Nucleoside diphosphate kinase/NM23 expression in breast cancer: lack of correlation with lymph-node metastasis

A competitive cell-permeable peptide impairs Nme-1 (NDPK-A) and Prune-1 interaction: therapeutic applications in cancer

The understanding of protein-protein interactions is crucial in order to generate a second level of functional genomic analysis in human disease. Within a cellular microenvironment, protein-protein interactions generate new functions that can be defined by single or multiple modes of protein interactions. We outline here the clinical importance of targeting of the Nme-1 (NDPK-A)-Prune-1 protein complex in cancer, where an imbalance in the formation of this protein-protein complex can result in inhibition of tumor progression. We discuss here recent functional data using a small synthetic competitive cell-permeable peptide (CPP) that has shown therapeutic efficacy for impairing formation of the Nme-1-Prune-1 protein complex in mouse preclinical xenograft tumor models (e.g., breast, prostate, colon, and neuroblastoma). We thus believe that further discoveries in the near future related to the identification of new protein-protein interactions will have great impact on the development of new therapeutic strategies against various cancers.

Regulation of the metastasis suppressor Nm23-H1 by tumor viruses

Metastasis is the most common cause of cancer mortality. To increase the survival of patients, it is necessary to develop more effective methods for treating as well as preventing metastatic diseases. Recent advancement of knowledge in cancer metastasis provides the basis for development of targeted molecular therapeutics aimed at the tumor cell or its interaction with the host microenvironment. Metastasis suppressor genes (MSGs) are promising targets for inhibition of the metastasis process. During the past decade, functional significance of these genes, their regulatory pathways, and related downstream effector molecules have become a major focus of cancer research. Nm23-H1, first in the family of Nm23 human homologues, is a well-characterized, anti-metastatic factor linked with a large number of human malignancies. Mounting evidence to date suggests an important role for Nm23-H1 in reducing virus-induced tumor cell motility and migration. A detailed understanding of the molecular association between oncogenic viral antigens with Nm23-H1 may reveal the underlying mechanisms for tumor virus-associated malignancies. In this review, we will focus on the recent advances to our understanding of the molecular basis of oncogenic virus-induced progression of tumor metastasis by deregulation of Nm23-H1.

Dictyostelium discoideum nucleoside diphosphate kinase C plays a negative regulatory role in phagocytosis, macropinocytosis and exocytosis

Nucleoside diphosphate kinases (NDPKs) are ubiquitous phosphotransfer enzymes responsible for producing most of the nucleoside triphosphates except for ATP. This role is important for the synthesis of nucleic acids and proteins and the metabolism of sugars and lipids. Apart from this housekeeping role NDPKs have been shown to have many regulatory functions in diverse cellular processes including proliferation and endocytosis. Although the protein has been shown to have a positive regulatory role in clathrin- and dynamin-mediated micropinocytosis, its roles in macropinocytosis and phagocytosis have not been studied. The additional non-housekeeping roles of NDPK are often independent of enzyme activity but dependent on the expression level of the protein. In this study we altered the expression level of NDPK in the model eukaryotic organism Dictyostelium discoideum through antisense inhibition and overexpression. We demonstrate that NDPK levels affect growth, endocytosis and exocytosis. In particular we find that Dictyostelium NDPK negatively regulates endocytosis in contrast to the positive regulatory role identified in higher eukaryotes. This can be explained by the differences in types of endocytosis that have been studied in the different systems - phagocytosis and macropinocytosis in Dictyostelium compared with micropinocytosis in mammalian cells. This is the first report of a role for NDPK in regulating macropinocytosis and phagocytosis, the former being the major fluid phase uptake mechanism for macrophages, dendritic cells and other (non dendritic) cells exposed to growth factors.

Metastasis suppressor function of NM23-H1 requires its 3'-5' exonuclease activity

The metastasis suppressor NM23-H1 possesses 3 enzymatic activities in vitro, a nucleoside diphosphate kinase (NDPK), a protein histidine kinase and a more recently characterized 3'-5' exonuclease. Although the histidine kinase has been implicated in suppression of motility in breast carcinoma cell lines, potential relevance of the NDPK and 3'-5' exonuclease to metastasis suppressor function has not been addressed in detail. To this end, site-directed mutagenesis and biochemical analyses of bacterially expressed mutant NM23-H1 proteins have identified mutations that disrupt the 3'-5' exonuclease alone (Glu(5) to Ala, or E(5) A), the NDPK and histidine kinase activities tandemly (Y(52) A, H(118) F) or all 3 activities simultaneously (K(12) Q). Although forced expression of NM23-H1 potently suppressed spontaneous lung metastasis of subcutaneous tumor explants derived from the human melanoma cell line 1205LU, no significant metastasis suppressor activity was obtained with the exonuclease-deficient variants E(5) A and K(12) Q. The H(118) F mutant, which lacked both the NDPK and histidine kinase while retaining the 3'-5' exonuclease, also exhibited compromised suppressor activity. In contrast, each mutant retained the ability to suppress motility and invasive characteristics of 1205LU cells in culture, indicating that the NM23-H1 molecule possesses an additional activity(s) mediating these suppressor functions. These studies provide the first demonstration that the 3'-5' exonuclease activity of NM23-H1 is necessary for metastasis suppressor function and further indicate cooperativity of the 3 enzymatic activities of the molecule on suppression of the metastatic process.

Expression profile of genes associated with antimetastatic gene:nm23-Mediated metastasis inhibition in breast carcinoma cells

Metastases of various malignancies have been shown to be inversely related to the abundance of nm23 protein expression. However, the downstream pathways involved in nm23-mediated suppression of metastasis have not been elucidated. In the present investigation, we used cDNA microarrays to identify novel genes and functional pathways in nm23-mediated spontaneous breast metastasis. Microarray experiments were performed in a pair of cell lines, namely, C-100 (only vector transfected; highly metastatic) and H1-177 (nm23 transfected; low metastatic), derived from human mammary carcinoma cell line MDA-MB-435. The cDNA microarray analysis using GeneSpring software revealed significant as well as consistent alterations in the expression (up- and downregulation) of 2158 genes in a total of 18889 genes between high and low metastatic cells. Some of these genes were grouped into 6 functional categories, namely, invasion and metastasis, apoptosis and senescence, signal transduction molecules and transcription factors, cell cycle and repair, adhesion, and angiogenesis to extrapolate an association between these genes and different functional pathways involved in nm23-regulated metastasis. The results suggest that nm23 gene plays a major role in metastasis and its mechanism of action of metastasis suppression may involve downregulation of genes associated with cell adhesion, motility (integrins alpha2, -8, -9, -L and -V, collagen type VIII alpha1, fibronectin 1, catenin, TGF-beta2, FGF7, MMP14 and 16, ErbB2) and possibly certain tumor/metastasis suppressors (2 members of SWI/SNF-related matrix-associated proteins 2 and 5 and PTEN).

