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

Diagnostic significance of NM23 protein in ameloblastoma and ameloblastic carcinoma: An immunohistochemical study

BACKGROUND

Clinico-histopathologic assessment of patients with ameloblastoma and ameloblastic carcinoma remains the best diagnostic modality for the tumors. However, in cases where the criteria for arriving at a definitive diagnosis are not clearcut, the pathologist is faced with a dilemma and thus an imperative need for adjunct diagnostic methods.

OBJECTIVES

To evaluate/compare the immunohistochemical expression of NM23 in classical, borderline (atypical) ameloblastoma and ameloblastic carcinoma and to assess usefulness of NM23 in closing diagnostic gaps between ameloblastoma and ameloblastic carcinoma.

METHODS

Twenty-four (24) cases of ameloblastoma, 10 ameloblastoma with classical histopathologic features, 8 with nonclassical histopathology [atypical], and 6 cases of ameloblastic carcinoma were selected from cases seen at the Oral Pathology Laboratory of the Lagos State University College of Medicine, Nigeria. NM23 immunostaining protocol was done on the selected tissue blocks and evaluated using Sinicrope method. Analysis was done using R language.

RESULTS

Positive NM23 staining was observed in all cases of ameloblastoma and ameloblastic carcinoma, with more intense staining observed in the stellate reticulum-like areas than in the ameloblast-like areas. Ameloblastic carcinoma stained intensely with NM23 (100%) compared with atypical cases (37.5%) and ameloblastoma (20.0%; p = 0.04). The mean aggregate score was also significantly higher in AC (11 ± 2.4; p = 0.01). The mean aggregate score was also significant amongst growth pattern of ameloblastoma (p = 0 0.02).

CONCLUSIONS

The findings in this study reveal the usefulness of NM23 in differentiating ameloblastoma from ameloblastic carcinoma; a more comprehensive study with a larger sample size is recommended to corroborate or refute the findings in this study.

Mechanisms of action of NME metastasis suppressors - a family affair

Metastatic progression is regulated by metastasis promoter and suppressor genes. NME1, the prototypic and first described metastasis suppressor gene, encodes a nucleoside diphosphate kinase (NDPK) involved in nucleotide metabolism; two related family members, NME2 and NME4, are also reported as metastasis suppressors. These proteins physically interact with members of the GTPase dynamin family, which have key functions in membrane fission and fusion reactions necessary for endocytosis and mitochondrial dynamics. Evidence supports a model in which NDPKs provide GTP to dynamins to maintain a high local GTP concentration for optimal dynamin function. NME1 and NME2 are cytosolic enzymes that provide GTP to dynamins at the plasma membrane, which drive endocytosis, suggesting that these NMEs are necessary to attenuate signaling by receptors on the cell surface. Disruption of NDPK activity in NME-deficient tumors may thus drive metastasis by prolonging signaling. NME4 is a mitochondrial enzyme that interacts with the dynamin OPA1 at the mitochondria inner membrane to drive inner membrane fusion and maintain a fused mitochondrial network. This function is consistent with the current view that mitochondrial fusion inhibits the metastatic potential of tumor cells whereas mitochondrial fission promotes metastasis progression. The roles of NME family members in dynamin-mediated endocytosis and mitochondrial dynamics and the intimate link between these processes and metastasis provide a new framework to understand the metastasis suppressor functions of NME proteins.

Heterochiral dipeptide d-phenylalanyl- l-phenylalanine (H-D Phe-L Phe-OH) as a potential inducer of metastatic suppressor NM23H1 in p53 wild-type and mutant cells

In recent years, significant progress has been made to the use-case of small peptides because of their diversified edifice and hence their versatile application scope in cancer therapy. Here we identify the heterochiral dipeptide H-^D Phe-^L Phe-OH (F1) as a potent inducer of the metastatic suppressor NM23H1. We divulge the effect of F1 on the major EMT/metastasis-associated genes and the implications on the invasion and migration ability of cancer cells. The anti-invasive potential of F1 was directly correlated with NM23H1 expression. Mechanistically, F1 treatment elevated p53 levels as validated by localization and transcriptional studies. In the NM23H1 knockdown condition, F1 failed to induce any p53 expression/nuclear localization, indicating that the upregulation in p53 expression by F1 is NM23H1 dependent. We also demonstrate how the antimetastatic potential of F1 is primarily mediated through NM23H1 irrespective of the p53 status of the cell. However, both NM23H1 and a functional p53 protein in conjunction govern the apoptotic and cytostatic potential of F1. Coimmunoprecipitation studies unraveled the augmentation of the p53 and NM23H1 interaction in p53 wild-type cells. However, in p53 mutated cells, no such enrichment was evidenced. We employed mouse isogenic cell lines (4T-1 and 4T-1 p53) to determine the in vivo efficacy of F1 (spontaneous and experimental models). Decreased tumor volume in the cohort injected with 4T-1 p53 cells demonstrated that while the antimetastatic potential of F1 was reliant on NM23H1, p53 activation was required for ablation of primary tumor burden. Our findings unravel that F1 treatment induces significant abrogation of the migration, invasion and metastatic potential of both p53 wild-type and p53 deficient cancers mediated through NM23H1.

The mitochondrially-localized nucleoside diphosphate kinase D (NME4) is a novel metastasis suppressor

Background

Mitochondrial nucleoside diphosphate kinase (NDPK-D, NME4, NM23-H4) is a multifunctional enzyme mainly localized in the intermembrane space, bound to the inner membrane.

Results

We constructed loss-of-function mutants of NDPK-D, lacking either NDP kinase activity or membrane interaction and expressed mutants or wild-type protein in cancer cells. In a complementary approach, we performed depletion of NDPK-D by RNA interference. Both loss-of-function mutations and NDPK-D depletion promoted epithelial-mesenchymal transition and increased migratory and invasive potential. Immunocompromised mice developed more metastases when injected with cells expressing mutant NDPK-D as compared to wild-type. This metastatic reprogramming is a consequence of mitochondrial alterations, including fragmentation and loss of mitochondria, a metabolic switch from respiration to glycolysis, increased ROS generation, and further metabolic changes in mitochondria, all of which can trigger pro-metastatic protein expression and signaling cascades. In human cancer, NME4 expression is negatively associated with markers of epithelial-mesenchymal transition and tumor aggressiveness and a good prognosis factor for beneficial clinical outcome.

Conclusions

These data demonstrate NME4 as a novel metastasis suppressor gene, the first localizing to mitochondria, pointing to a role of mitochondria in metastatic dissemination.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-021-01155-5.

Expression profiles of p53/p73, NME and GLI families in metastatic melanoma tissue and cell lines

Unlike other tumours, TP53 is rarely mutated in melanoma; however, it fails to function as a tumour suppressor. We assume that its functions might be altered through interactions with several families of proteins, including p53/p73, NME and GLI. To elucidate the potential interplay among these families we analysed the expression profiles of aforementioned genes and proteins in a panel of melanoma cell lines, metastatic melanoma specimens and healthy corresponding tissue. Using qPCR a higher level of NME1 gene expression and lower levels of Δ40p53β, ΔNp73, GLI1, GLI2 and PTCH1 were observed in tumour samples compared to healthy tissue. Protein expression of Δ133p53α, Δ160p53α and ΔNp73α isoforms, NME1 and NME2, and N'ΔGLI1, GLI1FL, GLI2ΔN isoforms was elevated in tumour tissue, whereas ∆Np73β was downregulated. The results in melanoma cell lines, in general, support these findings. In addition, we correlated expression profiles with clinical features and outcome. Higher Δ133p53β and p53α mRNA and both GLI1 mRNA and GLI3R protein expression had a negative impact on the overall survival. Shorter overall survival was also connected with lower p53β and NME1 gene expression levels. In conclusion, all examined genes may have implications in melanoma development and functional inactivity of TP53.

