Rab17 inhibits the tumourigenic properties of hepatocellular carcinomas via the Erk pathway

The small GTPase Rab17 is a member of the Rab family and plays a critical role in the regulation of membrane trafficking polarized eukaryotic cells. However, the role of Rab17 in hepatocellular carcinoma (HCC) is not clear. In the present study, we investigated the role of Rab17 in HCC tumourgenesis. The expressions of Rab17 in non-tumour hepatic tissues and HCCs were detected via immunohistochemistry. Rab17 was found in 31 of 48 (64.6 %) and in 23 of 62 (37.1 %) of non-tumour hepatic tissue samples and HCCs (P = 0.0068), respectively, and there were significant correlations between Rab17 reductions and unfavourable variables including tumour size (P = 0.0171), differentiation level (P = 0.0126), and lymph nodal (P = 0.0044) and distant metastases (P = 0.0047). To elucidate the role of Rab17 in HCC, we generated two Rab17-overexpressing HCC cell lines. Rab17 overexpression significantly inhibited the tumourigenic properties of HCC cells in vitro and in vivo as demonstrated by reduced cell proliferation and migration, elevated G1 arrest, and decreased tumour xenograft growth. However, the attenuated tumourigenic properties of the HCC cells that were induced by Rab17 overexpression were significantly rescued by the activator of the Erk pathway EGF, which indicates that the Erk pathway plays a critical role in the Rab17 up-regulation-induced reduced tumourigenic properties of HCC cells. Rab17 might act as a tumour suppressor gene in HCCs, and the anti-tumour effects of Rab17 might be partially mediated by the Erk pathway.

Exercise modulates redox-sensitive small GTPase activity in the brain microvasculature in a model of brain metastasis formation

Tumor cell extravasation into the brain requires passage through the blood-brain barrier (BBB). There is evidence that exercise can alter the oxidation status of the brain microvasculature and protect against tumor cell invasion into the brain, although the mechanisms are not well understood. In the current study, we focused on the role of microenvironment generated by exercise and metastasizing tumor cells at the levels of brain microvessels, influencing oxidative stress-mediated responses and activation of redox-sensitive small GTPases. Mature male mice were exercised for four weeks using a running wheel with the average voluntary running distance 9.0 ± 0.3 km/day. Mice were then infused with 1.0 × 10(6) D122 (murine Lewis lung carcinoma) cells into the brain microvasculature, and euthanized either 48 hours (in short-term studies) or 2-3 weeks (in long-term studies) post tumor cell administration. A significant increase in the level of reactive oxygen species was observed following 48 hours or 3 weeks of tumor cells growth, which was accompanied by a reduction in MnSOD expression in the exercised mice. Activation of the small GTPase Rho was negatively correlated with running distance in the tumor cell infused mice. Together, these data suggest that exercise may play a significant role during aggressive metastatic invasion, especially at higher intensities in pre-trained individuals.

Use of the foot-and-mouth disease virus 2A peptide co-expression system to study intracellular protein trafficking in Arabidopsis

Background

A tool for stoichiometric co-expression of effector and target proteins to study intracellular protein trafficking processes has been provided by the so called 2A peptide technology. In this system, the 16–20 amino acid 2A peptide from RNA viruses allows synthesis of multiple gene products from single transcripts. However, so far the use of the 2A technology in plant systems has been limited.

Methodology/Principal Findings

The aim of this work was to assess the suitability of the 2A peptide technology to study the effects exerted by dominant mutant forms of three small GTPase proteins, RABD2a, SAR1, and ARF1 on intracellular protein trafficking in plant cells. Special emphasis was given to CAH1 protein from Arabidopsis, which is trafficking to the chloroplast via a poorly characterized endoplasmic reticulum-to-Golgi pathway. Dominant negative mutants for these GTPases were co-expressed with fluorescent marker proteins as polyproteins separated by a 20 residue self-cleaving 2A peptide. Cleavage efficiency analysis of the generated polyproteins showed that functionality of the 2A peptide was influenced by several factors. This enabled us to design constructs with greatly increased cleavage efficiency compared to previous studies. The dominant negative GTPase variants resulting from cleavage of these 2A peptide constructs were found to be stable and active, and were successfully used to study the inhibitory effect on trafficking of the N-glycosylated CAH1 protein through the endomembrane system.

Conclusions/Significance

We demonstrate that the 2A peptide is a suitable tool when studying plant intracellular protein trafficking and that transient protoplast and in planta expression of mutant forms of SAR1 and RABD2a disrupts CAH1 trafficking. Similarly, expression of dominant ARF1 mutants also caused inhibition of CAH1 trafficking to a different extent. These results indicate that early trafficking of the plastid glycoprotein CAH1 depends on canonical vesicular transport mechanisms operating between the endoplasmic reticulum and Golgi apparatus.

[Construction of recombinant lentiviral vectors containing Rheb gene and its mutant Rheb'D60K gene and their expression in human liver cancer cells]

OBJECTIVE

To construct recombinant lentiviral vectors carrying Rheb gene and its mutant Rheb'D60K gene, and examine their expression in human liver cancer cells.

METHODS

Rheb gene was amplified by PCR to construct the recombinant plasmid LV31-Rheb-WT and LV31-Rheb-D60K. HEK-293 FT cells were contransfected with the recombinant lentiviral vector together with a lentiviral package plasmid to produce the lentiviral particles. The expression of PS6 protein was detected in the lentivirus-infected MCF-7 cells. The apoptosis of SK-HEP-1 cells transfected with LV31-Rheb-WT or LV31-Rheb-D60K was observed.

RESULTS

The recombinant LV31-Rheb-WT and LV31-Rheb-D60K vectors were confirmed by PCR and DNA sequencing. Western blotting showed that PS6 protein expression was increased in LV31-Rheb-WT-transfected cells while decreased in LV31-Rheb-D60K-transfected cells. LV31-Rheb-D60K-transfected SK-HEP-1 cells showed more obvious apoptosis after starvation than LV31-Rheb-WT-transfected cells.

CONCLUSION

Lentiviral vectors carrying Rheb gene and its mutant has been successfully constructed, which can be useful in further investigation of the role of Rheb gene in cancer cells.

Suppression of hydroxyurea-induced centrosome amplification by NORE1A and down-regulation of NORE1A mRNA expression in non-small cell lung carcinoma

The candidate tumor suppressor NORE1A is a nucleocytoplasmic shuttling protein, and although a fraction of the NORE1A in cells is localized to their centrosomes, the role of centrosomal NORE1A has not been elucidated. In this study we investigated the role of NORE1A in the numerical integrity of centrosomes and chromosome stability in lung cancer cells. Exposure of p53-deficient H1299 lung cancer cell line to hydroxyurea (HU) resulted in abnormal centrosome amplification (to 3 or more centrosomes per cell) as determined by immunofluorescence analysis with anti-γ-tubulin antibody, and forced expression of wild-type NORE1A partially suppressed the centrosome amplification. The nuclear export signal (NES) mutant (L377A/L384A) of NORE1A did not localize to centrosomes and did not suppress the centrosome amplification induced by HU. Fluorescence in situ hybridization analyses with probes specific for chromosomes 2 and 16 showed that wild-type NORE1A, but not NES-mutant NORE1A, suppressed chromosome instability in HU-exposed H1299 cells that was likely to have resulted from centrosome amplification. We next examined the status of NORE1A mRNA expression in non-small cell lung carcinoma (NSCLC) and detected down-regulation of NORE1A mRNA expression in 25 (49%) of 51 primary NSCLCs by quantitative real-time-polymerase chain reaction analysis. These results suggest that NORE1A has activity that suppresses the centrosome amplification induced by HU and that NORE1A mRNA down-regulation is one of the common gene abnormalities in NSCLCs, both of which imply a key preventive role of NORE1A against the carcinogenesis of NSCLC.

Rheb activates protein synthesis and growth in adult rat ventricular cardiomyocytes

The mammalian target of rapamycin complex 1 (mTORC1), a key regulator of protein synthesis, growth and proliferation in mammalian cells, is implicated in the development of cardiac hypertrophy. Ras homolog enriched in brain (Rheb) positively regulates mTORC1. We have studied whether Rheb is sufficient to activate mTOR signaling and promote protein synthesis and cardiac hypertrophy in adult rat ventricular cardiomyocytes (ARVC). Rheb was overexpressed via an adenoviral vector in isolated ARVC. Overexpression of Rheb in ARVC activated mTORC1 signaling, several components of the translational machinery and stimulated protein synthesis. Our direct visualization approach to determine ARVC size revealed that overexpression of Rheb also induced cell growth and indeed did so to similar extent to the hypertrophic agent, phenylephrine (PE). Despite potent activation of mTORC1 signaling, overexpression of Rheb did not induce expression of the cardiac hypertrophic marker mRNAs for brain natriuretic peptide and atrial natriuretic factor, while PE treatment did markedly increase their expression. All the effects of Rheb were blocked by rapamycin, confirming their dependence on mTORC1 signaling. Our findings reveal that Rheb itself can activate both protein synthesis and cell growth in ARVC and demonstrate the key role played by mTORC1 in the growth of cardiomyocytes.

