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S Soddu

Publications and source records attributed to S Soddu.

53 records · Page 3Linked to original sources
PubMed1995

Retinoic acid and cAMP differentially regulate human chromogranin A promoter activity during differentiation of neuroblastoma cells.

We report the first evidence that differential transcriptional regulation of human chromogranin A (CHGA) gene expression occurs during in vitro treatment of tumorigenic neuroblastoma (NB) cells with retinoic acid (5 microM) and/or dibutyryl-cAMP (1 mM). The CHGA gene encodes a tissue specific protein restricted to cells of the diffuse neuroendocrine system, but also widely expressed among NB tumours. We previously reported that CHGA as well as other neuroendocrine markers are modulated during NB differentiation in vitro. To investigate, at the molecular level, the mechanisms leading to NB tumour cell differentiation during the treatment with biologically active compounds, we sequenced and functionally characterised 2169 bp of a genomic DNA clone encompassing the 5' flanking region of the human CHGA gene. Computer-assisted analysis of the sequence revealed the presence of a cAMP responsive element at positions -56 to -49, and Sp1 binding sites at positions -181 to -176 and -216 to -210. Two novel 9 bp motifs, located at position -462 to -454 and -91 to -83 of the CHGA promoter were identified in the regulatory regions of two other neuroendocrine genes encoding for tyrosine hydroxylase and neuropeptide Y. In addition, in the first 1000 bp of the untranslated 5' region, we found the presence of several putative DNA binding sites of bHLH molecules, a protein family regulating tissue specific differentiation. Transient transfection experiments of chloramphenicol acetyltransferase (CAT) deletion constructs, showed the presence of an active promoter within the first 455 bp upstream from the start site. This region conferred tissue specific expression to a CAT reporter gene. In addition, the transcriptional activity of this fragment was modulated during the induction of differentiation of NB cells treated by retinoic acid and/or dibutyryl-cAMP. These observations provide preliminary data regarding CHGA transcriptional regulation in NB cells, and indicate that retinoic acid and cAMP activate distinct, apparently competitive, transcriptional pathways during NB cell differentiation. The molecular characterisation of the mechanisms regulating CHGA expression in tumour and normal neuroendocrine tissue could lead to the identification of novel molecules potentially relevant for future gene therapy of NB tumours.

Base Sequence↗
PubMed1994

Wild-type p53 gene expression induces granulocytic differentiation of HL-60 cells.

Overexpression of wild-type p53 gene in malignant cell lines has been shown to inhibit cell proliferation in a number of cases. However, endogenous p53 protein seems to play little role in normal cell-cycle control as suggested by the normal development of p53 null mice, and by the low p53 protein levels expressed in most cell types. Recently, increased expression of endogenous p53 protein has been observed during the cellular response to DNA damage, as well as during differentiation of human hematopoietic cells. To study the role of the p53 gene in hematopoietic differentiation, we introduced the wild-type p53 gene or the temperature-sensitive p53(Val135) mutant into p53-deficient HL-60 promyelocytic leukemia cells. Morphological analysis, flow-cytometric determination of granulocytic or monocytic surface markers, and ability to reduce nitroblue tetrazolium (NBT) demonstrated that expression of exogenous wild-type p53 gene in HL-60 cells induces differentiation through the granulocytic pathway. Proliferation and cell-cycle analysis performed early after expression of wild-type p53 showed that induction of differentiation is not coupled with growth arrest, which suggests that p53 is involved in differentiation independently of its activity on the cell cycle.

Base Sequence↗
PubMed1993

Wild-type p53 differentially affects tumorigenic and metastatic potential of murine metastatic cell variants.

