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A Iavarone

Publications and source records attributed to A Iavarone.

At least 37 records · Page 2Linked to original sources
PubMed1996

Id2 specifically alters regulation of the cell cycle by tumor suppressor proteins.

Cells which are highly proliferative typically lack expression of differentiated, lineage-specific characteristics. Id2, a member of the helix-loop-helix (HLH) protein family known to inhibit cell differentiation, binds to the retinoblastoma protein (pRb) and abolishes its growth-suppressing activity. We found that Id2 but not Id1 or Id3 was able to bind in vitro not only pRb but also the related proteins p107 and p130. Also, an association between Id2 and p107 or p130 was observed in vivo in transiently transfected Saos-2 cells. In agreement with these results, expression of Id1 or Id3 did not affect the block of cell cycle progression mediated by pRb. Conversely, expression of Id2 specifically reversed the cell cycle arrest induced by each of the three members of the pRb family. Furthermore, the growth-suppressive activities of cyclin-dependent kinase inhibitors p16 and p21 were efficiently antagonized by high levels of Id2 but not by Id1 Id3. Consistent with the role of p16 as a selective inhibitor of pRb and pRb-related protein kinase activity, p16-imposed cell cycle arrest was completely abolished by Id2. Only a partial reversal of p21-induced growth suppression was observed, which correlated with the presence of a functional pRb. We also documented decreased levels of cyclin D1 protein and mRNA and the loss of cyclin D1-cdk4 complexes in cells constitutively expressing Id2. These data provide evidence for important Id2-mediated alterations in cell cycle components normally involved in the regulatory events of cell cycle progression, and they highlight a specific role for Id2 as an antagonist of multiple tumor suppressor proteins.

Cell Cycle↗
PubMed1995

Differentiation of neuroblastoma enhances Bcl-2 expression and induces alterations of apoptosis and drug resistance.

Recent evidence suggests that resistance to antineoplastic therapy may result from mutations in genes mediating the apoptotic response to DNA damage. To determine the effects of epigenetic changes on tumor responsiveness to cytotoxic agents inducing DNA damage, we examined the chemosensitivity of neuroblastoma (NB) after differentiation by retinoic acid (RA). Differentiation of the cell lines SH-SY5Y and SMS-KCNR by RA abolished the cytotoxic effects of adriamycin (Adr) and cisplatin. Chemoresistance was not the result of decreased proliferation induced by RA because: (a) growth arrest by nutrient deprivation did not affect sensitivity; (b) growth arrested NB cell lines, which did not differentiate, remained chemosensitive; and (c) RA concentrations which promoted differentiation without affecting growth, induced resistance. Apoptosis characterized NB cells responding to Adr, although differentiated SH-SY5Y did not apoptose and were resistant to Adr and cisplatin. Marked induction of bcl-2 in NB cells followed RA-induced differentiation, whereas in cell lines failing to differentiate, bcl-2 was not detected. Our data indicate that NB differentiation induces drug resistance after a loss of the apoptotic response to antineoplastic drugs and suggest that bcl-2 overexpression is an important mechanism of resistance in differentiated tumor cells.

Apoptosis↗
PubMed1995

Kip/Cip and Ink4 Cdk inhibitors cooperate to induce cell cycle arrest in response to TGF-beta.

G1 progression in mammalian cells requires the activity of the cyclin D-dependent kinases Cdk4 and/or Cdk6 and the cyclin E-dependent kinase Cdk2. Proliferating Mv1Lu mink lung epithelial cells and human keratinocytes contain high levels of the universal Cdk inhibitor p27Kip1 distributed in complexes with Cdk2, Cdk4, and Cdk6. Addition of the antimitogenic cytokine transforming growth factor-beta (TGF-beta) elevates expression of the Cdk4/6-specific inhibitor p15Ink4B and induces the release of p27 from Cdk4 and Cdk6. In Mv1Lu cells, this release of p27 coincides with increased binding of p27 to Cdk2. Recombinant p15 inhibits p27 binding to Cdk4 in vitro, and p15 overexpression induces the transfer of p27 from Cdk4 to Cdk2 in vivo, suggesting that the release of Cdk4-bound p27 in TGF-beta-treated cells is caused by the surge in p15 levels. In keratinocytes, TGF-beta increases not only p15 but also p21Cip1, which binds to Cdk2. These events correlate with Cdk2 inhibition and cell cycle arrest and occur without a loss of G1 Cdk components. The results suggest that TGF-beta induces G1 arrest in these two epithelial cell types by inhibiting various cyclin-Cdk kinases through the cooperative action of an Ink4 Cdk inhibitor and a Cip/Kip Cdk inhibitor. Subsequent to cell cycle arrest, Cdk2 and Cdk4 levels decline as part of a second set of events that may represent a program of cell adaptation to the quiescent state.

