The autophagy protein Ambra1 regulates gene expression by supporting novel transcriptional complexes

Ambra1 is considered an autophagy and trafficking protein with roles in neurogenesis and cancer cell invasion. Here, we report that Ambra1 also localizes to the nucleus of cancer cells, where it has a novel nuclear scaffolding function that controls gene expression. Using biochemical fractionation and proteomics, we found that Ambra1 binds to multiple classes of proteins in the nucleus, including nuclear pore proteins, adaptor proteins such as FAK and Akap8, chromatin-modifying proteins, and transcriptional regulators like Brg1 and Atf2. We identified biologically important genes, such as Angpt1, Tgfb2, Tgfb3, Itga8, and Itgb7, whose transcription is regulated by Ambra1-scaffolded complexes, likely by altering histone modifications and Atf2 activity. Therefore, in addition to its recognized roles in autophagy and trafficking, Ambra1 scaffolds protein complexes at chromatin, regulating transcriptional signaling in the nucleus. This novel function for Ambra1, and the specific genes impacted, may help to explain the wider role of Ambra1 in cancer cell biology.

Stem cell enriched lipotransfer reverses the effects of fibrosis in systemic sclerosis

Oro-facial fibrosis in systemic sclerosis (Scleroderma;SSc) has a major impact on mouth function, facial appearance, and patient quality of life. Lipotransfer is a method of reconstruction that can be used in the treatment of oro-facial fibrosis. The effect of this treatment not only restores oro-facial volume but has also been found to reverse the effects of oro-facial fibrosis. Adipose derived stem cells (ADSCs) within the engrafted adipose tissue have been shown to be anti-fibrotic in SSc and are proposed as the mechanism of the anti-fibrotic effect of lipotransfer. A cohort of 62 SSc patients with oro-facial fibrosis were assessed before and after stem cell enriched lipotransfer treatment. Clinical evaluation included assessment of mouth function using a validated assessment tool (Mouth Handicap in Systemic Sclerosis Scale-MHISS), validated psychological measurements and pre and post-operative volumetric assessment. In addition, to understand the mechanism by which the anti-fibrotic effect of ADSCs occur, SSc derived fibroblasts and ADSCs from this cohort of patients were co-cultured in direct and indirect culture systems and compared to monoculture controls. Cell viability, DNA content, protein secretion of known fibrotic mediators including growth factor- β1 (TGF β-1) and connective tissue growth factor (CTGF) using ELISA analysis and fibrosis gene expression using a fibrosis pathway specific qPCR array were evaluated. Mouth function (MHISS) was significantly improved (6.85±5.07) (p<0.0001) after treatment. All psychological measures were significantly improved: DAS 24 (12.1±9.5) (p<0.0001); HADS-anxiety (2.8±3.2) (p<0.0001), HADS-depression (2.0±3.1) (p<0.0001); BFNE (2.9 ± 4.3) (p<0.0001); VAS (3.56±4.1) (p<0.0001). Multiple treatments further improved mouth function (p<0.05), DAS (p<0.0001) and VAS (p = 0.01) scores. SSc fibroblast viability and proliferation was significantly reduced in co-culture compared to monoculture via a paracrine effect over 14 days (p < 0.0001). Protein secretion of transforming growth factor (TGF-β1) and connective tissue growth factor (CTGF) was significantly reduced in co-culture compared to monoculture (p < 0.0001). Multiple fibrosis associated genes were down regulated in SSc co-culture compared to monoculture after 14 days including Matrix metalloproteinase-8 (MMMP-8), Platelet derived growth factor-β (PDGF-β) and Integrin Subunit Beta 6 (ITG-β6). Autologous stem cell enriched lipotransfer significantly improved the effects of oro-facial fibrosis in SSc in this open cohort study. Lipotransfer may reduce dermal fibrosis through the suppression of fibroblast proliferation and key regulators of fibrogenesis including TG-β1 and CTGF. Our findings warrant further investigation in a randomised controlled trial.

Cisplatin at sub-toxic levels mediates integrin switch in lung cancer cells

BACKGROUND

Resistance to chemotherapeutic agents, as well as enhanced metastasis, have been frequently reported in lung cancer.

MATERIALS AND METHODS

Cytotoxicity and proliferative effects of cisplatin on H460 lung cancer cells were evaluated by the MTT assay. Migration capacity was evaluated by the wound healing assay. The number of filopodia per cell were detected by rhodamine-phalloidin staining assay. The changes of protein levels of integrins, and migration-related proteins in response to cisplatin at sub-toxic concentrations were determined by western blotting.

RESULTS

Herein we demonstrate for the first time that exposure to low concentrations of cisplatin results in increase of cell motility with the alteration of integrin expression. Cisplatin-treated cells exhibited a significant increase in the number of filopodia per cell in correlation with enhanced migration. Migration regulatory proteins, namely activated forms of focal-adhesion kinase (FAK) and ATP-dependent tyrosine kinase (AKT), were found to significantly be up-regulated in cisplatin-treated cells in comparison to those of the non-treated control. Active Rho A-GTP and Rac-GTP were found to be increased in accordance with activation of FAK/AKT signals. Furthermore, we found that such migration enhancement may be in part due to the integrin switch mediated by cisplatin treatment. Cisplatin induced a dramatic alteration in the integrin expression pattern by up-regulating integrin α4, αv, β1, and β5 which were previously reported to increase cell motility, while it had no effect on integrin α5, and β3.

CONCLUSION

As the integrin switch is a hallmark of highly aggressive cancer, these findings may provide insights for better understanding of cancer cell adaptation after exposure to cisplatin.

Differential spheroid formation by oral cancer cells

Squamous cell carcinomas (SCC) make up 96% of all oral cancers. Most laboratory SCC studies grow cells as a monolayer, which does not accurately represent the disease in vivo. We used a more relevant multicellular spheroid (MCS) model to study this disease. The SCC9β6KDFyn cell line, which expresses full-length β6 and a kinase dead Fyn formed the largest MCS. Cell adhesive properties are dynamic and N-cadherin was increased in the largest MCS. c-Raf mediates the survival of tumor cells and was consistently expressed both in monolayers and in the MCS by SCC9β6D1 cells which lack the β6 cytoplasmic tail and, do not activate Fyn. SCC9β6KDFyn cells also express high levels of c-Raf when grown as spheroids in which Fyn suppression stimulates MCS formation. Tumor microenvironment and growth patterns modulate cell behavior and suppression of Fyn kinase may promote MCS growth.

