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R Havouis

Publications and source records attributed to R Havouis.

At least 37 records · Page 2Linked to original sources
PubMed1992

Depletion in nuclear spermine during human spermatogenesis, a natural process of cell differentiation.

Polyamines (PA), polycations present in all mammalian cells, are essential for cell proliferation and differentiation. In vitro, PA are known to bind to DNA with a high affinity. In vivo, the intimate association of endogenous PA with highly condensed chromatin has been reported. During spermatogenesis, when processes of cell proliferation and differentiation take place, the potential role of polyamines has not been studied in depth. We report here the PA levels measured in human spermatogenic cell nuclei at different stages of differentiation. Cell populations (spermatocytes and round, elongating, or elongated spermatids) were obtained after submitting human testes to a trypsin-deoxyribonuclease digestion, then to a centrifugal elutriation and Percoll gradient centrifugation. A significant and progressive nuclear spermine level decrease was observed from primary spermatocytes to elongated spermatids. This release of spermine from nuclei was concomitant with three major events in mammalian spermiogenesis: the reduction of DNA transcription activity, the replacement of histone proteins by protamines, and the compaction of chromatin. This is the first report arguing a release of nuclear spermine during an in vivo physiological cell differentiation process.

Cell Differentiation↗
PubMed1991

The growth of MAT-LyLu rat prostatic adenocarcinoma can be prevented in vivo by polyamine deprivation.

The combination of inhibitors of ornithine decarboxylase and polyamine oxidase, and of antibiotics suitable for the (partial) decontamination of the gastrointestinal tract, with a polyamine deficient diet, is responsible for the almost complete inhibition of the growth of MAT-LyLu prostatic adenocarcinoma. In the tumor-bearing animals, erythrocyte spermidine levels were reduced, but spermine concentrations were increased. As has been previously observed, the increase in erythrocyte spermine level was associated with an enhancement of malignant cell death. Adriamycin administration did neither diminish tumor growth, nor potentiate the antitumor effect of polyamine deprivation treatment. Interruption of the polyamine deprivation treatment was accompanied by a significant enhancement of tumor growth. Since polyamine deprivation causes only reversible growth inhibition, it seems not appropriate as a monotherapy.

Adenocarcinoma↗
PubMed1990

Red blood cell polyamine level changes following heart transplantation in man.

Follow-up of orthotopic heart transplanted patients has revealed the existence of abnormally high red blood cell (RBC) spermidine (Spd) levels during the first two months after surgical procedure (A-period). From the third month after heart transplantation (B-period), RBC Spd concentrations went back to normal values in early cardiac rejection (ECR) patients. During A- and B-periods, significantly higher Spd levels and Spd/Spm ratios were observed in late cardiac rejecting (LCR) patients than in ECR ones. The lack of a direct relationship between the histological grade of rejection and RBC Spd levels leads us to consider these polyamine blood levels as a new biological instrument in the diagnosis of heart rejection.

Chromatography, High Pressure Liquid↗
PubMed1990

Erythrocyte polyamine levels in human prostatic carcinoma.

Abnormally high red blood cell polyamine levels were found in benign prostatic hyperplasia and in prostatic adenocarcinoma patients. In prostatic adenocarcinoma patients a relationship was noted between the importance of red blood cell spermidine and spermine concentrations, and the clinical stage of the disease (Whitmore classification). Considering prostatic adenocarcinoma patient populations, patients with metastases (groups 3 and 4) statistically differed from those without metastases (group 2). Furthermore, red blood cell polyamine level determination discriminated patients in the hormonal escape group (group 4) from those usually considered as hormone responsive (groups 2 and 3). No statistically significant correlation was observed between red blood cell polyamine levels and usual tumor markers (prostatic acid phosphatase and prostate specific antigen). These results confirmed that red blood cell polyamine levels must be considered as a circulating index of cell proliferation that might be of clinical importance during the long-term followup and treatment of prostatic adenocarcinoma patients.

Adenocarcinoma↗
PubMed1990

Mechanism of polyamine spermidine uptake by Xenopus laevis oocytes.

In this study, the mechanisms of polyamine spermidine (Spd) uptake were investigated in Xenopus laevis oocytes. Spd uptake followed a sigmoidal kinetics with [S]90/[S]10 = 3 microM and Hill interaction coefficient (n) = 2. The order of magnitude of uptake and efflux was similar (t1/2 = 45 min). The equilibrium potential for Spd, calculated by Nenrst equation, was 90.78 mV. Free energy change for the uptake (delta G) was found to be 2.31 Kcal/mole of Spd. During efflux, Spd was not converted into putrescine or spermine. It seems that there are two types of Spd uptake pathways: Na(+)-dependent and Na(+)-independent since replacement of Na+ from incubation medium did not completely abolish the Spd uptake. The Na(+)-dependent component of Spd uptake was shared neither by system A nor by system ASC amino acids.

