Polyphenols purified from the Brazilian aroeira plant (Schinus terebinthifolius, Raddi) induce apoptotic and autophagic cell death of DU145 cells.

Polyphenols extracted from many plants have shown antiproliferative and antitumor activities in a wide range of carcinogenesis models. The antiproliferative effects of polyphenols purified from the Brazilian aroeira plant (Schinus terebinthifolius, Raddi) were investigated on the androgen-insensitive DU145 human prostatic carcinoma cell line. A F3 fraction purified from leaf extract inhibited the DU145 cell proliferation more than 30-fold compared to the crude extract. By flow cytometric analysis, the polyphenol fraction was demonstrated to induce G0/G1 cell growth arrest and cell apoptosis. This apoptosis was evidenced by caspase 3 stimulation in F3-treated cells as compared to crude extract treated cells. The acid phosphatase activity of lysosomes was strongly activated in the lysosomal fraction of the F3-treated DU145 cells. This lysosomal activation, together with the appearance of autophagic vacuoles, suggests that "type 2 physiological cell death" was also involved in this antiproliferative effect. HPLC analysis of this F3 fraction showed 18 different subfractions. Among these subfractions, F3-3, F3-7 and F3-13 strongly inhibited DU145 cell proliferation in a dose-dependent manner. However, the nature of these polyphenols remains unknown since only one (Isoquercitrin) of the tested pure polyphenols co-migrated with F3-13. Since lysosomotropic drugs are considered as possible regulators of lysosome activity, aroeira polyphenols could target lysosomes of prostatic cancer cells to induce autophagic cell death.

French multicentric evaluation of mdr1 gene expression by RT-PCR in leukemia and solid tumours. Standardization of RT-PCR and preliminary comparisons between RT-PCR and immunohistochemistry in solid tumours. French Network of the Drug Resistance Intergroup, and Drug Resistance Network of Assistance Publique-Hôpitaux de Paris.

Since there is no consensus on the techniques for multidrug resistance (MDR) phenotype evaluation, many discrepancies concerning the importance and frequency of mdr1 gene expression in leukemias and solid tumors are observed in the literature. In order to establish an inter-laboratory consensus in France, a multicenter study was carried out to propose further guidelines for MDR phenotype evaluation. The techniques used by the 38 laboratories participating in the trial were: immunodetection (immunohisto and/or cytochemistry, flow cytometry), functional tests, reverse transcription-polymerase chain reaction (RT-PCR) or Northern blot. We present the results obtained by 19 laboratories concerning the measurement of mdr1 gene expression assessed by RT-PCR or Northern blot in: (1)19 samples of tumor cells obtained from leukemic patients; (2) six solid tumor samples obtained at surgery; (3) eight cell lines exhibiting variable levels of resistance, and; (4)10 preparations of RNA and of cDNA obtained from solid tumors. Standardization of the RT-PCR technique and preliminary results comparing RT-PCR with immunohistochemistry in solid tumors are also reported.

Technetium-99m-sestamibi uptake by human benign and malignant breast tumor cells: correlation with mdr gene expression.

UNLABELLED: Early diagnosis of multidrug-resistance (MDR) development is extremely important for the judicious choice of treatment protocols in breast cancer chemotherapy. In this study, the mechanism of 99mTc-sestamibi uptake by nine human breast tumor cell lines was analyzed as a function of P-glycoprotein (PgP) expression. METHODS: Technetium-99m-sestamibi radioactivity incorporation into the cells was determined after different times of incubation at 37 degrees C. We analyzed the mechanism of 99mTc-sestamibi uptake as follows: (a) effect of temperature (4 degrees C); (b) influence of extracellular 99mTc-sestamibi concentration; and (c) competitive inhibition of cell uptake with cold 99mTc-sestamibi. Technetium-99m-sestamibi uptake was compared to the level of PgP determined by Western blotting. The PgP reversing effect of verapamil was evaluated at different drug concentrations (50, 200, 500 microM). RESULTS: Technetium-99m-sestamibi uptake plateaued at 60 min, which was 14 times lower at 4 degrees C than at 37 degrees C and was directly proportional to the extracellular concentration between 0.3 and 10 nM. Technetium-99m-sestamibi percentage uptake by cells expressing nonimmunodetectable levels of PgP was significantly higher (7.3% +/- 0.6% (s.d.) to 14.9% +/- 1.9%) than that by cells expressing high PgP levels (0.7% +/- 0.4%, p < 0.001). In the presence of verapamil, a known reverser of PgP functions, 99mTc-sestamibi uptake was increased by a factor of 2 in cells expressing no detectable levels of PgP and by a factor of 12 in cells with high PgP levels. CONCLUSION: Technetium-99m-sestamibi uptake by these breast tumor cells is energy-dependent but not specific. These data suggest that 99mTc-sestamibi imaging may be used as a noninvasive technique to diagnose the presence of MDR in breast tumors in vivo.

