Suivi thérapeutique des concentrations d'inhibiteurs de tyrosine kinase et d'autres médicaments oncologiques = Therapeutisches Drug-Monitoring der Konzentration von Tyrosinkinase-Inhibitoren und anderen Onkologika

Les médicaments anticancéreux sont souvent caractérisés par une importante variabilité pharmacocinétique interindividuelle, des relations entre concentration et réponse clinique et une marge thérapeutique étroite. Pourtant, le suivi thérapeutique des concentrations de ces médicaments (TDM) est encore rare en oncologie. Les bases scientifiques justifiant un TDM des nouvelles thérapies ciblées orales sont encore très hétérogènes. Cependant, d'assez solides évidences existent pour l'imatinib et certaines apparaissent progressivement pour d'autres composés. A côté de cela, le TDM est aussi pratiqué dans des situations spécifiques de traitement par certaines chimiothérapies conventionnelles. Des efforts considérables restent toutefois à réaliser pour mieux caractériser la pharmacocinétique de ces médicaments, pour préciser leurs relations concentration-effet et pour conduire des études prospectives randomisées évaluant le bénéfice clinique de l'approche TDM en oncologie.

Induction of calmodulin kinase IV by the thyroid hormone during the development of rat brain.

This communication reports the specific induction of calmodulin kinase IV by the thyroid hormone 3,3',5-triiodo-L-thyronine (T3) in a time- and concentration-dependent manner at a very early stage of brain differentiation using a fetal rat telencephalon primary cell culture system, which can grow and differentiate under chemically defined conditions. The induction of the enzyme that can be observed both on the mRNA and on the protein level is T3-specific, i.e. it cannot be induced by retinoic acid or reverse T3, and can be inhibited on both the transcriptional and the translational level by adding to the culture medium actinomycin D or cycloheximide, respectively. The earliest detection of calmodulin kinase IV in the fetal brain tissue of the rat is at days E16/E17, both on the mRNA as well as on the protein level. This is the first report in which a second messenger-dependent kinase involved in the control of cell regulatory processes is itself controlled by a primary messenger, the thyroid hormone.

c-Jun N-terminal kinase pathway inhibition in intracerebral hemorrhage.

Background: Inhibition of the c-Jun N-terminal kinase (JNK) pathway by the TAT-coupled peptide XG-102 (formerly D-JNKI1) induces strong neuroprotection in ischemic stroke in rodents. We investigated the effect of JNK inhibition in intracerebral hemorrhage (ICH). Methods: Three hours after induction of ICH by intrastriatal collagenase injection in mice, the animals received an intravenous injection of 100 mu g/kg of XG-102. The neurological outcome was assessed daily and the mice were sacrificed at 6 h, 1, 2 or 5 days after ICH. Results: XG-102 administration significantly improved the neurological outcome at 1 day (p < 0.01). The lesion volume was significantly decreased after 2 days (29 +/- 11 vs. 39 +/- 5 mm(3) in vehicle-treated animals, p < 0.05). There was also a decreased hemispheric swelling (14 +/- 13 vs. 26 +/- 9% in vehicle-treated animals, p < 0.05) correlating with increased aquaporin 4 expression. Conclusions: XG-102 attenuates cerebral edema in ICH and functional impairment at early time points. The beneficial effects observed with XG-102 in ICH, as well as in ischemic stroke, open the possibility to rapidly treat stroke patients before imaging, thereby saving precious time.

Cholinergic neurons of fetal rat telencephalon in aggregating cell culture respond to NGF as well as to protein kinase C-activating tumor promoters.