Animals↗
PubMed1995

Constitutional p53 mutations associated with brain tumors in young adults.

Identification of patients at risk for developing brain tumors is important for the development of preventative strategies. Because individuals with germline p53 mutations may be at increased risk, we examined DNA from brain tumor-derived cell lines and malignant and normal nervous system tissue for p53 gene mutations using the single strand conformation polymorphism assay and direct sequencing of polymerase chain reaction-amplified DNA. We found mutations in the p53 gene in eight of 22 adult glioma tissue specimens and germline mutations in two of these eight patients. In contrast, mutation of the p53 gene was not detectable in either 16 glial tumors occurring in children, glial tumor tissue from three unrelated glioblastoma multiforme patients with a familial history of cancer, or in benign meningiomas. One constitutional p53 mutation was a G to T transversion at codon 154, and the second was a C to T transition at codon 256. Both patients with germline mutations developed glioblastoma multiforme before the age of 31, although the median age for glioma patients is above 50. These findings suggest that p53 germline mutations may identify a subset of young adults predisposed to the development of high-grade astrocytic tumors.

Adult↗
PubMed1995

Carboplatin in childhood medulloblastoma/PNET: feasibility of an in vivo sensitivity test in an "up-front" study.

Sixteen patients with high risk MB/PNET at diagnosis were included in a pilot study employing carboplatin (CBDCA) as a single drug prior to conventional therapy. The main goal of the study was to identify in a short-term trial a significant response that would predict further response to CBDCA in the single patient. Exploration of CBDCA activity was focused on response after the first course as compared to the response following the second course. A course consisted of CBDCA 600 mg/m2 on days 1 and 2 administered in a 1 h infusion to be repeated 3-4 weeks later. After two cycles we observed 1 CR and 9 PR, that is a 62% response rate. The first course resulted in 5 PR, 5 MR, 5 SD, and 1 PD; after the subsequent course in all responding patients, response persisted or improved whereas in no patient with SD any improvement was observed. The correlation of response to the first course with response to the second course was statistically significant (P = 0.0009). The main toxicity of the single course was hematologic and consisted of rapidly reversible grade 3-4 neutropenia and thrombocytopenia in 94% of patients. Pharmacokinetic studies showed a very limited interpatient variability of both Cmax 57.6 +/- 9.9 micrograms/ml) and AUC (15.3 +/- 1.5 mg/ml.min) of free CBDCA, which eliminates an important variable in the evaluation of response. In conclusion, this "in vivo test" appears effective, reasonably safe, and reproducible in identifying patients likely to benefit from CBCDA: after a period of time as short as 3-4 weeks following the first course, multidrug chemotherapy including CBDCA may be employed in the responding patients, whereas an alternative regimen would be indicated in the non-responding patients.

Adolescent↗
PubMed1995

Anosognosia, intrusions and 'frontal' functions in Alzheimer's disease and depression.

The relationship between anosognosia of memory deficit, intrusions and 'frontal' functions was investigated in 12 Alzheimer (DAT) patients, 12 depressed patients and 24 normal controls. DAT and depressed patients could not be dissociated according to the proportion of intrusion they produced in memory tasks. However, regardless of their clinical diagnosis, patients with anosognosia produced significantly more intrusions than patients without anosognosia, and anosognosia of memory deficit was positively and strongly correlated to the tendency to produce intrusions. By contrast, there was no correlation between intrusions, anosognosia and patients' performance on frontal tasks except for Verbal Fluency. Whereas anosognosia of memory deficit seems indispensable for intrusions, frontal dysfunction must not be considered a necessary condition for intrusions or anosognosia.