Cloning, genomic organization, and tissue-specific expression of the RASL11B gene

RASL11B is a member of the small GTPase protein family with a high degree of similarity to RAS proteins. Cloning of RASL11B mRNA and in silico analyses revealed that the human RASL11B gene spans about 4.5 kb and comprises four exons on chromosomal locus 4q12. The proximal 5'-flanking region of the gene lacks a TATA box but is GC-rich and contains a CCAAT box and several Sp1 sites. Consistent with this, the RASL11B gene was found to be expressed in all tissues investigated, with highest levels in placenta and in primary macrophages. The predicted RASL11B protein has no typical prenylation signal, indicating that it is probably not anchored to cellular membranes. RASL11B was induced during maturation of THP-1 monocytic cells into macrophage-like cells and in coronary artery smooth muscle cells after treatment with TGF-beta1. These results indicate that RASL11B may play a role in TGF-beta1-mediated developmental processes and in pathophysiologies such as inflammation, cancer, and arteriosclerosis.

RASSF6 is a novel member of the RASSF family of tumor suppressors

RASSF family proteins are tumor suppressors that are frequently downregulated during the development of human cancer. The best-characterized member of the family is RASSF1A, which is downregulated by promoter methylation in 40-90% of primary human tumors. We now identify and characterize a novel member of the RASSF family, RASSF6. Like the other family members, RASSF6 possesses a Ras Association domain and binds activated Ras. Exogenous expression of RASSF6 promoted apoptosis, synergized with activated K-Ras to induce cell death and inhibited the survival of specific tumor cell lines. Suppression of RASSF6 enhanced the tumorigenic phenotype of a human lung tumor cell line. Furthermore, RASSF6 is often downregulated in primary human tumors. RASSF6 shares some similar overall properties as other RASSF proteins. However, there are significant differences in biological activity between RASSF6 and other family members including a discrete tissue expression profile, cell killing specificity and impact on signaling pathways. Moreover, RASSF6 may play a role in dictating the degree of inflammatory response to the respiratory syncytial virus. Thus, RASSF6 is a novel RASSF family member that demonstrates the properties of a Ras effector and tumor suppressor but exhibits biological properties that are unique and distinct from those of other family members.

Dexamethasone represses signaling through the mammalian target of rapamycin in muscle cells by enhancing expression of REDD1

The mammalian target of rapamycin (mTOR), a critical modulator of cell growth, acts to integrate signals from hormones, nutrients, and growth-promoting stimuli to downstream effector mechanisms involved in the regulation of protein synthesis. Dexamethasone, a synthetic glucocorticoid that represses protein synthesis, acts to inhibit mTOR signaling as assessed by reduced phosphorylation of the downstream targets S6K1 and 4E-BP1. Dexamethasone has also been shown in one study to up-regulate the expression of REDD1 (also referred to RTP801, a novel stress-induced gene linked to repression of mTOR signaling) in lymphoid, but not nonlymphoid, cells. In contrast to the findings of that study, here we demonstrate that REDD1, but not REDD2, mRNA expression is dramatically induced following acute dexamethasone treatment both in rat skeletal muscle in vivo and in L6 myoblasts in culture. In L6 myoblasts, the effect of the drug on mTOR signaling is efficiently blunted in the presence of REDD1 RNA interference oligonucleotides. Moreover, the dexamethasone-induced assembly of the mTOR regulatory complex Tuberin. Hamartin is disrupted in L6 myoblasts following small interfering RNA-mediated repression of REDD1 expression. Finally, overexpression of Rheb, a downstream target of Tuberin function and a positive upstream effector of mTOR, reverses the effect of dexamethasone on phosphorylation of mTOR substrates. Overall, the data support the conclusion that REDD1 functions upstream of Tuberin and Rheb to down-regulate mTOR signaling in response to dexamethasone.

Expression of Rem2, an RGK family small GTPase, reduces N-type calcium current without affecting channel surface density

Rad, Gem/Kir, Rem, and Rem2 are members of the Ras-related RGK (Rad, Gem, and Kir) family of small GTP-binding proteins. Heterologous expression of RGK proteins interferes with de novo calcium channel assembly/trafficking and dramatically decreases the amplitude of currents arising from preexisting high-voltage-activated calcium channels. These effects probably result from the direct interaction of RGK proteins with calcium channel beta subunits. Among the RGK family, Rem2 is the only member abundantly expressed in neuronal tissues. Here, we examined the ability of Rem2 to modulate endogenous voltage-activated calcium channels in rat sympathetic and dorsal root ganglion neurons. Heterologous expression of Rem2 nearly abolished calcium currents arising from preexisting high-voltage-activated calcium channels without affecting low-voltage-activated calcium channels. Rem2 inhibition of N-type calcium channels required both the Ras homology (core) domain and the polybasic C terminus. Mutation of a putative GTP/Mg2+ binding motif in Rem2 did not affect suppression of calcium currents. Loading neurons with GDP-beta-S via the patch pipette did not reverse Rem2-mediated calcium channel inhibition. Finally, [(125)I]Tyr22-omega-conotoxin GVIA cell surface binding in tsA201 cells stably expressing N-type calcium channels was not altered by Rem2 expression at a time when calcium current was totally abolished. Together, our results support a model in which Rem2 localizes to the plasma membrane via a C-terminal polybasic motif and interacts with calcium channel beta subunits in the preassembled N-type channel, thereby forming a nonconducting species.

Expression of activated M-Ras in hemopoietic stem cells initiates leukemogenic transformation, immortalization and preferential generation of mast cells

Cultures of purified hemopoietic stem cells transduced with an activated mutant of M-Ras contained abnormal cells that, despite the presence of only low levels of growth factors, generated large, dense colonies of macrophages and blast cells. Cells from these colonies survived and grew continuously in the absence of growth factors and generated clonal cell-lines that were mainly composed of well-differentiated mast cells, with a low frequency of undifferentiated cells. When transplanted into sublethally irradiated syngeneic mice, four out of four such clones gave rise to a systemic mastocytosis and mast-cell leukemia. However, the donor clones also generated low percentages of cells with the morphological and cell-surface characteristics of erythrocytes, granulocytes, monocytes and T- and B-lymphocytes. These data indicate that signals downstream of activated M-Ras are sufficient to transform hemopoietic stem cells, and while preserving their capacity to generate other cell-lineages in vivo, result in preferential generation of mast cells.

14-3-3 and calmodulin control subcellular distribution of Kir/Gem and its regulation of cell shape and calcium channel activity

Individual members of the RGK family of Ras-related GTPases, which comprise Rad, Gem/Kir, Rem and Rem2, have been implicated in important functions such as the regulation of voltage-gated calcium channel activity and remodeling of cell shape. The GTPase Kir/Gem inhibits the activity of calcium channels by interacting with the beta-subunit and also regulates cytoskeleton dynamics by inhibiting the Rho-Rho kinase pathway. In addition, Kir/Gem interacts with 14-3-3 and calmodulin, but the significance of this interaction on Kir/Gem function is poorly understood. Here, we present a comprehensive analysis of the binding of 14-3-3 and calmodulin to Kir/Gem. We show that 14-3-3, in conjunction with calmodulin, regulates the subcellular distribution of Kir/Gem between the cytoplasm and the nucleus. In addition, 14-3-3 and calmodulin binding modulate Kir/Gem-mediated cell shape remodeling and downregulation of calcium channel activity. Competition experiments show that binding of 14-3-3, calmodulin and calcium channel beta-subunits to Kir/Gem is mutually exclusive, providing a rationale for the observed regulatory effects of 14-3-3 and calmodulin on Kir/Gem localization and function.

Expression patterns of nm23 genes during mouse organogenesis

Nucleoside di-phosphate kinase enzyme (NDPK) isoforms, encoded by the nm23 family of genes, may be involved in various cellular differentiation and proliferation processes. We have therefore analyzed the expression of nm23-M1, -M2, -M3, and -M4 during embryonic mouse development. In situ hybridization data has revealed the differential expression of nm23 mRNA during organogenesis. Whereas nm23-M1 and -M3 are preferentially expressed in the nervous and sensory systems, nm23-M2 mRNA is found ubiquitously. Irrespective of the developmental state studied, nm23-M4 mRNA is only expressed at low levels in a few embryonic organs. In the cerebellum and cerebral cortex, nm23-M1, -M2, and -M3 are present in the neuronal differentiation layer, whereas nm23-M4 mRNA is distributed in the proliferating layer. Thus, nm23 mRNA is differentially expressed, and the diverse NDPK isoforms are sequentially involved in various developmental processes.