The structure and the function of the p53 gene were studied in two metastatic cell variants derived from Lewis lung carcinoma. Single missense mutation at codon 334 was detected in the p53 gene of both cell variants. In spite of the identical mutation, the in vitro and in vivo growth rates of the two cell variants were differentially affected by the constitutive expression of exogenous wild-type (wt) p53 gene. In fact, only the more malignant cell line (C87) was severely affected by the wt-p53 gene introduction. However, the in vivo effects on this cell line were transient because during serial in vivo passages, cell populations lacking the wt-p53 gene were selected. Genetic mechanisms responsible for the resistance of the less metastatic cell variant (BC215) to the wt-p53 expression, were investigated. Intrinsic ability to mutate exogenous cDNA sequences was tested. We report that BC215 cells continued to express exogenous wt-p53 sequences after several in vitro passages. The expression of mdm2 gene was evaluated. The data demonstrated that BC215 cells constitutively express higher levels of mdm2 gene than C87 cells. We conclude that the overexpression of this gene might be responsible for the resistance of BC215 cells to exogenous wt-p53 gene expression.

Animals↗
PubMed1992

Driving adenovirus type 12-transformed BALB/c mouse cells to express high levels of class I major histocompatibility complex proteins enhances, rather than abrogates, their tumorigenicity.

The tumorigenicity of adenovirus type 12 (Ad12)-transformed cells has been attributed to the low levels of class I major histocompatibility complex (MHC) protein expression by these cells. These levels of class I proteins are thought to be below the threshold critical for cytotoxic T-lymphocyte recognition, a process that may be involved in tumor cell immunosurveillance. We have used gene transfer experiments to investigate the role played by class I protein expression in the tumorigenicity of Ad12-transformed BALB/c mouse cells in naive, syngeneic adult mice. Our Ad12-transformed mouse cells were tumorigenic in adult mice and were similar to other Ad12-transformed mammalian cells in that they expressed low levels of class I MHC mRNA and cell surface proteins. Despite these low levels of expression, the cells were highly immunogenic in syngeneic mice and were rejected as allografts by allogeneic mice. Transfection of genomic H-2Dd or H-2Ld fragments into these cells produced a variety of cell clones that expressed increased levels of cell surface class I proteins. These cells expressing high levels of class I protein were up to 16-fold more tumorigenic than the parental cells in syngeneic adult mice. Thus, by quantitative assays, the tumorigenicity of Ad12-transformed BALB/c mouse cells is not functionally related to the low levels of class I MHC proteins they express. The increased tumorigenicity expressed by H-2Dd- and H-2Ld-transfected cells was not detected in BALB/c nu/nu mice, suggesting that a thymus-dependent mechanism that is not mediated by evasion of cytotoxic T-lymphocyte recognition could contribute to the difference in tumorigenicity of Ad12-transformed BALB/c mouse cells that express low and high levels of class I MHC proteins.

Adenoviridae Infections↗
PubMed1991

Suicide behavior of target cells after binding with natural killer cells.

Human natural killer (NK) cell activity seems to be related to the integrity and function of the cytoskeletal apparatus. It has been hypothesized that microfilaments and microtubules play a pivotal role. In particular, the binding of the NK cell to the target cell requires microfilament integrity, and the lysis of bound targets seems to depend on microtubule assembly. We focused on the changes occurring in cytoskeletal elements and surface structures of NK cells and of target cells highly sensitive to NK activity (K562). Our observations, performed by fluorescence and scanning electron microscopy, besides confirming a rearrangement of the cytoskeletal apparatus in the effector cell, provide evidence that target cell cytoskeletal elements are involved in NK cell function. In K562 cells, after binding with NK cells, there is marginal rearrangement of actin and polarization of tubulin and vimentin in the contact regions, accompanied by modification of surface structures. These findings suggest that the target cell plays an active role in its own death by participating in the formation of an extended area of intimate contact with the killer cell. In addition, they lend credence to the surprising proposal that NK cells may induce a suicide mechanism in target cells.

Cell Survival↗
PubMed1988

Mechanism of defective natural killer cell activity in patients with AIDS is associated with defective distribution of tubulin.

