Biomedical subjects

S Iacobelli

Publications and source records attributed to S Iacobelli.

At least 19 recordsLinked to original sources

PubMed2001

PARP co-activates B-MYB through enhanced phosphorylation at cyclin/cdk2 sites.

PARP is a multifunctional protein that can affect genome stability, transcription control, telomere length and cell death. Recently we have reported that PARP binds to and enhances B-MYB transactivating potential. B-MYB is a potentially oncogenic transcription factor involved in mammalian cell proliferation, survival and differentiation. B-MYB gene expression is growth regulated and B-MYB protein is phosphorylated during S phase by cyclin A or E/cdk2 kinase, resulting in augmented transactivating potential. Here we show that PARP induces phosphorylation of B-MYB protein at cdk2 phosphorylation sites, since a B-MYB protein with mutated cdk2 phosphorylation sites is refractory to PARP-induced phosphorylation and co-activation in mammalian cells. We propose that PARP functions as a B-MYB co-factor by promoting cyclin/cdk2-dependent B-MYB phosphorylation. These results highlight a novel role for PARP as a factor that integrates cyclin-dependent kinases signaling with gene transcription.

CDC2-CDC28 Kinases↗

PubMed2001

Glycoprotein 90K/MAC-2BP interacts with galectin-1 and mediates galectin-1-induced cell aggregation.

The glycoprotein 90K was originally described as a tumor-secreted antigen and subsequently found to have immunostimulatory activity as well as other possible functions. This protein interacts with an endogenous lectin, galectin-3, and may play a role in tumor metastasis through this interaction. Because 90K is heavily glycosylated, it may also interact with other members of the galectin family, which would contribute to the multifunctionality of 90K. To test this possibility, we studied the recognition of 90K by galectin-1, which, like galectin-3, has been associated with neoplastic transformation. In a solid-phase binding assay, human recombinant galectin-1 bound immobilized human recombinant 90K in a fashion that was inhibitable by lactose. Galectins 1 and 3 appeared to bind to separate sites on 90K because they did not affect the binding of each other. The dissociation constant of galectin-1 to 90K was on the order of 10(-7) M. Galectin-1 also induced aggregation of a human melanoma cell line, A375, in a carbohydrate-dependent manner, and this appeared to be mediated, at least in part, by 90K expressed on A375 cells, since it was inhibitable by a specific anti-90K monoclonal antibody. We conclude that 90K interacts with both galectin-1 and galectin-3 and both interactions contribute to the formation of multicell aggregates. Because both of these galectins as well as 90K are often over-expressed in neoplasm, these interactions may occur in the setting of various carcinomas and contribute to their progression and metastasis.

3T3 Cells↗

PubMed2000

Adhesion to 90K (Mac-2 BP) as a mechanism for lymphoma drug resistance in vivo.

A cell-adhesive protein of the human serum, 90K binds galactin-3, beta1-integrins, collagens, and fibronectin, and it is of importance in cell-cell and cell-extracellular matrix adhesion. Serum 90K levels in 137 patients with lymphoma were measured by enzyme-linked immunosorbent assay. Compared with healthy controls, pretreatment serum 90K levels in patients with lymphoma were elevated (P <.001). Of 97 patients who showed objective response to treatment, 20 (21%) had pretreatment 90K levels above the normal cutoff compared with 17 (53%) of 32 patients who did not respond (P =.002). When used as a plastic-immobilized substrate, 90K caused a significant reduction in chemotherapy-induced apoptosis of Jurkat T lymphoma cells. This finding could explain the lack of response in lymphoma patients with high 90K serum levels.

Adolescent↗

PubMed2000

Galectin-3 overexpression protects from cell damage and death by influencing mitochondrial homeostasis.