Differential expression of nm23 genes in adult mouse dorsal root ganglia

Nm23 has been identified as a gene family encoding different isoforms of nucleoside diphosphate kinase (NDPK). This protein is a key enzyme in nucleotide metabolism and has been shown to play important roles in various cellular functions. In the present study, we have investigated the expression of three isotypes in mouse dorsal root ganglia. In situ hybridization and reverse transcriptase-polymerase chain reaction analysis demonstrated high levels of nm23-M1, -M2, and -M3 mRNA expression in peripheral nervous tissue. Moreover, in situ hybridization also displayed a specific nuclear localization for nm23-M2 mRNA. Immunohistochemistry with light and electron microscopy on isoform-specific antibodies revealed a differential subcellular distribution of NDPK isoforms. Isoform A was mainly cytosolic, showing only partial association with organelles. In contrast, isoform B was also found in the nucleus, which is in agreement with its proposed role as a transcription factor. The results also indicate a preferential association of isoform C with endoplasmic reticulum and plasma membranes in neuronal cells. Furthermore, isoform C appeared to combine with other NDPK isoforms as demonstrated by double-labeling evidence by electron microscopy and might be responsible for binding NDPK oligomers to membranes. Thus, isoform C may be considered as a protein of importance for maintaining intracellular pools of GTP in the vicinity of membranes and, hence, for transmembrane signaling. The results indicate a high expression of NDPK isoforms, not only in the central but also in the peripheral nervous system. Their different subcellular compartmentalization suggests that they have isoform-specific roles in neuronal cell physiology.

Amplification and overexpression of PRUNE in human sarcomas and breast carcinomas-a possible mechanism for altering the nm23-H1 activity

PRUNE, the human homologue of the Drosophila gene, is located in 1q21.3, a region highly amplified in human sarcomas, malignant tumours of mesenchymal origin. Prune protein interacts with the metastasis suppressor nm23-H1, but shows impaired affinity towards the nm23-H1 S120G mutant associated with advanced neuroblastoma. Based on these observations, we previously suggested that prune may act as a negative regulator of nm23-H1 activity. We found amplification of PRUNE in aggressive sarcoma subtypes, such as leiomyosarcomas and malignant fibrous histiocytomas (MFH) as well as in the less malignant liposarcomas. PRUNE amplification was generally accompanied by high mRNA and moderate to high protein levels. The sarcoma samples expressed nm23-H1 mostly at low or moderate levels, whereas mRNA and protein levels were moderate to high in breast carcinomas. For the more aggressive sarcoma subtypes, 9/13 patients with PRUNE amplification developed metastases. A similar situation was observed in all breast carcinomas with amplification of PRUNE. Infection of NIH3T3 cells with a PRUNE recombinant retrovirus increased cell proliferation. Possibly, amplification and overexpression of PRUNE has the same effect in the tumours. We suggest that amplification and overexpression of PRUNE could be a mechanism for inhibition of nm23-H1 activity that affect the development or progression of these tumours.

P-glycoprotein, metallothionein and NM23 protein expressions in breast carcinoma

Cellular drug resistance and increased metastatic potential are the major obstacles in the successful treatment of cancer with chemotherapy. The aim of this study was to investigate whether the immunohistochemical expression of two proteins implicated in drug resistance (P-glycoprotein and metallothionein) and the product of the suppressor gene nm23 could be related to prognosis in breast cancer. Seventy-two patients with palpable or occult breast carcinoma, not treated with chemotherapy or endocrine therapy, were examined. Immunohistochemical methods were used to determine the expression of P-glycoprotein (PG), metallothionein (MT), nm23, as well as the estrogen receptor (ER), the p53 status, and the Ki67 index. The results were correlated with clinical and morphological features. Cytoplasmic and membrane-specific immunostainings of PG were seen exclusively in tumor cells and identified in 14 of 72 cases (19.4%). Only a statistically significant association with metastases, (p = 0.06) and recurrences (p = 0.1) was observed. MT-positive reaction was identified in the cytoplasm of the tumor cells in 47 (65.3%) cases. Statistical significance was associated with metastases (p = 0.07), but not with death or recurrences. Specific immunostaining of nm23 protein was seen only in the cytoplasm of tumor cells. A positive reaction was observed in 55 of 72 (89.3%) cases. Although a significant association between nm23 protein expression and other morphologic and immunohistochemical variables did not exist, we observed a higher morbidity in patients with the MT-positive/nm23-negative tumor phenotype. Univariate analysis for survival selected the following variables: histologic grade (p = 0.001), ER (p = 0.002), mitotic index (p = 0.005), Ki 67 index (p = 0.068), MT (p = 0.046) and PG (p = 0.085). The Cox model provided the following independent variables: histologic grade (p = 0.021) and metallothionein (p = 0.03). These data confirm the prognosis observed in patients with PG or metallothionein expression as well as the independence of these two variables. It also suggests that nm23 is not necessarily involved in the development of an invasive phenotype.

nm23-H1 expression defines a high-risk subpopulation of patients with early-stage epithelial ovarian carcinoma

The role of the nm23 gene in human ovarian cancer is still controversial. We studied the expression of the nm23-H1 gene in 247 human epithelial ovarian carcinomas. The patients were followed-up until their death, or for a minimum of 5 years if they survived. The expression of the gene was studied by means of immunohistochemistry and a semiquantitative scoring system considering the staining intensity and the number of reactive tumour cells. Patients carrying tumours with higher expression scores (4-6 on a scale from 0 to 6) had a significantly lower survival (P = 0.01) than the rest. Further stratified statistical analysis revealed that this effect was mainly attributable to the subgroup of patients with early-stage (I and II), well- and moderately differentiated tumours. In fact, a multivariate analysis carried out for this subset of patients showed nm23-overexpression to be the only significant independent predictor of an ominous prognosis. The association of nm23-overexpression with a worse prognosis was most probably not due to mutation of the nm23 gene, since mutational analysis in 60 tumours by means of single-strand conformational polymorphism and direct sequencing disclosed only one mutation, which was located outside the open reading frame. Our results seem to indicate that nm23 expression is associated with a significantly worse prognosis in early-stage, well-differentiated epithelial ovarian carcinoma, a finding with important clinical implications, considering that many patients with ovarian cancers showing these features do not undergo any further treatment beyond surgical staging. If confirmed, they could help in tailoring the treatment of these patients in the future.

Semiquantitative immunoblot analysis of nm23-H1 and -H2 isoforms in adenocarcinomas of the lung: prognostic significance

Total amounts of nm23 protein and relative levels of H1 and H2 isoforms were studied in 27 fresh-frozen samples of pulmonary adenocarcinoma and adjacent non-neoplastic tissues that were obtained at surgery. Semiquantitative immunoblotting with a monoclonal antibody (Pan-242) against nm23 protein demonstrated both isoforms, recognized as 20.5 kDa for H1 and 18.5 kDa for H2, to be present in all cases. Both H1 and H2 levels in neoplastic tissues were higher than in the corresponding non-neoplastic samples. Expression of H2 was usually greater than of H1. The H2/H1 ratio varied from 1.9 to 14.1 (mean value 5.2) in non-neoplastic tissues and 1.0-5.9 (mean value 2.5) in neoplastic tissues, although this ratio did not correlate with any prognostic factor like tumor size, nodal status or distant metastasis (TNM tumor stage). H1 and H2 levels were significantly lower (mean values 4.3 and 2.4) in well-differentiated than in moderately and poorly differentiated adenocarcinomas (8.3 and 3.0) (P < 0.03 and P < 0.05, respectively). These data indicate that H1 and H2 isoform levels correlate with histological differentiation, but not the metastatic potential or stage of pulmonary adenocarcinoma.

