Metabolic alterations in mammary cancer prevention by withaferin A in a clinically relevant mouse model

Withaferin A decreases glycolytic reprogramming in breast cancer

Reprogrammed glucose metabolism is considered as the hallmark of cancer with therapeutic implications. Phytocompounds have potential to inhibit cancer metabolism. Here, we tested the ability of Withaferin A (WA), a withanolide derived from Withania somnifera, in modulating cancer metabolism. The assessed effect of WA on aerobic glycolysis in breast cancer cell lines showed that WA decreases the glucose uptake, lactate production and ATP generation by inhibiting the expression of key glycolytic enzymes i.e., GLUT1, HK2 and PKM2. We also identified that WA induced inhibition of cancer glycolysis by targeting c-myc as validated by silencing experiments followed by metabolic readouts. Decreased glycolysis resulted in reduced cell viability, biomass and colony forming ability of breast cancer cells. To further validate our in vitro findings in breast cancer patients, we analyzed 90 metabolic pathways in ~ 2000 breast tumors and observed that glycolysis is the most deregulated pathway in breast tumors. Deregulated glycolysis also predicted poor prognosis in breast cancer patients. In addition, patient data showed correlation between c-myc expression and glycolytic deregulation in breast cancer. Taken together, our results highlight the role of WA in inhibiting breast cancer metabolism via c-myc/glycolysis axis.

Therapeutic and pharmacological efficacy of plant-derived bioactive compounds in targeting breast cancer

Breast cancer (BC) ranks number one among cancers affecting women globally. Serious concerns include delayed diagnosis, poor prognosis, and adverse side effects of conventional treatment, leading to residual morbidity. Therefore, an alternative treatment approach that is safe and effective has become the need of the hour. In this regard, plant-based medicines via a combination of conventional drugs are gaining increasing acceptance worldwide, playing a pivotal role in cancer management as proven by their efficacy evaluation studies. This review aims to fill the knowledge gaps by providing the preclinical evidence of cellular and molecular mechanisms of Indian phytomedicines in targeting varied pathways of breast cancer progression. A comprehensive search was performed on different platforms, followed by screening of relevant studies for review. In this article, the in-depth of various botanical drugs covering their nomenclature, dosage, toxicity, and modus operandi in BC cells have been extensively discussed. Various signaling pathways like Notch signaling, MAPK signaling, apoptosis, Wnt signaling, etc. regulated by herbal medicine treatment in BC are also highlighted to understand the drug mechanism better. This will guide the researchers to plan future strategies and generate more robust integrated evidence of plant-based drugs or botanical formulations for their potential role in the management of BC.

Withanolides: Promising candidates for cancer therapy

Natural products have played a significant role throughout history in the prevention and treatment of numerous diseases, particularly cancers. As a natural product primarily derived from various medicinal plants in the Withania genus, withanolides have been shown in several studies to exhibit potential activities in cancer treatment. Consequently, understanding the molecular mechanism of withanolides could herald the discovery of new anticancer agents. Withanolides have been studied widely, especially in the last 20 years, and attracted the attention of numerous researchers. Currently, over 1200 withanolides have been classified, with approximately a quarter of them having been reported in the literature to be able to modulate the survival and death of cancer cells through multiple avenues. To what extent, though, has the anticancer effects of these compounds been studied? How far are they from being developed into clinical drugs? What are their potential, characteristic features, and challenges? In this review, we elaborate on the current knowledge of natural compounds belonging to this class and provide an overview of their natural sources, anticancer activity, mechanism of action, molecular targets, and implications for anticancer drug research. In addition, direct targets and clinical research to guide the design and implementation of future preclinical and clinical studies to accelerate the application of withanolides have been highlighted.

AS1411 aptamer tagged PEGylated liposomes as a smart nanocarrier for tumor-specific delivery of Withaferin A for mitigating pulmonary metastasis

Metastasis is the most challenging health problem contributing to about 90 % of cancer-related deaths worldwide. Metastatic tumors are highly aggressive and resistant to the most available therapeutic options. Hence, innovative therapeutic approaches are required to target metastatic tumors selectively. In this study, we prepared AS1411 functionalized Withaferin A loaded PEGylated nanoliposomes (ALW) and investigated its therapeutic effect in B16F10 induced in pulmonary metastasis mice models. The prepared formulations' size and morphological properties were evaluated using dynamic light scattering system and Transmission electron microscope. ALW had spherical-shaped nanosized particles with a size of 118 nm and an encapsulation efficacy of 82.5 %. TEM analysis data indicated that ALW has excellent dispersibility and uniform spherical nano-size particles. ALW inhibited cell viability, and induced cell apoptosis of B16F10. In vivo, the pulmonary metastasis study in C57BL/6 mice revealed that the ALW significantly (p < 0.01) improved the encapsulated WA anti-metastatic activity and survival rate compared to WA or LW treated groups. ALW significantly (p < 0.01) downregulated the levels of IL-6, TNF-α, and IL-1β and significantly reduced the lung collagen hydroxyproline, hexosamine, and uronic acid content in metastatic tumor bearing animals compared to WA or LW. Gene expression levels of MMPs and NF-κB were downregulated in ALW treated metastatic pulmonary tumor-bearing mice. These findings demonstrate that the AS1411 functionalized Withaferin A loaded PEGylated nanoliposomes could be a promising nanoliposomal formulation for targeting metastatic tumors.

Molecular targets and mechanisms of anti-cancer effects of withanolides

Withanolides are a class of natural products with a steroidal lactone structure that exhibit a broad spectrum of anti-cancer effects. To date, several studies have shown that their possible mechanisms in cancer development and progression are associated with the regulation of cell proliferation, apoptosis, metastasis, and angiogenesis. Withanolides can also attenuate inflammatory responses, as well as modulate the genomic instability and energy metabolism of cancer cells. In addition, they may improve the safety and efficacy of cancer treatments as adjuvants to traditional cancer therapeutics. Herein, we summarize the molecular targets and mechanisms of withanolides in different cancers, as well as their current clinical studies on them.

Withaferin A inhibits breast cancer-induced osteoclast differentiation

Bone is the most prone to metastatic spread of breast cancer cells for each subtype of the disease. Bone metastasis-related complications including severe pain and pathological fractures affect patients' quality of life. Current treatment options including surgery, radiation, and bone-targeted therapies (e.g., bisphosphonates) are costly or have serious adverse effects such as renal toxicity and osteonecrosis of the jaws. Therefore, a safe, inexpensive, and efficacious agent for prevention of breast cancer bone metastasis is urgently needed. Our previously published RNA sequencing analysis revealed that many genes implicated in bone remodeling and breast cancer bone metastasis were significantly downregulated by treatment with withaferin A (WA), which is a promising cancer chemopreventive agent derived from a medicinal plant (Withania somnifera). The present study investigated whether WA inhibits breast cancer induction of osteoclast differentiation. At plasma achievable doses, WA treatment inhibited osteoclast differentiation (osteoclastogenesis) induced by three different subtypes of breast cancer cells (MCF-7, SK-BR-3, and MDA-MB-231). WA and the root extract of W. somnifera were equally effective for inhibition of breast cancer induction of osteoclast differentiation. This inhibition was accompanied by suppression of interleukin (IL)-6, IL-8, and receptor activator of nuclear factor-κB ligand, which are pivotal osteoclastogenic cytokines. The expression of runt-related transcription factor 2, nuclear factor-κB, and SOX9 transcription factors, which positively regulate osteoclastogenesis, was decreased in WA-treated breast cancer cells as revealed by confocal microscopy and/or immunoblotting. Taken together, these data suggest that WA could be a promising agent for prevention of breast cancer-induced bone metastasis.

Withaferin A Inhibits Fatty Acid Synthesis in Rat Mammary Tumors

Withaferin A (WA), which is a small molecule derived from a medicinal plant (Withania somnifera), inhibits growth of human breast cancer xenografts and mammary tumor development in rodent models without any toxicity. However, the mechanism underlying inhibition of mammary cancer development by WA administration is not fully understood. Herein, we demonstrate that the fatty acid synthesis pathway is a novel target of WA in mammary tumors. Treatment of MCF-7 and MDA-MB-231 cells with WA resulted in suppression of fatty acid metabolizing enzymes, including ATP-citrate lyase (ACLY), acetyl-CoA carboxylase 1 (ACC1), fatty acid synthase (FASN), and carnitine palmitoyltransferase 1A (CPT1A). Expression of FASN and CPT1A was significantly higher in N-methyl-N-nitrosourea-induced mammary tumors in rats when compared with normal mammary tissues. WA-mediated inhibition of mammary tumor development in rats was associated with a statistically significant decrease in expression of ACC1 and FASN and suppression of plasma and/or mammary tumor levels of total free fatty acids and phospholipids. WA administration also resulted in a significant increase in percentage of natural killer cells in the spleen. The protein level of sterol regulatory element binding protein 1 (SREBP1) was decreased in MDA-MB-231 cells after WA treatment. Overexpression of SREBP1 in MDA-MB-231 cells conferred partial but significant protection against WA-mediated downregulation of ACLY and ACC1. In conclusion, circulating and/or mammary tumor levels of fatty acid synthesis enzymes and total free fatty acids may serve as biomarkers of WA efficacy in future clinical trials.

PREVENTION RELEVANCE

The present study shows that breast cancer prevention by WA in rats is associated with suppression of fatty acid synthesis.

How Should the Worldwide Knowledge of Traditional Cancer Healing Be Integrated with Herbs and Mushrooms into Modern Molecular Pharmacology?

