PM534, an Optimized Target-Protein Interaction Strategy through the Colchicine Site of Tubulin.

Targeting microtubules is the most effective wide-spectrum pharmacological strategy in antitumoral chemotherapy, and current research focuses on reducing main drawbacks: neurotoxicity and resistance. PM534 is a novel synthetic compound derived from the Structure-Activity-Relationship study on the natural molecule PM742, isolated from the sponge of the , family , genus (du Bocage 1869). PM534 targets the entire colchicine binding domain of tubulin, covering four of the five centers of the pharmacophore model.

Chemical modulation of microtubule structure through the laulimalide/peloruside site.

Taxanes are microtubule-stabilizing agents used in the treatment of many solid tumors, but they often involve side effects affecting the peripheral nervous system. It has been proposed that this could be related to structural modifications on the filament upon drug binding. Alternatively, laulimalide and peloruside bind to a different site also inducing stabilization, but they have not been exploited in clinics.

Effect of Clinically Used Microtubule Targeting Drugs on Viral Infection and Transport Function.

Microtubule targeting agents (MTAs) have been exploited mainly as anti-cancer drugs because of their impact on cellular division and angiogenesis. Additionally, microtubules (MTs) are key structures for intracellular transport, which is frequently hijacked during viral infection. We have analyzed the antiviral activity of clinically used MTAs in the infection of DNA and RNA viruses, including SARS-CoV-2, to find that MT destabilizer agents show a higher impact than stabilizers in the viral infections tested, and FDA-approved anti-helminthic benzimidazoles were among the most active compounds.

Crystal Structure of the Cyclostreptin-Tubulin Adduct: Implications for Tubulin Activation by Taxane-Site Ligands.

It has been proposed that one of the mechanisms of taxane-site ligand-mediated tubulin activation is modulation of the structure of a switch element (the M-loop) from a disordered form in dimeric tubulin to a folded helical structure in microtubules. Here, we used covalent taxane-site ligands, including cyclostreptin, to gain further insight into this mechanism. The crystal structure of cyclostreptin-bound tubulin reveals covalent binding to βHis229, but no stabilization of the M-loop.

Analyzing Mitotic Chromosome Structural Defects After Topoisomerase II Inhibition or Mutation.

For analyzing chromosome structural defects that result from topoisomerase II (topo II) dysfunction we have adapted classical cell cycle experiments, classical cytological techniques and the use of a potent topo II inhibitor (ICRF-193). In this chapter, we describe in detail the protocols used and we discuss the rational for our choice and for the adaptations applied. We clarify in which cell cycle stages each of the different chromosomal aberrations induced by inhibiting topo II takes place: lack of chromosome segregation, undercondensation, lack of sister chromatid resolution, and lack of chromosome individualization.