Interaction between 24-hydroxycholesterol, oxidative stress, and amyloid-β in amplifying neuronal damage in Alzheimer's disease: three partners in crime

All three cholesterol oxidation products implicated thus far in the pathogenesis of Alzheimer's disease, 7β-hydroxycholesterol, 24-hydroxycholesterol, and 27-hydroxycholesterol, markedly enhance the binding of amyloid-beta (Aβ) to human differentiated neuronal cell lines (SK-N-BE and NT-2) by up-regulating net expression and synthesis of CD36 and β1-integrin receptors. However, only 24-hydroxycholesterol markedly potentiates the pro-apoptotic and pro-necrogenic effects of Aβ(1-42) peptide on these cells: 7β-hydroxycholesterol and 27-hydroxycholesterol, like unoxidized cholesterol, show no potentiating effect. This peculiar behavior of 24-hydroxycholesterol at physiologic concentrations (1 μm) depends on its strong enhancement of the intracellular generation of NADPH oxidase-dependent reactive oxygen species (ROS), mainly H(2) O(2) , and the consequent impairment of neuronal cell redox equilibrium, measured in terms of the GSSG/GSH ratio. Cell incubation with antioxidants quercetin or genistein prevents 24-hydroxycholesterol's pro-oxidant effect and potentiation of Aβ-induced necrosis and apoptosis. Thus, the presence of 24-hydroxycholesterol in the close vicinity of amyloid plaques appears to enhance the adhesion of large amounts of Aβ to the plasma membrane of neurons and then to amplify the neurotoxic action of Aβ by locally increasing ROS steady-state levels. This report further supports a primary involvement of altered brain cholesterol metabolism in the complex pathogenesis of Alzheimer's disease.

Tiger shrimp (Penaeus monodon) penaeidin possesses cytokine features to promote integrin-mediated granulocyte and semi-granulocyte adhesion

Recent studies indicated that antimicrobial peptides (AMPs) play multiple roles in both innate and adaptive immune functions. The penaeidin of tiger shrimp Penaeus monodon shows an antimicrobial activity against Gram-positive bacteria and filamentous fungi. To study immunomodulation functions of the penaeidin, we transfected shrimp hemocytes in primary culture with penaeidin-specific small interfering RNA (siRNA-3) and observed a concomitant 20% reduction in adhesive hemocytes compared with mock-transfected cells. The addition of biosynthesized or chemically synthesized penaeidin or penaeidin proline-rich domain (PRD) to the culture medium of penaeidin knock-down hemocytes led to a full recovery in the number of adhesive hemocytes. The effect of penaeidin knock-down on the expression of tiger shrimp cell adhesion-associated molecules was examined using real-time Q-PCR. Results demonstrated 91% and 64% decreases in the expression of integrin-beta and collagen, respectively, and a 396% increase in the expression of collagenase. The addition of chemically synthesized penaeidin after penaeidin knock-down hemocytes normalized the expression of these genes. The addition of the integrin-beta ligand competitor RGDS to mock-transfected hemocytes decreased the number of adhesive hemocytes similar to penaeidin knock-down. In conclusion, penaeidin possesses an integrin-beta-mediated cytokine feature that promotes shrimp granulocyte and semi-granulocyte adhesion. This is the first report about functional shrimp cytokine.

A beta integrin subunit regulates bacterial phagocytosis in medfly haemocytes

We have recently reported that the activation of focal adhesion kinase (FAK) and its downstream targets upon pathogen challenge regulate phagocytosis in medfly haemocytes. The goal of this study was to further explore the signalling pathway underlying the process of phagocytosis. In particular, in this report, we used flow cytometry, RNA interference, enzyme-linked immunosorbent assay, Western blot and immunoprecipitation analysis to demonstrate the haemocyte surface receptor, through which the extracellular signals in response to bacteria are transmitted intracellularly. The presented data demonstrate the expression of a beta integrin subunit in the surface of medfly haemocytes that transmits signals upon pathogen triggering to FAK and its downstream targets, Src, MAP kinases and Elk-1-like protein, for the engulfment of pathogen. Interestingly LPS is not internalized through integrins.

[Study on the overlapping growth of hepatoma cells in vitro]

This study inquired into the formation of the "overlapping growth" of hepatoma cells through quantitative characterization on the growth of hepatoma cells in situ by means of morphological observation, Image Tool computer analytic system, statistical analysis as well as the experimental methods of cell mechanics and biochemistry. The results were as follows: (1) The ability of hepatoma cells to regulate cell morphological deformation was better than that of hepatic cells; (2) While we were using micropipette aspiration technique to suck the "overlapping growth plaque" of hepatoma cells, the "overlapping growth plaque" fell off from the substrate, leaving a blank area; (3) Integrin expression of hepatoma cells was more obvious than that of hepatic cells; (4) Fibronectin (Fn) down-regulated the integrin expression in the hepatoma cells cultured on the Fn coated surface, enhanced the cells' adhesion ability and morphological stability, but reduced the formation and aggregation of the round cells. These results indicated (1) The so-called overlapping growing area was actually formed by many closely arrayed and piled round cells; (2) The production of round cells may be caused by integrin abnormal expression and the effect on the hepatoma cells adhesion stability; (3) The formation of "overlapping growth plaque" in hepatoma cells is related to the round cells' congregation induced by the high frequency morphological transformation.

Analysis of basement membrane structure and inflammation during the development of esophageal squamous cell carcinoma in the Chinese Chaoshan high risk region

BACKGROUND & AIMS

To investigate relationships between basement membrane structure, inflammation, beta1 integrin expression, activation of ERK/MAPK signaling pathways, and cell proliferation in esophageal mucosa at various stages during the evolution of esophageal squamous cell carcinoma.

METHODS

Three tissue arrays were made of 228 tissue cores from 428 surgically-resected specimens. The arrays included 26 samples of normal epithelium, 28 with hyperplasia, 18 with dysplasia, 27 with carcinoma in situ and 129 with invasive carcinoma. In addition, 21 cases of hyperplasia, 13 cases of dysplasia and 13 case of carcinoma in situ were obtained by manual microdissection of unfixed frozen tissue. Hematoxylin and eosin stained sections were used to evaluate the epithelium and inflammation. The periodic acid-Schiff stain and an immunohistochemical stain for laminin were used to examine the structure of basement membranes. The expression of beta1 integrin, p-ERK, and Ki67 were evaluated by quantitative immunohistochemistry. RT-PCR and Western blots were also used to detect expression of beta1 integrin.

RESULTS

Quantitative scales were developed to classify basement membrane structure and inflammation. Basement membrane alterations correlated with the degree of epithelial change (chi2 = 501.9, p < 0.01) and with the degree of lymphocytic infiltration in the lamina propria and epithelium (chi2 = 273.4, p < 0.01). There was a significant relationship between the extent of basement membrane alteration and the expression of beta1 integrin, p-ERK, and Ki67.

CONCLUSIONS

The correlations suggest that there is a direct relationship between basement membrane structure and the development of esophageal squamous cell carcinoma.