Galectins are a family of proteins involved in several cell processes, including their survival and death. Galectin-3 has in particular been described as an anti-apoptotic molecule entangled with a number of subcellular activities including anoikis resistance. In this work we partially address the mechanisms underlying this activity pointing at two key factors in injury progression: the alteration of mitochondrial membrane potential and the formation of reactive oxygen species. Overexpression of galectin-3 appears in fact to exert a protective effect towards both these events. On the basis of these data, we propose a reappraisal of the role of galectin-3 as a regulator of mitochondrial homeostasis.

Antigens, Differentiation↗

PubMed2000

Lack of mother-to-child HIV-1 transmission is associated with elevated serum levels of 90 K immune modulatory protein.

BACKGROUND: 90 K is a secreted human serum glycoprotein with immune modulatory activity. METHODS: Serum 90 K levels were determined by an enzyme-linked immunosorbent assay in 19 HIV-1-infected mothers at the time of delivery, in their new-borns (11 HIV-1 infected and eight uninfected), in 26 HIV-1-uninfected mothers and in 86 new-borns of HIV-1-uninfected mothers. RESULTS: 90 K levels in HIV-1-infected transmissive mothers (22.4 +/- 13.9 microg/ml) were similar to those of HIV-1-uninfected mothers (21.1 +/- 7.6 microg/ml; P = 0.715), but lower than those of HIV-1-infected non-transmissive mothers (45.5 +/- 24.8 microg/ml; P = 0.019). The levels were higher in HIV-1-uninfected (47.6 +/- 22.4 mg/ml) than HIV-1-infected (23.7 +/- 15.6 microg/ml; P = 0.014) new-borns of HIV-1-infected mothers. The new-borns of HIV-1-uninfected mothers had lower levels (11.7 +/- 5.3 microg/ml) than both HIV-1-infected and HIV-1-uninfected new-borns of HIV-1-infected mothers (all differences, P < 0.001). CONCLUSION: These results suggest that high 90 K protein serum levels in HIV-1-infected mothers and their new-borns are associated with lack of mother-to-child HIV-1 transmission.

Adult↗

PubMed2000

Galectin-3 overexpression protects from apoptosis by improving cell adhesion properties.

Galectin-3 is a carbohydrate-binding protein endowed with affinity for beta-galactosides. It plays a role in cell-cell and cell-matrix interactions. Furthermore, it has been hypothesized to be involved in tumor progression and metastasis. To address the role of galectin-3 in the invasive and metastatic processes, we stably overexpressed galectin-3 in human breast carcinoma cell lines, and we evaluated the influence of elevated galectin-3 expression on several cell features, including cellular homotypic and heterotypic interactions and cell survival. No differences in various parameters related with cell growth features and proliferation were detected. By contrast, we found that galectin-3 overexpressing cells, with respect to low galectin-3 expressing cells, exerted: (1) a significantly enhanced adhesion to laminin, fibronectin and vitronectin exerted both directly or via increased expression of specific integrins, e.g., alpha-4 and beta-7; (2) a remodeling of those cytoskeletal elements associated with cell spreading, i.e., microfilaments; (3) an enhanced survival upon exposure to different apoptotic stimuli, such as cytokine and radiation. Collectively, our results indicate that overexpression of galectin-3 may play a role in tumor cell invasion and metastasis by specifically influencing cell adhesion to the extracellular matrix. This may confer selective survival advantage and resistance to the particular homeless-induced apoptosis called anoikia.

Antigens, Differentiation↗

PubMed2000

Elevated plasma levels of 90K (Mac-2 BP) immunostimulatory glycoprotein in HIV-1-infected children.

90K is a secreted serum glycoprotein with immune stimulatory activity. In this study, 90K plasma levels were determined by an enzyme-linked immunosorbent assay in 18 HIV-1-infected children and 10 uninfected control children. 90K levels in HIV-1-infected children (median, 12.5 microg/ml) were higher than in HIV-1 uninfected control group (6.3 microg/ml; P < 0.05). 90K levels of HIV-1-infected children classified as stage B and C (median, 15.0 microg/ml and 22.7 microg/ml, respectively) were higher compared to children with stage A disease (median, 7.0 microg/ml; P < 0.05). A positive correlation (r = 0.5; P < 0.05) was found between 90K levels and HIV-1 RNA levels in 137 plasma samples of 18 HIV-1-infected children collected during a period of 1 year. No correlation was found between 90K levels and CD4 cell counts. These results suggest that 90K plasma levels may represent a novel marker of disease progression in HIV-1-infected children.

