Search PubMed⌕ Search

Biomedical subjects

G Favre

Publications and source records attributed to G Favre.

At least 55 records · Page 3Linked to original sources
PubMed1997

GGTI-298 induces G0-G1 block and apoptosis whereas FTI-277 causes G2-M enrichment in A549 cells.

The mechanism by which the geranylgeranyltransferase I inhibitor GGTI-298 and the farnesyltransferase inhibitor FTI-277 inhibit human tumor growth is not known. Herein, we demonstrate that in the human lung adenocarcinoma A549 cells, GGTI-298 induced a G1-G0 block whereas FTI-277 induced an enrichment in the G2-M phase of the cell cycle. Although FTI-277, GGTI-298, and compactin inhibited A549 cell growth, only GGTI-298 and compactin induced apoptosis as demonstrated by four criteria: 4',6-diamidine-2-phenylindoledihydrochloride staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, DNA fragmentation assay, and flow cytometry. Furthermore, the involvement of geranylgeranylated proteins in apoptotic pathways was confirmed by demonstrating that geranylgeraniol was able to block the ability of compactin to induce apoptosis. These results suggest that protein geranylgeranylation is critical for the control of programmed cell death and that, in A549 cells, farnesylated and geranylgeranylated proteins are involved in G2-M and G0-G1, respectively.

Adenocarcinoma↗
PubMed1997

Radioresistance induced by the high molecular forms of the basic fibroblast growth factor is associated with an increased G2 delay and a hyperphosphorylation of p34CDC2 in HeLa cells.

The basic fibroblast growth factor-(bFGF) mediated signal transduction pathway has been implicated in cellular resistance to ionizing radiation. bFGF is synthesized from the same mRNA in four isoforms resulting from alternative initiations of translation at three CUG start codons (24, 21.5, and 21 kDa) and one AUG start codon (18 kDa). We analyzed the implication of high- and low-molecular forms of bFGF in radioresistance acquisition. For this, we transfected HeLa cells with retroviral vector containing either the CUG-initiated 24-kDa molecular form (HeLa 3A cells), the AUG-initiated 18-kDa molecular bFGF form (HeLa 5A cells), or the vector alone (HeLa PINA cells). A significantly increased radioresistance was obtained only in HeLa 3A cells (Dq = 810 +/- 24 cGy) compared with wild-type cells (Dq = 253 +/- 49 cGy) or HeLa PINA cells (Dq = 256 +/- 29 cGy; P < 0.001). This radioprotective effect was independent of an inhibition of radiation-induced apoptosis but related to an increased G2 duration after irradiation and to an hyperphosphorylation of p34cdc2 kinase. Knowledge of the high-molecular bFGF form-induced radioresistance pathway could offer novel targets for decreasing the radioresistance phenotype of tumors expressing high amounts of bFGF, such as glioblastoma.

Apoptosis↗
PubMed1997

Improved oligonucleotide uptake and stability by a new drug carrier, the SupraMolecular Bio Vector (SMBV).

Antisense oligodeoxynucleotides are potential therapeutic agents, but their development is still limited by both a poor cellular uptake and a high degradation rate in biological media. The strategy that we propose to face these problems is to use small synthetic carriers, around 30 nm diameter, the SupraMolecular Bio Vectors (SMBV). We used positively charged SMBV and settled the ionic incorporation of negatively charged oligonucleotides into these carriers. A minimal leakage of 10% of total incorporated oligonucleotides was then measured during two months. Both protection and uptake of oligonucleotides were then analyzed. On the one hand, we showed that the incorporation of oligonucleotides into the selected SMBV allows to significantly increase, 8 times, their half-life, in cell growth medium. On the other hand, the internalization of the SMBV, into cells, by an endosomal pathway has been characterized. The essential point is that the SMBV uptake elicits the simultaneous oligonucleotide uptake. The oligonucleotide amount that goes through cells within 5 h can be up to 30 times higher than for free oligonucleotides and the fraction of oligonucleotides that is present in the cytosol is increased up to 10 fold after incorporation into the SMBV. This study demonstrates the ability of SMBV to improve oligonucleotide cellular behaviour.