Brain microenvironment promotes the final functional maturation of tumor-specific effector CD8+ T cells

During the priming phase of an antitumor immune response, CD8(+) T cells undergo a program of differentiation driven by professional APCs in secondary lymphoid organs. This leads to clonal expansion and acquisition both of effector functions and a specific adhesion molecule pattern. Whether this program can be reshaped during the effector phase to adapt to the effector site microenvironment is unknown. We investigated this in murine brain tumor models using adoptive transfer of tumor-specific CD8(+) T cells, and in spontaneous immune responses of patients with malignant glioma. Our data show proliferation of Ag-experienced tumor-specific T cells within the brain parenchyma. Moreover, CD8(+) T cells further differentiated in the brain, exhibiting enhanced IFN-gamma and granzyme B expression and induction of alpha(E)(CD103)beta(7) integrin. This unexpected integrin expression identified a subpopulation of CD8(+) T cells conditioned by the brain microenvironment and also had functional consequences: alpha(E)(CD103)beta(7)-expressing CD8(+) T cells had enhanced retention in the brain. These findings were further investigated for CD8(+) T cells infiltrating human malignant glioma; CD8(+) T cells expressed alpha(E)(CD103)beta(7) integrin and granzyme B as in the murine models. Overall, our data indicate that the effector site plays an active role in shaping the effector phase of tumor immunity. The potential for local expansion and functional reprogramming should be considered when optimizing future immunotherapies for regional tumor control.

In Vitro Induction of Mucosa-Type Dendritic Cells by All-Trans Retinoic Acid

Efficient induction of mucosal immunity usually employs nasal or oral vaccination while parenteral immunization generally is ineffective at generating mucosal immune responses. This relates to the unique ability of resident mucosal dendritic cells (DC) to induce IgA switching and to imprint mucosa-specific homing receptors on lymphocytes. Based on the well-established plasticity of the DC system, this study sought to investigate whether peripheral DC could be modulated toward "mucosa-type" DC by treatment with immunomodulatory, and therefore potentially adjuvant-like, factors. In this study, we show that monocyte-derived DCs pretreated with the vitamin A derivative all-trans retinoic acid (RA) indeed acquired several attributes characteristic of mucosal DC: secretion of TGF-beta and IL-6 and the capacity to augment mucosal homing receptor expression and IgA responses in cocultured lymphocytes. Addition of a TGF-beta-neutralizing Ab to cocultures significantly inhibited alpha4beta7 integrin, but not CCR9 mRNA expression by the lymphocytes. Both alpha4beta7 integrin and CCR9 mRNA expression, but not IgA production, were suppressed in the presence of a RA receptor antagonist. None of the observed effects on the lymphocytes were influenced by citral, a retinal dehydrogenase inhibitor, arguing against a role for de novo-synthesized RA. Collectively, our findings identified a novel role for RA as a mucosal immune modulator targeting DC. Our results further demonstrate that DC can act as efficient carriers of RA at least in vitro. Consequently, RA targeting of DC shows potential for promoting vaccine-induced mucosal immune responses via a parenteral route of immunization.

Effect of extracellular matrix on adhesion, viability, actin cytoskeleton and K+ currents of cells expressing human ether à go-go channels

Ether à go-go (EAG) potassium channels possess oncogenic properties and have gained great interest as research tools for cancer detection and therapy. Besides, EAG electrophysiological properties are regulated through the cell cycle and determined by cytoskeletal interactions. Thus, because of the pivotal role of extracellular matrix (ECM) and cytoskeleton in cancer progression, we studied the effect of ECM components on adhesion, viability, actin organization and EAG currents in wild-type CHO cells (CHO-wt) and cells expressing human EAG channels (CHO-hEAG). At short incubation times, adhesion and viability of CHO-hEAG cells grown on collagen, heparin or poly-lysine were lower than CHO-wt cells, however, only CHO-hEAG sustained growing under total serum starvation. CHO-hEAG cells grown on poly-lysine did not organize their cytoskeleton but when grown on collagen or fibronectin displayed lamellipodia and stress fibers, respectively. Interestingly, EAG expressing cells displayed special actin structures suggesting a dynamic actin cytoskeleton, such structures were not exhibited by wild-type cells. EAG current density was significantly lower in cells grown on collagen at short incubation times. Finally, we studied potential associations between hEAG channels and integrins or actin filaments by confocal microscopy. No association between beta1-integrins and hEAG channels was found, however, a very strong co-localization was observed between hEAG channels and actin filaments, supported by immunoblot experiments in which hEAG channels were found in the insoluble fraction (associated to cytoskeleton). Our results suggest ECM components as potential modulators of oncogenic human-EAG expressing cells and emphasize the relationship between potassium channels, cytoskeleton, ECM and cancer.

2,3,7,8-Tetrachlorodibenzo-p-dioxin induces premature activation of the KLF2 regulon during thymocyte development

The environmental pollutant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) causes numerous and diverse toxic events via activation of the aryl hydrocarbon receptor, including atrophy of the thymus. Exposure to TCDD induces acute thymocyte cell loss, which occurs concomitantly with proliferation arrest and premature emigration of triple negative (TN; CD4(-), CD8(-), CD3(-)) T cell progenitors. In this report, we demonstrate that TCDD exposure results in dysregulation of KLF2 (Kruppel-like factor 2) expression in developing thymocytes. The Klf2 gene encodes an Sp1-like zinc finger transcription factor that functions as a central regulator of T lymphocyte proliferation and trafficking. During normal thymocyte development, KLF2 is expressed exclusively in CD4 and CD8 single positive T cells and promotes a nonproliferative, promigratory phenotype. In mice exposed to TCDD, however, the Klf2 gene is prematurely expressed in TN thymocytes. Administration of a 100 microg/kg dose of TCDD results in a approximately 15-fold induction of KLF2 as early as the TN2 (CD44(+), CD25(+)) stage of development and immediately precedes acute cell loss in the TN3, TN4, and double positive (CD4(+), CD8(+)) cell stages. Induction of KLF2 occurs within 12 h of TCDD exposure and is fully dependent on expression of the aryl hydrocarbon receptor. In addition, TCDD exposure alters the expression of several factors comprising the KLF2 regulon, including Edg1/S1P(1), beta(7) integrin, CD52, Cdkn2d (cyclin-dependent kinase inhibitor 2D), s100a4, and IL10R alpha. These findings indicate that the pollutant TCDD interferes with early thymopoeisis via ectopic expression of the KLF2 regulon.

Low percentages of circulating CD8(+)/CD45RA(+) human T lymphocytes expressing beta7 integrin correlate with the occurrence of intestinal acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

OBJECTIVE

Effector phase of acute graft-versus-host disease (a-GVHD) is mainly mediated by donor-derived, anti-host cytotoxic T cells. T-cell homing into gut-associated lymphoid tissues is ascribed to the alpha4beta7 integrin. We reasoned that development of intestinal a-GVHD might be triggered by recruitment in the intestinal mucosa of circulating, alloreactive, alpha4beta7(+) donor T cells. Therefore, we evaluated the correlation existing between circulating beta7(+) T-lymphocyte subsets early after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and occurrence of a-GVHD.

