[Study impacto: Descriptive analyzis of pharmacist's clinical practice in onco-hematology]. / Étude impacto : analyse descriptive des pratiques de pharmacie clinique en cancérologie.

Pharmaceutical analyses of chemotherapy prescriptions by hospital pharmacists are activities codified by regulation and rules (bon usage). The involvement of the pharmacists in clinical pharmacy activities in the oncology setting is not clearly identified, justifying the development of a mapping of these activities from a questionnaire addressed to the professionals. One hundred and seven centers have participated to this study at the national level (overall participation rate of 32.4%). More than 95% of them used a computerized ordering system and three quarter of them submit the introduction of new compounds to an analysis by the drug therapeutic committee. Prescription analysis allowed detecting around 2% of errors from the current prescription. Clinical pharmacist participates to tumor boards of onco-hematology (RCP) at a level of 46% for senior pharmacist and 42% for junior pharmacist. This involvement in the RCP allowed anticipating protocol's modification and temporary used authorization. Ninety-two percent of the senior pharmacists estimate that they highlight the risk of no reimbursement for prescription out of the guideline during RCP, resulting to a modification of the prescription for 40% of them. This level of intervention is lower with respectively 64% and 10% for the juniors. This study underlines the expert value of the clinical pharmacist dedicated to oncology setting in pre and post analysis prescriptions. It could be targeted by a prospective analysis of both clinical and pharmacoeconomics impact of these interventions.

Microtubule-targeted agents: when mitochondria become essential to chemotherapy.

Microtubule-Targeting Agents (MTAs) constitute a class of drugs largely used for cancer treatment in adults and children. In cancer cells, they suppress microtubule dynamics, and induce cell death via the mitochondrial intrinsic pathway. To date, links between mitochondria and microtubule network disturbance in MTAs mechanism of action are not obvious. The aim of the present contribution is to provide elements that could answer to the question: how far are mitochondria essential to anticancer chemotherapy that targets the microtubule cytoskeleton? We review the main molecular candidates to link microtubule alteration with the apoptotic mitochondrial pathway control. Involvement of direct targeting of mitochondria in MTA efficacy is also discussed. Furthermore, we line up current evidence and emerging concepts on the participation of both mitochondria and microtubule in MTA neurotoxic side effects. To decipher the interconnections between the mitochondrial and the microtubule networks may help to improve cancer cell response to chemotherapy.

Microtubule targeting agents: from biophysics to proteomics.

This review explores various aspects of the interaction between microtubule targeting agents and tubulin, including binding site, affinity, and drug resistance. Starting with the basics of tubulin polymerization and microtubule targeting agent binding, we then highlight how the three-dimensional structures of drug-tubulin complexes obtained on stabilized tubulin are seeded by precise biological and biophysical data. New avenues opened by thermodynamics analysis, high throughput screening, and proteomics for the molecular pharmacology of these drugs are presented. The amount of data generated by biophysical, proteomic and cellular techniques shed more light onto the microtubule-tubulin equilibrium and tubulin-drug interaction. Combining these approaches provides new insight into the mechanism of action of known microtubule interacting agents and rapid in-depth characterization of next generation molecules targeting the interaction between microtubules and associated modulators of their dynamics. This will facilitate the design of improved and/or alternative chemotherapies targeting the microtubule cytoskeleton.

Patupilone-induced apoptosis is mediated by mitochondrial reactive oxygen species through Bim relocalization to mitochondria.

Among the new microtubule-targeted agents, the epothilone family of molecules has shown promising anticancer potential, and clinical trials are currently underway for patupilone (epothilone B) in various cancer indications. In this study, we characterized novel aspects of patupilone's cellular action that may underlie its potent cytotoxicity in human neuroblastoma cells. Patupilone induced mitochondrial membrane potential collapse, mitochondrial morphological changes, and cytochrome c release, leading to apoptosis. Within the first 2 h, patupilone increased the generation of reactive oxygen species (ROS; i.e., superoxides and hydrogen peroxide, 33+/-6 and 51+/-3% increase, respectively), specifically from mitochondria. ROS scavengers and mitochondrial DNA depletion [rho(-) cells] significantly protected cells against patupilone cytotoxicity, indicating that ROS generation is a key event in the initial phase of apoptosis. Although the Bim expression level was not modified by patupilone, this proapoptotic protein accumulated in the mitochondrial compartment (2.4-fold increase at IC70) after only a 6-h treatment. In contrast, Bax and Bcl-2 mitochondrial levels were not changed during treatment. It is noteworthy that ROS inhibition prevented Bim relocalization to mitochondria and mitochondrial membrane changes induced by patupilone. Altogether, our data reveal that patupilone-mediated ROS production by mitochondria initiates the intrinsic signaling cascade by inducing Bim accumulation in mitochondria. These results might explain the superior activity of patupilone in tumor cells compared with paclitaxel that is, until now, the clinical reference among microtubule-stabilizing agents. Furthermore, our data highlight the importance of mitochondria that simultaneously assume the role of activator and integrator of apoptotic signals triggered by patupilone.

