleolus has gained attention for its novel role in the regulation of cellular stress. Nucleolar stress is emerging as a new concept, which is characterized by diverse cellular insult-induced abnormalities in nucleolar structure and function, ultimately leading to activation of p53 or other stress signaling pathways and alterations in cell behavior. Despite a number of comprehensive reviews on this concept, straightforward and clear-cut way criteria for a nucleolar stress state, regarding the factors that elicit this state, the morphological and functional alterations as well as the rationale for p53 activation are still missing. Based on literature of the past two decades, we herein summarize the evolution of the concept and provide hallmarks of nucleolar stress. Along with updated information and thorough discussion of existing confusions in the field, we pay particular attention to the current understanding of the sensing mechanisms, i.e., how stress is integrated by p53. In addition, we propose our own emphasis regarding the role of nucleolar protein NPM1 in the hallmarks of nucleolar stress and sensing mechanisms. Finally, the links of nucleolar stress to human diseases are briefly and selectively introduced.

Identification of Potential Anticancer Protein Targets in Cytotoxicity Mediated by Tropical Medicinal Fern Extracts

Background:

Medicinal fern species represent a potentially important source for both food and medicinal applications. Previously, two underutilized tropical fern species (Blechnum orientale and Phymatopteris triloba) were reported with cytotoxic activities against selected cancer cell lines. However, the exact mechanism remains elusive.

Objective:

In this paper, we reported the identification of six differentially expressed proteins isolated from cancer cells, following exposure to the cytotoxic fern extracts.

Materials and Methods:

The identities of these cancer proteins were determined by matrix-assisted laser desorption ionization time-of-flight protein sequencing.

Results:

The cancer proteins were identified as follows: elongation factor 1-γ, glyceraldehydes-3-phosphate dehydrogenase, heat shock protein 90-β, heterogeneous nuclear ribonucleoprotein-A2/B1, truncated nucleolar phosphoprotein B23, and tubulin-β chain. To the best of our knowledge, this paper represents the first time these cancer proteins are being reported, following exposure to the aforementioned cytotoxic fern extracts.

Conclusion:

It is hoped that further efforts in this direction could lead to the identification and development of target-specific chemotherapeutic agents.

SUMMARY

Cytotoxic fern extracts were tested in anti-cancer proteomic works.

Six differentially-expressed cancer proteins were identified.

Potential anti-cancer protein targets were reported.

Abbreviations used: EF: Elongation factor; HRP: Horseradish peroxidase; HSP: Heat shock protein; MALDI: Matrix-assisted laser desorption/ionization.

Using a panel of multiple tumor-associated antigens to enhance autoantibody detection for immunodiagnosis of gastric cancer

Autoantibodies against tumor-associated antigens (TAAs) are attractive non-invasive biomarkers for detection of cancer due to their inherently stable in serum. Serum autoantibodies against 9 TAAs from gastric cancer (GC) patients and healthy controls were measured by enzyme-linked immunosorbent assay (ELISA). A logistic regression model predicting the risk of being diagnosed with GC in the training cohort (n = 558) was generated and then validated in an independent cohort (n = 372). Area under the receiver operating characteristic curve (AUC) was used to assess the diagnostic performance. Finally, an optimal prediction model with 6 TAAs (p62, c-Myc, NPM1, 14-3-3ξ, MDM2 and p16) showed a great diagnostic performance of GC with AUC of 0.841 in the training cohort and 0.856 in the validation cohort. The proportion of subjects being correctly defined were 78.49% in the training cohort and 81.99% in the validation cohort. This prediction model could also differentiate early-stage (stage I-II) GC patients from healthy controls with sensitivity/specificity of 76.60%/72.34% and 80.56%/79.17% in the training and validation cohort, respectively, and the overall sensitivity/specificity for early-stage GC were 78.92%/74.70% when being combined with two cohorts. This prediction model presented no significant difference for the diagnostic accuracy between early-stage and late-stage (stage III - IV) GC patients. The model with 6 TAAs showed a high diagnostic performance for GC detection, particularly for early-stage GC. This study further supported the hypothesis that a customized array of multiple TAAs was able to enhance autoantibody detection in the immunodiagnosis of GC.

