Metastasis Suppressor Gene Nm23 Research Articles

Notch signaling during development requires the function of awd, the Drosophila homolog of human metastasis suppressor gene Nm23.

BackgroundThe Drosophila abnormal wing discs (awd) belongs to a highly conserved family of genes implicated in metastasis suppression, metabolic homeostasis and epithelial morphogenesis. The cellular function of the mammalian members of this family, the Nm23 proteins, has not yet been clearly defined. Previous awd genetic analyses unraveled its endocytic role that is required for proper internalization of receptors controlling different signaling pathways. In this study, we analyzed the role of Awd in controlling Notch signaling during development.ResultsTo study the awd gene function we used genetic mosaic approaches to obtain cells homozygous for a loss of function allele. In awd mutant follicle cells and wing disc cells, Notch accumulates in enlarged early endosomes, resulting in defective Notch signaling. Our results demonstrate that awd function is required before γ-secretase mediated cleavage since over-expression of the constitutively active form of the Notch receptor in awd mutant follicle cells allows rescue of the signaling. By using markers of different endosomal compartments we show that Notch receptor accumulates in early endosomes in awd mutant follicle cells. A trafficking assay in living wing discs also shows that Notch accumulates in early endosomes. Importantly, constitutively active Rab5 cannot rescue the awd phenotype, suggesting that awd is required for Rab5 function in early endosome maturation.ConclusionsIn this report we demonstrate that awd is essential for Notch signaling via its endocytic role. In addition, we identify the endocytic step at which Awd function is required for Notch signaling and we obtain evidence indicating that Awd is necessary for Rab5 function. These findings provide new insights into the developmental and pathophysiological function of this important gene family.

Abstract A100: Alcohol promotes breast cancer cell invasion by regulating the Nm23-ITGA5 pathway

Abstract Introduction: Alcohol consumption increases breast cancer risk in women. Additionally, alcohol increases the metastatic ability of cancer cells. Metastasis suppressor genes encode proteins that have the ability to slow down or prevent the invasiveness of cancer cells, thus inhibiting the establishment of metastases. We analyzed the expression level of metastasis suppressor genes to determine the mechanisms by which alcohol increases the invasive ability of breast cancer cells. Methods: The invasiveness, or metastatic ability, of breast cancer cells was determined by the Boyden assay. To determine if alcohol increases invasion of breast cancer cells via the metastasis suppressor gene Nm23, we over-expressed or down-regulated Nm23 using siRNA-mediated knockdown; subsequently, we determined the effects of alcohol on the invasiveness of these cancer cells. Results: Results show that alcohol increased breast cancer cell invasion in a dose-dependent manner. Alcohol significantly decreased the expression of Nm23. Overexpression of Nm23 in breast cancer cells suppressed the effects of alcohol on the invasive ability of the cancer cells. Also, exposure of cancer cells to alcohol led to an increase in the expression level of the fibronectin receptor subunit ITGA5, and overexpression of Nm23 blocked the effects of alcohol. Further, the invasiveness of the breast cancer cells was inhibited when ITGA5 was knocked down by siRNA, and alcohol was unable to increase the invasiveness of the cancer cells when ITGA5 was knocked down. Conclusions: Results suggest that alcohol increases the invasive ability of breast cancer cells by down-regulating the metastatic suppressor Nm23 gene, which leads to increased expression of ITGA5. Consequently, up-regulated ITGA5 may increase the invasive ability of the cancer cells. Citation Information: Cancer Epidemiol Biomarkers Prev 2010;19(10 Suppl):A100.

Developmental function of Nm23/awd: a mediator of endocytosis

The metastasis suppressor gene Nm23 is highly conserved from yeast to human, implicating a critical developmental function. Studies in cultured mammalian cells have identified several potential functions, but many have not been directly verified in vivo. Here, we summarize the studies on the Drosophila homolog of the Nm23 gene, named a bnormal w ing d iscs (awd), which shares 78% amino acid identity with the human Nm23-H1 and H2 isoforms. These studies confirmed that awd gene encodes a nucleoside diphosphate kinase, and provided strong evidence of a role for awd in regulating cell differentiation and motility via regulation of growth factor receptor signaling. The latter function is mainly mediated by control of endocytosis. This review provides a historical account of the discovery and subsequent analyses of the awd gene. We will also discuss the possible molecular function of the Awd protein that underlies the endocytic function.

Transfection of the tumor metastasis suppressor gene nm23-H1 can targetly suppress the activity of extracellular signal-regulated protein kinase (ERK) in human high-metastasis large cell lung cancer cell line L9981

To investigate the influence of the tumor metastasis suppressor gene nm23 H1 on the activity of extracellular signal-regulated protein kinase (ERK) in human high metastasis large cell lung cancer cell line L9981. The levels of total ERK1/2 and phospho-pERK1/2 were determined with p44/42 MAP kinase antibody and dually phosphospecific phospho-44/42 MAP kinase antibody in human high-metastasis large cell lung cancer cell lines L9981 (cell line with nm23-H1 gene deletion), L9981-nm23-H1 (cell line with nm23-H1 transfected ) and L9981-PLXSN (cell line with vector transfected) by Western blot method, respectively. The activity of phospho-ERK1/2 was determined with an ERK1/2 assay kit by immunopreciptation and Western blot analysis. The expression levels of phospho-ERK1/2 kinase and the activity of phospho-ERK1/2 in the lung cancer cell line L9981-nm23-H1 were remarkably higher than those of the L9981 cell line and L9981-PLXSN cell line ( P < 0.01), but no significant difference in both the phospho-ERK1/2 expression and phospho-ERK1/2 activity was observed between the L9981 and L9981-PLXSN cell lines ( P > 0.05). There was no significant difference in the total ERK1/2 level among the three cell lines. nm23-H1 gene can obviously targetly suppress the activity of ERK1/2 in human high metastasis large cell lung cancer cell line L9981. This suggest that the mechanisms of nm23-H1 gene as a tumor metastasis suppressor gene may be related to its suppression to the MAPK/ERK signal transduction pathway.

