Search PubMed⌕ Search

Biomedical subjects

G Giaccone

Publications and source records attributed to G Giaccone.

At least 181 records · Page 10Linked to original sources
PubMed1996

beta PP and Tau interaction. A possible link between amyloid and neurofibrillary tangles in Alzheimer's disease.

Extracellular deposition of amyloid fibrils and intraneuronal accumulation of paired helical filaments (PHFs) are the neuropathological hallmarks of Alzheimer's disease. The major constituent of amyloid fibrils is a 39- to 43-residue peptide (termed A beta), which is derived from a 695- to 770-amino-acid precursor protein (termed beta PP). The main component of PHFs identified so far is the microtubule-associated protein tau. Yet, there is no direct evidence of interconnection between these two pathological states. We report here that antibodies to an epitope located between residues 713 and 723 of beta PP770 (ie, the transmembrane region of beta PP distal to A beta) consistently labeled PHFs in the brain of Alzheimer patients. Solid phase immunoassay showed that a peptide homologous to residues 713 to 730 of beta PP770 bound tau proteins. This beta PP peptide spontaneously formed fibrils in vitro and, in the presence of tau, generated dense fibrillary assemblies containing both molecules. These data suggest that beta PP or beta PP fragments containing the tau binding site are involved in the pathogenesis of PHFs in Alzheimer's disease.

Alzheimer Disease↗
PubMed1996

Broad distribution of the multidrug resistance-related vault lung resistance protein in normal human tissues and tumors.

Multidrug resistance (MDR) to anticancer drugs is a major cause of treatment failure in cancer. The lung resistance protein LRP is a newly described protein related to MDR in several in vitro models. LRP has been shown to be a strong predictor of poor response to chemotherapy and prognosis in acute myeloid leukemia and in ovarian carcinoma patients. Recently, based on a 57% and 88% amino acid identity with major vault proteins from Dictyostelium discoideum and Rattus norvegicus, respectively, we identified LRP as the human major vault protein, the main component of highly conserved cellular organelles named vaults. We have studied the immunohistochemical expression of LRP in freshly frozen normal human tissues and 174 cancer specimens of 28 tumor types. LRP was broadly distributed in normal and malignant cells, but distinct patterns of expression were noticed. High LRP expression was seen in bronchus, digestive tract, renal proximal tubules, keratinocytes, macrophages, and adrenal cortex whereas varying ing levels were observed in other organs. LRP was detected in all tumor types examined, but its frequency varied, fairly reflecting the chemosensitivity of different cancers. For example, low rates of LRP positivity were seen in testicular cancer, neuroblastoma, and acute myeloid leukemia; intermediate in ovarian cancer; and high in colon, renal, and pancreatic carcinomas. The wide occurrence of LRP in normal and transformed cells in humans, its similar distribution to that of vaults in other species, as well as the high level of conservation among eukaryotic cells of both the amino acid sequence of the major vault protein and the composition and structure of vaults, suggest that vault function is important to eukaryotic cells.

Adult↗
PubMed1996

Results of the phase II EORTC study comparing paclitaxel/cisplatin with teniposide/cisplatin in patients with non-small cell lung cancer. EORTC Lung Cancer Cooperative Group.

Toxicity and response rates are evaluated in a randomized phase II study comparing paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ)/cisplatin with teniposide/cisplatin in the treatment of non-small cell lung cancer to decide whether this study should continue as a phase III trial. A response was seen in 26% (10 of 38) of the patients receiving teniposide/cisplatin and in 40% (14 of 35) of those receiving paclitaxel/cisplatin. Overall, evidence of toxicity was more severe in the cisplatin/teniposide group, especially with regard to myelotoxicity. Grade 4 neutropenia was seen in 66% of patients receiving teniposide compared with 29% of those treated with paclitaxel/cisplatin. The study is to continue as a phase III trial, with 150 patients expected to participate in each treatment group.