Differential membrane localization of ERas and Rheb, two Ras-related proteins involved in the phosphatidylinositol 3-kinase/mTOR pathway

Two Ras-related proteins, ERas and Rheb, which are involved in the phosphatidylinositol 3-kinase pathway, display high GTP affinity and have atypical CAAX motifs. The factors governing the intracellular localization of ERas and Rheb are incompletely understood. In the current study, we show by confocal microscopy that ERas is localized to the plasma membrane, whereas Rheb is confined to the endomembranes. Membrane localization of the two proteins was abolished by mutation of the cysteine of the CAAX motif. Membrane targeting was also abolished by a farnesyltransferase inhibitor but not by a geranylgeranyltransferase inhibitor. In mouse fibroblasts deficient in either Rce1 (Ras converting enzyme 1) or Icmt (isoprenylcysteine carboxyl methyltransferase), ERas was mislocalized mainly to the Golgi apparatus, whereas Rheb showed diffuse localization. Mutation of cysteines in the hypervariable region of ERas prevented the plasma membrane localization of ERas, very strongly suggesting that palmitoylation of the cysteines is essential for membrane targeting. The hypervariable region of Rheb does not contain cysteines or polybasic residues, and when it was replaced with the hypervariable region of H-Ras, Rheb displayed plasma membrane localization. These data indicate that ERas shares the same posttranslational modifications with H-Ras and N-Ras and is localized at the plasma membrane. Rheb also shares the same membrane-targeting pathway but because of the absence of palmitoylation is located on endomembranes.

Identification of differentially expressed genes in oral squamous cell carcinoma

Rapid advances in multimodality therapy have not significantly improved the overall 5-yr survival of oral cancer patients in the past two decades, thereby underscoring the need for molecular therapeutics. The development of new treatment strategies for more effective management of oral cancer requires identification of novel biological targets. Therefore, the aim of this study was to identify novel genes associated with oral tumorigenesis by comparing gene expression profile of oral squamous cell carcinomas (OSCCs) and matched nonmalignant oral epithelial tissues with differential display. Of the 180 differentially expressed cDNAs isolated, reamplified, and cloned into pGEMT-Easy Vector, 26 cDNAs were confirmed to be upregulated in OSCCs by reverse Northern blot analysis. The differentially expressed genes included components of immune system, signaling pathways, angiogenesis, cell structure, proliferation, apoptosis, cell-adhesion, and cellular metabolism. Reverse transcription (RT)-polymerase chain reaction (PCR) analysis of 15 OSCCs and matched nonmalignant oral tissues provided the first evidence that 14-3-3-zeta, melanoma metastasizing clone D (MEMD), KIAA0471, sperm protein 17 (SP17), TC21, and anti-TNF alpha antibody are upregulated in OSCCs. Immunohistochemical analysis confirmed overexpression of 14-3-3-zeta and TC21 protein, a member of the Ras family, in OSCCs as compared to histologically normal oral tissues validating the differential display analysis. Identification of six novel differentially expressed genes in oral tumors adds to the repertoire of genes associated with oral carcinogenesis and provides candidate potential biological targets for diagnosis and/or therapy. Further characterization of the 14 unknown differentially expressed cDNAs identified in this study may provide significant clues for understanding the molecular mechanisms underlying oral tumorigenesis.

Novel roles of unphosphorylated STAT3 in oncogenesis and transcriptional regulation

Signal transducer and activator of transcription 3 (STAT3) is phosphorylated on tyrosine residue 705 in response to growth factors or cytokines to form activated homodimers that drive gene expression. Because the stat3 promoter has a binding site for STAT3 dimers, the amount of STAT3 protein increases when STAT3 is activated (e.g., in response to interleukin 6). Unphosphorylated STAT1 is known to drive the expression of certain genes. To explore the possibility of a similar role for the induced expression of unphosphorylated STAT3, we overexpressed either Y705F STAT3, which can not be phosphorylated on residue 705, or wild-type STAT3 in normal human mammary epithelial cells or STAT3-null mouse cells. The levels of many mRNAs were affected strongly by high levels of either form of STAT3. Some genes whose expression was increased by overexpressed STAT3, but not by activated STAT3 dimers, encode well-known oncoproteins (e.g., MRAS and MET). In many tumors, STAT3 is activated constitutively, and thus the unphosphorylated form is likely to be expressed highly, driving oncogene expression by a novel mechanism. In addition, expression of the stat3 gene is increased strongly in response to interleukin 6, and the high levels of unphosphorylated STAT3 that result drive a substantial late phase of gene expression in response to this cytokine. Thus, unphosphorylated STAT3, which activates gene expression by a novel mechanism distinct from that used by STAT3 dimers, is very likely to be an important transcription factor both in cancer and in responses to cytokines.

RASL11A, member of a novel small monomeric GTPase gene family, is down-regulated in prostate tumors

We performed a genome-wide search for novel loci encoding for Ras-related proteins based on the genome mapping coordinates of the cancer-derived EST dataset at GenBank. Partial sequences from two novel human genes were identified and subsequently used for full length transcript cloning. RASL11A and ARL9 belong to two novel subfamilies coding for small GTPases that we found to be highly conserved among eukaryotes. The Arl9/Arl10 subfamily displays a conserved interswitch toggle that places it evolutionarily closer to the Arf family. Rasl11 proteins are more closely related to the Ras branch of GTPases. All orthologues newly identified here exhibit an Asn residue in place of the highly conserved Thr35 of the G domain, suggesting that the universal switch mechanism of small GTPases may be structurally different in this subfamily. We determined by Northern blot that RASL11A is transcribed in several human tissues and that it is down-regulated in prostate tumors as measured by quantitative real-time PCR. These results highlight a previously uncharacterized subfamily of Ras-related genes that may have a tumor suppressor role in prostate cancer.

Bacteria co-transformed with recombinant proteins and chaperones cloned in independent plasmids are suitable for expression tuning

The efficient over-expression of several recombinant proteins in the same bacterial cell is usually prevented due to metabolic limitations. Nevertheless, the possibility to co-produce high amounts of the sub-units of a complex or to express a wide set of chaperones and foldases could be technologically very useful. We developed a system based on three vectors. Two are under IPTG regulation and enable the recombinant expression of six chaperones, the third one is arabinose-inducible and harbours the sequence for the target protein. In such a way the independent induction and the level of expression of both chaperones and target protein is possible. The data show that the expression leakage from pET vectors was prevented by the introduction of further plasmids in the cell and that the recombinant proteins compete for their expression. In fact, the high rate induction of one of them could switch off the accumulation of the other recombinant proteins. The first information was used to maximise the expression of toxic proteins while the cross-inhibition among recombinant proteins was exploited to modulate and optimise the target protein expression and to induce the chaperone-assisted in vivo re-folding of aggregated target protein.

IL-10-Conditioned Dendritic Cells, Decommissioned for Recruitment of Adaptive Immunity, Elicit Innate Inflammatory Gene Products in Response to Danger Signals

Dendritic cells (DCs) are the professional APCs of the immune system, enabling T cells to perceive and respond appropriately to potentially dangerous microbes, while also being able to maintain T cell tolerance toward self. In part, such tolerance can be determined by IL-10 released from certain types of regulatory T cells. IL-10 has previously been shown to render DCs unable to activate T cells and it has been assumed that this process represents a general block in maturation. Using serial analysis of gene expression, we show that IL-10 pretreatment of murine bone marrow-derived DCs alone causes significant changes in gene expression. Furthermore, these cells retain the ability to respond to Toll-like receptor agonists, but in a manner skewed toward the selective induction of mediators known to enhance local inflammation and innate immunity, among which we highlight a novel CXCR2 ligand, DC inflammatory protein-1. These data suggest that, while the presence of a protolerogenic and purportedly anti-inflammatory agent such as IL-10 precludes DCs from acquiring their potential as initiators of adaptive immunity, their ability to act as initiators of innate immunity in response to Toll-like receptor signaling is enhanced.

Release and interconversion of P2 receptor agonists by human osteoblast-like cells

Nucleotides, acting as agonists at P2 receptors, are important extracellular signaling molecules in many tissues. In bone they affect both bone-forming osteoblast and bone-resorbing osteoclast cell activity. The presence of nucleotides in the extracellular microenvironment is largely determined by their release from cells and metabolism by ecto-enzymes, both of which have scarcely been studied in bone. We have investigated adenosine 5'-triphosphate (ATP) release from SaOS-2 osteoblastic cells and the activities of cell surface ecto-enzymes on ATP metabolism. ATP, but not LDH, was detected in SaOS-2 cell conditioned medium, suggesting these cells were actively releasing ATP. Introduction of ADP resulted in increased ATP concentrations in the medium, which was found not to be receptor mediated. Nucleotide inhibition and substrate specificity studies revealed an ecto-nucleoside diphosphokinase (ecto-NDPK) was responsible for the ADP-->ATP conversion; PCR and immunocytochemistry confirmed its presence. Analysis of ATP metabolism over time demonstrated overall ATP degradation was increased by inhibiting ecto-NDPK activity; confirming that the combined action of multiple osteoblast-expressed ecto-enzymes affected extracellular nucleotide concentration. The data establish the coexistence of ATP-consuming, and for the first time, ATP-generating activities on the osteoblast cell surface, the discovery of which has significant implications for studies involving P2 receptor subtypes in bone.