Paclitaxel induces release of cytochrome c from mitochondria isolated from human neuroblastoma cells'.

Paclitaxel is an antimicrotubule agent that induces mitotic block and apoptosis. We show for the first time that paclitaxel acts directly or mitochondria isolated from human cancer cells. In isolated yeast mito chondria, paclitaxel (15 microM) induced an 18% increase in the respiration rate, with no concomitant release of cytochrome c. In isolated neuroblas toma mitochondria, paclitaxel (10-100 microM) induced a 27-72% release o cytochrome c. Release was prevented by cyclosporin A, suggesting the involvement of the permeability transition pore. Doxorubicin did no induce cytochrome c release, whereas vinorelbine, another antimicrotu bule agent, did. Thus, antimicrotubule agents can directly affect mito chondria to induce apoptosis.

Safety and efficacy of temozolomide in patients with recurrent anaplastic oligodendrogliomas after standard radiotherapy and chemotherapy.

PURPOSE: Most primary oligodendrogliomas and mixed gliomas (oligoastrocytoma) respond to treatment with procarbazine, lomustine, and vincristine (PCV), with response rates of approximately 80%. However, limited data on second-line treatments are available in patients with recurrent tumors. A novel second-generation alkylating agent, temozolomide, has recently demonstrated efficacy and safety in patients with recurrent glioblastoma multiforme and anaplastic astrocytoma. This study describes the effects of temozolomide in patients with recurrent anaplastic oligodendroglioma (AO) and anaplastic mixed oligoastrocytoma (AOA). PATIENTS AND METHODS: Forty-eight patients with histologically confirmed AO or AOA who had received previous PCV chemotherapy were treated with temozolomide (150 to 200 mg/m2/d for 5 days per 28-day cycle). The primary end point was objective response. Secondary end points included progression-free survival (PFS), time to progression, overall survival (OS), safety, and tolerability. RESULTS: Eight patients (16.7%) experienced a complete response, 13 patients (27.1%) experienced a partial response (objective response rate, 43.8%), and 19 patients (39.6%) experienced stable disease. For the entire treatment group, median PFS was 6.7 months and median OS was 10 months. For objective responders, median PFS was 13.1 months and median OS was 16 months. For complete responders, PFS was more than 11. 8 months and OS was more than 26 months. Response correlated with improved survival. Temozolomide was safe and well tolerated. Twelve patients developed grade 1/2 thrombocytopenia and three patients developed grade 3/4 thrombocytopenia. CONCLUSION: Temozolomide is safe and effective in the treatment of recurrent AO and AOA.

Opposite effects of antimicrotubule agents on c-myc oncogene expression depending on the cell lines used.

We investigated the expression of c-myc in HT29-D4, HBL100 and Caco-2 cells treated with microtubule stabilising (paclitaxel) or depolymerising agents (vinblastine, nocodazole). After induction by epidermal growth factor (EGF), c-myc expression decreased in HT29-D4 cells treated with all the antimicrotubule agents. In HBL100 and Caco-2, when microtubules were stabilised with paclitaxel, c-myc expression also decreased. In contrast, its expression increased after treatment with depolymerising agents. In both cell lines, we also observed that depolymerising agents alone induced c-myc expression whilst paclitaxel had no effect. This mRNA induction was confirmed at the protein level. In HT29-D4, no variation of c-myc expression was observed. Then, we showed that the increase of mRNA level was due to activation of gene transcription. These results indicate that modulation of c-myc expression varied depending on the cell lines used and the type of antimicrotubule agents. This work provides a potential link between the microtubular network and c-myc gene expression.

Qualitative study of the interaction mechanism of estrogenic drugs with tubulin.