Adult↗
PubMed1995

Differential expression of DNA topoisomerases in non-small cell lung cancer and normal lung.

UNLABELLED: DNA topoisomerases are ubiquitous nuclear enzymes, and important targets of cancer chemotherapy. Expression of topoisomerase genes is often correlated with in vitro chemosensitivity. We investigated the expression of the topoisomerase genes in normal lung and non-small cell lung cancer. Expression of topoisomerase II-alpha, topoisomerase II-beta, and topoisomerase I genes has been assessed in tumor samples of 60 patients who underwent operation for a non-small cell lung carcinoma, by RNase protection assay, and by immunohistochemistry. The expression of topoisomerase II-alpha gene was either undetectable or very low in normal lung, while most NSCLC expressed readily quantifiable levels of this gene. No alteration of the topoisomerase II-alpha gene was found by Southern blotting in the NSCLC samples. In contrast to topoisomerase II-alpha, topoisomerase II-beta was expressed in most normal as well as in tumor tissue samples, at a similar level. The levels of expression of both topoisomerase II isoforms was lower than that of human lung cancer cell lines. The results of the topoisomerase II mRNA expression were confirmed by immunohistochemistry. Whereas topoisomerase II-alpha staining was mainly limited to the nucleus, staining with topoisomerase II-beta antibody was exclusively observed in nucleoli. Topoisomerase I was localized in the nuclei and expression was mainly limited to tumor cells. By RNase protection, topoisomerase I expression in NSCLC samples was in the range of that of human lung cancer cell lines. The expression of the topoisomerase genes did not seem to be coordinated. In tumor cells, there was a positive association between expression of topoisomerase II-alpha and Ki-67, a marker of cell proliferation, as assessed by immunohistochemistry, but not with topoisomerase II-beta or topoisomerase I. Clinical characteristics of the patients, and their survival did not appear to be correlated to the level of expression of any of the topoisomerase genes, although a trend towards a shorter survival was observed in patients whose tumors expressed relatively high topoisomerase II-alpha mRNA levels. IN CONCLUSION: (1) the two isoforms of topoisomerase II are differentially expressed in normal lung and NSCLC cells; (2) higher topoisomerase II-alpha expression is associated with higher cell proliferation in NSCLC; (3) the expression of topoisomerase II-alpha and topoisomerase I, but not of topoisomerase II-beta, was higher in tumor cells compared to normal lung. Given the differential expression of topoisomerases in normal lung and tumors, research of more potent and specific topoisomerase inhibitors might prove beneficial in non-small cell lung cancer. Immunohistochemistry may be indicated in prospectively investigating the correlation between expression of topoisomerases and results of chemotherapy treatment.

Aged↗
PubMed1995

Drug resistance-associated marker Lrp for prediction of response to chemotherapy and prognoses in advanced ovarian carcinoma.

