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

Mutations at the dimer interface and surface residues of Nm23-H1 metastasis suppressor affect its expression and function

The Nm23 metastasis suppressor family is involved in a variety of physiological and pathological processes including cell proliferation, differentiation, tumorigenesis, and metastasis. Given that Nm23 proteins may function as hexamers composed of different members of the family, especially Nm23-H1 and H2 isoforms, it is pertinent to assess the importance of interface and surface residues in defining the functional characteristics of Nm23 proteins. Using molecular modeling to identify clusters of residues that may affect dimer formation and isoform specificity, mutants of Nm23-H1 were constructed and assayed for their ability to modulate cell migration. Mutations of dimer interface residues Gly²² and Lys³⁹ affected the expression level of Nm23-H1, without altering the transcript level. The reduced protein expression was not due to increased protein degradation or altered subcellular distribution. Substitution of the surface residues of Nm23-H1 with Nm23-H2-specific Ser¹³¹ and/or Lys^124/135 affected the electrophoretic mobility of the protein. Moreover, in cell migration assays, several mutants with altered surface residues exhibited impaired ability to suppress the mobility of MDA-MB-231 cells. Collectively, the study suggests that disrupting the dimer interface may affect the expression of Nm23-H1, while the residues at α-helix and β-sheet on the surface of Nm23-H1 may contribute to its metastasis suppressive function.

Prognostic and clinicopathological value of NM23 expression in patients with breast cancer: A systematic review and meta-analysis

It is hypothesized that, NM23, as a metastasis suppressor gene, may be a good indicator of patients with breast cancer in most reports. The aim of our meta-analysis was to determine the prognostic value of NM23 in patients with breast cancer synthetically, by searching 3 databases, PubMed, EMBASE, and Web of Science, for relevant articles. The inclusion criteria, exclusion criteria, and the standard-of-quality assessment were used according to a previous protocol. The pooled odd ratios (ORs) and corresponding 95% CI were calculated to assess the primary end point, survival data, and the secondary end point, associations between NM23 expression and clinicopathological factors. Finally, funnel plots and Egger׳s linear regression test were used to assess the potential publication bias. Overall, 792 articles were retrieved in the initial search of databases, and 4968 patients were eventually pooled from 26 available studies selected out by 2 independent reviewers. The incorporative OR showed that elevated NM23 expression was associated with better overall survival (OR = 0.62; 95% CI: 0.52-0.74; P < 0.00001; I² = 0%; Ph = 0.46). In disease-free survival, we also obtained a good prognosis (OR = 0.30; 95% CI: 0.18-0.48; P < 0.00001; I² = 46%; Ph = 0.13). In addition, high-NM23 expression was correlated with well or moderate histologic grade, negative lymph node metastasis, and early tumor staging. Furthermore, publication bias was detected in overall survival but not in disease-free survival, and it could also be verified by Egger׳s test (P = 0.009 and P = 0.687, respectively). These results implied that NM23 might be an indicator of good prognosis in patients with breast cancer, although further researches need to be performed to confirm the prognostic value of NM23.

Extracellular NM23 Signaling in Breast Cancer: Incommodus Verum

The notion that breast cancers can survive in an individual patient in a dormant state only to grow as metastatic disease in the future, is in our view incontrovertibly established. Convincing too is the evidence that surgery to remove the primary tumor often terminates dormancy resulting in accelerated relapses. Accepting that many deaths due to breast cancer might be averted were we to understand the cellular mechanisms underlying escape from dormancy, we have examined the extracellular signals produced by breast cancers derived from women with metastatic breast disease. In this perspective, we explore the role of extracellular nucleotide signaling that we have proposed constitutes a pathological axis from the transformed tumor cell to the endothelium in the service of intravasation, dissemination, extravasation and angiogenesis. A role for the dinucleotide kinase NM23/NDPK (nucleoside diphosphate kinase) secreted by breast tumor cells in the generation of signals that stimulate vascular leakiness, anti-thrombosis, endothelial migration and growth, constitutes a mechanistic basis for escape from latency and offers putative therapeutic targets for breast cancer management not previously appreciated.

