The potential roles of nm23 in cancer metastasis and cellular differentiation

Inhibitor of DNA Binding 2 (ID2): A Novel Marker for Lymph Node Metastasis in Head and Neck Squamous Cell Carcinoma

BACKGROUND

Although aggressive invasion and sequential lymph node metastasis (LNM) significantly affect the prognosis of patients with head and neck squamous cell carcinoma (HNSCC), studies on identifying the factors that regulate this process remain scarce. This study found an inhibitor of DNA binding 2 (ID2) as a novel molecule involved in the regulation of invasion and LNM of HNSCC and further verified its functional role.

METHODS

The study examined the translational significance between ID2 expression levels and the presence of LNM as well as the prognosis for 119 patients with HNSCC after treatment. In addition, in vitro and in vivo experiments were performed using ID2 gene-modulated HNSCC cell lines to determine the functional role of ID2 in the invasion and LNM of HNSCC.

RESULTS

Elevated levels of ID2 expression were closely associated with the presence of LNM in 119 patients with HNSCC, resulting in a poor prognosis. Overexpression of ID2-induced invasion and LNM of HNSCC cells was observed in vitro and in vivo. By contrast, knockdown of the ID2 gene diminished invasion and LNM of HNSCC cells. In addition, the ID2 expression level increased the expression level of matrix metalloproteinase 1 (MMP1), a molecule downstream to ID2. Furthermore, silencing of MMP1 in ID2-overexpressed HNSCC cells rescued the elevated invasion and LNM capabilities of these cells, suggesting that ID2 enhances invasion and LNM partly via MMP1 activation.

CONCLUSION

In the invasion and LNM of HNSCC, ID2 plays an important role by modulating MMP1 expression, suggesting ID2-MMP1 axis to be a novel alternative therapeutic target for invasion and LNM of HNSCC.

Compression of quantification uncertainty for scRNA-seq counts

Motivation

Quantification estimates of gene expression from single-cell RNA-seq (scRNA-seq) data have inherent uncertainty due to reads that map to multiple genes. Many existing scRNA-seq quantification pipelines ignore multi-mapping reads and therefore underestimate expected read counts for many genes. alevin accounts for multi-mapping reads and allows for the generation of ‘inferential replicates’, which reflect quantification uncertainty. Previous methods have shown improved performance when incorporating these replicates into statistical analyses, but storage and use of these replicates increases computation time and memory requirements.

Results

We demonstrate that storing only the mean and variance from a set of inferential replicates (‘compression’) is sufficient to capture gene-level quantification uncertainty, while reducing disk storage to as low as 9% of original storage, and memory usage when loading data to as low as 6%. Using these values, we generate ‘pseudo-inferential’ replicates from a negative binomial distribution and propose a general procedure for incorporating these replicates into a proposed statistical testing framework. When applying this procedure to trajectory-based differential expression analyses, we show false positives are reduced by more than a third for genes with high levels of quantification uncertainty. We additionally extend the Swish method to incorporate pseudo-inferential replicates and demonstrate improvements in computation time and memory usage without any loss in performance. Lastly, we show that discarding multi-mapping reads can result in significant underestimation of counts for functionally important genes in a real dataset.

Availability and implementation

makeInfReps and splitSwish are implemented in the R/Bioconductor fishpond package available at https://bioconductor.org/packages/fishpond. Analyses and simulated datasets can be found in the paper’s GitHub repo at https://github.com/skvanburen/scUncertaintyPaperCode.

Supplementary information

Supplementary data are available at Bioinformatics online.

Anti-tumor peptide SA12 inhibits metastasis of MDA-MB-231 and MCF-7 breast cancer cells via increasing expression of the tumor metastasis suppressor genes, CDH1, nm23-H1 and BRMS1

In recent years, there has been progress in the treatment of breast cancer; however, the prognosis is still poor due to recurrence and metastasis following conventional treatment. The anti-tumor peptide SA12 has been demonstrated to inhibit proliferation and arrest the cell cycle in MDA-MB-231 and MCF-7 breast cancer cells. In the present study, whether SA12 was able to inhibit the metastasis of breast cancer cells was investigated. Wound healing and Transwell assays were used to investigate the inhibition of SA12 on cell migration while, reverse transcription-quantitative PCR and western blot assays were used to identify the mechanism of action behind the effects of SA12 on cell migration. Results from the wound healing and Transwell assays revealed that SA12 significantly inhibited the migration of MDA-MB-231 and MCF-7 breast cancer cells following treatment with 100 µM SA12. Compared with that in the controls, the mRNA expression levels of cadherin 1 (CDH1), non-metastasis 23-H1 (nm23-H1) and breast cancer metastasis suppressor 1 (BRMS1) were increased in MDA-MB-231 and MCF-7 cells following treatment with 100 µM SA12. Furthermore, the protein expression levels of E-cadherin, NM23A and BRMS1 were also increased in MDA-MB-231 cells and MCF-7 cells following treatment with 100 µM SA12. In conclusion, SA12 inhibited the migration of MDA-MB-231 and MCF-7 breast cancer cells and enhanced the expression of the tumor metastasis suppressor genes, CDH1, nm23-H1 and BRMS1, which may be responsible for the SA12-induced inhibition of breast cancer cell metastasis.

Small Molecules as Drugs to Upregulate Metastasis Suppressors in Cancer Cells

It is well-recognized that the majority of cancer-related deaths is attributed to metastasis, which can arise from virtually any type of tumor. Metastasis is a complex multistep process wherein cancer cells must break away from the primary tumor, intravasate into the circulatory or lymphatic systems, extravasate, proliferate and eventually colonize secondary sites. Since these molecular processes involve the coordinated actions of numerous proteins, targeted disruptions of key players along these pathways represent possible therapeutic interventions to impede metastasis formation and reduce cancer mortality. A diverse group of proteins with demonstrated ability to inhibit metastatic colonization have been identified and they are collectively known as metastasis suppressors. Given that the metastasis suppressors are often downregulated in tumors, drug-induced re-expression or upregulation of these proteins represents a promising approach to limit metastasis. Indeed, over 40 compounds are known to exhibit efficacy in upregulating the expression of metastasis suppressors via transcriptional or post-transcriptional mechanisms, and the most promising ones are being evaluated for their translational potentials. These small molecules range from natural products to drugs in clinical use and they apparently target different molecular pathways, reflecting the diverse nature of the metastasis suppressors. In this review, we provide an overview of the different classes of compounds known to possess the ability to upregulate one or more metastasis suppressors, with an emphasis on their mechanisms of action and therapeutic potentials.