Expression of nm23 in normal, hyperplastic and neoplastic endometrial tissues

This study evaluated the expression of nm23 in curettage specimens from 63 cases of normal, hyperplastic and neoplastic endometrial tissues by immunohistochemistry. The histological diagnoses were as follows: normal proliferative (N = 5) or secretory (N = 5), simple hyperplasia (N = 11), complex hyperplasia (N = 9), atypical hyperplasia (N = 8) and adenocarcinoma (N = 25), consisting of endometrioid adenocarcinoma (N = 15), clear cell (N = 7) and serous papillary adenocarcinoma (N = 3). There was no immunostaining for nm23 protein in the 10 cases of normal endometria and in the 28 cases of endometrial hyperplasia. In contrast, 52% of the adenocarcinomas displayed a cytoplasmic staining pattern which was moderate to strong. This difference was statistically significant (p < 0.0001, chi-square test). nm23 expression in curettage specimens had no predictive value for determining the FIGO stage in the hysterectomy specimens (p = 0.2709, chi-square test). No significant difference for nm23 immunoreactivity was found between the histologic subtypes of endometrial adenocarcinoma (endometrioid versus serous papillary and clear cell, p = 0.1413, chi-square test). In this study, there was no immunostaining of normal endometria or of endometrial hyperplasia (including atypical endometrial hyperplasia) to support the hypothesis that expression of the nm23 gene product is related to the development of endometrial adenocarcinoma. In contrast, nm23 expression was upregulated in many cases of endometrial adenocarcinomas irrespective of the histologic subtype.

Evidence for interaction between human PRUNE and nm23-H1 NDPKinase

We have isolated a human and murine homologue of the Drosophila prune gene through dbEST searches. The gene is ubiquitously expressed in human adult tissues, while in mouse developing embryos a high level of expression is confined to the nervous system particularly in the dorsal root ganglia, cranial nerves, and neural retina. The gene is composed of eight exons and is located in the 1q21.3 chromosomal region. A pseudogene has been sequenced and mapped to chromosomal region 13q12. PRUNE protein retains the four characteristic domains of DHH phosphoesterases. The synergism between prune and awdK-pn in Drosophila has led various authors to propose an interaction between these genes. However, such an interaction has never been supported by biochemical data. By using interaction-mating and in vitro co-immunoprecipitation experiments, we show for the first time the ability of human PRUNE to interact with the human homologue of awd protein (nm23-H1). In contrast, PRUNE is impaired in its interaction with nm-23-H1-S120G mutant, a gain-of-function mutation associated with advanced neuroblastoma stages. Consistently, PRUNE and nm23-H1 proteins partially colocalize in the cytoplasm. The data presented are consistent with the view that PRUNE acts as a negative regulator of the nm23-H1 protein. We discuss how PRUNE regulates nm23-H1 protein and postulate possible implications of PRUNE in neuroblastoma progression.

Single strand DNA specificity analysis of human nucleoside diphosphate kinase B

Nucleoside diphosphate kinases (NDP kinases) form a family of oligomeric enzymes present in all organisms. Eukaryotic NDP kinases are hexamers composed of identical subunits (approximately 17 kDa). A distinctive property of human NDPK-B encoded by the gene nm23-H2 is its ability to stimulate the gene transcription. This property is independent of its catalytic activity and is possibly related to the role of this protein in cellular events including differentiation and tumor metastasis. In this paper, we report the first characterization of human NDPK-B.DNA complex formation using a filter-binding assay and fluorescence spectroscopy. We analyzed the binding of several oligonucleotides mimicking the promoter region of the c-myc oncogene including variants in sequence, structure, and length of both strands. We show that NDPK-B binds to single-stranded oligonucleotides in a nonsequence specific manner, but that it exhibits a poor binding activity to double-stranded oligonucleotides. This indicates that the specificity of recognition to DNA is a function of the structural conformation of DNA rather than of its specific sequence. Moreover, competition experiments performed with all nucleotides provide evidence for the contribution of the six active sites in the DNA.protein complex formation. We propose a mechanism through which human NDPK-B could stimulate transcription of c-myc or possibly other genes involved in cellular differentiation.

Prognostic significance of CD44 and nm23 expression in patients with stage II and stage IIIA gastric carcinoma

BACKGROUND AND OBJECTIVES

Predicting the prognosis in gastric carcinoma patients with intermediate stages is difficult. We investigated the prognostic impacts of CD44 and nm23 expression in a homogeneous group of patients with stage II and IIIA gastric carcinoma who had undergone curative resections.

METHODS

A total of 261 paraffin-embedded gastric carcinomas were stained with the monoclonal antibodies CD44 and nm23 using the labeled streptovidin biotin method.

RESULTS

The expression of CD44 and nm23 was detected, respectively, in 31.0% (81/261) and 70.1% (183/261) of all tumors. There was no correlation between CD44 expression and clinicopathological variables. However, nm23 was more frequently expressed in older patients with differentiated adenocarcinoma. A significant difference in 5-year survival rates was found between patients with CD44-positive (43.2%) and CD44-negative tumors (63.4%), (P = 0.0018). However, there was no significant difference in 5-year survival rates between patients with nm23-positive (54.7%) and nm23-negative tumors (62.7%) (P = 0.2734).

CONCLUSIONS

CD44 expression was a significant adverse prognostic factor in gastric carcinoma and may be a predictor of metastatic potential of the primary tumor. By contrast, immunohistochemical detection of nm23 expression was not a predictor of outcome of patients with gastric carcinoma.

The relationship between prognostic and predictive factors in the management of breast cancer

The discovery of new prognostic factors proceeds at a much more rapid pace than our knowledge of how to properly utilize this information in the management of patients with breast cancer, especially those with early breast cancer that has not metastasized to regional lymph nodes. Prognostic factors provide information on how the patient is likely to do regardless of treatment. Predictive factors provide information on whether a patient is likely to benefit from therapy. Most factors identified to date provide prognostic information, but relatively few provide information that is truly helpful in making a therapeutic decision in the management of individual patients. In large part this is because there has been insufficient study of the factor, especially prospective evaluations of the factor. Unfortunately this has resulted in the premature use of this information under the general rubric that patients with a poor prognosis deserve more treatment in spite of the fact that there may be no benefit from that therapy in the poor prognostic group.