BACKGROUND: Drug resistance is a major impediment to the successful treatment of ovarian carcinoma. None of the earlier-identified resistance mechanisms, such as overexpression of the MDR1 gene product, P-glycoprotein (Pgp), has been shown to be a major determinant of clinical response to chemotherapy and survival for ovarian cancer patients. The multidrug resistance-associated protein (Mrp) and the lung resistance protein (Lrp, also called the p110 major vault protein), are newly described proteins associated with multidrug resistance in vitro. PURPOSE: The aim of this retrospective study was to investigate the expression of Mrp and Lrp, in addition to Pgp, in advanced ovarian carcinoma and to determine whether such expression was predictive of response to chemotherapy and survival. METHODS: Fifty-seven banked frozen specimens, previously collected and frozen at the time of diagnosis from an equal number of patients with International Federation of Gynecology and Obstetrics (FIGO) stage III or IV ovarian carcinoma, were immunostained for Pgp (with monoclonal antibodies [MAbs] MRK-16 and JSB-1), Mrp (with MAb MRPrl), and Lrp (with MAb LRP-56). All patients had received platinum- or alkylating-based chemotherapy after debulking surgery. Clinicopathologic parameters determined at diagnosis were retrospectively assessed for their relationship with Pgp, Mrp, and Lrp expression. Response to treatment and survival were compared between Pgp, Mrp, and Lrp expression groups. Qualitative variables were analyzed using Fisher's exact test or the chi-squared test. All reported P values are two-tailed. RESULTS: Nine (16%), 39 (68%), and 44 (77%) of the 57 tumor specimens examined showed positive immunostaining for Pgp, Mrp, and Lrp, respectively. Positive immunostaining for these proteins was not associated with any other prognostic factor examined. No association was found between Pgp and Mrp expression and response to chemotherapy and survival. In contrast, patients with Lrp-positive tumors had poorer response to chemotherapy (P = .004) and shorter progression-free (P = .003) and overall (P = .007) survival than Lrp-negative patients. Multivariate analysis of Lrp expression, FIGO stage, residual tumor after initial surgery, tumor grade, and presence or absence of ascites showed that only Lrp status was independently related to both progression-free survival and overall survival. CONCLUSIONS: Positive Lrp immunostaining in advanced ovarian carcinoma appears to be an indicator of poor response to standard chemotherapy (platinum or alkylating agents) and of adverse prognoses. IMPLICATIONS: The functional characterization of Lrp and related proteins may reveal new approaches to modulate Lrp-associated drug resistance. A large prospective study is warranted to confirm the prognostic value of Lrp.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

MRP gene overexpression in a human doxorubicin-resistant SCLC cell line: alterations in cellular pharmacokinetics and in pattern of cross-resistance.

The development of non-P-glycoprotein-mediated multi-drug resistance is a frequent event among lung-cancer cell lines. In an attempt to understand the underlying mechanisms of this phenotype, we have selected a multi-drug-resistant subline (POGB/DX) in vitro for doxorubicin resistance. The original cell line (POGB) was established in vitro from a non-treated patient with a small-cell lung cancer. POGB/DX cells were cross-resistant to other drugs, associated with MDR phenotype. In contrast, they were not resistant to taxol, camptothecin or melphalan, but were instead hypersensitive to 5-fluorouracil. Although expression of the mdr-1 gene was not detected in POGB/DX cells, cellular pharmacokinetics showed a reduced drug accumulation and altered intracellular localization in the POGB/DX cell line. This defect in drug accumulation was associated with overexpression and amplification of the MRP gene. Interestingly, verapamil, a known modulator of P-glycoprotein function, was able to reverse drug resistance and to increase drug accumulation. In Northern-blot analysis no differences in expression of topoisomerase I and II (alpha and beta), DNA polymerase beta, or HSP70 and HSP60 genes were observed between POGB and POGB/DX. Coupled to lack of changes in expression of known resistance factors, overexpression of MRP and modulation by verapamil strongly support a role for this gene product in the development of drug resistance in this SCLC cell system. This study provides evidence that (a) altered cellular pharmacokinetics is related to MRP expression; (b) MRP-mediated phenotype is characterized by a specific pattern of cross-resistance, which does not involve taxol; and (c) verapamil may be effective in modulating the function of the MRP gene product.

Carcinoma, Small Cell↗
PubMed1995

Differential expression of the c-kit proto-oncogene in germ cell tumours.

The c-kit proto-oncogene product and its ligand stem cell factor play an important role in haematopoiesis, spermatogenesis, and melanogenesis. Using an anti-c-kit antiserum raised against a synthetic peptide, we studied the immunohistochemical expression of the c-kit gene product in 60 germ cell tumours (GCTs) (53 testicular, 7 extragonadal), derived from primary GCTs in 45 cases and metastatic tumours in 15 cases. Twenty-eight out of 28 seminomas showed c-kit membranous staining in the majority of cells. A similar pattern of expression was seen in intratubular germ cell neoplasia. Nine out of 29 (32 per cent) non-seminomas displayed cytoplasmic, but not membranous, c-kit immunoreactivity in occasional cells. In three mixed GCTs, c-kit expression was limited to the seminoma component. In normal testis, c-kit expression was observed in some basal tubular cells, corresponding to undifferentiated spermatogonia. These results suggest a role for c-kit in the oncogenesis of GCT, where down-regulation of c-kit might be a critical step during progression from seminomas to non-seminomas. Immunohistochemical analysis of c-kit should be considered as a diagnostic aid for GCT and in particular may be helpful in the identification of certain extragonadal seminomas.