Hierarchical investigating the predictive value of p53, COX2, EGFR, nm23 in the post-operative patients with colorectal carcinoma

The aim of this study was to evaluate the correlations between p53, COX2, EGFR, nm23 expression and the progression free survival (PFS) of post-operative patients with colorectal carcinoma. Immunohistochemistry was used to detect the expression of p53, COX2, EGFR and nm23 in 459 specimens from colorectal carcinoma patients. Kaplan-Meier estimates, Cox proportional hazard regression analyses and hierarchical analyses were performed on the collected data. Kaplan-Meier estimates analysis suggested that EGFR expression was as a negative predictor, the median PFS of patients with EGFR high expression was 21.73 months, and the median PFS of patients with low EGFR expression was 57.83 months (χ²=20.880, P<0.001); nm23 expression was positive predictive factor for the prognosis of patients with colorectal carcinoma, the median PFS of patients with high nm23 expression was 37.77 months, and the median PFS was 21.47 months in the patients with low nm23 expression (χ²=7.364, P=0.007). Cox regression analysis revealed that comparing with the patients with low expression of EGFR, the patients with high EGFR expression were at higher risk of tumor progression (HR=1.667, P=0.004); Comparing with the patients with high nm23 expression, the patients with nm23 low expression had a higher risk of tumor progression (HR=0.412, P<0.001); and the risk of tumor progression was higher in the patients with high EGFR expression and low nm23 expression (HR=0.245, P<0.001). Hierarchical analysis showed that EGFR expression mainly correlates with the PFS of TNM stage I-II colorectal cancer patients, the median PFS was 33.53 months in the TNM stage I-II colorectal cancer patients with high EGFR expression patients; The median PFS of the TNM stage I-II colorectal cancer patients with low EGFR expression was 70.43 months (χ²=9.530, P=0.002); The median PFS was 19.2 months in the TNM stage III-IV colorectal cancer patients with high expression EGFR, the PFS of the TNM stage III-IV colorectal cancer patients with low EGFR expression was 37.87 months (χ²=7.97, P=0.005). nm23 expression mainly correlates with the PFS of TNM stage III-IV colorecatal cancer patients. The median PFS was 47.27 months in TNM stage I-II colorectal cancer patients with nm23 high expression, the median PFS was 48.85 months in TNM stage I-II colorectal cancer patients with low nm23 expression (χ²=0.101, P=0.750); The median PFS was 28.8 months in TNM stage III-IV colorectal cancer patients with nm23 high expression, the median PFS was 14.7 months in TNM stage III-IV colorectal cancer patients with low nm23 expression (χ²=13.213, P<0.001). EGFR is mainly a predictive factor for the prognosis of post-operative patients with TNM stage I-II colorectal cancer, and nm23 is important for predicting the prognosis of patients with stage III-IV, and EGFR and nm23 could be as predictor of combination.

The NDPK/NME superfamily: state of the art

Nucleoside diphosphate kinases (NDPK) are nucleotide metabolism enzymes encoded by NME genes (also called NM23). Given the fact that not all NME-encoded proteins are catalytically active NDPKs and that NM23 generally refers to clinical studies on metastasis, we use here NME/NDPK to denote the proteins. Since their discovery in the 1950's, NMEs/NDPKs have been shown to be involved in multiple physiological and pathological cellular processes, but the molecular mechanisms have not been fully determined. Recent progress in elucidating these underlying mechanisms has been presented by experts in the field at the 10th International Congress on the NDPK/NME/AWD protein family in October 2016 in Dubrovnik, Croatia, and is summarized in review articles or original research in this and an upcoming issue of Laboratory Investigation. Within this editorial, we discuss three major cellular processes that involve members of the multi-functional NME/NDPK family: (i) cancer and metastasis dissemination, (ii) membrane remodeling and nucleotide channeling, and iii) protein histidine phosphorylation.

High expression of NME1 correlates with progression and poor prognosis in patients of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies that results from genes regulation via different pathways. NME/NM23 nucleoside diphosphate kinase 1 (NME1) is generally regarded as a metastasis suppressor, but its function in HCC is largely unknown. In our study, we explored the role of NME1 in HCC. By analyzing the gene expression omnibus (GEO) database, we discovered that NME1 was more highly expressed in HCC tumor tissues than non-HCC liver tissues (P < 0.001), and NME1 was significantly up-regulated in HCC tumor tissues than in adjacent normal tissues (P < 0.001). Then, validated by the enrolled HCC patients and The Cancer Genome Atlas (TCGA) database, NME1 was upregulated in HCC tumor tissues compared with matched adjacent normal tissue (P < 0.05). Besides, NME1 was down-regulated in Stage III/IV HCC patients than Stage I/II HCC patients (P = 0.009). Moreover, Kaplan-Meier analysis showed that HCC patients with high NME1 expression had poor overall survival (P = 0.004) and higher recurrence rate (P < 0.001). Our data revealed that NME1 was a special oncogene, and its expression was significantly associated with the progression and prognosis of HCC. NME1 may be a novel molecular biomarker for the targeted therapy and prognosis of HCC.

The role of NM23 in patients with colorectal cancer: A systematic review and meta-analysis

This meta-analysis was carried out to evaluate the relationship between NM23 expression and the prognosis of patients with colorectal cancer. We searched PubMed, EMBASE and Web of Science for relevant articles. The pooled odd ratios (ORs) and corresponding 95%CI were calculated to evaluate the prognostic value of NM23 expression in patients with colorectal cancer, and the association between NM23 expression and clinicopathological factors. In total, 2289 patients were pooled from 24 available studies. The incorporative OR combined by 16 studies with overall survival showed that high NM23 expression was associated with better overall survival (OR=0.67, 95%CI: 0.49-0.93, P=0.02, I ²=56%, Ph=0.004). And a new estimate without heterogeneity was produced when only combining high-quality studies (OR=0.70, 95%CI: 0.56-0.86, P=0.0007, I ²=46%). In disease free survival (DFS), we also obtained a good prognosis (OR=0.30, 95%CI: 0.14-0.68, P=0.004). Although we failed to find any significance in N status (P=0.10), elevated NM23 expression was related to well tumor differentiation (OR=0.60, 95%CI: 0.44-0.820, P=0.001) and Dukes' A&B (OR=0.55, 95%CI: 0.32-0.95, P=0.03). These results indicated that over-expressed NM23 might be an indicator of good prognosis, well tumor differentiation and Dukes' A&B of patients with colorectal cancer, but no significance was found in N status.

nm23 regulates decidualization through the PI3K-Akt-mTOR signaling pathways in mice and humans

STUDY QUESTION

Does nm23 have functional significance in decidualization in mice and humans?

SUMMARY ANSWER

nm23 affects decidualization via the phosphoinositide 3 kinase/mammalian target of rapamycin (PI3K-Akt-mTOR) signaling pathways in mouse endometrial stromal cells (ESCs; mESCs) and human ESCs.

WHAT IS KNOWN ALREADY

The function of nm23 in suppressing metastasis has been demonstrated in a variety of cancer types. nm23 also participates in the control of DNA replication and cell proliferation and differentiation.

