The expression of CD70 and CD80 by gene-modified tumor cells induces an antitumor response depending on the MHC status

The expression of costimulatory molecules such as CD70 or CD80 by gene-modified tumor cells has been shown to enhance the antitumor immune response based mainly on T lymphocytes. However, most human tumors show defects of major histocompatibility complex (MHC) expression, preventing them from being recognized by MHC-restricted T cells. To investigate if coexpression of CD70 and CD80 costimulatory molecules induces comparable antitumor responses in low and high MHC-expressing tumor cells, we used two low immunogenic murine tumor models, the B16.F10 melanoma and the TS/A mammary adenocarcinoma cell lines expressing, respectively, low and high levels of MHC class I molecules. Transfection of both CD70 and CD80 genes resulted in an increased capacity of gene-modified tumor cells to costimulate in vitro the proliferation and cytokine production of optimally activated lymphoid cells. Coexpression of CD70 and CD80 by the two tumor cell lines, TS/A and B16.F10, resulted in both cases in partial regression of subcutaneous tumors. Immunochemical analysis and studies in nude mice showed that, even in the B16.F10 model, T cells had a significant role in the antitumor response induced by combining CD70 and CD80. However, rejection of the CD70/CD80-transfected tumor cells appeared more effective in the MHC class I high TS/A model, leading to a protection against parental tumor cells. B16.F10 and TS/A transfectants were then tested with fibroblasts genetically modified to secrete interleukin-12 (IL-12) as a therapeutic vaccine in mice bearing parental tumors. In the two models tested, the injections of irradiated IL-12 and CD70/CD80 gene-modified cells generated an antitumor response to established tumors leading to the slowing down of the tumor growth rate. Although the mechanisms remain to be defined, these findings suggest that the combination of several immuno-modulatory molecules could provide additional strategies for cancer immuno-gene therapy, even for MHC expression-deficient tumors.

1,3-Diaryl-4,5,6,7-tetrahydro-2H-isoindole derivatives: a new series of potent and selective COX-2 inhibitors in which a sulfonyl group is not a structural requisite

Novel tetrahydro-2H-isoindoles have been prepared and evaluated as inhibitors of the COX-2 isoenzyme. A 1,3-diaryl substitution on the central polycyclic ring system and absence of a sulfonyl moiety are the two structural features of this chemical series. A short and easy synthetic pathway produced several derivatives which were shown to be potent and selective COX-2 vs COX-1 inhibitors (IC(50) = 0. 6-100 nM for COX-2, 100->1000 nM for COX-1). Structural modifications established that a bicyclic ring appended to the pyrrole nucleus and 4,4'-difluoro substitution on the phenyl rings were optimal for high inhibitory potency. Activity was confirmed in the human whole blood assay and subsequently in the murine air-pouch model in which in vivo PGE2 inhibitory activity was evaluated with respect to gastric tolerance (ED(50) for inhibition of exudate PGE2 of 3 mg/kg and gastric PGE2 of 20 mg/kg). Gastric tolerance was further assessed after administration to mice of high doses (up to 400 mg/kg) of the inhibitors by measurement of gastric damage. This panel of studies allowed selection of a number of tetrahydro-2H-isoindoles which were compared in the adjuvant-induced arthritis model. Compounds 32 and 37 showed the most potent activity with ED(50) values for edema inhibition in the noninjected paw of 0. 35 and 0.15 mg/kg/day, respectively, after oral administration. In addition, this interesting antiinflammatory profile was accompanied by a protective effect against arthritis-induced osteopenia, the decrease being 50% with a dose of 0.25 mg/kg/day.

Short- and long-term risk factors for sudden death in patients with stable angina

Sudden death is most common and often the first manifestation of coronary heart disease although its risk is difficult to predict. It has been studied mainly in patients with severe ventricular arrhythmia or recent myocardial infarction, but little is known about the different risk factors for short- and long-term risk of sudden death in patients with stable angina. To assess risk factors for sudden death in patients with stable angina and angiographically proven coronary artery disease, 319 consecutive patients were recruited prospectively and followed-up. Patients with clinical heart failure or recent myocardial infarction were excluded. Clinical, angiographic and biological variables were recorded. The association between each variable and the risk of sudden death was assessed in univariate and logistic multivariate analysis. There were 25 sudden deaths during the follow-up period (97+/-29 months). The univariate predictors in the short-term (2 years) were: peripheral arterial disease, left ventricular hypertrophy, low density lipoprotein cholesterol and ejection fraction. The independent predictors were: peripheral arterial disease (relative risk: 6.3), ejection fraction (relative risk 1.05) and low density lipoprotein (relative risk: 1.8). In the long-term (8-10 years), body mass index, coronary score, ejection fraction and fibrinogen were univariate predictors. Only body mass index (relative risk: 1. 2), ejection fraction (relative risk: 1.06) and fibrinogen (relative risk: 2) remained independent predictors. The risk factors for sudden death in stable angina were time-dependent, peripheral arterial disease appeared as the best predictor with LDL for short time, and body mass index (obesity: index >27) and fibrinogen for long time. Ejection fraction was the only time-independent predictor.