Adolescent↗
PubMed1995

New drugs in non-small cell lung cancer. An overview.

Chemotherapy is rather ineffective in non-small cell lung cancer. However, in the last few years, a number of new anticancer agents have been developed which have definite activity in this disease. Among them are the taxanes and CPT-11, drugs with novel mechanisms of action, new antimetabolites (edatrexate and gemcitabine), and a new vinca alkaloid (vinorelbine). Furthermore, in the near future, the better understanding of lung cancer biology will help in devising new treatment strategies.

Antimetabolites, Antineoplastic↗
PubMed1995

Effects of suramin on human lung cancer cell lines.

Suramin cytotoxicity was studied in a panel of human lung cancer cell lines by the MTT assay. The concentrations of suramin which induced 50% growth inhibition (IC50) ranged from 130 to 3715 microM for the cell lines growing in medium containing 10% fetal calf serum (FCS). In only one cell line was the IC50 at a concentration that can be reached in plasma of patients treated with suramin. Suramin was 18 and 3.3 times more cytotoxic on NCI-N417 cells growing in 2% FCS and in HITES serum-free medium, respectively, than growing in 10% FCS. No difference in suramin cytotoxicity was observed between small and non-small cell lung cancer cell lines. At the lower concentrations tested, suramin stimulated proliferation of the two small cell lung cancer cell lines, NCI-H187 and NCI-N417. Of several growth factors tested, none induced stimulation of growth in NCI-H187 and NCI-N417 cell lines, nor did they in any way alter the stimulatory effect of suramin. Cell counting, DNA flow cytometric analysis and Ki-67 staining confirmed a higher proliferative state in suramin-exposed NCI-H187 cells as compared with untreated cells. However, topoisomerase II-alpha gene expression remained unchanged, as assessed by northern blot analysis and immunostaining. Suramin had an inhibitory effect on topoisomerase II activity, as assessed by the kDNA decatenation assay, with an IC50 of approximately 40 microM. In conclusion, suramin has significant cytotoxic activity in a minority of human lung cancer cell lines, and it stimulates proliferation in some instances. The pleiotropic action of suramin observed should caution on the possibility of tumour acceleration in patients being treated with this drug.

Blotting, Northern↗
PubMed1995

DT-diaphorase activity in normal and neoplastic human tissues; an indicator for sensitivity to bioreductive agents?

DT-diaphorase (DTD) is an important enzyme for the bioreductive activation of the new alkylating indoloquinone EO9. In preclinical studies, EO9 has shown selective anti-tumour activity against solid tumours and under hypoxic conditions. The levels of three reductive enzymes have been determined in three types of human solid tumours, together with corresponding normal tissues and normal liver. DTD enzyme activities were measured in tumour extracts using 2,6-dichlorophenolindophenol (DCPIP) and NADH as substrates; cytochrome P450 reductase or cytochrome b5 reductase activities were assessed with cytochrome c and NADPH or NADH respectively. DTD activity was highest in non-small-cell lung (NSCLC)-tumours (mean 123 nmol DCPIP min-1 mg-1), followed by colon carcinoma (mean 75 nmol min-1 mg-1) and squamous cell carcinoma of the head and neck (6-fold lower than NSCLC). DTD activity was very low in normal liver and normal lung (4-6 nmol min-1 mg-1), while the levels in normal colon mucosa or normal mucosa of the head and neck region were in the same range as the corresponding tumours. The levels of the two other reductive enzymes, cytochrome P450 reductase (CP450R) and cytochrome b5 reductase (Cb5R), were 5 to 25-fold lower than those of DTD in all the tissues, except for normal liver, in which DTD was 2 to 4-fold lower. The degree of variation found for DTD (range 4-250 nmol min-1 mg-1), was not observed for these enzymes (CP450R, 0.8-7.8 nmol cytochrome c min-1 mg-1; Cb5R, 3.5-27.6 nmol min-1 mg-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Antineoplastic Agents↗
PubMed1995