Identification of a gene expression signature associated with the metastasis suppressor function of NME1: prognostic value in human melanoma

Although NME1 is well known for its ability to suppress metastasis of melanoma, the molecular mechanisms underlying this activity are not completely understood. Herein, we utilized a bioinformatics approach to systematically identify genes whose expression is correlated with the metastasis suppressor function of NME1. This was accomplished through a search for genes that were regulated by NME1, but not by NME1 variants lacking metastasis suppressor activity. This approach identified a number of novel genes, such as ALDOC, CXCL11, LRP1b, and XAGE1 as well as known targets such as NETO2, which were collectively designated as an NME1-Regulated Metastasis Suppressor Signature (MSS). The MSS was associated with prolonged overall survival in a large cohort of melanoma patients in The Cancer Genome Atlas (TCGA). The median overall survival of melanoma patients with elevated expression of the MSS genes was >5.6 years longer compared with that of patients with lower expression of the MSS genes. These data demonstrate that NMEl represents a powerful tool for identifying genes whose expression is associated with metastasis and survival of melanoma patients, suggesting their potential applications as prognostic markers and therapeutic targets in advanced forms of this lethal cancer.

RGS19 upregulates Nm23-H1/2 metastasis suppressors by transcriptional activation via the cAMP/PKA/CREB pathway

The Nm23 metastasis suppressor family is involved in physiological and pathological processes including tumorigenesis and metastasis. Although the inverse correlation of Nm23 level with tumor metastasis potential has been widely observed, the mechanisms that regulate the expression of Nm23 remain poorly understood. Our previous studies have revealed that Nm23-H1/2 isoforms are upregulated by RGS19, a regulator of G protein signaling (RGS) protein which accelerates the termination of G_i signals. Here, we examined the ability of RGS19 to stimulate transcriptional regulation of Nm23 by screening a panel of luciferase reporter genes. Transient and stable overexpression of RGS19 upregulated the Nm23-H1/2 protein levels and activated several transcription factors including CREB, AP-1 and SRE in HEK293 cells. Interestingly, agents that increase the intracellular cAMP level and the phosphorylation of CREB (e.g., adrenergic receptor agonist, forskolin, and cAMP analogues) upregulated the expression of Nm23-H1/2 in HEK293 cells and several cancer cell lines including A549, HeLa, MDA-MB-231, and MDA-MB-435s cells. Conversely, inhibition of protein kinase A (PKA) by H-89 suppressed the phosphorylation of CREB and reduced the expression of Nm23-H1/2. Furthermore, activation of PKA attenuated cancer cell migration in wound healing and transwell assays. Collectively, these results revealed a PKA-dependent mechanism for controlling Nm23-H1/2 expression.

Differential regulation of NM23-H1 under hypoxic and serum starvation conditions in metastatic cancer cells and its implication in EMT

Multiple stresses are prevalent inside the tumor microenvironment rendering tumor growth, neighboring invasion and metastasis of the cancer cells to distant organs. NM23-H1 is the first metastasis suppressor gene identified and known to be implicated as an important regulator of stress-induced metastasis. Herein, we demonstrated that prototypical NM23-H1 expression diminished during hypoxia and serum starvation in Panc-1/MDA-MB-231 cells, but converse invasion patterns were obtained in these two diverse stresses. Supportingly, a compelling discrete difference in mRNA and protein levels of NM23-H1 was achieved in hypoxia as well as serum starvation. Knockdown of NM23-H1 activates EMT whereas the similar effects are subdued in serum starvation where NM23-H1 down-modulation prompted E-cadherin upregulation. Stable NM23-H1 expression augmented E-cadherin levels along with retardation in invadopodea formation and invasion. In hypoxia/serum starvation excess NM23-H1 effectively modulated the Twist1 promoter activity. Thus, differential regulation of NM23-H1 may corroborate/abrogate EMT depending on the nature of stress, tumor microenvironment and cellular context.

Extracellular NM23 Protein as a Therapeutic Target for Hematologic Malignancies

An elevated serum level of NM23-H1 protein is a poor prognostic factor in patients with various hematologic malignancies. The extracellular NM23-H1 protein promotes the in vitro growth and survival of acute myelogenous leukemia (AML) cells and inversely inhibits the in vitro survival of normal peripheral blood monocytes in primary culture at concentrations equivalent to the levels found in the serum of AML patients. The growth and survival promoting activity to AML cells is associated with cytokine production and activation of mitogen-activated protein kinases (MAPKs) and signal transducers and activators of transcription (STAT) signaling pathways. Inhibitors specific for MAPK signaling pathways inhibit the growth/survival-promoting activity of NM23-H1. These findings indicate a novel biological action of extracellular NM23-H1 and its association with poor prognosis. These results suggest an important role of extracellular NM23-H1 in the malignant progression of leukemia and a potential therapeutic target for these malignancies.

Expression of nm23-H1 is associated with poor prognosis in peripheral T-cell lymphoma, not otherwise specified

PURPOSE

We examined whether nm23-H1 is a prognostic factor of peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS).

EXPERIMENTAL DESIGN

We studied 102 consecutive, untreated PTCL-NOS patients from 1998 to 2008. The expression of nm23-H1 and TIA-1 was studied by immunohistochemistry.

RESULTS

nm23-H1 was positive in 44.1% and TIA-1 in 78.4% of the PTCL-NOS patients. nm23-H1 expression was not correlated with age, performance status (PS), lactate dehydrogenase (LDH) level, or stage but was significantly correlated with the prognostic index for T-cell lymphoma. The serum nm23-H1 level was 43.44 ng/mL in the cytoplasmic nm23-H1 strongly positive, 24.32 ng/mL in the cytoplasmic nm23-H1 moderately positive, and 13.64 ng/mL in the cytoplasmic nm23-H1-negative patients. The nm23-H1-positive group had significantly shorter overall survival (OS). TIA-1 had no prognostic impact on 5-year OS rates. OS was significantly shorter in patients with the following clinicopathologic features: age 60 or more years, PS of 2 to 4, LDH level greater than normal, bone marrow involvement, or nm23-H1-positive lymphoma. Multivariate analysis confirmed nm23-H1 expression to be an independent prognostic factor.