PATIENTS AND METHODS

Surface expression of beta7 integrin on T cells was evaluated by means of direct immunofluorescence, in three-color analysis. Sixty-five patients given allo-HSCT were evaluated: 13 of them experienced intestinal a-GVHD, 14 developed a-GVHD without intestinal involvement, and 38 did not develop a-GVHD. Patients were studied early after initial signs of hematologic reconstitution and before occurrence of a-GVHD.

RESULTS

We found a significantly higher absolute number of CD8(+) and a significantly lower percentage of CD8(+)CD45RA(+)beta7(+) T cells in patients with intestinal a-GVHD than in patients with a-GVHD without intestinal involvement (p = 0.003 and p = 0.003, respectively) or not experiencing a-GVHD (p = 0.02 and p = 0.002, respectively). In particular, we found that intestinal a-GVHD occurred in over 70% of patients showing an absolute number of CD8(+) T cells > or = 60 x 10(6)/L and a percentage of circulating CD8(+)CD45RA(+)beta7(+) T cells < 35%.

CONCLUSION

Measuring the absolute number of CD8(+) T cells and percentage of CD8(+)CD45RA(+)beta7(+) T cells at time of hematologic reconstitution may help identify patients at risk of developing intestinal a-GVHD who could benefit from strategies aimed at hampering alloreactive T-cell homing to intestinal mucosa.

Extracellular matrix-mediated tissue remodeling following axial movement of teeth

Tooth eruption is a multifactorial process involving movement of existing tissues and formation of new tissues coordinated by a complex set of genetic events. We have used the model of the unopposed rodent molar to study morphological and genetic mechanisms involved in axial movement of teeth. Following extraction of opposing upper molars, lower molars supererupted by 0.13 mm. Labeled tissue sections revealed significant amounts of new bone and cementum apposition at the root apex of the unopposed side following supereruption for 12 days. Newly apposited cementum and alveolar bone layers were approximately 3-fold thicker in the experimental vs the control group, whereas periodontal ligament width was maintained. Tartrate-resistant acid phosphatase staining indicated bone resorption at the mesial alveolar walls of unopposed molars and provided in tandem with new bone formation at the distal alveolar walls an explanation for the distal drift of molars in this model. Microarray analysis and semiquantitative RT-PCR demonstrated a significant increase in collagen I, integrin beta5, and SPARC gene expression as revealed by comparison between the unopposed molar group and the control group. Immunohistochemical verification revealed increased levels of integrin beta5 and SPARC labeling in the periodontal ligament of the unopposed molar. Together our findings suggest that posteruptive axial movement of teeth was accomplished by significant formation of new root cementum and alveolar bone at the root apex in tandem with upregulation of collagen I, integrin beta5, and SPARC gene expression.

Telomerase flies the coop: the telomerase RNA component as a viral-encoded oncogene

Telomerase, the enzyme that elongates our telomeres, is crucial for cancer development based on extensive analyses of human cells, human cancers, and mouse models. New data now suggest that a viral telomerase RNA gene encoded by Marek's disease virus (MDV), an oncogenic herpesvirus of chickens, promotes tumor formation. These findings highlight the importance of telomerase in cancer and raise new questions regarding the mechanisms by which the telomerase RNA component supports tumorigenesis.

A virus-encoded telomerase RNA promotes malignant T cell lymphomagenesis

Telomerase is a ribonucleoprotein complex consisting of two essential core components: a reverse transcriptase and an RNA subunit (telomerase RNA [TR]). Dysregulation of telomerase has been associated with cell immortalization and oncogenesis. Marek's disease herpesvirus (MDV) induces a malignant T cell lymphoma in chickens and harbors in its genome two identical copies of a viral TR (vTR) with 88% sequence identity to chicken TR. MDV mutants lacking both copies of vTR were significantly impaired in their ability to induce T cell lymphomas, although lytic replication in vivo was unaffected. Tumor incidences were reduced by >60% in chickens infected with vTR⁻ viruses compared with animals inoculated with MDV harboring at least one intact copy of vTR. Lymphomas in animals infected with the vTR⁻ viruses were also significantly smaller in size and less disseminated. Constitutive expression of vTR in the chicken fibroblast cell line DF-1 resulted in a phenotype consistent with transformation as indicated by morphological alteration, enhanced anchorage-independent cell growth, cell growth beyond saturation density, and increased expression levels of integrin αv. We concluded that vTR plays a critical role in MDV-induced T cell lymphomagenesis. Furthermore, our results provide the first description of tumor-promoting effects of TR in a natural virus–host infection model.

The inhibition of tumor cell adhesion on human mesothelial cells (HOMC) by phospholipids in vitro

BACKGROUND AND AIMS

Intraperitoneal tumor cell adhesion to extracellular matrix and to mesothelial cells mediated by integrins is an important step in developing peritoneal carcinosis. In former animal studies, we could demonstrate that intraperitoneal treatment with a new phospholipid (PL) emulsion significantly reduces the amount of peritoneal carcinosis by adhesion prevention. This in vitro study tries to elucidate the influence of phospholipids on cells of the human gastric cancer cell line (NUGC-4) and the human rectal cancer cell line (HRT-18) adhering to mesothelial cells (HOMC) in a monolayer culture in vitro.

MATERIALS AND METHODS

HOMC cells were derived from omentum majus from patients undergoing elective abdominal surgery. Three passages of both cancer cell lines (NUGC-4 and HRT-18) were used. 1x10(5)/100 microl (HRT-18) or 1.2x10(5)/100 microl (NUGC-4) cells, according to forgoing dilution series, were pretreated with different concentrations of phospholipid emulsion (0.05, 0.1, 0.5, 0.75, 1% PL) stained with cell tracker chloromethyl-benzamidodialkylcarbocyanine (CM-DIL) and seeded into each well on the mesothelial monolayer. After 90 min, the number of adherent cells was counted by fluorescence microscopy at 530 and 620 nm. Additionally, flow cytometric analysis of integrin alpha3 and beta1 expression on the tumor cell surface after treatment with phospholipids was completed.

RESULTS

We found a dose dependent effect of phospholipids on both tumor cell lines causing a reduction of cell-cell adhesion. Already low concentrations of phospholipids (PL 0.5) had a significant influence. The mean cell count could be reduced from 234+/-12/mm2 in controls to 124+/-41/mm2 (PL 0.5; NUG-4) and from 295+/-49/mm2 to 169+/-29/mm2 (PL 0.5; HRT-18), respectively. Additionally, the integrin alpha3 and beta1 expression on both cell lines could be reduced.

CONCLUSION

Our results within the scope of published data indicate that adhesion prevention is capable to reduce peritoneal carcinosis.