Amino Acids↗
PubMedDate not supplied

Characterization of amine oxidase activities in macrophages from human peripheral blood.

A sensitive assay for the determination of hydrogen peroxide formation and a method for the identification and characterization of amine oxidases in cells and other oxidase sources of limited accessibility are described. The enzymes are characterized by substrate and inhibitor patterns. The method was applied to the identification and characterization of polyamine oxidizing enzymes in macrophages from human peripheral blood. The major oxidase activity in these cells was found to be a tissue-type polyamine oxidase, but with distinct characteristics. Diamine oxidase and monoamine oxidase activities were also detected in homogenates of macrophages. Since the formation of toxic products by a releasable polyamine oxidase is supposed to be an integral part of a regulatory function of macrophages, we consider our work as a basis for the elucidation of this function.

Amine Oxidase (Copper-Containing)↗
PubMedDate not supplied

Polyamines in human breast cancer and its relations to classical prognostic features: clinical implications.

Experimental evidence suggest an important role of polyamines in breast cancer development. Polyamines have been determined in tissue and erythrocyte samples from 100 patients with primary invasive breast cancer and 30 patients with fibroadenomas. Statistical analysis was performed in order to determine the prognostic value of the polyamine patterns of tumor tissues and erythrocytes in comparison with clinical and histological prognostic factors. In malignant tissues, polyamine levels were significantly higher than in benign tissues. They correlated with markers of tumor aggressivity (axillary node involvement and especially with markers of high mitotic rate as Ki-67 staining, histological grade). No correlation was found between estrogen and progesterone status, tumor size and polyamine concentrations. Erythrocyte polyamines levels were identical between cancer patients and controls. The knowledge of the polyamine pattern in breast cancer could become useful in clinical practice particularly if polyamine metabolism is targeted as a therapeutic approach.

Breast Neoplasms↗
PubMedDate not supplied

Benefits of complete polyamine deprivation in hormone responsive and hormone resistant MCF-7 human breast adenocarcinoma in vivo.

Polyamines are ubiquitous cellular compounds which are required for estradiol induced proliferation in breast cancer. Complete polyamine deprivation, using 2 alpha-difluoromethyl-ornithine (DFMO, Eflornithine), a specific inactivator of ornithine decarboxylase (key-enzyme of the polyamine biosynthesis) combined with inhibition of the bacterial production of gastrointestinal polyamine and a polyamine free regimen, was demonstrated to exhibit a cytostatic effect and a decrease of the three tumoral polyamine concentrations in a MCF-7 tumor model. In this experiment, complete polyamine deprivation has been tested on a standard MCF-7 tumor and on a variant MCF-7 tumor (i.e. with a tamoxifen acquired resistance). Polyamine deprivation was effective on the tumor growth, both on standard and variant sub-types. The polyamine contents of two types of tumor were similar, and identically, polyamine deprivation has caused a decrease of putrescine, spermidine and also spermine tumoral concentrations measured by the HPLC method in standard and variant MCF-7 tumors. Acquired tamoxifen resistance is common in patients undergoing hormonal therapy for advanced breast cancer. It has been hypothesized that the direct stimulation of polyamine pathway without estradiol involvement could be one of the mechanisms responsible for the tamoxifen resistance. The ability of polyamine deprivation to inhibit the growth of tumors becoming tamoxifen resistant could offer a therapeutic advantage in case of tumor with acquired tamoxifen resistance and could be tested to prevent or delay the hormonal responsiveness to breast cancer.

Adenocarcinoma↗
PubMedDate not supplied

Dimethylsilane polyamines: cytostatic compounds with potentials as anticancer drugs. II. Uptake and potential cytotoxic mechanisms.

Dimethylsilane tetramines are structural analogues of spermine with a (CH3)2 Si-group incorporated into the central carbon chain. They have potential as anticancer drugs. Their cytotoxic effect was considered to rely mainly on their polyamine antagonist property. In order to obtain new ideas about cellular mechanisms, which are potential targets of the dimethylsilane polyamines, the effects of these compounds on some basic cell functions, such as protein and DNA synthesis, and calmodulin antagonism were studied. In addition, their mode of accumulation in cells was investigated. It became evident that the intracellular accumulation of dimethylsilane polyamines is almost exclusively achieved via the polyamine transport system. However, the exchange of a part of the intracellular natural polyamines against dimethylsilane polyamines has only a small effect on polyamine uptake. Binding to the endoplasmic reticulum and inhibition of protein synthesis are presumably important for the cytotoxic action of bis(11-amino-4,8-diazaundecyl)dimethylsilane, a hexamine, but seem of no importance for the tetramines. Calmodulin antagonism, however, is likely to contribute to their cytotoxic effect.