Animals↗
PubMed1997

Preferential cytoplasmic localization of p34cdc2 in recurrent human squamous cell carcinoma after radiotherapy.

Duration of the G2-phase delay and arrest after exposure to ionizing radiation is thought to influence radiosensitivity. The kinase activity of the p34cdc2-cyclin B complex and the p34cdc2-cyclin A complex is implicated in G2- to M-phase transition and in G2-phase arrest after exposure to ionizing radiation. We analyzed the expression level and the subcellular location of p34cdc2, cyclin A and cyclin B in head and neck squamous cell carcinoma (SCC) tumors; samples were obtained from patients with locally nonrecurrent and recurrent tumors that had been treated by surgery and radiotherapy. No significant difference was noticed in cyclin A, cyclin B and p34cdc2 expression. However, we noted a significant preferential cytoplasmic location of p34cdc2 in recurring tumors compared to the nonrecurring ones (P < 0.001). This abnormal location of p34cdc2 occurs even in primary tumors in patients with recurring tumors, suggesting that a default in the activation of p34cdc2 kinase could be implicated in clinical radioresistance.

CDC2 Protein Kinase↗
PubMed1996

Farnesol and geranylgeraniol induce actin cytoskeleton disorganization and apoptosis in A549 lung adenocarcinoma cells.

The effects of exogenous isoprenoids were investigated on A549 human lung adenocarcinoma cells. Among the tested isoprenoids, only farnesol and geranylgeraniol induce actin cytoskeleton disorganization, growth inhibition, and apoptosis. In contrast, desmosterol leads only to growth inhibition. We show that all tested isoprenoids are potent inhibitors of HMG CoA reductase activity, the sterols being the most powerful while they induce neither F-actin disorganization nor apoptosis. Thus the molecular mechanisms induced by farnesol and geranylgeraniol appear independent of reductase regulation. Our results point out the specific role of farnesol and geranylgeraniol on actin cytoskeleton organization and apoptosis in adenocarcinoma cells.

Actins↗
PubMed1996

A new family of potential oncostatics: 2-chloroethylnitrososulfamides (CENS)--I. Synthesis, structure, and pharmacological evaluation (preliminary results).

A new series of alkylating agents, 2-chloroethylnitrososulfamides (CENS), were developed on the model of 2-chloroethylnitrosoureas. Starting from chlorosulfonyl isocyanate, a four-step synthesis (carbamoylation-sulfamoylation, Mitsunobu alkylation, deprotection, and nitrosation) gives the title compounds in a 47-58% overall yield. The selection of the nitrosation site can be directed through an alternative route. The pharmacological evaluation shows a significant oncostatic activity towards both A549 and MCF7 cell lines.

Antineoplastic Agents, Alkylating↗
PubMed1996

Involvement of tyrosine kinase activity in the low-density lipoprotein receptor expression in human lung adenocarcinoma cell line A549.

In common with other tumour cell lines but in contrast to normal cells, the human adenocarcinoma cell line A549 showed a biphasic regulation of the LDL receptor activity during growth both LDL binding and metabolism (sum of internalised and degraded LDL) increased during the log exponential growth phase and decreased when the cells approached confluence. This period of increasing LDL receptor activity coincided with a high resistance to cholesterol down-regulation which suggested a sterol-independent pathway of stimulation. Since A549 cells have an autocrine loop of growth factors, two of which have tyrosine kinase activity, the LDL receptor activity was tested in the presence of the tyrosine kinase inhibitor, genistein. When cells were incubated in the absence of cholesterol (LPDS medium), the inhibition that occurred was two-fold higher during the exponential growth phase than during the confluent phase. Moreover, the residual LDL binding and metabolism after genistein inhibition were completely resistant to down-regulation by cholesterol only during the growth phase. When cholesterol was present (FCS medium). inhibition was observed only during the growth phase. The inhibition of LDL receptor activity by genistein was found to be the result of a loss in the number of LDL binding sites, while the dissociation constant was not affected. This loss was accompanied by a disappearance of mRNA as shown by RNase mapping. By comparison, LDL receptor activity of normal cells (fibroblasts) was also affected by genistein during the exponential growth phase but was much more cholesterol-dependent. Taken together, these results suggest that the tyrosine kinase pathway is essential to up-regulate LDL receptor expression in highly dividing cells and particularly in tumour cells in which the sterol regulation is deficient.