Previous studies have demonstrated the importance of some cytoskeleton components in killing mechanisms. In fact, a microtubule and microfilament (MF) rearrangement in the lytic sequence of CTL and NK cells has been observed. In particular, MF seem to be related to the binding phase, because MF inhibitors suppress the binding of NK cells to the target, whereas microtubule inhibitors suppress only the killing phase. In this paper, the distribution of two cytoskeleton components, actin and alpha- and beta-tubulin, has been studied in PBL from AIDS patients, who maintain the capacity to bind to the target cell line K562 but are not able to kill it. PBL were labeled with mAb to these two cytoskeleton components, and then indirect immunofluorescence was used to visualize their distribution in the conjugates. A normal polarization of actin in the effector PBL was found, whereas no tubulin rearrangement was evident in the effector and target cells. On the contrary, in conjugates of PBL or large granular lymphocytes from normal donors and K562, a polarization of actin in the effector cell and a polarization of tubulin both in the effector and in the target cells, at the site of the attachment, was evident. These data suggest that a deficiency of tubulin rearrangement may underlie the inability of the NK cells from AIDS patients to kill their target.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Natural killer activity from normal peripheral blood lymphocytes against a human T lymphotropic retrovirus type III (HTLV-III)-infected cell line.

An H9-HTLV-III-infected cell line was used as a target in a short-term (3-hr) Cr release assay to assess its sensitivity to lysis by peripheral blood lymphocytes (PBL) from normal donors. The single cell cytotoxicity assay (SCCA) on poly-L-lysine-coated coverslips was used to investigate further the mechanism of binding and killing. Uninfected H9 and K562 cell lines were studied as controls. Our results argue in favour of a natural killer (NK) mechanism being operative on an H9-HTLV-III-infected cell line owing to the following findings: (1) the cell line is sensitive to lysis in a short-term assay; (2) its sensitivity is significantly higher than K562; and (3) the kinetics of lysis, as assessed by SCCA, is similar to that of K562, with a more efficient killing being detectable against H9-HTLV-III. Furthermore, a phenotypic analysis of effector cells suggests that CD4+ lymphocytes are also involved in the lysis of this target. Our data provide evidence for an immune mechanism that may be operative in HTLV-III infection. We then studied, by this method, five groups of patients: one (n = 20) affected by acquired immunodeficiency syndrome (AIDS), one (n = 20) by AIDS-related complex (ARC), one (n = 20) by lymphadenopathy syndrome (LAS), one group (n = 40) of HTLV-III seropositive, apparently healthy people, and one (n = 40) of healthy HTLV-III seronegatives.(ABSTRACT TRUNCATED AT 250 WORDS)

AIDS-Related Complex↗
PubMed1987

Immune response to cytomegalovirus in patients with acquired-immunodeficiency syndrome related complex (ARC) and AIDS.

This study was undertaken with the aim of elucidating the mechanisms underlying the cell-mediated immunodeficiency seen in the acquired immunodeficiency syndrome (AIDS). An intrinsic functional defect in the in vitro surviving T lymphocytes from patients with AIDS has been described. This defect is reflected by profound reductions in both the cloning efficiency of these cells and in the number of precursor cells for response to lectins. Since many patients affected by AIDS present active cytomegalovirus (CMV) infections and impairment in CMV-specific cellular immunity, we examined the number of CMV-specific precursor cells in patients affected by the AIDS-related complex (ARC), who had serum antibodies to CMV and to the human-T-lymphotropic retrovirus-type III (HTLV-III), recently termed human immunodeficiency virus (HIV). Their responses were compared to those of patients with AIDS and to those of healthy-CMV-seropositive and HTLV-III seronegative controls. We detected a significant reduction of precursors for cell-mediated immune response to CMV in AIDS, in comparison to normal controls and a reduction in ARC, even if not significant. In parallel, we assayed the response to phytohemagglutinin, which was maintained in ARC and depressed in AIDS. Our results show a defect of specific cell-mediated immunity to CMV in ARC and AIDS patients.

