Cell Surface Nucleolin Research Articles

Breaking the malignant triangle in glioblastoma - ErbB1/nucleoin/Ras

Glioblastoma is one of the most malignant tumors in humans, with poor diagnosis and a low survival rate. These tumors overexpress the ErbB1 receptor and have high levels of cell surface nucleolin, which serves as an indicator for disease grade. We have previously identified a crosstalk between three oncogenes: ErbB1, Ras and nucleolin. This lead us to suggest a combined treatment using FTS, to target Ras protein, and GroA, to target cell surface nucleolin, in order to break this malignant synergy. Here we review our recent findings and suggest a model explaining drugs activities: inhibition of Ras using FTS mainly reduces cell viability and motility and inhibition of nucleolin using GroA reduces the cell proliferation. The combined treatment has a more pronounced effect on glioblastoma growth.

Functionalization of Iron Oxide Magnetic Nanoparticles with the Multivalent Pseudopeptide N6l for Breast Tumor Targeting

Functionalized iron oxide magnetic nanoparticles (MNP) are an innovative tool for cancer detection and treatment. In this study, a cell-surface nucleolin antagonist, N6L, was used as targeting ligand for MNP. This N6L, which exhibits antitumor activities, specifically targets bind tumor cells by binding to cell-surface nucleolin and glycosaminoglycans. N6L was covalently conjugated to dimercaptosuccinic acid coated magnetic nanoparticles (MNP-N6L). Using immunoprecipitation, gene invalidation and enzymatic degradation of glycosaminoglycans, we showed that MNP-N6L targets human breast cancer MDA-MB 231 cells through interaction with nucleolin and sulfated glycosaminoglycans. In vivo biodistribution studies were carried out in MDA-MB 231 tumor-bearing mice, using iron detection assay by spectrometric analysis and Prussian blue staining. Whereas both non-functionalized and functionalized nanoparticles were found in liver and spleen, only MNP-N6L was found in the tumor. Our findings indicate that MNP-N6L is a promising targeting system for theranostic applications in cancer detection and treatment.

Nanoparticles Functionalized with Ligands of Cell Surface Nucleolin for Cancer Therapy and Diagnosis

Conventional cancer chemotherapies are often limited by their non-targeted nature and their inadequate delivery to the tumor affecting the normal tissues and leading to toxic adverse effects. In order to improve the anticancer efficacy and safety of these drugs, as well as the diagnosis capacity of imaging agents, nanoparticles drug delivery system has been developed combining ligands enabling tumor targeting at a cellular level and drug carrier capacity. Nucleolin (NCL) is a multifunctional protein that could shuttle from nucleolus to nucleoplasm, cytoplasm and cell surface. This ribonucleo protein over expressed at the cell surface of cancer cells is involved in many cancer processes supporting tumorigenesis such as cell proliferation and apoptosis. Additionally, NCL expression is enhanced in angiogenic vessels, enabling multi-targeting strategies toward the tumor microenvironment. In this context, several compounds targeting NCL, such as the aptamer AS1411, the peptide F3 and the multivalent pseudopeptide N6L, have been developed and investigated for cancer therapy. Due to their cancer cell targeting capacities, these compounds have been evaluated to mediate highly specific and effective nanoparticles for drug delivery to the tumor. In this report, we present a review of literature focusing on drug-loaded nanoparticles conjugated with these nucleolin ligands, strikingly emphasizing the success of such a strategy.

Respiratory syncytial virus receptor expression in the mouse and viral tropism.

Human respiratory syncytial virus (RSV) infects airway epithelium and can cause serious illnesses such as bronchiolitis and pneumonia. With the discovery of cell-surface nucleolin as a fusion receptor for RSV, the question arose as to whether nucleolin could explain RSV tropism in vivo. Here, we report the distribution of cell-surface nucleolin expression in tissues of normal mice and how this distribution of expression relates to what is known about RSV tropism and its clinical manifestations. Our results show evidence of cell-surface nucleolin expression in the respiratory tract. In addition, cell-surface nucleolin is expressed in tissues outside of the respiratory tract, many of which correspond to previous reports of tissue-specific RSV infection, and others that may allude to additional potential sites for RSV infection in vivo. Furthermore, our work provides a foundation for the investigation of nucleolin's physiological function in various healthy mammalian tissues.