Adenocarcinoma↗
PubMed1996

Potential prognostic value in human breast cancer of cytosolic Nme1 protein detection using an original hen specific antibody.

The metastasis-suppressor nme gene (also called nm23), first identified in murine melanoma cells, exists as two forms in human: nme1 and nme2. However, only the lack of expression of nme1 has been related to distant metastasis appearance in human breast cancer. The aim of this work was first to raise specific antibodies to allow the analysis of Nme1 and then, with this specific tool, to evaluate the predictive value of Nme1 detection in cytosolic extracts of human breast tumours. We obtained a hen antibody that specifically reacts with Nme1 without any cross-reaction with Nme2. We analysed the expression of the protein in 59 human breast tumours and found a significant relationship between this expression and oestrogen receptor status (P<0.001). Moreover, Nme1 expression is related to metastasis-free survival (P<0.001) and survival of patients (P<0.001). The determination of Nme1 expression in primary tumours using our antibody should be an interesting predictive test of the metastasis for clinical investigations.

Animals↗
PubMed1995

Involvement of the Ca(2+)-dependent phosphorylation of a 20 kDa protein in the proliferative effect of high-density lipoproteins (subclass 3) on the adenocarcinoma cell line A549.

Previous studies from our laboratory demonstrated that high-density lipoproteins (subclass 3; HDL3) bind to sites specific for apolipoprotein AI on the human adenocarcinoma cell line A549 and that HDL3 binding promotes a mitogenic effect [Favre, Tazi, Le Gaillard, Bennis, Hachem and Soula (1993) J. Lipid Res. 34, 1093-1106]. In the present study, we have examined the cell proteins that showed modified phosphorylation after binding of HDL3 to specific sites, and the roles of Ca2+ and protein kinase C. Native HDL3 (but not tetranitromethane-modified HDL3) and Ca2+ ionophore A23187 strongly enhanced the phosphorylation of a 20 kDa protein (x 3.6) and, to a lower extent, the phosphorylation of 24 and 28 kDa proteins (x 2.2 and 2.6 respectively). The two effectors were equally able to stimulate cell growth. Down-regulation of protein kinase C by a 24 h incubation of cells with phorbol myristate acetate prevented the effects of HDL3 on the phosphorylation of 24 and 28 kDa proteins. However, the extent of phosphorylation of the 20 kDa protein was not affected. In contrast, activation of protein kinase C by a short incubation with phorbol myristate acetate resulted in inhibition of proliferation and an increase in 24 and 28 kDa (but not 20 kDa) protein phosphorylation. These results suggest that HDL3 putative receptors exert their proliferative effect on A549 cells through activation of a Ca(2+)-dependent protein kinase. This kinase activity is not modulated by phorbol ester and thus may be a calmodulin kinase or an isoenzyme of protein kinase C that is independent of phorbol ester. It allows a subsequent 20 kDa protein to be phosphorylated.

Adenocarcinoma↗
PubMed1995

Reversion of transformed phenotype of human adenocarcinoma A549 cells by expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase complementary DNA.