CONCLUSIONS

The nm23-H1 protein may be an important prognostic factor in PTCL-NOS. Because our results suggested that nm23-HI is produced by lymphoma cells, we expect to see the development of new treatments targeting nm23 overexpression.

Prognostic biomarkers in squamous cell carcinoma of the anus: a systematic review

BACKGROUND

recent decades have seen combination chemoradiotherapy become the standard treatment for anal squamous cell carcinoma (SCC). However, the burden of this disease continues to rise, with only 10% of patients with metastatic disease surviving >2 years. Further insight into tumour characteristics and molecular biology may identify novel therapeutic targets. This systematic review examines current prognostic markers in SCC of the anus.

METHODS

an extensive literature search was performed to identify studies reporting on biomarkers in anal cancer in the context of clinical outcome following treatment primarily with chemoradiotherapy.

RESULTS

in all, 21 studies were included. A total of 29 biomarkers were studied belonging to 9 different functional classes. Of these biomarkers, 13 were found to have an association with outcome in at least one study. The tumour-suppressor genes p53 and p21 were the only markers shown to be of prognostic value in more than one study.

CONCLUSIONS

an array of biomarkers have been identified that correlate with survival following chemoradiotherapy in anal cancer. However, investigators are yet to identify a biomarker that has the ability to consistently predict outcome in this disease. Further studies are needed to elucidate whether these candidate biomarkers demonstrate their optimum value when they serve as targets for new therapeutic strategies.

Extracellular NM23 protein promotes the growth and survival of primary cultured human acute myelogenous leukemia cells

An elevated serum level of NM23-H1 protein is found in acute myelogenous leukemia (AML), and predicts a poor treatment outcome in AML patients. To investigate the potential pathological link between the elevated serum level of this protein and poor prognosis, we examined the extracellular effects of recombinant NM23-H1 protein on the in vitro growth and survival of primary cultured AML cells at concentrations equivalent to the levels found in the serum of AML patients. Extracellular NM23-H1 protein promoted the in vitro growth and survival of AML cells and this activity was associated with the cytokine production and activation of the MAPK and signal transducers and activators of transcription signaling pathways. Inhibitors specific to MAPK signaling pathways inhibited the growth- and survival-promoting activity of NM23-H1. These findings indicate the novel biological action of extracellular NM23-H1 and its association with poor prognosis, and suggest an important role for extracellular NM23-H1 in the malignant progression of leukemia and a potential therapeutic target for these malignancies.

Extracellular NM23-H1 protein inhibits the survival of primary cultured normal human peripheral blood mononuclear cells and activates the cytokine production

An elevated serum level of NM23-H1 protein is found in acute myelogenous leukemia (AML) and predicts a poor treatment outcome for AML patients. To investigate the potential pathological link between the elevated serum level of this protein and poor prognosis, we examined the extracellular effects of recombinant NM23-H1 protein on the in vitro survival of primary cultured normal peripheral blood mononuclear cells (PBMNC) at concentrations equivalent to the levels found in the serum of AML patients. Extracellular NM23-H1 protein inhibited the in vitro survival of PBMNC and promoted the production of various cytokines, such as GM-CSF and IL-1beta, which in fact promoted the growth of primary cultured AML cells. These findings indicate a novel biological action of extracellular NM23-H1 and its association with poor prognosis of patients with elevated serum levels of NM23-H1 protein. These results suggest an important role of extracellular NM23-H1 in the malignant progression of leukemia and a potential therapeutic target for these malignancies.

EBNA3C can modulate the activities of the transcription factor Necdin in association with metastasis suppressor protein Nm23-H1

Previous studies have demonstrated the interaction between the Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA3C) and the metastatic suppressor Nm23-H1 both in vitro and in vivo (C. Subramanian, M. A. Cotter II, and E. S. Robertson, Nat. Med. 7:350-355, 2001). Importantly EBNA3C can reverse the ability of Nm23-H1 to suppress migration of human cells in vitro. EBNA3C contributes to EBV-associated human cancers by regulating transcription of a number of cellular and viral promoters as well as targeting and altering the transcription activities of the metastasis suppressor Nm23-H1. Furthermore, Necdin is a cellular protein which is highly induced in terminally differentiated cells; it contributes to the regulation of cell growth and is also known to interact with viral oncoproteins. In this report, we show that Nm23-H1 and EBNA3C can modulate the biological functions of Necdin in the context of EBV infection and transformation. The levels of Necdin were consistently lower in EBV-positive cells, and EBNA3C could change the subcellular localization of Necdin as well as rescue cells from the antiangiogenic and antiproliferative effects mediated by Necdin. We also show that Necdin directly interacts with Nm23-H1, resulting in modulation of the biochemical function of Nm23-H1 as well as the biological function of Necdin. Both EBNA3C and Nm23-H1 were able to rescue not only Necdin-mediated transcriptional repression of the downstream vascular endothelial growth factor promoter but also Necdin-mediated growth suppression and antiangiogenic effects on cancer cells. The majority of this response was mediated through amino acid residues 191 to 222 of Necdin, which are also known to be important for nuclear matrix targeting. These studies suggest a role for Necdin in the regulation of downstream cellular targets in a hypoxic environment in virus-associated human cancers.

nm23 protein expression in metastatic and non-metastatic tongue squamous cell carcinoma

Oral squamous cells carcinoma (OSCC) shows unfavorable prognosis due to its invasion potential around the neighboring tissues and the elevated incidence of metastasis.

Aim

the present paper aims at analyzing the immunohistochemical expression of the nm23 protein in metastatic and non-metastatic SCCs of tongue.

Methods

the immuno-expression to the nm23-hl protein was diagnosed in 35 tongue SCC (15 of which exhibiting metastasis). Nm23-hl immuno-scores were assigned as follow: score 0 = absent, 1 = focal and 2 = diffuse expression.

Results

The Fisher's exact test was performed and there was no statistical difference between the nm23-hl immuno-scores and the tongue SCCs studied cases (p=0.365), although 66.7% of metastatic cases presented negative nm23-hl expression.

