Withaferin A Causes FOXO3a- and Bim-Dependent Apoptosis and Inhibits Growth of Human Breast Cancer Cells In vivo

Abstract

Withaferin A (WA) is derived from the medicinal plant Withania somnifera, which has been safely used for centuries in Indian Ayurvedic medicine for treatment of different ailments. We now show, for the first time, that WA exhibits significant activity against human breast cancer cells in culture and in vivo. The WA treatment decreased viability of MCF-7 (estrogen-responsive) and MDA-MB-231 (estrogenindependent) human breast cancer cells in a concentrationdependent manner. The WA-mediated suppression of breast cancer cell viability correlated with apoptosis induction characterized by DNA condensation, cytoplasmic histone-associated DNA fragmentation, and cleavage of poly-(ADP-ribose)-polymerase. On the other hand, a spontaneously immortalized normal mammary epithelial cell line (MCF-10A) was relatively more resistant to WA-induced apoptosis compared with breast cancer cells. The WAmediated apoptosis was accompanied by induction of Bim-s and Bim-L in MCF-7 cells and induction of Bim-s and Bim-EL isoforms in MDA-MB-231 cells. The cytoplasmic histone-associated DNA fragmentation resulting from WA exposure was significantly attenuated by knockdown of protein levels of Bim and its transcriptional regulator FOXO3a in both cell lines. Moreover, FOXO3a knockdown conferred marked protection against WA-mediated induction of Bim-s expression. The growth of MDA-MB-231 cells implanted in female nude mice was significantly retarded by 5 weekly i.p. injections of 4 mg WA/kg body weight. The tumors from WA-treated mice exhibited reduced cell proliferation and increased apoptosis compared with tumors from control mice. These results point toward an important role of FOXO3a and Bim in regulation of WA-mediated apoptosis in human breast cancer cells. [Cancer Res 2008;68(18):7661-9]

Withaferin A inhibits breast cancer invasion and metastasis at sub‐cytotoxic doses by inducing vimentin disassembly and serine 56 phosphorylation

“…Tumor growth inhibition at this dose is consistent with a previous report showing a role of FOXO3A and Bim in the regulation of WFA-mediated apoptosis. 27 As the maximum dose of WFA (4 mg/kg) had minimal toxicity to normal tissue (Fig. 5), we suspect that greater WFA concentrations are safe with potentially greater antimetastatic and cytotoxic efficacy.…”

“…1a), consistent with previous reports. 27,28 In almost all cases, concentrations less than 500 nM had a negligible effect on proliferation. The apoptotic activity of WFA was assessed using cleaved PARP in MDA-MB 231 breast cancer cells and H1299 lung cancer cell lines.…”

“…25 Moreover, WFA has proapoptotic and anti-tumor activity in breast and prostate cancers. [26][27][28] There are several other documented targets of WFA including NF-Kb, BCL-2, FOXO3A, Hsp90, phosphorylated STAT3 and annexin II 27,[29][30][31][32][33] ; however, the mechanisms by which this leads to anti-tumor activity are not fully understood.…”

Simultaneous inhibition of the ubiquitin-proteasome system and autophagy enhances apoptosis induced by ER stress aggravators in human pancreatic cancer cells

“…WA was dissolved in vehicle (10% DMSO, 40% cremophor:ethanol (3:1), and 50% PBS). 48 Tumor size and body weight were measured every 2 d from d 21 after implantation. The tumor volume was calculated by the formula: volume (mm 3 ) D (length £ width 2 )/2.…”

Combination of withaferin A and X-ray irradiation enhances apoptosis in U937 cells

“…Several studies have been reported for its anti-tumor effects, including the inhibitory activities of tumor cell growth, angiogenesis and metastasis (Stan et al, 2008a;Mohan et al, 2004). Recently, a variety of biological roles of Wit A have been reported; induction of apoptosis by ROS generation (Malik et al, 2007;Lee et al, 2009), anti-proliferative effect of Wit A by G2/ M phase cell cycle arrest (Stan et al, 2008b), inhibition of cell adhesion molecules by inactivation of Akt and NF-jB (Oh and Kwon, 2009), and inhibition of cell migration/invasion through down-regulation of signal transducer and activator of transcription 3 (STAT3) activation in human breast cancer cells (Lee et al, 2010).…”