STUDY DESIGN, SIZE AND DURATION

We first analyzed the expression profile of nm23 in mice during early pregnancy (n = 6/group), pseudopregnancy (n = 6/group) and artificial decidualization (n = 6/group) and in humans during the menstrual cycle phases and the first trimester. We then used primary cultured mESCs and a human ESC line, T-HESC, to explore the hormonal regulation of nm23 and the roles of nm23 in in vitro decidualization, and as a possible mediator of downstream PI3K-Akt-mTOR signaling pathways.

PARTICIPANTS/MATERIALS, SETTINGS AND METHODS

We evaluated the dynamic expression of nm23 in mice and humans using immunohistochemistry, western blot and real-time quantitative RT-PCR (RT-qPCR). Regulation of nm23 by steroid hormones was investigated in isolated primary mESCs and T-HESCs by western blot. The effect of nm23 knockdown (using siRNA) on ESC proliferation was analyzed by 5-ethynyl-2'-deoxyuridine staining (EdU) and proliferating cell nuclear antigen protein (PCNA) expression. The influence of nm23 expression on the differentiation of ESCs was determined by RT-qPCR using the mouse differentiation markers decidual/trophoblast PRL-related protein (dtprp, also named prl8a2) and prolactin family 3 subfamily c member 1 (prl3c1) and the human differentiation markers insulin-like growth factor binding protein 1 (IGFBP1) and prolactin (PRL). The effects of nm23 siRNA (si-nm23) and the PI3K inhibitor LY294002 on the downstream effects of nm23 on the PI3K-Akt-mTOR signaling pathway were estimated by western blot.

MAIN RESULTS AND THE ROLE OF CHANCE

NM23-M1 was specifically expressed in the decidual zone during early pregnancy and in artificially induced deciduoma, and NM23-H1 was strongly expressed in human first trimester decidua. The expression of nm23 was upregulated by oestradiol and progesterone (P < 0.05 versus control) in vitro in mESCs and T-HESC, and this was inhibited by their respective receptor antagonists, ICI 182,780 and RU486. Mouse and human nm23 knockdown decreased ESC proliferation and differentiation (P < 0.05 versus control). The PI3K-Akt-mTOR signaling pathways were downstream mediators of nm23 in mESCs and T-HESCs decidualization.

LIMITATIONS AND REASONS FOR CAUTION

Whether the nm23 regulates decidualization via the activation of AMPK, RAS, PKA, STAT3 or other signaling molecules remains to be determined. The role of nm23 in decidualization was tested in vitro only.

WIDER IMPLICATIONS OF THE FINDINGS

Results demonstrate that nm23 plays a vital role in decidualization in mice and humans and that nm23 gene expression is hormonally regulated. The downregulation of nm23 in decidua during the first trimester may be associated with infertility in women.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by the National Natural Science Foundation of China (grant nos. 81370731, 31571551 and 31571190), the Science and Technology Project of Chongqing Education Committee (KJ130309), open funding by the Chongqing Institute for Family Planning (1201) and the Excellent Young Scholars of Chongqing Medical University (CQYQ201302). The authors have no conflicts of interest to declare.

Prognostic Value of NME1 (NM23-H1) in Patients with Digestive System Neoplasms: A Systematic Review and Meta-Analysis

OBJECTIVE

There is a heated debate on whether the prognostic value of NME1 is favorable or unfavorable. Thus, we carried out a meta-analysis to evaluate the relationship between NME1 expression and the prognosis of patients with digestive system neoplasms.

METHODS

We searched PubMed, EMBASE and Web of Science for relevant articles. The pooled odd ratios (ORs) and corresponding 95%CI were calculated to evaluate the prognostic value of NME1 expression in patients with digestive system neoplasms, and the association between NME1 expression and clinicopathological factors. We also performed subgroup analyses to find out the source of heterogeneity.

RESULTS

2904 patients were pooled from 28 available studies in total. Neither the incorporative OR combined by 17 studies with overall survival (OR = 0.65, 95%CI:0.41-1.03, P = 0.07) nor the pooled OR with disease-free survival (OR = 0.75, 95%CI:0.17-3.36, P = 0.71) in statistics showed any significance. Although we couldn't find any significance in TNM stage (OR = 0.78, 95%CI:0.44-1.36, P = 0.38), elevated NME1 expression was related to well tumor differentiation (OR = 0.59, 95%CI:0.47-0.73, P<0.00001), negative N status (OR = 0.54, 95%CI:0.36-0.82, P = 0.003) and Dukes' stage (OR = 0.43, 95%CI:0.24-0.77, P = 0.004). And in the subgroup analyses, we only find the "years" which might be the source of heterogeneity of overall survival in gastric cancer.

CONCLUSIONS

The results showed that statistically significant association was found between NME1 expression and the tumor differentiation, N status and Dukes' stage of patients with digestive system cancers, while no significance was found in overall survival, disease-free survival and TNM stage. More and further researches should be conducted to reveal the prognostic value of NME1.

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

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

Evaluation of serum nucleoside diphosphate kinase A for the detection of colorectal cancer

We previously described the over-expression of nucleoside diphosphate kinase A (NDKA) in tumours and serum from colorectal cancer (CRC) patients, suggesting its use as biomarker. In this study we evaluated the diagnostic accuracy of serum NDKA to detect advanced neoplasia (CRC or advanced adenomas). Furthermore, the performance of NDKA was compared with the faecal immunochemical test (FIT). The study population included a case-control cohort and a screening cohort (511 asymptomatic first-degree relatives of CRC patients that underwent a colonoscopy and a FIT). Serum NDKA was elevated in CRC patients in the case-control cohort (p = 0.002). In the screening cohort, NDKA levels were higher for advanced adenomas (p = 0.010) and advanced neoplasia (p = 0.006) compared to no neoplasia. Moreover, elevated NDKA was associated with severe characteristics of adenomas (≥3 lesions, size ≥ 1 cm or villous component). Setting specificity to 85%, NDKA showed a sensitivity of 30.19% and 29.82% for advanced adenomas and advanced neoplasia, respectively. NDKA combined with FIT (100 ng/mL cut-off) detected advanced adenomas and advanced neoplasia with 45.28% and 49.12% sensitivity, with specificity close to 90%. The combination of serum NDKA and FIT can improve the detection of advanced neoplasia, mainly for lesions located on the proximal colon, in asymptomatic individuals with CRC family-risk.

NME2 reduces proliferation, migration and invasion of gastric cancer cells to limit metastasis

Gastric cancer is one of the most common malignancies and has a high rate of metastasis. We hypothesize that NME2 (Nucleoside Diphosphate Kinase 2), which has previously been considered as an anti-metastatic gene, plays a role in the invasiveness of gastric cancer cells. Using a tissue chip technology and immunohistochemistry, we demonstrated that NME2 expression was associated with levels of differentiation of gastric cancer cells and their metastasis into the lymph nodes. When the NME2 gene product was over-expressed by ;in vitro stable transfection, cells from BGC823 and MKN45 gastric cancer cell lines had reduced rates of proliferation, migration, and invasion through the collagen matrix, suggesting an inhibitory activity of NME2 in the propagation and invasion of gastric cancer. NME2 could, therefore, severe as a risk marker for gastric cancer invasiveness and a potential new target for gene therapy to enhance or induce NME2 expression.