Conclusions

Protein nm23 was not associated with a positiveness for tongue SCC without metastasis. Thus, several others factors inherent to host and malignancy can be associated with the mechanisms that suppress the metastatic process in this disease.

Drug development against metastasis-related genes and their pathways: a rationale for cancer therapy

It is well recognized that the majority of cancer related deaths is caused by metastatic diseases. Therefore, there is an urgent need for the development of therapeutic intervention specifically targeted to the metastatic process. In the last decade, significant progress has been made in this research field, and many new concepts have emerged that shed light on the molecular mechanism of metastasis cascade which is often portrayed as a succession of six distinct steps; localized invasion, intravasation, translocation, extravasation, micrometastasis and colonization. Successful metastasis is dependent on the balance and complex interplay of both the metastasis promoters and suppressors in each step. Therefore, the basic strategy of our interventions is aimed at either blocking the promoters or potentiating the suppressors in this disease process. Toward this goal, various kinds of antibodies and small molecules have been designed. These include agents that block the ligand-recepter interaction of metastasis promoters (HGF/c-Met), antagonize the metastasis-promoting enzymes (AMF, uPA and MMP) and inhibit the transcriptional activity of metastasis promoter (beta-Catenin). On the other hand, the intriguing roles of metastasis suppressors and their signal pathways have been extensively studied and various attempts have been made to potentiate these factors. Small molecules have been developed to restore the expression or mimic the function of metastasis-suppressor genes such as NM23, E-cadherin, Kiss-1, MKK4 and NDRG1, and some of them are under clinical trials. This review summarizes our current understanding of the molecular pathway of tumor metastasis and discusses strategies and recent development of anti-metastatic drugs.

Expressão da proteína nm23 em carcinoma de células escamosas de língua metastático e não-metastático

O carcinoma de células escamosas oral (CCEO) exibe prognóstico desfavorável em decorrência da capacidade de invasão aos tecidos vizinhos e elevada incidência de metástases. OBJETIVO: O presente trabalho objetiva analisar a expressão imunohistoquímica da proteína nm23 em CCEs de língua metastáticos e não-metastáticos. METODOLOGIA: A técnica da imunohistoquímica para a proteína nm23-h1 foi realizada em 35 casos de CCE de língua com metástase em 15 casos. Atribuiu-se escore 0, para ausência de marcação; 1, marcação focal e 2 para marcação difusa. RESULTADOS: Observou-se marcação focal para a proteína nm23 em 9 casos, difusa em 15, e ausência de marcação em 11 espécimes. O teste exato de Fischer foi aplicado, não havendo diferença estatisticamente significativa para positividade desta proteína nos casos metastáticos e não-metastáticos (p=0.365), apesar de que em 66.7% dos casos com metástase não houve marcação. CONCLUSÕES: A presença da proteína nm23 não esteve relacionada de forma positiva aos casos de CCE de língua sem metástase. Dessa forma, vários outros fatores inerentes à célula neoplásica e ao hospedeiro podem estar relacionados aos mecanismos supressores do processo metastático nesta entidade.

Expression of nm23 in the spectrum of pre-invasive, invasive and metastatic breast lesions

Background

Nm23 protein is a metastasis suppressor protein, expressed in all tissues. Reduced Nm23 expression is related to a high incidence of lymph node and distant metastasis and poor prognosis in patients with cancers. The present study was done to analyze the expression of Nm23 using immunohistochemistry in non-neoplastic and neoplastic breast lesions.

Methods

Sections from 93 samples were studied and classified into non-proliferative breast lesion (13), fibrodenoma (7), proliferative breast lesion (13), carcinoma in situ (20), invasive carcinoma (23) and metastatic deposits in lymph nodes (17).

Results

Nm23 expression in these groups showed a progressive down regulation with increasing neoplastic transformation. On comparing the various groups, nm23 expression was significantly different between the various subgroups with greatest expression in non-proliferative lesions and least in metastatic deposits (p < 0.050).

Conclusion

It is concluded that the modulation of nm23 in a spectrum of breast lesions can be indicative of metastatic phenotype and help to predict the aggressiveness of disease.

Emerging roles for protein histidine phosphorylation in cellular signal transduction: lessons from the islet beta-cell

Protein phosphorylation represents one of the key regulatory events in physiological insulin secretion from the islet β-cell. In this context, several classes of protein kinases (e.g. calcium-, cyclic nucleotide- and phospholipid-dependent protein kinases and tyrosine kinases) have been characterized in the β-cell. The majority of phosphorylated amino acids identified include phosphoserine, phosphothreonine and phosphotyrosine. Protein histidine phosphorylation has been implicated in the prokaryotic and eukaryotic cellular signal transduction. Most notably, phoshohistidine accounts for 6% of total protein phosphorylation in eukaryotes, which makes it nearly 100-fold more abundant than phosphotyrosine, but less abundant than phosphoserine and phosphothreonine. However, very little is known about the number of proteins with phosphohistidines, since they are highly labile and are rapidly lost during phosphoamino acid identification under standard experimental conditions. The overall objectives of this review are to: (i) summarize the existing evidence indicating the subcellular distribution and characterization of various histidine kinases in the islet β-cell, (ii) describe evidence for functional regulation of these kinases by agonists of insulin secretion, (iii) present a working model to implicate novel regulatory roles for histidine kinases in the receptor-independent activation, by glucose, of G-proteins endogenous to the β-cell, (iv) summarize evidence supporting the localization of protein histidine phosphatases in the islet β-cell and (v) highlight experimental evidence suggesting potential defects in the histidine kinase signalling cascade in islets derived from the Goto-Kakizaki (GK) rat, a model for type 2 diabetes. Potential avenues for future research to further decipher regulatory roles for protein histidine phosphorylation in physiological insulin secretion are also discussed.

