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Objectives: Polyamines are organic polycations playing an essential role in cell proliferation and differentiation, as well as in cell contractility, migration and apoptosis. These processes are known to contribute to restenosis, a pathophysiological process often occurring in patients submitted to revascularization procedures. We aimed to test the effect of alpha-difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase, on vascular cell pathophysiology in vitro and in a rat model of carotid arteriotomy-induced (re) stenosis. Methods: The effect of DFMO on primary rat smooth muscle cells (SMCs) and mouse microvascular bEnd. 3 endothelial cells (ECs) was evaluated through the analysis of DNA synthesis, polyamine concentration, cell viability, cell cycle phase distribution and by RT-PCR targeting cyclins and genes belonging to the polyamine pathway. The effect of DFMO was then evaluated in arteriotomy-injured rat carotids through the analysis of cell proliferation and apoptosis, RT-PCR and immunohistochemical analysis of differential gene expression. Results: DFMO showed a differential effect on SMCs and on ECs, with a marked, sustained anti-proliferative effect of DFMO at 3 and 8 days of treatment on SMCs and a less pronounced, late effect on bEnd. 3 ECs at 8 days of DFMO treatment. DFMO applied perivascularly in pluronic gel at arteriotomy site reduced subsequent cell proliferation and preserved smooth muscle differentiation without affecting the endothelial coverage. Lumen area in DFMO-treated carotids was 49% greater than in control arteries 4 weeks after injury. Conclusions: Our data support the key role of polyamines in restenosis and suggest a novel therapeutic approach for this pathophysiological process. (C) 2013 Elsevier Ireland Ltd. All rights reserved.

Background: Mononuclear platinum anticancer agents hold a pivotal place in the treatment of many forms of cancers, however, there is a potential to improve response to evade resistance development and toxic side effects. BBR3464 is a promising trinuclear platinum anticancer agent, which is a polyamine mimic. The aim was to investigate the influence of polyamine pool reduction on the cytotoxic effects of the trinuclear platinum complex BBR3464 and cisplatin. Polyamine pool reduction was achieved by treating cells with either the polyamine biosynthesis inhibitor alpha-difluoromethylornithine (DFMO) or the polyamine analogue N-1,N-11-diethylnorspermine (DENSPM). Methods: A human squamous cell carcinoma cell line, LU-HNSCC-4, established from a primary head and neck tumour was used to evaluate cellular effects of each drug alone or combinations thereof. High-performance liquid-chromatography was used to quantify intracellular polyamine contents. Inductively coupled mass spectroscopy was used to quantify intracellular platinum uptake. Cells were exposed to DFMO or DENSPM during 48 h at concentrations ranging from 0 to 5 mM or 0 to 10 mu M, respectively. Thereafter, non-treated and treated cells were exposed to cisplatin or BBR3464 during 1 h at concentrations ranging from 0 to 100 mu M. A 96-well assay was used to determine cytotoxicity after five days after treatment. Results: The cytotoxic effect of BBR3464 on LU-HNSCC-4 cells was increased after cells were pre-treated with DENSPM or DFMO, and the interaction was found to be synergistic. In contrast, the interaction between cisplatin and DFMO or DENSPM was near-additive to antagonistic. The intracellular levels of the polyamines putrescine and spermidine were decreased after treatment with DFMO, and treatment with DENSPM resulted in an increase in putrescine level and concomitant decrease in spermidine and spermine levels. The uptake of BBR3464 was significantly increased after pre-treatment of the cells with DFMO, and

New drugs are urgently needed for the treatment of tropical and subtropical parasitic diseases, such as African sleeping sickness. Chagas' disease, leishmaniasis and malaria. Enzymes in polyamine biosynthesis and thiol metabolism, as well as polyamine transporters, are potential drug targets within these organisms. In the present review, the current knowledge of unique properties of polyamine metabolism in these parasites is outlined. These properties include prozyme regulation of AdoMetDC (S-adenosylmethionine decarboxylase) activity in trypanosomatids, co-expression of ODC (ornithine decarboxylase) and AdoMetDC activities in a single protein in plasmodia, and formation of trypanothione, a unique compound linking polyamine and thiol metabolism in trypanosomatids. Particularly interesting features within polyamine metabolism in these parasites are highlighted for their potential in selective therapeutic strategies.

We assessed the ototoxicity associated with oral alpha-difluoromethylornithine (DFMO) administration in 58 patients with metastatic malignant melanoma. One hundred seventy-nine sequential audiograms obtained from patients treated with DFMO alone (16 patients) or in combination with alpha 2b-interferon (42 patients) were evaluated. DFMO doses ranged from 2 to 12 g/m2/d and were given over periods of 2 to 50 weeks. Total doses ranging from 60 g/m2 to 1390 g/m2 were correlated with clinical effects and pure tone audiometric changes. By regression analysis cumulative DFMO dose showed a consistent and statistically significant positive relationship to hearing loss at multiple frequencies (500, 1000, 2000, 4000, and 8000 Hz). Patients with normal (threshold less than 30 db) baseline audiograms demonstrated more hearing loss than those with abnormal (threshold greater than or equal to 30 db) baseline audiograms at the higher frequency levels. Of the patients with normal prestudy hearing thresholds 10% or less developed a demonstrable hearing deficit at cumulative DFMO doses below 150 g/m2. Conversely, up to 75% of the patients who received more than 250 g/m2 developed a clinically demonstrable hearing loss. Other factors which adversely affected hearing included age, male gender, and the concomitant use of alpha 2b-interferon. In summary, the risk of clinically significant hearing loss in patients treated with DFMO was primarily related to dose and the presence of a pre-existing hearing deficit.

We assessed the ototoxicity associated with oral alpha-difluoromethylornithine (DFMO) administration in 58 patients with metastatic malignant melanoma. One hundred seventy-nine sequential audiograms obtained from patients treated with DFMO alone (16 patients) or in combination with alpha 2b-interferon (42 patients) were evaluated. DFMO doses ranged from 2 to 12 g/m2/d and were given over periods of 2 to 50 weeks. Total doses ranging from 60 g/m2 to 1390 g/m2 were correlated with clinical effects and pure tone audiometric changes. By regression analysis cumulative DFMO dose showed a consistent and statistically significant positive relationship to hearing loss at multiple frequencies (500, 1000, 2000, 4000, and 8000 Hz). Patients with normal (threshold less than 30 db) baseline audiograms demonstrated more hearing loss than those with abnormal (threshold greater than or equal to 30 db) baseline audiograms at the higher frequency levels. Of the patients with normal prestudy hearing thresholds 10% or less developed a demonstrable hearing deficit at cumulative DFMO doses below 150 g/m2. Conversely, up to 75% of the patients who received more than 250 g/m2 developed a clinically demonstrable hearing loss. Other factors which adversely affected hearing included age, male gender, and the concomitant use of alpha 2b-interferon. In summary, the risk of clinically significant hearing loss in patients treated with DFMO was primarily related to dose and the presence of a pre-existing hearing deficit.