Pan-CDK inhibition augments cisplatin lethality in nasopharyngeal carcinoma cell lines and xenograft models

In addition to their canonical roles in regulating cell cycle transition and transcription, cyclin-dependent kinases (CDKs) have been shown to coordinate DNA damage response pathways, suggesting a rational pairing of CDK inhibitors with genotoxic chemotherapeutic agents in the treatment of human malignancies. Here, we report that roniciclib (BAY1000394), a potent pan-CDK inhibitor, displays promising anti-neoplastic activity as a single agent and potentiates cisplatin lethality in preclinical nasopharyngeal carcinoma (NPC) models. Proliferation of the NPC cell lines HONE-1, CNE-2, C666-1, and HK-1 was effectively curbed by roniciclib treatment, with IC₅₀ values between 11 and 38 nmol/L. These anticancer effects were mediated by pleiotropic mechanisms consistent with successful blockade of cell cycle CDKs 1, 2, 3, and 4 and transcriptional CDKs 7 and 9, ultimately resulting in arrest at G1/S and G2/M, downregulation of the transcriptional apparatus, and repression of anti-apoptotic proteins. Considerably enhanced tumor cell apoptosis was achieved following combined treatment with 10 nmol/L roniciclib and 2.0 μmol/L cisplatin; this combination therapy achieved a response over 250% greater than either drug alone. Although roniciclib chemosensitized NPC cells to cisplatin, it did not sensitize untransformed (NP69) cells. The administration of 0.5 mg/kg roniciclib to BALB/c xenograft mice was well tolerated and effectively restrained tumor growth comparable to treatment with 6 mg/kg cisplatin, whereas combining these two agents produced far greater tumor suppression than either of the monotherapies. In summary, these data demonstrate that roniciclib has strong anti-NPC activity and synergizes with cisplatin chemotherapy at clinically relevant doses, thus justifying further evaluation of this combinatorial approach in clinical settings.

Nasopharyngeal carcinoma (NPC) is an uncommon malignancy arising from the nasopharynx epithelium, and is endemic to east and southeast parts of Asia where they account for 70% of worldwide incidence. Researchers from the Cancer Science Institute of Singapore examined the anti-tumor effects of roniciclib—a small-molecule drug that blocks a family of enzymes known as cyclin-dependent kinases (CDKs) which are classically involved in cell cycle progression and transcription—in cell lines and mouse models of nasopharyngeal carcinoma. Because CDK/cyclin complexes have a putative role in DNA repair, roniciclib was combined with cisplatin, a DNA-damaging agent which is currently used in chemotherapy of NPC. The authors found that roniciclib had potent anti-NPC effects when given alone, whereas the combination of roniciclib and cisplatin proved to be highly synergistic and restrained tumor growth to a greater extent than either drugs given alone. Interestingly, roniciclib appeared to selectively enhance the anti-cancer effects of cisplatin in cancerous cells while this “chemo-sensitizing” phenomenon was not seen in non-cancerous cells, suggesting that giving both drugs together could improve the effectiveness of standard chemotherapy without incurring additional toxicities. These findings suggest that roniciclib should be evaluated clinically in patients with NPC.

Beyond cell-cell adhesion: Plakoglobin and the regulation of tumorigenesis and metastasis

Plakoglobin (also known as? -catenin) is a member of the Armadillo family of proteins and a paralog of β -catenin. Plakoglobin is a component of both the adherens junctions and desmosomes, and therefore plays a vital role in the regulation of cell-cell adhesion. Similar to β -catenin, plakoglobin is capable of participating in cell signaling in addition to its role in cell-cell adhesion. In this context, β -catenin has a well-documented oncogenic potential as a component of the Wnt signaling pathway. In contrast, while some studies have suggested a tumor promoting activity of plakoglobin in a cell/malignancy specific context, it generally acts as a tumor/metastasis suppressor. How plakoglobin acts as a growth/metastasis inhibitory protein has remained, until recently, unclear. Recent evidence suggests that plakoglobin may suppress tumorigenesis and metastasis by multiple mechanisms, including the suppression of oncogenic signaling, interactions with various proteins involved in tumorigenesis and metastasis, and the regulation of the expression of genes involved in these processes. This review is primarily focused on various mechanisms by which plakoglobin may inhibit tumorigenesis and metastasis.