Regulatory functions of Nm23-H2 in tumorigenesis: insights from biochemical to clinical perspectives

Substantial effort has been directed at elucidating the functions of the products of the Nm23 tumor metastasis suppressor genes over the past two decades, with the ultimate goal of exploring their translational potentials in changing cancer patients' outcomes. Much attention has been focused on the better-known Nm23-H1, but despite having high sequence similarity, Nm23-H2 functions differently in many aspects. Besides acting as a metastasis suppressor, compelling data suggest that Nm23-H2 may modulate various tumor-associated biological events to enhance tumorigenesis in human solid tumors and hematological malignancies. Linkage to tumorigenesis may occur through the ability of Nm23-H2 to regulate transcription, cell proliferation, apoptosis, differentiation, and telomerase activity. In this review, we examine the linkages of Nm23-H2 to tumorigenesis in terms of its biochemical and structural properties and discuss its potential role in various tumor-associated events.

A splicing variant of NME1 negatively regulates NF-κB signaling and inhibits cancer metastasis by interacting with IKKβ

IKKβ functions as a principal upstream activator of the canonical NF-κB pathway by phosphorylating IκB, leading to its proteasomal degradation. Because IKKβ is considered a therapeutic target, understanding its regulation may facilitate the design of efficient regulators of this molecule. Here, we report a novel IKKβ-interacting molecule, NME1L, a splicing variant of the NME1 protein. NME1 has attracted attention in cancer research because of its antimetastatic activity and reduced expression in multiple aggressive types of cancer. However, the effect was just moderate but not dramatic in anti-cancer activities. We found that only NME1L interacts with IKKβ. Exogenous expression of NME1L resulted in a potent decrease in TNFα-stimulated NF-κB activation, whereas knockdown of NME1/NME1L with shRNA enhanced activity of NF-κB. NME1L down-regulates IKKβ signaling by blocking IKKβ-mediated IκB degradation. When NME1L was introduced into highly metastatic HT1080 cells, the mobility was efficiently inhibited. Furthermore, in a metastasis assay, NME1L-expressing cells did not colonize the lung. Based on these results, NME1L is a potent antimetastatic protein and may be a useful weapon in the fight against cancers.

A logistic regression model for predicting axillary lymph node metastases in early breast carcinoma patients

Nodal staging in breast cancer is a key predictor of prognosis. This paper presents the results of potential clinicopathological predictors of axillary lymph node involvement and develops an efficient prediction model to assist in predicting axillary lymph node metastases. Seventy patients with primary early breast cancer who underwent axillary dissection were evaluated. Univariate and multivariate logistic regression were performed to evaluate the association between clinicopathological factors and lymph node metastatic status. A logistic regression predictive model was built from 50 randomly selected patients; the model was also applied to the remaining 20 patients to assess its validity. Univariate analysis showed a significant relationship between lymph node involvement and absence of nm-23 (p = 0.010) and Kiss-1 (p = 0.001) expression. Absence of Kiss-1 remained significantly associated with positive axillary node status in the multivariate analysis (p = 0.018). Seven clinicopathological factors were involved in the multivariate logistic regression model: menopausal status, tumor size, ER, PR, HER2, nm-23 and Kiss-1. The model was accurate and discriminating, with an area under the receiver operating characteristic curve of 0.702 when applied to the validation group. Moreover, there is a need discover more specific candidate proteins and molecular biology tools to select more variables which should improve predictive accuracy.

Searching for consistently reported up- and down-regulated biomarkers in colorectal cancer: a systematic review of proteomic studies

The cumulative lifetime risk for the development of colorectal cancer in the general population is 6 %. In many cases, early detection by fecal occult blood test is limited regarding sensitivity. Therefore, there is an urgent need for improved diagnostic tests in colorectal cancer. The recent development of high-throughput molecular analytic techniques should allow the rapid evaluation of new diagnostic markers. However, researchers are faced with an overwhelming number of potential markers form numerous colorectal cancer protein expression profiling studies. To address the challenge, we have carried out a comprehensive systematic review of colorectal cancer biomarkers from 13 published studies that compared the protein expression profiles of colorectal cancer and normal tissues. A protein ranking system that considers the number of comparisons in agreement, total sample sizes, average fold-change and direction of differential expression was devised. We observed that some proteins were consistently reported by multiple studies as differentially expressed with a statistically significant frequency (P < 0.05) in cancer versus normal tissues comparison. Our systematic review method identified proteins that were consistently reported as differentially expressed. A review of the top four candidates revealed proteins described previously as having diagnostic value as well as novel candidate biomarkers. These candidates should help to develop a panel of biomarkers with sufficient sensitivity and specificity for the diagnosis of colorectal cancer in a clinical setting.

[NM23, an example of a metastasis suppressor gene]

Metastasis suppressor genes - unlike tumor suppressor genes - are defined by their capacity to control metastatic dissemination in vivo without affecting growth of the primary tumor. The first of these metastasis suppressor genes, NM23, was identified in 1988. Since then, expression of NM23 has been studied widely in human tumor cohorts, often with contradictory results. Not only is NM23 overexpressed in most human solid tumors when compared to healthy tissues, but also low expression of NM23 correlates with metastasis and poor clinical prognosis in the advanced stages of a number of epithelial cancer types, including melanoma, breast, colon, and liver carcinoma. This does not hold true, however, for other cancer types such as neuroblastoma and hematological malignancies, in which high NM23 expression correlates with more aggressive disease. Genetic alterations in the NM23 gene - loss of heterozygosity, spontaneous mutations and polymorphisms - are rarely found in tumors; thus, the metastatic potential of tumor cells is probably affected by NM23 protein levels. Three lines of evidence demonstrate the anti-metastatic activity of NM23: first, overexpression of NM23 in metastatic cell lines reduces their metastatic potential in xenograft models; second, the incidence of lung metastases is elevated in NM23 knockout mice prone to develop hepatocellular carcinoma, and, third, silencing NM23 by RNA interference confers a "metastatic phenotype" on non-invasive human epithelial liver and colon cancer cell lines. It appears that NM23 is crucial for inhibiting invasive migration, so acting at early stages of metastatic dissemination. The mechanistic basis of the metastasis suppressor function of NM23 and its regulated expression still remains obscure, however. Reactivation of expression of the endogenous NM23 gene in tumor cells, or stimulation of the pathways it controls, constitutes a promising avenue for anti-metastatic therapy.

NM23 protein expression in colorectal carcinoma using TMA (tissue microarray): association with metastases and survival

CONTEXT

NM23, a metastasis suppressor gene, may be associated with prognosis in patients with colorectal carcinoma.

OBJECTIVE

To analyze NM23 expression and its association with the presence of lymph node and liver metastases and survival in patients operated on for colorectal carcinoma.

METHODS

One hundred thirty patients operated on for colorectal carcinoma were investigated. Tissue microarray blocks containing neoplastic tissue and tumor-adjacent non-neoplastic mucosa were obtained and analyzed by immunohistochemical staining using a monoclonal anti-NM23 antibody. Immunohistochemical expression was assessed using a semiquantitative scoring method, counting the percentage of stained cells. The results were compared regarding morphological and histological characteristics of the colorectal carcinoma, presence of lymph node and liver metastases, tumor staging, and patient survival. Statistical analysis was performed using the Mann-Whitney test, the Kruskal-Wallis test and Fisher's exact test. Survival analysis was performed using the Kaplan-Meier method and the log-rank test.

RESULTS

NM23 expression was higher in colorectal carcinoma tissue than in adjacent non-neoplastic mucosa (P<0.0001). NM23 protein expression did not correlate with degree of cell differentiation (P = 0.57), vascular invasion (P = 0.85), lymphatic invasion (P = 0.41), perineural infiltration (P = 0.46), staging (P = 0.19), lymph node metastases (P = 0.08), or liver metastases (P = 0.59). Disease-free survival showed significant association (P = 0.01) with the intensity of NM23 protein immunohistochemical expression in colorectal carcinoma tissue, whereas overall survival showed no association with NM23 protein expression (P = 0.13).

