Nitric Oxide Affects Heme Oxygenase-1, Hepcidin, and Transferrin Receptor Expression in the Placenta

Nitric oxide (NO) is a gasotransmitter that avidly binds both free and heme-bound iron, forming relatively stable iron nitrosyl compounds (FeNOs). We have previously demonstrated that FeNOs are present in the human placenta and are elevated in preeclampsia and intrauterine growth restriction. The ability of NO to sequester iron raises the possibility of the NO-mediated disruption of iron homeostasis in the placenta. In this work, we tested whether exposure of placental syncytiotrophoblasts or villous tissue explants to sub-cytotoxic concentrations of NO would elicit the formation of FeNOs. Furthermore, we measured changes in the mRNA and protein expression levels of key iron regulatory genes in response to NO exposure. Ozone-based chemiluminescence was used to measure concentrations of NO and its metabolites. Our results showed a significant increase in FeNO levels in placental cells and explants treated with NO (p < 0.0001). The mRNA and protein levels of HO-1 were significantly increased in both cultured syncytiotrophoblasts and villous tissue explants (p < 0.01), and the mRNA levels of hepcidin and transferrin receptor were significantly increased in culture syncytiotrophoblasts and villous tissue explants, respectively, (p < 0.01), while no changes were seen in the expression levels of divalent metal transporter-1 or ferroportin. These results suggest a potential role for NO in iron homeostasis in the human placenta and could be relevant for disorders of pregnancy such as fetal growth restriction and preeclampsia.

Iron nitrosyl complexes are formed from nitrite in the human placenta

Placental nitric oxide (NO) is critical for maintaining perfusion in the maternal-fetal-placental circulation during normal pregnancy. NO and its many metabolites are also increased in pregnancies complicated by maternal inflammation such as preeclampsia, fetal growth restriction, gestational diabetes, and bacterial infection. However, it is unclear how increased levels of NO or its metabolites affect placental function, or how the placenta deals with excessive levels of NO or its metabolites. Since there is uncertainty over the direction of change in plasma levels of NO metabolites in preeclampsia, we measured the levels of these metabolites at the placental tissue level. We found that NO metabolites are increased in placentas from patients with preeclampsia compared to healthy controls. We also discovered by ozone-based chemiluminescence and electron paramagnetic resonance that nitrite is efficiently converted into iron nitrosyl complexes (FeNOs) within the human placenta, and also observed the existence of endogenous FeNOs within placentas from sheep and rats. We show these nitrite-derived FeNOs are relatively short-lived, predominantly protein-bound, heme-iron nitrosyl complexes. The efficient formation of FeNOs from nitrite in the human placenta hints towards the importance of both nitrite and iron nitrosyl complexes in placental physiology or pathology. As iron nitrosylation is an important post-translational modification that affects the activity of multiple iron-containing proteins such as those in the electron transport chain, or those involved in epigenetic regulation, we conclude that FeNOs merit increased study in pregnancy complications.

A multicentre phase I and pharmacokinetic study of BN80915 (diflomotecan) administered daily as a 20-min intravenous infusion for 5 days every 3 weeks to patients with advanced solid tumours

BACKGROUND

BN80915 (diflomotecan) is an E-ring modified camptothecin analogue, which possesses greater lactone stability in plasma compared with other topoisomerase I inhibitors. This phase I study was carried out using a daily times five administration schedule (dx5) repeated three weekly. The primary objective was to determine the maximum tolerated dose (MTD) and recommended dose (RD) for phase II studies. Secondary objectives were to determine the safety and pharmacokinetic (PK) profile, and to make a preliminary assessment of antitumour activity.

PATIENTS AND METHODS

Diflomotecan was administered intravenously on days 1-5 every 3 weeks. Patients were treated in cohorts of three to six per dose level and the dose of diflomotecan was escalated according to modified Fibonacci schedule. Plasma concentrations of diflomotecan and its metabolite BN80942 were quantified.

