Overexpression of DR-nm23, a protein encoded by a member of the nm23 gene family, inhibits granulocyte differentiation and induces apoptosis in 32Dc13 myeloid cells

Therapeutic Targeting of Non-oncogene Dependencies in High-risk Neuroblastoma

PURPOSE

Neuroblastoma is a pediatric malignancy of the sympathetic nervous system with diverse clinical behaviors. Genomic amplification of MYCN oncogene has been shown to drive neuroblastoma pathogenesis and correlate with aggressive disease, but the survival rates for those high-risk tumors carrying no MYCN amplification remain equally dismal. The paucity of mutations and molecular heterogeneity has hindered the development of targeted therapies for most advanced neuroblastomas. We use an alternative method to identify potential drugs that target nononcogene dependencies in high-risk neuroblastoma.

EXPERIMENTAL DESIGN

By using a gene expression-based integrative approach, we identified prognostic signatures and potentially effective single agents and drug combinations for high-risk neuroblastoma.

RESULTS

Among these predictions, we validated in vitro efficacies of some investigational and marketed drugs, of which niclosamide, an anthelmintic drug approved by the FDA, was further investigated in vivo. We also quantified the proteomic changes during niclosamide treatment to pinpoint nucleoside diphosphate kinase 3 (NME3) downregulation as a potential mechanism for its antitumor activity.

CONCLUSIONS

Our results establish a gene expression-based strategy to interrogate cancer biology and inform drug discovery and repositioning for high-risk neuroblastoma.

Potential role of nucleoside diphosphate kinase in myricetin-induced selective apoptosis in colon cancer HCT-15 cells

The flavonoid myricetin (MYR) is derived from vegetables and fruits. It has been shown to exert anti-cancer effects in various cell lines; however, the exact mechanism underlying these effects is yet to be elucidated. In this study, we evaluated the anti-cancer effects induced by MYR treatment in colon cancer HCT-15 cells. To detect cell proliferation, we conducted MTT assay and real time-cell electronic sensing (RT-CES). We next performed comet assay and Annexin V and PI staining to detect cellular apoptotic features. After that, we conducted two-dimensional electrophoresis (2-DE) analysis to identify apoptotic proteins. The results of this analysis revealed that eight spots were differentially expressed. Among the spots, we selected nucleoside diphosphate kinase (NDPK) for further investigation, as it has been shown to regulate cancer cell apoptosis and metastasis. After that, we conducted realtime-PCR and western blot to detect the expression of NDPK mRNA and protein and wound-healing assay to detect cell migration and invasion. Finally, we performed NDPK siRNA transfection study and the results showed that NDPK knockdown inhibited apoptosis. Based on these collective results, we suggest that MYR induces apoptosis in human colon cancer HCT-15 cells selectively by increasing the expression of NDPK and other caspase-regulated apoptosis proteins.

Nucleoside Diphosphate Kinase-3 (NME3) Enhances TLR5-Induced NFB Activation

Bacterial flagellin is a potent activator of NFκB signaling, inflammation, and host innate immunity, and recent data indicate that flagellin represents a novel antitumor ligand acting through toll-like receptor 5 (TLR5) and the NFκB pathway to induce host immunity and aid in the clearance of tumor xenografts. To identify innate signaling components of TLR5 responsible for these antitumor effects, a loss-of-function high-throughput screen was employed utilizing carcinoma cells expressing a dynamic NFκB bioluminescent reporter stimulated by Salmonella typhimurium expressing flagellin. A live cell screen of a siRNA library targeting 691 known and predicted human kinases to identify novel tumor cell modulators of TLR5-induced NFκB activation uncovered several interesting positive and negative candidate regulators not previously recognized, including nucleoside diphosphate kinase 3 (NME3), characterized as an enhancer of signaling responses to flagellin. Targeted knockdown and overexpression assays confirmed the regulatory contribution of NME3 to TLR5-mediated NFκB signaling, mechanistically downstream of MyD88. Furthermore, Kaplan-Meier survival analysis showed that NME3 expression correlated highly with TLR5 expression in breast, lung, ovarian, and gastric cancers, and furthermore, high-level expression of NME3 increased overall survival for patients with breast, lung, and ovarian cancer, but the opposite in gastric cancer. Together, these data identify a previously unrecognized proinflammatory role for NME3 in signaling downstream of TLR5 that may potentiate cancer immunotherapies.Implications: Proinflammatory signaling mediated by innate immunity engagement of flagellin-activated TLR5 in tumor cells results in antitumor effects through NME3 kinase, a positive downstream regulator of flagellin-mediated NFκB signaling, enhancing survival for several human cancers. Mol Cancer Res; 16(6); 986-99. ©2018 AACR.

Characterization of Functional Domains in NME1L Regulation of NF-κB Signaling

NME1 is a well-known metastasis suppressor which has been reported to be downregulated in some highly aggressive cancer cells. Although most studies have focused on NME1, the NME1 gene also encodes the protein (NME1L) containing N-terminal 25 extra amino acids by alternative splicing. According to previous studies, NME1L has potent anti-metastatic activity, in comparison with NME1, by interacting with IKKβ and regulating its activity. In the present study, we tried to define the role of the N-terminal 25 amino acids of NME1L in NF-κB activation signaling. Unfortunately, the sequence itself did not interact with IKKβ, suggesting that it may be not enough to constitute the functional structure. Further construction of NME1L fragments and biochemical analysis revealed that N-terminal 84 residues constitute minimal structure for homodimerization, IKKβ interaction and regulation of NF-κB signaling. The inhibitory effect of the fragment on cancer cell migration and NF-κB-stimulated gene expression was equivalent to that of whole NME1L. The data suggest that the N-terminal 84 residues may be a core region for the anti-metastatic activity of NME1L. Based on this result, further structural analysis of the binding between NME1L and IKKβ may help in understanding the anti-metastatic activity of NME1L and provide direction to NME1L and IKKβ-related anti-cancer drug design.

Effect of DR-nm23 overexpression on biological characteristics of human colorectal carcinoma SW620 cells

AIM: To investigate the effect of DR-nm23 overexpression on biological characteristics of human colorectal carcinoma SW620 cells.

METHODS: SW620 cells were divided into three groups: non-endogenous expression (SW620) group, mock control (SW620/mock) group, and recombinant lentiviral expression vector pGC-FU-DR-nm23-GFP transfected (SW620/DR-nm23) group. Both in vitro cell experiments and in vivo xenograft tumor model assay were carried out to investigate the role of DR-nm23 in regulation of colorectal cancer cell proliferation, movement, invasion and metastasis.

RESULTS: Induced overexpression of DR-nm23 in SW620 cells via lentiviral infection resulted in significant inhibition of cell proliferation as revealed by cell growth curve (F = 15.657, P = 0.002) and clonogenic assay (F = 45.476, P = 0.003) in vitro. Meanwhile, Transwell assay showed that the numbers of cells that passed the membrane in the SW620/DR-nm23 group, SW620/mock group and SW620 group were 14.00 ± 1.85, 18.00 ± 2.01, and 17.00 ± 1.98, respectively, indicating that the migration ability was also significantly impaired in the SW620/DR-nm23 group (F = 10.746, P = 0.006). There was no significant difference in the three groups in Boyden chamber assay. Besides, the growth rate (F = 5.579, P = 0.008) and liver metastasis rate of the SW620/DR-nm23 group were significantly reduced as compared with those of the SW620 or SW620/mock group in vivo.

CONCLUSION: Overexpression of DR-nm23 may inhibit the invasive and metastatic capabilities of colorectal carcinoma SW620 cells. Thus, expression status of DR-nm23 may act as a potential prognostic factor in patients with colorectal cancer.

Distal Partial Trisomy 15q26 and Partial Monosomy 16p13.3 in a 36-Year-Old Male with Clinical Features of Both Chromosomal Abnormalities

We report a 36-year-old Caucasian male identified with distal partial trisomy 15q and partial monosomy 16p from an unbalanced chromosome translocation detected by microarray and FISH analysis. He had a history of developmental delay and intellectual disability, chronic anemia, tall and slender stature, thoracic scoliosis and lumbar lordosis, and dysmorphic features. The distal partial trisomy 15q included the insulin-like growth factor 1 receptor gene involved with growth, while genes in the distal partial monosomy 16p region are involved with alpha hemoglobin production, intellectual disability, dysmorphic features, and acromegaly. The chromosome derivative found in our patient contains genes known to play a role in his phenotype.