Involvement of glutathione in loss of technetium-99m-MIBI accumulation related to membrane MDR protein expression in tumor cells.

UNLABELLED: It was reported recently that 99mTc-hexakis-2-methoxyisobutyl isonitrile (MIBI) uptake is drastically reduced in cancer cells that express the multidrug resistance (MDR) product, Pgp 170 kDa (Pgp), suggesting that 99mTc-MIBI is a transport substrate for this transmembrane glycoprotein. In our study, we explored if another pump, a multidrug resistance-associated protein (MRP), could affect 99mTc-MIBI uptake. In addition, we studied the involvement of intracellular glutathione (GSH) as a modulator of 99mTc-MIBI uptake by both Pgp and MRP proteins. METHODS: MDR1 and MRP gene expression in seven human tumor cell lines was determined on a transcriptional level by reverse transcriptase polymerase chain reaction and on a protein level using immunocytochemistry. Technetium-99m-MIBI uptake was quantified by measuring radioactivity retained in the cells incubated at 37 degrees C in the presence or absence of buthionine sulfoximine (BSO), which depletes cellular GSH. The cellular GSH content was determined with Ellman's reagent. RESULTS: Cell lines were classified according to their phenotypic characteristics: 1/MRP-/Pgp-: breast cancer cells (MCF7), lung carcinoma cells (H69S) and mouth epidermoid tumor cells (KB 3.1), 2/MRP-/Pgp+: MCF7 mdr+, KBA.1; and 3/MRP+/Pgp-: small-cell lung carcinoma (H69 AR and A 549). Technetium-99m-MIBI uptake was significantly lower in cells expressing MRP as well as Pgp compared to MRP/Pgp cells. Depletion of GSH by BSO resulted in an increase of 99mTc-MIBI uptake in multidrug resistant cells overexpressing MRP but not expressing Pgp. CONCLUSION: Technetium-99m-MIBI is extruded by both Pgp and MRP efflux pumps. However, MRP action is indirect and involves intracellular GSH for a presumed interaction with the 99mTc-MIBI before its effLux. Technetium-99m-MIBI seems to be a good candidate for a noninvasive marker to diagnose MDR1 related to Pgp and MRP expression in tumors of different origin.

In vivo effects of noradrenaline and noradrenergic receptor agonists and antagonists on rat cerebellar cyclic GMP levels.

Cerebellar cyclic GMP levels can be altered by neurotransmitters and their receptor agonists and antagonists. In this study, we investigated the action of noradrenaline and certain drugs affecting alpha- and beta-adrenoceptors on rat cerebellaceptor agonists such as methoxamine and phenylephrine increased cGMP levels. alpha-Adrenoceptor antagonists such as phentolamine, phenoxybenzamine and ARC 239 decreased cGMP levels, whereas yohimbine and piperoxane which are known to act as presynaptic alpha-adrenoceptor antagonists had no effect. The action of clonidine which decreased cGMP levels at low doses was probably due to the fact that this adrenoceptor agonist inhibited the release of noradrenaline from adrenergic nerve terminals, since piperoxane injected prior to clonidine antagonized the effect of clonidine on cerebellar cGMP, and since pretreatment of the animals with 6-hydroxydopamine partially antagonized the effect of clonidine. Isoproterenol, a beta-noradrenergic agonist had no effect on cerebellar cGMP levels. Propranolol, a beta-noradrenergic antagonist decreased cGMP levels. Phenoxybenzamine or propranolol injected prior to noradrenaline decreased cerebellar cGMP.

Effect of L-glutamate and kainate on rat cerebellar cGMP levels in vivo.

L-glutamate and kainate administered intracerebroventricularly (i.c.v.) both produced dose-dependent increases in rat cerebellar cGMP. The increased cGMP produced by L-glutamate, but not that produced by kainate, could be completely abolished by the glutamate antagonist glutamate diethylester which had no effect alone. The data suggest that L-glutamate and kainate may be acting upon different sub-populations of glutamate receptors, both of which may be involved in the regulation of cerebellar cGMP levels.

Effects of L-glutamic acid and kainic acid on central cardiovascular control.

L-Glutamic acid and kainic acid injected into the cisterna magna of dogs, produced a dose-dependent increase in blood pressure and a decrease in heart rate. In contrast, intravenous injection of both compounds was ineffective. The hypertension was probably due to an increase in sympathetic tone as guanethidine prevented the rise in blood pressure induced by central administration of L-glutamic acid and kainic acid. Kainic acid was 1 000 fold more potent than L-glutamic acid.