Adjuvants, Immunologic↗

PubMed2000

Concentrations of galectin-3 in the sera of normal controls and cancer patients.

Galectin-3, a member of the beta-galactoside-binding animal lectins, has been implicated in tumor invasion and metastasis. Using an immunoligand assay, we assessed the circulating levels of galectin-3 in sera from cancer patients as well as from healthy controls. Low serum levels of galectin-3 were detected in healthy individuals (median, 62 ng/ml; range, 20-313 ng/ml; 95th percentile, 184.3 ng/ml). Compared with healthy individuals, galectin-3 serum levels in patients with breast, gastrointestinal, lung, or ovarian cancer, melanoma, and non-Hodgkin's lymphoma were significantly elevated (P = 0.014). Moreover, galectin-3 concentrations in sera from patients with metastatic disease were higher than in sera from patients with localized tumors. Maximum serum concentrations of galectin-3 (median, 320 ng/ml; range, 20-950 ng/ml) were found in patients with metastatic gastrointestinal carcinoma. These results suggest that circulating galectin-3 may play a role in tumor progression. The possibility of using this assay in early-stage cancer to predict metastasis should be studied.

Antibodies, Monoclonal↗

PubMed1999

Isolation and functional characterization of the human 90K promoter.

90K is a secreted protein thought to be involved in the body's defense against pathogens and cancer. To elucidate its transcriptional regulation, the promoter of human 90K (HGMW-approved symbol LGAL S3BP) was isolated and characterized. Analysis of the 3. 3-kb 5'-flanking region revealed that it is a TATA-less promoter, but neither GC-rich nor dependent on SP1 sites. RNase protection assays detected one major transcription start site (+1) and several minor transcription start sites upstream and downstream. Deletion studies defined a minimal promoter (-103 --> -49) and indirectly suggested positive synergism between different elements within it. Consistent with the proposed function of 90K, its promoter activity could be stimulated by poly(I). poly(C), mimicking viral infection. Two regions mediating induction by poly(I). poly(C) (-171 --> -112, -32 --> 46) were identified by deletion mutants. A small region around the minimal promoter (-99 --> -12) was highly homologous between human and mouse. While both human and mouse minimal promoters contained an interferon-responsive element (IRF-E), the human minimal promoter was not inducible by poly(I). poly(C) in contrast to that of the mouse. Point mutations 30 bp upstream of the IRF-E, however, conferred inducibility to the human minimal promoter, suggesting interaction between different promoter elements.

3T3 Cells↗

PubMed1999

Endocrinological and clinical evaluation of two depot formulations of leuprolide acetate in pre- and perimenopausal breast cancer patients.

PURPOSE: To evaluate the endocrinological and clinical activity of a new slow-release formulation of leuprolide acetate in breast cancer patients. METHODS: A total of 50 pre- or perimenopausal patients with early- or late-stage breast cancer who were candidates for endocrine treatment were included in the study and randomly allocated to receive either 3.75 mg of leuprolide acetate every month or 11.25 mg of leuprolide acetate every 3 months. Patients were treated until disease recurrence or progression or for a maximum of 24 months. Treatment outcome, side effects, and serum levels of gonadotrophins, estradiol, progesterone, and delta4-androstenedione were analyzed at different time points. RESULTS: In all, 23 patients were allocated to the monthly formulation and 27, to the 3-monthly formulation. The median time on treatment was comparable. There was no evidence of any difference in clinical outcome or drug-induced side effects, hot flushes being recorded in about 50% of patients in both groups. Altogether, 35 patients were actively menstruating at the beginning of treatment; all of them became amenorrhoic after 3 months and remained so until treatment with leuprolide was continued, irrespective of the allocated treatment. All endocrine parameters, particularly estradiol levels, were suppressed to a similar extent. CONCLUSIONS: The present results indicate that the two formulations exert a comparable estrogen-suppressive effect and warrant further study of the 3-monthly formulation of leuprolide acetate in breast cancer patients.