Hepatocyte Turnover in Chronic HCV-Induced Liver Injury and Cirrhosis

Chronic hepatitis C virus (HCV) infection may eventually lead to progressive liver fibrosis and cirrhosis through a complex, multistep process involving hepatocyte death and regeneration. Despite common pathogenetic pathways present in all forms of liver cirrhosis irrespective of etiology, hepatocyte turnover and related molecular events in HCV-induced cirrhosis are increasingly being distinguished from even "similar" causes, such as hepatitis B virus- (HBV-) related cirrhosis. New insights in HCV-induced hepatocellular injury, differential gene expression, and regenerative pathways have recently revealed a different pattern of progression to irreversible parenchymal liver damage. A shift to the significant role of the host immune response rather than the direct effect of HCV on hepatocytes and the imbalance between antiapoptotic and proapoptotic signals have been investigated in several studies but need to be further elucidated. The present review aims to comprehensively summarize the current evidence on HCV-induced hepatocellular turnover with a view to outline the significant trends of ongoing research.

NDK-1, the homolog of NM23-H1/H2 regulates cell migration and apoptotic engulfment in C. elegans

Abnormal regulation of cell migration and altered rearrangement of cytoskeleton are characteristic of metastatic cells. The first described suppressor of metastatic processes is NM23-H1, which displays NDPK (nucleoside-diphosphate kinase) activity. To better understand the role of nm23 genes in cell migration, we investigated the function of NDK-1, the sole Caenorhabditis elegans homolog of group I NDPKs in distal tip cell (DTC) migration. Dorsal phase of DTC migration is regulated by integrin mediated signaling. We find that ndk-1 loss of function mutants show defects in this phase. Epistasis analysis using mutants of the α-integrin ina-1 and the downstream functioning motility-promoting signaling module (referred to as CED-10 pathway) placed NDK-1 downstream of CED-10/Rac. As DTC migration and engulfment of apoptotic corpses are analogous processes, both partially regulated by the CED-10 pathway, we investigated defects of apoptosis in ndk-1 mutants. Embryos and germ cells defective for NDK-1 showed an accumulation of apoptotic cell corpses. Furthermore, NDK-1::GFP is expressed in gonadal sheath cells, specialized cells for engulfment and clearence of apoptotic corpses in germ line, which indicates a role for NDK-1 in apoptotic corpse removal. In addition to the CED-10 pathway, engulfment in the worm is also mediated by the CED-1 pathway. abl-1/Abl and abi-1/Abi, which function in parallel to both CED-10/CED-1 pathways, also regulate engulfment and DTC migration. ndk-1(-);abi-1(-) double mutant embryos display an additive phenotype (e. g. enhanced number of apoptotic corpses) which suggests that ndk-1 acts in parallel to abi-1. Corpse number in ndk-1(-);ced-10(-) double mutants, however, is similar to ced-10(-) single mutants, suggesting that ndk-1 acts downstream of ced-10 during engulfment. In addition, NDK-1 shows a genetic interaction with DYN-1/dynamin, a downstream component of the CED-1 pathway. In summary, we propose that NDK-1/NDPK might represent a converging point of CED-10 and CED-1 pathways in the process of cytoskeleton rearrangement.

A novel phenotypic dissimilarity method for image-based high-throughput screens

Background

Discovering functional relationships of genes through cell-based phenotyping has become an important approach in functional genomics. High-throughput imaging offers the ability to quantitatively assess complex phenotypes after perturbation by RNA interference (RNAi). Such image-based high-throughput RNAi screening studies have facilitated the discovery of novel components of gene networks and their interactions. Images generated by automated microscopy are typically analyzed by extracting quantitative features of individual cells, resulting in large multidimensional data sets. Robust and sensitive methods to interpret these data sets and to derive biologically relevant information in a high-throughput and unbiased manner remain to be developed.

Results

Here we propose a new analysis method, PhenoDissim, which computes the phenotypic dissimilarity between cell populations via Support Vector Machine classification and cross validation. Applying this method to a kinome RNAi screening data set, we demonstrate that the proposed method shows a good replicate reproducibility, separation of controls and clustering quality, and we are able to identify siRNA phenotypes and discover potential functional links between genes.

Conclusions

PhenoDissim is a novel analysis method for image-based high-throughput screen, relying on two parameters which can be automatically optimized without a priori knowledge. PhenoDissim is freely available as an R package.

Structure of Nm23-H1 under oxidative conditions

Nm23-H1/NDPK-A, a tumour metastasis suppressor, is a multifunctional housekeeping enzyme with nucleoside diphosphate kinase activity. Hexameric Nm23-H1 is required for suppression of tumour metastasis and it is dissociated into dimers under oxidative conditions. Here, the crystal structure of oxidized Nm23-H1 is presented. It reveals the formation of an intramolecular disulfide bond between Cys4 and Cys145 that triggers a large conformational change that destabilizes the hexameric state. The dependence of the dissociation dynamics on the H2O2 concentration was determined using hydrogen/deuterium-exchange experiments. The quaternary conformational change provides a suitable environment for the oxidation of Cys109 to sulfonic acid, as demonstrated by peptide sequencing using nanoUPLC-ESI-q-TOF tandem MS. From these and other data, it is proposed that the molecular and cellular functions of Nm23-H1 are regulated by a series of oxidative modifications coupled to its oligomeric states and that the modified cysteines are resolvable by NADPH-dependent reduction systems. These findings broaden the understanding of the complicated enzyme-regulatory mechanisms that operate under oxidative conditions.

An Integrated Bioinformatics and Computational Biology Approach Identifies New BH3-Only Protein Candidates

In this study, we utilized an integrated bioinformatics and computational biology approach in search of new BH3-only proteins belonging to the BCL2 family of apoptotic regulators. The BH3 (BCL2 homology 3) domain mediates specific binding interactions among various BCL2 family members. It is composed of an amphipathic α-helical region of approximately 13 residues that has only a few amino acids that are highly conserved across all members. Using a generalized motif, we performed a genome-wide search for novel BH3-containing proteins in the NCBI Consensus Coding Sequence (CCDS) database. In addition to known pro-apoptotic BH3-only proteins, 197 proteins were recovered that satisfied the search criteria. These were categorized according to α-helical content and predictive binding to BCL-xL (encoded by BCL2L1) and MCL-1, two representative anti-apoptotic BCL2 family members, using position-specific scoring matrix models. Notably, the list is enriched for proteins associated with autophagy as well as a broad spectrum of cellular stress responses such as endoplasmic reticulum stress, oxidative stress, antiviral defense, and the DNA damage response. Several potential novel BH3-containing proteins are highlighted. In particular, the analysis strongly suggests that the apoptosis inhibitor and DNA damage response regulator, AVEN, which was originally isolated as a BCL-xL-interacting protein, is a functional BH3-only protein representing a distinct subclass of BCL2 family members.

Pro-oncogenic potential of NM23-H2 in hepatocellular carcinoma

NM23 is a family of structurally and functionally conserved proteins known as nucleoside diphosphate kinases (NDPK). There is abundant mRNA expression of NM23-H1, NM23-H2, or a read through transcript (NM23-LV) in the primary sites of hepatocellular carcinoma (HCC). Although the NM23-H1 protein is implicated as a metastasis suppressor, the role of NM23-H2 appears to be less understood. Thus, the aim of this study was to examine whether NM23-H2 is associated with hepatocarcinogenesis. The level of NM23-H2 expression in tumor tissues and the surrounding matrix appeared to be independent of etiology and tumor differentiation. Its subcellular localization was confined to mainly the cytoplasm and to a lesser extent in the nucleus. Ectopic expression of NM23-H2 in NIH3T3 fibroblasts and HLK3 hepatocytes showed a transformed morphology, enhanced focus formation, and allowed anchorage-independent growth. Finally, NIH3T3 fibroblasts and HLK3 hepatocytes stably expressing NM23-H2 produced tumors in athymic mice and showed c-Myc over-expression. In addition, NF-κB and cyclin D1 expression were also increased by NM23-H2. Lentiviral delivery of NM23-H2 shRNA inhibited tumor growth of xenotransplanted tumors produced from HLK3 cells stably expressing NM23-H2. Collectively, these results indicate that NM23-H2 may be pro-oncogenic in hepatocarcinogenesis.