Comparative and network-based proteomic analysis of low dose ethanol- and lipopolysaccharide-induced macrophages

Macrophages are specialized phagocytes that play an essential role in inflammation, immunity, and tissue repair. Profiling the global proteomic response of macrophages to microbial molecules such as bacterial lipopolysaccharide is key to understanding fundamental mechanisms of inflammatory disease. Ethanol is a widely abused substance that has complex effects on inflammation. Reports have indicated that ethanol can activate or inhibit the lipopolysaccharide receptor, Toll-like Receptor 4, in different settings, with important consequences for liver and neurologic inflammation, but the underlying mechanisms are poorly understood. To profile the sequential effect of low dose ethanol and lipopolysaccharide on macrophages, a gel-free proteomic technique was applied to RAW 264.7 macrophages. Five hundred four differentially expressed proteins were identified and quantified with high confidence using ≥ 5 peptide spectral matches. Among these, 319 proteins were shared across all treatment conditions, and 69 proteins were exclusively identified in ethanol-treated or lipopolysaccharide-stimulated cells. The interactive impact of ethanol and lipopolysaccharide on the macrophage proteome was evaluated using bioinformatics tools, enabling identification of differentially responsive proteins, protein interaction networks, disease- and function-based networks, canonical pathways, and upstream regulators. Five candidate protein coding genes (PGM2, ISYNA1, PARP1, and PSAP) were further validated by qRT-PCR that mostly related to glucose metabolism and fatty acid synthesis pathways. Taken together, this study describes for the first time at a systems level the interaction between ethanol and lipopolysaccharide in the proteomic programming of macrophages, and offers new mechanistic insights into the biology that may underlie the impact of ethanol on infectious and inflammatory disease in humans.

c-Myc targeted regulators of cell metabolism in a transgenic mouse model of papillary lung adenocarcinoma

c-Myc's role in pulmonary cancer metabolism is uncertain. We therefore investigated c-Myc activity in papillary lung adenocarcinomas (PLAC). Genomics revealed 90 significantly regulated genes (> 3-fold) coding for cell growth, DNA metabolism, RNA processing and ribosomal biogenesis and bioinformatics defined c-Myc binding sites (TFBS) at > 95% of up-regulated genes. EMSA assays at 33 novel TFBS evidenced DNA binding activity and ChIP-seq data retrieved from public repositories confirmed these to be c-Myc bound. Dual-luciferase gene reporter assays developed for RNA-Terminal-Phosphate-Cyclase-Like-1(RCL1), Ribosomal-Protein-SA(RPSA), Nucleophosmin/Nucleoplasmin-3(NPM3) and Hexokinase-1(HK1) confirmed c-Myc functional relevance and ChIP assays with HEK293T cells over-expressing ectopic c-Myc demonstrated enriched c-Myc occupancy at predicted TFBS for RCL1, NPM3, HK1 and RPSA. Note, c-Myc recruitment on chromatin was comparable to the positive controls CCND2 and CDK4. Computational analyses defined master regulators (MR), i.e. heterogeneous nuclear ribonucleoprotein A1, nucleolin, the apurinic/apyrimidinic endonuclease 1, triosephosphate-isomerase 1, folate transporter (SLC19A1) and nucleophosmin to influence activity of up to 90% of PLAC-regulated genes. Their expression was induced by 3-, 3-, 6-, 3-, 11- and 7-fold, respectively. STRING analysis confirmed protein-protein-interactions of regulated genes and Western immunoblotting of fatty acid synthase, serine hydroxyl-methyltransferase 1, arginine 1 and hexokinase 2 showed tumor specific induction. Published knock down studies confirmed these proteins to induce apoptosis by disrupting neoplastic lipogenesis, by endorsing uracil accumulation and by suppressing arginine metabolism and glucose-derived ribonucleotide biosynthesis. Finally, translational research demonstrated high expression of MR and of 47 PLAC up-regulated genes to be associated with poor survival in lung adenocarcinoma patients (HR 3.2 p < 0.001) thus, providing a rationale for molecular targeted therapies in PLACs.