Animals↗
PubMedDate not supplied

Protein kinase C inhibitor (H-7) potentiates antiproliferative effects of a polyamine biosynthesis inhibitor.

In this study, a protein kinase C inhibitor, H-7, was found to potentiate the antiproliferative effects of difluoromethyl ornithine (DFMO), inhibitor of the polyamine biosynthesis, on NIH 3T3 and 3T3/SV40 cells in culture. Incubation of the cells with DFMO inhibited the cell growth, whereas the addition of polyamine spermidine to these cells restored the normal rate of cell proliferation with the fact that these cells took up the polyamine from the extracellular medium to compensate the intracellular needs. The addition of H-7 to both the 3T3 and 3T3/SV40 cells, inhibited the cell proliferation, though the level of inhibition was always lower than in those treated with the DFMO alone. The addition of H-7 to the DFMO containing cells potentiated the antiproliferative effects of the latter with the fact that the former inhibited the uptake of the spermidine, though there might be additional targets, like the protein kinase C, involved in the inhibition process.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMedDate not supplied

Polyamine deprivation enhances antitumoral efficacy of chemotherapy.

We reported previously that polyamine deprivation by feeding a polyamine deficient diet combined with gastrointestinal tract decontamination and polyamine oxidase inhibition considerably enhanced the antitumoral effect of DFMO, a selective inhibitor of ornithine decarboxylase. The combination of polyamine deprivation and administration of well established cytotoxic drugs was expected to improve further the antitumoral effect of polyamine deprivation in Lewis lung carcinoma grafted in mice. Simultaneous treatment, i.e. administration of the cytotoxic drugs during the polyamine deprivation regimen, reduced tumor growth, but enhanced toxic effects. By alternating treatment and polyamine deprivation (1st day methotrexate (1.7 mg/kg), 2nd day cyclophosphamide (90 mg/kg), 3rd day vindesine (0.25 mg/kg), followed by five days of polyamine deprivation), tumor growth was reduced by 90% and an increase of 64% in the survival time of the animals was observed, demonstrating that a significant enhancement of the efficacy of chemotherapy was achieved without concomitant enhancement of toxic effects.

Animals↗
PubMedDate not supplied

Red blood cell polyamine evolution during normal growth in mouse.

Red blood cell (RBC) polyamine levels were studied at different ages in growing mice. Contrary to RBC from adult mice, high levels of the three polyamines Putrescine, Spermidine (Spd), Spermine (Spm) were detected in erythrocytes from newborn mice. These levels progressively decreased during growth. As previously reported in experimental and clinical studies related to tumor progression or normal tissue regeneration, a statistical correlation between Spd and Spm was noticed in this study concerning normal growth. As regards this correlation, two separate periods appeared during development. The slope values of the straight regression line were calculated for these periods and showed highly significant differences.

Aging↗
PubMedDate not supplied

Accumulation of polyamine analogs in red blood cells: a potential index of tumor proliferation rate.

It has previously been demonstrated that during Lewis lung carcinoma (3LL) growth, red blood cell (RBC) spermidine (Spd) levels change concominantly with the tumor volume and [14C] Spd accumulates in proportion with the tumor volume, if [14C] putrescine (Put) is administered. In the present study we substituted a non-radioactive analogue for labelled Put with the aim to perform human studies, should the method prove suitable to quantify malignant cell proliferation intensity. 2-Methylputrescine (2MPut) is an excellent substrate of spermidine synthase and is transformed in vivo into methylspermidine (MSpd) and 6-methylspermine (6MSpm). After a single i.p. dose of 2MPut, MSpd accumulated in RBC of mice with 3LL xenografts. The concentration of MSpd correlated directly with tumor progression. No significant amounts of MSpd were found in RBC of normal mice. It appears that 2MPut has the potential to become a new tool in tumor diagnostics.

Animals↗
PubMedDate not supplied

Inhibition of the growth of U-251 human glioblastoma in nude mice by polyamine deprivation.