Functional modulation of the metastatic suppressor Nm23-H1 by oncogenic viruses

Evidence over the last two decades from a number of disciplines has solidified some fundamental concepts in metastasis, a major contributor to cancer associated deaths. However, significant advances have been made in controlling this critical cellular process by focusing on targeted therapy. A key set of factors associated with this invasive phenotype is the nm23 family of over twenty metastasis-associated genes. Among the eight known isoforms, Nm23-H1 is the most studied potential anti-metastatic factor associated with human cancers. Importantly, a growing body of work has clearly suggested a critical role for Nm23-H1 in limiting tumor cell motility and progression induced by several tumor viruses, including Epstein-Barr virus (EBV), Kaposi's sarcoma associated herpes virus (KSHV) and human papilloma virus (HPV). A more in depth understanding of the interactions between tumor viruses encoded antigens and Nm23-H1 will facilitate the elucidation of underlying mechanism(s) which contribute to virus-associated cancers. Here, we review recent studies to explore the molecular links between human oncogenic viruses and progression of metastasis, in particular the deregulation of Nm23-H1 mediated suppression.

Construction of a lentiviral vector carrying the DR-nm23 gene and its stable expression in colorectal carcinoma SW620 cells

AIM: To construct a lentiviral vector carrying the DR-nm23 gene and to establish a human colorectal carcinoma cell line SW620 stably expressing this gene.

METHODS: Endogenous expression of the DR-nm23 gene in colorectal carcinoma cell lines was investigated by RT-PCR. The DR-nm23 cDNA was cloned into the lentiviral expression vector pGC-FU. Recombinant lentiviruses were produced by 293T cells following the co-transfection of pGC-FU-DR-nm23-GFP and packaging plasmids. Lentivirus titer was determined by serial dilution method. The supernatants of virus-producing cells containing DR-nm23 and GFP genes were used to transfect SW620 cells. GFP fluorescence was detected by fluorescent microscopy. The expression of DR-nm23 protein in SW620 cells was detected by Western blot.

RESULTS: The recombinant lentiviral vector pGC-FU-DR-nm23-GFP was successfully constructed, and the sequence of the DR-nm23 gene in the vector was identical to those recorded in NCBI (NM_002510). The recombinant lentiviral plasmid could effective1y transfect 293T cells, with a lentivirus titer of 2E+9 TU/mL. The supernatants of lentivirus could effectively infect SW620 cells. Abundant green fluorescence was observed by fluorescent microscopy, and more than 85% of SW620 cells stably and highly expressed the target gene.

CONCLUSION: A recombinant lentiviral vector carrying the DR-nm23 gene (pGC-FU-DR-nm23-GFP) has been constructed successfully, and a SW620 subline stably expressing the DR-nm23 gene has been successfully generated.

Metastasis suppressors in human benign prostate, intraepithelial neoplasia, and invasive cancer: their prospects as therapeutic agents

Despite advances in diagnosis and treatment of prostate cancer, development of metastases remains a major clinical challenge. Research efforts are dedicated to overcome this problem by understanding the molecular basis of the transition from benign cells to prostatic intraepithelial neoplasia (PIN), localized carcinoma, and metastatic cancer. Identification of proteins that inhibit dissemination of cancer cells will provide new perspectives to define novel therapeutics. Development of antimetastatic drugs that trigger or mimic the effect of metastasis suppressors represents new therapeutic approaches to improve patient survival. This review focuses on different biochemical and cellular functions of metastasis suppressors known to play a role in prostate carcinogenesis and progression. Ten putative metastasis suppressors implicated in prostate cancer are discussed. CD44s is decreased in both PIN and cancer; Drg-1, E-cadherin, KAI-1, RKIP, and SSeCKS show similar expression between benign epithelia and PIN, but are downregulated in invasive cancer; whereas, maspin, MKK4, Nm23 and PTEN are upregulated in PIN and downregulated in cancer. Moreover, the potential role of microRNA in prostate cancer progression, the understanding of the cellular distribution and localization of metastasis suppressors, their mechanism of action, their effect on prostate invasion and metastasis, and their potential use as therapeutics are addressed.

Ebselen is a potent non-competitive inhibitor of extracellular nucleoside diphosphokinase

Nucleoside di- and triphosphates and adenosine regulate several components of the mucocilairy clearance process (MCC) that protects the lung against infections, via activation of epithelial purinergic receptors. However, assessing the contribution of individual nucleotides to MCC functions remains difficult due to the complexity of the mechanisms of nucleotide release and metabolism. Enzymatic activities involved in the metabolism of extracellular nucleotides include ecto-ATPases and secreted nucleoside diphosphokinase (NDPK) and adenyl kinase, but potent and selective inhibitors of these activities are sparse. In the present study, we discovered that ebselen markedly reduced NDPK activity while having negligible effect on ecto-ATPase and adenyl kinase activities. Addition of radiotracer [γ(32)P]ATP to human bronchial epithelial (HBE) cells resulted in rapid and robust accumulation of [(32)P]-inorganic phosphate ((32)Pi). Inclusion of UDP in the incubation medium resulted in conversion of [γ(32)P]ATP to [(32)P]UTP, while inclusion of AMP resulted in conversion of [γ(32)P]ATP to [(32)P]ADP. Ebselen markedly reduced [(32)P]UTP formation but displayed negligible effect on (32)Pi or [(32)P]ADP accumulations. Incubation of HBE cells with unlabeled UTP and ADP resulted in robust ebselen-sensitive formation of ATP (IC(50) = 6.9 ± 2 μM). This NDPK activity was largely recovered in HBE cell secretions and supernatants from lung epithelial A549 cells. Kinetic analysis of NDPK activity indicated that ebselen reduced the V(max) of the reaction (K(i) = 7.6 ± 3 μM), having negligible effect on K(M) values. Our study demonstrates that ebselen is a potent non-competitive inhibitor of extracellular NDPK.

Proteomics of AML1/ETO Target Proteins: AML1–ETO Targets a C/EBP–NM23 Pathway

Introduction

The rational design of targeted therapies for acute myeloid leukemia (AML) requires the discovery of novel protein pathways in the systems biology of a specific AML subtype. We have shown that in the AML subtype with translocation t(8;21), the leukemic fusion protein AML1–ETO inhibits the function of transcription factors PU.1 and C/EBPα via direct protein–protein interaction. In addition, recently using proteomics, we have also shown that the AML subtypes differ in their proteome, interactome, and post-translational modifications.

Methods

We, therefore, hypothesized that the systematic identification of target proteins of AML1–ETO on a global proteome-wide level will lead to novel insights into the systems biology of t(8;21) AML on a post-genomic functional level. Thus, 6 h after inducible expression of AML1–ETO, protein expression changes were identified by two-dimensional gel electrophoresis and subsequent mass spectrometry analysis.

Results

Twenty-eight target proteins of AML1–ETO including prohibitin, NM23, HSP27, and Annexin1 were identified by MALDI-TOF mass spectrometry. AML1–ETO upregulated the differentiation inhibitory factor NM23 protein expression after 6 h, and the NM23 mRNA expression was also elevated in t(8;21) AML patient samples in comparison with normal bone marrow. AML1–ETO inhibited the ability of C/EBP transcription factors to downregulate the NM23 promoter. These data suggest a model in which AML1–ETO inhibits the C/EBP-induced downregulation of the NM23 promoter and thereby increases the protein level of differentiation inhibitory factor NM23.

Conclusions

Proteomic pathway discovery can identify novel functional pathways in AML, such as the AML1–ETO–C/EBP–NM23 pathway, as the main step towards a systems biology and therapy of AML.

Significance of DR-nm23 protein expression in colorectal carcinoma

AIM: To investigate the relationship between the expression of DR-nm23 protein and the carcinogenesis, progression and metastasis of colorectal carcinoma.