3-Hydroxy-3-methylglutaryl CoA reductase (HMG-CoA reductase) plays a rate-limiting role in isoprenoid biosynthesis and is associated with cell proliferation and transformation. Although an elevated level of HMG-CoA reductase activity is consistently detected in cancer cell lines and tumors, the question remains whether HMG-CoA reductase activity may have a causative role in cell transformation. We have stably transfected the A549 human adenocarcinoma cells with both bicistronic and retroviral expression vectors, including the whole cDNA of human HMG-CoA reductase. Stably transfected cells showed strong morphological changes and disorganization in the filamentous actin architecture, became contact inhibited, and had a lower doubling time. Moreover, they exhibited anchorage-independent growth reduction and lost their capability to induce tumors in nude mice. Surprisingly, no quantitative modification of enzyme activity was observed following transfection, although expression of HMG-CoA reductase cDNA was shown by Northern blot analysis. When endogenous and transfected reductase activity was bypassed by the addition of mevalonate and compactin, a competitive inhibitor, the filamentous actin distribution in HMG-CoA reductase-transfected cells became very similar to that of control cells, demonstrating the role of exogenous HMG-CoA reductase activity in this process. All of our data together strongly suggest that phenotype reversion is dependent on exogenous HMG-CoA reductase expression and that enzymatic activity is implied in this mechanism. HMG-CoA reductase cDNA expression, by expression of a particular form of reductase, might be a negative regulator of cell growth and thus reverse the phenotype of tumor cells.

Acyl Coenzyme A↗
PubMed1993

Importance of mevalonate-derived products in the control of HMG-CoA reductase activity and growth of human lung adenocarcinoma cell line A549.

HMG-CoA reductase catalyzes the synthesis of mevalonate, a crucial intermediate in the biosynthesis of cholesterol and non-sterol isoprenoid compounds essential for cell growth. The HMG-CoA reductase activity of the A549 tumor cell line is higher than that of normal human fibroblasts. This deregulation in mevalonate needs was not due to an alteration in the activated state of the enzyme by short-term regulation. We show that the HMG-CoA reductase in A549 cell line was subject to a multivalent feedback control. A high fraction (40%) of the reductase activity was devoted to non-sterol products. In contrast, normal fibroblasts had only 15-20% of the reductase activity that generated non-sterol products. We also show that cholesterol and at least one of the non-sterol products are necessary for optimal cell growth of A549 cells. Our data strongly suggest that A549 cells produce more non-sterol substances which may be related to increased requirements of mevalonate for upregulated cell growth.

Adenocarcinoma↗
PubMed1993

Biodistribution study of 99mTc-labeled LDL in B16-melanoma-bearing mice. Visualization of a preferential uptake by the tumor.

Since there is strong evidence of a preferential LDL accumulation in tumor cells, LDL might be of interest for tumor imaging. We have tested the ability of 99mTc-LDL in tumor imaging with B16-melanoma-bearing mice as a model for further applications in human studies. The LDL fixation rate was higher with 99mTc-labeled LDL than with 125I labeled LDL. Since technetium-99m remains trapped in the cells, 99mTc-LDL is a well-adapted radioligand because of information given by this radiotracer on the receptor metabolism. We observed that, at early growth stages, the tumor took up the LDL at a maximal rate, suggesting differences in cholesterol metabolism as a function of tumor growth. Accumulation of label in the tumor area was perfectly observable in tumor-bearing mice on scintigraphic images. Computerized quantification of the regions of interest (as well as biodistribution studies including killing of the animals) showed a 1.81-fold increase in uptake by the tumor as compared to the liver and a 28-fold increase as compared with corresponding normal tissue (muscle of the left leg) at day 8 of tumor growth. These data give strong support to the value of this non-invasive method in visualizing and quantifying the tissue LDL uptake in vivo, including the precise information provided by nuclear scintigraphy on the distribution of the radiolabeled LDL in the different tissues. 99mTc-LDL could be an efficient tool for further diagnostic or therapeutic exploration in cancer patients.

Animals↗
PubMed1993

Factors associated with transfusion requirements during treatment for acute myelogenous leukemia.