Tau protein directly interacts with the amyloid beta-protein precursor: implications for Alzheimer's disease.

The simultaneous presence of intracellular neurofibrillary tangles (NFT) and extracellular senile plaques in Alzheimer's disease (AD) suggests that the two lesions could be synergistically interrelated. However, although the main protein components of NFT and senile plaques, tau (tau) and amyloid beta-protein, respectively, are well characterized, the molecular mechanisms responsible for their deposition in lesions are unknown. We demonstrate, using four independent techniques, that tau directly interacts with a conformation-dependent domain of the amyloid beta-protein precursor (beta PP) encompassing residues beta PP714-723. The putative tau-binding domain includes beta PP717 mutation sites that are associated with familial forms of AD. Our findings strongly suggest that NFT and senile plaques, often thought of as independent structures, may play a role in each other's formation during the pathogenesis of AD.

Alzheimer Disease↗
PubMed1995

Prognostic relevance of P-glycoprotein expression in breast cancer.

BACKGROUND: P-glycoprotein (Pgp) expression has been reported to be associated with a poor prognosis in some malignancies such as neuroblastoma, soft tissue sarcoma and acute myeloid leukemia. The prognostic role of Pgp expression in breast cancer is still unclear. We investigated the expression of Pgp in primary and metastatic breast cancer tissues in relation to patient characteristics and treatment outcome. PATIENTS AND METHODS: Pgp expression was evaluated in 92 primary and 12 metastatic breast cancers by the use of immunohisto/cytochemistry with three monoclonal antibodies (MAbs) (JSB-1, C219, MRK16), and an RNAse protection assay. Follow-up information was available for 77 primary breast cancer patients (median follow-up 42 months; range 2-63 months). RESULTS: Concordance among the anti-Pgp MAbs varied, the highest being between JSB-1 and MRK16 (71%; p=0.002). Pgp expression was more frequent in metastatic disease (58%) than in primary breast cancer (29%) (JSB-1; p=0.055). Pgp expression as assessed with JSB-1 (univariate analysis; p<0.05) was associated with shorter overall survival (OS). Nineteen (21%) primary breast cancers had Pgp expression in fibroblasts in desmoplastic stroma and this did not correlate with Pgp expression in the tumor. The combination of Pgp-positive tumor cells and Pgp-expressing fibroblasts was the strongest prognostic factor for OS by multivariate analysis. Subgroup analysis suggested that Pgp expression was associated with a shorter OS in tamoxifen-treated patients, but not in those who received chemotherapy (most often CMF). CONCLUSIONS: Pgp expression in tumor cells, and especially when accompanied by Pgp expression in fibroblasts in desmoplastic stroma, has prognostic value in primary breast cancer patients and is likely to be a marker of a more malignant phenotype. Pgp expression of tumor cells might play a role in tamoxifen resistance. These findings may have important implications for teh treatment of breast cancer patients, and warrant further prospective investigation in a larger patient population.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Multidrug resistance proteins and other drug transport-related resistance to natural product agents.