Expression of nm23-H1 in colorectal cancer: no association with metastases, histological stage, or survival

The correlations of nm23-H1 expression in primary cancer lesions with the already confirmed 14 prognostic variables and survival were examined in 52 advanced colorectal cancer patients, because the clinical roles of nm23-H1 expression in the cancer lesions remain controversial. An immunohistochemical expression of nm23-H1 was found in 23 lesions (positive group) but not found in 29 lesions (negative group). No significant difference between the positive and negative groups was found according to 12 clinicopathological variables including vascular invasion, lymph node and liver metastases, and histological stage. The carcinoembryonic antigen levels (21.5+/-33.4 ng/ml) of the draining venous blood and argyrophilic nucleolar organizer regions score (3.35+/-1.36 per nucleus) of the cancer cells in the positive group were not significantly diffeent from those (34.1+/-102.9 ng/ml and 3.32+/-1.00 per nucleus, respectively) in the negative group. In addition, no significant difference was found in the survival curves or the 5-year survival rates of the positive and negative groups. From these results, it may be concluded that the nm23-H1 expression was not associated with the aforementioned prognostic variables and the prognosis of advanced colorectal cancer patients.

Expression of nm23 in gastric carcinoma: association with tumor progression and poor prognosis

BACKGROUND

Expression of nm23 has been shown to be inversely correlated with the metastatic potential of several human cancers. In the current study, the expression and prognostic impact of nm23 was immunohistochemically studied in 413 curatively resected gastric carcinomas.

METHODS

Tumor sections of the 413 gastric carcinomas were stained with a polyclonal antibody that was raised against the nm23-H1/NDP kinase A, which is identical to the nm23-H1 gene product.

RESULTS

Expression of nm23 was detected in 84.5% (n = 349) of all tumors, in the majority of cases (71.2%) causing a homogeneous staining reaction in more than 75% of tumor cells. Expression of nm23 was positively correlated with the intestinal type of tumor, according to the Lauren classification and advanced pT categories, and was also correlated with the presence of blood and lymphatic vessel invasion. In contrast, no correlation could be demonstrated between nm23 expression and lymph node involvement. As shown in univariate analysis, patients with nm23 positive tumors, especially those with nm23 positive diffuse-type carcinomas, had significantly shorter overall survival than patients with nm23 negative tumors (P = 0.03 and P = 0.0065, respectively). However, in a multivariate analysis that included the prognostic parameters pT category, pN category, and blood and lymphatic vessel invasion, this prognostic impact was not maintained.

CONCLUSIONS

In contrast to results for breast and colorectal carcinomas, our results for 413 gastric carcinomas showed that expression of the designated metastasis suppressor gene nm23 is correlated with aggressive tumor growth and poor prognosis but is not an independent prognostic marker.

Relationship of nm23 to proteolytic factors, proliferation and motility in breast cancer tissues and cell lines

Low expression of the antimetastatic gene nm23 has been associated with shorter overall survival in breast cancer. To better understand the mechanism(s) of action of this protein, we compared the levels of the nm23 protein in 152 breast cancer samples with other factors known to be involved in metastasis or related to prognosis. There was no significant relationship between either of the nm23 isoforms and cathepsin D (Cat-D), urokinase plasminogen activator (uPA), its inhibitor (PAI-1), steroid hormone receptors or ploidy status. A marginal inverse correlation was observed between per cent S-phase and nm23-H1 expression (r = -0.193, P = 0.047) and a positive correlation was observed between uPA receptor (uPAR) and both nm23-H1 (r = 0.263, P = 0.0018) and nm23-H2 (r = 0.230, P = 0.0064). The nm23-H1 gene was transfected into MDA-MB-231 human breast cancer cells and 12 clones were selected, of which two were characterized extensively. We found no significant differences in Cat-D, uPA, PAI-1 or uPAR, as a function of nm23 expression in either the MDA-MB-231 cells or the transfected clones. Compared with the parent cell line, we did observe a dose-dependent decrease in growth factor-stimulated motility and a decrease in metastatic potential in two clones with four- and eightfold elevated nm23-H1 expression, whereas the proliferative activities were similar. We conclude that the decreased metastatic potential might be related to down-regulation of growth factor-stimulated motility.

Relations of nm23 expression to clinicopathologic variables and proliferative activity of gastric cancer lesions

Relationships of nm23 expression and 12 clinicopathologic variables and proliferative activity of cancer cells were examined in 55 gastric cancer patients to clarify the effects of nm23 expression on the factors and activity in gastric cancer. Expression of nm23 was determined by immunohistochemically stained sections using a monoclonal antibody, nm23H-1. Proliferative activity was immunohistochemically evaluated by proliferating cell nuclear antigen (PCNA) labeling index (LI) using a monoclonal antibody PC10. Expression of nm23 was found in 24 lesions (positive group) but not in 31 lesions (negative group). With regard to clinicopathologic variables, a significant (p < 0.05) difference between the positive and negative groups was found in 1 of the 12 factors, depth of cancer invasion. PCNA LI (48.9 +/- 11.6%) of the former group was significantly (p < 0.05) higher than that (40.3 +/- 12.6%) ot the latter, although multiple regression analysis showed that nm23 expression was not one of the most influencing variables for PCNA LI. The results may suggest that expression of nm23 in gastric cancer lesions is correlated to tumor progression and/or proliferation rather than suppression of metastasis.

Prognostic significance of Nm23/NDPK expression in breast carcinoma, assessed on 10-year follow-up by automated and quantitative immunocytochemical assays

The Nm23 gene has been described as an antimetastatic gene; in some studies, disease progression in patients with solid tumours is related to Nm23 protein expression, which can be detected by immunohistochemical procedures. Detection of Nm23-H1 protein in breast cancer may be relevant for the monitoring of patient therapy, provided that the technical procedures are reliable and cost-effective. The aim of the present study was to determine the prognostic significance of Nm23, assessed by quantitative immunocytochemical assays (Nm23 ICAs), under optimal technical conditions. Nm23-H1 ICAs were performed on frozen sections, using an automated immunoperoxidase technique (Ventana) and computer-assisted analysis of digitized colour microscopic images (SAMBA), in a series of 168 breast carcinomas. The results of automated quantitative ICAs were correlated with patients' follow-up (129 months). Nm23-H1 immunocytochemical expression in histological sections of tumours in which more than 3 per cent of the surface area was positively stained was significantly (0.012) correlated with longer metastasis-free survival in both node-positive and node-negative groups of patients (P = 0.032 and P = 0.036, respectively) (Kaplan-Meier log-rank test, NCSS 6.0.1 software). Nm23 expression (cut-point 3 per cent) did not, however, correlate with overall survival, or with the recurrence-free survival. In multivariate analysis (proportional hazards regression, Cox model), the prognostic significance of Nm23 in terms of metastasis-free survival was independent of tumour size and grade, and of histological grade, in the entire cohort of patients. It is concluded that Nm23 immunodetection is only of limited practical clinical relevance in breast carcinoma, even when assessed under optimal technical conditions.