Anticonvulsant activity of muscimol and gamma-aminobutyric acid against pyridoxal phosphate-induced epileptic seizures.

The intracerebroventricular injection of pyridoxal phosphate (PLP, 0.125-1.25 mumol/rat) causes epileptic seizures (4 min leads to 1 min) that are preventable or reversible by GABA (1 mumol/rat), by muscimol (0.025 mumol/rat), or by diazepam (1.75 mumol/rat). At the peak of PLP-induced convulsions, the activities of GAD and GABA-T in 14 regions of rat brain remained unaltered, whereas the concentrations of PLP remained elevated. The PLP-induced convulsion was blocked by DABA (10 mumol/rat) but was not altered by beta-alanine (50 mumol/rat). The previous in vitro studies have shown that PLP increases the uptake of [3H]GABA into synaptosomes and inhibits the binding of [3H]GABA to synaptic membranes. These data suggest that PLP-induced convulsion is due to reduced availability of GABA to its recognition sites, rather than to alteration in the activity of GABA metabolizing enzymes, or unavailability of PLP as a coenzyme for GAD and GABA-T. Since the duration of PLP-induced epileptic seizures is short and can be prevented by GABA agonists, PLP may be used as a tool to study the nature of GABA-mediated neuroinhibition and the properties of GABA receptor sites.

Multiple binding sites of [3H]clonidine on hepatic plasma membranes.

The binding of [3H]clonidine on mouse liver plasma membrane was a rapid, saturable and reversible process. It was characterized by two types of population: high affinity receptors with KD of 6.76 +/- 1.02 nM and Bmax of 106.15 +/- 24.05 fmol/mg protein, and low affinity receptors with KD of 63.66 +/- 12.85 nM and Bmax of 818.06 +/- 128.49 fmol/mg protein. Displacement of [3H]clonidine from its binding sites by various ligands indicated that alpha 1--as well as alpha 2--adrenoceptors were involved in the high affinity system. The respective participation of these two types of receptors was discussed.

Primary breast cancer imaging with technetium-99m sestamibi and its relation with P-glycoprotein overexpression.

The aim of this preliminary study was to evaluate retrospectively sestamibi scintigraphy in relation to the presence of the 170-kDa P-glycoprotein (Pgp), which represents an expression of multidrug resistance in patients with primary breast cancer. Fifteen women (age range 37-76 years) were referred for technetium-99m sestamibi scintigraphy because of suspicious breast lesions detected by mammography and ultrasonography, and subsequently assessed by fine-needle aspiration. Scintigraphy was performed 30 min following the injection of 500 MBq 99mTc-sestamibi. Three planar anterior and oblique images were obtained with the patient in the supine position. Excised tumours were assessed for cytosolic CA 15.3, oestrogen (OR) and progesterone (PR) receptors and c-erb B2 neu oncogene. Pathology revealed that only 13 of the 15 patients had malignant tumours. The two benign tumours were sestamibi-negative and Pgp-positive. Sestamibi scintigraphy was positive in 10 of the 13 malignant lesions (including nine of ten infiltrating ductal carcinomas). Two of the three lesions with false-negative scintigraphy were Pgp-negative; in one of these cases histology revealed an invasive lobular carcinoma and in the other, mucinous adenocarcinoma. The third false-negative lesion was a Pgp-positive infiltrating ductal carcinoma which was c-erb B2 neu-negative but CA 15.3-, OR- and PR-positive. This preliminary study confirms that the resistance to chemotherapy which may occur in patients with primary breast cancer can be a cause of negative sestamibi scintigraphy.

[Lysosome-rich synaptosomal preparations from rat mesencephalus (author's transl)]. / Richesse en lysosomes des préparations de synaptosomes du mésencéphale de rat

Subcellular fraction, enriched with synaptosomes, obtained from rat brain has been found contaminated by lysosomes, as evidenced by the high content of acid phosphatase, their biochemical marker.

[In vitro effect of serotonin on the enzyme activities of glutamate decarbosylase and GABA transaminase at the level of acellular preparations of rat mesencephalon synaptosomes]. / Effet, in vitro, de la sérotonine sur les activités enzymatiques de la glutamate décarboxylase et de la GABA-transaminase du nuveau de préparations acellulaires

The effect of serotonin on glutamate decarboxylase and GABA-transaminase was studied, in vitro, in synaptosome homogenates from rat mesencephalon. Serotonin dissolved in the incubation medium inhibits glutamate decarboxylase activity and stimulates GABA-transaminase activity.