AIDS-Related Complex↗
PubMed1986

Recurrent herpes genitalis, severe impairment of specific cell-mediated immune response and bilateral femoral head necrosis: report of a case.

The case of a 56 years old patient, affected by recurrent herpes genitalis (RHG) is reported. The patient came to our observation on March 1983 and he was suffering from RHG for 20 years, before our study. Episodes of RHG were severe, due to local and general symptomatology. Characterization of immune response showed decrease of NK activity to the K562 cell line, impairment of specific cell mediated immunity to Herpes simplex virus (HSV) as well as a decrease of T cells with helper phenotype. HSV type 2 was stained from active lesions. Immunological alterations were present irrespective of phase of activity of the disease during all the follow up period (March 1983-March 1985). At the first visit the patient was found to be suffering from a femoral head necrosis (FHN) of the right leg. One year later the same disease appeared at the contralateral leg. The possible relationship between RHG, accompanied by the described immunodeficiency, and the FHN is described.

Femur Head↗
PubMed1986

Evidence for disregulation in the control of Epstein-Barr virus latency in patients with AIDS-related complex.

Patients affected by AIDS-related complex (ARC) show several immunological abnormalities which may lead to a disregulation of immunosurveillance against viral latent infections. In this paper evidence for Epstein-Barr virus (EBV) reactivation in seven out of eight affected by persistent generalized lymphadenopathy is given. These patients showed either elevated levels of circulating EBNA-positive transformed cells or depressed EBV-specific T cell cytotoxicity, as assessed by the regression assay, or both. A direct involvement of EBV in the pathogenesis of ARC is thus suggested. Natural killer cell activity was found decreased, correlating to the evidence of circulating EBV-infected cells and of impaired EBV-specific immune control. These data provide evidence that, when specific immune mechanisms lose control on ubiquitous latent viruses, the risk for reactivation becomes higher. In the case of EBV, direct evidence of this event is provided by the emergence in the peripheral blood of clones of infected cells with unlimited growth potential.

AIDS-Related Complex↗
PubMed1986

Immunological responses of patients with recurrent herpes genitalis.

Immunological responses of patients with recurrent herpes genitalis (RHG) were assayed in comparison to those of patients affected by recurrent herpes labialis (RHL) and to those of normal seropositive and seronegative controls. Total T cells were normal while a significant (p less than 0.001) reduction of cells with helper phenotype was found only in people with RHG, who were also lacking specific cell-mediated immunity (CMI) to herpes simplex virus (HSV) antigen. HSV-type 2 was demonstrated in their active lesions. Number of human NK-1 positive (HNK-1 +) cells was increased in RHG showing an inverse correlation with depressed natural killer (NK) activity. These abnormalities were found irrespective or not if tests were carried out during the active phase of the disease or during quiescence and were confirmed during the 2-year follow-up period to which patients were submitted. Similar abnormalities were found in RHL only during the active phase and reversed to normal during quiescence. Our data indicate the presence of specific cellular and NK unresponsiveness in subjects with severe and long-lasting herpes genitalis.

Adolescent↗
PubMed1986

House mite dust bronchial asthma: clinical and epidemiological observations.

The incidence of respiratory allergy in an adult population from Lazio is reported. A high prevalence rate of bronchial asthma was found, whereas the evolution of allergic rhinitis into bronchial asthma was less pronounced than that reported for childhood allergy. The mean age of onset of the symptoms was 15 +/- 5 years. A remarkable number of patients suffered from oculorhinitis, which resulted in bronchial asthma in a mean time of 5 +/- 3 years. Most of the patients came from Rome and were low-middle class. Previous history of possible co-factors in the development of respiratory allergies showed a high percentage of family atopy and of asthmatiform bronchitis. Studies of allergens responsible for disease revealed that house mite dust and Dermatophagoides are the major allergens responsible for the symptoms. An analysis of the most common therapy used for treating patients demonstrated a prevalence of anti-histamine, DSCG and chetotifen whereas cortisone treatment and hospitalization were less overspread. The present epidemiological survey shows a prevalence of adult onset bronchial asthma due to house mite dust. The importance of this observation in preventive medicine programmes is discussed.