Clinical significance of high nm23-H1 expression in intraepithelial neoplasia and early-stage squamous cell carcinoma of the uterine cervix

Seventy-two cervical pathology specimens, consisting of samples of cancer and high- and low-grade intraepithelial neoplasia, were used in a study exploring the involvement of nm23-H1/NDP kinase in carcinogenesis or recurrence. Additionally, the relationships between immunohistochemical expression of nm23-H1 and various clinicopathological variables for early-stage cervical cancer were evaluated. The nm23-H1 expression for high-grade cervical intraepithelial neoplasia and squamous cell carcinoma samples was significantly elevated when compared to low-grade analogs. Only deep stromal invasion was significantly associated with high nm23 expression. Moreover, a high cumulative recurrence hazard was demonstrated for the high nm23 expression group. In conclusion, high nm23-H1 expression may induce cellular proliferation for the progression from low- to high- grade intraepithelial neoplasia, with the subsequent emergence of invasive carcinoma as well as deep stromal invasion, and can be used as an indicator of prognosis.

Role of the cgtA gene function in DNA replication of extrachromosomal elements in Escherichia coli

The cgtA gene codes for a common GTP-binding protein whose homologues were found in all prokaryotic and eukaryotic organisms investigated so far. Although cgtA is an essential gene in most bacterial species, its precise functions in the regulation of cellular processes are largely unknown. In Escherichia coli, dysfunction or overexpression of the cgtA gene causes problems in various chromosomal functions, like synchronization of DNA replication initiation and partitioning of daughter chromosomes after a replication round. It is not know how the cgtA gene product regulates these processes. Here we investigated effects of cgtA dysfunction on replication of plasmid and phage replicons. We found that replication of some plasmids (e.g., ColE1-like) is not affected in the cgtA mutant. On the other hand, dysfunction of the cgtA gene caused a strong inhibition of lambda plasmid DNA replication. Bacteriophage lambda development was severely impaired in the cgtA mutant. Replication of other plasmid replicons (derivatives of F, R1, R6K, and RK2) was influenced by the cgtA mutation moderately. It seems that DNA synthesis per se is not affected by CgtA, and that this protein might control replication initiation indirectly, by regulation of function(s) or production of one or more replication factors. In fact, we found that level of the host-encoded replication protein DnaA is significantly decreased in the cgtA mutant. This indicates that CgtA is involved in the regulation of dnaA gene expression.

Expression of nm23 protein in adult soft tissue sarcoma is correlated with histological grade

BACKGROUND

There is controversy about whether expression of nm23 is involved in suppression of metastases or contributes to tumour progression. Few studies have examined the role of nm23 in sarcomas. The aim of this study was to determine if expression of nm23 protein or its H1-subtype correlated with clinicopathological parameters in adult soft tissue sarcomas (STS).

MATERIALS AND METHODS

Protein expression was examined by immunohistochemistry on paraffin-embedded sections of 46 STS patients, quantified using a colour video imaging system and correlated to histological grade. The monoclonal antibodies used were anti-nm23 (recognising both nm23-H1 and nm23-H2) and anti-nm23-H1 (recognising nm23-H1 only).

RESULTS

High-grade tumours significantly overexpressed nm23 (including both nm23-H1 and nm23-H2) compared with both intermediate and low-grade tumours (ANOVA and Tukey, all p < 0.05). Multiple regression analysis confirmed the significance of the relationship and independence of the nm23 (p = 0.005), but not nm23-H1.

CONCLUSION

Expression of nm23 protein, particularly nm23-H2, is an independent predictor of malignant potential of adult STS.

The association of the expression of MTA1, nm23H1 with the invasion, metastasis of ovarian carcinoma

OBJECTIVE

To understanding the molecular mechanisms in invasion and metastasis of the ovarian carcinoma, we investigate a novel candidate metastasis-associated gene (MTA1) and nm23H1 mRNA expression and mutation in ovarian carcinoma.

METHODS

Twenty primary ovarian carcinoma specimens, 20 corresponding lymph nodes and 8 normal ovarian was examined for mRNA expression and mutation of MTA1 and nm23H1 genes by reverse-transcription polymerase chain reaction (RT-PCR) and RT-PCR-SSCP analysis. The level of the expression was determined by the relative optic density (ROD) of the PCR products.

RESULTS

The frequency of MAT1 overexpression was 100% (7/7) in primary ovarian carcinoma with metastasis but only 38.5% (5/13) in those without metastasis (P=0.0103). Overexpression of MAT1 was observed in 87.5% (6/7) of lymph nodes with metastasis but only 23% (3/13) of lymph nodes without metastasis (P=0.0118). In contrast with MAT1, low expression of nm23H1 mRNA was seen in 7 of 7 ovarian carcinoma with metastasis but only in 4 of 13 (30%) of those without metastasis (P=0.0043). Low nm23H1 expression was also seen in 7 of 7 lymph nodes with metastasis but only in 5 of 13 (38.5%) nonmetastatic lymph nodes (P=0.0102). The ROD ratio of MAT1 to nm23H1 increased with the development of metastasis. No mutation of MAT1 and nm23H1 genes was found by SSCP analysis.

CONCLUSION

The mRNA expression of MTA1 and nm23H1 is positively and negatively correlated with lymph node metastasis, respectively. Expression abnormalities but not mutation of the two genes are frequent events related to lymph node metastasis of ovarian cancer.

Nm23-H1 immunohistochemical expression in multisteps of cervical carcinogenesis

To evaluate the expression of nm23-H1 protein in normal, precancerous, and cancerous tissues of the uterine cervix and its role in cervical carcinogenesis, metastasis and recurrence, 82 cervical specimens, including 30 squamous cell carcinomas (SCC), 19 high- and 13 low-grade squamous intraepithelial lesions (HSILs and LSILs) and 20 normal samples, were stained using immunohistochemical method with streptavidin-biotin peroxidase immunostaining. The Chi-square and Fisher's exact tests, as well as Chi-square test for trend, were used for comparing nm23-H1 expression among normal, LSIL, HSIL, and cancerous tissues. The correlation of nm23 expression with metastasis or recurrence was analyzed using Fisher's exact test. There were significant differences in levels of nm23-H1 expression between LSIL and HSIL (P = 0.016) and between LSIL and SCC (P = 0.004), but not between HSIL and SCC or normal and LSIL samples. Furthermore, a positive relationship was demonstrated for high nm23-H1 protein expression and degree of malignant transformation (P < 0.05). Among the 30 SCC cases, high nm23-H1 expression did not show significant association with either carcinomatous metastasis or recurrence (P = 0.123, 0.372, respectively). High nm23-H1 expression appears related to critical progression of LSIL to HSIL but not to metastasis or recurrence of SCC.

PCD1, a novel gene containing PDZ and LIM domains, is overexpressed in human breast cancer and linked to lymph node metastasis

BACKGROUND

Despite surgical removal of the primary tumor of breast cancer in patients with apparently localized disease, relapse at local or distant sites may occur because undetectable micrometastases were present at the time of diagnosis. Identification of molecules associated with breast cancer metastasis suggests possible new treatments. PCD1, a gene encoding a new member of the PDZ and LIM domain-containing protein family, recently was identified. We examined the relationships between PCD1 mRNA expression in breast cancers and metastasis.

MATERIALS AND METHODS

PCD1 mRNA expression in breast cancer tissues was examined using a quantitative reverse transcription polymerase chain reaction.

RESULTS

PCD1 mRNA expression was greater in cancers than in noncancerous tissues (p < 0.0001). In addition, high PCD1 gene expression was more frequent in patients with lymph node metastasis.

CONCLUSION

PCD1 appears to contribute to breast cancer progression and nodal metastasis, thus representing a potential target molecule in breast cancer diagnosis and treatment.