An overlapping CArG/octamer element is required for regulation of desmin gene transcription in arterial smooth muscle cells

The desmin gene encodes an intermediate filament protein that is present in skeletal, cardiac, and smooth muscle cells. This study shows that the 4-kb upstream region of the murine desmin promoter directs expression of a lacZ reporter gene throughout the heart from E7.5 and in skeletal muscle and vascular smooth muscle cells from E9. 5. The distal fragment (-4005/-2495) is active in arterial smooth muscle cells but not in venous smooth muscle cells or in the heart in vivo. It contains a CArG/octamer overlapping element (designated CArG4) that can bind the serum response factor (SRF) and an Oct-like factor. The desmin distal fragment can replace a SM22alpha regulatory region (-445/-126) that contains two CArG boxes, to cis-activate a minimal (-125/+65) SM22alpha promoter fragment in arterial smooth muscle cells of transgenic embryos. lacZ expression was abolished when mutations were introduced into the desmin CArG4 element that abolished the binding of SRF and/or Oct-like factor. These data suggest that a new type of combined CArG/octamer element plays a prominent role in the regulation of the desmin gene in arterial smooth muscle cells, and SRF and Oct-like factor could cooperate to drive specific expression in these cells.

Emotional, physical and sexual violence against women before or during pregnancy

The objective of this study was to determine the prevalence of emotional, sexual or physical violence reported by women delivered at the University Hospital Geneva, a tertiary care university teaching hospital, where about 3,000 women are delivered each year. This study showed that prevalence of violence against women is high, and is severely underestimated by health case providers.

Severe oesophagitis after allogeneic bone marrow transplantation for Fanconi's anemia

Allogeneic bone marrow transplantation (BMT) is an effective treatment for Fanconi's anemia (FA) but it requires a dose reduction of alkylating agents used for conditioning because of the increased sensitivity of FA cells to DNA cross-linking agents. Oesophageal damage has not previously been described as a complication after allogeneic BMT for this indication. We report five cases of severe oesophagitis with stenosis in patients transplanted for FA. It occurred either early, or more surprisingly, several years after BMT and could have easily been misdiagnosed. It could be explained by hypersensitivity of the FA mucosal cells to cytotoxic agents despite the reduced doses of cyclophosphamide and irradiation or to non diagnosed congenital abnormalities of the oesophagogastric junction. However, the evolution of the oesophageal disease was favorable in all, and none of the patients developed secondary cancer. Awareness of this complication will lead to earlier diagnosis and treatment of oesophageal stenosis and related malnutrition.

Freeze-drying allows double nonradioactive ISH and antigenic labeling

Because tissue freeze-drying is an excellent way to preserve antigenic conformation, we have tested the feasibility of this technique to reveal nonradioactive in situ hybridization (ISH) of tissue mRNA. We have compared mRNA detection after different methods of tissue preservation, freeze-drying, cryosectioning, and formaldehyde or methanol fixation. Our results show that nonradioactive ISH is more sensitive for tissues preserved by freeze-drying than for other tissue preparations. We have demonstrated that freeze-drying allows combination of ISH and immunohistochemistry for simultaneous detection of mRNA and antigen because with this technique of tissue preservation ISH does not affect the sensitivity or the amount of the detected antigens. This work underscores the fact that tissue freeze-drying is an easy, convenient, and reliable technique for both ISH and immunohistochemistry and achieves excellent structural conditions for nonradioactive detection.

Early and long-term (one-year) effects of the association of aspirin and oral anticoagulant on thrombi and morbidity after replacement of the mitral valve with the St. Jude medical prosthesis: a clinical and transesophageal echocardiographic study

OBJECTIVES

The aim of the study was to test the value of low dose aspirin associated with standard oral anticoagulants (OAC) after mechanical mitral valve replacement (MMRV) to reduce strands, thrombi and thromboembolic events.