METHODS: Ninety-eight colorectal carcinoma specimens, 57 adenoma specimens and 42 normal colorectal tissue specimens were examined by immunohistochemistry using the streptavidin-peroxidase method. The correlation of DR-nm23 protein expression with the carcinogenesis, progression, lymph node metastasis, histological type and differentiation grade of colorectal carcinoma was then analyzed.

RESULTS: The positive rate of DR-nm23 protein expression was significantly higher in normal colorectal tissue than in adenoma and colorectal carcinoma (71.4% vs 38.6% and 35.7%, respectively; both P < 0.01). The positive rate of DR-nm23 protein expression was significantly lower in high-grade intraepithelial tumors than in low-grade intraepithelial tumors in the adenoma group (25.7% vs 59.1%, P < 0.05), and in metastatic colorectal carcinoma than in non-metastatic colorectal carcinoma (23.1% vs 44.1%, P < 0.05). The expression of DR-nm23 is negatively related to lymph node metastasis (P < 0.05). DR-nm23 expression is also closely related to histological type (χ² = 13.731, P < 0.01) and differentiation grade (χ² = 12.198, P < 0.01). The positive rate of DR-nm23 protein was higher in secondary tumors than in primary tumors in the metastatic colorectal carcinoma group though no significant difference was noted between them (P > 0.05).

CONCLUSION: Decreased DR-nm23 protein expression is closely related to tumor differentiation, carcinogenesis, progression and metastasis in colorectal carcinoma. DR-nm23 is an important parameter for evaluation of the biological behavior and prognosis of colorectal carcinoma.

Nme protein family evolutionary history, a vertebrate perspective

BACKGROUND

The Nme family, previously known as Nm23 or NDPK, is involved in various molecular processes including tumor metastasis and some members of the family, but not all, exhibit a Nucleoside Diphosphate Kinase (NDPK) activity. Ten genes are known in humans, in which some members have been extensively studied. In non-mammalian species, the Nme protein family has received, in contrast, far less attention. The picture of the vertebrate Nme family remains thus incomplete and orthology relationships with mammalian counterparts were only partially characterized. The present study therefore aimed at characterizing the Nme gene repertoire in vertebrates with special interest for teleosts, and providing a comprehensive overview of the Nme gene family evolutionary history in vertebrates.

RESULTS

In the present study, we present the evolutionary history of the Nme family in vertebrates and characterize the gene family repertoire for the first time in several non-mammalian species. Our observations show that vertebrate Nme genes can be separated in two evolutionary distinct groups. Nme1, Nme2, Nme3, and Nme4 belong to Group I while vertebrate Nme5, Nme6, Nme7, Nme8, and Nme9 belong to Group II. The position of Nme10 is in contrast more debatable due to its very specific evolutionary history. The present study clearly indicates that Nme5, Nme6, Nme7, and Nme8 originate from duplication events that occurred before the chordate radiation. In contrast, Nme genes of the Group I have a very different evolutionary history as our results suggest that they all arise from a common gene present in the chordate ancestor. In addition, expression patterns of all zebrafish nme transcripts were studied in a broad range of tissues by quantitative PCR and discussed in the light of the function of their mammalian counterparts.

CONCLUSION

This work offers an evolutionary framework that will pave the way for future studies on vertebrate Nme proteins and provides a unified vertebrate Nme nomenclature that is consistent with the nomenclature in use in mammals. Based on protein structure and expression data, we also provide new insight into molecular functions of Nme proteins among vertebrates and raise intriguing questions on the roles of Nme proteins in gonads.

EBNA3C can modulate the activities of the transcription factor Necdin in association with metastasis suppressor protein Nm23-H1

Previous studies have demonstrated the interaction between the Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA3C) and the metastatic suppressor Nm23-H1 both in vitro and in vivo (C. Subramanian, M. A. Cotter II, and E. S. Robertson, Nat. Med. 7:350-355, 2001). Importantly EBNA3C can reverse the ability of Nm23-H1 to suppress migration of human cells in vitro. EBNA3C contributes to EBV-associated human cancers by regulating transcription of a number of cellular and viral promoters as well as targeting and altering the transcription activities of the metastasis suppressor Nm23-H1. Furthermore, Necdin is a cellular protein which is highly induced in terminally differentiated cells; it contributes to the regulation of cell growth and is also known to interact with viral oncoproteins. In this report, we show that Nm23-H1 and EBNA3C can modulate the biological functions of Necdin in the context of EBV infection and transformation. The levels of Necdin were consistently lower in EBV-positive cells, and EBNA3C could change the subcellular localization of Necdin as well as rescue cells from the antiangiogenic and antiproliferative effects mediated by Necdin. We also show that Necdin directly interacts with Nm23-H1, resulting in modulation of the biochemical function of Nm23-H1 as well as the biological function of Necdin. Both EBNA3C and Nm23-H1 were able to rescue not only Necdin-mediated transcriptional repression of the downstream vascular endothelial growth factor promoter but also Necdin-mediated growth suppression and antiangiogenic effects on cancer cells. The majority of this response was mediated through amino acid residues 191 to 222 of Necdin, which are also known to be important for nuclear matrix targeting. These studies suggest a role for Necdin in the regulation of downstream cellular targets in a hypoxic environment in virus-associated human cancers.

The mammalian Nm23/NDPK family: from metastasis control to cilia movement

Nucleoside diphosphate kinases (NDPK) are encoded by the NME genes, also called NM23. They catalyze the transfer of gamma-phosphate from nucleoside triphosphates to nucleoside diphosphates by a ping-pong mechanism involving the formation of a high energy phospho-histidine intermediate [1, 2]. Besides their known functions in the control of intracellular nucleotide homeostasis, they are involved in multiple physiological and pathological cellular processes such as differentiation, development, metastastic dissemination or cilia functions. Over the past 15 years, ten human genes have been discovered encoding partial, full length, and/or tandemly repeated Nm23/NDPK domains, with or without N-or C-terminal extensions and/or additional domains. These genes encode proteins exhibiting different functions at various tissular and subcellular localizations. Most of these genes appear late in evolution with the emergence of the vertebrate lineage. This review summarizes the present knowledge on these multitalented proteins.

The mammalian Nm23/NDPK family: from metastasis control to cilia movement

Nucleoside diphosphate kinases (NDPK) are encoded by the NME genes, also called NM23. They catalyze the transfer of gamma-phosphate from nucleoside triphosphates to nucleoside diphosphates by a ping-pong mechanism involving the formation of a high energy phospho-histidine intermediate [1, 2]. Besides their known functions in the control of intracellular nucleotide homeostasis, they are involved in multiple physiological and pathological cellular processes such as differentiation, development, metastastic dissemination or cilia functions. Over the past 15 years, ten human genes have been discovered encoding partial, full length, and/or tandemly repeated Nm23/NDPK domains, with or without N-or C-terminal extensions and/or additional domains. These genes encode proteins exhibiting different functions at various tissular and subcellular localizations. Most of these genes appear late in evolution with the emergence of the vertebrate lineage. This review summarizes the present knowledge on these multitalented proteins.

Nm23-M5 mediates round and elongated spermatid survival by regulating GPX-5 levels

Nucleoside diphosphate (NDP) kinases are involved in numerous regulatory processes associated with proliferation, development, and differentiation. Previously, we cloned a new member of the NDPK family from mouse, Nm23-M5, which encodes a 211-amino acid protein and has 86% identity to the human Nm23-H5 [Hwang, K.C., Ok, D.W., Hong, J.C., Kim, M.O. and Kim, J.H. (2003) Cloning, sequencing, and characterization of the murine Nm23-M5 gene during mouse spermatogenesis and spermiogenesis. Biochem. Biophys. Res. Commun. 306, 198-207]. To better understand Nm23-M5 function, we generated transgenic mice with reduced Nm23-M5 levels in vivo using a short hairpin RNA (shRNA) knock-down system. Nm23-M5 expression was markedly reduced, as indicated by Northern and Western blot analysis. Nm23-M5 shRNA transgenic mice exhibited reduced numbers of haploid cells. Furthermore, the antioxidant enzyme glutathione peroxidase 5 (GPX-5) is regulated by Nm23-M5 at the level of both expression and activity. These results reveal that expression of Nm23-M5 plays a critical role in spermiogenesis by increasing the cellular levels of GPX-5 to eliminate reactive oxygen species.

