Evaluation of the expression levels of nm23-H1 mRNA in primary breast cancer, benign breast disease, axillary lymph nodes and normal breast tissue

NDPKA is not just a metastasis suppressor - be aware of its metastasis-promoting role in neuroblastoma

NDPK-A, encoded by nm23-H1 (also known as NME1) was the first metastasis suppressor discovered. Much of the attention has been focused on the metastasis-suppressing role of NDPK-A in human tumors, including breast carcinoma and melanoma. However, compelling evidence points to a metastasis-promoting role of NDPK-A in certain tumors such as neuroblastoma and lymphoma. To balance attention on this contrariety of NDPK-A in different cancer types, this review addresses the metastasis-promoting role of NDPK-A in neuroblastoma. Neuroblastoma is an embryonic tumor, arising from neural crest cells that fail to differentiate into the sympathetic nervous system. We summarize and discuss nm23-H1 genetics and the prognosis of neuroblastoma, structural and functional changes associated with the S120G mutation of NDPK-A, as well as the evidence supporting the role of NDPK-A as a metastasis promoter. Also discussed are the NDPK-A relevant molecular determinants of neuroblastoma metastasis, and metastasis-relevant neural crest development. Because of NDPK-A's dichotomous role in tumor metastasis as both a suppressor and a promoter, tumor genome/exome profiles are necessary to identify the molecular drivers of metastasis in the NDPK-A network for developing tumor-specific therapies.

c-Abl and Arg induce cathepsin-mediated lysosomal degradation of the NM23-H1 metastasis suppressor in invasive cancer

Metastasis suppressors comprise a growing class of genes whose downregulation triggers metastatic progression. In contrast to tumor suppressors, metastasis suppressors are rarely mutated or deleted, and little is known regarding the mechanisms by which their expression is downregulated. Here, we demonstrate that the metastasis suppressor, NM23-H1, is degraded by lysosomal cysteine cathepsins (L,B), which directly cleave NM23-H1. In addition, activation of c-Abl and Arg oncoproteins induces NM23-H1 degradation in invasive cancer cells by increasing cysteine cathepsin transcription and activation. Moreover, c-Abl activates cathepsins by promoting endosome maturation, which facilitates trafficking of NM23-H1 to the lysosome where it is degraded. Importantly, the invasion- and metastasis-promoting activity of c-Abl/Arg is dependent on their ability to induce NM23-H1 degradation, and the pathway is clinically relevant as c-Abl/Arg activity and NM23-H1 expression are inversely correlated in primary breast cancers and melanomas. Thus, we demonstrate a novel mechanism by which cathepsin expression is upregulated in cancer cells (via Abl kinases). We also identify a novel role for intracellular cathepsins in invasion and metastasis (degradation of a metastasis suppressor). Finally, we identify novel crosstalk between oncogenic and metastasis suppressor pathways, thereby providing mechanistic insight into the process of NM23-H1 loss, which may pave the way for new strategies to restore NM23-H1 expression and block metastatic progression.

Tumor dormancy and the role of metastasis suppressor genes in regulating ectopic growth

Metastasis, or tumor growth in an ectopic site, may occur several years after apparently successful treatment of the primary malignancy. Clinical dormancy is seen in a large number of cancer patients, but once growth in an ectopic site initiates, current adjuvant therapies are inadequate and the majority of patients with metastatic disease will die. Many genes may regulate ectopic growth in a secondary site, including a small subset, termed the metastasis suppressor genes. Investigation into this class of genes holds promise in terms of gaining a greater understanding of tumor dormancy and how the process of metastasis may be naturally inhibited. This review will focus on the role of metastasis suppressor genes in tumor dormancy. Insights into the metastatic process from studies of metastasis suppressor genes may lead to novel targets for antimetastatic therapy through drug-induced reactivation of one or more of these genes and/or their respective signaling pathways.

