Selective Killing of Cancer Cells by Ashwagandha Leaf Extract and Its Component Withanone Involves ROS Signaling

Abstract

Background and PurposeAshwagandha is a popular Ayurvedic herb used in Indian traditional home medicine. It has been assigned a variety of health-promoting effects of which the mechanisms remain unknown. We previously reported the selective killing of cancer cells by leaf extract of Ashwagandha (i-Extract) and its purified component Withanone. In the present study, we investigated its mechanism by loss-of-function screening (abrogation of i-Extract induced cancer cell killing) of the cellular targets and gene pathways.Methodology/Principal FindingsRandomized ribozyme library was introduced into cancer cells prior to the treatment with i-Extract. Ribozymes were recovered from cells that survived the i-Extract treatment. Gene targets of the selected ribozymes (as predicted by database search) were analyzed by bioinformatics and pathway analyses. The targets were validated for their role in i-Extract induced selective killing of cancer cells by biochemical and molecular assays. Fifteen gene-targets were identified and were investigated for their role in specific cancer cell killing activity of i-Extract and its two major components (Withaferin A and Withanone) by undertaking the shRNA-mediated gene silencing approach. Bioinformatics on the selected gene-targets revealed the involvement of p53, apoptosis and insulin/IGF signaling pathways linked to the ROS signaling. We examined the involvement of ROS-signaling components (ROS levels, DNA damage, mitochondrial structure and membrane potential) and demonstrate that the selective killing of cancer cells is mediated by induction of oxidative stress.ConclusionAshwagandha leaf extract and Withanone cause selective killing of cancer cells by induction of ROS-signaling and hence are potential reagents that could be recruited for ROS-mediated cancer chemotherapy.

Effect of Withania somnifera (Ashwagandha) on the Development of Chemotherapy-Induced Fatigue and Quality of Life in Breast Cancer Patients

“…35 In another cell culture assay, WS showed selective killing of cancers by reactive oxygen species-mediated pathways. 17 In our study, we observed similar overall survival figures among WS-treated patients, though the trend is in favor of the study arm. The favorable trend may be by chance or difference in disease load or higher number of HER-2 positive patients in the control arm.…”

Withanone-Rich Combination of Ashwagandha Withanolides Restricts Metastasis and Angiogenesis through hnRNP-K

“…It was shown that withaferin A inhibits prometastatic intermediate filament protein-vimentin, an epithelial-to-mesenchymal transition (EMT) signaling protein (5, 32), pAkt signaling pathway and MMP9 (33), STAT3 and its downstream effectors Bcl-xL, Bcl-2, cyclin D1 (34), pAkt and pERK signaling (2), oncogenic transcription factor STAT3 (35), and NF-kB (36). It was shown to induce extracellular proapoptotic tumor suppressor protein, Par-4 (2), oxidative stress to cancer cells (37)(38)(39). Despite of these beneficial anticancer effects, cytotoxicity of withaferin A, in high dose, to normal human cells has been a concern (7,8,40).…”

Preventive role of <i>Withania somnifera</i> on hyperlipidemia and cardiac oxidative stress in streptozotocin induced type 2 diabetic rats

“…Several studies on this plant revealed that it possesses anti-inflammatory, anti-tumor, anti-stress, anti-oxidant, immunomodulatory, hematopoietic and rejuvenating properties besides its positive influence on the endocrine, cardiopulmonary and central nervous system [9,10]. Recently we have published the protective effect of Withania somnifera against oxidative stress and pancreatic β-cell damage in type 2 diabetic rats [11].…”