Cancer upregulated gene 2 induces epithelial-mesenchymal transition of human lung cancer cells via TGF-β signaling

Cancer upregulated gene 2 (CUG2) enhances cell migration and invasion, but the underlying mechanism has not been revealed. Herein, CUG2 decreased the expression of E-cadherin and increased the expression of N-cadherin and vimentin, characteristics of the epithelial-mesenchymal transition (EMT). A CUG2 deletion mutant, lacking interaction with nucleophosmin 1 (NPM1), or suppression of NPM1 reduced wound healing and cell invasion, indicating that CUG2-mediated EMT requires NPM1. CUG2 enhanced activation of Smad2/3 and expression of Snail and Twist, while the CUG2 silence decreased these TGF-β signaling pathways, leading to suppression of EMT. NPM silence also inhibited the CUG2-induced TGF-β signaling. These results suggest that TGF-β signaling is involved in CUG2-induced EMT. Treatment with EW-7197, a novel inhibitor of TGF-β signaling, diminished CUG2-mediated EMT and inhibition of Akt, ERK, JNK, and p38 MAPK, non-canonical TGF-β signaling molecules, also decreased expression of Smad2/3, Snail and Twist, leading to inhibition of EMT. The results confirm that TGF-β signaling is essential for CUG2-mediated EMT. Interestingly, TGF-β enhanced CUG2 expression. We further found that both CUG2-induced TGF-β production and TGF-β-induced CUG2 up-regulation required a physical interaction between Sp1 and Smad2/3 in the CUG2 and TGF-β promoter, as demonstrated by a promoter reporter assay, immunoprecipitation, and ChIP assay. These results indicated close crosstalk between CUG2 and TGF-β. Conversely, suppression of CUG2 or NPM1 did not completely inhibit TGF-β-induced EMT, indicating that the effect of TGF-β on EMT is dominant over the effect of CUG2 on EMT. Collectively, our findings suggest that CUG2 induces the EMT via TGF-β signaling.

Long noncoding RNA HOTAIR mediates the estrogen-induced metastasis of endometrial cancer cells via the miR-646/NPM1 axis

LncRNA homeobox (HOX) transcript antisense intergenic RNA (HOTAIR) has been confirmed to be involved in the tumorigenic progression of endometrial carcinoma (EC). However, the molecular mechanisms of HOTAIR in EC are not fully elucidated. The expression of HOTAIR and miR-646 in human EC tissues was determined by qRT-PCR. The effect of miR-646 on EC cells was assessed by the cell viability, migration, and invasion using CCK-8 assays and transwell assays. RNA-binding protein immunoprecipitation assays and RNA pull-down assays were performed to explore the interaction between HOTAIR and miR-646. The regulation of miR-646 on nucleophosmin 1 (NPM1) was tested using luciferase reporter assays. MiR-646 expression was significantly decreased both in human EC tissues ( n = 23) and cell lines (Ishikawa and HEC-1-A) compared with the control. Moreover, miR-646 expression was negatively related to HOTAIR in human EC tissues ( n = 23). Our results also showed that miR-646 overexpression considerably attenuated the E2-promoted viability, migration, and invasion of Ishikawa and HEC-1-A cells in vitro. In addition, HOTAIR was confirmed to regulate the viability, migration, and invasion of EC cells through negative regulating miR-646. More importantly, we also demonstrated that NPM1 was the target of miR-646, and HOTAIR promoted NPM1 expression through interacting with miR-646 in EC cells. Taken together, our findings presented that HOTAIR could regulate NPM1 via interacting with miR-646, thereby governing the viability, migration, and invasion of EC cells.

[Renal cell carcinoma associated with Xp11 translocation involving the gene]

The paper describes a clinical case of the rare tumor renal cell carcinoma associated with Xp11 translocations involving the TFE3 gene in a 53-year-old male patient. It provides the detailed characteristics of current diagnostic techniques.