Nm23-H1 metastasis suppressor expression level influences the binding properties, stability, and function of the kinase suppressor of Ras1 (KSR1) Erk scaffold in breast carcinoma cells

Metastatic disease is a significant contributor to cancer patient mortality. We previously reported that the Kinase Suppressor of Ras1 (KSR1) scaffold protein for the Erk mitogen-activated protein kinase pathway coimmunoprecipitated the metastasis suppressor protein Nm23-H1. We now hypothesize that altered expression levels of Nm23-H1 influence the binding properties, stability, and function of the KSR1 scaffold. Increased coimmunoprecipitation of Hsp90 with KSR1 was observed in either stable or transient transfectants of nm23-H1 in MDA-MB-435 human breast carcinoma cells. Similar trends were also observed in the cytoplasmic and nuclear fractions of cells. Cells expressing high levels of Nm23-H1 exhibited increased KSR1 degradation in the presence of either cycloheximide or an Hsp90-directed drug currently in clinical trial, 17-allylamino-17-demethoxygeldanamycin (17-AAG). In agreement with KSR1 degradation data, high-Nm23-H1-expression cells were preferentially inhibited in anchorage-independent colonization assays by 17-AAG. KSR1 scaffold binding patterns are dynamic in both the cytoplasmic and nuclear compartments, modulated by metastasis suppressor expression. Metastasis suppressor expression levels can impact traditional signaling pathways, such as the Erk pathway, resulting in altered tumor cell sensitivity to cancer therapeutics.

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.

Expression of nm23-H1 gene product in mediastinal lymph nodes from lung cancer patients

OBJECTIVE

Although numerous studies have shown that nm23-H1 gene product expression is inversely related to metastatic potential in some cancers, the expression in lymph nodes has not been studied in detail. An analysis of nm23-H1 gene product expression in mediastinal lymph nodes from lung cancer patients is reported.

METHODS

One hundred and thirty-four, randomly selected lymph nodes (63 with positive pathological lymph node status) from 39 surgically treated lung cancer patients were examined. Expression of nm23-H1 gene product was determined using specific monoclonal antibodies. Metastatic cancer cells were highlighted using anti-cytokeratin antibody.

RESULTS

Expression of nm23-H1 gene product in patients with less and more than 50% nodes-positive was 12/23 (52.2%) and 15/16 (93.8%) cases, respectively. Immunohistochemical studies with cytokeratin revealed micrometastasis in 6/39 (15.4%) patients and 9/71 (12.7%) nodes previously reported as cancer negative. Expression of nm23-H1 gene product in micrometastasis and metastasis-positive nodes was 5/9 (55.6%) and 55/63 (87.3%), respectively. We also found nm23-H1 gene product expression in germinal center cells. However, we found no relationship between expression of nm23-H1 gene product in germinal center cells and extent of metastasis.

CONCLUSIONS

Our study demonstrates a positive relationship between expression of nm23-H1 gene product and extent of metastasis in mediastinal lymph nodes from lung cancer patients. Our data for normal germinal center cells suggests that nm23-H1 gene product expression does not play a specific biological role in suppressing tumor metastasis in lung cancer.

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/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.

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.

Genetic analysis of breast cancer progression

At the histological level, breast tumors display a variety of morphologic lesions which suggest the existence of an increasingly aberrant pathway of intermediate steps leading to the invasive primary tumor and its metastatic dissemination. In order to obtain direct evidence for this presumed progression, underlying genetic changes must be identified. Analyses of primary breast tumors have revealed a large number of dominant and recessive gene alterations encompassing several cellular attributes and activities. It is quite likely that some of these alterations are of a causal nature and thus enable the tumor to attain distinctive malignant phenotypes, such as, dysregulated proliferation, invasion, angiogenesis, and ability to metastasize. Considerable heterogeneity has been observed in the sequence of acquisition of these genetic changes, which is substantiated by recent comparative analyses between carefully microdissected preinvasive and invasive tumor. The data are evaluated here in the context of existing models of breast cancer progression. Implication and prospects for translational application to the clinic are also discussed.