BACKGROUND

Strands and thrombi are thought to increase the risk of embolic events after MMVR, particularly in the immediate postoperative period.

METHODS

Two hundred twenty-nine patients were prospectively recruited: 109 patients (group A+) were randomly assigned to aspirin (200 mg per day) with OAC and 120 patients (group A-) to OAC alone (international normalized ratio 2.5 to 3.5). All patients were subjected to multiplane transesophageal echocardiography at nine days and five months and were followed up for one year.

RESULTS

At nine days and five months, there was a high and comparable incidence of strands in the two groups (group A+: 44%, 58%; group A-: 49%, 63%). However, the incidence of nonobstructive periprosthetic valve thrombi was significantly lower in group A+ at 9 days: 5% versus 13%, p = 0.03. Total thromboembolic events were reduced in group A+ (9% vs. 25%, p = 0.004) although there was an increased incidence of gastrointestinal hemorrhage (7% vs. 0%). Overall mortality was 9% in group A+ and 4% in group A-. Valve-related events were similar in both groups. Early thrombi, but not strands, were associated with higher morbidity, especially thromboembolic events (30% vs. 13%, p = 0.003).

CONCLUSIONS

One year after MMVR, the association of aspirin with OAC reduced thrombi and thromboembolic events, but not morbidity, due to an increase in hemorrhagic complications.

Effects of ceramide on apoptosis, proteoglycan degradation, and matrix metalloproteinase expression in rabbit articular cartilage

Cartilage loss in osteoarthritis is characterized by matrix degradation and chondrocyte death. The lipid messenger ceramide is implicated in signal transduction of the catabolic cytokines tumor necrosis factor (TNF) and interleukin-1 (IL-1), as well as in apoptosis. The aim of this study was to examine the in vitro effects of ceramide on proteoglycan degradation, matrix-metalloproteinase (MMP) expression and activity, and chondrocyte apoptosis in rabbit articular cartilage. Cell-permeant ceramide C(2) stimulated proteoglycan degradation in cartilage explants starting from 3 x 10(-5) M, with 100% increase at the dose of 10(-4) M. This effect was probably due to MMPs since it was blocked by the MMP inhibitor batimastat. Furthermore, in isolated chondrocytes, C(2) stimulated the expression of MMP-1, 3, and 13 at the mRNA level, MMP activity, and MMP-3 production. Ceramide also caused chondrocyte apoptosis at doses ranging from 10(-5) to 10(-4) M. This study supports the hypothesis that ceramide might play a mediatory role in both matrix degradation and apoptosis in processes of cartilage loss such as those observed in osteoarthritis.

Familial dilated cardiomyopathy: clinical features in French families

The aims of the study were to analyze the clinical features, the penetrance and the mode of inheritance of 13 French families with dilated cardiomyopathy using diagnostic criteria recently established by a European collaboration.

METHODS

Screening consisted of physical examination, ECG and Echo of all the probands first degree relatives (n = 118). Using major Echo criteria [ejection fraction (EF) < 45% or FS < 25% and left ventricular diameter (LVD) > 117% of the predictive value], or combined minor Echo/ECG criteria, relatives were classified as affected, unknown or healthy.

RESULTS

(1) Adult affected relatives (n = 31) were identified with major Echo criteria in 74% of cases, and with combined minor Echo/ECG criteria in 26% of cases. (2) In the unknown relatives (n = 21), the most common abnormality was an isolated left ventricular dilation (67%). (3) Mode of inheritance was autosomal dominant (AD) in 11 families and possibly autosomal recessive in two. (4) In AD families, the penetrance was incomplete in adults (72%), age-related (O.R.: 1.3 per 10 years; 95% CI 1.03-1.56) and sex-related [greater in men (87%) than in women (61%), actuarial survival curve: P<0.002]. (5) Mortality related to end stage heart failure was 2.2 times as high as mortality related to sudden death (11% vs. 5%).

CONCLUSIONS

(1) In the absence of a specific phenotype of FDC, the characterization of relatives appears more accurate when minor criteria were added. (2) Since high mortality (16%) and incomplete penetrance frequently give rise to small nuclei of clinically affected and alive relatives per family, the accurate model of penetrance that we proposed might be helpful in the future to enhance the statistical power of linkage analysis in this disease.