Role and targeting of anaplastic lymphoma kinase in cancer

Anaplastic lymphoma kinase (ALK) gene activation is involved in the carcinogenesis process of several human cancers such as anaplastic large cell lymphoma, lung cancer, inflammatory myofibroblastic tumors and neuroblastoma, as a consequence of fusion with other oncogenes (NPM, EML4, TIM, etc) or gene amplification, mutation or protein overexpression.

ALK is a transmembrane tyrosine kinase receptor that, upon ligand binding to its extracellular domain, undergoes dimerization and subsequent autophosphorylation of the intracellular kinase domain. When activated in cancer it represents a target for specific inhibitors, such as crizotinib, ceritinib, alectinib etc. which use has demonstrated significant effectiveness in ALK-positive patients, in particular ALK-positive non- small cell lung cancer.

Several mechanisms of resistance to these inhibitors have been described and new strategies are underway to overcome the limitations of current ALK inhibitors.

Nucleophosmin modulates the alleviation of atopic dermatitis caused by the marine-derived compound dihydroaustrasulfone alcohol

Atopic dermatitis (AD) is a chronic inflammatory skin disease, and its prevalence is increasing. AD usually elicits skin barrier dysfunction, dry skin and itching. As the mechanisms of AD remain unknown, there is an urgent need to find effective therapies. Because of the diversity and complexity of marine environments, the discovery of drugs from marine organisms as novel therapeutic agents for human diseases has seen renewed interest. Dihydroaustrasulfone alcohol (WA-25), the synthetic precursor of austrasulfone, which is a natural product isolated from a Formosan soft coral, has been shown to possess many therapeutic effects in our previous studies. However, the detailed mechanisms and therapeutic effects of WA-25 on AD are incompletely understood. We performed in vitro and in vivo studies to examine the effects of WA-25 on AD. We showed that WA-25 blocks inflammation and oxidative stress. Simultaneously, we also found that WA-25 reduces the AD scores and AD-induced transepidermal water loss (TEWL), scratching behavior, and alloknesis. WA-25 is more effective in cases of AD than are the drugs that are currently used clinically. Importantly, we also found that when nucleophosmin (NPM) was inhibited or when its expression was reduced, the anti-inflammatory and anti-AD effects of WA-25 were blocked. These data suggest that NPM plays dual roles in inflammation and AD. Overall, these results suggest that WA-25 is a potential anti-inflammatory and AD therapeutic agent that is modulated by NPM.

Nucleophosmin leukemogenic mutant activates Wnt signaling during zebrafish development

Nucleophosmin (NPM1) is a ubiquitous multifunctional phosphoprotein with both oncogenic and tumor suppressor functions. Mutations of the NPM1 gene are the most frequent genetic alterations in acute myeloid leukemia (AML) and result in the expression of a mutant protein with aberrant cytoplasmic localization, NPMc+. Although NPMc+ causes myeloproliferation and AML in animal models, its mechanism of action remains largely unknown. Here we report that NPMc+ activates canonical Wnt signaling during the early phases of zebrafish development and determines a Wnt-dependent increase in the number of progenitor cells during primitive hematopoiesis. Coherently, the canonical Wnt pathway is active in AML blasts bearing NPMc+ and depletion of the mutant protein in the patient derived OCI-AML3 cell line leads to a decrease in the levels of active β-catenin and of Wnt target genes. Our results reveal a novel function of NPMc+ and provide insight into the molecular pathogenesis of AML bearing NPM1 mutations.

Human Adenovirus Core Protein V Is Targeted by the Host SUMOylation Machinery To Limit Essential Viral Functions