Downstream targets of Nm23-H1: gene expression profiling of CAL 27 cells using DNA microarray

The human nm23-H1 was discovered as a tumor metastasis suppressor based on its reduced expression in melanoma cell lines with low versus high metastatic potential. It encodes for one of two subunits of the nucleoside-diphosphate kinase. Besides its role in the maintenance of the cells NTP pool, nm23 plays a key role in different cellular processes. The role of nm23-H1 in these processes still has to be elucidated. Our goal was to identify Nm23-H1 downstream targets by subjecting Nm23-H1 overexpressing CAL 27 cells oral squamous cell carcinoma (OSSC) to microarray analysis. The genes with changed expression patterns could be clustered into several groups: transforming growth factor beta (TGFbeta) signaling pathway, cell adhesion, invasion and motility, proteasome machinery, cell-cycle, epithelial structural and related molecules and others. Based on the expression patterns observed we presume that nm23-H1 might have a role in OSSCs, which should be confirmed by future experiments.

Intracellular Levels of S-Adenosylhomocysteine but Not Homocysteine Are Highly Correlated to the Expression of nm23-H1 and the Level of 5-Methyldeoxycytidine in Human Hepatoma Cells With Different Invasion Activities

Cellular methylation imbalance is associated with tumor progression, hepatic cancer, and cardiovascular disease. S-Adenosylhomocysteine (SAH) is an inhibitor of cellular methyltransferases, and increasing evidence suggests that SAH rather than homocysteine (Hcy) plays a crucial role in mediating these disorders related to methylation imbalance. The anti-metastatic gene nm23-H1 was recently identified in murine and human cancer lines, and the expressions of nm23-H1 mRNA and protein have been shown to be useful tumor invasion markers. We investigated the relationships of tumor cell invasion activities with the intracellular levels of SAH and Hcy and the level of DNA methylation (measured as the cellular content of 5-methyldeoxycytidine, 5-mdc) in four hepatocarcinoma cell lines (Sk-Hep1, J5, Hep-G2, Hep-3B) and one normal liver cell line (Chang's liver cells) with different invasion activities (Sk-Hep1 > J5 > Hep-G2 = Hep-3B > Chang's liver cells). We found that the intracellular level of SAH was the highest in SK-Hep1 cells and was correlated with the invasion activities (r = 0.75, P = 0.008), whereas the level of intracellular Hcy was the highest in Chang's liver cells and was not significantly correlated with the invasion activities of these cell lines (r = 0.24, P = 0.38). The levels of 5-mdc increased with decreasing invasion activities of these cell lines (r = 0.82, P = 0.002), that is, the order of DNA hypomethylation in these cell lines was Sk-Hep1 > J5 > Hep-G2 = Hep-3B > Chang's liver cells, because the lower levels of 5-mdc% represent the higher DNA hypomethylation. Thus, our results demonstrate that SAH rather than Hcy is associated with invasion activities of hepatoma cells, and they suggest that SAH may play an important role in the invasion activities through DNA hypomethylation.

Epstein-Barr virus protein can upregulate cyclo-oxygenase-2 expression through association with the suppressor of metastasis Nm23-H1

Previous studies have demonstrated the interaction between the Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA3C) and the metastatic suppressor Nm23-H1 both in vitro and in vivo (C. Subramanian, M. A. Cotter II, and E. S. Robertson, Nat. Med. 7:350-355, 2001). EBNA3C can reverse the ability of Nm23-H1 to suppress migration of Burkitt's lymphoma and breast carcinoma cell lines in vitro. EBNA3C contributes to EBV-associated human cancers by regulating transcription of a number of cellular and viral promoters and by targeting and altering the transcription activities of the metastasis suppressor Nm23-H1. Cyclo-oxygenase-2 (COX-2), an inducible enzyme important in inflammation, is overexpressed in a variety of cancers and can influence cell migration. In this report we show that Nm23-H1 and EBNA3C can modulate expression of COX-2 in the context of EBV infection and transformation. The levels of COX-2 were consistently higher in EBV-positive cells than in EBV-negative cells. Additionally, we show that Nm23-H1 can upregulate the COX-2 promoter element in luciferase reporter assays, whereas EBNA3C alone did not affect the level of response but clearly contributed to an additive increase when coexpressed with Nm23-H1. The downstream effect of COX-2 expression was also evaluated and showed that prostaglandin E(2) levels increased with Nm23-H1 and that there was some level of cooperativity in the presence of EBNA3C. The majority of this response was mediated through the cyclic AMP response element and NF-kappaB sites. These studies suggest a potential role for COX-2 in EBV-associated human cancers.

Clinical significance of serum NM23-H1 protein in neuroblastoma

We have previously reported that NM23 genes are overexpressed in various hematological malignancies and that serum NM23-H1 protein levels are useful for predicting patient outcomes. In this study we assessed the clinical implications of serum NM23-H1 protein on neuroblastoma. We examined serum NM23-H1 protein levels in 217 patients with neuroblastoma, including 131 found by mass-screening and 86 found clinically by an enzyme-linked immunosorbent assay, and determined the association between levels of this protein, and known prognostic factors or the clinical outcome. The serum NM23-H1 protein level was higher in neuroblastoma patients than in control children (P < 0.0001). Patients with MYCN amplification had higher serum NM23-H1 levels than those with a single copy of MYCN. Overall survival was assessed in the 86 patients found clinically, and was found to be worse in patients with higher serum MN23-H1 levels (> or = 250 ng/mL) than in those with lower levels (< 250 ng/mL; P = 0.034). The higher level of NM23-H1 was correlated with a worse outcome in patients with a single MYCN copy, or in those younger than 12 months of age. Serum NM23-H1 protein levels may contribute to predictions of clinical outcome in patients with neuroblastoma.

Expression of E-cadherin and nm23 is associated with the clinicopathological factors of human non-small cell lung cancer in China

E-cadherin, a calcium-dependent cell-cell adhesion molecule, functions as maintenance of epithelial integrity. nm23, encoded by non-metastatic 23 gene, plays a key role in differentiation of many kinds of epithelium. Loss or dysfunction of E-cadherin and nm23 was frequently identified in many types of human cancers and is considered to correlate with invasive/metastatic phenotype. We previously reported that defective expression of E-cadherin might play a role in the development of the malignant phenotype in non-small cell lung cancer (NSCLC) [Q.Y. Fei, H.T. Zhang, X.F. Chen, et al., Defected expression of Ecadherin in non-small cell lung cancer, Lung Cancer 37 (2002) 147-152]. In an attempt to evaluate the significance of E-cadherin and nm23 in human non-small cell lung cancer, we performed mRNA expression and genetic structure analyses of the E-cadherin and nm23 genes in 54 NSCLCs and 46 normal lung tissues. The mRNA expression was determined by semi-quantitative RT-PCR, and genetic structure was examined through PCR-SSCP followed by sequencing. Although no mutation of the E-cadherin and nm23 genes was detected, the results obtained in the present study showed that reduction of E-cadherin and nm23 mRNA expression remarkably correlated with low histological differentiation, increasing stage as well as lymph node metastases (P<0.05). These data provide us with support for the idea that dysfunction of E-cadherin and nm23 has a role in progression of NSCLC and that the examination of E-cadherin and nm23 expression can provide experimental evidence for clinical treatment.