Selective serotonin reuptake inhibitors directly signal for apoptosis in biopsy-like Burkitt lymphoma cells

Selective serotonin reuptake inhibitors (SSRIs) are the treatment of choice for clinical depression and a range of anxiety-related disorders. They are well tolerated over extended periods with more than 50 million people worldwide benefiting from their use. Here we show that 3 structurally distinct SSRIs--fluoxetine, paroxetine, and citalopram--act directly on Burkitt lymphoma (BL) cells to trigger rapid and extensive programmed cell death. SSRIs unexpectedly stimulated calcium flux, tyrosine phosphorylation, and down-regulation of the c-myc and nm23 genes in Burkitt lymphoma cells remaining faithful to the biopsy phenotype. Resultant SSRI-induced apoptosis was preceded by caspase activation, poly(ADP-ribose) polymerase-1 (PARP-1) cleavage, DNA fragmentation, a loss of mitochondrial membrane potential, and the externalization of phosphatidylserine, and reversed by the overexpression of bcl-2. Normal peripheral blood mononuclear cells and tonsil B cells, whether resting or stimulated into cycle, were largely resistant to SSRI-induced death as were 5 non-BL lymphoid cell lines tested. We discuss these findings within the context of whether the SSRI class of antidepressants could find future application as potential therapeutics for the highly aggressive and-because of its association with AIDS-increasingly more common Burkitt lymphoma.

High frequency of concomitant nm23-H1 and E-cadherin transcriptional inactivation in primary non-inheriting colorectal carcinomas

This study evaluated the added significance of nm23-H1 to that of E-cadherin in determining metastatic proclivity in primary sporadic colorectal carcinomas (SCRCs). A clinical cohort of 52 SCRCs was examined for the significance of nm23-H1 and E-cadherin mRNA levels and E-cadherin protein expression levels into the progression of colorectal tumor invasion, determined by their relevance compared with conventional biological markers. A more than twofold decreased expression of nm23-H1 mRNA was reported in 28/52 (54%) of the carcinomas and was positively associated with the presence of nodal metastases and Astler-Coller stages B1 and B2 in 29% and 35% of the SCRCs, respectively. Reduced expression of E-cadherin mRNA was reported in 38.5% of the carcinomas and was similarly associated with stages Astler-Coller B1 and B2 in 27% of the SCRCs. Decreased E-cadherin immunohistochemical expression (grades II and III) was observed in 67% of the samples. E-cadherin mRNA and protein expression were significantly related to each other. The nm23-H1 (+)/E-cadherin (+) coexpression profile was observed in 31% and was significantly related to the absence of lymph node metastases in 31% and stages Astler-Coller B1 and B2 in 29% of the carcinomas examined. Furthermore, the nm23-H1 (-)/E-cadherin (+) coexpression profile was coupled to decreased E-cadherin immunohistochemical protein detection (grade II) in 21% of the cases examined. These findings suggest that impairment of nm23-H1 expression is an early event into the progression of colorectal metastasis that precedes E-cadherin transcriptional silencing in the majority of SCRCs examined. Nm23-H1 may therefore play an important role in suppressing the early steps of metastasis in sporadic cases of colorectal carcinomas.

Prognostic significance of p53, nm23, PCNA and c-erbB-2 in gastric cancer

BACKGROUND

Although the TNM stage is the most important prognostic factor for gastric cancer, there is a need for new prognostic and predictive factors, because the prognosis varies among patients of the same stage. The purpose of this study was to clarify the relationship of p53, nm23, proliferating cell nuclear antigen (PCNA) and c-erbB-2 with the clinicopathological parameters and the survival results.

METHODS

For 841 patients who had undergone gastrectomy for gastric cancer at Seoul National University Hospital from July 1996 to December 1997, the expression levels of p53, nm23, PCNA and c-erbB-2 in gastric cancer tissues were examined immunohistochemically. Also, the clinicopathological parameters such as gender, age, operation type, TNM stage and size of the tumor, histology and Lauren classification were analyzed retrospectively.

RESULTS

There were 568 males and 273 females (2.07:1) with a mean age of 56 years (range:25-82 years). The percentages of positive expression of p53, nm23 and c-erbB-2 were 43, 74 and 17%, respectively; 59% of tumors expressed PCNA index > or =50. p53 expression was associated with age, gender, tumor size, histology, Lauren classification, stage, nm23 expression, PCNA index >or =50 and c-erbB-2 expression. nm23 expression was associated with age, tumor size, Borrmann type, histology, Lauren classification and stage. PCNA index > or =50 was associated with age, gender, tumor size, Borrmann type, histology, Lauren classification and c-erbB-2 expression. c-erbB-2 expression was associated with gender, Borrmann type, histology and Lauren classification. p53 and nm23 were related with poor prognosis in univariate analysis. nm23 was related with poor prognosis of stage III and diffuse-type gastric cancer in univariate subgroup analysis. However, in a multivariate study, these prognostic impacts were not maintained.

CONCLUSION

The expression of p53 and nm23 seems to be related with poor prognosis of gastric cancer patients who have undergone gastrectomy. However, the prognostic significance was not revealed by a multivariate analysis.

[Significance of p53, c-myc and nm23 protein expression in recurrent laryngeal carcinoma]

OBJECTIVE

To evaluate the prognosis of postoperative laryngeal cancer recurrence, the study was designed to investigate the relationship of p53, c-myc and nm23 protein expression in recurrent laryngeal carcinoma.

METHOD

Five hundred and seventy-four cases of laryngeal carcinoma were retrospectively reviewed. All the patients were observed for 3 years postoperatively, 56 cases with recurrence were diagnosed and 39 cases of normal laryngeal tissue were compared. The tissue microarrays was made in all the cases. The tissue chip was analyzed by the SABC immunohistochemical method.

RESULT

p53, c-myc and nm23 expressed in most of the laryngeal carcinoma. The positive ratio is different. There is higher expression of c-myc in recurrent laryngeal carcinoma, and its expression has significant difference with the laryngeal carcinoma, which have no recurrence (P < 0.01). nm23 has lower expression in recurrent laryngeal carcinoma, and it's expression has significant difference with the laryngeal carcinoma which have no recurrence(P < 0.01). The expression of p53 has no significant difference between recurrent laryngeal carcinoma and the laryngeal carcinoma which have no recurrence(P > 0.05). There is the positive correlation between the expression of c-myc and the recurrent laryngeal carcinoma; and negative correlation between the expression of nm23 and the recurrent laryngeal carcinoma.

CONCLUSION

c-myc and nm23 could be the prognosis marker of postoperative laryngeal cancer recurrence.

[Immunohistochemical study of small cell sarcomas and factors(nm23, CD44) predicting metastatic spreading in children]

An immunohistochemical study was made of 43 tumors from children, which were classified as small blue round cell tumors (13 neuroblastomas, 13 rhabdomyosarcomas, 14 Ewing sarcomas/PNET, 2 undifferentiated sarcoma, 1 rhabdoid tumor). The use of a wide panel of antibodies confirmed (in 74% of the cases) and corrected (in 26%) the diagnosis of a diversity of small cell sarcomas established by routine methods. In neuroblastoma, the occurrence of distal metastases was associated with the loss of nm 23 protein. Increase in CD44 expression was more frequently observed in neuroblastomas with favorable prognostic signs and embryonic rhabdosarcomas that are not accompanied by metastases. This needs further study.

Telomerase activity and Nm23-H2 protein expression in hepatocellular carcinoma

BACKGROUND

Telomerase activity is up-regulated in most hepatocellular carcinomas (HCCs). Nm23-H2 has been shown to promote the expression of the c-myc gene, a candidate transcriptional activator of the human telomerase reverse transcriptase gene. Therefore, this study was undertaken to clarify the relationship between nm23-H2 expression and telomerase activity in HCCs.

MATERIALS AND METHODS

Telomerase activity and nm23-H2 protein expression in 24 HCCs were analyzed by telomeric repeat amplification protocol (TRAP) assay and immunohistochemistry, respectively.

RESULTS

The incidence of positive telomerase activity was significantly higher in tumor tissues than in normal liver tissues (18 out of 24 vs. 7 out of 24, p = 0.0015), and nm23 -H2 protein was more abundantly expressed in tumors than in corresponding normal liver tissues. Tumor nm23-H2 immunoreactivity was associated positively with tumor telomerase activity (p = 0.0037).

CONCLUSION

These results demonstrate that tumor nm23-H2 expression might be associated positively with telomerase activity in HCC and suggest the value of tumor nm23-H2 linked to telomerase activity as a therapeutic target for HCC.

[The effects of conjugated linoleic acid on the expression of invasiveness and metastasis-associated gene of human gastric carcinoma cell line]

OBJECTIVES

To study the effects of c9,t11-conjugated linoleic acid (c9,t11-CLA) on invasive ability of human gastric carcinoma cell line (SGC-7901) and to explore its possible mechanism.

METHODS

Reconstituted basement membrane invasion assay was used to evaluate invasive ability of cancer cells. Expression of TIMP-1, TIMP-2 and nm23-H(1) mRNA was measured by reverse transcription polymerase chain reaction (RT-PCR) in SGC-7901 cells.