CONCLUSIONS

NM23 protein expression was higher in neoplastic colorectal carcinoma tissue than in adjacent non-neoplastic mucosa, showing no correlation with morphological aspects, presence of lymph node or liver metastases, colorectal carcinoma staging, or overall survival. Disease-free survival was higher in patients with increased NM23 expression.

Implication of metastasis suppressor NM23-H1 in maintaining adherens junctions and limiting the invasive potential of human cancer cells

Loss of NM23-H1 expression correlates with the degree of metastasis and with unfavorable clinical prognosis in several types of human carcinoma. However, the mechanistic basis for the metastasis suppressor function of NM23-H1 is obscure. We silenced NM23-H1 expression in human hepatoma and colon carcinoma cells and methodologically investigated effects on cell-cell adhesion, migration, invasion, and signaling linked to cancer progression. NM23-H1 silencing disrupted cell-cell adhesion mediated by E-cadherin, resulting in β-catenin nuclear translocation and T-cell factor/lymphoid-enhancing factor-1 transactivation. Further, NM23-H1 silencing promoted cellular scattering, motility, and extracellular matrix invasion by promoting invadopodia formation and upregulating several matrix metalloproteinases (MMP), including membrane type 1 MMP. In contrast, silencing the related NM23-H2 gene was ineffective at promoting invasion. NM23-H1 silencing activated proinvasive signaling pathways involving Rac1, mitogen-activated protein kinases, phosphatidylinositol 3-kinase (PI3K)/Akt, and src kinase. Conversely, NM23-H1 was dispensable for cancer cell proliferation in vitro and liver regeneration in NM23-M1 null mice, instead inducing cellular resistance to chemotherapeutic drugs in vitro. Analysis of NM23-H1 expression in clinical specimens revealed high expression in premalignant lesions (liver cirrhosis and colon adenoma) and the central body of primary liver or colon tumors, but downregulation at the invasive front of tumors. Our findings reveal that NM23-H1 is critical for control of cell-cell adhesion and cell migration at early stages of the invasive program in epithelial cancers, orchestrating a barrier against conversion of in situ carcinoma into invasive malignancy.

Nuclear localization and intensity of staining of nm23 protein is useful marker for breast cancer progression

BACKGROUND

Breast cancer is the most common cause of cancer death in the western world. The expression differences of many proteins are associated with breast cancer progression or suppression. The purpose of the study was to determine the expression of nm23 protein in the invasion status and metastatic potential of breast cancer by using tissue microarray and to determine its role in breast cancer based on the expression of nm23 gene product.

METHOD

nm23 protein expression was examined by immunohistochemistry (IHC) using commercially available tissue microarray containing malignant and normal breast tissues from 216 patients.

RESULTS

a similar percentage of cases showed positive cytoplasmic/nuclear staining for nm23 in normal breast tissue (85.7%), primary breast carcinoma node negative (97.5%) and carcinoma with lymph node metastasis (92.1%). Nuclear localization of staining for nm23 protein was higher in infiltrating ductal carcinoma (IDC) node positive (24.3%) and in matched lymph mode metastasis (18.9%) compared to IDC node negative (4.9%). Strong intensity of cytoplasmic/nucleus staining was observed in IDC node negative (42.6%), in IDC node positive (57.1%), and Infiltrating lobular carcinoma (ILC) node negative (44%) compared to normal breast tissue (16.7%).

CONCLUSION

nm23 protein expression appears widely expressed in normal breast, early and advanced breast cancer stages. Interestingly our study found that strong staining intensity and nuclear localization of nm23 protein may prove to be a useful marker of breast cancer progression.

Nm23-H1 expression of metastatic tumors in the lymph nodes is a prognostic indicator of oral squamous cell carcinoma

We recently reported that low Nm23-H1 expression of primary oral squamous cell carcinoma (OSCC) was correlated with the occurrence of lymphatic metastasis. However, little is known about whether Nm23-H1 level of metastatic tumors in the cervical lymph nodes is reduced in comparison with primary oral cancers and its significance for patients' prognosis. By immunohistochemistry, we analyzed the Nm23-H1 expression in 52 pairs of OSCC specimens from primary oral cancers and their metastatic lymph nodes. Western blot analysis further confirmed the immunohistochemical interpretation. To verify the effects of Nm23-H1 on cell migration and invasion, we established several stable clones derived from a human OSCC cell line (SAS) by knockdown and overexpression. Wound-healing closure, transwell migration and invasion assays were performed to determine cell motility, migratory and invasive activities. Western blot analysis was carried out to evaluate cyclin A expression of OSCC cells with the altered Nm23-H1 levels following knockdown and overexpression. By immunohistochemistry, Nm23-H1 expression of metastatic lymph nodes was significantly lower than that of their primary oral cancers, supporting a role of Nm23-H1 in metastasis suppression. Negative Nm23-H1 interpretation of OSCC specimens, in either primary oral cancers or metastatic lymph nodes, indicated a poor survival outcome of patients. On the basis of in vitro studies of Nm23-H1 knockdown and overexpression, we demonstrated an inverse correlation between Nm23-H1 expression and the invasiveness of OSCC cells. Moreover, we observed the concomitant reduction in Nm23-H1 and cyclin A levels of metastatic tumors in both results of in vitro OSCC cells and ex vivo tumor specimens.

Nm23/NDP kinases in hepatocellular carcinoma

One of the most aggressive cancers is hepatocellular carcinoma, which is associated with a very poor patient outcome due to a high recurrence rate and metastatic spread. NM23, the first metastasis suppressor gene to be identified, has been widely studied in human cancers. However, conflicting results have been obtained depending on the tumor type and the evaluation protocol. The current knowledge of NM23 as a diagnostic and/or prognostic marker in hepatocellular carcinoma is reviewed herein. Most studies demonstrate an inverse association between the expression of NM23-H1 and the metastatic potential, which is not observed with the closely related NM23-H2 isoform. Transfection of metastatic hepatoma cells with NM23 reduced their metastatic potential, as for other tumor cell lines. The demonstration of a causative role of NM23 in metastatic dissemination in a mouse model of hepatocarcinoma suggests that hepatocarcinoma-derived cells could be good models for the analysis of the molecular mechanisms involved in NM23 action.

Survey of molecular profiling during human colon cancer development and progression by immunohistochemical staining on tissue microarray

AIM: To explore the molecular events taking place during human colon cancer development and progression through high-throughput tissue microarray analysis.

METHODS: We constructed two separate tissue microarrays containing 1.0 mm or 1.5 mm cylindrical samples acquired from 112 formalin-fixed and paraffin-embedded blocks, including carcinomas (n = 85), adenomatous polyps (n = 18), as well as normal para-cancerous colon tissues (n = 9). Immunohistochemical staining was applied to the analysis of the consecutive tissue microarray sections with antibodies for 11 different proteins, including p53, p21, bcl-2, bax, cyclin D1, PTEN, p-Akt1, β-catenin, c-myc, nm23-h1 and Cox-2.