Effect of inhibition of the lysophosphatidic acid receptor 1 on metastasis and metastatic dormancy in breast cancer

BACKGROUND

Previous studies identified the human nonmetastatic gene 23 (NME1, hereafter Nm23-H1) as the first metastasis suppressor gene. An inverse relationship between Nm23-H1 and expression of lysophosphatidic acid receptor 1 gene (LPAR1, also known as EDG2 or hereafter LPA1) has also been reported. However, the effects of LPA1 inhibition on primary tumor size, metastasis, and metastatic dormancy have not been investigated.

METHODS

The LPA1 inhibitor Debio-0719 or LPA1 short hairpinned RNA (shRNA) was used. Primary tumor size and metastasis were investigated using the 4T1 spontaneous metastasis mouse model and the MDA-MB-231T experimental metastasis mouse model (n = 13 mice per group). Proliferation and p38 intracellular signaling in tumors and cell lines were determined by immunohistochemistry and western blot to investigate the effects of LPA1 inhibition on metastatic dormancy. An analysis of variance-based two-tailed t test was used to determine a statistically significant difference between treatment groups.

RESULTS

In the 4T1 spontaneous metastasis mouse model, Debio-0719 inhibited the metastasis of 4T1 cells to the liver (mean = 25.2 liver metastases per histologic section for vehicle-treated mice vs 6.8 for Debio-0719-treated mice, 73.0% reduction, P < .001) and lungs (mean = 6.37 lesions per histologic section for vehicle-treated mice vs 0.73 for Debio-0719-treated mice, 88.5% reduction, P < .001), with no effect on primary tumor size. Similar results were observed using the MDA-MB-231T experimental pulmonary metastasis mouse model. LPA1 shRNA also inhibited metastasis but did not affect primary tumor size. In 4T1 metastases, but not primary tumors, expression of the proliferative markers Ki67 and pErk was reduced by Debio-0719, and phosphorylation of the p38 stress kinase was increased, indicative of metastatic dormancy.

CONCLUSION

The data identify Debio-0719 as a drug candidate with metastasis suppressor activity, inducing dormancy at secondary tumor sites.

Purinergic mechanisms in breast cancer support intravasation, extravasation and angiogenesis

Several advances have recently expanded models of tumor growth and promoted the concept of tumor homeostasis, the hypothesis that primary tumors exert an anti-proliferative effect on both themselves and subclinical secondary metastases. Recent trials indicate that the characterization of tumor growth as uncontrolled is inconsistent with animal models, clinical models, and epidemiological models. There is a growing body of evidence which lends support to an updated concept of tumor growth: tumor homeostasis. In the case of breast cancer, if not all metastasizing tumors, these advances suggest an inconvenient truth. That is, if breast tumor cells metastasize to distant sites early in the tumorigenesis process, then removal of a breast tumor may hasten the development of its metastases. We explore the heretofore unappreciated notion that nucleotides generated by tumor cells following the secretion of an ADP-kinase can promote metastasis and support angiogenesis. Evidence is presented that blockade of the actions of nucleotides in the setting of newly diagnosed breast cancer may provide a useful adjunct to current anti-angiogenesis treatment.

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.

Docetaxel induces cell death through mitotic catastrophe in human breast cancer cells

Apoptosis has long been considered to be the prevailing mechanism of cell death in response to chemotherapy. Currently, a more heterogeneous model of tumor response to therapy is acknowledged wherein multiple modes of death combine to generate the overall tumor response. The resulting mechanisms of cell death are likely determined by the mechanism of action of the drug, the dosing regimen used, and the genetic background of the cells within the tumor. This study describes a nonapoptotic response to docetaxel therapy in human breast cancer cells of increasing cancer progression (MCF-10A, MCF-7, and MDA-mb-231). Docetaxel is a microtubule-stabilizing taxane that is being used in the clinic for the treatment of breast and prostate cancers and small cell carcinoma of the lung. The genetic backgrounds of these cells were characterized for the status of key pathways and gene products involved in drug response and cell death. Cellular responses to docetaxel were assessed by characterizing cell viability, cell cycle checkpoint arrest, and mechanisms of cell death. Mechanisms of cell death were determined by Annexin V binding and scoring of cytology-stained cells by morphology and transmission electron microscopy. The primary mechanism of death was determined to be mitotic catastrophe by scoring of micronucleated cells and cells undergoing aberrant mitosis. Other, nonapoptotic modes of death were also determined. No significant changes in levels of apoptosis were observed in response to docetaxel.

