Thesis presented June 24, 2008

Abstract:
Microtubules are long, hollow, cylindrical protein polymers composed of tubulin subunits. They are highly dynamic polymers involved in a wide variety of cellular processes including the formation of the mitotic spindle. Defects in microtubule function can have severe consequences on cell viability, leading to a disruption of cell division and, consequently, to an induction of cell death. Therefore, the search for new agents that disrupt the tubulin/microtubule system is still an important challenge in anticancer therapy. Usually, such agents were discovered either via inhibition of cancer cell cultures or by direct screening for the inhibition of tubulin assembly in vitro. We designed an automated multi-parametric cell-based assay that allows the selection of agents which modify microtubule dynamic. The rationale of this assay is based on the unique substrate properties of the tubulin modifying enzymes involved in the tubulin tyrosination cycle. Following several screening campaigns, we have discovered a set of compounds from three structurally unrelated classes, acting on these dynamics and showing antiproliferative activity towards various cancer cell lines. Then, we demonstrated that one compound was able to slow down the microtubule dynamics and induce abnormal mitosis with a mechanism of action different from those of other microtubule-stabilizers like taxol®. We have also identified two classes of microtubule polymerization inhibitors. The first class acts by direct interaction within the tubulin whereas the second class probably interacts with microtubule effectors.

Keywords:
Microtubules, microtubule dynamics, detyrosinated tubulin, cancer, chemogenomics​, High Throughtput Screening, phenotypic test