RESULTS

At the concentrations of 200 micromol/L, 100 micromol/L and 50 micromol/L, c9,t11-CLA suppressed their reconstituted basement membrane invasion of SGC-7901 by 53.7%, 40.9% and 29.3%, respectively. c9,t11-CLA could induce the expression of TIMP-1, TIMP-2 and nm23-H(1) mRNA in SGC-7901 cells.

CONCLUSIONS

The invasion of SGC-7901 cells could be inhibited by c9,t11-CLA through reconstituted basement membrane. Anti-invasion action of c9,t11-CLA might be associated with induction of expression of TIMP-1, TIMP-2 and nm23-H(1) mRNA in tumor cells.

Fluvastatin induces apoptosis in rat neonatal cardiac myocytes: a possible mechanism of statin-attenuated cardiac hypertrophy

Hydroxymethylglutaryl CoA (HMG-CoA) reductase inhibitors (statins) have been shown to reduce atherosclerotic cardiovascular mortality and morbidity. Recent evidence indicates that statins may also exert direct effects on vascular wall cells (including endothelial cells and smooth muscle cells) independently of their hypocholesterolemic properties. However, little is known about whether statins have direct effects on myocardium. The effect of lipophilic and hydrophilic statins (fluvastatin and pravastatin) on apoptosis and protein synthesis in rat neonatal cardiac myocytes was investigated. The presence of apoptosis was evaluated by morphologic criteria, electrophoresis of DNA fragments, 4",6"-diamidine-2"-phenylindole (DAPI) staining, and TUNEL assay. Protein synthesis was measured by H-leucine incorporation into the cells. Fluvastatin, but not pravastatin, induced apoptosis in cardiac myocytes in a time- and dose-dependent manner. The pro-apoptotic effect of fluvastatin was reversed in the presence of mevalonate or geranylgeranyl-pyrophosphate (GGPP), but not in the presence of squalene. The addition of protein prenylation inhibitor perillic acid and Rho-kinase inhibitor Y27632 significantly increased apoptosis. Fluvastatin decreased RhoA protein in the membrane fraction, whereas there were no significant changes of the RhoA protein in the cytosol fraction. Interleukin-1beta-stimulated H-leucine incorporation was completely inhibited by fluvastatin, but not by pravastatin. The findings suggest that fluvastatin induces apoptosis in cardiac myocytes via protein prenylation and the subsequent inhibition of Rho, and may play a role in the pathogenesis of cardiac hypertrophy and remodeling.

[The expression and significance of heparanase and nm23-H1 in hepatocellular carcinoma]

OBJECTIVE

To explore the relation between heparanase (HPA) and nm23-H1 in hepatocellular carcinoma (HCC), and judge whether they may be used as valuable markers in predicting postoperative metastasis and recurrence of HCC.

METHODS

Reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry (S-P method) were used to measure the expressions of the HPA mRNA and nm23-H1 protein in the primary tumor tissue and paracancer tissue of 33 cases of HCC. The paracancer tissues of 9 cases of benign liver tumor were used as normal controls. The results were analyzed in combination with the results of clinicopathological examination and follow-up.

RESULTS

The expression of HPA gene was positive in 16 cases of primary tumor tissues of HCC with a positive rate of 48.5%, significantly higher than those in paracancer tissues of HCC cases and in normal controls (P < 0.01). The HPA expression was not related with the size of tumor, envelope formation, AFP level, HBsAg state and cirrhosis of liver. The positive rates of HPA mRNA in the group with high tendency to metastasis or recurrence and the group with metastasis or recurrence during follow-up were significantly higher than that in the group with low tendency to metastasis or recurrence group (P < 0.05) and that in the group without metastasis or recurrence (P < 0.01). The poorly differentiated tumor and tumor of TNM stage III-IV had higher positive rates of HPA gene expression than the well-mediate differentiated tumor and tumor of TNM stage I-II (P < 0.05). The positive expression rates of nm23-Hl protein in HCC tissue was significantly lower than that in corresponding non-cancerous or normal liver tissue (P < 0.05). nm23-Hl expression was not related with the size of tumor, envelope formation, AFP level, HBsAg state, cirrhosis of liver, Edmondson grade, and TNM stage (P > 0.05). The positive rate of nm23-Hl in the group with high tendency to metastasis and recurrence and in patients with metastasis or recurrence during follow-up was obviously higher than that in the group with low tendency to metastasis and recurrence (P = 0.018) and that in the patients without metastasis and recurrence (P = 0.024), but no significant difference was found between HPA positive and negative groups (P = 0.082). According to the results of follow-up, the rates of accuracy in predicting metastasis of positive HPA, negative nm23-H1 and combination of positive HPA with negative nm23-H1 were 78.6% (11/14), 68.8% (11/16) and 88.9% (8/9) respectively.

CONCLUSION

Expression of HPA and/or nm23-Hl are related with metastasis and recurrence of HCC. Combining the expression rate of HPA with the expression rate of nm23-H1 may increase the accuracy in predicting HCC postoperative metastasis and recurrence.

[Significance of COX-2, p53, proliferating cell nuclear antigen and nm23 expressions in gastric cancer and its behavior]

BACKGROUND & OBJECTIVE

Molecular biological studies indicated that abnormal expression of cyclooxygenase-2(COX-2), p53, proliferating cell nuclear antigen(PCNA), and nm23 correlate with the development of gastric cancer, but the relationship between abnormal expression of above gene proteins and the biological behavior of gastric cancer was not yet clear. This study was designed to investigate the relationship between expressions of COX-2, p53, PCNA, and nm23 and the clinicopathological behavior in gastric cancer.

METHODS

The expressions of COX-2, p53, PCNA, and nm23 were detected by using immunohistochemical(SP) method.

RESULTS

(1) The overexpression rate of COX-2 in gastric cancer was 70.4% (50/71), and the overexpression of COX-2 was correlated to tumor size, gross morphology, histological type, lymph node metastases, and clinicopathological stage of gastric cancer (P < 0.05, or P < 0.01). (2) The overexpression rates of p53 and PCNA in 71 surgically removed specimens from the patients with gastric cancer were 74.6% and 78.9%, respectively. And the expressions of p53 (86.7%) and PCNA (88.8%) in gastric cancer patients with lymph node metastasis were significantly higher than those in patients without lymph node metastasis (53.8% and 61.5%) (both, P < 0.05), respectively. Moreover, expressions of p53(52.2%) and PCNA(60.9%) in stage I + II patients were lower than those(85.4% and 87.5%) in stage III + IV (both, P < 0.05). (3) The low-expression of nm23 in gastric cancer was 71.8%, and its low-expression rate of nm23 in patients without lymph node metastasis(88.5%) and in stage I + II (91.3%) were much higher than those in the patients with lymph node metastasis (62.2%) and in stage III + IV (62.5%) (respectively, P < 0.05). (4) The differences of histological types, depth of invasion, lymph node metastasis and clinical stage were significantly different(P < 0.05 or P < 0.001), between the patients with two or more genes expression of COX-2, p53, PCNA, and nm23 and those with less one gene expression.

CONCLUSION

Our results suggest that abnormal expressions of COX-2, p53, PCNA, and nm23 associate with malignant potential, lymph node metastasis and clinical stage, and they might therefore play a role in development of gastric cancer.

The relationship between expression of c-ras, c-erbB-2, nm23, and p53 gene products and development of trophoblastic tumor and their predictive significance for the malignant transformation of complete hydatidiform mole

OBJECTIVE

The aims of this retrospective study by means of immunohistochemical staining were (1) to study the expression of c-ras, c-erbB-2, p53, and nm23 gene products in complete hydatidiform moles that progress to gestational trophoblastic tumor and in those that remit spontaneously after evacuation, and (2) to estimate the predictive value of the expression of these four gene products in malignant transformation of complete hydatidiform mole.

METHODS

Clinical data of patients with complete hydatidiform mole were obtained by retrospective chart review. Formalin-fixed paraffin sections of 50 cases of complete mole that progressed to gestational tumor and 32 cases of complete mole that remitted spontaneously were studied immunohistochemically for c-ras, c-erbB-2, p53, and nm23 proteins. The prognostic value of the proteins for the malignant transformation of complete mole was analyzed by multiple logistic regression and stepwise logistic estimation. Sections of 30 cases of invasive mole and 19 cases of choriocarcinoma were also immunohistologically studied for expression of the proteins.

RESULTS

Expression of c-erbB-2 and p53 gene products was significantly increased and expression of nm23 and c-ras products was remarkably decreased in complete hydatidiform moles that progressed into postmolar tumor compared with those that remitted spontaneously after evacuation. There was no significant difference in the expression of the four genes in invasive mole and in choriocarcinoma. A logistic estimation model for predicting malignant transformation of complete mole was established based on the expression of gene products. When the expression of four gene products was used, the predictive sensitivity of the regression model was 86.0%, and the specificity was 75.0%. The positive predictive value was 84.3%, the negative predictive value was 77.4%. Logistic stepwise regression analysis showed that the altered expression of c-erbB-2 and nm23 products had strong predictive value, while the expression of c-ras and p53 products had no significant predictive value for the malignant transformation of complete mole.