[Coronary atherectomy. An essential tool for specific indications]

Technological advances in the manufacturing of stents have extended the indications of angioplasty and considerably reduced the immediate complications, death and myocardial infarction. Nevertheless, intra-stent restenosis remains a problem and some complex lesions are still inaccessible. Atherectomy has not been shown to be effective in limiting restenosis but it has a primordial role in the treatment of lesions of bifurcation and could improve long-term results as a complement of angioplasty and stenting. Rotational atherectomy is still useful, even essential, for lesions which cannot be passed with the balloon and for calcified plaques of atheroma. A possible new indication may be the treatment of intra-stent stenosis. The indications of directional atherectomy are more limited, mainly non-calcified ostial stenosis and of bifurcations of large arteries. The association with stenting has given encouraging results which require confirmation. These techniques have a place in the in the angioplasty physician's arsenal even though they are reserved for specific anatomical situations.

The farnesyltransferase inhibitor FTI-277 suppresses the 24-kDa FGF2-induced radioresistance in HeLa cells expressing wild-type RAS

In this paper, we describe the effect of the inhibitor of farnesyltransferase (FTI-277) on radioresistance induced by the 24-kDa isoform of FGF2 in human cells expressing wild-type RAS. Treatment with FTI-277 (20 microM) for 48 h prior to irradiation led to a significant decrease in survival of radioresistant cells expressing the 24-kDa isoform (HeLa 3A) but had no effect on the survival of control cells (HeLa PINA). The radiosensitizing effect of FTI-277 is accompanied by a stimulation of postmitotic cell death in HeLa 3A cells and by a reduction in G(2)/M-phase arrest in both cell types. These results clearly demonstrate that at least one farnesylated protein is involved in the regulation of the radioresistance induced by the 24-kDa isoform of FGF2. Furthermore, the radiation-induced G(2)/M-phase arrest is also under the control of farnesylated protein. This work also demonstrates that FTase inhibitors may be effective radiosensitizers of certain human tumors with wild-type RAS.

Trembler as a mouse model of CMT1A?

The Trembler mouse suffers from a dominantly inherited autosomal mutation that results in an abnormal myelination of the peripheral nervous system. Biochemical studies have shown that dysmyelination is the primary event, demyelination being a late-occurring process. The expression of myelin protein genes has been studied. The steady-state levels for PMP22 mRNA represent 10 and 5% of normal values in the nerves of heterozygous and homozygous Trembler, respectively. This is due to a reduced expression of the specific transcript driven by the promoter 1 of the PMP22 gene. Collective results indicate that Trembler dysmyelination is not necessarily the consequence of a large accumulation of the mutated PMP22 protein. Moreover, it appears that the situation in the Trembler is different from that encountered in most CMT1A patients, where an increased PMP22 gene dosage is responsible for the disease. Therefore, the Trembler mutant is perhaps not an ideal model for this human neuropathy.

Evidence of early subchondral bone changes in the meniscectomized guinea pig. A densitometric study using dual-energy X-ray absorptiometry subregional analysis

OBJECTIVE

Subchondral bone changes are thought to be an important aetiological element in the pathogenesis of osteoarthritis (OA). To confirm this hypothesis in the meniscectomized (MNX) guinea pig model, bone densitometry was performed in the subchondral bone of the distal femur.

METHODS

MNX and sham-operated (SH) guinea pigs were studied 1 and 3 months after partial meniscectomy at the medial side of the left knee. Bone mineral density was measured at the lateral (BMD-L) and medial (BMD-M) sides of the distal femur using dual-energy X-ray absorptiometry (DXA). BMD-M was then compared to the bone volume evaluated by histomorphometry at the medial epiphyseal part of the proximal tibia (BV-M).

RESULTS

One month after operation, in MNX animals left femur BMD-M was significantly lower than in the contralateral femur (-9%, P< 0.01) and than in the left femur of SH (-11%, P< 0.01). By contrast, 3 months after meniscectomy BMD-M was higher in the femur than in the contralateral femur (+4%, P< 0.05); BV-M tended to be higher on the left than on the right side (+4%, P< 0.06), and was significantly correlated with BMD-M at the 2 grouped time points: r=0.74 (P< 0.001).

CONCLUSIONS

These data emphasize the usefulness of DXA as a simple tool to assess subchondral bone changes at the OA-affected side of the femur and reveal typical variations of bone metabolism in the initiation of OA pathology in the MNX guinea pig: early bone loss at the subchondral level followed by increased bone density.