Genome-wide discovery of functional transcription factor binding sites by comparative genomics: the case of Stat3

The identification of direct targets of transcription factors is a key problem in the study of gene regulatory networks. However, the use of high throughput experimental methods, such as ChIP-chip and ChIP-sequencing, is limited by their high cost and strong dependence on cellular type and context. We developed a computational method for the genome-wide identification of functional transcription factor binding sites based on positional weight matrices, comparative genomics, and gene expression profiling. The method was applied to Stat3, a transcription factor playing crucial roles in inflammation, immunity and oncogenesis, and able to induce distinct subsets of target genes in different cell types or conditions. A newly generated positional weight matrix enabled us to assign affinity scores of high specificity, as measured by EMSA competition assays. Phylogenetic conservation with 7 vertebrate species was used to select the binding sites most likely to be functional. Validation was carried out on predicted sites within genes identified as differentially expressed in the presence or absence of Stat3 by microarray analysis. Twelve of the fourteen sites tested were bound by Stat3 in vivo, as assessed by Chromatin Immunoprecipitation, allowing us to identify 9 Stat3 transcriptional targets. Given its high validation rate, and the availability of large transcription factor-dependent gene expression datasets obtained under diverse experimental conditions, our approach appears to be a valid alternative to high-throughput experimental assays for the discovery of novel direct targets of transcription factors.

Interaction of NDPK-D with cardiolipin-containing membranes: Structural basis and implications for mitochondrial physiology

Nucleoside diphosphate kinases (NDPKs/Nm23), responsible for intracellular di- and tri-phosphonucleoside homeostasis, play multi-faceted roles in cellular energetic, signaling, proliferation, differentiation and tumor invasion. The mitochondrial NDPK-D, the NME4 gene product, is a peripheral protein of the inner membrane. Several new aspects of the interaction of NDPK-D with the inner mitochondrial membrane have been recently characterized. Surface plasmon resonance analysis using recombinant NDPK-D and different phospholipid liposomes showed that NDPK-D interacts electrostatically with anionic phospholipids, with highest affinity observed for cardiolipin, a phospholipid located mostly in the mitochondrial inner membrane. Mutation of the central arginine (R90) in a surface exposed cationic RRK motif unique to NDPK-D strongly reduced phospholipid interaction in vitro and in vivo. Stable expression of NDPK-D proteins in HeLa cells naturally almost devoid of this isoform revealed a tight functional coupling of NDPK-D with oxidative phosphorylation that depends on the membrane-bound state of the enzyme. Owing to its symmetrical hexameric structure exposing membrane binding motifs on two opposite sides, NDPK-D could bridge liposomes containing anionic phospholipids and promote lipid transfer between them. In vivo, NDPK-D could induce intermembrane contacts and facilitate lipid movements between mitochondrial membranes. Most of these properties are reminiscent to those of the mitochondrial creatine kinase. We review here the common properties of both kinases and we discuss their potential roles in mitochondrial functions such as energy production, apoptosis and mitochondrial dynamics.

Nm23-H1 homologs suppress tumor cell motility and anchorage independent growth

Nm23-H1 suppresses metastasis, as well as in vitro cell motility, invasion and anchorage independent growth, in a variety of cancer models. Eight human homologs of Nm23 have been identified that share 26-88% identity with the prototype Nm23-H1. Here, we examine the potential of its homologs, -H2, DR-, -H4 and -H5, to inhibit in vitro correlates of metastasis in two highly metastatic human cell lines, MDA-MB-435 and MDA-MB-231. The metastatic cells were transfected with mammalian expression constructs containing the genes encoding for Nm23-H1, -H2, DR-, -H4 and -H5 and the resultant transfectants were analyzed by Boyden chamber motility and soft agar colonization assays. Nm23-H1 suppressed motility by 3.3- and 1.5-fold in MDA-MB-435 and MDA-MB-231 cells, respectively and inhibited anchorage independent growth in soft agar by 2.9- and 1.9-fold, respectively. None of the -H1 homologs were capable of suppressing motility in MDA-MB-435 cells, but in MDA-MB-231 cells, -H2 inhibited motility by 3-fold upon overexpression. When anchorage independent growth was assessed, -H2, -H4 and -H5 suppressed growth from 1.2- to 2.0-fold in both cell lines. Given their ability to suppress anchorage independent growth, Nm23-H1 homologs -H2, -H4 and -H5 may have some capacity to suppress metastasis. Motility suppression appears to be cell context dependent, but sequence disparities between -H1/H2 and the other family members may reveal regions critical for this inhibitory phenotype. Similarly, sequence differences between DR-Nm23 and its homologs may be important for anchorage independent growth suppression.

Epstein-Barr virus latent nuclear antigens can induce metastasis in a nude mouse model

Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus associated with the development of both lymphoid and epithelial tumors. The EBV critical latent antigens EBNA1 and EBNA3C interact with Nm23-H1, a known suppressor of cell migration and tumor metastasis. This interaction is critical for the regulation of downstream cellular genes involved in tumorigenesis and cell migration. The significance of these interactions was determined in nude mice using cancer cells expressing both EBV antigens and Nm23-H1. The EBV antigens promoted the growth of transformed cells in vivo, but their expression was less critical during the later stage of tumor development. The expression of Nm23-H1 affected the growth of cancer cells and suppressed their metastatic potential. This effect was effectively rescued by the expression of both EBV antigens. Interestingly, the prometastatic potential of EBNA3C was greater than that of EBNA1, which triggered a dramatic immune response, as indicated by increased spleen size and development of ascites in the mice. These studies now bridge the expression of the EBV antigens with tumorigenesis and metastasis and widen the range of potential targets for development of therapies for EBV-associated malignancies.

Proteomic approach to studying the cytotoxicity of YC-1 on U937 leukemia cells and antileukemia activity in orthotopic model of leukemia mice

To evaluate the effects of YC-1 on leukemia cell lines, PI incorporation was used to determine cell viability. YC-1 induced a dose- and time-dependent decrease in viability and apoptosis in YC-1-treated U937 cells. YC-1-induced apoptosis is a cyclic guanosine monophosphate (cGMP)-independent pathway. Proteomic analysis showed that the altered proteins include the significant regulation of HSP70, chaperonin, ATP synthase beta chains, and Chain F. Western blotting and immuno-cytochemistry stain showed that YC-1 treatment caused a time-dependent increase in cytosolic Cytochrome c, pro-caspase-9, Apaf-1, and the activation of caspase-9 and -3. Importantly, the in vivo antileukemia effects of YC-1 were evaluated in BALB/c mice inoculated with WEHI-3B orthotopic model. YC-1 enhanced survival rate and prevented the body weight loss in leukemia mice. The enlargement of spleen and lymph nodes were reduced in YC-1 treated than that in leukemia mice. H-E stain of spleen sections revealed that infiltration of immature myeloblastic cells into red pulp was reduced in YC-1-treated group. The apoptotic cells of splenocyte were significantly increased in YC-1 treated than that in leukemia mice by Tdt-mediated deoxyuridine triphosphate nick end labeling (TUNEL) assay. Taken together, we conclude that YC-1 acted against U937 cells in vitro via a mitochondrial-dependent apoptosis pathway, and in orthotopic leukemia model, YC-1 administered antileukemia activity.

Nm23-H1: a metastasis-associated gene

The protein product of nm23-H1 gene has activity of nucleoside diphosphate (NDP) kinase, which catalyzes the phosphorylation of nucleoside diphosphates to the corresponding nucleoside triphosphates. Reductions in nm23 expression have been significantly associated with aggressive behavior in melanoma, breast, colon, and gastric carcinomas. On the contrary, high levels of nm23 gene expression are noted in the advanced stage of thyroid carcinomas and associated with significant reductions in survival for neuroblastoma and osteosarcoma patients. Although expression of nm23/NDP kinase is divergent in various malignant tumors, its reduced expression seems to be related to increased metastatic potential in most carcinoma types. However, it is hypothesized that nm23 may play a tissue-specific role, and that different regulatory mechanisms may act in different tumors. In ovarian carcinoma, nm23-H1/NDP kinase may be correlated with some clinicopathologic characteristics. In cervical cancer, nm23-H1 is probably involved in cervical carcinogenesis and correlated with some aggressive parameters. Overexpression of nm23-H1 protein may indicate poor survival for cervical cancer patients. Other than histidine 118 residue (amino acid sequence 118: histidine) concerned with NDP kinase activity of nm23-H1, serine 120 (amino acid sequence 120: serine) related activity of histidine-dependent protein phosphotransfer was recently reported to be responsible for its biological suppressive effects. To inhibit metastatic potential, nm23-H1 is also demonstrated to co-immunoprecipitate the kinase suppressor of Ras and phosphorylate it, and therefore reduce activation of the extracellular signal-regulated kinase mitogen-activated protein kinase pathway in response to signaling.

