Pharmaceutical-Grade Rigosertib Is a Microtubule-Destabilizing Agent

Marco Jost, Yuwen Chen, Luke A Gilbert, Max A Horlbeck, Lenno Krenning, Grégory Menchon, Ankit Rai, Min Y Cho, Jacob J Stern, Andrea E Prota, Martin Kampmann, Anna Akhmanova, Michel O Steinmetz, Marvin E Tanenbaum, Jonathan S Weissman

Research output: Contribution to journal/periodicalArticleScientificpeer-review

15 Citations (Scopus)


We recently used CRISPRi/a-based chemical-genetic screens and cell biological, biochemical, and structural assays to determine that rigosertib, an anti-cancer agent in phase III clinical trials, kills cancer cells by destabilizing microtubules. Reddy and co-workers (Baker et al., 2020, this issue of Molecular Cell) suggest that a contaminating degradation product in commercial formulations of rigosertib is responsible for the microtubule-destabilizing activity. Here, we demonstrate that cells treated with pharmaceutical-grade rigosertib (>99.9% purity) or commercially obtained rigosertib have qualitatively indistinguishable phenotypes across multiple assays. The two formulations have indistinguishable chemical-genetic interactions with genes that modulate microtubule stability, both destabilize microtubules in cells and in vitro, and expression of a rationally designed tubulin mutant with a mutation in the rigosertib binding site (L240F TUBB) allows cells to proliferate in the presence of either formulation. Importantly, the specificity of the L240F TUBB mutant for microtubule-destabilizing agents has been confirmed independently. Thus, rigosertib kills cancer cells by destabilizing microtubules, in agreement with our original findings.

Original languageEnglish
Pages (from-to)191-198.e3
JournalMolecular Cell
Issue number1
Publication statusPublished - 02 Jul 2020


  • Antineoplastic Agents/pharmacology
  • Cell Proliferation
  • Cells, Cultured
  • Crystallography, X-Ray
  • Drug Contamination
  • Glycine/analogs & derivatives
  • Humans
  • Microtubules/drug effects
  • Mutation
  • Neoplasms/drug therapy
  • Pharmaceutical Preparations/chemistry
  • Protein Conformation
  • Sulfones/pharmacology
  • Tubulin/chemistry


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