IL-2-dependent expression of genes involved in cytoskeleton organization, oncogene regulation, and transcriptional control

IL-2 induces growth, differentiation, and/or apoptosis of lymphoid cells. To study further the molecular basis of IL-2 function, we used a cDNA subtraction approach involving a cell line grown in IL-2 or IL-4. From the corresponding library, 66 nonredundant sequences were characterized; 16 of them encode identified proteins. The kinetics of in vitro expression of 8 selected sequences, the functions of which could be associated with IL-2-induced T cell activation/differentiation, was investigated using an IL-2-dependent T cell line. IL-2 increased the expression of cytoskeleton proteins (alpha-tubulin), oncogene-regulating proteins (CCCTC-binding factor, Jun inhibitor factor-1), and transcription factors (E2F-4, cyclic AMP-responsive element-binding protein, zhx-1). IL-2 also regulated the expression of genes coding for multifunctional proteins, e.g., beta-catenin and nucleolin. These results were verified using Con A-induced T cell blasts stimulated or not by IL-2. The in vivo expression of four of these genes was also analyzed in spleen and lymph node cells of IL-2-deficient and MRL/lpr mice, which both have high numbers of activated cells, but the latter have intact IL-2 expression. The expression of beta-catenin, CCCTC-binding factor, Jun inhibitor factor-1, and nucleolin was significantly higher in MRL/lpr animals. A similar analysis of thymocytes from IL-2-/- and IL-2+/- mice demonstrated the same expression patterns of the 4 sequences in these strains. The expression of the IL-2-induced genes described herein is similar to the regulatory pattern of IL-2R alpha. Taken together, our data provide additional evidence for the pleiotropic action of IL-2 in the periphery and IL-2 independence of molecular processes involved in thymocyte differentiation.

Immunohistological and ultrastructural analysis of the intimal thickening in coarctation of human aorta

OBJECTIVES

The histological nature and characteristics of aortic coarctation are not clearly defined, the aim of this study is to analyse intimal thickening in aortic coarctation.

METHODS

In order to characterize the components of intimal thickening in coarctation, narrowed segments of aorta obtained after surgery from ten children were examined immunocytochemically and by electron microscopy.

RESULTS

Histological analysis of aortic coarctation demonstrated a widened subendothelial region with separation of endothelial cells from the internal elastic lamina. Masson's trichrome staining showed a marked increase in extracellular matrix and cell numbers in the intimal thickening compared with normal aorta. Cellular component analysis demonstrated invagination of the intima by smooth muscle actin-positive cells, with a fragmentation of the internal elastic lamina. No proliferating smooth muscle and inflammatory cells were identified in the intima. In order to characterize the smooth muscle cell phenotypes, various smooth muscle cell markers were sought using specific monoclonal antibodies: alpha-smooth muscle actin, smooth muscle-myosin heavy chain, heavy caldesmon, desmin. In moderate coarcted aorta, at least two distinct smooth muscle phenotypes were identified. In the juxtamedial part of the intima smooth muscle, cells were differentiated and expressed all smooth muscle markers; in the subendothelial part of the intimal thickening, the majority of smooth muscle cells expressed only alpha-smooth muscle actin and appeared dedifferentiated. In regions of marked stenosis, a strong expression of smooth muscle-myosin heavy chain, and heavy caldesmon in the intimal thickening pointed to the presence of redifferentiated smooth muscle cells, not still expressing desmin. Electron microscopic examination also revealed a variety of smooth muscle cell phenotypes in the intimal thickening. In the superficial layer, smooth muscle cells appeared to be in the synthetic state, while in the deeper part, both synthetic and contractile components were identified.

CONCLUSIONS

These observations indicated that human coarctation was characterized by intimal recruitment of non-proliferating smooth muscle cells with dedifferentiated phenotype. However, the presence of smooth muscle cells with an intermediate phenotype in the narrowest part of the coarctation suggest that the redifferentiation process could participate in the pathogenesis of aortic coarctation.

MRI dosimetry: a fast quantitative MRI method to determine 3D absorbed dose distributions

RATIONALE AND OBJECTIVES

Magnetic resonance imaging (MRI) techniques seem to be very promising for 3D dosimetry studies, but long imaging acquisition time limits their use. A new fast T1 mapping protocol, easy to implement on a conventional MR imager, has been used to determine dose distributions on Fricke gels.

METHODS

The method has been tested on manganese chloride (MnCl2) doped ferrous gelatin gels. The T1 measuring times range from 1 minute 40 seconds to 3 minutes 30 seconds for a 256x256 matrix image.

RESULTS

The two- and three-dimensional profiles agree with those obtained with conventional dosimetry techniques (ion chambers). The precision and the spatial resolution principally depend on the signal-to-noise ratio of the used imaging RF coil. For example, for a surface coil, the accuracy is about 2.5% with a 1.56 mm spatial resolution.