Human adenoviruses (HAdV) are nonenveloped viruses containing a linear, double-stranded DNA genome surrounded by an icosahedral capsid. To allow proper viral replication, the genome is imported through the nuclear pore complex associated with viral core proteins. Until now, the role of these incoming virion proteins during the early phase of infection was poorly understood. The core protein V is speculated to bridge the core and the surrounding capsid. It binds the genome in a sequence-independent manner and localizes in the nucleus of infected cells, accumulating at nucleoli. Here, we show that protein V contains conserved SUMO conjugation motifs (SCMs). Mutation of these consensus motifs resulted in reduced SUMOylation of the protein; thus, protein V represents a novel target of the host SUMOylation machinery. To understand the role of protein V SUMO posttranslational modification during productive HAdV infection, we generated a replication-competent HAdV with SCM mutations within the protein V coding sequence. Phenotypic analyses revealed that these SCM mutations are beneficial for adenoviral replication. Blocking protein V SUMOylation at specific sites shifts the onset of viral DNA replication to earlier time points during infection and promotes viral gene expression. Simultaneously, the altered kinetics within the viral life cycle are accompanied by more efficient proteasomal degradation of host determinants and increased virus progeny production than that observed during wild-type infection. Taken together, our studies show that protein V SUMOylation reduces virus growth; hence, protein V SUMOylation represents an important novel aspect of the host antiviral strategy to limit virus replication and thereby points to potential intervention strategies.IMPORTANCE Many decades of research have revealed that HAdV structural proteins promote viral entry and mainly physical stability of the viral genome in the capsid. Our work over the last years showed that this concept needs expansion as the functions are more diverse. We showed that capsid protein VI regulates the antiviral response by modulation of the transcription factor Daxx during infection. Moreover, core protein VII interacts with SPOC1 restriction factor, which is beneficial for efficient viral gene expression. Here, we were able to show that core protein V also represents a novel substrate of the host SUMOylation machinery and contains several conserved SCMs; mutation of these consensus motifs reduced SUMOylation of the protein. Unexpectedly, we observed that introducing these mutations into HAdV promotes adenoviral replication. In conclusion, we offer novel insights into adenovirus core proteins and provide evidence that SUMOylation of HAdV factors regulates replication efficiency.

Phasing in on the cell cycle

Just like all matter, proteins can also switch between gas, liquid and solid phases. Protein phase transition has claimed the spotlight in recent years as a novel way of how cells compartmentalize and regulate biochemical reactions. Moreover, this discovery has provided a new framework for the study of membrane-less organelle biogenesis and protein aggregation in neurodegenerative disorders. We now argue that this framework could be useful in the study of cell cycle regulation and cancer. Based on our work on phase transitions of arginine-rich proteins in neurodegeneration, via combining mass spectroscopy with bioinformatics analyses, we found that also numerous proteins involved in the regulation of the cell cycle can undergo protein phase separation. Indeed, several proteins whose function affects the cell cycle or are associated with cancer, have been recently found to phase separate from the test tube to cells. Investigating the role of this process for cell cycle proteins and understanding its molecular underpinnings will provide pivotal insights into the biology of cell cycle progression and cancer.

mTOR transcriptionally and post-transcriptionally regulates Npm1 gene expression to contribute to enhanced proliferation in cells with Pten inactivation

The mammalian target of rapamycin (mTOR) plays essential roles in the regulation of growth-related processes such as protein synthesis, cell sizing and metabolism in both normal and pathological growing conditions. These functions of mTOR are thought to be largely a consequence of its cytoplasmic activity in regulating translation rate, but accumulating data highlight supplementary role(s) for this serine/threonine kinase within the nucleus. Indeed, the nuclear activities of mTOR are currently associated with the control of protein biosynthetic capacity through its ability to regulate the expression of gene products involved in the control of ribosomal biogenesis and proliferation. Using primary murine embryo fibroblasts (MEFs), we observed that cells with overactive mTOR signaling displayed higher abundance for the growth-associated Npm1 protein, in what represents a novel mechanism of Npm1 gene regulation. We show that Npm1 gene expression is dependent on mTOR as demonstrated by treatment of wild-type and Pten inactivated MEFs cultured with rapamycin or by transient transfections of small interfering RNA directed against mTOR. In accordance, the mTOR kinase localizes to the Npm1 promoter gene in vivo and it enhances the activity of a human NPM1-luciferase reporter gene providing an opportunity for direct control. Interestingly, rapamycin did not dislodge mTOR from the Npm1 promoter but rather strongly destabilized the Npm1 transcript by increasing its turnover. Using a prostate-specific Pten-deleted mouse model of cancer, Npm1 mRNA levels were found up-regulated and sensitive to rapamycin. Finally, we also showed that Npm1 is required to promote mTOR-dependent cell proliferation. We therefore proposed a model whereby mTOR is closely involved in the transcriptional and posttranscriptional regulation of Npm1 gene expression with implications in development and diseases including cancer.