Prediction of nodal spread of breast cancer by using artificial neural network-based analyses of S100A4, nm23 and steroid receptor expression.

The expression of tumour promoter gene S100A4, metastasis suppressor gene nm23, oestrogen and progesterone receptors, and tumour grade and size have been investigated for their potential to predict breast cancer progression. The molecular and cellular data have been analysed using artificial neural networks to determine the potential of these markers to predict the presence of metastatic tumour in the regional lymph nodes. This study shows that tumour grade and size are poor predictors. The relative expression of S100A4 and nm23 genes is the single most effective predictor of nodal status. Inclusion of oestrogen- and progesterone-receptor status with tumour grade and size markers improves prediction; however, there may be some overlap between steroid receptors and molecular markers. This study also underscores the power of artificial neural network techniques to predict the potential of primary breast cancers to spread to axillary lymph nodes. This could aid the clinician in determining whether invasive procedures of axially node dissection can be obviated and whether conservative forms of treatment might be appropriate in the management of the patient.

Clinical significance of nm23 expression and chromosome 17 numerical aberrations in primary gastric cancer.

The metastasis suppressor gene nm23 located on chromosome 17 might be one of the targets in deletions of chromosome 17. In this study, we analyzed the expression of nm23 and chromosome 17 aberrations in gastric cancer and assessed their clinicopathological and prognostic significance. In 103 gastric cancer patients, we examined nm23 expression by immunohistochemistry and detected chromosome 17 aberrations by fluorescence in situ hybridization. There was a significant difference in the expression of nm23 among differentiated histologic types (well > moderately > poorly) (p < 0.01). Negative expression of nm23 correlated with depth of invasion (p < 0.01), lymph node metastasis (p < 0.05), lymphatic invasion (p < 0.05), venous invasion (p < 0.05), poor prognosis (p < 0.05), and chromosome 17 loss (p < 0.05). Chromosome 17 aberrations broadly correlated with clinicopathological variables and were associated with poor prognosis (p < 0.05). Univariate analyses identified nm23 (p < 0.05), chromosome 17 aberrations (p < 0.05), tumor size (p < 0.01), depth of invasion (p < 0.0001), lymph node metastasis (P < 0.001), hepatic metastasis (p < 0.01), peritoneal dissemination (p < 0.01), and lymphatic invasion (p < 0.01) as significant prognostic factors. Multivariate analysis showed that expression of nm23 and chromosome 17 aberrations were not independent prognostic indicators. Our results indicate that negative expression of nm23 and chromosome 17 numerical aberrations correlate with tumor progression and poor prognosis but are not independent prognostic indicators.

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

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

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. 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. 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. 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.

Prognostic factors in advanced ovarian cancer

In this review, different factors with suspected effect on survival of patients with advanced ovarian cancer are analysed. The volume of residual disease after surgical debulking is one of the most important factors predicting outcome. However, the extent of cytoreduction may not be the only ‘responsible’ factor indicating a better prognosis; the underlying biology of those debulkable tumors may also play a role in defining the more favorable outcome. Seven reports have studied different prognostic factors by multivariate analysis: performance status, stage, age, grade, histology, tumor size, residual tumor, type of chemotherapy given, and ploidy status are the most common analysed parameters. A meta-analysis indicated that treatment with cisplatin and disease stage are the only independent prognostic variables. Some investigators have developed prognostic indexes with good predictive power, incorporating objective prognostic variables. This approach may be more useful than applying individual factors to each patient. The absolute titer of carbohydrate antigen 125, its decline after several courses of chemotherapy, or its half-life have been correlated with prognosis in some instances, but low sensitivity may be a problem. Other biologic factors with some prognostic potential in ovarian cancer are the expression of lung-resistance protein and the over-expression of c-erbB-2, both perhaps related to resistance to chemotherapy, the product of the metastasis suppressor gene nm23, the epidermal growth factor receptor, heat shock proteins (HSP-60), and plasma or ascites levels of macrophage colony-stimulating factor. Most of these predictors were explored in selected and often small series of patients, and their roles should be confirmed in well-designed confirmatory trials.

Nm23 gene expression and its correlation with lymph node metastasis in human lung cancer

Using labelled streptavidin-biotin (LSAB) method, we examined the expression of nucleoside diphosphate kinase(NDPK), the product of metastasis suppressor gene nm23, in human lung cancer. Of 88 patients tested, 48 (54.5%) showed positive staining. The positive staining rate was higher in adenocarcinoma (28/42, 66.7%) than in squamous cell carcinoma (20/46, 43.5%; P < 0.05). Higher incidence of positive staining was also found in squamous cell carcinoma without hilar or mediastinal lymph node metastasis (16/27, 59.3%) than in that with hilar or mediastinal lymph node involvement (4/19, 21.1%; P < 0.05). NDPK/nm23 was equally expressed in adenocarcinoma irrespective of lymph node status. In both cell types of carcinoma, expression of NDPK/nm23 was not correlated with tumor cell differentiation, nor was it correlated with the P-TNM staging. Our results suggest that NDPK/nm23 may play different roles in the pathogenesis and metastasis of human pulmonary squamous cell carcinoma and adenocarcinoma. Its expression levels are inversely correlated with lymph node metastasis in squamous cell carcinoma.