Traditional herbal medicine (THM) is a "core" from which modern medicine has evolved over time. Besides this, one third of people worldwide have no access to modern medicine and rely only on traditional medicine. To date, drugs of plant origin, or their derivates (paclitaxel, vinblastine, vincristine, vinorelbine, etoposide, camptothecin, topotecan, irinotecan, and omacetaxine), are very important in the therapy of malignancies and they are included in most chemotherapeutic regimes. To date, 391,000 plant and 14,000 mushroom species exist. Their medical and biochemical capabilities have not been studied in detail. In this review, we systematized the information about plants and mushrooms, as well as their active compounds with antitumor properties. Plants and mushrooms are divided based on the regions where they are used in ethnomedicine to treat malignancies. The majority of their active compounds with antineoplastic properties and mechanisms of action are described. Furthermore, on the basis of the available information, we divided them into two priority groups for research and for their potential of use in antitumor therapy. As there are many prerequisites and some examples how THM helps and strengthens modern medicine, finally, we discuss the positive points of THM and the management required to transform and integrate THM into the modern medicine practice.

Withania somnifera Modulates Radiation-Induced Generation of Lung Cancer Stem Cells via Restraining the Hedgehog Signaling Factors

Cancer stem cells (CSCs) are implicated in the genesis, development, and recurrence of lung cancer (LC) with great resistance to radiation and chemotherapy. The aim of this study is to assess the inhibitory potential of ethanol extract of Withania somnifera (WS); 500 mg/kg body-weight/day and 8 Gy of ionizing radiation (IR) could inhibit the stemness gene and confer the radiosensitizing effect of W. somnifera extract in the female rat LC model. Compared to IR or WS, the in vitro assay showed that WS + IR potentiates proliferation-inhibition and cell death of the A-549 cell line and suppresses sphere formation. The Hedgehog (Hh) signaling associated with the expression levels of lung CSC markers, octamer-binding transcription factor-4 (OCT4), SRY-box 2 (SOX2), CD133, ATP Binding Cassette Subfamily G Member 2 (ABCG2), and NANOG was upregulated with stimulated epithelial-to-mesenchymal transition (EMT) indicators α-smooth muscle actin (α-SMA), Drosophila embryonic protein (SNAIL-1), Vimentin, and E-cadherin in the LC rat model. The W. somnifera extract plus IR inhibits Hh activation factors, which has resulted in the suppression of CSC gene markers and EMT factors. W. somnifera extract may be a significant adjuvant in the course of radiotherapy, contributing to the termination of tumor progression, and thus providing cure insights into the molecular mechanisms of lung CSCs intervention.

Effects and mechanisms of dietary bioactive compounds on breast cancer prevention

Breast cancer (BC) is the most often diagnosed cancer among females globally and has become an increasing global health issue over the last decades. Despite the substantial improvement in screening methods for initial diagnosis, effective therapy remains lacking. Still, there has been high recurrence and disease progression after treatment of surgery, endocrine therapy, chemotherapy, and radiotherapy. Considering this view, there is a crucial requirement to develop safe, freely accessible, and effective anticancer therapy for BC. The dietary bioactive compounds as auspicious anticancer agents have been recognized to be active and their implications in the treatment of BC with negligible side effects. Hence, this review focused on various dietary bioactive compounds as potential therapeutic agents in the prevention and treatment of BC with the mechanisms of action. Bioactive compounds have chemo-preventive properties as they inhibit the proliferation of cancer cells, downregulate the expression of estrogen receptors, and cell cycle arrest by inducing apoptotic settings in tumor cells. Therapeutic drugs or natural compounds generally incorporate engineered nanoparticles with ideal sizes, shapes, and enhance their solubility, circulatory half-life, and biodistribution. All data of in vitro, in vivo, and clinical studies of dietary bioactive compounds and their impact on BC were collected from Science Direct, PubMed, and Google Scholar. The data of chemopreventive and anticancer activity of dietary bioactive compounds were collected and orchestrated in a suitable place in the review. These shreds of data will be extremely beneficial to recognize a series of additional diet-derived bioactive compounds to treat BC with the lowest side effects.

Leelamine suppresses cMyc expression in prostate cancer cells in vitro and inhibits prostate carcinogenesis in vivo

Aim

Leelamine (LLM) inhibits growth of human prostate cancer cells but the underlying mechanism is not fully understood. The present study was undertaken to determine the effect of LLM on cMyc, which is overexpressed in a subset of human prostate cancers.

Methods

The effect of LLM on cMyc expression and activity was determined by western blotting/confocal microscopy and luciferase reporter assay, respectively. A transgenic mouse model of prostate cancer (Hi-Myc) was used to determine chemopreventive efficacy of LLM.

Results

Exposure of androgen sensitive (LNCaP) and castration-resistant (22Rv1) human prostate cancer cells to LLM resulted in downregulation of protein and mRNA levels of cMyc. Overexpression of cMyc partially attenuated LLM-mediated inhibition of colony formation, cell viability, and cell migration in 22Rv1 and/or PC-3 cells. LLM treatment decreased protein levels of cMyc targets (e.g., lactate dehydrogenase), however, overexpression of cMyc did not attenuate these effects. A trend for a decrease in expression level of cMyc protein was discernible in 22Rv1 xenografts from LLM-treated mice compared with control mice. The LLM treatment (10 mg/kg body weight, 5 times/week) was well-tolerated by Hi-Myc transgenic mice. The incidence of high-grade prostatic intraepithelial neoplasia, adenocarcinoma in situ, and microinvasion was lower in LLM-treated Hi-Myc mice but the difference was not statistically significant.

Conclusion

The present study reveals that LLM inhibits cMyc expression in human prostate cancer cells in vitro but concentrations higher than 10 mg/kg may be required to achieve chemoprevention of prostate cancer.

Withania somnifera (L.) Dunal (Ashwagandha): A comprehensive review on ethnopharmacology, pharmacotherapeutics, biomedicinal and toxicological aspects

Withania somnifera (L.) Dunal (Solanaceae) has been used as a traditional Rasayana herb for a long time. Traditional uses of this plant indicate its ameliorative properties against a plethora of human medical conditions, viz. hypertension, stress, diabetes, asthma, cancer etc. This review presents a comprehensive summary of the geographical distribution, traditional use, phytochemistry, and pharmacological activities of W. somnifera and its active constituents. In addition, it presents a detailed account of its presence as an active constituent in many commercial preparations with curative properties and health benefits. Clinical studies and toxicological considerations of its extracts and constituents are also elucidated. Comparative analysis of relevant in-vitro, in-vivo, and clinical investigations indicated potent bioactivity of W. somnifera extracts and phytochemicals as anti-cancer, anti-inflammatory, apoptotic, immunomodulatory, antimicrobial, anti-diabetic, hepatoprotective, hypoglycaemic, hypolipidemic, cardio-protective and spermatogenic agents. W. somnifera was found to be especially active against many neurological and psychological conditions like Parkinson's disease, Alzheimer's disease, Huntington's disease, ischemic stroke, sleep deprivation, amyotrophic lateral sclerosis, attention deficit hyperactivity disorder, bipolar disorder, anxiety, depression, schizophrenia and obsessive-compulsive disorder. The probable mechanism of action that imparts the pharmacological potential has also been explored. However, in-depth studies are needed on the clinical use of W. somnifera against human diseases. Besides, detailed toxicological analysis is also to be performed for its safe and efficacious use in preclinical and clinical studies and as a health-promoting herb.

Review on anticancerous therapeutic potential of Withania somnifera (L.) Dunal

ETHNOPHARMACOLOGICAL RELEVANCE

Withania somnifera, commonly known as Ashwagandha, is an important medicinal herb belonging to family Solanaceae. It is widely used in folkloric and Ayurvedic medicines since antiquity. Traditionally, the plant is highly practiced throughout the globe as immunomodulator, anti-inflammatory, anti-stress, anti-parkinson, anti-alzheimer, cardio protective, neural and physical health enhancer, neurodefensive, anti-diabetic, aphrodisiac, memory boosting etc. The plant is also effective in combating various types of cancer and other related problems of colon, mammary, lung, prostate, skin, blood, liver and kidney.

AIM OF THIS REVIEW

The present review represents the critical assessment of the literature available on the anticancerous role of W. somnifera. The present study throws light on its diverse chemical compounds and the possible mechanisms of action involved. This review also suggests further research strategies to harness the therapeutic potential of this plant.

MATERIALS AND METHODS

The present review is the outcome of a systematic search of scientific literature about 'Withania somnifera and its role in cancer prevention'. The scientific databases viz. Google Scholar, Science Direct, Pubmed and Web of Science were searched from 2001 to 2019. Textbooks, magazines and newspapers were also consulted. This review summarizes all the published literature about its therapeutic potential for the treatment of different types of cancers.

RESULTS

W. somnifera has been widely used in traditional and ayurvedic medicines for treatment of numerous problems related to health and vitality. The plant is a reservoir of diverse phytoconstituents like alkaloids, steroids, flavonoids, phenolics, nitrogen containing compounds and trace elements. Withanolides are the major alkaloids which renders its anticancer potential due to its highly oxygenated nature. The plant is highly effective in combating various types of cancers viz. colon, mammary, lung, prostate, skin, blood, liver and kidney. Previous studies depict that this plant is more effective against breast cancer followed by colon, lung, prostate and blood cancer. Furthermore, from different clinical studies it has been observed that the active constituents of the plant like withaferin-A, withanolide-D have least toxic effects.

CONCLUSION

The present review confirms the various medicinal values of W. somnifera without any significant side effects. Withaferin-A (WA) and Withanolides are its most promising anticancer compounds that play a major role in apoptosis induction. Keeping in mind the anticancerous potential of this plant, it is suggested that this plant may further be investigated and more clinical studies can be performed.