Overexpression of c-Maf Contributes to T-Cell Lymphoma in Both Mice and Human

c-Maf translocation or overexpression has been observed in human multiple myeloma. Although c-maf might function as an oncogene in multiple myeloma, a role for this gene in other cancers has not been shown. In this study, we have found that mice transgenic for c-Maf whose expression was direct to the T-cell compartment developed T-cell lymphoma. Moreover, we showed that cyclin D2, integrin beta(7), and ARK5 were up-regulated in c-Maf transgenic lymphoma cells. Furthermore, 60% of human T-cell lymphomas (11 of 18 cases), classified as angioimmunoblastic T-cell lymphoma, were found to express c-Maf. These results suggest that c-Maf might cause a type of T-cell lymphoma in both mice and humans and that ARK5, in addition to cyclin D2 and integrin beta(7), might be downstream target genes of c-Maf leading to malignant transformation.

Characterizing the circulating, gliadin-specific CD4+ memory T cells in patients with celiac disease: linkage between memory function, gut homing and Th1 polarization

Celiac disease (CD) is a chronic, immune-mediated disorder of the gut, driven by T cells reacting locally to a distinct antigen, gliadin. Thus, CD offers the opportunity to study the T cell memory response to gliadin and whether gut tropism and T helper cell type 1 (Th1) polarization, which characterize the effector phase, are preserved in the memory progeny. It is notable that previous studies yielded conflicting results as to the presence of gliadin-specific memory CD4+ T cells in the peripheral blood of CD patients. However, we used a different and highly sensitive approach based on fluorescein-derived label dilution, whereby the memory cells are identified operationally by their greater capacity to proliferate upon re-encounter with antigen. Thus, using flow cytometry, we could resolve multiple successive generations as well as immunophenotype the dividing cells. Here, we show that the peripheral blood lymphocyte of some CD patients on a gliadin-free diet, but not healthy donors, contains a detectable population of CD4+ memory T cells specific for deamidated gliadin. Moreover, these gliadin-specific memory T cells are marked by a distinctive phenotype: They express high levels of the gut-homing beta7 integrins and primarily produce interferon-gamma and tumor necrosis factor alpha. We conclude that memory for gliadin-derived antigens within the circulating CD4+ T cells is linked with gut tropism as well as Th1 polarization.

Human gingival fibroblast integrin subunit expression on titanium implant surfaces

BACKGROUND

Implant surface characteristics have been shown to modify cell behavior and regulate integrin expression. Integrin expression and resultant integrin-mediated cellular activity are essential components of tissue healing and homeostasis. Although both osseous and soft tissue healing around dental implants are critical to clinical success, there is limited information available on the effect of implant surfaces on integrin expression in soft tissues. Therefore, the aim of this study was to examine integrin expression for gingival fibroblasts on titanium surfaces and the influence of titanium surface roughness on integrin expression and cell morphology.

METHODS

Human gingival fibroblasts were cultured on smooth (polished) and rough (sand-blasted acid-etched) titanium surfaces and a cell culture plastic (control) surface. To analyze integrin expression, total RNA was isolated from experimental and control cells, and levels of integrin subunit mRNA were assessed by reverse transcription-polymerase chain reaction (RT-PCR) using primers specific for the alpha2, alpha4, alpha5, alpha(v), and beta1 integrin subunits and aldolase (internal control). PCR products were analyzed by polyacrylamide gel electrophoresis (PAGE), confirmed via DNA sequencing, and quantified using computer-assisted densitometry. The expression of the integrin subunits was analyzed at the protein level using flow cytometry, as well as fluorescence and confocal laser microscopy. Cell morphology was evaluated using scanning electron microscopy (SEM).

RESULTS

Our experiments demonstrated cellular expression of the alpha2, alpha4, alpha5, alpha(v), and beta1 integrin subunits at both mRNA and protein levels on all surfaces. In addition, the alpha4 and beta1 mRNA levels were significantly increased on smooth titanium relative to plastic surfaces (P <.05) with intermediate mRNA levels found on the rough titanium surfaces. The smooth titanium surfaces exhibited a flat monolayer of cells, while rough titanium surfaces showed cells orienting themselves along surface irregularities.

CONCLUSIONS

These results demonstrate the presence of multiple integrin subunits in human gingival fibroblasts grown in contact with titanium implant surfaces and that titanium surface roughness alters cellular morphology but appears to have limited effects on integrin expression. This study provides insight into the complicated cellular and molecular events occurring at the implant surface that may be critical to optimizing the soft tissue interactions with the soft tissue-implant interface.

RANTES and Eotaxin Enhance CD11b and CD18 Expression on Eosinophils from Allergic Patients with Eosinophilia in the Application of Whole Blood Flow Cytometry Analysis

BACKGROUND

C-C chemokines and adhesion molecules expressed on eosinophils play an important role in the pathology of allergic inflammatory disease. C-C chemokines such as eotaxin or RANTES are involved in beta(2) integrin expression on purified eosinophils; so far we have no data on unpurified eosinophils in the peripheral blood. We measured beta(1) and beta(2) integrin activation after stimulation with eotaxin or RANTES in vitro using whole-blood flow-cytometric analysis.

METHODS

Heparinized whole blood obtained from allergic patients with eosinophilia or normal subjects was diluted with the same volume of RPMI 1640, and then cells were incubated in the presence or absence of PMA/ionomycin or chemokines for 45 min at 37 degrees C. After hemolyzation with lysing solution, expression of CD11b, CD11a, CD18 and CD49d on eosinophils was measured using flow cytometry.

RESULTS

The expression of CD11b, CD11a and CD18 in allergic patients was significantly higher than that in normal subjects. CD11b and CD18 expression showed a significant increase after stimulation with C-C chemokines, which was remarkable in allergic patients.

CONCLUSION

Eosinophils in the blood of allergic patients exhibited a higher expression of beta(2) integrins and were more sensitive to RANTES and eotaxin than those of normal subjects.

The expression of integrin alpha(v)beta6 promotes the epithelial cell morphology and suppresses invasive behavior in transformed oral keratinocytes

The expression of the integrin alpha(v)beta6 has been correlated with oral SCC invasion. We evaluated its expression in three 4NQO transformed murine oral keratinocyte cell lines (B7E3, B7E11 and B4B8). The B7E3 cells were negative for beta6, whereas the B7E11 and the B4B8 cells were both positive. The beta6 negative B7E3 cells were fibroblast-like in appearance, whereas the B7E11 cells were more epithelial-like. The B4B8 cells were a mixture of the two cell types. Using immunofluorescent microscopy, we found that vimentin was highly expressed in the B7E3 cells, whereas the B7E11 cells keratin positive. The B4B8 cells expressed both filaments. The B7E3 cells formed large tumors when injected into nude mice, whereas the B4B8 cells formed small tumors and the B7E11 cells formed none. These results suggest that the expression of the alpha(v)beta6 integrin suppresses tumor formation and may promote the epithelial phenotype in 4NQO-transformed murine oral keratinocytes.