Cell surface nucleolin interacts with CXCR4 receptor via the 212 c-terminal portion.

Previously, we reported that CXCR4 receptor interacted with cell surface nucleolin, and the synergy of CXCR4 and nucleolin plays an essential role in malignant transformation. Here, we continued to conduct a structure-function analysis of nucleolin to identify which portion can efficaciously bind to CXCR4. In the present study, the expression of CXCR4 and nucleolin in 100 cases of papillary thyroid cancer (PTC) samples was investigated through immunohistochemistry (IHC). Subsequently, using nucleolin mutants and pull-down assay, we investigated precise interactions between CXCR4 and nucleolin in HEK-293 cells. A previous study demonstrated CXCR4 and nucleolin co-expressed in cell lines, and the present study further identified that CXCR4 and nucleolin co-expressed in PTC tissues, instead of normal tissues. The nucleolin mutant analysis revealed that nucleolin can efficaciously bind CXCR4 to activate CXCR4 signaling by 212 C-terminal domain. Conversely, N-terminal, RBD and GAR mutants of nucleolin showed no sign of activation of CXCR4 signaling, and differences were statistically insignificant (p > 0.05). In conclusion, these results suggested nucleolin is essential to activate CXCR4 signaling via 212 C-terminal domain, which is required for cell growth, migration, and invasiveness. Furthermore, nucleolin may interact with more G protein-coupled receptors, at least chemokine receptor. Our study will lay a new foundation for cancer therapy by antagonizing nucleolin and CXCR4.

749: Targeting cell-surface nucleolin in metastatic breast cancer

749: Targeting cell-surface nucleolin in metastatic breast cancer

Phosphorylation and changes in the distribution of nucleolin promote tumor metastasis via the PI3K/Akt pathway in colorectal carcinoma

Here, we investigated the molecular mechanism underlying the changes in the distribution of nucleolin. Our study identified PI3K/Akt signaling as an essential pathway regulating the distribution of nucleolin. Furthermore, nucleolin can interact with phospho-PI3K-p55, and changes in the distribution of nucleolin were related to its phosphorylation. Subsequently, we analyzed the correlation of VEGF and nucleolin, and found that distribution of nucleolin related to metastatic potential. Finally, blocking cell surface nucleolin influences the process of epithelial-mesenchymal transitions. This indicates that nucleolin may be a novel cancer therapy target and a predictive marker for tumor migration in colorectal carcinoma.

Cell Surface Nucleolin as a Target for Anti-Cancer Therapies

A large number of mostly recent reports show enhanced expression of the multi-functional protein nucleolin (NCL) on the surface of activated lymphocytes, angiogenic endothelial and many different types of cancer cells. Translocation of NCL at the external side of the plasma membrane occurs via a secretory pathway independent of the endoplasmic reticulum-Golgi complex, requires intracellular intact actin cytoskeleton, and seems to be mediated by a variety of factors. Cell surface NCL serves as a binding partner of several molecules implicated in cell differentiation, adhesion, and leukocyte trafficking, inflammation, angiogenesis and tumor development, mediating their biological activities and in some cases, leading to their internalization. Accumulating evidence validates cell surface NCL as a strategic target for treatment of cancer, while its property of tumor-specific uptake of targeted ligands seems to be useful for the development of non-invasive imaging tools for the diagnosis of cancer and for the targeted release of chemotherapeutic drugs. The observation that cell surface NCL exists in complexes with several other proteins implicated in tumorigenesis and angiogenesis suggests that targeting cell surface NCL might trigger multi-inhibitory effects, depending on the cell type. This review summarizes papers and patents related to the redistribution and the biological functions of cell surface NCL, with emphasis on the potential importance and advantages of developing efficient anti-cell surface NCL strategies.