Keeping abreast about ashwagandha in breast cancer

ETHNOPHARMACOLOGICAL RELEVANCE

Ashwagandha has been used as an ayurvedic medicine in the form of 'Rasayana' (as a tonic) even before 3000 BCE in India. As per Ayurveda, it has long been used traditionally for the treatment of inflammation, weakness, impotence, pulmonary tuberculosis. This plant is also beneficial in lumbago and leucorrhea in the female. In the recent past, Withania has shown its anti-cancerous activity in various experimental models. In addition, Withania also possesses many other properties such as anti-oxidant, anti-stress, adaptogenic, and regenerative which will eventually be beneficial and safe in treating cancer patients.

AIM OF THE STUDY

This review aims to provide experimental evidence along with a deeper insight into molecular mechanisms of Ashwagandha (Withania somnifera (L.) Dunal) through which it acts as a chemotherapeutic agent against different types of breast cancer.

MATERIALS AND METHODS

Literature searches with the help of electronic online databases (Elsevier, Google Scholar, Scopus, Springer Link, ScienceDirect, ResearchGate, PubMed) were carried out. The timeline for collection of data for the review article was from 2000 to 2019. The plant name was validated from The Plant List (2013). Version 1.1. Published on http://www.theplantlist.org/(accessed 21st March 2020).

RESULTS

Various forms of Withania somnifera were used and several in vitro, in vivo, and clinical studies were reported by researchers. They found ashwagandha to exhibit anti-apoptotic, anti-metastatic, anti-invasive and anti-inflammatory properties and gave the evidence that ashwagandha has a capability for averting and treating breast cancer.

CONCLUSION

Various in vitro and in vivo studies suggested Ashwagandha may possess a potential for treating breast cancer, especially ER/PR positive breast cancer and triple-negative breast cancer. A clinical trial has also been conducted in the past that suggested its potential in refining quality of life in breast cancer patients. Studies directed towards molecular pathways have helped in unravelling the key mechanisms of ashwagandha. Future research should be directed towards translational studies involving breast cancer patients. These will reinforce the ancient power of our Ayurvedic medicine.

The Role of Forkhead Box Q1 Transcription Factor in Anticancer Effects of Withaferin A in Breast Cancer

Elimination of both rapidly dividing epithelial mammary cancer cells as well as breast cancer stem-like cells (bCSC) is essential for maximizing antitumor response. Withaferin A (WA), a small molecule derived from a medicinal plant (Withania somnifera), is highly effective in reducing burden and/or incidence of breast cancer in vivo in various preclinical models. We have shown previously that suppression of breast cancer incidence by WA administration in a rat model is associated with a decrease in self-renewal of bCSC but the underlying mechanism is still elusive. This study investigated the role of forkhead box Q1 (FoxQ1) transcription factor in antitumor responses to WA. Exposure of MDA-MB-231 and SUM159 cells to WA resulted in downregulation of protein and mRNA levels of FoxQ1 as well as inhibition of its transcriptional activity. FoxQ1 overexpression in SUM159 and MCF-7 cells resulted in a marked protection against WA-mediated inhibition of bCSC as judged by flow cytometric analysis of CD49f^high population and mammosphere assay. RNA-sequencing analysis revealed upregulation of many bCSC-associated genes by FoxQ1 overexpression in SUM159 cells, including IL8 whose expression was decreased by WA treatment in SUM159 and MCF-7 cells. FoxQ1 was recruited to the promoter of IL8 that was inhibited significantly by WA treatment. On the other hand, WA-mediated inhibition of cell proliferation or migration was not affected by FoxQ1 overexpression. The FoxQ1 overexpression partially attenuated WA-mediated G₂-M phase cell cycle arrest in SUM159 cells only. These results indicate that FoxQ1 is a target of WA for inhibition of bCSC fraction. PREVENTION RELEVANCE: Withaferin A (WA) is highly effective in reducing burden and/or incidence of breast cancer in various preclinical models. However, the mechanism underlying breast cancer prevention by WA is not fully understood. This study shows a role for FoxQ1 in antitumor response to WA.

RNA-seq reveals novel cancer-selective and disease subtype-independent mechanistic targets of withaferin A in human breast cancer cells

Withaferin A (WA) exhibits cancer chemopreventive efficacy in preclinical models representative of two different subtypes of breast cancer. However, the mechanism(s) underlying breast cancer chemoprevention by WA is not fully elucidated. We performed RNA-seq analyses using a non-tumorigenic mammary epithelial cell line (MCF-10A) and human breast cancer cells (BCC) belonging to the luminal-type (MCF-7), HER2-enriched (SK-BR-3), and basal-like subtype (MDA-MB-231) to identify novel cancer-selective mechanistic targets of WA. The WA-regulated transcriptome was strikingly different between MCF-10A versus BCC. The Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed downregulation of genes associated with cellular senescence in WA-treated BCC. Consequently, the number of senescence-associated β-galactosidase positive cells was decreased significantly in WA-treated BCC but not in the MCF-10A cells. WA treatment caused upregulation of senescence marker p21 more robustly in BCC than in MCF-10A. Breast cancer prevention by WA in rats was also associated with upregulation of p21 protein expression. The Reactome pathway analyses indicated upregulation of genes associated with cellular response to stress/external stimuli in WA-treated BCC but not in MCF-10A. Two proteins represented in these pathways (HSPA6 and NRF2) were further investigated. While HSPA6 was dispensable for WA-mediated apoptosis and autophagy or inhibition of cell migration, the NRF2 knockout cells were more resistant to apoptosis resulting from WA treatment than control cells. Finally, expression of some glycolysis-related proteins was decreased by WA treatment both in vitro and in vivo. In summary, this study provides novel insights into cancer-selective pathways affected by WA that may contribute to its chemopreventive efficacy in breast cancer.

A Comprehensive Review and Perspective on Anticancer Mechanisms of Withaferin A in Breast Cancer

Withaferin A (hereafter abbreviated as WA) is a promising anticancer steroidal lactone abundant in a medicinal plant (Withania somnifera) native to Asia. The root/leaf extract of Withania somnifera, which belongs to the Solanaceae family, continues to be included in the Ayurvedic medicine formulations of alternative medicine practice. Numerous chemicals are detectable in the root/leaf extract of Withania somnifera [e.g., withanolides (WA, withanone, withanolide A, etc.), alkaloids, sitoindosides, etc.], but the anticancer effect of this medicinal plant is largely attributed to WA. Anticancer effect of WA was initially reported in the early 70s in the Ehrlich ascites tumor cell model in vitro Since then, numerous preclinical studies have been performed using cellular and animal models of different cancers including breast cancer to determine cancer therapeutic and chemopreventive effects of WA. Chemoprevention, a word first introduced by Dr. Michael B. Sporn, was intended to impede, arrest, or reverse carcinogenesis at its earliest stages with pharmacologic agents. This review succinctly summarizes the published findings on anticancer pharmacology of WA in breast cancer focusing on pharmacokinetic behavior, in vivo efficacy data in preclinical models in a therapeutic and chemoprevention settings, and its known effects on cancer-relevant cellular processes (e.g., growth arrest, apoptosis induction, autophagy, metabolic adaptation, immune function, etc.) and molecular targets (e.g., suppression of oncogenes such as estrogen receptor-α, STAT3, etc.). Potential gaps in knowledge as well as future research directions essential for clinical development of WA for chemoprevention and/or treatment of breast cancer are also discussed.

RNA-seq reveals novel mechanistic targets of withaferin A in prostate cancer cells

Withaferin A (WA) is a promising phytochemical exhibiting in vitro and in vivo anticancer activities against prostate and other cancers, but the mechanism of its action is not fully understood. In this study, we performed RNA-seq analysis using 22Rv1 human prostate cancer cell line to identify mechanistic targets of WA. Kyoto Encyclopedia of Genes and Genomes pathway analysis of the differentially expressed genes showed most significant enrichment of genes associated with metabolism. These results were validated using LNCaP and 22Rv1 human prostate cancer cells and Hi-Myc transgenic mice as models. The intracellular levels of acetyl-CoA, total free fatty acids and neutral lipids were decreased significantly following WA treatment in both cells, which was accompanied by downregulation of mRNA (confirmed by quantitative reverse transcription-polymerase chain reaction) and protein levels of key fatty acid synthesis enzymes, including ATP citrate lyase, acetyl-CoA carboxylase 1, fatty acid synthase and carnitine palmitoyltransferase 1A. Ectopic expression of c-Myc, but not constitutively active Akt, conferred a marked protection against WA-mediated suppression of acetyl-CoA carboxylase 1 and fatty acid synthase protein expression, and clonogenic cell survival. WA was a superior inhibitor of cell proliferation and fatty acid synthesis in comparison with known modulators of fatty acid metabolism including cerulenin and etomoxir. Intraperitoneal WA administration to Hi-Myc transgenic mice (0.1 mg/mouse, three times/week for 5 weeks) also resulted in a significant decrease in circulating levels of total free fatty acids and phospholipids, and expression of ATP citrate lyase, acetyl-CoA carboxylase 1, fatty acid synthase and carnitine palmitoyltransferase 1A proteins in the prostate in vivo.