Association of nucleoside diphosphate kinase nm23-H2 with human telomeres

Telomeres, the ends of eukaryotic chromosomes, are essential structures formed by specific protein-DNA complexes that protect chromosomes from degradation and end-to-end fusion. TRF1, a double-stranded telomeric TTAGGG-repeat binding protein, is associated with mammalian telomeres and controls telomere length by inhibiting the action of telomerase. We identified human nucleoside diphosphate kinase nm23-H2 as a human TRF1-interacting protein by yeast two-hybrid screening. In vitro-binding assays using different recombinant nucleoside diphosphate kinases showed that TRF1 predominantly binds the nm23-H2 isoform rather than nm23-H1. Electrophoretic mobility shift analysis revealed that the recombinant nm23-H2 protein can bind the single-stranded telomeric TTAGGG-repeat while it cannot bind the double-stranded telomeric repeat. The synthetic 20 base oligoribonucleotide, which consists of the template sequence CUAACCCUAAC and the adjacent region of the RNA component of human telomerase, was also found to form the complex with the recombinant nm23-H2 protein. Furthermore, the affinity of telomerase for its substrate was increased in vitro by presence of the plentiful nm23-H2 protein. These findings indicate a close relationship between nm23-H2 and human telomeres and suggest a new biological role for nucleoside diphosphate kinase.

Automated and quantitative immunocytochemical assays of Nm23/NDPK protein in breast carcinomas

A series for Nm23-protein immunodetection was investigated in human breast carcinomas. Frozen sections were processed by automated immunoperoxidase procedure, and immunoprecipitates in positive tumors were quantified by processing digitized microscopic images. Nm23 immunohistochemical expression in tumors was correlated with clinicopathological data and with intra-tumoral proteins also detected by automated and quantitative immunohistochemistry. A positive Nm23 immunoreaction was observed in 58% of tumors, within cell cytoplasm. Nm23 expression was independent of the patient's age, and of tumor size, type and grade, but an inverse relationship was observed between Nm23 expression and axillary-lymph-node metastasis. An inverse relationship was also observed between Nm23 and P-53, CD-31, cathepsin D, tenascin and P-gp immunohistochemical expressions. But Nm23 expression was independent of c-erb-B product, growth fraction (MIB1/Ki67), and immunohistochemical expression of hormone receptors/P-S2. The results suggest that the anti-metastatic nm23 gene may partly act upon the regulation of tumor-cell proliferation (correlation with P-53) and may have some effects on epithelial-cell/stroma interactions (regulation of extracellular-matrix protease and of angiogenesis) independently of hormone sensitivity.

Immunohistochemical expression of nm23 gene product, nucleotide diphosphate kinase, in pancreatic neoplasms

CONCLUSION

Our findings suggest that contrary to the proposed role for the nm23 protein as a tumor metastasis suppressor, in pancreatic tumors, the nm23 protein does not play an important role as a suppressor against tumor metastasis.

BACKGROUND

The nm23 gene product, nucleotide diphosphate kinase, is believed to suppress tumor metastasis. Although a number of studies on many kinds of tumors have examined the relationship between nm23 expression and metastatic potential, the antimetastatic activity of nm23 remains controversial. The expression of the nm23 protein has not been examined in pancreatic tumors, except for a few reports on pancreatic duct cell carcinomas.

METHODS

We have investigated nm23 expression in pancreatic duct cell carcinomas, islet cell tumors, and ampullary carcinomas by immunohistochemical methods.

RESULTS

In 73 cases of pancreatic duct cell carcinomas, the nm23 expression was increased when compared with the adjacent normal pancreatic ducts; diffuse immunostaining was detected in 21 (29%) cases, focally positive immunostaining in 47 (64%) cases, and negative immunostaining in 5 cases (7%). All five negative samples were obtained from distant metastatic regions. However, there was no significant difference in the nm23 expression between primary tumors and regional lymph node metastases. Furthermore, there was no significant correlation between nm23 expression and the prognosis of the 55 resected cases. In the 15 cases of ampullary carcinomas, all 15 tumors were positive for nm23 protein (6 diffuse and 9 focal), and the staining intensity was stronger than in normal pancreatic ducts. There was no significant difference in the nm23 expression in the primary regions between patients with and without lymph node metastasis (2 diffuse and 5 focal out of 7 patients with lymph node metastasis, and 4 diffuse and 4 focal out of 8 patients without lymph node metastasis). All 12 islet cell tumors showed strong and diffuse staining for the nm23 protein.

Immunohistochemical analysis of the nm23 gene products in testicular seminoma

The nm23 gene has been identified as a metastasis suppressor gene. To clarify the role of nm23 as a metastasis suppressor gene in testicular seminoma, the expression of the nm23-H1 and -H2 proteins (human nucleoside-diphosphate kinase-A and -B) was immunohistochemically examined in 43 patients. Thirty-six (84%) and 21 (49%) of the 43 primary tumors were positive for the nm23-H1 and -H2 proteins, respectively. There was no significant difference in either nm23-H1 or -H2 expression between the 24 primary non-invasive tumors and the 19 primary invasive tumors, or between the 31 primary tumors without metastasis and the 12 primary tumors with metastasis. In all, and 5 of 6 metastatic tumors, the expression of nm23-H1 and -H2 proteins was observed, respectively, and the expression was not decreased in the metastatic tumors, compared to the primary tumors. In conclusion, the immunohistochemical expression of both the nm23-H1 and -H2 gene products is not associated with the metastatic status or the invasive status of testicular seminoma, and it is unlikely to be a useful non-metastatic indicator for testicular seminoma. Further studies are needed to elucidate the biological role of nm23.

Abnormal expression of four novel molecular markers represents a highly aggressive phenotype in breast cancer. Immunohistochemical assay of p53, nm23, erbB-2, and cathepsin D protein

BACKGROUND

In view of the cumulative results to date, p53, nm23, erbB-2, and cathepsin D are the most promising investigational prognostic factors in breast cancer.

OBJECTIVES

The clinical utility of these molecular markers to predict recurrence was evaluated.

METHODS

Archival pathology tissues of 100 breast cancer patients were analyzed by immunohistochemical assay. Molecular biologic data were merged with clinicopathologic variables.

RESULTS

Thirty-two patients (32%) had recurrence of disease at a median follow-up of 48 months (range 26-72 months). Investigational factor expression had statistical correlation for recurrence with increasing coexpression: one variable 20.6%, two variables 34.2%, three variables 47.1%, four variables 80.0% (P = 0.003). In univariate analysis, lymph node metastasis, tumor size, erbB-2 protein overexpression, and loss of nm23 protein expression were significant variables to determine recurrence; in multivariate analysis, node status and tumor size emerged as the most significant variables for recurrence.