Supportive care is a prerequisite for intensive chemotherapy in leukemic patients. Little has been published about quantitative aspects of red blood cell and platelet transfusions. We evaluated transfusion requirements and factors associated with observed differences in 206 patients undergoing initial induction consolidation chemotherapy for newly diagnosed acute myelogenous leukemia. All patients were treated during a 5-year period in 12 hospitals on a common protocol of the Swiss Study Group for Clinical Cancer Research (SAKK). Protocol 30/85 comprises a double induction and one course of consolidation. Of 206 registered patients, 199 were evaluable; 118 of 199 (59%) patients entered completed all three cycles of chemotherapy. These 118 patients received a median (range) of 18 (3-44) units of red blood cells and 12 (2-61) platelet transfusions during 112 (70-129) days of hospitalization. Patients with a hemoglobin > 10 g/l, platelets > 100 x 10(9)/l, and white blood cell counts < 5 x 10(9)/l at diagnosis received fewer transfusions than patients with less favorable blood counts during the first cycle of chemotherapy (p < 0.05). Patients with FAB subtype M3 received more platelet transfusions during the first cycle. Female patients received more platelet transfusions than male patients. In multivariate analyses the participating center was the most important single factor associated with the number of red cell and platelet concentrates given per patient and cycle (p < 0.05), the number of days in hospital (p < 0.05), and the risk of premature withdrawal from the study. These data define factors associated with transfusion requirements in patients treated for newly diagnosed AML. They include severity and subtype of disease at diagnosis, age and sex of the patients, and the participating institution. Results suggest that medical decision-making varies from center to center. The participating institution is strongly associated with differences in transfusion requirements, hospitalization time, and premature withdrawal from study. Leukemia trials tend to focus on the prospective evaluation of chemotherapy or growth factors. Our results suggest that other variables, such as management strategies, should be included for prospective analysis.

Adolescent↗
PubMed1993

Evidence for up-regulated low density lipoprotein receptor in human lung adenocarcinoma cell line A549.

Human lung adenocarcinoma cell line A549 was studied with respect to the metabolism of human low density lipoprotein (LDL) and 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGR) activity. After incubation in medium containing lipoprotein-deficient serum (LPDS) for 24 h, the A549 cell line expresses a single class of high affinity LDL binding sites (KD at 37 degrees C of 15.1 +/- 0.7 nM and capacity of 118 +/- 2.8 ng/mg cell protein) and an HMGR activity of 111.4 +/- 7 pmol/min/mg cell protein. After binding, the LDLs were internalized and degraded by a common saturable process. The HMGR activity was higher in A549 cells than in fibroblasts but LDL affinity and binding capacity were similar in both cell types. However, in the presence of lipoproteins, A549 cells showed a two-fold higher binding capacity than fibroblasts. When the cells were deprived of cholesterol, the amount of LDLR sites increased but the extent of stimulation was lower in A549 than in fibroblast cells (2.5-fold versus six-fold respectively). This increase was accompanied by a similar increase in the specific LDLR mRNA cellular levels (two-fold versus six-fold respectively). When cells were deprived of exogenous and endogenous cholesterol (biosynthesis blocked by compactin), the binding capacity and the LDLR mRNA levels were yet again increased in A549 cells but not in fibroblasts. Taken together these results suggest that the level of expression of the LDLR is up-regulated in A549 cells compared to fibroblasts.

Adenocarcinoma↗
PubMed1993

Low density lipoprotein for cytotoxic drug targeting: improved activity of elliptinium derivative against B16 melanoma in mice.

Significant low density lipoprotein (LDL) uptake by tumour cells led to the use of LDL as a discriminatory vehicle for the delivery of cytotoxic drugs. In the current study, the lipophilic elliptinium derivative, elliptinium-oleate (OL-NME), was incorporated into LDL to reach an incorporation level of 400 molecules per LDL particle. The OL-NME-LDL complex showed cytotoxic effects on normal human fibroblasts while the cytotoxicity was not observed on receptor-defective human fibroblasts, indicating the ability of the complex to be preferentially metabolised by the LDL receptor. In vivo metabolism of the complex was related to the LDL receptor pathway. The metabolic clearance was the same for native LDL (17.1 ml h-1) and OL-NME-LDL complex (16.2 ml h-1). LDL incorporated OL-NME enhanced the anti-tumour activity against murine B16 melanoma model; this resulted from increased efficacy for OL-NME-LDL at doses equal to free 9-OH-NME (157 vs 76 of Increase Life Span (ILS) (%) values after intraperitoneal (i.p.) drug injection on i.p. implanted tumour model and 45 vs -2 ILS (%) values after intravenous drug injection on subcutaneous implanted tumour model). These data suggest that LDL improves the potency of lipophilic cytotoxic drugs against tumours that express LDL receptor activity.