Mechanisms of Anti-Tumor Activity of Withania somnifera (Ashwagandha)

Increasing herbal formulations have been used to treat several diseases including cancer. W. somnifera (Ashwagandha) is one such plant the extracts of which have been tested against a number of ailments including cancer, which remains as one of the most dreadful diseases on the globe. The ever-increasing number of cancer related mortality demands the development of novel chemopreventive agents with minimum side effects. Different compounds isolated from various parts of the plant like root, stem, and leaves have been reported to display significant anti-cancerous and immunomodulating properties and thus can be used alone or in combination with other chemotherapeutic drugs for cancer treatment. Through this review, we highlight the importance of W. somnifera in countering the potential oncogenic signaling mediators that are modulated by active constituents of W. somnifera in a variety of cancer types. Further, we hope that active constituents of W. somnifera will be tested in clinical trials so that they can be used as an important adjuvant in the near future for the effective treatment of cancer.

Withania somnifera (L.) Dunal: A potential therapeutic adjuvant in cancer

ETHNOPHARMACOLOGICAL RELEVANCE

Withania somnifera (L.) Dunal (WS) is one of the moststudied Rasayana botanicals used in Ayurveda practice for its immunomodulatory, anti-aging, adaptogenic, and rejuvenating effects. The botanical is being used for various clinical indications, including cancer. Several studies exploring molecular mechanisms of WS suggest its possible role in improving clinical outcomes in cancer management. Therefore, research on WS may offer new insights in rational development of therapeutic adjuvants for cancer.

AIM OF THIS REVIEW

The review aims at providing a detailed analysis of in silico, in vitro, in vivo, and clinical studies related to WS and cancer. It suggests possible role of WS in regulating molecular mechanisms associated with carcinogenesis. The review discusses potential of WS in cancer management in terms of cancer prevention, anti-cancer activity, and enhancing efficacy of cancer therapeutics.

MATERIAL AND METHODS

The present narrative review offers a critical analysis of published literature on WS studies in cancer. The reported studies were analysed in the context of pathophysiology of cancer, commonly referred as 'cancer hallmarks'. The review attempts to bridge Ayurveda knowledge with biological insights into molecular mechanisms of cancer.

RESULTS

Critical analysisof the published literature suggests an anti-cancer potential of WS with a key role in cancer prevention. The possible mechanisms for these effects are associated with the modulation of apoptotic, proliferative, and metastatic markers in cancer. WS can attenuate inflammatory responses and enzymes involved in invasion and metastatic progression of cancer.The properties of WS are likely to be mediated through withanolides, which may activate tumor suppressor proteins to restrict proliferation of cancer cells. Withanolides also regulate the genomic instability, and energy metabolism of cancer cells. The reported studies indicate the need for deeper understanding of molecular mechanisms of WS in inhibiting angiogenesis and promoting immunosurveillance. Additionally, WS can augment efficacy and safety of cancer therapeutics.

CONCLUSION

The experimentally-supported evidence of immunomodulatory, anti-cancer, adaptogenic, and regenerative attributes of WS suggest its therapeutic adjuvant potential in cancer management. The adjuvant properties of withanolides can modulate multidrug resistance and reverse chemotherapy-induced myelosuppression. These mechanisms need to be further explored in systematically designed translational and clinical studies that will pave the way for integration of WS as a therapeutic adjuvant in cancer management.

The Role of Lysosome-associated Membrane Protein 2 in Prostate Cancer Chemopreventive Mechanisms of Sulforaphane

Prostate cancer chemoprevention by sulforaphane, which is a metabolic by-product of glucoraphanin found in broccoli, in preclinical models is associated with induction of both apoptosis and autophagy. However, the molecular mechanism underlying sulforaphane-mediated autophagy, which is protective against apoptotic cell death by this phytochemical, is still poorly understood. This study demonstrates a role for lysosome-associated membrane protein 2 (LAMP2) in sulforaphane-mediated autophagy and apoptosis. Western blotting revealed dose-dependent induction of LAMP2 protein after treatment with sulforaphane as well as its naturally occurring analogs in PC-3 and 22Rv1 human prostate cancer cell lines that was confirmed by microscopy (sulforaphane). The mRNA level of LAMP2 was also increased upon treatment with sulforaphane in both cell lines. Sulforaphane-mediated increase in the level of autophagy marker microtubule-associated protein light-chain 3B was augmented by RNAi of LAMP2 in PC-3 and 22Rv1 cells. Apoptosis induction by sulforaphane treatment was also increased significantly by knockdown of the LAMP2 protein in PC-3 and 22Rv1 cells. Augmentation of sulforaphane-mediated apoptosis by RNAi of LAMP2 was accompanied by induction and activation of proapoptotic protein Bak. Oral administration of sulforaphane to TRAMP mice also resulted in induction of LAMP2 protein expression. Targeted microarray in sulforaphane-treated PC-3 cells revealed induction of many autophagy-related genes (e.g., HSP90AA1, NRF2, etc) and their expression positively correlated with that of LAMP2 in prostate cancer The Cancer Genome Atlas. In conclusion, this study reveals that induction of LAMP2 by sulforaphane inhibits its ability to induce apoptotic cell death at least in human prostate cancer cells.

Pharmacological evaluation of Ashwagandha highlighting its healthcare claims, safety, and toxicity aspects

Withania somnifera, commonly known as "Ashwagandha" or "Indian ginseng" is an essential therapeutic plant of Indian subcontinent regions. It is regularly used, alone or in combination with other plants for the treatment of various illnesses in Indian Systems of Medicine over the period of 3,000 years. Ashwagandha (W. somnifera) belongs to the genus Withania and family Solanaceae. It comprises a broad spectrum of phytochemicals having wide range of biological effects. W. somnifera has demonstrated various biological actions such as anti-cancer, anti-inflammatory, anti-diabetic, anti-microbial, anti-arthritic, anti-stress/adaptogenic, neuro-protective, cardio-protective, hepato-protective, immunomodulatory properties. Furthermore, W. somnifera has revealed the capability to decrease reactive oxygen species and inflammation, modulation of mitochondrial function, apoptosis regulation and improve endothelial function. Withaferin-A is an important phytoconstituents of W. somnifera belonging to the category of withanolides been used in the traditional system of medicine for the treatment of various disorders. In this review, we have summarized the active phytoconstituents, pharmacologic activities (preclinical and clinical), mechanisms of action, potential beneficial applications, marketed formulations and safety and toxicity profile of W. somnifera.

A Novel Sulforaphane-Regulated Gene Network in Suppression of Breast Cancer-Induced Osteolytic Bone Resorption

Bone is the most preferred site for colonization of metastatic breast cancer cells for each subtype of the disease. The standard of therapeutic care for breast cancer patients with bone metastasis includes bisphosphonates (e.g., zoledronic acid), which have poor oral bioavailability, and a humanized antibody (denosumab). However, these therapies are palliative, and a subset of patients still develop new bone lesions and/or experience serious adverse effects. Therefore, a safe and orally bioavailable intervention for therapy of osteolytic bone resorption is still a clinically unmet need. This study demonstrates suppression of breast cancer-induced bone resorption by a small molecule (sulforaphane, SFN) that is safe clinically and orally bioavailable. In vitro osteoclast differentiation was inhibited in a dose-dependent manner upon addition of conditioned media from SFN-treated breast cancer cells representative of different subtypes. Targeted microarrays coupled with interrogation of The Cancer Genome Atlas data set revealed a novel SFN-regulated gene signature involving cross-regulation of runt-related transcription factor 2 (RUNX2) and nuclear factor-κB and their downstream effectors. Both RUNX2 and p65/p50 expression were higher in human breast cancer tissues compared with normal mammary tissues. RUNX2 was recruited at the promotor of NFKB1 Inhibition of osteoclast differentiation by SFN was augmented by doxycycline-inducible stable knockdown of RUNX2. Oral SFN administration significantly increased the percentage of bone volume/total volume of affected bones in the intracardiac MDA-MB-231-Luc model indicating in vivo suppression of osteolytic bone resorption by SFN. These results indicate that SFN is a novel inhibitor of breast cancer-induced osteolytic bone resorption in vitro and in vivo.

Withaferin A triggers G2/M arrest and intrinsic apoptosis in glioblastoma cells via ATF4-ATF3-CHOP axis

OBJECTIVE

Withaferin A (WA) is a bioactive compound with a remarkable anti-cancer effect derived from Withania somnifera, commonly known as ashwagandha. However, the anti-cancer mechanisms of WA in glioblastoma multiforme (GBM) are still unclear.

MATERIALS AND METHODS

Cell viability assays and xenografted nude mice were used to evaluate the effects of WA, along with flow cytometry to detect apoptosis and cell cycle of GBM. RNA-seq analysis, Western blotting, immunofluorescence staining, qRT-PCR and siRNA gene silencing were carried out to determine the signalling pathways affected by WA.

RESULTS

Withaferin A significantly inhibited the growth of GBM in vitro and in vivo and triggered the intrinsic apoptosis of GBM cells by up-regulating expression of Bim and Bad. WA arrested GBM cells at the G2/M phase of the cell cycle through dephosphorylating Thr161 of CDK1 by activating p53-independent p21 up-regulation. Knockdown of p21 restored cell cycle progression and cell viability by down-regulating the expression of Bad rather than Bim. We demonstrated that endoplasmic reticulum (ER) stress induced by WA through the ATF4-ATF3-CHOP axis, initiated apoptosis and G2/M arrest in GBM cells.

CONCLUSION

We revealed a novel pathway that elucidated WA activation of apoptosis and G2/M arrest in GBM cells through the ATF4-ATF3-CHOP axis. This discovery is important for optimization of WA-based regimens for prevention and/or treatment of GBM.