Adult↗

PubMed1999

Elevated levels of circulating immunostimulatory 90K in Henoch-Schoenlein purpura.

In order to clarify the immunologic reaction present in Henoch-Schoenlein purpura (HSP), 20 children (11 boys and 9 girls; median age, 5.8 +/- 2.8 years) with HSP and 20 sex- and age-matched healthy children were studied. The 90K/Mac-2 BP serum concentrations were significantly higher in the patients than in the healthy controls (12.5 +/- 7.5 vs 4.5 +/- 2.7 micrograms/ml, respectively; P < 0.0001). 90K/Mac-2 BP values higher than the cutoff value were observed in 13 of 20 (65%) patient. The soluble intercellular adhesion molecule 1 concentrations were significantly higher in HSP patients than controls (P < 0.0001), with mean values of 1631 +/- 703 and 85 +/- 16 ng/ml, respectively. The 90K/Mac-2 BP serum levels were significantly correlated with soluble intercellular adhesion molecule 1 (r = 0.90, P < 0.0001). Although the underlying causes of these immunological abnormalities are unclear, these observations suggest that the 90K/Mac-2 BP protein may play a role in the immunological reactions involved in the development of HSP.

Age Distribution↗

PubMed1999

Human milk 90K (Mac-2 BP): possible protective effects against acute respiratory infections.

Eighty-six children fed human milk were followed prospectively from birth to 12 months of age to assess the effect of milk 90K, a secreted glycoprotein with immune-stimulatory properties, on development of acute respiratory infections (ARI). The level of human milk 90K was inversely related to episodes of ARI (r = - 0.34; P = 0.001). The average 90K level in human milk fed to children who did not develop ARI was significantly higher than in milk fed to children in whom infection occurred on multiple occasions (156.6 +/- 144.8 microg/ml versus 70.9 +/- 92.3 microg/ml; P = 0.001). These data suggest that the protective effects of human milk against ARI may be due in part to immune maturation effects by secreted 90K.

Acute Disease↗

PubMed1998

Increased levels of soluble P-selectin in hypercholesterolemic patients.

BACKGROUND: Hypercholesterolemia is considered a major risk factor for the development of atherosclerosis. Enhanced lipid peroxidation and persistent platelet activation can be observed in vivo in hypercholesterolemic patients and may have pathophysiological implications in the occurrence of cardiovascular events. P-selectin may play an important role in the pathogenesis of multicellular events, including atherosclerosis. We studied the impact of hypercholesterolemia and oxidative stress on plasma levels of P-selectin. METHODS AND RESULTS: Plasma levels of P-selectin were measured by means of an enzyme immunoassay in 20 hypercholesterolemic patients with no clinical evidence of cardiovascular disease and in 20 sex- and age-matched normocholesterolemic subjects. Hypercholesterolemic patients had higher levels of P-selectin compared with that of control subjects (98+/-61 versus 56+/-14 ng/mL; P=.001). They also displayed increased von Willebrand Factor (vWF) levels (176+/-22 versus 119+/-12%; P=.0001). A direct correlation was observed between P-selectin and LDL cholesterol levels (p=.453). Administration of vitamin E (600 mg/d for 2 weeks) to hypercholesterolemic patients significantly reduced plasma P-selectin (40%), and an inverse correlation was observed between vitamin E and P-selectin plasma levels (p=-.446). CONCLUSIONS: Hypercholesterolemia is associated with elevated plasmatic P-selectin. Altered oxidative processes leading to endothelial dysfunction and persistent platelet activation may contribute to increased soluble P-selectin levels. P-selectin may be proposed as a marker of endothelial dysfunction in hypercholesterolemic patients.