Identification of a novel nucleophosmin-interaction motif in the tumor suppressor p14arf

The tumor suppressor p14arf interacts, in response to oncogenic signals, with the p53 E3-ubiquitin ligase HDM2, thereby resulting in p53 stabilization and activation. In addition, it also exerts tumor-suppressive functions in p53-independent contexts. The activities of p14arf are regulated by the nucleolar chaperone nucleophosmin (NPM1), which controls its levels and cellular localization. In acute myeloid leukemia with mutations in the NPM1 gene, mutated NPM1 aberrantly translocates in the cytosol carrying with itself p14arf that is subsequently degraded, thus impairing the p14arf-HDM2-p53 axis. In this work we investigated the complex between these two proteins by means of NMR and other techniques. We identified a novel NPM1-interacting motif in the C-terminal region of p14arf, which corresponds to its predicted nucleolar localization signal. This motif recognizes a specific region of the NPM1 N-terminal domain and, upon binding, the two proteins form soluble high molecular weight complexes. By NMR, we identified critical residues on both proteins involved in the interaction. Collectively, our data provide a structural framework to rationalize the overall assembly of the p14arf-NPM1 supramolecular complexes. A number of p14arf cancer-associated mutations cluster in this motif and their effect on the interaction with NPM1 was also analyzed.

Molecules that target nucleophosmin for cancer treatment: an update

Nucleophosmin is a highly and ubiquitously expressed protein, mainly localized in nucleoli but able to shuttle between nucleus and cytoplasm. Nucleophosmin plays crucial roles in ribosome maturation and export, centrosome duplication, cell cycle progression, histone assembly and response to a variety of stress stimuli. Much interest in this protein has arisen in the past ten years, since the discovery of heterozygous mutations in the terminal exon of the NPM1 gene, which are the most frequent genetic alteration in acute myeloid leukemia. Nucleophosmin is also frequently overexpressed in solid tumours and, in many cases, its overexpression correlates with mitotic index and metastatization. Therefore it is considered as a promising target for the treatment of both haematologic and solid malignancies. NPM1 targeting molecules may suppress different functions of the protein, interfere with its subcellular localization, with its oligomerization properties or drive its degradation. In the recent years, several such molecules have been described and here we review what is currently known about them, their interaction with nucleophosmin and the mechanistic basis of their toxicity. Collectively, these molecules exemplify a number of different strategies that can be adopted to target nucleophosmin and we summarize them at the end of the review.

The DNA damage response (DDR) is induced by the C9orf72 repeat expansion in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a rapidly progressing neurodegenerative disease affecting motor neurons. Hexanucleotide (GGGGCC) repeat expansions in a non-coding region of C9orf72 are the major cause of familial ALS and frontotemporal dementia (FTD) worldwide. The C9orf72 repeat expansion undergoes repeat-associated non-ATG (RAN) translation to produce five dipeptide repeat proteins (DRPs), including poly(GR) and poly(PR). Whilst it remains unclear how mutations in C9orf72 lead to neurodegeneration in ALS/FTD, dysfunction to the nucleolus and R loop formation are implicated as pathogenic mechanisms. These events can damage DNA and hence genome integrity. Cells activate the DNA damage response (DDR) with the aim of repairing this damage. However, if the damage cannot be repaired, apoptosis is triggered. In lumbar motor neurons from C9orf72-positive ALS patients, we demonstrate significant up-regulation of markers of the DDR compared to controls: phosphorylated histone 2AX (γ-H2AX), phosphorylated ataxia telangiectasia mutated (p-ATM), cleaved poly (ADP-Ribose) polymerase 1 (PARP-1) and tumour suppressor p53-binding protein (53BP1). Similarly, significant up-regulation of γ-H2AX and p-ATM was detected in neuronal cells expressing poly(GR)100 and poly(PR)100 compared to controls, revealing that DNA damage is triggered by the DRPs. Nucleophosmin (NPM1) is a histone chaperone induced during the DDR, which interacts with APE1 to enhance DNA repair. We also demonstrate that more NPM1 precipitates with APE1 in C9orf72 patients compared to controls. Furthermore, overexpression of NPM1 inhibits apoptosis in cells expressing poly(GR)100 and poly(PR)100. This study therefore demonstrates that DNA damage is activated by the C9orf72 repeat expansion in ALS.