Epstein-Barr virus nuclear antigen 1 interacts with Nm23-H1 in lymphoblastoid cell lines and inhibits its ability to suppress cell migration

Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is expressed in the majority of latency programs in EBV-infected cells and is critical for the maintenance of EBV episomes in the infected cells. EBNA1 is also known to be involved in transcriptional activation and regulates expression of the EBV latent genes, including the EBNAs and LMP1. Thus, EBNA1 is a multifunctional protein with critical functions required for the persistence of the viral genome over successive generations, producing new daughter cells from the infected cell. We identify EBNA1 here as an interacting EBNA with the known suppressor of metastasis and cell migration, Nm23-H1. Nm23-H1 inhibits cell migration when expressed in cancer cells. We show that EBNA1 associates with Nm23-H1 in EBV-infected cells in vitro, as well as in lymphoblastoid cell lines (LCLs). Nm23-H1 predominantly localizes to the cytoplasm in BJAB and 293T cells; however, upon expression of EBNA1, Nm23-H1 is translocated to the nucleus in similar compartments to EBNA1, suggesting a potential functional role that is linked to EBNA1. Convincingly, in EBV-transformed LCLs Nm23-H1 is localized predominantly to the nucleus and colocalizes to similar compartment as EBNA1. Further, we tested the effects of EBNA1 on Nm23-H1-mediated suppression of cell migration and showed that EBNA1 rescues the suppression of cell migration mediated by Nm23-H1. These in vitro studies suggest that EBNA1 plays a critical role in regulating the activities of Nm23-H1, including cell migration, through a mechanism which involves direct interaction of this major regulator in EBV-infected cells.

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.

Reduced metastasis-suppressor gene mRNA-expression in breast cancer brain metastases

PURPOSE

Brain metastases are an increasingly common complication in breast cancer patients. The Metastasis Suppressor Genes (MSG) Nm23, KISS1, KAI1, BRMS1, and Mkk4 have been associated with the metastatic potential of breast cancer in vitro and in vivo.

METHODS

The mRNA expression of Nm23, KISS1, KAI1, BRMS1, and Mkk4 in fresh frozen tissue samples of brain metastases from ductal invasive breast cancer specimens was examined in relation to primary tumors. In a first step, mRNA expression screening was carried out using a semi-quantitative RT-PCR approach, in a second step quantitative real-time RT-PCR was performed on selected specimens. By immunohistochemical staining, gene products were visualized on the protein level.

RESULTS

Semi-quantitative RT-PCR revealed reduced mRNA expression of Nm23, KISS1, KAI1, BRMS, and Mkk4 in brain metastases. Results for KISS1, KAI1, BRMS, and Mkk4 were confirmed by real-time RT-PCR. In detail, mRNA expression reduction in breast cancer brain metastases was tenfold. Expression of MSG could be confirmed by immunohistochemical staining on protein level.

CONCLUSIONS

Our investigations revealed significantly reduced mRNA expression of metastases suppressor genes KISS1, KAI1, BRMS1, and Mkk4 in breast cancer brain metastasis. Particularly, in the case of KISS1 and Mkk4, an important role for future treatment of patients with breast cancer brain metastatic lesions can be assumed.

Acute lymphoblastic leukemia with TEL-AML1 fusion has lower expression of genes involved in purine metabolism and lower de novo purine synthesis

Because de novo purine synthesis (DNPS) is a target of widely used antileukemic agents (eg, methotrexate, mercaptopurine), we determined the rate of DNPS and the expression of genes involved in purine metabolism in different subtypes of acute lymphoblastic leukemia (ALL). Among 113 children with newly diagnosed ALL, lymphoblasts with the TEL-AML1 translocation had significantly lower DNPS than all other genetic subtypes of B-lineage ALL or T-lineage ALL (352 ± 57 versus 1001 ± 31 or versus 1315 ± 76 fmol/nmol/h, P &lt; .0001). By assessing the expression of 82 genes involved in purine metabolism (KEGG pathway database) in ALL blasts from 38 patients with B-lineage ALL (14 with TEL-AML1, 24 without), we identified 16 genes that were differentially expressed in TEL-AML1–positive and TEL-AML1–negative ALL (P &lt; .001, false discovery rate [FDR] = 5%). The pattern of expression of these 16 genes discriminated TEL-AML1–positive ALL with a true accuracy of 84% in an independent test set (n = 17, confidence interval 70% to 94%, P &lt; .001). Western blots of selected genes documented corresponding levels of the proteins encoded. Differentially expressed genes included HPRT, IMPDH, PAICS, and GART, all of which were expressed at a significantly lower level in TEL-AML1 ALL. These findings have established that TEL-AML1 ALL has significantly lower de novo purine synthesis and differential expression of genes involved in purine metabolism.

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.