Oligoribonuclease is a common downstream target of lithium-induced pAp accumulation in Escherichia coli and human cells

We identified Oligoribonuclease (Orn), an essential Escherichia coli protein and the only exonuclease degrading small ribonucleotides (5mer to 2mer) and its human homologue, small fragment nuclease (Sfn), in a screen for proteins that are potentially regulated by 3′-phosphoadenosine 5′-phosphate (pAp). We show that both enzymes are sensitive to micromolar amounts of pAp in vitro. We also demonstrate that Orn can degrade short DNA oligos in addition to its activity on RNA oligos, similar to what was documented for Sfn. pAp was shown to accumulate as a result of inhibition of the pAp-degrading enzyme by lithium, widely used to treat bipolar disorder, thus its regulatory targets are of significant medical interest. CysQ, the E.coli pAp-phosphatase is strongly inhibited by lithium and calcium in vitro and is a main target of lithium toxicity in vivo. Our findings point to remarkable conservation of the connection between sulfur- and RNA metabolism between E.coli and humans.

Epstein-Barr virus protein can upregulate cyclo-oxygenase-2 expression through association with the suppressor of metastasis Nm23-H1

Previous studies have demonstrated the interaction between the Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA3C) and the metastatic suppressor Nm23-H1 both in vitro and in vivo (C. Subramanian, M. A. Cotter II, and E. S. Robertson, Nat. Med. 7:350-355, 2001). EBNA3C can reverse the ability of Nm23-H1 to suppress migration of Burkitt's lymphoma and breast carcinoma cell lines in vitro. EBNA3C contributes to EBV-associated human cancers by regulating transcription of a number of cellular and viral promoters and by targeting and altering the transcription activities of the metastasis suppressor Nm23-H1. Cyclo-oxygenase-2 (COX-2), an inducible enzyme important in inflammation, is overexpressed in a variety of cancers and can influence cell migration. In this report we show that Nm23-H1 and EBNA3C can modulate expression of COX-2 in the context of EBV infection and transformation. The levels of COX-2 were consistently higher in EBV-positive cells than in EBV-negative cells. Additionally, we show that Nm23-H1 can upregulate the COX-2 promoter element in luciferase reporter assays, whereas EBNA3C alone did not affect the level of response but clearly contributed to an additive increase when coexpressed with Nm23-H1. The downstream effect of COX-2 expression was also evaluated and showed that prostaglandin E(2) levels increased with Nm23-H1 and that there was some level of cooperativity in the presence of EBNA3C. The majority of this response was mediated through the cyclic AMP response element and NF-kappaB sites. These studies suggest a potential role for COX-2 in EBV-associated human cancers.

Proteomic Analysis of Cellular Response to Microcystin in Human Amnion FL Cells

Microcystins (MC), the potent inhibitor of protein phosphatase 1 and 2A, are hepatotoxins of increasing importance due to its high acute toxicity and potent tumor promoting activity. So far, the exact mechanisms of MC-induced hepatotoxicity and tumor promoting activity have not been fully elucidated. To better understand the mechanisms underlying microcystin-RR (MC-RR) induced toxicity as well as provide the possibility for the establishment of biomarkers for MC-RR exposure, differential proteome analysis on human amnion FL cells treated by MC-RR was carried out using two-dimensional gel electrophoresis (2-DE) followed by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. Image analysis of silver-stained 2-dimensional gels revealed that 89 proteins showed significant differential expression in MC-RR treated cells compared with control, and 8 proteins were unique to MC-RR treated cells and 8 proteins were only detected in control cells. Sixty-six proteins were further identified with high confidence by peptide mass fingerprinting. Some of the identified differentially expressed proteins have clearly relationship with the process of apoptosis, signal transduction, and cytoskeleton alteration which are consistent with the literature. The functional implications of alterations in the levels of these proteins were discussed. However, most of which have not been reported previously to be involved in cellular processes responded to MC-RR. Therefore, this work will provide new insight into the mechanism of MC-RR toxicity.

Defective DNA mismatch repair determines a characteristic transcriptional profile in proximal colon cancers

BACKGROUND & AIMS

Colon cancers with defective DNA mismatch repair (MMR) have peculiar molecular, pathologic, and clinical features, including high-level microsatellite instability, conspicuous lymphocytic infiltration, preferential location in the proximal colon, and better prognosis. Our aim was to characterize the transcriptional profile of this colon cancer subset.

METHODS

An oligonucleotide microarray containing 12,625 probes was used to evaluate gene expression in 25 proximal colon cancers, 10 samples of normal colon mucosa, and 14 colon cancer cell lines. Transcriptional profiles of MMR-deficient cancers and cell lines were compared with those of their MMR-proficient counterparts.

RESULTS

Unsupervised analysis of microarray data showed that MMR status exerts a predominant influence on the gene expression profile of proximal colon cancers. Hierarchical clustering divided the cancers into 2 groups corresponding almost perfectly with their MMR status. Supervised analysis identified numerous gene expression changes that represent a genetic signature of MMR-deficient colon cancers. Changes in genes involved in apoptosis and the immune response were consistent with the better prognosis of MMR-deficient cancers. In MMR-deficient cancers and cell lines, 4-1BBL, a crucial gene in the anti-tumor immune response, was, respectively, 2.4 and 6.0 times more expressed than in their MMR-proficient counterparts. This difference was confirmed by quantitative reverse-transcription polymerase chain reaction and flow cytometric assessment of 4-1BBL protein expression in colon cancer cell lines. Our analysis also showed novel possible gene targets of microsatellite instability.

CONCLUSIONS

MMR inactivation produces distinct changes in the cellular messenger RNA pool, which is consistent with a unique tumorigenesis pathway.

Expression patterns of nm23 genes during mouse organogenesis

Nucleoside di-phosphate kinase enzyme (NDPK) isoforms, encoded by the nm23 family of genes, may be involved in various cellular differentiation and proliferation processes. We have therefore analyzed the expression of nm23-M1, -M2, -M3, and -M4 during embryonic mouse development. In situ hybridization data has revealed the differential expression of nm23 mRNA during organogenesis. Whereas nm23-M1 and -M3 are preferentially expressed in the nervous and sensory systems, nm23-M2 mRNA is found ubiquitously. Irrespective of the developmental state studied, nm23-M4 mRNA is only expressed at low levels in a few embryonic organs. In the cerebellum and cerebral cortex, nm23-M1, -M2, and -M3 are present in the neuronal differentiation layer, whereas nm23-M4 mRNA is distributed in the proliferating layer. Thus, nm23 mRNA is differentially expressed, and the diverse NDPK isoforms are sequentially involved in various developmental processes.

