Molecular mechanisms of the antitumor activity of SB225002: a novel microtubule inhibitor

Biochem Pharmacol. 2013 Jun 15;85(12):1741-52. doi: 10.1016/j.bcp.2013.04.011. Epub 2013 Apr 20.


SB225002 (SB) is an IL-8 receptor B (IL-8RB) antagonist that has previously been shown to inhibit IL-8-based cancer cell invasion, and to possess in vivo anti-inflammatory and anti-nociceptive effects. The present study presented an evidence for the cell cycle-targeting activity of SB in a panel of p53-mutant human cancer cell lines of different origin, and investigated the underlying molecular mechanisms. A combination of cell cycle analysis, immunocytometry, immunoblotting, and RNA interference revealed that SB induced a BubR1-dependent mitotic arrest. Mechanistically, SB was shown to possess a microtubule destabilizing activity evidenced by hyperphosphorylation of Bcl2 and BclxL, suppression of microtubule polymerization and induction of a prometaphase arrest. Molecular docking studies suggested that SB has a good affinity toward vinblastine-binding site on β-tubulin subunit. Of note, SB265610 which is a close structural analog of SB225002 with a potent IL-8RB antagonistic activity did not exhibit a similar antimitotic activity. Importantly, in P-glycoprotein overexpressing NCI/Adr-Res cells the antitumor activity of SB was unaffected by multidrug resistance. Interestingly, the mechanisms of SB-induced cell death were cell-line dependent, where in invasive hepatocellular carcinoma HLE cells the significant contribution of BAK-dependent mitochondrial apoptosis was demonstrated. Conversely, SB activated p38 MAPK signaling in colorectal adenocarcinoma cells SW480, and pharmacologic inhibition of p38 MAPK activity revealed its key role in mediating SB-induced caspase-independent cell death. In summary, the present study introduced SB as a promising antitumor agent which has the potential to exert its activity through dual mechanisms involving microtubules targeting and interference with IL-8-drivin cancer progression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Cell Survival / physiology
  • Humans
  • Microtubules / drug effects*
  • Microtubules / metabolism
  • Phenylurea Compounds / chemistry
  • Phenylurea Compounds / pharmacology*
  • Receptors, Interleukin-8 / antagonists & inhibitors
  • Receptors, Interleukin-8 / metabolism
  • Tubulin Modulators / chemistry
  • Tubulin Modulators / pharmacology*
  • U937 Cells


  • Antineoplastic Agents
  • Phenylurea Compounds
  • Receptors, Interleukin-8
  • SB 225002
  • Tubulin Modulators