CONCLUSIONS

Coexpression of the studied investigational variables functioned as significant prognostic correlates for recurrence. These findings suggest that the studied investigational prognostic factors possess the ability to discriminate a highly aggressive phenotype in breast cancer.

nm23--relationship to the metastatic potential of breast carcinoma cell lines, primary human xenografts, and lymph node negative breast carcinoma patients

BACKGROUND

Since the discovery of nm23 (nonmetastatic) by Steeg et al. in 1988, a number of tumor cohort studies have shown an inverse relationship between the levels of expression of the nm23-H1 protein and disease aggressiveness and tumor metastatic potential.

METHODS

The relationship between the expression of nm23 protein and the metastatic potential of human breast carcinoma was analyzed in cell lines, xenografts, and in a retrospective lymph node negative breast carcinoma population. The lymph node negative breast carcinoma study was comprised of 40 patients: 19 with nonrecurrent and 21 with recurrent disease. The 40 patients were matched according to age, cathepsin D, tumor size, percent S-phase, DNA ploidy, steroid receptor status, and tumor grade. Nm23-H1 protein levels in cell lines and xenografts were analyzed quantitatively using Western blot analyses and semiquantitatively in tissue sections using immunocytochemistry. Immunocytochemical analysis of lymph node negative breast tumors was graded as the percent of tumor staining positive for nm23 and the intensity of staining. The metastatic potentials of the cell lines and xenografts were assessed as the ability to form metastatic lesions in nude mice. In the lymph node negative breast carcinoma patients, the metastatic potential was characterized as the incidence of breast carcinoma recurrence.

RESULTS

The MCF-7 cell line expressed four- and tenfold higher levels of nm23-H1 than the highly metastatic MDA-MB-435 and MDA-MB-231 cells, respectively. Among the xenografts and cell lines, there was an inverse correlation between nm23-H1 expression and metastatic potential in athymic nude mice (correlation coefficient [R] = -0.51). The differences between the levels of nm23-H1 among the metastatic and nonmetastatic cell lines and xenografts were not statistically significant. Statistical analyses indicated that neither the intensity nor the percent of tumor staining positive for nm23 expression was correlated to the recurrence of breast carcinoma in the lymph node negative patient population that had been matched for other clinical prognostic markers.

CONCLUSIONS

There was an inverse correlation (R = 0.51) between the levels of nm23-H1 expression in cell lines and xenografts and the metastatic potential in nude mice. In the retrospective lymph node negative breast carcinoma population, no clear association was demonstrated between the expression of nm23 and breast carcinoma recurrence. This observation suggests the nm23 expression does not predict outcome in lymph node negative breast carcinoma patients.

Expression of the nm23 metastasis-suppressor gene product in skin tumors

Nm23 is a gene with a putative metastasis-suppressor function, whose expression is inversely correlated with the metastatic potential of some solid malignancies. Because very few data exist concerning the role of nm23 in skin tumors, we studied the immunohistochemical expression of nm23 gene product in frozen sections of normal skin and of 104 cutaneous benign or malignant, epithelial and mesenchymal tumors. Nm23 was found expressed within basal cells of the epidermis and its appendages. All basal cell carcinomas showed diffuse immunoreactivity predominating within cells located at the periphery of tumor masses; in contrast, most squamous cell carcinomas, premalignant lesions and the benign epithelial lesions studied showed very weak, if any, immunoreactivity. Benign nevi and most malignant melanomas expressed nm23 immunoreactivity and the pattern observed was similar between primary and metastatic lesions. These results show that nm23 is differentially expressed in cutaneous tumors. It seems likely that the strong immunoreactivity of basal cell carcinomas, contrasting with the almost non-expression in squamous cell carcinomas, reflects the different metastatic potential of these two types of tumors. In melanomas, no direct correlation between the metastatic phenotype and nm23 expression could be detected. Our results suggest that the nm23 gene is involved in cutaneous carcinogenesis; its precise role deserves further study.

NM23 gene expression in human breast carcinomas: loss of correlation with cell proliferation in the advanced phase of tumor progression

NM23 is a protein associated with tumor progression, expressed in all tissues and in human tumors. Reduced expression of NM23.H1 is related to high incidence of lymph node and distant metastasis or to poor prognosis of the patient in several human malignant tumors. In this study we analyze NM23 expression in non-neoplastic mammary tissues surrounding the tumoral lesions, in human mammary carcinomas and in lymph node metastasis. Our analysis shows that NM23.H1 expression is lower in the mammary cells surrounding the tumor than in the tumor itself. In the primary tumors we observed a negative trend between degree of local invasion and level of NM23.H1 expression. A further decrease of NM23.H1 was detected in the invasive tumors that metastasized to axillary lymph nodes and in the metastasis. NM23.H2 was always more highly expressed than NM23.H1, and reduced expression of NM23.H1 but not NM23.H2 was concordant with the presence of lymph node metastasis or local invasiveness of the primary tumor. A positive correlation between NM23.H1 mRNA content and cell growth rate of breast tumor cells has been confirmed. However, this trend was not maintained in cancer cells from tumors that metastasized to axillary lymph nodes and in metastatic cells; in these 2 situations the NM23.H1 mRNA content varied without any relationship to the proliferative rate of the cells. In addition, in comparison with the initial tumor, the metastatic cell population showed a strong decrease of NM23.H1 expression and increased proliferative activity.

Variability of nm23-H1/NDPK-A expression in human lymphomas and its relation to tumour aggressiveness

The nm23-H1 gene is a putative metastasis-suppressor gene encoding a 17 kDa protein with nucleoside diphosphate kinase activity. Expression of nm23-H1/NDPK-A correlates inversely with the metastasising potential of some human tumours and experimental animal cells. No nm23 expression studies exist for human malignant lymphomas so far. In this study, we examined nm23-H1 expression by Northern and immunohistochemical analysis in 106 primary lymphoma samples from patients with Hodgkin's disease (HD) (n = 15), high-grade non-Hodgkin's lymphoma (NHL) from different lineages (n = 71) and low-grade NHL (n = 20). Both inter- and intra-subtype variations in nm23-H1/NDPK-A expression levels were demonstrated by all disease subtypes. Besides this heterogeneity, a general trend towards highly malignant samples expressing higher nm23-H1/NDPK-A, levels than the low-grade lymphomas was observed. Both adult and childhood HD and high-grade NHL samples exhibited significantly higher NDPK-A expression than the low-grade NHL found only in adults. High nm23-H1/NDPK-A levels in lymphoma samples did not always reflect proliferative activity of tumour cells as monitored by Ki-67 antigen staining. Fifty samples were further investigated for possible mutations in the nm23-H1 coding sequence by means of reverse transcriptase-polymerase chain reaction (RT-PCR) and single-strand conformation polymorphism (SSCP) analysis. No mutation was found by this screening. Our results suggest a role for nm23-H1 expression in the disease aggressiveness of lymphomas.

