Ayurvedic Medicine Constituent Withaferin A Causes G2 and M Phase Cell Cycle Arrest in Human Breast Cancer Cells

Abstract

Withaferin A (WA) is derived from the medicinal plant Withania somnifera that has been safely used for centuries in the Indian Ayurvedic medicine for treatment of various ailments. We now demonstrate that WA treatment causes G2 and mitotic arrest in human breast cancer cells. Treatment of MDA-MB-231 (estrogen-independent) and MCF-7 (estrogen-responsive) cell lines with WA resulted in a concentration-and time-dependent increase in G2-M fraction, which correlated with a decrease in levels of cyclin-dependent kinase 1 (Cdk1), cell division cycle 25B (Cdc25B) and/or Cdc25C proteins leading to accumulation of Tyr15 phosphorylated (inactive) Cdk1. Ectopic expression of Cdc25C conferred partial yet significant protection against WA-mediated G2-M phase cell cycle arrest in MDA-MB-231 cells. The WA-treated MDA-MB-231 and MCF-7 cells were also arrested in mitosis as judged by fluorescence microscopy and analysis of Ser10 phosphorylated histone H3. Mitotic arrest resulting from exposure to WA was accompanied by an increase in the protein level of anaphase promoting complex/cyclosome substrate securin. In conclusion, the results of the present study suggest that G2-M phase cell cycle arrest may be an important mechanism in anti-proliferative effect of WA against human breast cancer cells.

Anti-cancer activity of withaferin A in B-cell lymphoma

“…14,18,20,30 Accordingly we also found that WA treatment resulted in decreased expression of CDK1 but not cyclin B1 in both LY-10 and LY-3 cells lines, which may lead to G 2 /M phase arrest. Results of WA treatment on SudHL-6 cells were consistent with the G 2 /M phase arrest seen in melanoma, glioblastoma, and cervical cancer cells.…”

“…14 Several studies found that WA stimulates apoptosis through restoring p53 levels and thus activating Bax and other pro-apoptotic Bcl-2 family proteins to induce apoptosis of cervical cancer cells, 18 or by enhancing levels of the proapoptotic factor, Par-4, and downstream caspase activation in prostate cancer cells. 19 In most cancer cell lines WA inhibits the proliferation of tumor cells through a G 2 /M phase cell cycle arrest, 20 and inhibits the activation of NF-kB via interaction with the IKKg subunit preventing IkB phosphorylation. 21,22 In pancreatic cancer cells, Yu et.…”

In vitro protective effects of Withania somnifera (L.) dunal root extract against hydrogen peroxide and β‐amyloid(1–42)‐induced cytotoxicity in differentiated PC12 cells

“…After H 2 O 2 exposure for 24 h, 50 -80 % cell viability was observed at extract concentrations from 6.11 µg/mL to 100 µg/mL, compared with the negative control (H 2 O 2 alone), with 50 and 100 µg/mL extract concentrations showing the greatest improvement compared with the negative control (p<0.001). At the highest extract concentration (200 µg/mL) the cytoprotective effects were abolished, due, perhaps, to direct cytotoxic and antiproliferative properties of W. somnifera being expressed at high concentrations (Sabbaraju et al, 2006;Stan et al, 2008). .…”

Pirarubicin inhibits multidrug-resistant osteosarcoma cell proliferation through induction of G2/M phase cell cycle arrest

“…The eukaryotic cell cycle is strictly regulated by a class of cyclins and cyclindependent kinases (CDKs) [31] . The progression from G 2 to mitosis is controlled by the mitosispromoting factor, which comprises a complex of Cdc2 (CDK1) and cyclin B [32][33][34][35] . During G 2 /M transition, CDK1 activation requires an association with cyclin B1 and phosphorylation at Thr 161 by CDK-activating kinase (CAK), whereas the CDK1/ cyclin B complex is kept inactive by phosphorylation on Thr 14 or Tyr 15 of CDK1 by kinase Wee1 and Myt1 [36] .…”