Transfection of keratin 18 gene in human breast cancer cells causes induction of adhesion proteins and dramatic regression of malignancy in vitro and in vivo

This study shows that high keratin 18 (K18) expression in tumor cells is associated with reduced invasiveness in vitro and lack of tumorigenicity in nude mice. We previously showed that high K18 expression correlated with a good prognosis and that reducing K18 expression increased the aggressiveness of established breast cancer cell lines. To confirm these observations, we transfected the human K18 gene into the human breast cancer cell line MDA-MB-231 and isolated a stable overexpressing clone. The forced K18 expression was associated with a complete loss of the previously strong vimentin expression in the parent cell line, induction of the K18 dimerization partner K8, and up-regulation of adhesion proteins. These changes were accompanied by a dramatic reduction in the aggressiveness of the K18 transfectants in vitro and in vivo. We conclude that forced reexpression of K18 causes at least partial redifferentiation of the tumor cell, followed by a corresponding regression of malignant phenotype.

Medroxyprogesterone acetate elevation of Nm23-H1 metastasis suppressor expression in hormone receptor-negative breast cancer

BACKGROUND

Reestablishment of metastasis suppressor gene expression may constitute a therapeutic strategy for high-risk breast cancer patients. We previously showed that medroxyprogesterone acetate (MPA), a progestin that has been tested as treatment for advanced breast cancer, elevates expression of the Nm23-H1 metastasis suppressor gene in hormone receptor-negative metastatic human breast carcinoma cell lines in vitro via a glucocorticoid receptor-based mechanism. Here, we tested whether MPA treatment inhibits metastatic colonization of a hormone receptor-negative breast cancer cell line in vivo.

METHODS

We tested the soft-agar colony-forming efficiency of untransfected MDA-MB-231T human breast carcinoma cells and MDA-MB-231T cells transfected with antisense Nm23-H1 in the presence and absence of MPA. Pharmacokinetic studies were used to establish dose and injection schedules that led to MPA serum levels in mice similar to those achievable in humans. For in vivo studies, nude mice were injected intravenously with MDA-MB-231T cells. After 4 weeks, mice were randomized to control or MPA arms. Endpoints included incidence, number, and size of gross pulmonary metastases; Nm23-H1 protein expression in gross metastases; and side effects. All statistical tests were two-sided.

RESULTS

MPA reduced colony formation of MDA-MB-231T cells by 40%-50% but had no effect on colony formation of Nm23-H1 antisense transfectants. Metastases developed in 100% (95% confidence interval [CI] = 78% to 100% and 77% to 100%, respectively) of control mice injected with MDA-MB-231T cells. In two independent experiments, only 73% (95% CI = 45% to 92%) and 64% (95% CI = 35% to 87%) of mice injected with 2 mg of MPA developed metastases. Mice injected with 2 mg of MPA showed reductions in the mean numbers, per mouse, of all metastases and of large (>3 mm) metastases (P = .04 and .013, respectively). Nm23-H1 was expressed at high levels in 43% of pulmonary metastases in MPA-treated mice but only 13% of metastases in untreated mice. Mice receiving at least 1-mg doses of MPA gained more weight than control-treated mice but exhibited no bone density alterations or abnormal mammary fat pad histology.

CONCLUSION

Our preclinical results show that MPA appears to elevate Nm23-H1 metastasis suppressor gene expression, thereby reducing metastatic colonization. The data suggest a new use for an old agent in a molecularly defined subset of breast cancer patients.

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.