RETRACTED ARTICLE: Nucleolin Promotes TGF-β Signaling Initiation via TGF-β Receptor I in Glioblastoma

The transforming growth factor β (TGF-β) pathway plays a key role in oncogenesis of advanced cancers, involving the non-Smad and Smad pathways. Meanwhile, nucleolin on the cell surface has been also reported to affect activation of signaling pathways. However, the effect of cell surface nucleolin on TGF-β pathway in glioblastoma is not still understood. Here, using antibodies of nucleolin and TGF-β receptor I (TβR-I), we observed blocking of either nucleolin or TβR-I inhibited the phosphorylation of CrkL, Erk1/2, and Smad2. Using nucleolin siRNA, nucleolin knockdown was also identified to suppress the expression of p-CrkL, p-Erk1/2, and p-Smad2. Furthermore, immunoprecipitation revealed the interaction between cell surface nucleolin and TβR-I on the U87 cell membrane. In addition, U87 cell wound-healing, soft-agar and MTT assay also showed si-nucleolin could obviously impair wound closure (p < 0.001), colony formation (p < 0.001) and cell growth (p < 0.001). In conclusion, nucleolin promotes and regulates the TGF-β pathway by interacting with TβR-I and is required for initiation and activation of TGF-β signaling. Thus, nucleolin could be a key factor in glioblastoma pathogenesis and considered a therapeutic target, which may also mediate more signaling pathways.

Cell-surface nucleolin acts as a central mediator for carcinogenic, anti-carcinogenic, and disease-related ligands

Purpose Cell-surface nucleolin in human gastric cancer cell lines is a receptor for TNF-α-inducing protein (Tipα) of Helicobacter pylori. The binding complex of nucleolin and Tipα is internalized into the cells and then induces tumor progression of human gastric cancer. Surface nucleolin is also a receptor of human immunodeficiency virus-1, and the anti-HIV pseudopeptide (HB-19) showed anti-carcinogenic activity in vivo. Surface nucleolin has dual functions depending on the ligands: In order to understand the mechanisms of surface nucleolin, it is necessary to review surface nucleolin and its relation to carcinogenic ligands and anti-carcinogenic ligands. Other ligands can be grouped among disease-related ligands, which is an important new topic for the prevention of various ailments. Results and discussionThis paper mainly deals with two ligands of surface nucleolin, Tipα and pseudopeptide HB-19. The binding complex of nucleolin and Tipα induces expression of TNF-α and chemokine genes and activates NF-κB in gastric cancer cells of humans and mice. However, when human gastric cancer cell line MKN-1 was transfected with nucleolin-targeted siRNA, the result was inhibition of cell migration and elongation induced by Tipα. The amount of surface nucleolin was reduced in membrane fraction of the nucleolin knockdown MKN-1 cells, but the amount of nucleolin in the cytosol or nuclear fractions of the cells did not change. The results indicate that surface nucleolin acts as a carcinogenic mediator for Tipα of H. pylori. In contrast, both the viral external envelop glycoprotein gp120 of HIV and the anti-HIV pseudopeptide HB-19 bind to surface nucleolin. Through this binding, treatment with HB-19 inhibited tumor development in human breast cancer cell line MDA-MB-231 and rhabdoid tumor cell line derived from Wilms’s tumor in xenograft nude mouse models. The results show that surface nucleolin acts as an anti-carcinogenic mediator for HB-19.ConclusionBased on these discrete functions of surface nucleolin, the binding complex of carcinogenic ligands and surface nucleolin seems to be competing with that of anti-carcinogenic ligands and surface nucleolin. Moreover, carcinogenic ligands derived from endogenous sources play a significant role in human cancer development, and the interaction of surface nucleolin with disease-related ligands will be a new research subject for the prevention and treatment of various ailments.