Cholesterol, LDL↗

PubMed1998

90K (MAC-2 BP) gene expression in breast cancer and evidence for the production of 90K by peripheral-blood mononuclear cells.

The tumor-derived antigen 90K (Mac-2 BP) is a widely expressed, secreted glycoprotein found in the serum of healthy individuals and at elevated levels in the serum of patients with breast cancer and other types of cancer. The precise function of 90K, particularly in the context of tumor-host relationships, has not yet been established. In this study, the clinical significance of 90K mRNA expression was studied in relation to other established prognostic parameters in 86 patients with primary breast carcinoma. The 2.2-kb 90K message was detected in all tumor samples, but there was marked variation in expression levels from tumor to tumor. Patients were classified into 2 groups on the basis of 90K expression: group 1 (n = 62) included patients with low expression, and group 2 (n = 24) consisted of patients with high expression. An inverse significant correlation was found between the levels of 90K mRNA expression and overexpression of c-erbB2/Neu receptor kinase, a marker of poor prognosis for patients with breast cancer. There was no significant difference between the groups with respect to tumor size, number of involved axillary lymph nodes, hormone-receptor status, p53 expression or proliferation activity as estimated by Ki-67 count. Similarly, no association was found between the level of 90K expression and the risk of death from breast cancer. These data are at variance with published findings showing that high serum 90K levels are associated with poor survival. Significantly, investigation of 90K-gene expression in peripheral-blood mononuclear cells (PBMC) revealed higher levels of 90K message in PBMC of breast-cancer patients than in healthy individuals. This new finding suggests that PBMC activated in response to tumor growth and progression may be an important source of serum 90K in breast cancer.

Adult↗

PubMed1998

Differential effect on TCR:CD3 stimulation of a 90-kD glycoprotein (gp90/Mac-2BP), a member of the scavenger receptor cysteine-rich domain protein family.

We studied the effects of a 90-kD glycoprotein (gp90/Mac-2BP) belonging to the scavenger receptor family, present in normal serum and at increased levels in inflammatory disease and cancer patients, on some T cell function parameters. Whereas the lymphocyte proliferative response to non-specific mitogens such as phytohaemagglutinin (PHA) and concanavalin A (Con A), but not pokeweed mitogen (PWM), was strongly reduced, probably due to the lectin-binding properties of gp90/Mac-2BP, the response to T cell receptor (TCR) agonists such as superantigens and allogeneic cells was potentiated. When lymphocytes were stimulated with different anti-TCR:CD3 MoAbs, both in soluble and solid-phase form, gp90/Mac-2BP was able to down-regulate the proliferative response to anti-CD3 MoAb, whereas the response to anti-TCR alphabeta MoAb was enhanced. A similar differential effect was observed when a MoAb against CD5 (another member of the scavenger receptor superfamily) was added to anti-CD3 or anti-TCR-stimulated cells; anti-CD5 MoAb strongly down-modulated the CD3-mediated response, whereas its presence in culture was associated with potentiation of the response to TCR alphabeta agonists. gp90/Mac-2BP was able per se to up-regulate Ca2+ levels in freshly isolated lymphocytes; moreover, its presence in culture was associated with increased Ca2+ mobilization following stimulation with anti-TCR alphabeta, but not anti-CD3 MoAb. These data indicate that gp90/Mac-2BP could be able to influence some immune responses, possibly through multiple homologous interactions with other members of the scavenger receptor family; moreover, our findings suggest that signalling through the different components of the TCR:CD3 complex may follow distinct activation pathways into the cells.

3T3 Cells↗

PubMed1998

90K (Mac-2 BP) predicts CD4 decline in human immunodeficiency virus-infected patients with CD4 counts above 200 x 10(6) cells/L.