Metastasis suppressor genes: basic biology and potential clinical use

Metastatic disease remains a significant contributor to morbidity and mortality in patients with breast cancer. An improved molecular and biochemical understanding of the metastatic process is expected to fuel the development of new therapeutic approaches. The suppression of tumor metastasis, despite tumor cell expression of oncogenes and metastasis-promoting events, has become a diverse and fruitful field of investigation. Although many genetic events promote metastasis, several genes show relatively reduced expression levels in metastatic tumor cells in mouse model systems and in aggressive human tumors. Re-expression of a metastasis-suppressor gene in a metastatic tumor cell line results in a significant reduction in metastatic behavior in vivo with no effect on tumorigenicity. The known metastasis-suppressor gene products nm23, KAI1, mitogen-activated protein kinase kinase 4, breast cancer metastasis suppressor-1, KiSS1, RHOGDI2, CRSP3, and vitamin D3-upregulated protein/thioredoxin interacting protein exhibit unexpected biochemical functions that have shed new light on signaling events that are important in metastasis. Most metastasis suppressors function at the translationally important stage of outgrowth of micrometastatic tumor cells at a distant site. We hypothesize that elevation of metastasis suppressor gene expression in micrometastatic tumor cells in the adjuvant high-risk population of patients with breast cancer will halt metastatic colonization and have a clinical benefit. DNA methylation inhibitors have shown limited promise in increasing metastasis-suppressor gene expression, and ligands of the nuclear hormone receptor family are currently under investigation in vitro and in vivo. Clinical testing of agents that increase metastasis-suppressor gene expression is expected to require tailored trial designs.

Potential markers predicting distant metastasis in axillary node-negative breast carcinoma

Prognostic parameters for axillary node-negative (ANN) breast cancer are still rare. Our aim was to establish potential markers that predict distant metastasis in ANN breast carcinoma and permit detection of the patients with high metastasis risk. A case control study was designed that comprised 64 ANN patients who developed distant metastasis during a 5-10 year follow-up period, 64 ANN patients with recurrence-free survival and 64 node-positive (ANP) comparitors. Immunohistochemistry and/or in situ hybridization were used to detect nm23, Cathepsin-D (Cath-D), Epidermal Growth Factor Receptor (EGFR) and Laminin Receptor (LR) in 192 cases. A significantly lower expression of both nm23 mRNA and protein was found in the ANN-group with poor prognosis compared with the ANN-group with good prognosis (p < 0.01). The protein levels of Cath-D, EGFR and LR were significantly higher in the ANN-group with poor prognosis and in the ANP-group compared with the ANN-group with good prognosis (p < 0.01 or p < 0.05), but no differences were found between the poor ANN-group and the ANP-group. Multiple regression analysis showed a close correlation of nm23, Cath-D and EGFR expression with occurrence of distant metastasis of ANN breast carcinoma. All markers except nm23 correlated with conventional histopathologic criteria such as tumor grade, margin and vessel invasion. The results suggest the combined detection of nm23, Cath-D and EGFR as predictive markers of distant metastasis in ANN breast cancer patients. Quantitative analysis together with clinicopathologic factors could contribute to estimate the potential risk of metastasis and select individual therapy regimen.

The breast cancer beta 4 integrin and endothelial human CLCA2 mediate lung metastasis

Adhesion of blood-borne cancer cells to the endothelium is a critical determinant of organ-specific metastasis. Here we show that colonization of the lungs by human breast cancer cells is correlated with cell surface expression of the alpha(6)beta(4) integrin and adhesion to human CLCA2 (hCLCA2), a Ca(2+)-sensitive chloride channel protein that is expressed on the endothelial cell luminal surface of pulmonary arteries, arterioles, and venules. Tumor cell adhesion to endothelial hCLCA2 is mediated by the beta(4) integrin, establishing for the first time a cell-cell adhesion property for this integrin that involves an entirely new adhesion partner. This adhesion is augmented by an increased surface expression of the alpha(6)beta(4) integrin in breast cancer cells selected in vivo for enhanced lung colonization but abolished by the specific cleavage of the beta(4) integrin with matrilysin. beta(4) integrin/hCLCA2 adhesion-blocking antibodies directed against either of the two interacting adhesion molecules inhibit lung colonization, while overexpression of the beta(4) integrin in a model murine tumor cell line of modest lung colonization potential significantly increases the lung metastatic performance. Our data clearly show that the beta(4)/hCLCA2 adhesion is critical for lung metastasis, yet expression of the beta(4) integrin in many benign breast tumors shows that this integrin is insufficient to bestow metastatic competence on cells that lack invasiveness and other established properties of metastatic cells.