Asthma↗
PubMedDate not supplied

Exogenous wt-p53 protein is active in transformed cells but not in their non-transformed counterparts: implications for cancer gene therapy without tumor targeting.

BACKGROUND: Expression of exogenous wild-type p53 (wt-p53) protein in tumor cells can suppress the transformed phenotype whereas it does not apparently induce detrimental effects in non-transformed cells. This observation may provide a molecular basis for p53-mediated gene therapy of p53-sensitive cancers without the need for tumor targeting. METHODS: To understand the molecular mechanisms responsible for this different behavior in tumor versus normal cells, biochemical and functional analyses of exogenous wt-p53 protein were performed on non-transformed C2C12 myoblasts and their transformed counterparts, the C2-ras cells. RESULTS: The exogenous wt-p53 protein, which induced persistent growth arrest only in transformed C2-ras cells, was shown to be significantly more stable in transformed than in non-transformed cells. This different stability was due to different p53 proteolytic degradation. Moreover, constitutively, exogenous wt-p53 protein was found to be transcriptionally active only in C2-ras cells but it could also be activated in C2C12 cells by genotoxic damage. CONCLUSIONS: Non-transformed C2C12 cells present regulatory system(s) which control the expression and the activity of exogenously expressed wt-p53 protein probably through degradation and maintenance in a latent form. This regulatory system is lost/inactivated upon transformation.

Adenoviridae↗
PubMedDate not supplied

Activation of p53/p21waf1 pathway is associated with senescence during v-Ha-ras transformation of immortal C2C12 myoblasts.

It has recently been shown that tumor cells can retain the ability to undergo senescence, while the capacity of bypassing senescence has been associated with tumor progression. In this report, we showed that v-Ha-ras-mediated transformation of already immortal C2C12 myoblasts can be associated with senesence, in a low amount during in vitro passages and, to a higher extent, affer cellular stress (cell culture alkalinkation), or DNA damage (doxorubicin treatment). The capacity to undergo replicative senescence is associated with a strong increase of wt-p53 transcriptional activity and p21WAF1 up-regulation. These biochemical activities are down-modulated in the cells that evade the massive replicative senescence after stressing stimuli. Altogether, these findings show that active ras can cause senescence during the transformation of already immortal cells in associaton with p53/p21WAF1 pathway activation and support the hypothesis that p53/p21WAF1 functional activity is important in maintaining the integrity of the senescence pathway during cellular transformation.

Animals↗
PubMedDate not supplied

[p53: prospects for gene therapy of cancer].

PURPOSE: To evaluate the prospects for cancer gene therapy through restoration of wild-type p53 (wt-p53) protein expression and/or function. DESIGN: To review the most significant data reported in the literature with particular attention in dissecting the biological questions that are still open and need to be clarified to improve TP53-based gene therapy. RESULTS: Considerable experimental evidence obtained in vitro and in vivo indicates that wt-p53 protein can suppress the transformed phenotype of several types of cancer in humans as well as other species. Wt-p53 protein suppress transformation by inducing different biological effects including maintenance of genomic stability, inhibition of cell proliferation, induction of apoptosis, differentiation or senescence. All these findings have rendered p53 a potential helpful target for therapy of many types of human cancers. CONCLUSIONS: Different experimental strategies based on i) TP53 gene-replacement, ii) restoration of wt-p53 activity, iii) replication of defective lytic viruses specifically in altered p53-expressing tumors, have given promising results in vitro and, in some cases also in vivo. At present, a few phase one clinical trials have been started for some of the gene-replacement strategies.

Apoptosis↗