OBJECTIVE: To evaluate the ability of serum levels of 90K, previously reported as a progression marker of human immunodeficiency virus infection, to predict the future rate of CD4 lymphocyte decline. DESIGN: Retrospective analysis of data from outpatients enrolled in a multi-institutional study. PATIENTS: One hundred five human immunodeficiency virus-positive intravenous drug users who had at least six serial CD4 lymphocyte measurements and starting CD4 levels of 200 x 10(6) cells/L or higher. MAIN OUTCOME MEASURE: Rate of CD4 lymphocyte decline. RESULTS: During a median follow-up of 28 months (range, 20-36 months), the estimated loss of CD4 cells in the whole patient population was 3.4 x 106 cells/L per month (P = .0045). Subjects who were on zidovudine treatment at study entry showed an average loss of 3.8 x 10(6) cells/L per month, significantly higher than in untreated subjects (P = .02), but similar to the loss observed for those requiring initiation of treatment during the course of the study. At baseline, 56 subjects had 90K levels of 10 microg/mL or less, and 49 had more than 10 microg/mL. The rate of CD4 decline in the high-90K group was approximately 5 x 10(6) cells/L per month (P < .0015), whereas in the low-90K group it was not different from zero (P = ns). No difference emerged in the rate of CD4 decline when subjects were stratified according to baseline 90K levels and zidovudine treatment, beta2-microglobulin, or neopterin serum levels. CONCLUSION: 90K serum levels are predictive of CD4 decline.

Antigens, Neoplasm↗

PubMed1997

Identification of the tumor antigen 90K domains recognized by monoclonal antibodies SP2 and L3 and preparation and characterization of novel anti-90K monoclonal antibodies.

The tumor antigen 90K (Mac-2BP, L3 antigen), which has been shown to have T cell costimulatory activity, is a approximately 90 kDa secreted protein found in high levels in plasma, saliva, breast milk and other human fluids. The 90K antigen can be divided into three domains: an amino terminal scavenger receptor cysteine-rich (SRCR)-like domain (D1), followed by a heavily glycosylated mucin-like domain (D2) and a approximately 27 kDa carboxy-terminal domain (D3). In this study we report on the construction of six different 90K immunoglobulin (Ig) fusion proteins containing different 90K domain combinations. Initially these fusion proteins were used to identify which 90K domain contains the epitopes recognized by the anti-90K monoclonal antibodies (mAb) SP2 and L3. Both of these mAbs were found to recognize 90K-D2. A new panel of anti-90K mAb was then generated by immunizing mice with ascites derived 90K protein. The 90K domain specific fusion proteins were then used to identify novel anti-90K mAbs which recognize the amino terminal SRCR domain and the carboxy terminal approximately 27 kDa domain of 90K. Two novel anti-90K SRCR (D1) and one anti-90 27 kDa domain (D3) mAbs were obtained. These 90K-Ig fusion proteins, as well as the novel and existing anti-90K mAbs, provide a set of tools which will allow further dissection of the structure and function of this immune modulatory protein.

Antibodies, Monoclonal↗

PubMed1997

Expression of the 90K immunostimulator gene is controlled by a promoter with unique features.

90K is a secreted glycoprotein with tumor suppressive functions, which is up-regulated in various types of cancer and in AIDS. In order to understand the regulation of its expression, the mouse 90K gene was isolated and analyzed. The gene spans about 8.8-kilobase pairs and consists of 6 exons and was localized on chromosome 11, region E. RNase protection identified one major transcription start site (+1) and three minor ones (-3, +32, +34). The mouse 90K gene was found to have a TATA-less promoter of unusual structure. The 2. 3-kilobase pair 5'-flanking region exhibited strong promoter activity in NIH 3T3 cells; however, it contained neither a TATA-box nor a SP1 site and was not GC-rich. No known initiator motif was found around the transcription start site. 5'- and 3'-deletions defined a minimal promoter of 51 base pairs (-66 --> -16), not including the start site, essential and sufficient for promoter activity. This minimal promoter showed increased activity after stimulation with interferon-gamma or poly(I.C), a substance mimicking viral infection. Essential for both inductions was the integrity of an interferon regulatory factor element within this sequence, a potential binding site for the anti-oncogenic transcription factor interferon regulatory factor-1.

3T3 Cells↗