RESULTS: The protein expressions of p53, bcl-2, bax, cyclin D1, β-catenin, c-myc, Cox-2 and nm23-h1 varied significantly among tissues from cancer, adenomatous polyps and normal colon mucosa (P = 0.003, P = 0.001, P = 0.000, P = 0.000, P = 0.034, P = 0.003, P = 0.002, and P = 0.007, respectively). Chi-square analysis showed that the statistically significant variables were p53, p21, bax, β-catenin, c-myc, PTEN, p-Akt1, Cox-2 and nm23-h1 for histological grade (P = 0.005, P = 0.013, P = 0.044, P = 0.000, P = 0.000, P = 0.029, P = 0.000, P = 0.008, and P = 0.000, respectively), β-catenin, c-myc and p-Akt1 for lymph node metastasis (P = 0.011, P = 0.005, and P = 0.032, respectively), β-catenin, c-myc, Cox-2 and nm23-h1 for distance metastasis (P = 0.020, P = 0.000, P = 0.026, and P = 0.008, respectively), and cyclin D1, β-catenin, c-myc, Cox-2 and nm23h1 for clinical stages (P = 0.038, P = 0.008, P = 0.000, P = 0.016, and P = 0.014, respectively).

CONCLUSION: Tissue microarray immunohistochemical staining enables high-throughput analysis of genetic alterations contributing to human colon cancer development and progression. Our results implicate the potential roles of p53, cyclin D1, bcl-2, bax, Cox-2, β-catenin and c-myc in development of human colon cancer and that of bcl-2, nm23-h1, PTEN and p-Akt1 in progression of human colon cancer.

Differential liver protein expression during schistosomiasis

The arrival of eggs in the liver during Schistosoma mansoni infection initiates a protective granulomatous response; however, as the infection progresses, this response results in chronic liver fibrosis. To better understand the impact of schistosomiasis on liver function, we used a proteomic approach to identify proteins whose expression was significantly altered in schistosome-infected mice 8 weeks postinfection. Identification of differentially expressed proteins by mass fingerprinting revealed that schistosome infection markedly reduced the abundance of proteins associated with several normal liver functions (i.e., citric acid cycle, fatty acid cycle, and urea cycle), while proteins associated with stress responses, acute phase reactants, and structural components were all significantly more abundant. The expression patterns of several immunity-related proteins (peroxiredoxin 1, arginase 1, and galectin 1) suggested that different protein forms are associated with schistosome infection. These findings indicate that acute schistosomiasis has a significant impact on specific liver functions and, moreover, that the alterations in specific protein isoforms and upregulation of unique proteins may be valuable as new markers of disease.

Increased lung metastasis in transgenic NM23-Null/SV40 mice with hepatocellular carcinoma

BACKGROUND

The metastasis-suppressing role of the NM23 gene in the metastatic spread of solid tumors is still debated. We examined the role of NM23 in tumor development and metastatic dissemination by using transgenic mice that lack mouse NM23 (NM23-M1) in two mouse models of hepatocellular carcinoma (HCC) that recapitulate all steps of tumor progression.

METHODS

We induced HCC in mice that contained (NM23-M1(+/+)) or lacked (NM23-M1(-/-)) NM23-M1 by diethylnitrosamine injection or by a crossing scheme that transferred a transgene that leads to liver expression of simian virus 40 large T antigen (ASV mice). We used microscopic examination and immunohistochemistry to analyze tumor progression. Expression of Nm23 protein isoforms (Nm23-M1 and Nm23-M2) and several tumor markers was analyzed in the primary tumor and in metastases by Western blotting. The statistical significance of differences in the incidence of Nm23-M2 overexpression in null mice relative to that in wild-type mice was tested by a one-sided Fisher's exact test. The statistical significance of differences in the incidence of metastases was examined using one-sided chi-square tests. All other statistical tests were two-sided.

RESULTS

In both models, Nm23-M1 and/or Nm23-M2 were overexpressed in the primary liver tumors compared with nontumor liver tissue; however, the lack of the NM23-M1 gene had no effect on primary tumor formation in either model. ASV mice developed pulmonary metastases that were positive for the Hep-Par 1 antibody, which recognizes a specific hepatocyte antigen, whereas the few pulmonary nodules that developed in diethylnitrosamine-injected mice were negative for this antigen. Statistically significantly more ASV/NM23-M1(-/-) mice than ASV/NM23-M1(+/+) mice developed lung metastases (69.2% versus 37.5%; difference = 31.7%, 95% confidence interval = 13.1% to 50.3%; P<.001). In ASV/NM23-M1(+/+) mice, immunohistochemical staining for Nm23-M1 was highly heterogeneous among the primary liver tumors, but weak or negative among lung metastases.

CONCLUSIONS

The lack of NM23-M1 expression promotes metastasis in the SV40 animal model of liver carcinogenesis.

nm23-H1 expression and loss of heterozygosity in colon adenocarcinoma

BACKGROUND

The discovery that genetic alterations in oncogenes and tumour suppressor genes accompany tumour formation in many human tumours has encouraged the search for genes that promote or suppress tumour spread and metastasis; nm23 is a promising candidate for a metastasis suppressing gene.

AIMS

To evaluate whether expression of nm23-H1 protein or loss of heterozygosity (LOH) of the nm23-H1 gene is associated with colon cancer progression.

MATERIALS/METHODS

Paraffin wax embedded tissue sections were analysed immunohistochemically. DNA isolated from normal and tumour tissue was used for LOH analysis using a variable nucleotide tandem repeat (VNTR) marker located in the untranslated 5' region of the nm23-H1 gene. RNA isolated from tumour and normal tissue was used for "real time" RT-PCR.

RESULTS

Of 102 adenocarcinomas examined, 58.8% stained weakly for nm23-H1 protein. There was a negative correlation between nm23-H1 positivity and tumour histological grade. In VNTR analysis, 70.2% of patients were informative and 27.4% of tumours had nm23-H1 LOH. There was a positive correlation between nm23-H1 LOH and both tumour histological grade and Dukes's stage. Expression of nm23-H1 mRNA was increased in 22 of 30 colon tumours compared with normal tissue. No significant correlation was found between nm23-H1 mRNA expression and histological grade or Dukes's stage of tumours.

CONCLUSIONS

These findings suggest that nm23-H1 protein expression in early stages may have a role in suppressing metastasis in sporadic colon cancer, whereas at a later stage both reduced nm23-H1 protein expression and LOH of the nm23-H1 gene may play role in colon cancer progression and metastasis.

Analysis of the autoantibody repertoire in Burkitt's lymphoma patients: frequent response against the transcription factor ATF-2

In the last few years, serological identification of tumour-associated antigens (TAAs) by recombinant cDNA expression cloning (SEREX) has enabled the mapping of humoral immune responses against TAAs in various types of cancer. The present paper describes the application of SEREX to Burkitt's lymphoma (BL), a malignancy not previously characterized by SEREX. By using a cDNA library from a BL cell line that does not express IgG, technical difficulties related to background immunoglobulin clones were overcome. Screening with sera from three BL patients revealed immunoreactivity against seven different gene products, six of which represent known human genes. Five proteins had previously been characterized by SEREX in other malignancies or identified as targets of autoantibodies in autoimmune disease. Seroreactivity against ATF-2, a member of the AP-1 transcription factor family, was validated by enzyme-linked immunosorbent assay (ELISA) and Western blot analysis using recombinant ATF-2 protein. Autoantibody responses against ATF-2 were detected by ELISA in 6 of 8 BL patients, compared with 6 of 13 patients with T-cell non-Hodgkin's lymphoma (T-NHL), 5 of 23 patients with follicular lymphoma and 2 of 27 diffuse large B-cell lymphoma patients. In contrast, reactivity was found in only 1 of 50 healthy volunteers. Next, we showed by immunohistochemistry that the activated form of ATF2 (ATF-2pp) was highly expressed in six different BL samples. We conclude that the SEREX approach with a B-cell cDNA source is applicable in NHL. Furthermore, we identified genes with possible involvement in the pathogenesis of BL using this technique.