Nucleolin Targeting AS1411 Modified Protein Nanoparticle for Antitumor Drugs Delivery

Over recent years, cell surface nucleolin as an anticancer target has attracted many researchers' attentions. To improve the antitumor efficacy, we developed a nucleolin targeted protein nanoparticle (NTPN) delivery system in which human serum albumin (HSA) was used as drug carrier and a DNA aptamer named AS1411, which had high affinity to nucleolin, was used as a bullet. The HSA nanoparticles (NPs-PTX) were fabricated by a novel self-assembly method and then modified with AS1411 (Apt-NPs-PTX). The resulted Apt-NPs-PTX were spherical. Compared with NPs-PTX, the uptake of Apt-NPs-PTX displayed a significant increase in MCF-7 cells while there was a decrease in nontumor cell lines such as MCF-10A and 3T3 cells. In a cytotoxic study, Apt-NPs-PTX displayed an enhanced cytotoxicity in MCF-7 tumor cells while there was almost no cytotoxicity in MCF-10A cells. Endostatin, a nucleolin inhibitor, could significantly decrease the internalization of Apt-NPs-PTX, suggesting nucleolin mediates the transmembrane process of Apt-NPs-PTX. Therefore, the AS1411 modified NTPN delivery system might be a promising targeted drug delivery system.

Cell surface nucleolin is crucial in the activation of the CXCL12/CXCR4 signaling pathway

Recently, CXCL12-CXCR4 has been focused on therapeutic strategies for papillary thyroid carcinoma (PTC) and other cancers. At the same time, cell surface nucleolin is also over-expressed in PTC and others. Interestingly, a few reports suggest that either CXCR4 or cell surface nucleolin is a co-receptor for HIV-1 entry into CD4+ T cells, which indicates that there is a relationship between CXCR4 and nucleolin. In this study, antibody and siRNA were used to identify effects of cell surface nucleolin and CXCR4 on cell signaling; soft-agar colony formation assay and Transwell assay were used to determine roles of nucleolin and CXCR4 in cell proliferation and migration. Importantly, co-immunoprecipitation was used to demonstrate the relationship between CXCR4 and nucleolin. Results showed CXCR4 and nucleolin were co-expressed in PTC cell line K1, B-CPAP, and TPC-1. Either cell surface nucleolin or CXCR4 was necessary to prompt extracellular signal-regulated kinase phosphorylation. When blocked, CXCR4 or nucleolin can significantly affect TPC-1 proliferation and migration (p < 0.01). Co-immunoprecipitation analysis identified that nucleolin can bind and interact with CXCR4 to activate CXCR4 signaling. This study suggests that nucleolin is crucial in the activation of CXCR4 signaling, which affects cell growth, migration, and invasiveness. Further, nucleolin may interact with other receptors. Our study also offers new ideas for cancer therapy.

Nucleolin inhibits Fas ligand binding and suppresses Fas-mediated apoptosis in vivo via a surface nucleolin-Fas complex

AbstractResistance to Fas-mediated apoptosis is associated with poor cancer outcomes and chemoresistance. To elucidate potential mechanisms of defective Fas signaling, we screened primary lymphoma cell extracts for Fas-associated proteins that would have the potential to regulate Fas signaling. An activation-resistant Fas complex selectively included nucleolin. We confirmed the presence of nucleolin-Fas complexes in B-cell lymphoma cells and primary tissues, and the absence of such complexes in B-lymphocytes from healthy donors. RNA-binding domain 4 and the glycine/arginine-rich domain of nucleolin were essential for its association with Fas. Nucleolin colocalized with Fas on the surface of B-cell lymphoma cells. Nucleolin knockdown sensitized BJAB cells to Fas ligand (FasL)-induced and Fas agonistic antibody-induced apoptosis through enhanced binding, suggesting that nucleolin blocks the FasL–Fas interaction. Mice transfected with nucleolin were protected from the lethal effects of agonistic anti-mouse Fas antibody (Jo2) and had lower rates of hepatocyte apoptosis, compared with vector and a non-Fas-binding mutant of nucleolin. Our results show that cell surface nucleolin binds Fas, inhibits ligand binding, and thus prevents induction of Fas-mediated apoptosis in B-cell lymphomas and may serve as a new therapeutic target.