CONCLUSION

The altered expression of c-ras, c-erbB-2, nm23, and p53 gene products may be important in the pathogenesis of gestational trophoblastic tumor. The decreased expression of nm23 protein and increased expression of c-erbB-2 protein are strong predictors for the malignant transformation of complete mole.

Prognostic significance of CD44v6 and nm23 protein immunoexpression in laryngeal squamous cell carcinoma

In several tumours expression of CD44 and nm23 protein has been linked to tumour progression and metastasis. The aim of this study was to determine if there is any relationship between CD44v6 and nm23 protein immunoreactivity in squamous cancer cells and prognosis in patients with laryngeal carcinoma. The samples of human larynx cancer from patients with lymph node metastases and without lymph node involvement were analysed for CD44v6 and nm23 protein expression by immunohistochemistry using monoclonal antibodies. There was no significant difference in CD44v6 immunoexpression in cancer cells in patients with and without metastases. The statistical analysis did not reveal difference in survival time between patients with high and low CD44v6 immunoreactivity. The expression of nm23 protein in laryngeal cancer in patients with lymph node metastases was significantly decreased in comparison with patients without metastases. Analysis of survival revealed that patients with lower expression of nm23 protein in tumour tissue had significantly shorter survival than patients with higher nm23 immunoreactivity. The results suggest that nm23 protein immunoreactivity can be useful in predicting tumour behaviour in laryngeal cancer patients and indicate a lack of association between CD44v6 immunoexpression and tumour progression in those patients.

MMTV-associated transcription factor binding sites increase nm23-H1 metastasis suppressor gene expression in human breast carcinoma cell lines

We hypothesize that elevation of nm23-HI metastasis suppressor gene expression in micrometastatic tumor cells may reduce their subsequent colonization and invasion, and induce differentiation, with a clinical benefit. This report presents the first analysis of the nm23-HI promoter to identify sites which can increase its transcription. Deletion mapping of a 2.1 kb nm23-H1 promoter fragment tethered to a reporter gene identified three regions involved in its differential expression levels among a panel of human breast carcinoma cell lines: a 195 bp NheI-XbaI fragment responsible for basal expression levels, a 248 bp AvrII-Nhel fragment which contributed to the elevated nm23-H1 expression observed in the high expressing cell lines, and a 544 bp AvrII fragment containing an inhibitory element. Examination of the 248 bp AvrII-NheI fragment revealed the unexpected presence of three transcription factor binding sites (MAF/Ets, CTF/NF1 half site and ACAAAG enhancer) previously identified in the MMTV-LTR, and in WAP and milk gene promoters, proposed to mediate mammary-specific gene expression. Mutation of the three sites, individually or together, resulted in two-fold reductions in reporter gene expression. As controls, the same panel of mutations caused a different pattern of reporter gene expression in a non-mammary cell line, and mutation of another nearby site was without effect on nm23-HI. Our data identify a complex regulatory pattern for nm23-H1 transcription, and suggest that a mammary-specific cassette of transcription factors contribute to its elevated expression

[Primary study of arsenic trioxide inhibits abdomino-metastatic tumor formation of human ovarian carcinoma in nude mice and its mechanisms]

BACKGROUND AND OBJECTIVE

Arsenic trioxide (As2O3) has been successfully used to treat the patients with acute promyelocyutic leukemia in clinic, and for the experimental studies of liver cancer, colorectal cancer, gastric cancer, etc. The objective of this study was to explore the inhibitory effect of As2O3 on the abdomino-metastasis of human ovarian carcinoma in nude mice and its mechanisms.

METHODS

Compared with cisplatin(cDDP), the growth inhibiting rates to human ovarian cancer cell line 3AO by treatment with various concentrations of As2O3 for 48 h were determined by methyl thiazolyl tetrazolium(MTT) method. After implanted with 3AO cells 4 x 10(6) into abdominal cavity for 96 h, the nude mice were randomly divided into 5 groups and treated by intraperitoneal injection of normal saline, cisplatin, or different concentrations of As2O3. The rate of tumor formation, death rate, and survival period of tumor-bearing nude mice were evaluated. After treatment with As2O3, the changes of Fas, FasL, and nm23 gene expressions were estimated by flow cytometry (FCM).

RESULTS

Compared with cisplatin, 3AO cell growth inhibiting rates by As2O3 were different significantly in concentration-dependent manner (P < 0.05); Compared with cisplatin, As2O3 could reduce the 3AO cell tumor formation rate in nude mice and the death rate of tumor-bearing nude mice, and prolong the survival period of tumor-bearing nude mice significantly (P < 0.05). As2O3 up-regulated Fas and nm23 gene expressions of abdominal cavity implanted tumors (P < 0.05), but did not affect FasL gene expression (P > 0.05).

CONCLUSION

As2O3 could inhibit the abdomino-plantation of human ovarian carcinoma in nude mice and its mechanism may be associated with Fas gene and nm23 gene over-expressions.

[Angiogenesis and the expression of nm23-H(1) tumor metastatic suppressor gene in primary breast carcinoma and their relations to lymph node metastasis]

OBJECTIVE

To study angiogenesis and the expression of nm23-H(1) tumor metastatic suppressor gene in primary breast carcinoma and their relationship with axillary lymph node metastasis.

METHODS

Intratumoral vascularization in 80 cases of breast cancer was observed preoperatively by power doppler imaging (PDI) and analysed with computer-assisted quantative assessment, and the expression of microvessel density (MVD) and nm23 protein was determined by immunohistochemical technique.

RESULTS

Blood flow signals and blood vessels postitive area within masses were more in axillary node positive (LN+) group than in axillary node negative (LN-) group (t = 7.07, P < 0.01), MVD expression were higher in the LN+ group than in the LN- group (t = 6.34, P < 0.01). Meanwhile the expression of nm23-H(1) protein was lower in the LN+ group than in the LN- group, and significant correlation was found between angiogenesis and the expression of nm23-H(1) protein.

CONCLUSIONS

Angiogenesis and the expression of nm23-H(1) protein may play an important role in the lymphatic metastasis process of breast cancer. Furthermore, angiogenesis may correlates with the expression of nm23-H(1) protein in that progress.

Activation of antimetastatic Nm23-H1 gene expression by estrogen and its alpha-receptor

Metastasis of various malignant cells is inversely related to the abundance of the Nm23-H1 protein. The role of estrogens in tumor metastasis has now been investigated by examining the effect of E2 on the expression of the Nm23-H1 gene. Three human breast carcinoma cell lines, in which endogenous ERalpha is expressed at different levels, were used as a tool to assess the role of ERalpha in Nm23-H1 gene-mediated metastasis. E2 induced time-dependent increases in the abundance of Nm23-H1 mRNA and protein, with the extent of these effects correlating with the level of expression of ERalpha. E2 induced a marked decrease in the invasive activity of MCF-7 and BT-474 cells but had no effect on BCM-1 cells, which had virtually no ERalpha. Consistent with these results, the ER-mediated Nm23-H1 promoter activity was inhibited 3-fold by the E2 antagonist, ICI 182,780. Deletion analysis of the promoter region of the Nm23-H1 gene identified a positive estrogen-responsive element located in -108/-94. ER protein bound specifically to the -108/-79 fragment with high avidity. These results indicate that E2, acting through ERalpha, activated transcription of the Nm23-H1 gene via a positive estrogen-responsive element in the promoter region of the gene. These results suggest that E2 could suppress tumor metastasis by activating the expression of the Nm23-H1 gene.

[Alteration of multiple tumor metastatic genes with correlation to metastasis in ovarian carcinoma]

OBJECTIVE

To investigate the expression and mutation of MTA1, nm23H1 and E-cadherin(E-cad) genes in ovarian carcinoma (OC) in relation to lymph node (LN) metastasis.

METHODS

A panel of normal ovarian tissues, primary OC specimens and corresponding LNS was examined for mRNA expression and mutation of MTA1 and nm23H1 and protin expression of E-cad genes by using RT-PCR, RT-PCR-SSCP and immunohistochemistry.

RESULTS

The frequency of MTA1 over expression was 100%(7/7) in primary OC with metastasis but only 38.5%(5/13) in those without metastasis (P = 0.0103). Overexpression of MTA1 was observed in 87.5%(6/7) of LNS with metastasis but in only 23%(3/13) of LNS without metastasis (P = 0.0118). In contrast with MTA1, low expression of nm23H1 mRNA was seen in 7 of 7 OC with metastasis but only in 4 of 13(30%) of those without metastasis (P = 0.0043). Low nm23H1 expression was also seen in 7 of 7 LNS with metastasis but only in 5 of 13 (38.5%) nonmetastatic LNS (P = 0.0102). Meantime, no expression of E-cad protein was observed in 7 of 7 OC with metastasis but in 6 of 13(46.2%) of those without metastasis (P = 0.044). In correlation analysis of the three genes, MTA1 reversely correlated with nm23H1 and E-cad respectively (r = -0.903, -0.803), and positive correlation existed between nm23H1 and E-cad (r = 0.724). No mutation of MTA1, nm23H1 and was found by SSCP analysis.