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.

Correlation of MTS1/p16 and nm23 mRNA expression with survival in patients with peripheral synovial sarcoma

BACKGROUND AND OBJECTIVES

Tumor suppressor gene MTS1/p16 (cyclin-dependent kinase-4 inhibitor) and a putative tumor metastasis suppressor gene nm23 (nucleoside diphosphate A kinase) have been identified in a variety of human tumors but have not been well studied in mesenchymal neoplasms.

METHODS

Expression of nm23 and MTS1 mRNA was determined by quantitative analysis from paraffin-embedded tumor tissue. The series comprised 31 patients with localized primary synovial sarcoma of soft tissues who were followed for a median of 83 months.

RESULTS

Neither MTS1 nor nm23 expression levels correlated with the patient's age or sex, tumor type, depth, size, mitotic rate, or extent of tumor necrosis. In addition, there was no correlation between MTS1 and nm23 levels. Patients' survival was not related to sex, age, tumor type, location, mitotic rate, or MTS1 mRNA level. The only factors that correlated with poor survival in multivariate analysis were the presence of extensive tumor necrosis (> 15%) and higher levels of nm23 mRNA.

CONCLUSIONS

Our results suggest that increased expression level of nm23 mRNA may be implicated in the mechanism of tumor progression and is associated with poor survival in patients with synovial sarcoma.

Expression of a catalytically inactive H118Y mutant of nm23-H2 suppresses the metastatic potential of line IV Cl 1 human melanoma cells

Nm23-H1 and nm23-H2 are putative metastasis suppressor genes that encode nucleoside diphosphate kinase (NDPK) A and B. NDPKs form oligomers distributed between soluble and particulate fractions of cells and therefore may exert their effects as either soluble or bound proteins. To determine whether metastasis-related functions of NDPKs are mediated by their catalytic activity in membrane bound or soluble complexes, we have stably transfected highly metastatic human melanoma Line IV Cl 1 cells with wild-type and catalytically inactive (H118Y) nm23-H1 and nm23-H2 genes and assayed their metastatic potential in nude mice. Transfection with wild-type nm23-H1 and nm23-H2 genes and catalytically inactive nm23-H1 did not significantly (all p > 0.10) alter the metastatic potential of Line IV Cl 1 cells while transfection with catalytically inactive nm23-H2 significantly (p < 0.01) reduced their metastatic potential. The lack of effect of transfection with wild-type and catalytically inactive nm23-H1 suggests that neither soluble nor membrane bound NDPK A affect the metastatic potential of Line IV Cl 1 cells. The metastasis suppressive effect of catalytically inactive NDPK B overexpression suggests that competition with bound complexes containing catalytically active NDPK B inhibits metastasis of Line IV Cl 1 cells. These results imply that bound NDPK B promotes metastasis and suggest that inhibition of its function or of its binding to critical sites may be a useful approach to limit the development of metastases in human melanoma.

Nm23/nucleoside diphosphate kinase in human cancers

Tumor metastasis is the leading cause of death in cancer patients. From a series of tumor cohort studies, low expression of Nm23/NDP kinase has been correlated with poor patient prognosis and survival, lymph node infiltration, and histopathological indicators of high metastatic potential in a number of cancer types, including mammary and ovarian carcinomas and melanoma. In other tumor types, no correlation has been established. Transfection of Nm23/NDP kinase cDNA into highly metastatic breast, melanoma, prostrate and squamous cell carcinomas, and colon adenocarcinoma cells significantly reduced the metastatic competency of the cells in vivo. In culture, cell motility, invasion, and colonization were inhibited, whereas tumorigenicity and cellular proliferation were not affected, indicating that Nm23/NDP kinase acts as a metastasis suppressor.