Histone acetylation and gastrointestinal carcinogenesis

The importance of altered histone acetylation in gastrointestinal carcinogenesis, especially in relation to invasion and metastasis, is described. Histone acetylation and chromatin remodeling linked with CpG island methylation play a major role in epigenetic regulation of gene expression. Acetylation of histones through an imbalance of histone acetyltransferases and deacetylases disrupts nucleosome structure, which leads to DNA relaxation and subsequent increase in accessibility to transcription factors. The expression of acetylated histone H4 is reduced in a majority of gastric and colorectal cancers, indicating the low level of global histone acetylation in tumor cells. Moreover, reduced histone acetylation is significantly associated with depth of tumor invasion and nodal metastasis of gastrointestinal cancers. A histone deacetylase inhibitor, trichostatin A (TSA), induces growth arrest and apoptosis and suppresses invasion of cancer cells. Treatment with TSA, which is followed by increased histone acetylation in the promoters, induces the expression of many genes that are suppressors of invasion and metastasis, including tissue inhibitors of metalloproteinase and nm23H1/H2, in addition to negative cell cycle regulators and apoptosis-related molecules. Our approach, serial analysis of gene expression (SAGE), enabled us to identify a gene that is a novel candidate for a metastasis suppressor, whose expression is induced by histone acetylation. These findings suggest that, by modifying gene expression, histone deacetylation may participate not only in tumorigenesis but also in invasion and metastasis. Therefore, histone acetylation should be a promising target for cancer therapy, especially against invasive and metastatic disease, but also for cancer prevention.

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.

Clinical significance of nm23-H1 proteins expressed on cell surface in non-Hodgkin's lymphoma

The nm23 gene was isolated as a metastasis suppressor gene that exhibits low expression in high-level metastatic cancer cells. Its gene is related to the prognosis of acute myelogenous leukemia (AML) and non-Hodgkin's lymphoma (NHL). In this study, we examined the expression of nm23-H1 protein on the lymphoma cell surface of NHL. In 28 of 108 cases (25.9%), we observed > or = 20% of cell surface nm23-H1 protein expression and expression was especially high in peripheral T cell lymphomas and extranodal NK/T cell lymphomas. We also observed a significant correlation between serum nm23-H1 level and cell surface nm23-H1 expression levels. In patients with high levels of cell surface nm23-H1 expression, overall and progression-free survival rates were significantly lower than those in patients with low surface nm23-H1 expression levels. When surface nm23-H1 and serum nm23-H1 were combined, patients with high levels of both exhibited a poorer prognosis than patients with a high level of one or the other. These results indicate that in addition to serum nm23-H1, cell surface nm23-H1 may be used as a prognostic factor in planning a treatment strategy. The nm23-H1 protein appears to be intimately related to biological aggressiveness of lymphoma and, therefore, might be a molecular target of NHL treatment.

[Prognosis in patients with potentially treatable colorectal carcinoma]

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The concentration of serum transforming growth factor beta-1 (TGF-beta1) is decreased in cervical carcinoma patients

Transforming growth factor beta-1 (TGF-beta1) is a multifunctional growth factor and known to inhibit the proliferation of epithelial cell. The relationship between serum TGF-beta1 level and the presence of cervical cancer was investigated in this study. The patients with cervical squamous cell carcinoma (SCC) had significantly lower level of serum TGF-beta1 (39.14 +/- 9.03 ng/mL; mean +/- SD) than those with myoma (49.17 +/- 9.38 ng/mL) and normal subjects (49.13 +/- 8.81 ng/mL), (p < 0.007 and p < 0.001, respectively). TGF-beta1 level was also lower in the patients with cervical intraepithelial neoplasia (CIN3) (42.07 +/- 9.38 ng/mL) than in normal controls (49.13 +/- 8.81 ng/mL) (p < 0.04). It suggested that diminution of the production of TGF-beta1 has close association with the neoplastic transformation of cervical epithelium.

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.

Serum nm23-H1 protein as a prognostic factor in aggressive non-Hodgkin lymphoma

Advances in chemotherapy have led to a favorable long-term prognosis in approximately 50% of patients with aggressive non-Hodgkin lymphoma (NHL). However, the remaining patients do not enjoy such prolonged survival after standard treatment. New prognostic factors are needed to define this poor-prognosis group and to plan an appropriate treatment strategy. It has been reported that serum nm23-H1 protein may be a new prognostic factor for aggressive NHL. In the present study involving multiple institutions and a large number of patients, the level of nm23-H1 protein was compared among different types of lymphoma; it was lowest for indolent lymphoma, followed by aggressive lymphoma and then highly aggressive lymphoma. In addition, patients with aggressive NHL and higher nm23-H1 levels had worse overall and progression-free survival rates than those with lower nm23-H1 levels. The nm23-H1 level was also compared between patients with diffuse large B-cell lymphoma and patients with peripheral T-cell lymphoma. The results suggest that the level of nm23-H1 could serve as a prognostic factor in both groups. Moreover, the prognosis of lymphoma patients could be ascertained even more precisely by combining soluble interleukin-2 receptor or soluble CD44 and nm23-H1 levels. A multivariate analysis confirmed that the nm23-H1 level is an independent and important prognostic factor in aggressive NHL. Therefore, it may provide useful information for clinicians to determine the appropriate therapy for each type of lymphoma.

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.

Epstein-Barr virus nuclear protein EBNA-3C interacts with the human metastatic suppressor Nm23-H1: a molecular link to cancer metastasis

Epstein-Barr virus (EBV) is an oncogenic virus associated with a number of human malignancies including Burkitt lymphoma, nasopharyngeal carcinoma, lymphoproliferative disease and, though still debated, breast carcinoma. A subset of latent EBV antigens is required for mediating immortalization of primary B-lymphocytes. Here we demonstrate that the carboxy-terminal region of the essential latent antigen, EBNA-3C, interacts specifically with the human metastatic suppressor protein Nm23-H1. Moreover, EBNA-3C reverses the ability of Nm23-H1 to suppress the migration of Burkitt lymphoma cells and breast carcinoma cells. We propose that EBNA-3C contributes to EBV-associated human cancers by targeting and altering the role of the metastasis suppressor Nm23-H1.

nm23-H1 protein expression in anal canal carcinoma: does it correlate with prognosis?

BACKGROUND AND OBJECTIVES

Anatomic extent is not the sole axis of classification of tumors and of tumor patients relevant to treatment planning and estimation of prognosis. This results in the need to demonstrate an improvement in prognostic assessment and choice of therapy achieved by consideration of factors other than TNM. nm23 protein does prevent tumor from metastasizing and may also play a role in the control of growth and development. The purpose of this study was to elucidate the clinical significance of nm23 expression in human anal canal carcinoma and to evaluate its influence on the outcome of patients after surgery or radiochemotherapy.

METHODS

Twenty-two patients affected by anal canal carcinoma were evaluated. Each section was incubated with monoclonal antibody nm23 NDPK-A. Immunostaining was considered positive when at least 10% of the tumor cells were immunostained.