RESULTS

Thirty patients were assessable for toxicity. Dose levels explored were 0.05, 0.1, 0.125 and 0.15 mg/m(2)/day. The 0.15-mg/m(2) dose level was determined to be the MTD. Toxicity was acceptable at the 0.125-mg/m(2)/day dose level. PK analysis showed the principal parameters were neither time nor dose dependent. There was a wide interpatient variability in PK at all dose levels. One patient with colorectal cancer, previously treated with irinotecan, had a partial response. A further eight patients had disease stabilisation.

CONCLUSIONS

The MTD and RD of diflomotecan administered according to a dx5 repeated three weekly are 0.15 and 0.125 mg/m(2)/day, respectively. In general, treatment was well tolerated; the principal toxicity was reversible myelosuppression. An objective response was seen in a patient previously treated with irinotecan.

Flow cytometric monitoring of anthracycline accumulation after anti-neoplastic ether phospholipid treatment

Ether phospholipids are new anti-neoplastic drugs that have been found active against a variety of tumor cell lines, including drug-resistant sublines. We have characterized the antiproliferative activity of three ether phospholipids, i.e. ET-18-OCH3 (Edelfosine), BM 41.440 (limofosine) and a new aza-derivative (BN 52205), on three leukemic cell lines, i.e. K562 (chronic myeloid leukemia, blast crisis), HL60 (promyelocytic acute leukemia) and CEM (T cell leukemia), and their respective drug-resistant sublines, i.e. K562-ADR (adryamicin resistant), HL60-DNR [daunorubicin (DNR) resistant] and CEM-VLB (vinblastin resistant). These resistant sublines have been found to express the multidrug-resistant phenotype, revealed by the presence of the P-glycoprotein (PgP) using different monoclonal antibodies. Increased cellular accumulation of the fluorescent anthracycline has been found in both sensitive and resistant cell lines after different ether phospholipid treatment times. In resistant cells, the ether phospholipid effect on DNR accumulation has also been found after blocking the PgP function by verapamil and cyclosporin A. These results confirm that the ether phospholipid action is closely linked with the membrane biochemical composition and that these new anti-tumor drugs are able to change the dynamic structural organization of the tumor cell membrane.

The induction of apoptosis is a common feature of the cytotoxic action of ether-linked glycerophospholipids in human leukemic cells

The ability of 2 recent ether-lipid derivatives, aza-phospholipids BN52205 and BN52211, to induce apoptosis in different leukemia cell lines was investigated using I-octadecyl-2-methyl-rac-glycero-3- phosphocholine (ET-18-OCH3) as a positive control. HL60, K562, Molt-4 and U937 cells were exposed for 24 hr to 20 microM of drug. The 2 aza-derivatives were as cytotoxic as ET-18-OCH3: BN52205 and BN52211 selectively induced apoptotic death in HL60, Molt-4 and U937 cells, but not in the K562-resistant cell line. Around 50% of DNA was fragmented in HL60 cells after exposure to the aza-derivatives, and 34% and 20% of DNA was fragmented in Molt-4 and U937 cells respectively. Similar results were obtained when cells were exposed to ET-18-OCH3. Our data confirm that ether lipids induce apoptosis in a variety of human leukemic cells, providing a possible explanation for their selectivity and mechanism of action.

New antineoplastic aza-phospholipids - synthesis, in-vitro cytotoxicity and differential cellular-sensitivity against 70 human tumor-cell lines

The in vitro cytotoxicity and differential cellular sensitivity of three new synthetic anti-neoplastic aza-phospholipids has been determined in the National Cancer Institute's (NCI) primary antitumor drug screen. Based on a disease-oriented strategy, this screen incorporates seventy human cell lines representing leukemia, ovarian, brain, melanoma, colon, renal, lung, prostate and breast cancers. The analysis of the GI50 values obtained for each aza-derivative has revealed a differential cellular sensitivity among the cell lines examined. The study of the degree of differential growth inhibition has shown a statistically significant differential cell sensitivity for BN 52205 and BN 52211 for colon and melanoma tumor cells. The leukemia cell selectivity for BN 52211 was even more remarkable due to the low molar concentration at which the maximum selective effect occurred. These findings strongly encourage further investigations on the anti-neoplastic activity of aza-phospholipids.