CONCLUSION

These preliminary results support the feasibility of the proposed technique for accurate MRI dosimetry studies and also have potential for various clinical quantitative MRI applications.

Phosphorescent platinum/palladium coproporphyrins for time-resolved luminescence microscopy

Streptavidin and antibodies were labeled with phosphorescent platinum and palladium coproporphyrin. The optimal conjugates were selected on the basis of spectroscopic analysis (molar extinction coefficient, quantum yield, lifetime) and using ELISA assays to determine the retention of biological activity and immunospecificity. They were subsequently tested for the detection of prostate-specific antigen, glucagon, human androgen receptor, p53, and glutathione transferase in strongly autofluorescent tissues. Furthermore, platinum and palladium coproporphyrin-labeled dUTPs were synthesized for the enzymatic labeling of DNA probes. Porphyrin-labeled DNA probes and porphyrin-labeled streptavidin conjugates were evaluated for DNA in situ hybridization on metaphase spreads, using direct and indirect methods, respectively. The developed in situ detection technology is shown to be applicable not only in mammals but also in plants. A modular- based time-resolved microscope was constructed and used for the evaluation of porphyrin-stained samples. The time-resolved module was found suitable for detection of antigens and DNA targets in an autofluorescent environment. Higher image contrasts were generally obtained in comparison with conventional detection systems (e.g., fourfold improvement in detection of glutathione transferase).

Detection of cell and tissue surface antigens using up-converting phosphors: a new reporter technology

A novel luminescent reporter for the sensitive detection of antigens in tissue sections or on cell membranes is described. It consists of submicron-size phosphor crystals (0.2-0.4 microm), which are surface labeled with avidin or antibodies and capable of binding specifically to antigens on intact cells or in tissue sections. These phosphor reporters exhibit two-photon, anti-Stokes luminescence by up-converting infrared to visible light and are named Up-converting Phosphor Technology (UPT). They typically consist of yttriumoxysulfides doped with two different lanthanides exhibiting photostable, strong emission in the visible (blue, green, and red) upon excitation in the infrared. This report describes the conjugation of phosphor particles to NeutrAvidin with the subsequent use of this conjugate in a model system consisting of prostate-specific antigen in tissue sections and the CD4 membrane antigen on human lymphocytes. An epi-illumination fluorescence microscope was adapted to provide near-IR excitation using a xenon lamp for visualization of the visible emission. Advantages of UPT are (i) permanent, strong, anti-Stokes emission of discrete wavelengths; (ii) unmatched contrast in biological specimens due to the absence of autofluorescence upon excitation with IR light; (iii) simultaneous detection of multiple target analytes; and (iv) low-cost microscope modifications. The new methodology has not only high potential value in diagnostic pathology as described here, but may offer advantages for the detection of proteins or nucleic acids when applied to molecular biology, genomic research, virology, and microbiology.

Vascular cell adhesion molecule-1 gene expression during human smooth muscle cell differentiation is independent of NF-kappaB activation

Vascular cell adhesion molecule-1 (VCAM-1) gene expression in cytokine-activated cells depends on two kappaB elements. Since VCAM-1 expression appears developmentally regulated and cytokine-inducible in smooth muscle cells (SMCs), we have studied the role of NF-kappaB in differentiated SMC VCAM-1 expression. Confluent SMCs were cultured either in a serum-free medium in order to induce differentiation, or in medium with serum, stimulated or not by tumor necrosis factor alpha (TNF-alpha). The expression of smooth muscle myosin heavy chain, a SMC marker, and VCAM-1 was induced concomitantly in serum-free medium, whereas only VCAM-1 expression was induced by cytokine-treatment. We showed that the p50 and p65 subunits of NF-kappaB were localized in the cytoplasm of differentiating SMCs, whereas they were translocated into the nucleus of TNF-alpha-activated SMCs. Electrophoretic mobility shift assays with VCAM-1 gene kappaB elements failed to detect any induction of DNA-protein complex with nuclear extracts of differentiating SMCs in contrast to the cytokine-activated SMC nuclear extracts. Furthermore, VCAM-1 mRNA induction was inhibited in TNF-alpha-stimulated SMCs, but not in differentiating SMCs, by pyrrolidine dithiocarbamate, an inhibitor of NF-kappaB protein activation. Taken together, these findings suggest that in contrast to TNF-alpha activation, NF-kappaB is not involved in VCAM-1 gene expression during SMC differentiation.