RESULTS

nm23 immunoreactivity was detected in 6/22 (27.3%) tumors. No significant association was found between nm23 expression and prognosis.

CONCLUSIONS

The mechanisms causing enhanced nm23-H1 expression in anal canal carcinoma are unknown. Although the level and expression were not correlated with prognosis, activation of nm23-H1 gene might be a prerequisite for oncogenesis in this type of tumor, while an alternate possibility is the modification of cellular characteristics in relation to proliferation and/or differentiation as a consequence of oncogenesis.

Colorectal cancer staging and adjuvant chemotherapy

Colorectal cancer is a significant cause of morbidity and mortality in Western populations. The standard of care for staging patients with colorectal cancer to determine prognosis and identify patients who will receive adjuvant therapy continues to be histopathology of regional lymph nodes. However, the significant variability in survival within each staging category likely reflects the heterogeneity of detecting micrometastatic disease employing this technique. Novel molecular markers of micrometastases currently in development will permit more accurate staging of patients with colorectal cancer. These advances in staging will distinguish patients who will maximally benefit from adjuvant therapy from those who have an especially good prognosis in whom chemotherapy can be avoided. In addition, new adjuvant chemotherapeutic agents, novel combinations of those agents and creative dosing schedules currently being investigated will offer considerable advantages with respect to ease of administration, safety and tolerability, quality of life and efficacy. Ultimately, it is anticipated that advances in molecular diagnostics will define unique biochemical characteristics of patients' tumours, permitting individualization of chemotherapeutic regimens employing novel agents that specifically exploit those characteristics.

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.

The significance of metastasis-related factors cathepsin-D and nm23 in advanced ovarian cancer

BACKGROUND

Different regulators or effectors of the metastatic cascade can be of prognostic and/or predictive significance. Cathepsin-D and nm23 operate at different levels of the metastatic process and have not yet been analyzed in combination in ovarian cancer.

PATIENTS AND METHODS

The prevalence of cathepsin-D and nm23 expression was studied with immunohistochemistry in a cohort of 185 previously untreated cases of FIGO stage III ovarian cancer. Correlations with known prognostic factors were examined, and both uni- and multivariate survival analyses were performed.

RESULTS

Epithelial cell cathepsin-D expression was found in 58% of cases, stromal cell cathepsin-D expression in 20%, and nm23 expression in 72%. Epithelial cell cathepsin-D expression was positively correlated with better differentiation of the tumor tissue (P = 0.034). No correlation was found between epithelial and stromal cell cathepsin-D expression, but a striking degree of positive correlation was demonstrated between epithelial cell cathepsin-D and nm23 expression (P = 0.005). None of the factors studied was of any value in predicting the response to platinum and anthracyclin combination chemotherapy, as assessed by second look laparotomy. In univariate analysis age, FIGO substage, histological type, differentiation grade, ascites, residual disease and epithelial cathepsin-D were associated with corrected survival. Neither stromal cell cathepsin-D, nor nm23 expression were of prognostic significance. However, in multivariate analysis the combination of epithelial and stromal cell cathepsin-D expression (P = 0.030), residual disease (P = 0.002) and differentiation grade (P = 0.007) were the only remaining independent prognostic factors in this patient group.

CONCLUSIONS

Our results support a favourable prognostic significance of cathepsin-D expression in advanced ovarian cancer, but underscore the importance of considering both epithelial and stromal cell expression. We could not confirm the prognostic significance of nm23 expression in the present cohort of advanced ovarian cancer patients.

Resistance to apoptosis induced by microenvironmental stresses is correlated with metastatic potential in Lewis lung carcinoma

The apoptosis-resistant phenotype of cloned high-metastatic A11 and low-metastatic P29 cells isolated from Lewis lung carcinoma was compared. The results showed that A11 cells were more resistant to apoptosis induced by microenvironmental stresses such as serum starvation, glucose deprivation and hypoxia than P29 cells as judged by viability, DNA laddering, and chromatin condensation and fragmentation. Both cell lines were insensitive to tumor necrosis factor-alpha-mediated apoptosis. P29 cells expressed a much higher level of Fas antigen on the cell surface than A11 cells. However, both cell lines were also insensitive to Fas-mediated apoptosis. The apoptosis resistant phenotype of A11 cells was associated with the expression level of caspase-3, but not with those of Bcl-2, Bcl-X(L) Bax, p27Kip1 and DAP kinase. There was no difference between A11 and P29 cells in the expression of E-cadherin, the adhesiveness to the extracellular matrix components or the expression levels of metastasis-associated genes such as c-Ha-ras, c-jun, p53 and nm23. Furthermore, A11 cells exhibited lower motile and invasive abilities than P29 cells. These results suggest that the apoptosis-resistant phenotype is an important factor for determining the metastatic ability of A11 cells. Supporting this, P29 cells became more apoptosis-resistant after treatment of the cells with dimethylsulfoxide which is reported to enhance the experimental metastatic potential of the cells.

Nm23-transfected MDA-MB-435 human breast carcinoma cells form tumors with altered phospholipid metabolism and pH: a 31P nuclear magnetic resonance study in vivo and in vitro

Nm23 genes are involved in the control of the metastatic potential of breast carcinoma cells. To understand the impact of nm23 genes on tumor physiology and metabolism, a 31P nuclear magnetic resonance (NMR) spectroscopic study was performed on tumors formed in the mammary fat pad of severe combined immunodeficiency mice by MDA-MB-435 human breast carcinoma cells transfected with cDNA encoding wild type nm23-H1 and nm23-H2 proteins. Tumors formed by MDA-MB-435 cells transfected with vector alone were used as controls. All transgene tumors exhibited significantly higher levels of phosphodiester (PDE) compounds relative to phosphomonoester (PME) compounds in vivo compared with control tumors. Similar differences in PDE and PME also were observed for spectra obtained from cells growing in culture. Intracellular pH was significantly lower and extracellular pH was significantly higher for transgene tumors compared with control tumors. Histologic analysis of lung sections confirmed reductions in incidence, number, and size of metastatic nodules for animals bearing transgene tumors. These results suggest that nm23 genes may affect suppression of metastasis through phospholipid-mediated signaling and cellular pH regulation.