Effect of paf antagonists on the cytotoxic activity of antineoplastic ether phospholipids

The capability of the methoxy-substituted 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-18-OCH3 or Edelfosine) and the two aza-alkylphospholipids BN 52205 and BN 52211 to bind to the PAF receptor was analysed in rabbit platelet membranes. Ether phospholipid concentrations were tested between 10(-5) M and 10(-11) M. The results indicate that ether phospholipids are not able to bind to the PAF receptor and do not prevent PAF binding to its receptor. Moreover, the cytotoxic effect of three potent PAF antagonists, BN 52021, BN 50730 and BN 50739, were analysed in HL60 promyelocytic cells. These cells were pre-and co-treated with PAF antagonists and ether phospholipids. The data show that the three PAF antagonists failed to counteract the activity of ET-18-OCH3, BN 52205 and BN 52211 thus demonstrating that the cytotoxic effect of these new anti-neoplastic drugs is not mediated by the PAF receptor.

Cytotoxic properties of a new synthetic demethylpodophyllotoxin derivative, BN 58705, against human tumor cell lines

The in vitro cytotoxic properties of a newly synthesized demethylpodophyllotoxin derivative, 4-o-butanoyl-4'-demethylpodophyllotoxin (BN 58705), were determined by using several human tumor cell lines of different histological origin and of different sensitivity to conventional chemotherapeutic drugs (Adriamycin and cis-diammine-dichloride platinum). BN 58705 is shown to be cytotoxic against various human tumor cell lines as assessed by the MTT assay. Furthermore, BN 58705 is shown to be cytotoxic against several drug-resistant tumor cell lines. BN 58705 is cytotoxic at concentrations 100- to 1000-fold lower than those of Adriamycin or cis-diammine-dichloride platinum required to achieve similar cytotoxicity. BN 58705 did not mediate DNA fragmentation of target cells, whereas the epipodophyllotoxin-like etoposide induced DNA cleavage by stabilizing the DNA-enzyme intermediate. Like vinca alkaloids, BN 58705 induced a block in the mitotic phase of the cell cycle. By comparison, BN 58705 exerted a stronger cytotoxic activity in vitro than did either etoposide, an epipodophyllotoxin, or vincristine, a vinca alkaloid. When BN 58705 was applied in vivo in mice, it resulted in low toxicity (50% lethal dose, 150 mg/kg). These results demonstrate than BN 58705 is cytotoxic to drug-resistant human tumor cell lines and is manyfold more potent than conventional drugs. The cytotoxic potency and low toxicity of BN 58705 are important criteria to establish its potential chemotherapeutic efficacy in vivo.

Evaluation of combinations of antineoplastic ether phospholipids and chemotherapeutic drugs

Combinations of drugs are used clinically for the therapeutic advantages they may provide over single agents. We have studied the cytotoxic interaction between four either phospholipids ET-18-OCH3, BM 41.440, BN 52205 and BN 52211, and several chemotherapeutic drugs (ADM, CDDP, VLB, VP-16, MMC, BLM and MTX) on two human tumor cell lines, A427 (lung) and HT29 (colon). We have used the MTT colorimetric assay to evaluate growth inhibition and performed isobologram analysis on the IC50 data. For both cell lines a synergistic effect has been found between each of the four ether phospholipids in association with CDDP and ADM. In both cell lines only BM 41.440 and BN 52211 act synergistically with VLB while, in A427 cells, only BN 52205 behaves similarly with MMC. These results show that a positive interaction exists between ether phospholipids, spindle poisons and DNA-interactive drugs.

Dactylocyclines, novel tetracycline derivatives produced by a Dactylosporangium sp. I. Taxonomy, production, isolation and biological activity

A screen for antibiotics with activity against tetracycline-resistant microorganisms has led to the isolation of Dactylosporangium sp. (ATCC 53693), a producer of several novel tetracycline derivatives. The major fermentation products, dactylocyclines A and B, were purified and MIC values determined against tetracycline-resistant and tetracycline-sensitive Gram-positive bacteria. The dactylocyclines represent the first naturally occurring tetracycline C2 amides which lack cross resistance with tetracycline.