Animals↗
PubMed1993

High density lipoprotein3 binding sites are related to DNA biosynthesis in the adenocarcinoma cell line A549.

The effect of high density (apoE-depleted HDL3) on cell growth of a human tumor cell line (A549) was studied and related to its binding on the plasma membrane. HDL3 were shown to stimulate the incorporation of [3H]thymidine into DNA and cell proliferation; these effects were dose-dependent. As HDL3, apoA-I and apoA-I-liposomes complexes (but not apoA-II) were able to stimulate DNA synthesis in serum-free conditions. This effect was maximum for 15-30 micrograms HDL3 protein/ml concentration. Binding of HDL3 on whole cells occurred by two mechanisms: the first was specific for HDL3; the second, of lower affinity, was phospholipid-dependent and was inhibited by low density lipoprotein or by phospholipid particles. Internalization and degradation of bound HDL3 were not observed. The specific sites (27.9 +/- 2.2 ng HDL3 protein/ng cell protein) accounted for only 2.5% of total (specific+phospholipid) binding sites and they bound HDL3 with a dissociation constant (KD) of 2.47 +/- 0.46 microgram HDL3 protein/ml (2.6 +/- 0.5 x 10(-8) M). The apparent KD value of total binding sites (specific+phospholipid) was eightfold higher (20.4 +/- 6.1 micrograms HDL3 protein/ml). Analysis of the membrane specific binding sites by ligand blotting with 125I-labeled HDL3 showed a single protein with an apparent molecular mass of 110 kDa. When HDL3 binding on phospholipid sites was inhibited by rigid phospholipid particles, the stimulation of [3H]thymidine incorporation related to HDL3 concentration did not show a maximum peak as previously observed but reached a plateau at a concentration as low as 5 micrograms HDL3 protein/ml. This low concentration also nearly saturated the specific binding sites with HDL3. When binding on specific protein sites was suppressed by tetranitromethane, DNA synthesis was not stimulated but, in contrast, inhibited. The stimulating effect of HDL3 on DNA biosynthesis is therefore likely dependent on HDL3 occupying specific binding sites.

Adenocarcinoma↗
PubMed1992

Low-density lipoprotein for delivery of an acrylophenone antineoplastic molecule into malignant cells.

In vitro and in vivo data have indicated that tumor cells actively internalize the low-density lipoprotein (LDL) from the circulation. A family of 2-(aminomethyl) acrylophenones (AMA) possesses an in vitro antileukemic activity but is devoid of any in vivo antineoplastic activity, because the compounds are actively captured by proteins in solution in the blood. In order to achieve a selective delivery of these drugs via the LDL pathway, we have incorporated an AMA drug, 2-morpholinomethyl-2',3',4'- trimethoxy acrylophenone hydrochloride (ILE) into LDL particles. ILE spontaneously associated with LDL to produce an LDL-ILE complex containing 200 +/- 100 molecules of drug per LDL particle. The LDL-ILE complex was highly electronegative as detected by electrophoresis. Further, this complex presented an immunologically detected over expression of the ligand-binding domain to the LDL receptor. In spite of these modifications, the LDL receptor processing bound, internalized, and degraded the LDL-ILE complex. Nevertheless, these biological properties were reduced by 32, 20, and 40%, respectively, in comparison to native LDL. Despite its high electronegativity, the LDL-ILE complex was not recognized by the macrophagic scavenger receptor. The LDL-ILE complex showed specific LDL receptor mediated in vitro cytotoxicity as judged from the growth inhibition of neoplastic A549 cells and of normal fibroblasts, but no activity on defective LDL receptor cells. Further, the pharmacological activity of the complex against A549 cells has been demonstrated to be equally potent as that of the free drug (median inhibitory dose, 5 microM). It is suggested that LDL drug targeting of AMA molecules could specifically deliver active molecules to cancer cells, avoiding their entrapment by other blood proteins and their rapid clearance by the reticuloendothelial system.

Antibodies, Monoclonal↗