Transcriptional activation of integrin beta6 during the epithelial-mesenchymal transition defines a novel prognostic indicator of aggressive colon carcinoma

We used a spheroid model of colon carcinoma to analyze integrin dynamics as a function of the epithelial-mesenchymal transition (EMT), a process that provides a paradigm for understanding how carcinoma cells acquire a more aggressive phenotype. This EMT involves transcriptional activation of the beta6 integrin subunit and a consequent induction of alphavbeta6 expression. This integrin enhances the tumorigenic properties of colon carcinoma, including activation of autocrine TGF-beta and migration on interstitial fibronectin. Importantly, this study validates the clinical relevance of the EMT. Kaplan-Meier analysis of beta6 expression in 488 colorectal carcinomas revealed a striking reduction in median survival time of patients with high beta6 expression. Elevated receptor expression did not simply reflect increasing tumor stage, since log-rank analysis showed a more significant impact on the survival of patients with early-stage, as opposed to late-stage, disease. Cox regression analysis confirmed that this integrin is an independent variable for these tumors. These findings define the alphavbeta6 integrin as an important risk factor for early-stage disease and a novel therapeutic candidate for colorectal cancer.

Immunohistochemical screening for beta6-integrin subunit expression in adenocarcinomas using a novel monoclonal antibody reveals strong up-regulation in pancreatic ductal adenocarcinomas in vivo and in vitro

AIMS

To analyse the expression of alphavbeta6, an epithelial integrin involved in wound healing and tumorigenesis, in various human carcinoma types.

METHODS AND RESULTS

A new monoclonal antibody to the human beta6 subunit, 5C4, was used to locate alphavbeta6 in 157 cancers of gastroenteropancreatic and 21 of lung origin. The data were validated by analysis of alphavbeta6 extracted from histological sections. Alphavbeta6 integrin showed strongest expression in 34 pancreatic ductal adenocarcinomas (mean score 2.88 +/- 0.52), followed by 24 intestinal-type gastric carcinomas (1.45 +/- 1.06) and eight lung adenocarcinomas (1.37 +/- 1.1). Moderate expression was found in 31 diffuse-type gastric carcinomas (0.94 +/- 0.83), seven duodenal adenocarcinomas (0.8 +/- 1.34) and 26 colorectal adenocarcinomas (0.76 +/- 0.71). Little alphavbeta6 was seen in seven liver cell carcinomas and six neuroendocrine tumours. Well-differentiated carcinomas expressed more beta6 than poorly differentiated tumours. Peritumoral epithelial tissues where alphavbeta6-expressing tumours arose also expressed alphavbeta6. There was no correlation between expression of alphavbeta6 and its ligands tenascin and fibronectin in pancreatic and gastric carcinomas. Spheroid formation by pancreatic carcinoma cell lines led to alphavbeta6 up-regulation, but appeared independent of classical ligand binding to alphavbeta6.

CONCLUSIONS

Our findings indicate that: (i) alphavbeta6 is overexpressed in pancreatic adenocarcinomas; (ii) alphavbeta6-positive carcinomas originate from alphavbeta6-expressing tissues; (iii) alphavbeta6 expression in tumours seems to be regulated independently from that of its ligands tenascin and fibronectin; and (iv) in-vitro overexpression of alphavbeta6 in pancreatic carcinoma cell lines accompanies spheroid formation.

[Immunohistochemical expression of integrin alphav, beta5 and beta3 in ovarian epithelial carcinoma: correlation with drug resistance of chemotherapy]

OBJECTIVE

To investigate the possible correlation between the expression of integrin alphav, beta5 and beta3 in tumor tissues and the response to chemotherapy and survival of patients with ovarian epithelial carcinoma.

METHODS

Seventy-seven patients with ovarian epithelial carcinoma from January 1996 to December 2002 were entered into the study. All subjects were matched up with the inclusion criteria and followed up till December 2003. Each patient received cytoreductive surgery and systematic chemotherapy. Patients were divided into drug resistant group (n = 26) and drug sensitive group (n = 51). The antigens of integrin alphav, beta5 and beta3 in ovarian tumour tissues were tested by immunohistochemistry. Logistic regression was employed to analyze the correlation between drug resistance and factors including patients' age, clinical stage, pathological degree and type of tumors, chemotherapy methods, operative results and the expression of integrin alphav, beta5 and beta3 in tumors. The disease prognosis was analyzed by multivariate COX regression.

RESULTS

In the drug resistance group, the expressions of integrin alphav and beta5 were significantly higher than that in the drug sensitive group (P = 0.004 and 0.001). The expression of integrin beta3 was not statistically different in the two groups (P = 0.668). According to multivariate analysis, the expression of integrin alphav and beta5 and clinical stage were three independent factors correlated with drug resistance and disease prognosis for the patients with ovarian epithelial carcinoma (P = 0.014, 0.030, 0.042 for drug resistance; and P = 0.045, 0.031, 0.001 for prognosis respectively).

CONCLUSION

The high expressions of integrin alphav and beta5 in ovarian epithelial carcinoma are risk factors for drug resistance and poor disease prognosis.

Integration and independent acquisition of specialized skin- versus gut-homing and Th1 versus Th2 cytokine synthesis phenotypes in human CD4+ T cells

CD4+)T helper cells are heterogeneous in terms of tissue-specific homing and cytokine synthesis phenotypes. The mechanisms for the acquisition of tissue-specific homing phenotypes and their relationship with the attainment of polarized cytokine synthesis profiles of T cells are critically important but poorly understood. Here, we analyze the coordinate acquisition of Th1 versus Th2 cytokine (IFN-gamma vs. IL-4) and skin- versus gut-homing (CLA vs. integrin beta7) phenotypes in human CD4+ T cells. We show that the acquisition of skin- versus gut-homing T cell phenotypes is independent of Th1 versus Th2 cell fate determination and that it occurs in relation to cell cycle progression following instructive mechanisms and distinct kinetics. Expression of chemokine receptors CXCR3 and CCR4 correlates with the acquisition of Th1 versus Th2 rather than skin- versus gut-homing phenotypes. These findings, together with the skewed overlap observed in vivo between CLA vs. integrin beta7 and IL-4 vs. IFN-gamma expression, suggest a novel interpretation to the complex patterns of chemokine receptor expression on memory T cells.