CONCLUSION

The mRNA expression of MTA1, nm23H1 and E-cad is positively and negatively correlated with LN metastasis. The expression abnormalities but not the mutations of the three genes are frequent events related to LN metastasis of ovarian cancer.

Regulation of Dexras1 expression by endogenous steroids

Dexras1, a newly identified member of the Ras superfamily of proteins, was discovered in AtT-20 corticotrope cells because its expression was induced in response to glucocorticoids (dexamethasone; Dex). As yet, the function of Dexras1 is unknown, but its rapid induction in response to glucocorticoids suggests the possibility that it may be involved in negative feedback regulation of corticotropin secretion. To better understand the control of Dexras1 expression, possible effects of other steroid hormones on its expression were studied in both AtT-20 cells and in mouse pituitaries. AtT-20 cells were treated with each of 6 steroids [aldosterone, corticosterone (Cort), Dex, beta-estradiol (E(2)), progesterone and testosterone] for 2 h. Dexras1 expression was assessed using both reverse transcription polymerase chain reaction (RT-PCR) and Northern analysis. Expression of the gene was only induced in response to glucocorticoid treatment (Dex or Cort). The 6 steroids were also injected into mice, pituitaries were harvested and total RNA was obtained for RT-PCR analysis. Surprisingly, treatment with E(2), not only injection of glucocorticoids, induced Dexras1 expression in mouse pituitary. Other steroids were without effect. The results suggest that in AtT-20 corticotropes, Dexras1 expression is only induced by glucocorticoid-type steroids. In pituitary glands of mice, the gene's expression is also responsive to E(2). We conclude that either Dexras1 expression in corticotropes from normal mice is regulated differently from that in AtT-20 cells, or that Dexras1 is also expressed in other pituitary cells than corticotropes.

PTCH gene altered in dentigerous cysts

Motivated by the evidence that odontogenic keratocysts are associated with genetic alterations, we examined the possibility that development of other odontogenic cysts can be attributed to gene malfunctioning, in particular to the PTCH gene. Cyst epithelium was examined for polymorphism on chromosome 9q22.3, the region that contains the PTCH gene. Loss of heterozygosity (LOH) for the D9S287 marker and/or D9S180 marker was observed in about 50% of dentigerous cysts, whereas radicular cysts gave no indication of lesions in the PTCH region. As a more direct argument for PTCH involvement in cystic growth, we report evidence of PTCH expression in dentigerous cyst lining, which indicates malfunctioning of the relevant signaling pathway. While we found no reason to believe that PTCH should be associated with radicular cysts, other genes may be implicated in their development. We performed immunohistochemical comparisons of keratocysts, dentigerous and radicular cysts for the nonmetastatic marker Nm23. A graded response placed radicular cysts in between the other two types, suggesting a similar neoplastic character for their epithelial proliferation.

Expression of nm23 gene in gastric cancer is associated with a poor 5-year survival

The nm23 gene is thought to play a role as an inhibitor of metastatic progression in several human cancers and its down-regulation has been associated with increased metastasis and reduced survival in some studies, though not in others. To better investigate the role of nm23 in gastric cancer (GC), the expression and prognostic impact of this gene was examined in 107 radically operated GC patients in a high risk area. The expression of nm23 was determined immunohistochemically by using the rabbit antibody anti-human nm23 protein. The expression of nm23 was detected in 40.2% (n = 43) of 107 gastric tumours and correlated with a poorer clinical outcome. In a survival analysis at 5 years, patients with nm23-positive tumours had significantly worse prognosis than patients (n = 64) with nm23-negative tumours (p < 0.05). The prognostic significance of nm23 expression was confirmed by multivariate analysis including terms for tumour stage and lymph node involvement. Our results suggest that the expression of the nm23 gene in gastric carcinoma is significantly related to tumour progression and poor prognosis at 5 years.

[Detection of proteins and mRNA of p16, p53 and nm23 in mucoepidermoid carcinoma of salivary glands and their prognostic significance]

OBJECTIVE

To disclose the relationship between the expression of p16, p53 and nm23 and the significant morphologic characteristics in mucoepidermoid carcinoma.

METHODS

The proteins and mRNA in paraffin blocks from 41 mucoepidermoid carcinoma patients were studied with immunohistochemical methods and in situ hybridization respectively.

RESULTS

The negative expression of p16 was found in 62.5% (15/24) of the low differentiation grade and in 29.4% (5/17) of the high differentiation grade (P = 0.037). The positive p53 expression was detected in 70.8% (17/24) of the low grade neoplasms and in 23.5% (4/17) of the high grade (P = 0.003), while positive nm23 protein was present in 37.5% (9/24) and 64.7% (11/17) respectively (P = 0.086). However, no relationship was found between positive mRNA of p16, p53, nm23 and WHO pathologic grade.

CONCLUSIONS

There is a significant correlation between expression of p16 and p53 and WHO pathologic grade of mucoepidermoid carcinoma, which indicates clinical prognostic significance. No correlation is noticed between the pathologic grade and the expression of nm23 protein and mRNAs of p16, p53 and nm23.

Prognostic value of nm23 expression in stage IB1 cervical carcinoma

BACKGROUND

The purpose of this retrospective study was to evaluate the patterns of nm23 expression in stage IB1 squamous cell carcinoma of the uterine cervix, to compare nm23 expression with clinicopathological findings and to assess its prognostic value.

METHODS

Twenty-seven patients with stage IB1 squamous cell carcinoma of the uterine cervix underwent abdominal radical hysterectomy and pelvic lymph node dissection. Expression of nm23 was studied immunohistochemically, followed by amplification and direct sequencing of exons 4 and 5 of the nm23 gene.

RESULTS

Overexpression of nm23 was detected in 18.5% of the tumors and low expression was seen in 33.3%, while negative expression was found in 48.1% of the tumors. Deep cervical stromal invasion (> or =1/2) was found to be associated with the increased risk of lymph node metastases (odds ratio = 17.5). A significantly lower percentage of patients survived when nm23 overexpression was observed (p = 0.0063). Univariate analysis revealed that tumor size (2-3.9 cm), lymph node metastasis, tumor invasion into parametria, tumor invasion into blood/lymph vessel, squamous cell carcinoma (> or =2 ng/ml) and nm23 overexpression had a significantly lower recurrence-free survival rate of the patients. None of the above factors was significant according to multivariate analysis. There were no mutations in exons 4 and 5 of the nm23 gene in stage IB1 squamous cell carcinoma of the uterine cervix.

CONCLUSIONS

This study suggests that expression of nm23 may be indicative of an unfavorable prognosis in patients with stage IB1 squamous cell carcinoma of the uterine cervix.

Overexpression of nm23-H4 RNA in colorectal and renal tumours

A new member of the nm23 gene family, designated nm23-H4, was cloned recently. Nm23-H4 is a mitochondrial protein. To determine whether nm23-H4 could have a function in tumour progression like nm23-H1 or nm23-H2, we analysed nm23-H4 expression in 18 renal tumours and 42 colorectal carcinomas obtained from patients who underwent curative resection. As compared to the corresponding healthy tissue, 14 renal tumours and 41 colorectal carcinomas showed increased nm23-H4 mRNA expression. While the increase was only moderate in renal cell carcinoma, a strong overexpression of nm23-H4 was noted in most colorectal carcinomas, possibly indicating a role of this gene in tumour genesis. The nm23-H4 transcript levels did not correlate with tumour stage, grade of differentiation or lymph node involvement.

[Expression of nm23 in breast cancer: correlation with distant metastasis and prognosis]

OBJECTIVE

To investigate the relationship between expression of nm23 gene and distant metastasis and prognosis in breast cancer.

METHODS

To detect nm23 protein expression in 101 patients with breast cancer by means of immunohistochemistry and nm23 mRNA expression in 68 patients with breast cancer by RT-PCR.

RESULTS

Expression of nm23 gene was inversely correlated with distant metastasis and lymph node metastasis. Among 9 patients with negative node but with distant metastasis, 7 had low expression of nm23. In 29 patients with positive nodes but without distant metastasis, 24 had high expression of nm23, while 6 of 6 patients with positive nodes and distant metastasis expressed high levels of nm23 mRNA.

CONCLUSION

Expression of nm23 gene, tumor size and status of axillary lymph node are independent prognostic indicators to breast cancer prognosis.