Membrane cholesterol content and sensitivity of human carcinoma-cells to antineoplastic ether phospholipids

Ether phospholipids represent a new class of anti-cancer drugs which appear to exert their tumoricidal activity through a direct and indirect cytotoxic effect against tumor cells of different origins. The chemotherapeutic interest in these new drugs is based on the finding that, contrary to the majority of anti-cancer drugs, ether phospholipids do not interfere with DNA synthesis, are anti-invasive and induce tumor cell differentiation. There is increasing experimental evidence that the direct cytotoxic effect of these new drugs is mediated by the cell membrane. We have measured the lipid membrane composition of three human carcinoma cell lines that have been found to possess different sensitivity to the tumoricidal activity of four antitumor ether phospholipids. A statistically significant difference has been found in the membrane cholesterol content of the three cell lines and a positive correlation has been established between the membrane cholesterol level and the carcinoma cell sensitivity to ether phospholipids. These findings emphasize previous data obtained with leukemic cells and reinforce the interest in ether phospholipids whose cytotoxic properties may represent a new step towards a more promising anti-cancer chemotherapy.

Cytostatic activity of new synthetic anti-tumor aza-alkyllysophospholipids

Alkyllysophospholipids are analogues of the naturally occurring 2-lysophosphatidylcholine which have been reported to have selective in vitro/in vivo anti-tumor activity. Their antiproliferative effect has been found against a variety of animal and human tumor cell lines. We have characterized the cytostatic activity of 2 newly synthetized aza-alkyllysophospholipids (AALPs), the BN52205 and the BN52211, on a human tumor cell line derived from a colon adenocarcinoma, the HT29. We used 3 different flow cytometric approaches to study which phase of the cell cycle was the most sensitive to the antiproliferative activity of the 2 AALPs. By applying the biparametric analysis of 5'-bromo-2-deoxyuridine incorporation vs. DNA content we have been able to demonstrate that the 2 AALPs do not interfere with the S phase of the cell cycle. The simultaneous measurement of total nuclear protein vs. DNA content in isolated HT29 nuclei enabled us to exclude a block in the M phase of the cell cycle. Finally, stathmokinetic analysis enabled us to show that cytostatic activity of the 2 new AALPs is characterized by multiple "terminal points" as the drugs' action results in a G1 block, in a slow-down of the transition from late S to G2 followed by an accumulation of HT29 cells in the G2 phase of the cell cycle.

Tumor cell kinetics following antineoplastic ether phospholipid treatment

Ether phospholipids are analogues of the naturally occurring 2-lyso-phosphatidylcholine that have been reported to have in vitro/in vivo antitumor activity. Their antiproliferative effect has been found against a variety of animal and human tumor cell lines. We have characterized the cytostatic activity of two ether phospholipids, 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine and 1-hexadecylmercapto-2-methoxymethyl-rac-glycero-3-phosphocholine, on a human tumor cell line derived from a colon adenocarcinoma, HT29. We have used three different flow cytometric approaches to study which phase of the cell cycle was the most sensitive to the antiproliferative activity of the two ether phospholipids. By applying the biparametric analysis, 5'-bromo-2-deoxyuridine incorporation versus DNA content, we have been able to demonstrate that ether phospholipids do not interfere with the S phase of the cell cycle. The simultaneous measurement of total nuclear protein versus DNA content in isolated HT29 nuclei has enabled us to exclude a block in the M phase of the cell cycle. Finally, the stathmokinetic analysis has allowed us to show that the cytostatic activity of the two ether phospholipids 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine and 1-hexadecylmercapto-2-methoxymethyl-rac-glycero-3-phosphocholine is characterized by multiple "terminal points" as the drugs action results in a G1 block and in a slow-down of the transition from late S to G2, followed by an accumulation of HT29 cells in the G2 phase of the cell cycle.