Uni-axial cyclic stretch induces Cbfa1 expression in spinal ligament cells derived from patients with ossification of the posterior longitudinal ligament

Ossification of the posterior longitudinal ligament of the spine (OPLL) is characterized by ectopic bone formation in the spinal ligaments. Mechanical stress, which acts on the posterior ligaments, is thought to be an important factor in the progression of OPLL. To clarify this mechanism, we investigated the effects of in vitro cyclic stretch (120% peak to peak, at 0.5 Hz) on cultured spinal ligament cells derived from OPLL (OPLL cells) and non-OPLL (non-OPLL cells) patients. The mRNA expressions of Cbfa1 (an osteoblast-specific transcription factor), type I collagen, alkaline phosphatase (ALP), osteocalcin and integrin beta1 (a mechanotransducer) were increased by cyclic stretch in OPLL cells, whereas no change was observed in non-OPLL cells. The effects of cyclic stretch on the spinal ligament tissues derived from OPLL and non-OPLL patients were also analyzed by immunohistochemistry using an antibody against Cbfa1. The expression of Cbfa1 was increased by cyclic stretch at the center of the spinal ligament tissues of OPLL patients, whereas no change was observed in the tissues of non-OPLL patients. Furthermore, U0126, a specific inhibitor of MAPK kinase (MEK), suppressed the stretch-induced mRNA expressions of Cbfa1, ALP and type I collagen in OPLL cells. These results suggest that in OPLL cells, mechanical stress is converted by integrin beta1 into intracellular signaling and that Cbfa1 is activated through the MAP kinase pathway. Therefore, we propose that mechanical stress plays a key role in the progression of OPLL through an increase in Cbfa1 expression.

Leukocyte and endothelial adhesion molecule studies in knockout mice

Ischemia and reperfusion of the myocardium initiate an inflammatory response directed against the myocardium, and many studies attribute a significant portion of this injury to leukocytes. Leukocyte and endothelial cell adhesion molecules are responsible for neutrophil-endothelial cell interactions in coronary vasculature following ischemia and reperfusion. Interactions between beta(2)-integrins and intercellular adhesion molecule-1 are responsible for firm adhesion of neutrophils to the coronary endothelium in acute cardiac inflammation. Leukocyte-expressed CD18 plays a crucial role, and genetic deficiency of CD18 significantly attenuates myocardial ischemia-reperfusion injury. Genetic deficiency of intercellular adhesion molecule-1 also minimizes myocardial necrosis following ischemia and reperfusion. The selectin family of adhesion glycoproteins also participates in various phases of leukocyte-endothelial interactions, and studies with P-selectin- and E-selectin-deficient mice have shown attenuation of both neutrophil accumulation and myocardial injury following myocardial ischemia and reperfusion.

Alterations in Granule Matrix and Cell Surface of Focal Adhesion Kinase-Deficient Mast Cells

Focal adhesion kinase (FAK) is a nonreceptor protein tyrosine kinase that plays an important role in many cellular processes and is tyrosine phosphorylated after FcepsilonRI aggregation in mast cells. In mice, null mutation of the fak gene results in a lethal phenotype in which the embryos fail to develop past day 8.5 of gestation. To study the role of FAK in these mast cells, 8.5-day embryos were isolated and placed in culture with IL-3 and stem cell factor (SCF). Although FAK was not required for the development of mast cells in culture, the FAK(-/-) embryo-derived mast cells had several distinct characteristics. Compared with the controls, the mast cells that lack FAK were less metachromatic and by electron microscopy had granules that appeared largely electron lucid, although their histamine content was unchanged. The FAK-deficient mast cells had a reduction in the content of chondroitin/dermatan sulfate, the major glycosaminoglycan component of the granular matrix. The FAK-deficient cells had fewer microvilli that were fused with each other, giving the cell surface a ruffled appearance. There was also a 3-fold increase in the number of cells highly expressing beta(7) integrin. However, signal transduction from the high affinity IgE receptor for the secretion of histamine was similar in the wild-type, heterozygote, and the FAK-deficient cells. The FcepsilonRI-induced tyrosine phosphorylation of paxillin, Crk-associated tyrosine kinase substrate (CAS), and mitogen-activated protein kinase proteins was independent of FAK. These results indicate that FAK plays a role in regulating the glycosaminoglycan content of the secretory granules and influences the cell surface morphology of mast cells.

The stimulus-dependent release of eosinophil cationic protein and eosinophil protein x increases in apoptotic eosinophils

Apoptotic cells are regarded as inert bodies that turn off intracellular processes and functional abilities. To study the changes in the ability of eosinophils to release their granule proteins while undergoing apoptosis. Eosinophils were cultured for up to 72 h. Living cells were separated from the apoptotic cells and their release of eosinophil cationic protein (ECP) and eosinophil protein X (EPX) was measured in response to serum-opsonized sephadex particles and phorbol 12-myristate 12-acetate (PMA). Changes in cell structure were examined by electron microscopy, and surface receptor expression of beta1- and beta2-integrins was investigated by flow cytometry. Stimulus-dependent release of the granule proteins ECP and EPX was found to increase in apoptotic eosinophils, whereas surface expression of beta1- and beta2-integrins was downregulated. Ultrastructural examination revealed that the granules of apoptotic eosinophils were translocated to the periphery of the cell, just beneath the plasma membrane. Apoptotic eosinophils are able to release their toxic granule proteins, which is probably because of the rearrangement of the cytoskeleton and spontaneous translocation of granules to the membrane. Our results suggest that apoptotic eosinophils are potentially harmful cells that have retained their ability to react to certain extracellular stimuli. The findings point to unexpected consequences of eosinophil apoptosis.

Fas activation induces renal tubular epithelial cell beta 8 integrin expression and function in the absence of apoptosis

Cell fate following Fas (CD95) ligand or agonistic anti-Fas antibody stimulation is determined by multiple factors, including Fas expression level, microdomain localization, and modulating cytokines. Highly expressed Fas clusters and activates a canonical apoptosis signaling pathway. In less susceptible cells, Fas transduces apoptosis-independent signals, which are not well defined, but have been linked to inflammation, angiogenesis, and fibrosis. To identify apoptosis-independent Fas pathways, cultured renal tubular epithelial cells were stimulated with agonistic anti-Fas antibodies under conditions that did not cause cell death. Analysis of filter cDNA microarrays revealed beta(8) integrin subunit mRNA induction in Fas-stimulated cells. beta(8) integrin mRNA expression increased within 3-6 h of Fas ligation due to enhanced mRNA stabilization, and mRNA increases were sustained for 48-72 h. Expression of plasma membrane beta(8) integrin, as well as its heterodimer partner alpha(v), was increased by Fas activation with a similar kinetic pattern. Fas-induced alpha(v)beta(8) expression correlated with increased migration to vitronectin, the ligand for alpha(v)beta(8). Results from studies with function-blocking antibodies against other alpha(v)beta integrins or suppression of beta(8) integrin expression by RNA interference demonstrated that induced beta(8) integrin expression mediated Fas-stimulated migration. We conclude that alpha(v)beta(8) integrin induction defines an unexpected role for Fas in cell migration, rather than as a cell death receptor.

Proliferation and invasion factors in HIV-associated dysplastic and nondysplastic oral warts and in oral squamous cell carcinoma: an immunohistochemical and RT-PCR evaluation

OBJECTIVE

Oral warts arising in human immunodeficiency virus (HIV) infection occasionally show marked epithelial dysplasia. However, anecdotal evidence suggests that they do not progress to oral squamous cell carcinoma (SCC). Therefore, we evaluated lesions for expression of proteins (tenascin-C, beta6 integrin, and matrix metalloproteinase-1[MMP1]) that have been identified as important in the invasive phase of oral SCC.