Synthetic estrogenic drugs (E-diethylstilbestrol, erythro-hexestrol and E,E-dienestrol) inhibit tubulin assembly and erythro-hexestrol and E,E-dienestrol lead to the formation of twisted ribbon structures. For the inhibitory effect on tubulin assembly, estrogenic drugs seem to interact directly with tubulin 6S on site(s) analogous to the colchicine-site, but independent of the GTP- and vinblastine-sites. This binding does not involve tubulin tryptophanyl residues or sulfhydryl groups. The influence of temperature, calcium and magnesium on the formation of twisted ribbon structures induced by the binding of estrogenic drugs to microtubular protein and tubulin has also been studied. This formation is strongly magnesium-dependent whereas preformed twisted ribbon structures are calcium- and chilling-insensitive.

Caspase-8 activation independent of CD95/CD95-L interaction during paclitaxel-induced apoptosis in human colon cancer cells (HT29-D4).

Antimicrotubule agent-induced apoptosis was examined in the proliferating human colon cancer cell line HT29-D4. G2/M arrest and subsequent apoptosis were dose-dependent, both observed with 100 nM paclitaxel or docetaxel and 10 nM vinorelbine. Bcl-x(L) phosphorylation was observed simultaneously with mitotic block, then caspase-3 cleavage and poly(ADP-ribose) polymerase degradation were detected 48 hr later. By using both enzymatic assay and immunoblot detection of cleaved fragments, we showed that caspase-8, a central component of the CD95-induced apoptotic pathway, was significantly activated during paclitaxel exposure, contemporary to apoptosis occurrence. Caspase-8 activation and apoptosis were independent of CD95 ligation and evidenced only for concentrations inducing Bcl-x(L) phosphorylation and a decrease in mitochondria permeability. Similar results were obtained with docetaxel and vinca alkaloids. Thus, antimitotic drugs may induce apoptosis via caspase-8 activation independently of CD95/CD95-L. Caspase-8 may be a common mediator of anticancer drug-induced apoptosis that could represent a promising target for future therapies.

The in vitro effect of some nitroimidazoles on microtubule formation.

The in vitro effects of some nitroimidazoles (metronidazole, ornidazole) and their metabolites on microtubule formation have been tested. Cyclic metabolites are without effect. Metabolites proceeding from cleavage of the imidazole ring inhibit microtubule formation and reduce the polymerization rate of tubulin. This inhibitory effect might be correlated to some of the side-effects of these drugs. Isaxonine phosphate corrects this effect.

Comparative effects of taxol and Taxotere on two different human carcinoma cell lines.

The effects of taxoids (taxol and Taxotere) were followed on two human cancerous cell lines (bladder carcinoma J82 cells and epidermoid carcinoma KB 3-1 cells). Three cellular parameters were studied, viz., the qualitative effect on cellular microtubules, the quantitation of tubulin, and the antimitotic action, using two-parametric flow-cytometric analyses in treated cells. In both of the cell lines the tubulin content increased after taxoid treatment before the accumulation of cells in the G2/M phase. The effects of taxoids on tubulin appeared at about a 10-fold lower concentration on KB cells than on J82 cells. After drug exposure, the microtubule network showed a striking difference between the two cell lines: microtubule bundles were predominant in the J82 cell line, whereas multiple asters were prevalent in the KB cell line. The formation of these structures was dose- and time-dependent. Asters were observed in mitotic cells and bundles were seen in interphase cells. The reversibility of these structures in both cell lines varied with the duration of exposure to drug. Some differences were shown between taxol and Taxotere: the effects of Taxotere as compared with taxol appeared at a 2-fold lower concentration and their reversibility was slower.

Ribavirin-induced resistance to heat shock, inhibition of the Ras-Raf-1 pathway and arrest in G(1).

Ribavirin [1-(beta-D-ribofuranosyl)1,2,4-triazole-3-carboxamide (virazole)], a specific inhibitor of inositide 5'-monophosphate dehydrogenase (IMPDH), induces a strong depletion of GTP pools in IGR39 cells. After a 3-day treatment, the cell cycle was reversibly arrested in G(0)/G(1), suggesting the involvement of GTP in the cell cycle process. The reduction of the GTP cell content modified the appearance of the microtubule network, as examined using immunofluorescence. However, the dynamics of repolymerisation were not altered. When arrested in G(0)/G(1), cells displayed a surprising resistance to a 3-h period of heat shock at 45 degrees C. Considering the lack of coimmunoprecipitation of p21ras with Raf-1, the reduction of the level of GTP-associated p21ras and the decrease of the activation of the extracellular signal-regulated protein kinases (ERK), also known as mitogen-activated protein (MAP) kinase, in ribavirin-treated cells, we suggest a possible relationship between the expression of heat-shock proteins and the change, in GTP-depleted cells, of the regulation of Raf kinase by ras protein.