Bioactive Compounds: Multi-Targeting Silver Bullets for Preventing and Treating Breast Cancer

Each cell in our body is designed with a self-destructive trigger, and if damaged, can happily sacrifice itself for the sake of the body. This process of self-destruction to safeguard the adjacent normal cells is known as programmed cell death or apoptosis. Cancer cells outsmart normal cells and evade apoptosis and it is one of the major hallmarks of cancer. The cardinal quest for anti-cancer drug discovery (bioactive or synthetic compounds) is to be able to re-induce the so called “programmed cell death” in cancer cells. The importance of bioactive compounds as the linchpin of cancer therapeutics is well known as many effective chemotherapeutic drugs such as vincristine, vinblastine, doxorubicin, etoposide and paclitaxel have natural product origins. The present review discusses various bioactive compounds with known anticancer potential, underlying mechanisms by which they induce cell death and their preclinical/clinical development. Most bioactive compounds can concurrently target multiple signaling pathways that are important for cancer cell survival while sparing normal cells hence they can potentially be the silver bullets for targeting cancer growth and metastatic progression.

Withaferin A inhibits lysosomal activity to block autophagic flux and induces apoptosis via energetic impairment in breast cancer cells

Withaferin A (WFA), a steroidal lactone, negatively regulates breast cancer growth however, its mechanisms of action remain largely elusive. We found that WFA blocks autophagy flux and lysosomal proteolytic activity in breast cancer cells. WFA increases accumulation of autophagosomes, LC3B-II conversion, expression of autophagy-related proteins and autophagosome/lysosome fusion. Autolysosomes display the characteristics of acidic compartments in WFA-treated cells; however, the protein degradation activity of lysosomes is inhibited. Blockade of autophagic flux reduces the recycling of cellular fuels leading to insufficient substrates for tricarboxylic acid (TCA) cycle and impaired oxidative phosphorylation. WFA decreases expression and phosphorylation of lactate dehydrogenase, the key enzyme that catalyzes pyruvate-to-lactate conversion, reduces adenosine triphosphate levels and increases AMP-activated protein kinase (AMPK) activation. AMPK inhibition abrogates while AMPK activation potentiates WFA's effect. WFA and 2-deoxy-d-glucose combination elicits synergistic inhibition of breast cancer cells. Genetic knockout of BECN1 and ATG7 fails to rescue cells from WFA treatment; in contrast, addition of methyl pyruvate to supplement TCA cycle protects WFA-treated cells. Together, these results implicate that WFA is a potent lysosomal inhibitor; energetic impairment is required for WFA-induced apoptosis and growth inhibition and combining WFA and 2-DG is a promising therapeutic strategy for breast cancer.

Withaferin A inhibits expression of ataxia telangiectasia and Rad3-related kinase and enhances sensitivity of human breast cancer cells to cisplatin

Ataxia telangiectasia and Rad3-related (ATR) is a serine/threonine-specific kinase that plays an important role in the maintenance of genomic integrity. In this study, we investigated the role of ATR in cell-cycle arrest by withaferin A (WA), a cancer preventative steroidal lactone derived from Withania somnifera plant abundant in India and surrounding countries. The WA treatment decreased the viability of MCF-7, MDA-MB-231, and SUM159 cells. Exposure of breast cancer cells to WA also resulted in suppression of protein level as well as phosphorylation of ATR and its downstream effector kinase (checkpoint kinase 1; CHK1). Both transcriptional and posttranscriptional mechanisms were involved in the WA-mediated downregulation of ATR protein. Downregulation of ATR protein expression resulting from WA exposure was not attenuated by overexpression of manganese superoxide dismutase. In contrast, the overexpression of CHK1 attenuated WA-mediated G₂ /M arrest and augmented S10 phosphorylation of histone H3, a marker of mitotic arrest. The protein level of ATR was lowered by about 50% in breast tumors of WA-treated mouse mammary tumor virus-neu mice when compared with vehicle-treated controls but the difference was not significant due to small sample size. WA treatment sensitized MDA-MB-231 and SUM159 cells to growth inhibition and apoptosis induction by cisplatin. Cisplatin treatment resulted in increased autophosphorylation of ATR (T1989) and CHK1 (S345) phosphorylation that was markedly suppressed in the presence of WA. These results indicate that WA is an inhibitor of ATR in human breast cancer cells.

Leelamine Is a Novel Lipogenesis Inhibitor in Prostate Cancer Cells In Vitro and In Vivo

Increased de novo synthesis of fatty acids is implicated in the pathogenesis of human prostate cancer, but a safe and effective clinical inhibitor of this metabolic pathway is still lacking. We have shown previously that leelamine (LLM) suppresses transcriptional activity of androgen receptor, which is known to regulate fatty acid synthesis. Therefore, the current study was designed to investigate the effect of LLM on fatty acid synthesis. Exposure of 22Rv1, LNCaP, and PC-3 prostate cancer cells, but not RWPE-1 normal prostate epithelial cell line, to LLM resulted in a decrease in intracellular levels of neutral lipids or total free fatty acids. LLM was superior to another fatty acid synthesis inhibitor (cerulenin) for suppression of total free fatty acid levels. LLM treatment downregulated protein and/or mRNA expression of key fatty acid synthesis enzymes, including ATP citrate lyase, acetyl-CoA carboxylase 1, fatty acid synthase, and sterol regulatory element-binding protein 1 (SREBP1) in each cell line. Consistent with these in vitro findings, we also observed a significant decrease in ATP citrate lyase and SREBP1 protein expression as well as number of neutral lipid droplets in vivo in 22Rv1 tumor sections of LLM-treated mice when compared with that of controls. LLM-mediated suppression of intracellular levels of total free fatty acids and neutral lipids was partly attenuated by overexpression of SREBP1. In conclusion, these results indicate that LLM is a novel inhibitor of SREBP1-regulated fatty acid/lipid synthesis in prostate cancer cells that is not affected by androgen receptor status.

Withaferin A-mediated apoptosis in breast cancer cells is associated with alterations in mitochondrial dynamics

Withaferin A (WA), a steroidal lactone derived from a medicinal plant (Withania somnifera), inhibits cancer development in transgenic and chemically-induced rodent models of breast cancer but the underlying mechanism is not fully grasped. We have shown previously that WA treatment causes apoptotic cell death in human breast cancer cells that is preceded by inhibition of complex III of the mitochondrial electron transport chain. This study extends these observations to now demonstrate alterations in mitochondrial dynamics in WA-induced apoptosis. Assembly of complex III was decreased in MCF-7 and SUM159 cells but not in MDA-MB-231 as determined by native blue gel electrophoresis. Because WA is a Michael acceptor (electrophile), we explored the possibility of whether it covalently modifies cysteine residue(s) in ubiquinol-cytochrome c reductase, Rieske iron-sulfur polypeptide 1 (UQCRFS1). Covalent modification of cysteine in UQCRFS1 was not observed after WA treatment. Instead, WA treatment inhibited chemically-induced mitochondrial fusion and decreased the mitochondrial volume, and this effect was accompanied by a decrease in the expression of proteins involved in fusion process, including mitofusin1, mitofusin2, and full-length optic atrophy protein 1 (OPA1). A loss of volume in fragmented mitochondria also occurred in WA-exposed cells when compared to vehicle-treated control. WA treatment also caused a decrease in protein level of mitochondrial fission-regulating protein dynamin-related protein 1 (DRP1). Functional studies revealed that DRP1 deficiency and OPA1 knockdown attenuated apoptotic potential of WA. Taken together, these results indicate that WA not only alters Complex III assembly but also inhibits mitochondrial dynamics in breast cancer cells.

Withaferin A Prevents Myocardial Ischemia/Reperfusion Injury by Upregulating AMP-Activated Protein Kinase-Dependent B-Cell Lymphoma2 Signaling

BACKGROUND

Withaferin A (WFA), an anticancer constituent of the plant Withania somnifera, inhibits tumor growth in association with apoptosis induction. However, the potential role of WFA in the cardiovascular system is little-studied and controversial.Methods and Results:Two different doses of WFA were tested to determine their cardioprotective effects in myocardial ischemia/reperfusion (MI/R) injury through evaluation of cardiofunction in wild-type and AMP-activated protein kinase domain negative (AMPK-DN) gentransgenic mice. Surprisingly, cardioprotective effects (improved cardiac function and reduced infarct size) were observed with low-dose WFA (1 mg/kg) delivery but not high-dose (5 mg/kg). Mechanistically, low-dose WFA attenuated myocardial apoptosis. It decreased MI/R-induced activation of caspase 9, the indicator of the intrinsic mitochondrial pathway, but not caspase 8. It also upregulated the level of AMP-activated protein kinase (AMPK) phosphorylation and increased the MI/R inhibited ratio of Bcl2/Bax. In AMPK-deficient mice, WFA did not ameliorate MI/R-induced cardiac dysfunction, attenuate infarct size, or restore the Bcl2/Bax (B-cell lymphoma2/Mcl-2-like protein 4) ratio.

CONCLUSIONS

These results demonstrated for the first time that low-dose WFA is cardioprotective via upregulation of the anti-apoptotic mitochondrial pathway in an AMPK-dependent manner.