The term multidrug resistance is defined in this article as cellular resistance to anticancer agents due to a decreased concentration of active drug at the target sites that is caused by increased metabolism or altered transport or routing of the active drug species. Resistance related to alterations in the drug targets or apoptotic pathways is not discussed. Until recently multidrug resistance was associated almost exclusively with p-glycoprotein (Pgp)-overexpression. However, other non-Pgp-related mechanisms have been tracked down. It has been shown that transfection of the gene that encodes a novel drug transport protein, the multidrug resistance protein, induces cross-resistance for many multidrug resistance drugs as well as active transport of daunorubicin from tumor cells. Surprisingly, it has also been found that multidrug resistance protein mediates transport of negatively charged species that are not classic multidrug resistance drugs, such as leukotriene C4 and other glutathione conjugates as well as negatively charged dyes. It was therefore suggested that multidrug resistance protein is identical with the multispecific organic anion transporter. The transport rate of several positively charged drugs (vincristine, rhodamine-123, daunorubicin) by multidrug resistance protein appeared to be dependent on the cellular glutathione levels. Multidrug resistance protein seems to be constitutively expressed in normal tissues at a low level with few tissues having higher expression. Multidrug resistance protein overexpression in in vitro-selected MDR cell lines occurs relatively frequently in lung cancer and leukemia cell lines and often precedes Pgp overexpression. Differential expression has been demonstrated in tumor samples, which suggests a role in resistance to chemotherapy in at least certain tumor types. Modulation studies of multidrug resistance protein activity are still scarce. Other non-Pgp, non-multidrug resistance protein multidrug resistance mechanisms probably exist but have not been identified at the molecular level as yet.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Gerstmann-Sträussler-Scheinker disease (PRNP P102L): amyloid deposits are best recognized by antibodies directed to epitopes in PrP region 90-165.

Gerstmann-Sträussler-Scheinker (GSS) disease is a familial neurological disorder pathologically characterized by accumulation of prion protein (PrP) in the form of fibrillary and non-fibrillary deposits within the cerebrum and cerebellum. We have studied two patients in whom the disease is caused by a leucine for proline amino acid substitution at residue 102 of PrP. In both patients, the neuropathologic findings are similar, consisting of spongiform changes, amyloid deposits, and gliosis. To investigate the antigenic profile of PrP deposits, we used antibodies raised against several peptides that correspond to segments of the N-terminus, repeat region, midregion, and C-terminus of PrP. By immunohistochemistry, PrP amyloid cores are best labeled by antibodies directed to epitopes spanning PrP residues 90-165. In GSS disease caused by a substitution of thymine to cytosine at PRNP codon 198 (Indiana kindred), the major amyloidogenic peptide spans residues 58-150; therefore, in these two genetic forms of GSS disease, amyloid may be composed of different peptides.

Adult↗
PubMed1995

Gerstmann-Sträussler-Scheinker disease and the Indiana kindred.

Gerstmann-Sträussler-Scheinker disease is an autosomal dominant disorder with a wide spectrum of clinical presentations including ataxia, spastic paraparesis, extrapyramidal signs, and dementia. The patients present with symptoms in the third to sixth decade of life and the mean duration of illness is five years. Mutations at codons 102, 105, 117, 145, 198 and 217 of the open reading frame of the prion protein gene have been associated with GSS disease. As a result of the mutations, a substitution at the corresponding residues of the prion protein occurs, or as in the case of the STOP mutation at codon 145, a truncated protein is produced. Neuropathologically, the common denominator is a cerebral prion protein amyloidosis; however, there is significant variability in the pattern of amyloid deposition in regions of the central nervous system among reported families. Amyloidosis coexists with severe spongiform degeneration in patients with the mutation at codon 102, and with neurofibrillary degeneration in the patients with mutation at codons 145, 198 and 217. The development of a transmissible spongiform encephalopathy in animals inoculated with brain tissue from affected subjects with mutation at codon 102 suggests that in some forms of genetically-determined Gerstmann-Sträussler-Scheinker disease, and particularly those characterized by severe spongiosis, amyloidogenesis and production of an infectious "agent" occur concomitantly via mechanisms that are only partially understood.

Amyloid↗