Serum-free aggregating cell cultures of fetal rat telencephalon treated with the potent tumor promoter phorbol 12-myristate 13-acetate (PMA) showed a dose-dependent, persistent stimulation of the enzymes choline acetyltransferase (ChAT), glutamic acid decarboxylase and glutamine synthetase. After elimination of the proliferating cells by treatment of the cultures with Ara-C (0.4 microM) only the cholinergic marker enzyme, ChAT, could be stimulated by tumor promoters. The non-promoting phorbol ester, 4 alpha-phorbol 12,13-didecanoate proved to be inactive in these cultures, whereas the potent non-phorbol tumor promoter, mezerein, produced an even greater stimulatory effect than PMA. Since PMA and mezerein are potent and specific activators of protein kinase C, the present results suggest a role for this second messenger in the development of cholinergic telencephalon neurons. Stimulation of ChAT required prolonged exposure (48 h) of the cultures to PMA and the responsiveness of the cholinergic neurons to the tumor promoters decreased with progressive cellular maturation. The cholinergic telencephalon neurons showed the same pattern of responsiveness for tumor promoters as for nerve growth factor (NGF). However, the combined treatment with NGF and either PMA or mezerein produced an additive stimulatory effect, suggesting somewhat different mechanisms of action.

MAP kinase pathways in UV-induced apoptosis of retinal pigment epithelium ARPE19 cells.

The retinal pigment epithelium (RPE) is constantly exposed to external injuries which lead to degeneration, dysfunction or loss of RPE cells. The balance between RPE cells death and proliferation may be responsible for several diseases of the underlying retina, including age-related macular degeneration (AMD) and proliferative vitreoretinopathy (PVR). Signaling pathways able to control cells proliferation or death usually involve the MAPK (mitogen-activated protein kinases) pathways, which modulate the activity of transcription factors by phosphorylation. UV exposure induces DNA breakdown and causes cellular damage through the production of reactive oxygen species (ROS) leading to programmed cell death. In this study, human retinal pigment epithelial cells ARPE19 were exposed to 100 J/m(2) of UV-C and MAPK pathways were studied. We first showed the expression of the three major MAPK pathways. Then we showed that activator protein-1 (AP-1) was activated through phosphorylation of cJun and cFos, induced by JNK and p38, respectively. Specific inhibitors of both kinases decreased their respective activities and phosphorylation of their nuclear targets (cJun and cFos) and reduced UV-induced cell death. The use of specific kinases inhibitors may provide excellent tools to prevent RPE apoptosis specifically in RPE diseases involving ROS and other stress-related compounds such as in AMD.

Polar gradients of the DYRK-family kinase Pom1 couple cell length with the cell cycle.

Cells normally grow to a certain size before they enter mitosis and divide. Entry into mitosis depends on the activity of Cdk1, which is inhibited by the Wee1 kinase and activated by the Cdc25 phosphatase. However, how cells sense their size for mitotic commitment remains unknown. Here we show that an intracellular gradient of the dual-specificity tyrosine-phosphorylation regulated kinase (DYRK) Pom1, which emanates from the ends of rod-shaped Schizosaccharomyces pombe cells, serves to measure cell length and control mitotic entry. Pom1 provides positional information both for polarized growth and to inhibit cell division at cell ends. We discovered that Pom1 is also a dose-dependent G2-M inhibitor. Genetic analyses indicate that Pom1 negatively regulates Cdr1 and Cdr2, two previously described Wee1 inhibitors of the SAD kinase family. This inhibition may be direct, because in vivo and in vitro evidence suggest that Pom1 phosphorylates Cdr2. Whereas Cdr1 and Cdr2 localize to a medial cortical region, Pom1 forms concentration gradients from cell tips that overlap with Cdr1 and Cdr2 in short cells, but not in long cells. Disturbing these Pom1 gradients leads to Cdr2 phosphorylation and imposes a G2 delay. In short cells, Pom1 prevents precocious M-phase entry, suggesting that the higher medial Pom1 levels inhibit Cdr2 and promote a G2 delay. Thus, gradients of Pom1 from cell ends provide a measure of cell length to regulate M-phase entry.

CMO Annual Report 2010 (PDF 4.43 MB)

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