Pathway toward catastrophe: cellular dynamics on hit-to-lead compound optimisation for current drug discovery pipelines

Abstract

Microtubules (MTs) are intracellular polymers that act as fundamental components of eukaryotic cells. Recent advances in protein purification techniques have begun to shed light on the importance of MTs intrinsic dynamic properties such as growth and shrinkage-both regulated by a cohort of molecular motors and microtubule-associated proteins. The dynamic instability of the MT cytoskeleton is crucial for cell division and motility, core processes that underpin abnormal behaviour in cancer development. Within this framework, for the past three years we have been carrying out in Brazil a PhD project entitled "Discovery of New Bioactive Ligands with Anticancer Properties" (FAPESP grant 2018/25.289-7), working on MT-targeting agents for the treatment of triple-negative breast and hormone-refractory prostate cancers-both of which are metastatic. From a set of seventy-nine initial compounds, seven passed the screening involving a series of in vitro assays: cell proliferation, migration, and invasion; experimental determination of pharmacokinetic parameters; tubulin polymerisation. The compounds' effect on tubulin polymerisation was found to be inhibitory, i.e., they promote destabilisation by favouring the switch from growing to shrinking ("catastrophes") at MT assembly. That said, here we describe a research proposal to image the outcome of the effects of those seven hit-compounds on MT dynamics, during a Research Internship Abroad programme under the supervision of Prof. Dr. Anna Akhmanova, at Utrecht University. For those samples, using time-lapse microscopy, kymographs will be generated to annotate and quantify MT dynamics. Prof. Akhmanova is one of the world's leading experts in the field of cytoskeleton cell biology and has played a key role in the development of microscopy in the Netherlands, where she is a Spinoza prize recipient (2018)-the highest Dutch scientific distinction. She regularly takes part in prestigious conferences and has published more than two hundred papers in leading journals, including Angewandte Chemie, Cancers, Cell, and Nature. In partnership with various companies, she has also studied how the cytoskeleton interacts with certain drugs. Moreover, Prof. Akhmanova is Deputy Editor of eLife, a life-sciences broad open access journal that aims to improve publishing practices in biomedical sciences. An elected member of the Royal Netherlands Academy of Arts and Sciences and the European Molecular Biology Organisation, she has received many important grants throughout her career, such as "Vidi" and "Vici" (The Netherlands Organisation for Scientific Research). At Prof. Akhmanova's laboratory, this conjunction of molecular biophysics techniques, cellular expertise, advanced microscopy, and multicolour image analysis will make possible to perform several experiments that are bound to be significant for our already screened compounds, in order to select those that will be forwarded for pre-clinical trials with animal models and to elect the lead ones. (AU)