Age Factors↗
PubMed1995

Release mechanisms of [125I]meta-iodobenzylguanidine in neuroblastoma cells: evidence of a carrier-mediated efflux.

[131I]metaiodobenzylguanidine ([131I]MIBG) is selectively taken up and stored by tumours derived from the neural crest, and is used for diagnosis and treatment of neuroblastoma (NB). The antitumoral effect of [131I]MIBG is closely related to the intracellular level of the radiopharmaceutical compound, which is dependent on uptake and storage/release mechanisms. While MIBG uptake is well characterised, storage and release mechanisms are still controversial. In order to better characterise [125I]MIBG release mechanisms, we studied the basal and stimulated efflux of [125I]MIBG in the human NB cell line, SH-SY5Y, preloaded with 0.1 microM [125I]MIBG for 1 h. We found that [125I]MIBG basal efflux is highly temperature-dependent, that [125I]MIBG release, induced by cell depolarisation with high potassium, is mainly calcium-independent, and induced by exchange with cold MIBG or noradrenaline, inversion of the sodium gradient across the cell membrane by veratridine by substitution of sodium chloride with equimolar concentration of lithium chloride. The exposure of NB cells to imipramine, an Uptake-1 inhibitor, also produces a net stimulatory effect on [125I]MIBG release. However, when used in association with other releasing stimuli, such as higher levels of intracellular sodium or external agonists, imipramine abolishes the consequent increase of [125I]MIBG release. Our findings suggest that stimulated [125I]MIBG release is mediated by a carrier, most probably the uptake carrier working in a reverse mode, while a minimal fraction of [125I]MIBG is released by an exocytotic mechanism.

3-Iodobenzylguanidine↗
PubMed1995

HLA-haploidentical umbilical cord blood stem cell transplantation in a child with advanced leukemia: clinical outcome and analysis of hematopoietic recovery.

Growing attention has been focused on cord blood as a source of transplantable hematopoietic stem cells. However, clinical experience is rather limited. In this study we describe a child with advanced acute lymphoblastic leukemia who received an HLA-haploidentical cord blood transplant. The patient was transplanted in third complete remission after conditioning with fractionated total body irradiation, thiotepa and cyclophosphamide. Forty-one milliliters of cryopreserved umbilical cord blood, containing 0.15 x 10(8) nucleated cells/kg and 0.25 x 10(4) CFU-GM/kg, were infused. Cyclosporine and prednisone were administered for graft-versus-host disease (GVHD) prophylaxis. The patient received G-CSF from day +1 to day +35, but no improvement in granulocyte counts was observed. Therefore, administration of GM-CSF was started on day +36 to day +59, which resulted in a significant increase in white blood cells and granulocyte counts. Sustained myeloid engraftment was evidenced by a granulocyte count > 0.5 x 10(9)/l by day +41. The presence of donor-derived cells could be documented in the peripheral blood and bone marrow of the patient by cytogenetic analysis, HLA phenotyping and DNA studies. Forty-one days after transplant, clonogenic bone marrow assays showed the presence of low frequencies of primitive hematopoietic progenitor cells (BFU-E = 19/10(5) and CFU-GM = 8/10(5)). The chimerism was complete and no host-derived cells could be detected. However, the engraftment was restricted to the myeloid lineage whereas lymphoid and megakaryocytic engraftments were inadequate. The immunophenotype of the patient's peripheral blood showed the presence of T lymphocytes expressing an immature phenotype (CD2+ CD3-) at day +21.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗
PubMed1994

The helix-loop-helix protein Id-2 enhances cell proliferation and binds to the retinoblastoma protein.