The chemopreventive effect of withaferin A on spontaneous and inflammation-associated colon carcinogenesis models

Chemopreventive effects and associated mechanisms of withaferin A (WA) against intestinal and colon carcinogenesis remain unknown. We investigated the chemopreventive effect of WA on transgenic adenomatous polyposis coli (APCMin/+) mouse and chemically induced azoxymethane/dextran sodium sulfate (AOM/DSS) models of intestinal and colon carcinogenesis. Oral WA administration (4 and 3 mg/kg) inhibited tumor initiation and progression of intestinal polyps formation in APCMin/+ mice and colon carcinogenesis in the AOM/DSS mouse model. WA-administered mice showed a significant reduction in both number [duodenum, 33% (P > 0.05); jejunum, 32% (P < 0.025); ileum, 43% ( P < 0.001); and colon 59% (P < 0.01] and size of polyps in APCMin/+ mice compared with the respective controls. Similarly, tumor multiplicity was significantly reduced (P < 0.05) in the colon of WA-administered AOM/DSS mice. Pathological analysis showed reduced adenomas and tissue inflammation in WA-administered mouse models. Molecular studies suggested that WA inhibited the expression of inflammatory (interluekin-6, tumor necrosis factor-alpha and cyclooxygenase-2), pro-survival (pAKT, Notch1 and NF-κB) markers in APCMin/+ and AOM/DSS models. The results suggest that WA is a potent agent for preventing colon carcinogenesis and further investigation is required to show clinical utility of the agent.

AKT-dependent sugar addiction by benzyl isothiocyanate in breast cancer cells

The overall promise of breast cancer chemoprevention is exemplified by clinical success of selective estrogen receptor modulators and aromatase inhibitors. Despite clinical efficacy, these interventions have limitations, including rare but serious side effects and lack of activity against estrogen receptor-negative breast cancers. We have shown previously that dietary administration of benzyl isothiocyanate (BITC), which occurs naturally as a thioglucoside conjugate in edible cruciferous vegetables, inhibits development of estrogen receptor-negative breast cancer in mouse mammary tumor virus-neu (MMTV-neu) transgenic mice. This study demonstrates AKT-mediated sugar addiction in breast cancer chemoprevention by BITC. BITC-treated MMTV-neu mice exhibited increased 2-deoxy-2-(¹⁸ F)-fluoro-D-glucose (¹⁸ F-FDG) uptake in mammary tumors in vivo in comparison with mice fed basal diet. Cellular studies using MDA-MB-231 and SUM159 human breast cancer cell lines revealed BITC-mediated induction and punctate localization of glucose transporter GLUT-1, which was accompanied by an increase in intracellular pyruvate levels. BITC treatment resulted in increased S⁴⁷³ phosphorylation (activation) of AKT in cells in vitro as well as in mammary tumors of MMTV-neu mice in vivo. Increased glucose uptake, punctate pattern of GLUT-1 localization, and intracellular pyruvate levels resulting from BITC exposure were significantly attenuated in the presence of a pharmacological inhibitor of AKT (MK-2206). Inhibition of AKT augmented BITC-mediated inhibition of cell migration and colony formation. BITC-induced apoptotic cell death was also increased by pharmacological inhibition of AKT. These results indicate increased glucose uptake/metabolism by BITC treatment in breast cancer cells suggesting that breast cancer chemoprevention by BITC may be augmented by pharmacological inhibition of AKT.

Role of Krüppel-like Factor 4-p21CIP1 Axis in Breast Cancer Stem-like Cell Inhibition by Benzyl Isothiocyanate

Cancer chemoprevention by benzyl isothiocyanate (BITC), which is derived from cruciferous vegetables like garden cress, in a transgenic mouse model of breast cancer is associated with inhibition of breast cancer stem-like cells (bCSC), but the molecular regulators of this effect remain elusive. This study demonstrates a protective effect of Krüppel-like factor 4 (KLF4)-p21^CIP1 axis in bCSC inhibition by BITC. Exposure of human breast cancer cells (MCF-7, MDA-MB-231, and SUM159) to plasma-achievable concentrations of BITC resulted in a robust induction of KLF4 mRNA and its protein expression as determined by qRT-PCR and Western blotting or confocal microscopy. BITC-mediated suppression of bCSC markers, including aldehyde dehydrogenase 1 activity and mammosphere frequency, was significantly augmented by transient or stable knockdown of KLF4. Western blotting and IHC revealed relatively higher levels of KLF4 protein in mammary tumor sections from BITC-treated mice in comparison with controls, but the difference was insignificant. Analysis of the breast cancer RNA-Seq data from The Cancer Genome Atlas indicated significant positive correlation between expression of KLF4 and that of p21^CIP1 (CDKN1A) but not β-Catenin (CTNNB1). Knockdown of p21^CIP1 protein also amplified BITC-mediated suppression of bCSC. Finally, KLF4 was recruited to the promoter of p21^CIP1 as indicated by chromatin immunoprecipitation assay. These results indicate that induction of KLF4-p21^CIP1 axis attenuates inhibitory effect of BITC on bCSC self-renewal. Translational implication of these findings is that breast cancer chemoprevention by BITC may be augmented with a combination regimen involving BITC and an inhibitor of KLF4.

Adenylate kinase 4 modulates oxidative stress and stabilizes HIF-1α to drive lung adenocarcinoma metastasis

Background

Adenylate kinase 4 (AK4) has been identified as a biomarker of metastasis in lung cancer. However, the impacts of AK4 on metabolic genes and its translational value for drug repositioning remain unclear.

Methods

Ingenuity upstream analyses were used to identify potential transcription factors that regulate the AK4 metabolic gene signature. The expression of AK4 and its upstream regulators in lung cancer patients was examined via immunohistochemistry. Pharmacological and gene knockdown/overexpression approaches were used to investigate the interplay between AK4 and its upstream regulators during epithelial-to-mesenchymal transition (EMT). Drug candidates that reversed AK4-induced gene expression were identified by querying a connectivity map. Orthotopic xenograft mouse models were established to evaluate the therapeutic efficacy of drug candidates for metastatic lung cancer.

Results

We found that HIF-1α is activated in the AK4 metabolic gene signature. IHC analysis confirmed this positive correlation, and the combination of both predicts worse survival in lung cancer patients. Overexpression of AK4 exaggerates HIF-1α protein expression by increasing intracellular ROS levels and subsequently induces EMT under hypoxia. Attenuation of ROS production with N-acetylcysteine abolishes AK4-induced invasion potential under hypoxia. Pharmacogenomics analysis of the AK4 gene signature revealed that withaferin-A could suppress the AK4-HIF-1α signaling axis and serve as a potent anti-metastatic agent in lung cancer.

Conclusions

Overexpression of AK4 promotes lung cancer metastasis by enhancing HIF-1α stability and EMT under hypoxia. Reversing the AK4 gene signature with withaferin-A may serve as a novel therapeutic strategy to treat metastatic lung cancer.

Electronic supplementary material

The online version of this article (10.1186/s13045-019-0698-5) contains supplementary material, which is available to authorized users.

Prostate cancer chemoprevention by sulforaphane in a preclinical mouse model is associated with inhibition of fatty acid metabolism

Increased de novo synthesis of fatty acids is a rather unique and targetable mechanism of human prostate cancer. We have shown previously that oral administration of sulforaphane (SFN) significantly inhibits the incidence and/or burden of prostatic intraepithelial neoplasia and well-differentiated adenocarcinoma in TRansgenic Adenocarcinoma of Mouse Prostate (TRAMP) mice. The present study used cellular models of prostate cancer and archived plasma/adenocarcinoma tissues and sections from the TRAMP study to demonstrate inhibition of fatty acid synthesis by SFN treatment in vitro and in vivo. Treatment of androgen-responsive (LNCaP) and castration-resistant (22Rv1) human prostate cancer cells with SFN (5 and 10 μM) resulted in downregulation of protein and mRNA levels of acetyl-CoA carboxylase 1 (ACC1) and fatty acid synthase (FASN), but not ATP citrate lyase. Protein and mRNA levels of carnitine palmitoyltransferase 1A (CPT1A), which facilitates fatty acid uptake by mitochondria for β-oxidation, were also decreased following SFN treatment in both cell lines. Immunohistochemistry revealed a significant decrease in expression of FASN and ACC1 proteins in prostate adenocarcinoma sections of SFN-treated TRAMP mice when compared with controls. SFN administration to TRAMP mice resulted in a significant decrease in plasma and/or prostate adenocarcinoma levels of total free fatty acids, total phospholipids, acetyl-CoA and ATP. Consistent with these results, number of neutral lipid droplets was lower in the prostate adenocarcinoma sections of SFN-treated TRAMP mice than in control tumors. Collectively, these observations indicate that prostate cancer chemoprevention by SFN in TRAMP mice is associated with inhibition of fatty acid metabolism.

Prevention of breast cancer-induced osteolytic bone resorption by benzyl isothiocyanate

Osteolytic bone resorption is the primary cause of pain and suffering (e.g. pathological bone fracture) in women with metastatic breast cancer. The current standard of care for patients with bone metastasis for reducing the incidence of skeletal complications includes bisphosphonates and a humanized antibody (denosumab). However, a subset of patients on these therapies still develops new bone metastasis or experiences adverse effects. Moreover, some bisphosphonates have poor oral bioavailability. Therefore, orally-bioavailable and non-toxic inhibitors of breast cancer-induced osteolytic bone resorption are still clinically desirable. We have shown previously that benzyl isothiocyanate (BITC) decreases the incidence of breast cancer in a transgenic mouse model without any side effects. The present study provides in vivo evidence for inhibition of breast cancer-induced osteolytic bone resorption by BITC. Plasma achievable doses of BITC (0.5 and 1 μM) inhibited in vitro osteoclast differentiation induced by co-culture of osteoclast precursor cells (RAW264.7) and breast cancer cells representative of different subtypes. This effect was accompanied by downregulation of key mediators of osteoclast differentiation, including receptor activator of nuclear factor-κB ligand and runt-related transcription factor 2 (RUNX2), in BITC-treated breast cancer cells. Doxycycline-inducible knockdown of RUNX2 augmented BITC-mediated inhibition of osteoclast differentiation. Oral administration of 10 mg BITC/kg body weight, 5 times per week, inhibited MDA-MB-231-induced skeletal metastasis multiplicity by ~81% when compared with control (P = 0.04). The present study indicates that BITC has the ability to inhibit breast cancer-induced osteolytic bone resorption in vivo.