Gene expression profiling of the PPAR-alpha agonist ciprofibrate in the cynomolgus monkey liver

Fibrates, such as ciprofibrate, fenofibrate, and clofibrate, are peroxisome proliferator-activated receptor-alpha (PPARalpha) agonists that have been in clinical use for many decades for treatment of dyslipidemia. When mice and rats are given PPARalpha agonists, these drugs cause hepatic peroxisome proliferation, hypertrophy, hyperplasia, and eventually hepatocarcinogenesis. Importantly, primates are relatively refractory to these effects; however, the mechanisms for the species differences are not clearly understood. Cynomolgus monkeys were exposed to ciprofibrate at various dose levels for either 4 or 15 days, and the liver transcriptional profiles were examined using Affymetrix human GeneChips. Strong upregulation of many genes relating to fatty acid metabolism and mitochondrial oxidative phosphorylation was observed; this reflects the known pharmacology and activity of the fibrates. In addition, (1) many genes related to ribosome and proteasome biosynthesis were upregulated, (2) a large number of genes downregulated were in the complement and coagulation cascades, (3) a number of key regulatory genes, including members of the JUN, MYC, and NFkappaB families were downregulated, which appears to be in contrast to the rodent, where JUN and MYC are reported to upregulated after PPARalpha agonist treatment, (4) no transcriptional signal for DNA damage or oxidative stress was observed, and (5) transcriptional signals consistent with an anti-proliferative and a pro-apoptotic effect were seen. We also compared the primate data to literature reports of hepatic transcriptional profiling in PPARalpha-treated rodents, which showed that the magnitude of induction in beta-oxidation pathways was substantially greater in the rodent than the primate.

Expression of the nm23 homologues nm23-H4, nm23-H6, and nm23-H7 in human gastric and colon cancer

Eight members of the nm23-gene family have been described. The involvement of nm23-H1 and nm23-H2 in tumour progression and metastasis, as well as in gene regulation and apoptosis, has been shown in numerous studies. Whether nm23-H4, -H6, and -H7 play a role in tumours is, however, largely unknown. This study describes data on the expression of these three nm23 homologues in human colon and gastric cancer by real-time RT-PCR and immunohistochemistry. Increased expression of these genes, most strikingly nm23-H4 and -H7, was observed in the majority of tumours analysed. No correlation with tumour stage according to the TNM classification was found. In contrast, by immunohistochemical analysis, nm23-H4 and -H6 overexpression correlated with the intestinal tumour type in gastric cancer tissues, whereas no increased immunoreactivity for the three nm23 proteins was noted in the diffuse type tumour specimens. These findings indicate that nm23-H6, and particularly nm23-H4 and -H7, may be involved in the development of colon and gastric carcinoma, the latter possibly in a type-specific manner. A contribution to tumour progression or metastasis could not, however, be proven. Elucidation of the specific mechanisms by which the nm23 homologues nm23-H4, -H6, and -H7 are involved in tumour development requires further studies.

Epstein-Barr virus nuclear antigen 1 interacts with Nm23-H1 in lymphoblastoid cell lines and inhibits its ability to suppress cell migration

Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is expressed in the majority of latency programs in EBV-infected cells and is critical for the maintenance of EBV episomes in the infected cells. EBNA1 is also known to be involved in transcriptional activation and regulates expression of the EBV latent genes, including the EBNAs and LMP1. Thus, EBNA1 is a multifunctional protein with critical functions required for the persistence of the viral genome over successive generations, producing new daughter cells from the infected cell. We identify EBNA1 here as an interacting EBNA with the known suppressor of metastasis and cell migration, Nm23-H1. Nm23-H1 inhibits cell migration when expressed in cancer cells. We show that EBNA1 associates with Nm23-H1 in EBV-infected cells in vitro, as well as in lymphoblastoid cell lines (LCLs). Nm23-H1 predominantly localizes to the cytoplasm in BJAB and 293T cells; however, upon expression of EBNA1, Nm23-H1 is translocated to the nucleus in similar compartments to EBNA1, suggesting a potential functional role that is linked to EBNA1. Convincingly, in EBV-transformed LCLs Nm23-H1 is localized predominantly to the nucleus and colocalizes to similar compartment as EBNA1. Further, we tested the effects of EBNA1 on Nm23-H1-mediated suppression of cell migration and showed that EBNA1 rescues the suppression of cell migration mediated by Nm23-H1. These in vitro studies suggest that EBNA1 plays a critical role in regulating the activities of Nm23-H1, including cell migration, through a mechanism which involves direct interaction of this major regulator in EBV-infected cells.

Differential expression of the nm23 genes in the developing human trophoblast

NDP kinases are the non-specific enzymes which catalyse the synthesis of the NTPs through a transfer reaction using ATP as phosphoryl donor. In addition to their enzymatic activity, they display other not yet explained functions related to cell growth, differentiation and apoptosis, embryonic development, tumour progression and metastasis. In this study, the expression patterns of the three highly related NDP kinases A, B and C isoforms were investigated in the developing human trophoblast. Both NDP kinase A and B were found to be primarily present in the villous and extravillous cytotrophoblasts, while NDP kinase C was found almost exclusively in the syncytiotrophoblast layer. This suggests that NDP kinase A and B could be a marker for the mononuclear stage of differentiation of villous trophoblasts, while NDP kinase C could be a marker of the syncytiotrophoblast layer.

SwoHp, a nucleoside diphosphate kinase, is essential in Aspergillus nidulans

The temperature-sensitive swoH1 mutant of Aspergillus nidulans was previously identified in a screen for mutants with defects in polar growth. In the present work, we found that the swoH1 mutant swelled, lysed, and did not produce conidia during extended incubation at the restrictive temperature. When shifted from the permissive to the restrictive temperature, swoH1 showed the temperature-sensitive swelling phenotype only after 8 h at the higher temperature. The swoH gene was mapped to chromosome II and cloned by complementation of the temperature-sensitive phenotype. The sequence showed that swoH encodes a homologue of nucleoside diphosphate kinases (NDKs) from other organisms. Deletion experiments showed that the swoH gene is essential. A hemagglutinin-SwoHp fusion complemented the mutant phenotype, and the purified fusion protein possessed phosphate transferase activity in thin-layer chromatography assays. Sequencing of the mutant allele showed a predicted V83F change. Structural modeling suggested that the swoH1 mutation would lead to perturbation of the NDK active site. Crude cell extracts from the swoH1 mutant grown at the permissive temperature had approximately 20% of the NDK activity seen in the wild type and did not show any decrease in activity when assayed at higher temperatures. Though the data are not conclusive, the lack of temperature-sensitive NDK activity in the swoH1 mutant raises the intriguing possibility that the SwoH NDK is required for growth at elevated temperatures rather than for polarity maintenance.

Expression profiling of human keratinocyte response to ultraviolet A: implications in apoptosis

Ultraviolet A radiation from sunlight is a major human health concern, as it is not absorbed by the ozone layer and can deeply penetrate into the skin causing skin damage. To study the molecular mechanism involved in the ultraviolet A effect, human HaCaT keratinocytes were exposed to ultraviolet A at doses of 10 J per cm2 and 30 J per cm2. Ultraviolet A irradiation caused dose- and time-dependent apoptotic cell death, as evidenced by DNA fragmentation, flow cytometry, and the activation of caspase-3. To study the genes altered by ultraviolet A at an apoptosis-inducing dose (30 J per cm2), cells were harvested immediately after ultraviolet A treatment (0 h), and 6 h and 24 h after ultraviolet A exposure. Total RNA was extracted for microarray and real-time RT-PCR analysis, and cellular proteins were extracted for western blot analysis. Of the selected critical genes/proteins, the induction of c-Jun, c-myc, and p33ING1, and the repression of epidermal growth factor receptor, inhibitor of apoptosis protein, and survivin pathways, could be involved in ultraviolet-A-induced apoptosis. On the other hand, the late induction of cyclin D1 and cyclin-dependent kinase 4 was indicative of possible cell cycle recovery in surviving cells. Real-time RT-PCR analysis confirmed these results and a majority of the protein levels paralleled their corresponding RNA levels. In addition, ultraviolet A treatment altered the expression of genes involved in signal transduction, RNA processing, structural proteins, and metabolism in a time-dependent manner. This initial microarray analysis could advance our understanding of cellular responses to ultraviolet A exposure, and provide a platform from which to further study ultraviolet-A-induced apoptosis and carcinogenesis.

Multiple biochemical activities of NM23/NDP kinase in gene regulation

NM23/NDPk proteins play critical roles in cancer and development; however, our understanding of the underlying biochemical mechanisms is still limited. This large family of highly conserved proteins are known to participate in many events related to DNA metabolism, including nucleotide binding and nucleoside triphosphate synthesis, DNA binding and transcription, and cleavage of DNA strands via covalent protein-DNA complexes. The chemistry of the DNA-cleavage reaction of NM23-H2/NDPk is characteristic of DNA repair enzymes. Both the DNA cleavage and the NDPk reactions are conserved between E. coli and the human enzymes, and several conserved amino acid side chains involved in catalysis are shared by these reactions. It is proposed here that NM23/NDP kinases are important regulators of gene expression during development and cancer via previously unrecognized roles in DNA repair and recombination, and via previously unrecognized pathways and mechanisms of genetic control.