Cell growth and differentiation are usually antagonistic. Proteins of the basic helix-loop-helix (bHLH) family bind DNA and play important roles in the differentiation of specific cell types. Id proteins heterodimerize with bHLH transcription factors, blocking their activation of lineage-specific gene expression and thereby inhibiting cellular differentiation. To examine the effect of Id-2 on cell proliferation, we overexpressed Id-2 in the human osteosarcoma cell line U2OS. Id-2 expression in U2OS reduced the serum requirement for growth and stimulated cellular proliferation by shortening the doubling time and increasing the percentage of cells in S phase. We demonstrated that Id-2 expression was able to reverse the inhibition of cellular proliferation and the block in cell cycle progression mediated by the product of the retinoblastoma tumor suppressor gene pRB. This effect was not associated with changes in the state of pRb phosphorylation in transfected cells. In vitro, unphosphorylated pRb from cell lysates specifically bound Id-2 but was not able to bind a mutated form of Id-2 lacking the HLH domain that also did not antagonize the growth arrest by pRb. In vitro-synthesized pRb containing mutations within the E1A/large T-binding pocket did not bind Id-2. However, wild-type pRb was able to bind to a region of Id-2 corresponding to only the HLH domain. In vivo, a physical association between Id-2 and pRb was seen in cross-linked extracts from SAOS-2 cells transfected with Id-2 and pRb. Our data identify a role for Id-2 in the regulation of cellular proliferation and suggest that the interaction between Id-2 and pRB is a molecular pathway over which synchronous changes in growth and differentiation are mediated in vivo.

Base Sequence↗
PubMed1994

Clinical pharmacokinetics of carboplatin in children.

The present study was undertaken to evaluate in children the plasma pharmacokinetics of free carboplatin given at different doses and schedules and to evaluate the inter- and intrapatient variability and the possible influence of schedule on drug exposure. A total of 35 children (age range, 1-17 years) with malignant tumors were studied. All patients had normal renal function (creatinine clearance corrected for surface body area, above 70 ml min-1 m-2; range, 71-151 ml min-1 m-2) and none had renal involvement by malignancy. Carboplatin was given at the following doses and schedules: 175, 400, 500, and 600 mg/m2 given as as a 1-h infusion; 1,200 mg/m2 divided into equal doses and infused over 1 h on 2 consecutive days; and 875 and 1,200 mg/m2 given as a 5-day continuous infusion. A total of 57 courses were studied. Carboplatin levels in plasma ultrafiltrate (UF) samples were measured both by high-performance liquid chromatography and by atomic absorption spectrophotometry. Following a 1-h infusion, carboplatin free plasma levels decayed biphasically; the disappearance half-lives, total body clearance, and apparent volume of distribution were similar for different doses. In children with normal renal function as defined by creatinemia and blood urea nitrogen (BUN) and creatinine clearance, we found at each dose studied a limited interpatient variability of the peak plasma concentration (Cmax) and the area under the concentration-time curve (AUC) and a linear correlation between the dose and both Cmax (r = 0.95) and AUC (r = 0.97). The mean value +/- SD for the dose-normalized AUC was 13 +/- 2 min m2 l-1 (n = 57).2+ The administration schedule does not seem to influence drug exposure, since prolonged i.v. infusion or bolus administration of 1,200 mg/m2 achieved a similar AUC (13.78 +/- 2.90 and 15.05 +/- 1.44 mg ml-1 min, respectively). In the nine children studied during subsequent courses a limited interpatient variability was observed and no correlation (r = 0.035) was found between AUC and subsequent courses by a multivariate analysis of dose, AUC, and course number. The pharmacokinetic parameters were similar to those previously reported in adults; however, a weak correlation (r = 0.52, P = 0.03) between carboplatin total body clearance and creatinine clearance varying within the normal range was observed.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1993

Uptake and storage of m-iodobenzylguanidine are frequent neuronal functions of human neuroblastoma cell lines.

The mechanisms of the uptake and release of m-iodobenzylguanidine (MIGB) have been studied in 5 neuroblastoma (NB) cell lines and in 4 clonal NB sublines with a homogeneous phenotype. A specific uptake system for MIBG was found in 8 of 9 NB cell lines or subpopulations. The uptake was characterized by temperature dependency, high affinity, saturability, sodium dependency, and imipramine sensitivity. The majority of NB cell lines that possessed a specific uptake system for MIBG were also able to efficiently store the incorporated drug. However, 3 NB cell lines were identified without the ability to retain high levels of MIBG, despite the presence of a specific uptake system. We also report that a clonal subline, SH-EP1, which has a nonneuroblastic phenotype, failed both MIBG uptake and retention. Conversely, the parental cell line, SK-N-SH, and the neuroblastic subline SH-SY5Y possessed both a specific uptake system and the ability to store MIBG. In addition, the induction of neuronal differentiation with retinoic acid increased the velocity of uptake and the storage efficiency for MIBG in the clonal subline SH-SY5Y. We conclude that MIBG uptake and storage should be considered to be frequent but independent neuronal functions of human NB cells.

