Withaferin A modulates the Spindle assembly checkpoint by degradation of Mad2-Cdc20 complex in colorectal cancer cell lines

Biochem Pharmacol. 2014 Sep 1;91(1):31-9. doi: 10.1016/j.bcp.2014.06.022. Epub 2014 Jul 1.

Abstract

Withania somnifera L. Dunal (Ashwagandha) is used over centuries in the ayurvedic medicines in India. Withaferin A, a withanolide, is the major compound present in leaf extract of the plant which shows anticancer activity against leukemia, breast cancer and colorectal cancer. It arrests the ovarian cancer cells in the G2/M phase in dose dependent manner. In the current study we show the effect of Withaferin A on cell cycle regulation of colorectal cancer cell lines HCT116 and SW480 and its effect on cell fate. Treatment of these cells with this compound leads to apoptosis in a dose dependent manner. It causes the G2/M arrest in both the cell lines. We show that Withaferin A (WA) causes mitotic delay by blocking Spindle assembly checkpoint (SAC) function. Apoptosis induced by Withaferin A is associated with proteasomal degradation of Mad2 and Cdc20, an important constituent of the Spindle Checkpoint Complex. Further overexpression of Mad2 partially rescues the deleterious effect of WA by restoring proper anaphase initiation and keeping more number of cells viable. We hypothesize that Withaferin A kills cancer cells by delaying the mitotic exit followed by inducing chromosome instability.

Keywords: Cdc20; Chromosome instability; Mad2; Spindle assembly checkpoint; Withaferin A.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents, Phytogenic / pharmacology
  • Apoptosis / drug effects
  • Cdc20 Proteins / metabolism*
  • Cell Line, Tumor / drug effects
  • Chromosome Aberrations
  • Colorectal Neoplasms / drug therapy*
  • Colorectal Neoplasms / metabolism
  • Colorectal Neoplasms / pathology
  • G2 Phase Cell Cycle Checkpoints / drug effects
  • HCT116 Cells / drug effects
  • Humans
  • M Phase Cell Cycle Checkpoints / drug effects
  • Mad2 Proteins / metabolism*
  • Proteasome Endopeptidase Complex / metabolism
  • Spindle Apparatus / drug effects*
  • Withanolides / pharmacology*

Substances

  • Antineoplastic Agents, Phytogenic
  • Cdc20 Proteins
  • MAD2L1 protein, human
  • Mad2 Proteins
  • Withanolides
  • CDC20 protein, human
  • Proteasome Endopeptidase Complex
  • withaferin A