Molecular biology of breast cancer metastasis. Genetic regulation of human breast carcinoma metastasis

The present is an overview of recent data that describes the genetic underpinnings of the suppression of cancer metastasis. Despite the explosion of new information about the genetics of cancer, only six human genes have thus far been shown to suppress metastasis functionally. Not all have been shown to be functional in breast carcinoma. Several additional genes inhibit various steps of the metastatic cascade, but do not necessarily block metastasis when tested using in vivo assays. The implications of this are discussed. Two recently discovered metastasis suppressor genes block proliferation of tumor cells at a secondary site, offering a new target for therapeutic intervention.

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.

Numerical aberrations of chromosome 17 in interphase cell nuclei of breast carcinoma cells: lack of correlation with abnormal expression of p53, neu and nm23 protein

The genes for p53, neu (c-erbB-2) and nm23 are all located on chromosome 17. Abnormal expression of their protein products is an important prognostic parameter. The aim of this study was to investigate if numerical aberrations of chromosome 17 are reflected in the expression of these markers. The immunohistochemical expression was analysed on histological specimens from 33 breast carcinomas. In situ hybridization (ISH) was performed on interphase cell nuclei in air-dried fine-needle aspirates from the same cases using a digoxigenin-labelled alpha-satellite probe for chromosome 17. ISH for chromosome 6, 7 and 12 was used additionally to give an estimate of ploidy. Of the carcinomas 76% were aneuploid, and numerical abnormalities of chromosome 17 were found in 34%. Abnormal p53 protein was expressed in 15% (five cases). All of these were aneuploid, but only one of them revealed aneusomy of chromosome 17. Neu overexpression was found in 18% of the tumours (six cases). Five of these were aneuploid, whereas two were aneusome for chromosome 17. Four cancers showed full (normal) expression of nm23 protein, whereas 29 had reduced expression. Reduced expression was found in 23 of 25 aneuploid tumours. Numerical aberrations of chromosome 17 were found equally in carcinomas with reduced and full nm23 protein expression. Abnormal numbers of chromosome 17 seem only to have a minor impact on these markers and are not reflected significantly in their expression.

Nm23-H1 expression in intrahepatic or extrahepatic metastases of hepatocellular carcinoma

AIMS/BACKGROUND

Decreased expression of nm23, a putative metastasis suppressor gene, has been reported to be related to either intrahepatic metastasis or a poor prognosis in hepatocellular carcinoma (HCC). The aim of this study was to elucidate the true role of nm23-H1 expression in both intrahepatic and distant metastases of HCC.

METHODS

Thirteen patients with single-nodule HCC, seven patients with HCC having satellite nodules and seven patients with HCCs having extrahepatic metastases were included in this study. The expression of nm23-H1 protein was immunohistochemically examined in both primary and metastatic nodules.

RESULTS

Ten of 13 single-nodule HCCs were found to overexpress nm23-H1 protein. All main tumors, having satellite nodules, were found to overexpress nm23-H protein, except for two HCCs, which only partially expressed nm23-H1 protein. Regarding the nm23-H1 expression in intrahepatic metastases, most nodules overexpressed the protein. The expression of nm23-H1 was found to be low in only one intrahepatic metastasis specimen, while its primary tumor was also found to show a low expression of nm23-H1 protein. Microscopic portal vein invasion was found in three of the five patients studied, and all cancer cells in portal invasion overexpressed nm23-H1 protein. Nm23-H1 protein was expressed in all distant metastatic tumors and the staining intensity of most metastatic nodules was similar to that of the primary tumors.

CONCLUSIONS

Our study demonstrated that nm23-H1 expression did not always decrease but instead tended to increase at both intrahepatic and extrahepatic metastatic sites. Based on these findings, nm23-H1 expression is not considered to be a reliable indicator of either intrahepatic or distant metastasis in HCC.

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.