3-Iodobenzylguanidine↗
PubMed1993

Critical observations on neuroblastoma treatment with 131-I-metaiodobenzylguanidine at diagnosis.

Results of treatment with 131-I-Metaiodobenzylguanidine (131-I-MIBG) in patients with resistant neuroblastoma appear encouraging if one considers that most of the patients had far advanced, intensively pre-treated disease. To further explore the potential role of this new drug in untreated patients, we treated 3 children with stage III neuroblastoma. All three of our cases received 131-I-MIBG at relatively low dose with the complete disappearance of the tumor mass in case 1, whereas in cases 2 and 3 CT scan showed a significant reduction of the tumor mass and, interestingly enough, no evidence of 131-I-MIBG uptake of a tracer dose in the remaining tumor. Particularly, in case 2, the persistence and subsequent progression of part of the tumor mass without 131-I-MIBG uptake after a therapeutic dose of 131-I-MIBG, which apparently destroyed the 131-I-MIBG-positive cell population, clearly suggest heterogeneity at diagnosis, with a dual neuroblastoma cell population, one with 131-I-MIBG uptake and the other without. Besides the biological implications of the 131-I-MIBG uptake heterogeneity in neuroblastoma at diagnosis, our findings suggest that in stage III neuroblastoma patients even a relatively small dose of 131-I-MIBG administered at diagnosis is sufficient to destroy either the primary tumor completely (case 1) or the part of the tumor (case 2 and 3) which shows 131-I-MIBG uptake, without any significant hematologic toxicity. Furthermore, a single course of 131-I-MIBG at the dosage employed does not appear to jeopardize the subsequent use of chemotherapy. In conclusion, if our data are confirmed by further investigation, 131-I-MIBG may be included as a front line drug shortly followed by chemotherapy in future treatment strategies of advanced neuroblastoma without or with minimal bone marrow infiltration.

3-Iodobenzylguanidine↗
PubMed1992

Germ-line and somatic p53 gene mutations in multifocal osteogenic sarcoma.

Multifocal osteogenic sarcoma patients without familial histories of increased tumor predisposition were examined for mutations in the highly conserved regions of the p53 gene. p53 point mutations were found in tumor DNA from each of the four patients we examined. A germ-line p53 mutation was detected in one of these patients, and a further rearrangement of the residual wild-type allele was detected in tumor tissue. p53 germ-line mutations can contribute to the enhanced predisposition to tumor development manifest in patients with multifocal osteosarcoma.

Base Sequence↗
PubMed1992

[Niemann-Pick disease type C in monozygotic twins].

The Authors describe two monochorionic twins affected by Niemann-Pick disease type C with a clinical picture beginning in the neonatal age and with a progressive mental deterioration, loss of speech and spasticity started at 30 months. The importance of cultured skin fibroblasts is emphasized. The evidence of a defective intracellular cholesterol esterification is established as an intrinsic feature of Niemann-Pick disease type C.

Cells, Cultured↗
PubMed1992

Reference values for immunoglobulin kappa and lambda light chains and the kappa/lambda ratio in children's serum.

We analyzed 708 serum samples from healthy children and adolescents by immunonephelometry to obtain reference values for the immunoglobulin kappa (kappa) and lambda (lambda) light chains and for their ratio at a time of life when immunoglobulin synthesis is maturing and continually being stimulated. The lambda chain concentration that is to be maintained throughout the child's life is reached very early, just after 1 year, whereas the concentration of the kappa chains, which increases gradually, reflects the concentration of the immunoglobulins as a whole. These reference values may be useful for studying kappa and lambda chains in illnesses involving the immune system in children.

Adolescent↗