Systematic review of genetic influences on the prognosis of colorectal cancer

Background

In terms of genetics, colorectal cancer is one of the best understood of all malignant diseases. Genetic influences on prognosis may have far-reaching implications, especially for the design of surgical and chemoradiotherapeutic regimens. However, their significance in determining prognosis remains unclear. This study aimed to review the literature on the specific role of key genes in determining the survival of patients with colorectal cancer.

Methods

A Medline search was carried out to identify all original scientific papers relating colorectal cancer genetics to patient survival, up to December 2002. Cochrane and Embase databases were also searched. Identified articles were retrieved and searched carefully for additional information. This review includes K-ras, p53, DCC, NM23 and DNA mismatch repair genes.

Results and conclusion

Conflicting evidence exists as to the prognostic significance of genes commonly implicated in the pathogenesis of colorectal carcinoma. Possible causes for such discrepancy include differences in study methods and laboratory techniques, variable duration of follow-up, statistical differences in study power, and heterogeneity in study populations. Future studies should adopt standardized protocols to define clinically relevant genetic observations.

Integrative analysis of cancer‐related data using CAP

The development of human cancer is a highly complex process and can be considered the result of several combined events, such as genetic alterations, disturbance of signal transduction, or failure of immunological surveillance. Cancer-related databases usually focus on specific fields of research, e.g., cancer genetics or cancer immunology, whereas the complexity of cancer genesis requires an integrated analysis of heterogeneous data from several sources. Here we present the cancer-associated protein database (CAP), a novel analysis system for cancer-related data. CAP integrates data from multiple external databases, augments these data with functional annotations, and offers tools for statistical analysis of these data. We have employed CAP to analyze genes that have been found to cause an autoimmune response in cancer. In particular, we explored the connection between the autoimmune response, mutations, and overexpression of these genes. Our preliminary results suggest that mutations are not significant contributors to raising an antibody response against tumor antigens, whereas overexpression seems to play a more important role. We hereby demonstrate how different types of data can be integrated and analyzed successfully, providing interesting results. As the amount of available data is growing rapidly, a combined analysis will play an important role in exploring the genetic and immunological basis of cancer. CAP is freely available at the following web site: http://www.bioinf.uni-sb.de/CAP/.

Proteome analysis reveals novel proteins associated with proliferation and differentiation of the colorectal cancer cell line Caco-2

Here, we describe a proteomics approach to study protein expression changes in differentiating Caco-2 cells. Caco-2 is a colorectal carcinoma cell line, which upon differentiation loses its tumorigenic phenotype and displays characteristics of mature enterocytes, including brush borders with microvilli. Cells were grown in culture flasks and harvested at different stages of differentiation (days post-confluence: -3, 0, 3, 7, 10, 14, and 18). Two-dimensional gel electrophoresis was used to analyse proteome changes. Approximately 1400 protein spots were detected within the Caco-2 proteome, within the pH 4-7 range. Two-dimensional gel electrophoresis allowed for the detection of 18 proteins from which the levels of expression were found to be associated with differentiation. Of these proteins, 11 were identified by means of MALDI-TOF or NANO-ESI-MS/MS mass spectrometry and include liver fatty acid binding protein (FABL), three forms of alpha-enolase (ENOA), nucleoside diphosphate kinase A (NDKA), cofilin-1 (COF1), translationally controlled tumour protein (TCTP), mitochondrial 60-kDa heat shock protein (CH60), probable protein disulfide isomerase (ER60), creatine kinase B (KCRB), and glutathione S-transferase alpha (GTA1). Thus, proteomics revealed that the differentiation-related change in phenotype of Caco-2 involves changes in a variety of distinct biochemical pathways. Some of these proteins have not been shown before to be associated with Caco-2 differentiation (ER60; COF1; CH60; NDKA; TCTP and ENOA). Therefore, processes related to protein folding and disulfide bridge formation, cytoskeleton formation and maintenance, nucleotide metabolism, glycolysis as well as tumorigenesis-associated proteins may be involved in Caco-2 differentiation. Changes in the expression of CH60, TCTP, GTA1, NDKA, and FABL have also been reported to be associated with in vivo colon carcinogenesis. These findings illustrate that a combination of proteomics and cell culture is a useful approach to find markers for Caco-2 differentiation, which could contribute to the comprehension of the process of colon carcinogenesis.

Analysis of Both NM23-H1 and NM23-H2 Expression Identifies “At-Risk” Patients with Colorectal Cancer

Metastasis is the manifestation most directly affecting survival for patients with colorectal carcinoma. Identification of high-risk markers for metastases would allow focused selection of patients for adjuvant chemotherapy. Reports of the relationship between the putative metastasis suppressor NM23 and metastasis and/or survival in colorectal cancer patients are conflicting. The purpose of this study was to separately assess expression of NM23-H1 and NM23-H2 in primary colon cancers and determine whether expression was associated with regional nodal disease and/or liver metastases. Four patient cohorts were selected on the basis of histopathological staging at primary surgery (lymph node status/liver metastasis): -/- (n = 46), +/- (n = 47), -/+ (n = 43), and +/+ (n = 46). Primary tumors were evaluated by semiquantitative immunohistochemical analysis of NM23-H1 and NM23-H2. NM23-H2 expression was not related to survival; however, there was a modest survival advantage with low expression of NM23-H1 ( P = 0.027). NM23-H1 expression in the +/+ group was increased compared with the other groups ( P < 0.001). The -/+ group had the lowest expression of NM23-H2 ( P < 0.001). This analysis distinguishes two high-risk groups of colorectal cancer patients. Prior discrepancies regarding the usefulness of NM23 staining may be explained by the need to evaluate both serotypes in addition to standard histopathological analysis to identify specific “at-risk” groups.

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.

What we could do now: molecular pathology of colorectal cancer

The contribution of molecular genetics to colorectal cancer has been largely restricted to relatively rare inherited tumours and to the detection of germ line mutations predisposing to these cancers. However, much is now known about the somatic events leading to colorectal cancer in general. Several studies have examined the relation between genetic features and prognosis. The purpose of this article is to review these studies and summarise the current state of this subject. Although many of the published studies are small and inconclusive, it is clear that several different pathways exist for the development of this cancer, and some molecular characteristics seem to correlate with clinicopathological features. At present, studies are confined to evaluating a small number of molecular markers; however, with the advent of methods for the rapid genetic profiling of large numbers of colorectal cancers, it will be possible to evaluate fully the clinical usefulness of a range of colorectal cancer genotypes.

nm23 protein expression in colorectal carcinoma metastasis in regional lymph nodes and the liver

AIMS

The nm23 gene has been shown to have metastasis suppressing activity and abnormalities of the gene or its expression may be important in tumour progression and dissemination. This study was set out to investigate the possible role of the nm23 in colorectal adenocarcinoma dissemination by examining the level of nm23 protein expression in colorectal carcinoma metastasis in regional lymph nodes and the liver.

METHODS

Using a monoclonal antibody, NCL-nm23 (Novocastra), immunohistochemical expression of the nm23 protein was examined in cases of metastatic colorectal adenocarcinoma in regional lymph nodes (n=71) and liver (n=36).