An almost complete prevention of tumor growth was achieved in U-251 human glioblastoma xenografted nude mice, by partial decontamination of the gastrointestinal tract and feeding of a polyamine-free diet containing inhibitors of ornithine decarboxylase (DFMO) and of polyamine oxidase (MDL 72527). After one week of polyamine deprivation, spermidine concentrations were lowered, and spermine levels were increased in all tissues. In contrast, putrescine concentrations were only reduced in tumor and in brain. Erythrocyte polyamine determinations revealed differences similar to those observed in tissues: spermidine concentration was lowered by 50% and spermine level was 3-fold increased. If this or related treatments should become of therapeutic importance in the future, then the determination of erythrocyte polyamine levels might be of diagnostic value.

Animals↗
PubMedDate not supplied

In vivo antitumor activity of 4-amino 4-methyl 2-pentyne 1-al, an inhibitor of aldehyde dehydrogenase.

4-amino-4-methyl-2-pentyne-1-al (AMPAL), a new irreversible inhibitor of aldehyde dehydrogenase (ALDH) has been assayed for its in vitro and in vivo antitumor activity. In vitro, AMPAL inhibits the proliferation and the ALDH activity of L1210 and RBL5 cell lines. In vivo, AMPAL significantly increases the mean survival time of mice i.p. grafted with leukemia (L1210, P815, MBL2, EL4, RBL5 cell lines) or carcinoma cells (Krebs cell line), without haematopoetic toxicity. No carcinostatic effect was observed against the P388 leukemia and the 3LL Lewis lung carcinoma. A possible relationship between the ALDH isoenzyme activity of the tumor and its sensitivity to AMPAL is discussed in the light of previous reports concerning the role of aldehydes in cell growth control.

Aldehyde Dehydrogenase↗
PubMedDate not supplied

Clinical importance of erythrocyte polyamine level determination during bone marrow transplantation in children.

Previous studies have shown that red blood cell (RBC) spermidine (Spd) and spermine (Spm) concentrations appear to be a reliable index of cell proliferation. Our aim was to study the RBC polyamine level evolution (Spd and Spm) in bone marrow (BM) transplanted children. Because of our interest in the finding of an early blood criteria of BM regeneration, our study was based upon the chemotherapy - induced post-transplant aplasia period. After BM transplantation, two main periods were observed: the first (A-period) corresponded to abnormally low Spd levels. This period ended with an increasing amount of Spd reaching normal values and with an inversion in the Spd/Spm ratio which became greater than 1. The second (B) period was usually linked to abnormally high RBC Spd concentrations and a Spd/Spm ratio greater than 1. The end of the B-period was characterized by an increase in the granulocyte count (reaching 0.5 X 10(9) cells/l). Since the A- and B-periods are considered as a post-transplant aplasia period (only according to leukocyte count) and since normal RBC Spd levels occurred 14 days (SD = 4) after BM transplantation and 16 days (SD = 12) before granulocyte rise, these data led us to consider erythrocyte polyamine levels to be an earlier biological criteria of bone marrow engraftment than the number of circulating granulocytes.

Adolescent↗
PubMedDate not supplied

Spermidine uptake by erythrocytes from normal and Lewis lung carcinoma (3LL) grafted mice: I. In vitro study.

High red blood cell (RBC) spermidine levels have been observed in patients harboring various histological types of cancer. In an attempt to explain the mechanism of RBC spermidine uptake in the malignant cell growth process, erythrocytes from normal and (3LL) Lewis lung carcinoma grafted mice were incubated with [14C] spermidine in the presence of PBS or plasma from normal or 3LL grafted mice. Though RBC of cancer mice harbor abnormally elevated spermidine concentrations as compared with those of controls, when incubated with PBS, 3LL grafted mice exhibit [14C] spermidine uptake three times higher than that of normal mice erythrocytes in the same incubating conditions. Moreover, if plasma incubations always increase spermidine uptake in RBC from cancer mice compared with erythrocytes only incubated with PBS, plasma incubations are responsible for two opposite effects in RBC of normal mice: plasma increases spermidine uptake in PBS unwashed erythrocytes and lowers it in PBS washed RBC. One possible explanation for the observed plasma stimulating effect in RBC spermidine uptake might be the presence of a plasma component common to plasma from normal and cancer mice, able to interact with RBC membrane proteins. In erythrocytes from cancer mice, the high spermidine concentration would be responsible for the observed compactness in band 3 proteins involved in ionic transport through RBC stroma. In normal mice erythrocytes which exhibit low polyamine levels, the observed dissociation of band 3 proteins might explain the spermidine uptake in PBS washed normal RBC incubated with plasma. In vivo, this plasma component would participate in the stabilization of normal mice membrane proteins involved in RBC spermidine uptake.

Animals↗