Interplay between αvβ3 Integrin and Nucleolin Regulates Human Endothelial and Glioma Cell Migration

The multifunctional protein nucleolin (NCL) is overexpressed on the surface of activated endothelial and tumor cells and mediates the stimulatory actions of several angiogenic growth factors, such as pleiotrophin (PTN). Because α(v)β(3) integrin is also required for PTN-induced cell migration, the aim of the present work was to study the interplay between NCL and α(v)β(3) by using biochemical, immunofluorescence, and proximity ligation assays in cells with genetically altered expression of the studied molecules. Interestingly, cell surface NCL localization was detected only in cells expressing α(v)β(3) and depended on the phosphorylation of β(3) at Tyr(773) through receptor protein-tyrosine phosphatase β/ζ (RPTPβ/ζ) and c-Src activation. Downstream of α(v)β(3,) PI3K activity mediated this phenomenon and cell surface NCL was found to interact with both α(v)β(3) and RPTPβ/ζ. Positive correlation of cell surface NCL and α(v)β(3) expression was also observed in human glioblastoma tissue arrays, and inhibition of cell migration by cell surface NCL antagonists was observed only in cells expressing α(v)β(3). Collectively, these data suggest that both expression and β(3) integrin phosphorylation at Tyr(773) determine the cell surface localization of NCL downstream of the RPTPβ/ζ/c-Src signaling cascade and can be used as a biomarker for the use of cell surface NCL antagonists as anticancer agents.

Regulation of Fas-mediated Apoptosis in B-Cell Lymphomas by Nucleolin.

Abstract 2406The death receptor Fas has a key role in mediating homeostasis, elimination of defective cells and more recently promotion of cancer. Many effective anti-cancer therapies depend on Fas-mediated apoptosis to eradicate tumor cells and ineffective Fas- apoptotic signaling is a basis for primary as well as acquired resistance to chemotherapy. We hypothesized that Fas is subjected to direct regulation and inhibition of Fas attained by cancer cells and may explain the emergence of chemoresistance. To screen for potential binding modulators of Fas, we analyzed lymphoma cells for Fas binding proteins.We first purified Fas associated proteins by using activating CH-11 antibody bound to intact BJAB cells. After immunoprecipitation, any remaining Fas, considered activation–resistant, was subjected to the second immunoprecipitation with Fas antibody B-10 followed by liquid chromatography and tandem mass spectroscopy. This purification scheme identified high scoring peptides derived from nucleolin, a nuclear protein known to be overexpressed in cancer. Nucleolin is selectively expressed on the surfaces of cancer cells and blood vessels undergoing angiogenesis. In a cell culture system, we confirmed binding of nucleolin to Fas and the presence of nucleolin-Fas complexes on the surface of lymphoma cells by surface biotin labeling. Using deletion mutants of nucleolin, we identified RNA binding domain 4 and glycine/arginine rich region to be required for the binding to Fas. BJAB cells with partially knockdown (KD) nucleolin showed significantly higher rates of apoptosis in response to stimulation with CH-11 and FasL when compared to nontarget KD controls. Importantly, the lower levels of nucleolin in knockdown cells did not affect total and surface Fas expression. Nucleolin present on the cell surface prevented binding of FasL and CH-11 to the receptor and thus provides a mechanism for blocking activation of Fas apoptosis. To examine the role of nucleon in vivo, we transfected mice with nucleolin-expressing plasmids using the hydrodynamic transfection method. The mice overexpressing nucleolin showed significantly higher survival rates than vector control transfected mice (P=.01) after a challenge with a lethal dose of agonistic anti-Fas antibody.We next examined the expression of nucleolin in human lymphomas. Cell lines derived from lymphomas of different histological types consistently expressed nucleolin protein. We found nucleolin expressed on the surface of cells in over 20 primary lymphoma isolates, whereas peripheral blood lymphocytes showed low or undetectable levels. Lymphoma tissue microarray staining showed a correlation between nucleolin and Ki-67 expression. Whether nucleolin expression also correlates with adverse clinical features in lymphoma is currently under evaluation.Taken together, we show here that the known cancer associated protein nucleolin is overexpressed on surface of lymphoma cells where it binds to Fas receptor and blocks Fas signaling and apoptosis. We expect that further analysis of nucleolin properties will reveal how Fas-nucleolin interaction can be targeted to enhance killing of cancer cells leading eventually to cell surface nucleolin targeting therapy. Disclosures:Fayad:Roche: Research Funding.

