Abstract
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 language | English |
|---|---|
| Pages (from-to) | 191-198.e3 |
| Journal | Molecular Cell |
| Volume | 79 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 02 Jul 2020 |
Keywords
- 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