RESULTS

The cases of lymph-node metastasis also had tissues from the primary carcinoma (n=71) and matching normal non-neoplastic mucosal tissues (n=71) from the colon and rectum available for the study. More than half of the cases of primary colorectal carcinoma (43/71; 60%) displayed strong nm23 immunoreactivity, with a similar proportion of the lymph-node metastases (40/71 cases; 56%) having strong nm23 immunostaining. However, only a small minority of the normal controls of non-neoplastic colorectal epithelia (12/71 cases; 17%) had strong nm23 immunoreactivity. The difference in nm23 protein expression between normal colorectal mucosa and primary colorectal carcinoma was statistically significant (P=0.0001; chi-squared test with continuity correction). However, no significant difference in nm23 protein expression was found between primary colorectal carcinoma and lymph-node metastases (P=0.81; chi-squared test with continuity correction). Most of the liver metastases (24/36 cases; 67%) had strong nm23 immunostaining but this finding was not statistically significant when compared with that seen in primary colorectal carcinoma (P=0.62; chi-squared test with continuity correction). In addition, nm23 expression was not found to significantly correlate with 5-year survival of patients with liver metastasis (P=0.86), suggesting that it had no predictive value for overall patient survival. There was also no significant correlation between disease recurrence and nm23 expression (P=0.63).

CONCLUSIONS

In summary, increased nm23 protein immunoreactivity is seen in the majority of colorectal carcinomas when compared to normal colorectal tissues but no significant difference in nm23 expression was found between primary colorectal carcinoma and metastatic carcinoma in regional lymph nodes or the liver. This study suggests that increased nm23 expression may be important in early colorectal carcinoma but not in later progression and dissemination of the tumour. In conclusion, the role and importance of the nm23 gene in the development of tumour metastasis in colorectal carcinoma is questionable.

Reappraisal of the role of NM23-H1 in colorectal cancers

BACKGROUND AND OBJECTIVES

A number of evidence indicate that downregulation of the nm23-H1 gene may be relevant to metastatic progression of many kinds of human cancer. However, its role in colorectal cancers remains controversial. To address the issue, this study was performed to investigate the clinical relevance of nm23-H1 in patients with colorectal cancers.

METHODS

Immunohistochemical expression of nm23-H1 protein product (NM23-H1) was studied in a total of 146 colorectal cancer patients and compared for its prognostic value at a mean follow-up of 54 months.

RESULTS

There was no apparent correlation between NM23-H1 expression and clinicopathological indicators, including Dukes category, lymphatic metastasis, distant metastasis, histological grading, and tumor location (P < 0.1, respectively). In addition, determination of NM23-H1 expression status did not provide independent prognostic information compared with conventional pathological staging.

CONCLUSIONS

The results indicate that nm23-H1 gene does not play an important part in the progression of colorectal carcinogenesis.

nm23: unraveling its biological function in cell differentiation

Tumor suppressor genes have a pivotal role in normal cells regulating cell cycle processes negatively. Furthermore, the inhibition of cell proliferation is a crucial step in the achievement of cell differentiation. Increasing evidence suggests that the nm23 genes, initially documented as suppressors of the invasive phenotype in some cancer types, are involved in the control of normal development and differentiation. In this review, we summarize some data concerning the involvement of the nm23 genes in development and differentiation, attempting to delineate an overall view of many facets of their biological role.

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.

Genetic pathways in colorectal and other cancers

Cells from cancers show aberrant behaviour such as unrestrained growth, invasion into adjacent tissue and metastasis. All these features of cancer cell behaviour can be explained in terms of genetic changes and the functional impact of these changes. In this review, colorectal cancer (CRC) is examined as a classical example of multistep carcinogenesis. First there is an overview which shows that cancers develop by a process of somatic evolution. This gives rise to preferred genetic pathways of tumorigenesis. The factors which may influence the development and ultimate choice of genetic pathways are then examined. Next, CRC is studied as a specific disease and the putative genetic pathways are described. The mutations that comprise these pathways and the possible functional sequelae of these are explored. The review concludes with a look at those avenues which may further elucidate the natural history of CRC and lead to improved therapy.

Cleavage of DNA by human NM23-H2/nucleoside diphosphate kinase involves formation of a covalent protein-DNA complex

The NM23 gene family in humans is implicated in differentiation and cancer, but the biochemical mechanisms are unknown. Most NM23 proteins have phosphotransferase (nucleoside diphosphate kinase) activity, and the second human isoform, NM23-H2, also binds to a nuclease-hypersensitive c-MYC promoter element through which it activates c-MYC transcription. It is shown here that this DNA binding can result in double-stranded breaks. The DNA breaks occur within repeated sequence elements in the linear nuclease-hypersensitive duplex and leave staggered ends with 5-nucleotide-long 3'-extensions. The enzyme also cleaves supercoiled plasmid DNA to yield nicked circular and unit length linear products. The cleavage reaction requires only NM23-H2, DNA, Mg(2+), and buffer, occurs in the absence of denaturing conditions, and can be reversed by EDTA. The cleaved DNA strands have free 3'-OH groups, and protein is attached to the 5'-phosphoryl ends. Transfer of (32)P radioactivity from DNA to NM23-H2 has been observed, and a covalent polypeptide-DNA complex has been isolated and identified by Western blotting as NM23-H2. Since covalent protein-DNA complexes are known to serve the role of breaking and rejoining DNA strands, the present findings suggest that NM23-H2 is involved in DNA structural transactions necessary for the activity of the c-MYC promoter.

Genetic pathways in colorectal and other cancers

Cells from cancers show aberrant behaviour such as unrestrained growth, invasion into adjacent tissue and metastasis. All these features of cancer cell behaviour can be explained in terms of genetic changes and the functional impact of these changes. In this review, colorectal cancer (CRC) is examined as a classical example of multistep carcinogenesis. First there is an overview which shows that cancers develop by a process of somatic evolution. This gives rise to preferred genetic pathways of tumorigenesis. The factors which may influence the development and ultimate choice of genetic pathways are then examined. Next, CRC is studied as a specific disease and the putative genetic pathways are described. The mutations that comprise these pathways and the possible functional sequelae of these are explored. The review concludes with a look at those avenues which may further elucidate the natural history of CRC and lead to improved therapy.

Cytoskeletal association of the A and B nucleoside diphosphate kinases of interphasic but not mitotic human carcinoma cell lines: specific nuclear localization of the B subunit

The human A and B subunits of nucleoside diphosphate kinase (NDP kinase), encoded by the nm23-H1 and nm23-H2 genes, respectively, associate as homo- or heterohexamers to be catalytically active for the synthesis of nucleoside triphosphates. Despite 88% identity, they appear to possess specific functions. The nm23-H1 gene is implicated in tumor progression and metastasis, and the nm23-H2 gene product is a transcription factor for c-myc. To determine if these distinct functions reflect different subcellular localizations, the distribution of the A and B NDP kinases was analyzed by immunocytofluorescence microscopy in human breast cancer cell lines (MCF-7 and MDA-MB-231) using highly specific polyclonal and monoclonal antibodies. Interphasic cells exhibited a granular and filamentous cytoplasmic staining, particularly intense around nuclei, with both anti-NDP kinase A and B antibodies. The filamentous component observed with either anti-A or anti-B antibodies was altered in parallel to tubulin labeling with compounds interacting with microtubules, such as taxol and colchicine. Confirming published biochemical data, a partial colocalization with the vimentin network was observed in the MDA-231 cell line. A nuclear and nucleolar localization of NDP kinase B was shown by confocal microscopy which was not observed with the A enzyme. In dividing cells, NDP kinase labeling was punctiform and was not colocalized with the mitotic spindle. In conclusion, the A and B NDP kinases are similarly distributed in cytosol, associated partly to microtubules supporting a role in nucleotide channeling. Only the B enzyme is present in nuclei in accord with its role as a DNA binding protein. Their altered localization in dividing cells suggests colocalization with yet unidentified structures which are not intermediate filament aggregates.

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.