Oxidative stress-modulating drugs have preferential anticancer effects - involving the regulation of apoptosis, DNA damage, endoplasmic reticulum stress, autophagy, metabolism, and migration

To achieve preferential effects against cancer cells but less damage to normal cells is one of the main challenges of cancer research. In this review, we explore the roles and relationships of oxidative stress-mediated apoptosis, DNA damage, ER stress, autophagy, metabolism, and migration of ROS-modulating anticancer drugs. Understanding preferential anticancer effects in more detail will improve chemotherapeutic approaches that are based on ROS-modulating drugs in cancer treatments.

Therapeutic Potential of Leelamine, a Novel Inhibitor of Androgen Receptor and Castration-Resistant Prostate Cancer

Clinical management of castration-resistant prostate cancer (CRPC) resulting from androgen deprivation therapy remains challenging. CRPC is driven by aberrant activation of androgen receptor (AR) through mechanisms ranging from its amplification, mutation, post-translational modification, and expression of splice variants (e.g., AR-V7). Herein, we present experimental evidence for therapeutic vulnerability of CRPC to a novel phytochemical, leelamine (LLM), derived from pine tree bark. Exposure of human prostate cancer cell lines LNCaP (an androgen-responsive cell line with mutant AR), C4-2B (an androgen-insensitive variant of LNCaP), and 22Rv1 (a CRPC cell line with expression of AR-Vs), and a murine prostate cancer cell line Myc-CaP to plasma achievable concentrations of LLM resulted in ligand-dependent (LNCaP) and ligand-independent (22Rv1) growth inhibition in vitro that was accompanied by downregulation of mRNA and/or protein levels of full-length AR as well as its splice variants, including AR-V7. LLM treatment resulted in apoptosis induction in the absence and presence of R1881. In silico modeling followed by luciferase reporter assay revealed a critical role for noncovalent interaction of LLM with Y739 in AR activity inhibition. Substitution of the amine group with an isothiocyanate functional moiety abolished AR and cell viability inhibition by LLM. Administration of LLM resulted in 22Rv1 xenograft growth suppression that was statistically insignificant but was associated with a significant decrease in Ki-67 expression, mitotic activity, expression of full-length AR and AR-V7 proteins, and secretion of PSA. This study identifies a novel chemical scaffold for the treatment of CRPC. Mol Cancer Ther; 17(10); 2079-90. ©2018 AACR.

Evaluation of Biodistribution of Sulforaphane after Administration of Oral Broccoli Sprout Extract in Melanoma Patients with Multiple Atypical Nevi

Broccoli sprout extract containing sulforaphane (BSE-SFN) has been shown to inhibit ultraviolet radiation-induced damage and tumor progression in skin. This study evaluated the toxicity and potential effects of oral BSE-SFN at three dosages. Seventeen patients who each had at least 2 atypical nevi and a prior history of melanoma were randomly allocated to 50, 100, or 200 μmol oral BSE-SFN daily for 28 days. Atypical nevi were photographed on days 1 and 28, and plasma and nevus samples were taken on days 1, 2, and 28. Endpoints assessed were safety, plasma and skin sulforaphane levels, gross and histologic changes, IHC for phospho-STAT3(Y705), Ki-67, Bcl-2, HMOX1, and TUNEL, plasma cytokine levels, and tissue proteomics. All 17 patients completed 28 days with no dose-limiting toxicities. Plasma sulforaphane levels pooled for days 1, 2, and 28 showed median postadministration increases of 120 ng/mL for 50 μmol, 206 ng/mL for 100 μmol, and 655 ng/mL for 200 μmol. Median skin sulforaphane levels on day 28 were 0.0, 3.1, and 34.1 ng/g for 50, 100, and 200 μmol, respectively. Plasma levels of proinflammatory cytokines decreased from day 1 to 28. The tumor suppressor decorin was increased from day 1 to 28. Oral BSE-SFN is well tolerated at daily doses up to 200 μmol and achieves dose-dependent levels in plasma and skin. A larger efficacy evaluation of 200 μmol daily for longer intervals is now reasonable to better characterize clinical and biological effects of BSE-SFN as chemoprevention for melanoma. Cancer Prev Res; 11(7); 429-38. ©2018 AACR.

Peptidyl-prolyl cis/trans isomerase Pin1 regulates withaferin A-mediated cell cycle arrest in human breast cancer cells

We have reported previously that withaferin A (WA) prevents breast cancer development in mouse mammary tumor virus-neu (MMTV-neu) transgenic mice, but the mechanism is not fully understood. Unbiased proteomics of the mammary tumors from control- and WA-treated MMTV-neu mice revealed downregulation of peptidyl-prolyl cis/trans isomerase (Pin1) protein by WA administration. The present study extends these findings to elucidate the role of Pin1 in cancer chemopreventive mechanisms of WA. The mammary tumor level of Pin1 protein was lower by about 55% in WA-treated rats exposed to N-methyl-N-nitrosourea, compared to control. Exposure of MCF-7 and SK-BR-3 human breast cancer cells to WA resulted in downregulation of Pin1 protein. Ectopic expression of Pin1 attenuated G₂ and/or mitotic arrest resulting from WA treatment in both MCF-7 and SK-BR-3 cells. WA-induced apoptosis was increased by Pin1 overexpression in MCF-7 cells but not in the SK-BR-3 cell line. In addition, molecular docking followed by mass spectrometry indicated covalent interaction of WA with cysteine 113 of Pin1. Overexpression of Pin1^C113A mutant failed to attenuate WA-induced mitotic arrest or apoptosis in the MCF-7 cells. Furthermore, antibody array revealed upregulation of proapoptotic insulin-like growth factor binding proteins (IGFBPs), including IGFBP-3, IGFBP-4, IGFBP-5, and IGFBP-6, in Pin1 overexpressing MCF-7 cells following WA treatment when compared to empty vector transfected control cells. These data support a crucial role of the Pin1 for mitotic arrest and apoptosis signaling by WA at least in the MCF-7 cells.

Proteomic characterization of Withaferin A-targeted protein networks for the treatment of monoclonal myeloma gammopathies

Withaferin A (WA), a natural steroid lactone from the plant Withania somnifera, is often studied because of its antitumor properties. Although many in vitro and in vivo studies have been performed, the identification of Withaferin A protein targets and its mechanism of antitumor action remain incomplete. We used quantitative chemoproteomics and differential protein expression analysis to characterize the WA antitumor effects on a multiple myeloma cell model. Identified relevant targets were further validated by Ingenuity Pathway Analysis and Western blot and indicate that WA targets protein networks that are specific for monoclonal gammopathy of undetermined significance (MGUS) and other closely related disorders, such as multiple myeloma (MM) and Waldenström macroglobulinemia (WM). By blocking the PSMB10 proteasome subunit, downregulation of ANXA4, potential association with HDAC6 and upregulation of HMOX1, WA puts a massive blockage on both proteotoxic and oxidative stress responses pathways, leaving cancer cells defenseless against WA induced stresses. These results indicate that WA mediated apoptosis is preceded by simultaneous targeting of cellular stress response pathways like proteasome degradation, autophagy and unfolded protein stress response and thus suggests that WA can be used as an effective treatment for MGUS and other closely related disorders.

SIGNIFICANCE

Multifunctional antitumor compounds are of great potential since they reduce the risk of multidrug resistance in chemotherapy. Unfortunately, characterization of all protein targets of a multifunctional compound is lacking. Therefore, we optimized an SILAC quantitative chemoproteomics workflow to identify the potential protein targets of Withaferin A (WA), a natural multifunctional compound with promising antitumor properties. To further understand the antitumor mechanisms of WA, we performed a differential protein expression analysis and combined the altered expression data with chemoproteome WA target data in the highly curated Ingenuity Pathway database. We provide a first global overview on how WA kills multiple myeloma cancer cells and serve as a starting point for further in depth experiments. Furthermore, the combined approach can be used for other types of cancer and/or other promising multifunctional compounds, thereby increasing the potential development of new antitumor therapies.

Towards natural mimetics of metformin and rapamycin

Aging is now at the forefront of major challenges faced globally, creating an immediate need for safe, widescale interventions to reduce the burden of chronic disease and extend human healthspan. Metformin and rapamycin are two FDA-approved mTOR inhibitors proposed for this purpose, exhibiting significant anti-cancer and anti-aging properties beyond their current clinical applications. However, each faces issues with approval for off-label, prophylactic use due to adverse effects. Here, we initiate an effort to identify nutraceuticals-safer, naturally-occurring compounds-that mimic the anti-aging effects of metformin and rapamycin without adverse effects. We applied several bioinformatic approaches and deep learning methods to the Library of Integrated Network-based Cellular Signatures (LINCS) dataset to map the gene- and pathway-level signatures of metformin and rapamycin and screen for matches among over 800 natural compounds. We then predicted the safety of each compound with an ensemble of deep neural network classifiers. The analysis revealed many novel candidate metformin and rapamycin mimetics, including allantoin and ginsenoside (metformin), epigallocatechin gallate and isoliquiritigenin (rapamycin), and withaferin A (both). Four relatively unexplored compounds also scored well with rapamycin. This work revealed promising candidates for future experimental validation while demonstrating the applications of powerful screening methods for this and similar endeavors.

