Two antagonistic microtubule targeting drugs act synergistically to kill cancer cells

Abstract

Phone number +33(0)4 24 76 54 95 71 laurence.lafanechere@univ-grenoble-alpes.fr 25 2 Running title: A new paclitaxel sensitizer that targets tubulin 26 Scientific Research (NWO) CW ECHO grant (711.015.005) to AA. 32 33 The authors declare no potential conflicts of interest 34 35 Word count: 36 Abstract: 158 words 37 Main manuscript, including acknowledgments: 4667 words 38 Figure legends: 1115 words 39 Number of references: 34 40 Abstract 43Paclitaxel is a microtubule stabilizing agent and a successful drug for cancer chemotherapy 44 inducing, however, adverse effects. To reduce the effective dose of paclitaxel, we searched 45 for drugs which could potentiate its therapeutic effect. We have screened a chemical library 46 3 and selected Carba1, a carbazolone, which exerts synergistic cytotoxic effects on tumor cells 47 grown in vitro, when co-administrated with a low dose of paclitaxel. Carba1 targets the 48 colchicine binding-site of tubulin and is a microtubule-destabilizing agent. The Carba1-49 induced modulation of microtubule dynamics increases the accumulation of fluorescent 50 paclitaxel inside microtubules, providing a mechanistic explanation of the observed synergy 51 between Carba1 and paclitaxel. The synergistic effect of Carba1 with paclitaxel on tumor cell 52 viability was also observed in vivo in xenografted mice. Thus, a new mechanism favoring 53 paclitaxel accumulation in microtubules can be transposed to in vivo mouse cancer treatments, 54 paving the way for new therapeutic strategies combining low doses of microtubule targeting 55 agents with opposite mechanisms of action. 56 Introduction 57 Microtubules (MTs), dynamic polymeric filaments composed of -tubulin and -tubulin 58 heterodimers, are key components of the cytoskeleton of eukaryotic cells. Their crucial roles 59 in cell division and physiology mainly rely on their ability to rapidly polymerize or 60 depolymerize. Targeted perturbation of this finely tuned process constitutes a major 61 therapeutic strategy. Drugs interfering with MTs are major constituents of chemotherapies for 62 the treatment of carcinomas. A number of compounds bind to the tubulin-MT system. They 63 can be roughly classified into MT-stabilizers such as taxanes or epothilones, and MT-64 destabilizers such as vinca alkaloids, combretastatin and colchicine [1]. It has been 65 demonstrated that binding of vinca alkaloids or colchicine prevents the curved-to-straight 66 conformational change of tubulin at the tip of the growing MT, necessary for proper 67 incorporation of new tubulin dimers into the MT lattice (see reviews [1,2]). 68 Paclitaxel (PTX) binds to the taxane-site of -tubulin and stabilizes the MT lattice by 69 strengthening lateral and/or longitudinal tubulin contacts within the MT [1]. At stoichiometric 70 concentrations, it promotes MT assembly. At low and clinically relevant concentrations, PTX 71

ATIP3 deficiency facilitates intracellular accumulation of paclitaxel to reduce cancer cell migration and lymph node metastasis in breast cancer patients

“…Paclitaxel accumulates close to microtubule ends and may then propagate in microtubule lattices 23 . In line with these studies it was recently shown that Carba1, a microtubule-destabilizing agent that modifies plus ends dynamics by increasing catastrophes, synergizes with low doses of paclitaxel by facilitating the incorporation of paclitaxel on the microtubule shaft 24 .…”

Role of microtubule dynamics in Wallerian degeneration and nerve regeneration after peripheral nerve injury

“…It is well-known that microtubules play pivotal roles in most cellular activities, and that microtubule dynamics are crucial to their (Zhang et al, 2015;Fedorov et al, Microtubule-targeting agents are used in the treatment of various diseases to stabilize or destabilize microtubules for therapeutic effect (Kaul et al, 2019;Peronne et al, 2020). To date, however, there have been no reports of the role of microtubule dynamics in WD after PNI.…”