Nucleolin mediates the antiangiogenesis effect of the pseudopeptide N6L

BackgroundNucleolin is a protein over-expressed on the surface of activated cells. Recent studies have underlined the involvement of cell surface nucleolin in angiogenesis processes. This cell surface molecule serves as a receptor for various ligands implicated in pathophysiological processes such as growth factors, cell adhesion molecules like integrins, selectins or laminin-1, lipoproteins and viruses. N6L is a synthetic multimeric pseudopeptide that binds cell surface expressed nucleolin and inhibits cell proliferation.ResultsIn the present work, we further investigated the mechanisms of action of pseudopeptide N6L on angiogenesis using HUVECs. We provide evidence that N6L inhibits the in vitro adhesion, proliferation and migration of HUVECs without inducing their apoptosis. In addition, we found that N6L downregulates MMP-2 in HUVECs. The above biological actions are regulated by SRC, ERK1/2, AKT and FAK kinases as we found that N6L inhibits their activation in HUVECs. Finally, down regulation of nucleolin using siRNA demonstrated the implication of nucleolin in the biological actions of these peptides.ConclusionsTaken together, these results indicate that N6L could constitute an interesting therapeutic tool for treating diseases associated with excessive angiogenesis.

Heat Shock Cognate 70 Regulates the Translocation and Angiogenic Function of Nucleolin

Cell surface nucleolin (NCL) plays fundamental roles in tumor angiogenesis. However, the mechanism underlying its surface translocation remains obscure. The present study discovered that heat shock cognate 70 (Hsc70) is essential in both the surface translocation and the angiogenic function of NCL. We identified that Hsc70 interacted with NCL in endothelial cells via the peptide-binding domain of Hsc70 and the RNA-binding domain of NCL. Functional knockdown of Hsc70 remarkably inhibited the expression of surface NCL, which was rescued by wild-type Hsc70 rather than its truncations. Phosphorylation of NCL by either protein kinase C-ξ or casein kinase 2 mediated its interaction with Hsc70 and the surface expression. Hsc70 regulated NCL translocation via stabilizing NCL and enhancing its interaction with nonmuscle myosin heavy chain 9. Moreover, Hsc70 was associated with NCL-induced endothelial cell migration and tubule formation in vitro and angiogenesis in both matrigel plugs and xenograft tumors. Tissue array analysis revealed that the expression levels of NCL and Hsc70 were intimately correlated in human lung adenocarcinomas. Our study demonstrates that Hsc70 is a prerequisite for the surface translocation and angiogenic function of NCL, which suggests strategies to target both Hsc70 and NCL for more effective antiangiogenic therapies.

Abstract 4623: Human anti-nucleolin antibodies with broad spectrum anticancer activity