Cytotoxic activity of synthetic aza alkyl lysophospholipids against drug sensitive and drug resistant human tumor cell lines

The anti-tumor cytotoxic activity of four newly synthesized aza alkyl lysophospholipids (AALP), namely BN 52205, BN 52207, BN 52208 and BN 52211, was investigated. Using the 51Cr release assay, the four compounds were endowed with cytotoxic activity, in a concentration-dependent fashion, against various human tumor cell lines of different histological origin. Two different mechanisms appear to be involved in the AALP-mediated cytotoxicity. A rapid membrane damaging effect was observed in less than one hour's incubation of tumor cells with AALP and cytotoxicity was temperature-independent when AALP were used at greater than or equal to 200 micrograms/ml. A slower cytotoxic mechanism was observed after 18 hours incubation at 37 degrees C when AALP were used at concentrations of 30-100 micrograms/ml. The pattern and magnitube of the cytotoxic activity achieved with all the 4 AALP compounds tested were similar and the cytotoxicity mediated by combination of two compounds was additive. In addition to the cytotoxic effect, the AALP compounds also exerted a cytostatic anti-tumor effect, as assessed by inhibition of 3H TdR incorporation. Using a variety of human tumor cell lines as targets, the cytotoxic effect observed with the AALP was noted with tumor cells that were either sensitive or resistant to TNF-alpha and/or chemotherapeutic drugs such as mitomycin C, adriamycin and cis-platinum. The LD50 toxicity in mice was 100-125 mg/kg. The present findings demonstrate that AALP are cytotoxic to a variety of human tumor cell lines and do not appear to discriminate between drug/cytokine sensitive or resistant cells. Thus the present study suggests that some aza alkyl lysophospholipids may be considered as potential anticancer agents.

Cellular thiols in rat liver cell lines possessing different growth characteristics

Thiol levels were measured in three cell lines derived from rat hepatocytes with different growth rates and degrees of tumorigenicity: IAR20 having normal epithelial morphology and no tumour forming ability; IAR6.1 being a chemically-transformed malignant cell line; and IAR6.1RT7 derived from an epithelial tumour obtained after injection of IAR6.1 cells into a syngenic animal. The mean levels of GSH, GSSG, low molecular weight thiols (LMWT), macromolecular thiols (MT) and total reactive protein sulphur (TRPS), expressed as nmoles-SH mg-1 protein, were found to be 25.5, 7.5, 50.1, 114.5 and 143.6 respectively for IAR20; 37.6, 3.9, 65.4, 126.8 and 148.4 for IAR6.1; 17.2, 4.4, 52.3, 141.0 and 168.2 for IAR6.1RT7. Cultures were treated with D,L-buthionine-S,R-sulphoximine (BSO) to cause greater than 70 per cent depletion of GSH and the measurements of cellular thiols repeated. Although treatment with BSO caused a substantive decrease in the LMWT fraction, there were no major changes in macromolecular thiols or in total reactive protein sulphur. The respective mean values for LMWT, MT and TRPS (expressed as nmoles-SH mg-1 protein) were 19.4, 109.8, 136.3 for IAR20; 17.2, 119.3, 143.6 for IAR6.1; 21.6, 150.7 and 163.5 for IAR6.1RT7. It is concluded that significant differences in thiol levels exist between the three rat liver cell lines studied. However, severe acute depletion of GSH is not reflected by changes in the levels of macromolecular thiols which suggests that there is only a slow equilibrium between these two major thiol pools.

In vitro transformation induces abnormal protein thiol levels in rat liver cells

Cells from an established line of normal rat hepatocytes (IAR 20) were irradiated with 3 Gy gamma-radiation from a cobalt source to generate transformed clones. Cells from four transformed colonies were compared with the parent cell line by flow cytometry following staining with ortho-phthalaldehyde and propidium iodide to quantitate protein thiols and DNA respectively. Transformed cells exhibited an increased variability in cellular protein thiols which was most evident in G1 and S phase. The altered pattern of macromolecular thiol distribution implies early changes in redox state and/or modification of the amounts or types of sulphur-containing proteins in transformed cells.