NM-23 H1 immunohistochemistry is not useful as predictor of metastatic potential of colorectal cancer

This study aimed to investigate whether immunohistochemical staining for nm23-H1 protein in the primary tumour is correlated with tumour stage, tumour differentiation, DNA ploidy, cell proliferative index, p53 status and patient survival time in colorectal cancer. Full-cross colorectal cancer biopsies were collected from 202 consecutive surgical specimens between 1987 and 1990. Immunohistochemical expression of nm23-H1 protein was investigated in cryosections, using a monoclonal anti-nm23-H1 antibody (clone NM 301). The staining pattern was classified as follows: strong homogeneous intensity, moderate homogeneous intensity, moderate focal intensity, or as negative. Immunohistochemical expression of p53 was investigated using a monoclonal anti-p53 antibody (DO-7). The DNA ploidy and cell proliferative index were determined by flow cytometry. Possible correlation between nm23-H1 staining patterns and the other studied tumour characteristics was explored at the end of 1994. Median survival time of living patients was 66 months, range 50-93 months. No correlation was found between various nm23-H1 staining patterns and tumour stage, cell proliferative index or p53 status. Nm23-H1-negative tumours and tumours with moderate focal staining intensity were less differentiated than tumours with strong homogeneous or moderate homogeneous staining intensity (P < 0.05). Of the nm23-H1-negative tumours, a significantly higher number was near-diploid rather than aneuploid, as compared with those expressing positive nm23-H1 (P < 0.05). The number of dead patients in Dukes' stages B and C did not correlate significantly with the nm23-H1 staining pattern. The nm23-H1 staining pattern alone, or combined with either of the other explored tumour characteristics, did not correlate with patient survival time. Immunohistochemical studies of the nm23-H1 protein expression are of minor value in the staging and prognostic prediction of colorectal cancer.

The value of Nm23 expression as an independent prognostic indicator in primary thick melanoma

Whilst tumour thickness is of great value in predicting prognosis for groups of patients in different categories, it is of less value for individual patients. It has been proposed that expression of the nm23 gene, a putative tumour suppressor gene, is associated with improved outcome in a number of human neoplasms including malignant melanoma. We assessed nm23 expression in 22 patients who had primary melanomas > 3mm thick. Ten have survived to date and 12 died of melanoma. Using immunohistochemical methods, we found no significant differences in gene expression between the two groups.

Mutational analysis of NM23-H2/NDP kinase identifies the structural domains critical to recognition of a c-myc regulatory element

NM23-H2, a presumed regulator of tumor metastasis in humans, is a hexameric protein with both enzymatic (NDP kinase) and regulatory (transcriptional activation) activity. While the structure and catalytic mechanisms have been well characterized, the mode of DNA binding is not known. We examined this latter function in a site-directed mutational study and identified residues and domains essential for the recognition of a c-myc regulatory sequence. Three amino acids, Arg-34, Asn-69, and Lys-135, were found among 30 possibilities to be critical for DNA binding. Two of these, Asn-69 and Lys-135, are not conserved between NM23 variants differing in DNA-binding potential, suggesting that DNA recognition resides partly in nonconserved amino acids. All three DNA-binding defective mutant proteins are active enzymatically and appear to be stable hexamers, suggesting that they perform at the level of DNA recognition and that separate functional domains exist for enzyme catalysis and DNA binding. In the context of the known crystal structure of NM23-H2, the DNA-binding residues are located within distinct structural motifs in the monomer, which are exposed to the surface near the 2-fold axis of adjacent subunits in the hexamer. These findings are explained by a model in which NM23-H2 binds DNA with a combinatorial surface consisting of the "outer" face of the dimer. Chemical crosslinking data support a dimeric DNA-binding mode by NM23-H2.

Expression of NM23 in human melanoma progression and metastasis

NM23 is a putative metastasis-suppressor gene for some human cancers. Here we have studied NM23 expression during melanoma progression using Northern blotting and immunocytochemistry. There was no significant difference in the average amounts of NM23 mRNA between cell lines derived from metastatic and primary melanomas. The level of NM23 mRNA was also determined for three pairs of poorly metastatic parental (P) and their highly metastatic variant (M) cell lines; the ratios for M/P were 1.2, 0.98 and 0.80. Next we used immunocytochemistry to study NM23 protein in normal skin, benign naevi and primary and metastatic melanomas. Melanocytes in all normal skin and benign samples were positive for NM23; however most primary melanomas (7/11) were not stained by the antibody. All metastatic melanoma samples (5/5) were positively stained. Findings were similar with an antiserum reactive with both forms of NM23 (H1 and H2), and with an antibody specific for NM23-H1. No relationship was apparent between NM23 immunoreactivity in primary tumours and their aggressiveness or prognosis. Hence, in contrast to the situation described for murine melanoma, the amount of NM23 mRNA or protein in human melanoma did not correlate inversely with metastasis.

Evaluation of the prognostic significance of nm23/NDP kinase and cathepsin D in anal carcinomas. An immunohistochemical study

Reduced expression of nm23/NDP kinase and increased expression of cathepsin D seem to be correlated with a high metastatic potential for a variety of malignancies. Nm23/NDP kinase and cathepsin D have been correlated with several clinical variables, including survival in 96 patients with squamous cell carcinoma of the anal canal. Immunohistochemical methods were used on paraffin-embedded biopsies. Seventy-six (79%) anal carcinomas were nm23/NDP kinase positive, whereas 35 (36%) and 28 (29%) of the cases were cathepsin D positive in tumor cells and stromal cells, respectively. We have found no indication that the extent of cathepsin D staining has any prognostic significance. The overall survival of patients with tumours positive for nm23/NDP kinase in the cytoplasm was significantly shorter than that of patients with anal carcinomas negative for nm23/NDP kinase.

Potential prognostic value in human breast cancer of cytosolic Nme1 protein detection using an original hen specific antibody

The metastasis-suppressor nme gene (also called nm23), first identified in murine melanoma cells, exists as two forms in human: nme1 and nme2. However, only the lack of expression of nme1 has been related to distant metastasis appearance in human breast cancer. The aim of this work was first to raise specific antibodies to allow the analysis of Nme1 and then, with this specific tool, to evaluate the predictive value of Nme1 detection in cytosolic extracts of human breast tumours. We obtained a hen antibody that specifically reacts with Nme1 without any cross-reaction with Nme2. We analysed the expression of the protein in 59 human breast tumours and found a significant relationship between this expression and oestrogen receptor status (P<0.001). Moreover, Nme1 expression is related to metastasis-free survival (P<0.001) and survival of patients (P<0.001). The determination of Nme1 expression in primary tumours using our antibody should be an interesting predictive test of the metastasis for clinical investigations.

Expression of nm23-H1 and nm23-H2 protein in endometrial carcinoma

nm23 gene expression has been shown to be inversely correlated with tumour metastatic potential in some cancers but not in others. Examination was made of the expression of nm23-H1 and nm23-H2 gene products by immunohistochemistry and immunoblotting in 28 endometrial carcinomas. Immunohistochemistry indicated the cytoplasm of cancer cells to be positive, and myometrium and endometrial stromal cells negative, for nm23-H1 and -H2 protein. The staining intensity for these proteins was significantly stronger in well-differentiated adenocarcinomas (G1) than in those moderately differentiated (G2) (P < 0.05). nm23-H1 and -H2 proteins were shown by immunoblotting to be present at significantly higher levels in G1 than in G2 tumours (P < 0.05). Two of eight cases expressed high nm23-H1 and -H2 protein in poorly differentiated adenocarcinomas (G3). In G3 tumours, nm23 expression may be diverse. In this study, the expression of nm23-H1 and -H2 was not correlated with stage, metastasis, tumour size, myometrial invasion, oestrogen receptor, progesterone receptor or menopause. It follows from the findings presented above that the high expression of nm23-H1 and -H2 is positively correlated with histological differentiation.