Abstract Extensive preclinical studies have validated nucleolin as a new therapeutic target in oncology. Confocal microscopy, immunohistochemistry, and cell fractionation studies have shown that this protein is highly overexpressed in the plasma membrane and cytoplasm of a wide variety of human hematological and solid tumor cells, but is usually undetectable on the cell surface or in the cytoplasm of the corresponding normal cells. We have utilized our licensed platform technology to generate a first-in-class panel of eight fully human monoclonal IgG1 antibodies (HuMAbs). These antibodies bind specifically to nucleolin on the tumor cell surface, which in turn elicits potent cytotoxicity to a variety of human tumor cell lines. One such example is CP101, which killed MV4-11 (AML), MCF-7 (breast), DU145 (prostate), PANC-1 and MIA PaCa-2 (pancreas) tumor cell lines with IC50 values ranging from (0.5-2.0 µg/ml; 3-12 nM) following exposure to the HuMAb for 96 hrs. These in vitro assays were performed in the absence of human complement and immune effector cells required for complement-dependent cellular cytotoxicity (CDCC) and antibody-dependent cellular cytotoxicity (ADCC), respectively. These results are consistent with published observations that anti-nucleolin HuMAbs can exploit the known shuttling function of cell surface nucleolin to gain intracellular access and induce direct tumor cytotoxicity. In contrast to its cytocidal effects on tumor cells, CP101 had no effect on the viability of either MCF-10A normal human breast epithelial cells or normal human CD19+ B cells, neither of which expresses nucleolin on the cell surface. In summary, the results suggest that anti-nucleolin HuMAbs are unique in that they can exert broad spectrum antitumor activity independently of the immune mechanism of CDCC and ADCC, while having no detectable effects on the viability of the corresponding normal cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4623. doi:1538-7445.AM2012-4623

Abstract 561: Role of nucleolin in activation of NF-κB signaling with Tip≤, a carcinogenic factor of H. pylori

Abstract TNF-α inducing protein (Tip≤), a carcinogenic factor secreted from H. pylori, enters the cell through binding to nucleolin, a receptor of Tip≤ on the cell surface. Internalized Tip≤ induces NF-κB activation and TNF-α gene expression and finally induces tumor promotion in the stomach. Nucleolin is a major protein in nucleoli, but significant amounts of nucleolin localize on the cell surface of several gastric cancer cell lines. We investigate the relationship between induction of both NF-κB activation and TNF-α gene expression and the presence of nucleolin, the latter of which acts as a shuttling protein of various molecules, such as Tip≤, lactoferrin and AS1411, from cell surface to cytosol or nuclei. Lactoferrin, iron-binding glycoprotein with 80 kDa, shows anti-cancer activity and preventive activity of H. pylori infection. AS1411 is a nucleolin targeted DNA aptamer associated with a potent anti-cancer activity. First, we studied the effects of lactoferrin, AS1411, and anti-NUC295 (an antibody recognizing cell surface nucleolin) on Tip≤ incorporation into the cells and Tip≤-induced TNF-α gene expression. Pretreatment of mouse gastric cancer cells (MGT-40) with lactoferrin significantly inhibited the incorporation of Tip≤ and Tip≤-induced TNF-α gene expression. However, pretreatment with AS1411 enhanced the incorporation of Tip≤, and inhibited Tip≤-induced TNF-α gene expression. It is of interest to note that Anti-NUC295 enhanced both the incorporation of Tip≤ and Tip≤-induced TNF-α gene expression. These results suggest that both lactoferrin and AS1411 inhibit tumor promoting activity of Tip≤ mediated through inhibition of NF-κB signaling. Thus we think that nucleolin acts as not only a shuttling protein but also a direct regulator of NF-κB signaling. We discuss how lactoferrin and AS1411 inhibit NF-κB activation induced by Tip≤-nucleolin complex, and how nucleolin regulates the NF-κB signaling pathway. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 561. doi:1538-7445.AM2012-561

Human gastric cancer development with TNF-α-inducing protein secreted from Helicobacter pylori

TNF-α-inducing protein (Tipα) is a unique carcinogenic factor of Helicobacter pylori, which is secreted into culture broth. The biological activities of Tipα and deletion mutant were studied. Tipα protein specifically binds to cell-surface nucleolin and then enters the gastric cancer cells, where TNF-α and chemokine gene expressions are induced by NF-κB activation. Nucleolin localizes on the surface of gastric cancer cells, and interaction between Tipα and cell-surface nucleolin causes a cancer-oriented microenvironment that increases the risk of gastric cancer. This paper discusses a new mechanism of gastric cancer development with H. pylori and provides a new preventive strategy.