Intraerythrocytic water relaxation rates in amyotrophic lateral sclerosis. An NMR investigation.

Water relaxation rates 1/T2 in erythrocytes from amyotrophic lateral sclerosis (ALS) patients were studied by NMR. The spin-spin relaxation time of water protons in erythrocyte suspension was measured in the presence of a paramagnetic reagent which did not enter the cell. Our results show that red blood cell membranes exhibit a diminished water permeability in some ALS patients. Moreover, the activation energy value of water is lower in ALS patients than in healthy controls.

A controlled one-year trial of dextromethorphan in amyotrophic lateral sclerosis.

In a one-year parallel group double-blind placebo-controlled study of dextromethorphan (1.5 mg/kg) in amyotrophic lateral sclerosis, no significant differences were observed in the rate of progression (Norris scale) in comparing 24 patients randomly assigned to the dextromethorphan group and 25 patients randomly assigned to the placebo group. Of the 24 patients in the dextromethorphan group, 17 had limb onset and 7 had bulbar onset disease; average duration of disease was 12.5 +/- 6 months and sex ratio (M:F) was 1.4:1. Of the 25 patients in the placebo group, 18 had limb onset and 7 had bulbar onset disease; average duration of disease was 9.9 +/- 6 months and sex ratio (M:F) was 1.55:1. Dextromethorphan is a weak noncompetitive N-methyl-D-aspartate (NMDA) antagonist and higher doses or other potent NMDA receptor antagonists should be tested.

Inhibition of microtubule formation by uremic toxins: action mechanism and hypothesis about the active component.

We show in vitro inhibitory effect of a mixture of uremic toxins on tubulin 6S polymerization. It proves the existence of a direct interaction protein-toxin where micro-tubule associated proteins are not involved. A similar phenomenom could occur in uremic neuropathy. The action mechanism of this interaction is quite different from that of classical tubulin inhibitors: Vinca alcaloïdes and colchicine. Finally we hypothesize about the active molecule.

Inhibition in vitro of the polymerization of tubulin by uremic middle molecules: corrective effect of isaxonine.

The polymerization of tubulin leads to the formation of microtubules which are one of the components of the axons of nerve cells. This reaction is the limiting factor in the growth of axons. Uremic middle molecules inhibit in vitro the polymerization of tubulin in a dose dependent way. It is possible that a similar phenomenon could occur in vivo in uremic patients, and this might be involved in the development of neuropathy. In addition, isaxonine phosphate counteracts the inhibitory effect of uremic middle molecules on the polymerization of tubulin.

[Modification of the response to paclitaxel of human differentiated colon cancer line after long-term treatment at very low dose]. / Modification de la réponse au paclitaxel d'une lignée cancéreuse humaine de côlon différenciée après traitement continu à très faible dose.

Taxoids (paclitaxel, Taxol and docetaxel, Taxotere), drugs which stabilize microtubules, demonstrate marked activity against ovarian, brain and lung cancer. We investigated, on the human colon adenocarcinoma HT29-D4 cell line, firstly the effects of taxoids in function of the differentiation state and secondly the effects of a low dose of paclitaxel on the differentiation process. The cellular parameters studied were microtubular network, cell cycle and cell tubulin content. Undifferentiated cells treated with paclitaxel or docetaxel (10-100 nM) classically induced bundles in interphasic cells and pseudoasters in mitotic cells, arrest in cell cycle in G2M and increase in tubulin content. Inversely, no modification was observed in differentiated cells after similar taxoid treatment. Long-term low-dose pretreatment of differentiated cells restitutes some sensitivity to taxoids since these cells become responsive to further taxoid treatment, as reflected by modifications of the microtubule network.

Ascorbic acid derivatives in two different fractions of uremic toxins.

The middle-molecular-weight uremic toxins which accumulate in uremic plasma seem to be associated with various uremic disorders such as uremic neuropathy and defects in the sodium pump. By a multi-step chromatographic method, two fractions of these toxins were isolated and studied because one inhibits microtubule formation in vitro (fraction 2-5), and the other impairs the sodium pump in living erythrocytes (fraction 2-3). An additional chromatographic method allows the separation of these fractions and isolation of two components: fractions 2-3-V and 2-5-III. Analyses by UV and 1H NMR spectrometry identified these compounds as two different ascorbic acid derivatives. 2-3-V is not yet totally identified and 2-5-III corresponds to ascorbic acid 2-sulfate. These two metabolites exert no toxic effects but they have the same chromatographic behavior as uremic toxins.