12-O-Tetradecanoylphorbol-13-acetate and UV Radiation-induced Nucleoside Diphosphate Protein Kinase B Mediates Neoplastic Transformation of Epidermal Cells

The molecular changes associated with early skin carcinogenesis are largely unknown. We have previously identified 11 genes whose expression was up- or down-regulated by 12-O-tetradecanoylphorbol-13-acetate (TPA) in mouse skin keratinocyte progenitor cells (Wei, S.-J., Trempus, C. S., Cannon, R. E., Bortner, C. D., and Tennant, R. W. (2003) J. Biol. Chem. 278, 1758-1768). Here, we show an induction of a nucleoside diphosphate protein kinase B (NDPK-B) gene in response to TPA or UV radiation (UVR). TPA or UVR significantly induced the expression of NDPK-B both in vivo hyperplastic mouse skin and in vitro mouse JB6 Cl 41-5a epidermal cells. Indeed, this gene was also up-regulated in TPA or UVR-mediated skin tumors including papillomas, spindle cell tumors, and squamous cell carcinomas, relative to adjacent normal skins. Functional studies by constitutive expression of nm23-M2/NDPK-B in TPA susceptible JB6 Cl 41-5a and TPA-resistant JB6 Cl 30-7b preneoplastic epidermal cell lines showed a remarkable gene dosage-dependent increase in foci-forming activity, as well as an enhancement in the efficiency of neoplastic transformation of these cells in soft agar but no effect on proliferation in monolayer cultures. Interestingly, stable transfection of the nm23-M2/NDPK-B del-RGD or G106A mutant gene in JB6 Cl 41-5a cells selectively abrogated NDPK-B-induced cellular transformation, implicating a possible Arg105-Gly106-Asp107 regulatory role in early skin carcinogenesis.

Cloning, sequencing, and characterization of the murine nm23-M5 gene during mouse spermatogenesis and spermiogenesis

Nucleoside diphosphate kinases (NDPKs) are conserved throughout evolution and have been shown to be involved in various biological phenomena. By functional screening in yeast, we identified a new member of the NDPK family, nm23-M5, which encodes a 211-amino acid protein with 86% identity to the human homolog Nm23-H5. Northern blot analysis revealed that nm23-M5 encodes two transcripts of 0.8 and 0.7kb, which are highly and specifically expressed in adult testis. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed that nm23-M5 transcripts first appear in pachytene spermatocytes and increase in abundance in subsequent stages. However, a low level of nm23-M5 mRNA was detected by RT-PCR in other tissues, such as ovary, brain, heart, and kidney. In situ hybridization studies showed that testicular nm23-M5 transcripts are localized in stage 12 to stage 16 spermatids in the neighboring lumen of seminiferous tubules. This distribution contrasts with that of Nm23-H5 transcripts, which are specifically found in spermatogonia and early spermatocytes. The heterologous expression of nm23-M5 in yeast cells confers protection from cell death induced by Bax, which is due to the generation of reactive oxygen species. Furthermore, overexpression of nm23-M5 in fibroblasts altered the cellular levels of several antioxidant enzymes, particularly glutathione peroxidase 5. Thus, we believe that the murine nm23-M5 gene plays an important role in late spermiogenesis by elevating the ability of late-stage spermatids to eliminate reactive oxygen species.

In vivo cross-linking of nm23/nucleoside diphosphate kinase to the PDGF-A gene promoter

Human isoforms A and B of nm23/nucleoside diphosphate (NDP) kinase, functionally important in development and cancer, have been reported to bind to DNA, and in particular isoform A to the PDGF-A promoter and isoform B to the c-myc promoter and to telomeric repeats. However, no direct proof of the binding in vivo has yet been obtained. To demonstrate this interaction, human erythroleukemic K562 cells were incubated with two different cross-linking reagents, formaldehyde or cis-diammine dichloro platinum H. The DNA-protein covalent complexes were isolated and analyzed by Western blotting. The positive immunochemical staining showed that in both conditions NDP kinase isoforms A and B were efficiently cross-linked to DNA in vivo. NDP kinase-linked DNA fragments obtained by immunoprecipitation, subjected to hybridization with different probes, showed a definite enrichment in the nuclease-hypersensitive silencer element of the PDGF-A promoter. No conclusive evidence was found by this technique of preferential hybridization with a nuclease-hypersensitive element of the c-myc promoter and with the telomeric TTAGGG repeats. The immunoprecipitated NDP kinase-DNA complexes are a promising material for the detection of other specific DNA sequences interacting with NDP kinase.

Multiple biochemical activities of NM23/NDP kinase in gene regulation

NM23/NDPk proteins play critical roles in cancer and development; however, our understanding of the underlying biochemical mechanisms is still limited. This large family of highly conserved proteins are known to participate in many events related to DNA metabolism, including nucleotide binding and nucleoside triphosphate synthesis, DNA binding and transcription, and cleavage of DNA strands via covalent protein-DNA complexes. The chemistry of the DNA-cleavage reaction of NM23-H2/NDPk is characteristic of DNA repair enzymes. Both the DNA cleavage and the NDPk reactions are conserved between E. coli and the human enzymes, and several conserved amino acid side chains involved in catalysis are shared by these reactions. It is proposed here that NM23/NDP kinases are important regulators of gene expression during development and cancer via previously unrecognized roles in DNA repair and recombination, and via previously unrecognized pathways and mechanisms of genetic control.

Hemophagocytic lymphohistiocytosis is associated with deficiencies of cellular cytolysis but normal expression of transcripts relevant to killer-cell-induced apoptosis

In 65 patients with hemophagocytic lymphohistiocytosis (HLH), we found an as yet undescribed heterogeneity of defects in cellular cytotoxicity when assay conditions were modified by the incubation time, the presence of mitogen, or interleukin-2 (IL-2). The standard 4-hour natural killer (NK) test against K562 targets was negative in all patients. In patients deficient in type 1 (n = 21), type 2 (n = 5), and type 4 (n = 8) HLH, negative NK function could be reconstituted by mitogen, by IL-2, or by prolongation of the incubation time (16 hours), respectively. Most patients (n = 31) displayed the type 3 defect, defined by a lack of any cellular cytotoxicity independent of assay variations. The characteristic hypercytokinemia also concerned counterregulatory cytokines, such as proinflammatory interferon-gamma (IFN-gamma), simultaneously elevated with suppressive IL-10 in 38% of types 1-, 2-, and 4-deficient patients and in 71% of type 3-deficient patients. Elevated IFN-gamma alone correlated with high liver enzymes, but sCD95-ligand and sCD25 did not-though these markers were expected to indicate the extent of histiocytic organ infiltration. Outcome analysis revealed more deaths in patients with type 3 deficiency (P =.017). Molecular defects were associated with homozygously mutated perforin only in 4 patients, but other type 3 patients expressed normal transcripts of effector molecules for target-cell apoptosis, including perforin and granzyme family members, as demonstrated by RNase protection analysis. Thus, target-cell recognition or differentiation defects are likely to explain this severe phenotype in HLH. Hyperactive phagocytes combined with NK defects may imply defects on the level of the antigen-presenting cell.

Characterization of the nm23-M2, nm23-M3 and nm23-M4 mouse genes: comparison with their human orthologs

The nm23 gene family is thought to be involved in physiopathological processes such as growth, differentiation and cancer promotion, progression or metastasis. We report here the mouse nm23-M3 and nm23-M4 complementary DNA sequences and the genomic cloning, characterization and tissue expression pattern of the nm23-M2, nm23-M3 and nm23-M4 genes, in comparison with their human and rat orthologs and with the human nm23-H1 and mouse nm23-M1 genes. The organization and structure of the members of this gene family are remarkably similar in human and rodents. Accordingly, the striking similarities between the human and mouse nm23 genes enable the use of mouse transgenic and knock-out models for studying the role of nucleoside diphosphate kinase isoforms in human physiopathology.