2,3-Dihydro-3β-methoxy Withaferin-A Protects Normal Cells against Stress: Molecular Evidence of Its Potent Cytoprotective Activity

2,3-Dihydro-3β-methoxy withaferin-A (3βmWi-A) is a natural withanolide that is structurally close to withaferin-A (Wi-A), is cytotoxic to human cancer cells, and is a candidate anticancer natural compound. Using cell-based biochemical, molecular, and imaging assays, we report that Wi-A and 3βmWi-A possess contrasting activities. Whereas Wi-A caused oxidative stress to normal cells, 3βmWi-A was well tolerated at even 10-fold higher concentrations. Furthermore, it promoted survival and protected normal cells against oxidative, UV radiation, and chemical stresses. We provide molecular evidence that 3βmWi-A induces antistress and pro-survival signaling through activation of the pAkt/MAPK pathway. We demonstrate that 3βmWi-A (i) contrary to Wi-A is safe and possesses stress-relieving activity, (ii) when given subsequent to a variety of stress factors including Wi-A, protects normal cells against their toxicity, and (iii) is a vital compound that may guard normal cells against the toxicity associated with various targeted therapeutic regimes in clinical practice.

Molecular docking, QSAR and ADMET studies of withanolide analogs against breast cancer

Withanolides are a group of pharmacologically active compounds present in most prodigal amounts in roots and leaves of Withania somnifera (Indian ginseng), one of the most important medicinal plants of Indian traditional practice of medicine. Withanolides are steroidal lactones (highly oxygenated C-28 phytochemicals) and have been reported to exhibit immunomodulatory, anticancer and other activities. In the present study, a quantitative structure activity relationship (QSAR) model was developed by a forward stepwise multiple linear regression method to predict the activity of withanolide analogs against human breast cancer. The most effective QSAR model for anticancer activity against the SK-Br-3 cell showed the best correlation with activity (r²=0.93 and rCV² =0.90). Similarly, cross-validation regression coefficient (rCV²=0.85) of the best QSAR model against the MCF7/BUS cells showed a high correlation (r²=0.91). In particular, compounds CID_73621, CID_435144, CID_301751 and CID_3372729 have a marked antiproliferative activity against the MCF7/BUS cells, while 2,3-dihydrowithaferin A-3-beta-O-sulfate, withanolide 5, withanolide A, withaferin A, CID_10413139, CID_11294368, CID_53477765, CID_135887, CID_301751 and CID_3372729 have a high activity against the Sk-Br-3 cells compared to standard drugs 5-fluorouracil (5-FU) and camptothecin. Molecular docking was performed to study the binding conformations and different bonding behaviors, in order to reveal the plausible mechanism of action behind higher accumulation of active withanolide analogs with β-tubulin. The results of the present study may help in the designing of lead compound with improved activity.

Epigenetic silencing of triple negative breast cancer hallmarks by Withaferin A

Triple negative breast cancer (TNBC) is characterized by poor prognosis and a DNA hypomethylation profile. Withaferin A (WA) is a plant derived steroidal lactone which holds promise as a therapeutic agent for treatment of breast cancer (BC). We determined genome-wide DNA methylation changes in weakly-metastatic and aggressive, metastatic BC cell lines, following 72h treatment to a sub-cytotoxic concentration of WA. In contrast to the DNA demethylating agent 5-aza-2'-deoxycytidine (DAC), WA treatment of MDA-MB-231 cells rather tackles an epigenetic cancer network through gene-specific DNA hypermethylation of tumor promoting genes including ADAM metallopeptidase domain 8 (ADAM8), urokinase-type plasminogen activator (PLAU), tumor necrosis factor (ligand) superfamily, member 12 (TNFSF12), and genes related to detoxification (glutathione S-transferase mu 1, GSTM1), or mitochondrial metabolism (malic enzyme 3, ME3). Gene expression and pathway enrichment analysis further reveals epigenetic suppression of multiple cancer hallmarks associated with cell cycle regulation, cell death, cancer cell metabolism, cell motility and metastasis. Remarkably, DNA hypermethylation of corresponding CpG sites in PLAU, ADAM8, TNSF12, GSTM1 and ME3 genes correlates with receptor tyrosine-protein kinase erbB-2 amplification (HER2)/estrogen receptor (ESR)/progesterone receptor (PR) status in primary BC tumors. Moreover, upon comparing differentially methylated WA responsive target genes with DNA methylation changes in different clinical subtypes of breast cancer patients in the cancer genome atlas (TCGA), we found that WA silences HER2/PR/ESR-dependent gene expression programs to suppress aggressive TNBC characteristics in favor of luminal BC hallmarks, with an improved therapeutic sensitivity. In this respect, WA may represent a novel and attractive phyto-pharmaceutical for TNBC treatment.

Natural Withanolides in the Treatment of Chronic Diseases

Withanolides, and in particular extracts from Withania somnifera, have been used for over 3,000 years in traditional Ayurvedic and Unani Indian medical systems as well as within several other Asian countries. Traditionally, the extracts were ascribed a wide range of pharmacologic properties with corresponding medical uses, including adaptogenic, diuretic, anti-inflammatory, sedative/anxiolytic, cytotoxic, antitussive, and immunomodulatory. Since the discovery of the archetype withaferin A in 1965, approximately 900 of these naturally occurring, polyoxygenated steroidal lactones with 28-carbon ergostane skeletons have been discovered across 24 diverse structural types. Subsequently, extensive pharmacologic research has identified multiple mechanisms of action across key inflammatory pathways. In this chapter we identify and describe the major withanolides with anti-inflammatory properties, illustrate their role within essential and supportive inflammatory pathways (including NF-κB, JAK/STAT, AP-1, PPARγ, Hsp90 Nrf2, and HIF-1), and then discuss the clinical application of these withanolides in inflammation-mediated chronic diseases (including arthritis, autoimmune, cancer, neurodegenerative, and neurobehavioral). These naturally derived compounds exhibit remarkable biologic activity across these complex disease processes, while showing minimal adverse effects. As novel compounds and analogs continue to be discovered, characterized, and clinically evaluated, the interest in withanolides as a novel therapeutic only continues to grow.

Disease Subtype-Independent Biomarkers of Breast Cancer Chemoprevention by the Ayurvedic Medicine Phytochemical Withaferin A

Background

A nontoxic chemopreventive intervention efficacious against different subtypes of breast cancer is still a clinically unmet need. The present study was undertaken to determine the efficacy of an Ayurvedic medicine phytochemical (Withaferin A, [WA]) for chemoprevention of breast cancer and to elucidate its mode of action.

Methods

Chemopreventive efficacy of WA (4 and 8 mg/kg body weight) was determined using a rat model of breast cancer induced by N-methyl-N-nitrosourea (MNU; n = 14 for control group, n = 15 for 4 mg/kg group, and n = 18 for 8 mg/kg group). The mechanisms underlying breast cancer chemoprevention by WA were elucidated by immunoblotting, biochemical assays, immunohistochemistry, and cytokine profiling using plasma and tumors from the MNU-rat (n = 8-12 for control group, n = 7-11 for 4 mg/kg group, and n = 8-12 for 8 mg/kg group) and/or mouse mammary tumor virus-neu (MMTV-neu) models (n = 4-11 for control group and n = 4-21 for 4 mg/kg group). Inhibitory effect of WA on exit from mitosis and leptin-induced oncogenic signaling was determined using MCF-7 and/or MDA-MB-231 cells. All statistical tests were two-sided.

Results

Incidence, multiplicity, and burden of breast cancer in rats were decreased by WA administration. For example, the tumor weight in the 8 mg/kg group was lower by about 68% compared with controls (8 mg/kg vs control, mean = 2.76 vs 8.59, difference = -5.83, 95% confidence interval of difference = -9.89 to -1.76, P = .004). Mitotic arrest and apoptosis induction were some common determinants of breast cancer chemoprevention by WA in the MNU-rat and MMTV-neu models. Cytokine profiling showed suppression of plasma leptin levels by WA in rats. WA inhibited leptin-induced oncogenic signaling in cultured breast cancer cells.

Conclusions

WA is a promising chemopreventative phytochemical with the ability to inhibit at least two different subtypes of breast cancer.

Withaferin A induces Nrf2-dependent protection against liver injury: Role of Keap1-independent mechanisms

Small molecules of plant origin offer presumptively safe opportunities to prevent carcinogenesis, mutagenesis and other forms of toxicity in humans. However, the mechanisms of action of such plant-based agents remain largely unknown. In recent years the stress responsive transcription factor Nrf2 has been validated as a target for disease chemoprevention. Withania somnifera (WS) is a herb used in Ayurveda (an ancient form of medicine in South Asia). In the recent past, withanolides isolated from WS, such as Withaferin A (WA) have been demonstrated to be preventive and therapeutic against multiple diseases in experimental models. The goals of this study are to evaluate withanolides such as WA as well as Withania somnifera root extract as inducers of Nrf2 signaling, to probe the underlying signaling mechanism of WA and to determine whether prevention of acetaminophen (APAP)-induced hepatic toxicity in mice by WA occurs in an Nrf2-dependent manner. We observed that WA profoundly protects wild-type mice but not Nrf2-disrupted mice against APAP hepatotoxicity. WA is a potent inducer of Nrf2-dependent cytoprotective enzyme expression both in vivo and in vitro. Unexpectedly, WA induces Nrf2 signaling at least in part, in a Keap1-independent, Pten/Pi3k/Akt-dependent manner in comparison to prototypical Nrf2 inducers, sulforaphane and CDDO-Im. The identification of WA as an Nrf2 inducer that can signal through a non-canonical, Keap1-independent pathway provides an opportunity to evaluate the role of other regulatory partners of Nrf2 in the dietary and pharmacological induction of Nrf2-mediated cytoprotection.