Overexpression of nm23-H1 and nm23-H2 genes in colorectal carcinomas and loss of nm23-H1 expression in advanced tumour stages

Although a reduced expression of nm23 has been shown to correlate with a high metastatic potential in some human cancers, in colorectal cancers, conflicting data have been reported. As there are two homologous genes, nm23-H1 and nm23-H2, which encode the A and B subunits of nucleoside diphosphate kinase, efficient and simplified techniques were designed to selectively study nm23-H1 and -H2 expression in 35 colorectal cancers at both the protein and mRNA levels by immunoblotting, immunohistochemistry, and reverse transcription polymerase chain reaction (RT PCR) using specific antibodies and primers. Nm23-H1 and Nm23-H2 proteins were overexpressed in tumours compared with adjacent mucosa. This overexpression was lost, however, in some advanced cases: 89% and 81% of TNM (tumour, node, metastases) stages 0-II showed Nm23-H1 and -H2 overexpression, respectively, which significantly differed from 47% and 38% of stage III-IV tumours. Similar results were seen with nm23-H1 mRNA. Heterogenous labelling of tumoral cells was seen by immunohistological staining. This suggests a dichotomy: an overexpression of nm23-H1 and -H2 linked to early stages of cancer and a loss of nm23-H1 overexpression seen in more advanced stages. Therefore specific nm23-H1 determination should be evaluated as a prognostic factor in human colorectal carcinoma.

Immunohistochemical analysis of nm23 protein expression in malignant bone tumors

Expression levels of nm23 protein in 72 malignant bone tumors comprising 41 osteosarcomas, 22 chondrosarcomas, 6 Ewing's sarcomas, and 2 malignant fibrous histiocytomas were examined immunohistochemically, using anti-nm23 protein polyclonal antibody, and compared with 51 cases of benign bone tumors or tumor-like lesions. Malignant bone tumors showed significantly higher nm23 protein expression than benign bone tumors or tumor-like lesions (P < 0.0001). In chondrosarcoma, nm23 expression increased in high-grade tumors (grade I versus grade II and III: P = 0.0229). In the cases of osteosarcoma, however, grade IV osteosarcomas showed decreased expression of nm23 compared with grade III tumors (P = 0.0122). There was no significant relationship between nm23 expression and histological type. nm23 expression had no correlation with metastatic potential in osteosarcoma, although the therapy was not uniform in our cases. Furthermore, in 6 cases of osteosarcoma and 1 case of Ewing's sarcoma, there was no clear tendency for a decrease of nm23 in the metastatic sites compared with primary sites, as reported in breast cancer. These results showed that, in contrast to reports on breast cancer and experimental models, nm23 protein expression in human bone tumors may be associated with malignant potentiality, except in cases of osteosarcoma.

Immunohistochemical detection of nm23/NDP kinase and cathepsin D in medullary carcinomas of the thyroid gland

Reduced expression of nm23/NDP kinase and increased expression of cathepsin D seem to be correlated with the high metastatic potential in a variety of malignancies. The expression of nm23/NDP kinase and that of cathepsin D have been evaluated by means of an immunohistochemical technique in paraffin-embedded tissues from 44 primary medullary carcinomas of the thyroid gland (MCT) and from the corresponding lymph node metastases in 32 of these cases. In addition, lymph node metastases from 4 cases were studied. We found that 36 of 44 (82%) primary and 26 of 36 (72%) lymph node metastatic MCT were nm23/NDP kinase positive, whereas 14 of the 44 (32%) primary and 17 of the 36 (47%) lymph node metastatic MCT were cathepsin D positive. We found no indication that the nm23/NDP kinase level has any prognostic significance in MCT. The cathepsin D level is close to being prognostically significant in this study, and we cannot exclude the possibility that it could be of prognostic value. However, it seems to be quite weak, and therefore of little use in a clinical situation.

A human NDP-kinase B specifically binds single-stranded poly-pyrimidine sequences

Recently, a DNA binding protein 'PUF' was purified that binds to a poly-pyrimidine rich element in the human c-myc promoter. Cloning of the corresponding gene surprisingly identified this putative transcription factor as isoform B of the enzyme nucleoside diphosphate kinase (NDPK-B) [Postel et al. (1993) Science, 261, 478-480], the product of the potential metastasis suppressor gene nm23-H2. Using different recombinant NDP kinases, we demonstrate by electrophoretic mobility shift analysis (EMSA) that the NDP kinase DNA binding properties are predominantly observed with human isoform B. Unlike typical DNA binding proteins that are involved in transcriptional regulation, binding occurs to single-stranded DNA rather than to a double-stranded oligonucleotide. As a consequence, complexes of single-stranded DNA and NDPK-B are generated from double-stranded oligonucleotide hybrids in an ATP independent manner. In addition to the c-myc element, NDPK-B is binding in vitro to a variety of poly-pyrimidine rich sequences including dC or dT homo-oligomers, (CT)n dinucleotide repeats, the initiator region of the Adenovirus major late promoter and even poly-pyrimidine rich RNAs. The possible consequences of these findings in understanding the multiple roles of NDP kinase are discussed.

Phosphorylation of ATP-citrate lyase by nucleoside diphosphate kinase

Rat liver nucleoside diphosphate kinase (NDPK) and PC12 cell cytosol were used to determine whether NDPK could function as a protein kinase. NDPK was phosphorylated on its catalytic histidine using [gamma-32P]ATP, and the phosphorylated NDPK separated from [gamma-32P]ATP. The addition of phosphorylated NDPK to dialyzed PC12 cell cytosol resulted in the phosphorylation of a protein with a subunit molecular mass of about 120 kDa. This phosphorylation appeared to occur by a direct transfer of a phosphoryl group from the catalytic histidine of NDPK to a histidine on the 120-kDa protein. The 120-kDa protein was partially purified and shown by peptide sequencing to be ATP-citrate lyase. ATP-citrate lyase is the primary source of cytosolic acetyl-CoA. NDPK phosphorylated the histidine at the catalytic site of ATP-citrate lyase. This histidine can also be phosphorylated by ATP, and its phosphorylation is the first step in the conversion of citrate and CoA to oxaloacetate and acetyl-CoA by ATP-citrate lyase. The level of phosphorylation of PC12 cell ATP-citrate lyase by phosphorylated NDPK was comparable with that by ATP. Thus, in addition to its nucleoside diphosphate kinase activity, NDPK can function as a protein kinase.