Platelet-activating factor antagonist, BN-52021 protects against cis-diamminedichloroplatinum nephrotoxicity in the rat

The protective effect of the platelet-activating factor (PAF) antagonist, BN 52021, was assessed on cis-diammine-dichloroplatinum (CDDP)-induced nephrotoxicity. Wistar male rats were treated with either a single dose of CDDP (10 mg/kg b.w. ip) alone or in association with 7 daily doses of BN 52021 (10 mg/kg b.w. ip). At the end of the experiment, the CDDP-treated rats lost 25% of body weight and serum creatinine and urea increased from 0.041 +/- 0.006 mmol/l and 0.165 +/- 0.007 g/l for the control group to 0.202 +/- 0.019 mmol/l and 1.51 +/- 0.131 g/l versus CDDP respectively. Body weight, serum creatinine, serum urea and creatinine clearances were similar to the control group in animals treated with CDDP and BN 52021. CDDP caused proximal tubular necrosis and dilatation of cortical collecting tubes, changes that were markedly less in the BN 52021-protected animals. The concomitant administration of BN 52021 with CDDP did not modify the plasma pharmacokinetic of CDDP. In addition, BN 52021 did not interfere with the antiproliferative and antitumoral actions of CDDP in cultured human tumor cells. BN 52021 therefore could prevent the nephrotoxicity of CDDP.

Flow cytometric analysis of protein thiol groups in relation to the cell cycle and the intracellular content of glutathione in rat hepatocytes

The relationship between protein thiols (PSH) and cell proliferation was examined in ethanol-fixed rat hepatocytes. A new protocol was developed for simultaneous measurement of protein thiol vs. DNA content by flow cytometry. The fluorescent dye o-phthalaldehyde (OPT) was used for flow cytometric measurements of protein thiol groups. The influence of nonprotein thiols was examined by monitoring the cell cycle of cells in which the glutathione content (GSH) was modified by treatment with buthionine sulphoximine (BSO). Three rat liver cell lines (IAR 20, IAR 6.1, IAR 6.1RT7) were used: these cell lines possess different growth characteristics and degrees of tumorigenicity, which made it possible to analyse changes in PSH during normal and deranged cell proliferation. The effects on the cell cycle of the changes in PSH due to the depletion of GSH were measured by 5-bromo-2'-deoxyuridine (BrdUrd) incorporation and flow cytometry. The data obtained can be summarised as follows: a) OPT fluorescence increases with increasing DNA content in all rat liver cell lines examined; b) the greatest variation in PSH content occurs in G1. There is a smaller variation in G2 + M, and PSH levels are relatively invariant throughout S-phase; c) a higher content of PSH is found in the tumorigenic cell lines; d) the amount and distribution of PSH is not affected by BSO treatment; e) kinetic studies indicate that BSO treatment has no effect on the ability of the IAR rat liver cell lines to progress through the cycle.

Respiratory responses to pirenzepine in healthy subjects

Since no information is available concerning the action of pirenzepine in vivo on human tracheobronchial tree, we evaluated the respiratory responses to pirenzepine in a group of healthy subjects. This clinical study suggests that pirenzepine exerts its bronchodilatory action on small airways (from 9th generation to distal airways), but not on larger airways, in normal subjects. These results are consistent with a probable presence of muscarinic high affinity receptors (M1 subtype) only in peripheral airways.

The induction of forward gene mutation and gene conversion in yeasts by treatment with cyclophosphamide in vitro and in vivo

The present paper assesses the most suitable conditions for metabolic activation with yeasts in vitro, at least as far as cyclophosphamide (Cy) is concerned. These include treatment time, incubation temperature, the amounts of S9 and cofactors. Particular attention is devoted to the use of various solvents, showing that their use can considerably affect the mutagenic response of the chemical being tested. It also examines the effects of enzyme inducers (by using S9 from rats and mice) such as phenobarbital (PB) and 5,6-benzoflavone (BF) administered separately or together. The metabolizing capability of other organs such as the lungs and kidneys is also determined. All these data are compared with Cy genotoxicity (in vivo) evaluated by the intrasanguineous host-mediated assay and by recovering the yeast target cells from the liver, lung and kidneys. The most striking effects are that, in vitro, PB greatly enhances Cy genotoxicity, whilst in vivo it substantially reduces it.