STUDY DESIGN

Twenty-two oral dysplastic warts from 22 patients and 5 oral SCCs were stained for human papillomavirus (HPV) antigen, proliferation protein Ki-67, tenascin-C, beta6, and MMP1 by immunohistochemical methods. For comparison, 5 nondysplastic warts each from HIV-positive and HIV-negative patients and 5 normal mucosa specimens were included. Sections were semiquantitatively assessed, and results were compared. Because MMP1 was the lowest or least expressed interface protein, MMP1 mRNA was quantitatively assessed from formalin-fixed paraffin-embedded tissue in selected cases with quantitative reverse transcription-polymerase chain reaction.

RESULTS

Twenty of 22 dysplastic warts stained positive for human papillomavirus common antigen, and all warts showed high proliferative fractions similar to SCCs. Tenascin-C and beta6 were variably expressed by the dysplastic warts but were consistently expressed at high levels in the SCCs. MMP1 protein levels were negative or low in 20 of 22 in dysplastic warts, but were elevated in 4 of 5 SCCs. MMP1 mRNA analysis indicated that message was low in 4 dysplastic warts and also suggested that protein translation was incomplete in 3 of the warts.

CONCLUSION

We conclude that invasion-associated proteins are underexpressed in oral dysplastic warts in HIV-positive men. However, until these patients are followed for extended periods, the risk of development of SCC from oral dysplastic warts remains unknown.

PPARalpha inhibits TGF-beta-induced beta5 integrin transcription in vascular smooth muscle cells by interacting with Smad4

Integrins play an important role in vascular smooth muscle cell (VSMC) migration, a crucial event in the development of restenosis and atherosclerosis. Transforming growth factor-beta (TGF-beta) is highly expressed in restenotic and atherosclerotic lesions, and known to induce integrin expression. Peroxisome proliferator-activated receptor alpha (PPARalpha), a member of the nuclear receptor superfamily, regulates gene expression in a variety of vascular cells. We investigated the effects of PPARalpha ligands on TGF-beta-induced beta3 and beta5 integrin expression and potential interaction between PPARalpha and TGF-beta signaling. PPARalpha ligands WY-14643 (100 micromol/L) and 5,8,11,14-eicosatetranoic acid (ETYA, 50 micromol/L) inhibited TGF-beta-induced beta5 integrin protein expression by 72+/-6.8% and 73+/-7.1%, respectively (both P<0.05). TGF-beta-stimulated beta3 integrin expression was not affected by PPARalpha ligands. Both PPARalpha ligands also suppressed TGF-beta-induced beta5 integrin mRNA levels. PPARalpha ligands inhibited TGF-beta-inducible transcription of beta5 integrin by an interaction with a TGF-beta response element between nucleotides -63 and -44, which contains a Sp1/Sp3 transcription factor binding site. Nuclear complexes binding to the TGF-beta response region contained Sp1/Sp3 and TGF-beta-regulated Smad 2, 3, and 4 transcription factors. TGF-beta-stimulated Sp1/Smad4 nuclear complex formation was inhibited by WY-14643 and ETYA with a parallel induction of PPARalpha/Smad4 interactions. However, in vitro pull-down experiments failed to demonstrate direct binding between PPARalpha/Smad4. Both PPARalpha ligands blocked PDGF-directed migration of TGF-beta-pretreated VSMCs, a process mediated, in part, by beta5 integrins. The present study demonstrates that PPARalpha activators inhibit TGF-beta-induced beta5 integrin transcription in VSMCs through a novel indirect interaction between ligand-activated PPARalpha and the TGF-beta-regulated Smad4 transcription factors. The full text of this article is available at http://www.circresaha.org.

Bovine gamma delta T cell subsets express distinct patterns of chemokine responsiveness and adhesion molecules: a mechanism for tissue-specific gamma delta T cell subset accumulation

Subsets of gammadelta T cells localize to distinct tissue sites in the absence of exogenous Ag stimulation or development of effector/memory cells. Selective lymphocyte homing from the blood into tissues is controlled by a multistep process involving vascular and lymphocyte adhesion molecules, and G protein-linked chemokine receptors. The role of these mechanisms in the tissue tropism of gammadelta T cells is still poorly understood. In this study, we demonstrate that a subset of gammadelta T cells, most of which express an antigenically distinct TCR and are characterized by coexpression of CD8, selectively accumulated in tissues that expressed high levels of the mucosal vascular addressin, mucosal addressin cell adhesion molecule 1. These cells expressed higher levels of alpha(4)beta(7) integrins than other gammadelta T cell subsets and selectively migrated to the CCR7 ligand secondary lymphoid-tissue chemokine (CCL21). Integrin activation by CCL21 selectively increased CD8(+)gammadelta T cell binding to recombinant mucosal addressin cell adhesion molecule 1. These results suggest that the tropism of circulating CD8(+)gammadelta T cells for mucosal tissues is due, at least in part, to selective developmental expression of adhesion molecules and chemokine receptors.

Dendritic cell appearance and differentiation during early and late stages of rat stomach carcinogenesis

Dendritic cell appearance and differentiation during early and late stages of rat stomach carcinogenesis were studied in the pyloric mucosa. Young male rats were given drinking water with or without N-methyl-N'-nitro-N-nitrosoguanidine (MNNG; 100 mg/liter) for 14 days. Use of competitive RT-PCR and northern blotting showed that MNNG exposure induced 3- to 4-fold greater expression of the genes for integrin beta7 and integrin alphaE2 (identical with antigen OX-62, a dendritic cell marker), as well as three cytokines, IL-4, GM-CSF and TNFalpha, in the stomach pyloric mucosa of resistant Buffalo rats compared to sensitive ACI rats. These genes were minimally expressed in control animals. The results confirm the appearance of dendritic cells in the target pyloric mucosa and suggest the possibility that dendritic cell differentiation and maturation are induced by various cytokines, at least in Buffalo rats. Competitive RT-PCR showed expression of integrin alphaE2 and beta7, MHC class II-associated invariant chain (Ii), MHC class II, B7-1, CD28, GM-CSF and TNFalpha genes in all 12 examined stomach adenocarcinomas and adenomas induced in male Lewis and WKY rats with 30 weeks' MNNG exposure, suggesting the presence of dendritic cells in tumors. OX-62 staining and western blotting for OX-62 also confirmed the presence of dendritic cells in tumors. However, the population of dendritic cells in tumors was less than that in the pyloric mucosa after 14 days' MNNG exposure. The present results suggest that immune defense involving dendritic cells is marshaled from the very early initiation stage during rat stomach cancer development, but is downgraded in developed tumors.