DUSP3/VHR: A Druggable Dual Phosphatase for Human Diseases

Protein tyrosine kinases (PTK), discovered in the 1970s, have been considered master regulators of biological processes with high clinical significance as targets for human diseases. Their actions are countered by protein tyrosine phosphatases (PTP), enzymes yet underrepresented as drug targets because of the high homology of their catalytic domains and high charge of their catalytic pocket. This scenario is still worse for some PTP subclasses, for example, for the atypical dual-specificity phosphatases (ADUSPs), whose biological functions are not even completely known. In this sense, the present work focuses on the dual-specificity phosphatase 3 (DUSP3), also known as VH1-related phosphatase (VHR), an uncommon regulator of mitogen-activated protein kinase (MAPK) phosphorylation. DUSP3 expression and activities are suggestive of a tumor suppressor or tumor-promoting enzyme in different types of human cancers. Furthermore, DUSP3 has other biological functions involving immune response mediation, thrombosis, hemostasis, angiogenesis, and genomic stability that occur through either MAPK-dependent or MAPK-independent mechanisms. This broad spectrum of actions is likely due to the large substrate diversity and molecular mechanisms that are still under scrutiny. The growing advances in characterizing new DUSP3 substrates will allow the development of pharmacological inhibitors relevant for possible future clinical trials. This review covers all aspects of DUSP3, since its gene cloning and crystallographic structure resolution, in addition to its classical and novel substrates and the biological processes involved, followed by an update of what is currently known about the DUSP3/VHR-inhibiting compounds that might be considered potential drugs to treat human diseases.

Contribution of nucleophosmin overexpression to multidrug resistance in breast carcinoma

Multidrug resistance (MDR) is a serious obstacle in breast cancer patients which limits chemotherapeutic drugs application. Our previous study confirmed that overexpression of nucleophosmin (NPM) was closely related to MDR in methotrexate-resistant breast cancer cells (MCF-7/MTX), and NPM could be a potential therapeutic target for chemoresistance. In this work, we aim to investigate NPM-mediated resistance mechanism in breast carcinoma. The NPM level was strongly positive in breast carcinoma tissues compared with adjacent normal samples, which was associated with lymph node metastasis. We found abnormal expression of NPM activated PI3K/Akt pathway and affected downstream apoptosis factors. Then, NPM level was attenuated by RNA interfering technology, the sensitivity of MCF-7/MTX cells to methotrexate was obviously increased, factor level of mitochondria apoptosis pathway was significantly augmented, and Akt phosphorylation was inhibited. Furthermore, examination of Akt and NPM level demonstrated that Akt inhibitor MK-2206 sensitised resistant cells to methotrexate and induced MCF-7/MTX cell apoptosis by PI3K/Akt pathway and mitochondria apoptosis pathway. These suggested NPM-induced resistance and anti-apoptosis were required for Akt activity. NPM has a crucial function in MDR of breast cancer through influencing Akt activity and resistant cell apoptosis, and it could be expected to become a therapeutic target for chemoresistance in breast cancer.

Selective regulation of type II interferon-inducible genes by NPM1/nucleophosmin

Nucleophosmin (NPM1) is a multifunctional nucleolar protein. Here, we analyze the role of NPM1 in gene expression using our previous microarray data and find a relationship between NPM1 and interferon (IFN)-γ-inducible genes. We show that NPM1 selectively regulates the expression of a subset of IFN-γ-inducible genes and directly binds to two important transcription factors in the type II IFN pathway: signal transducer and activator of transcription 1 and interferon regulatory factor 1 (IRF1). Furthermore, NPM1 is found to regulate the IFN-γ-inducible promoter activity of major histocompatibility complex class II transactivator (CIITA), and mutation of the IRF1-binding site on the CIITA promoter abolishes the effect of NPM1. Our results suggest a novel mechanism for IFN-γ-mediated gene expression by NPM1.