withaferin-a and Glioblastoma

Within the Ayurvedic medical tradition of India, Ashwagandha (Withania somnifera) is a well-known herb. A large number of withanolides have been isolated from both its roots and its leaves and many have been assessed for their pharmacological activities. Amongst them, Withaferin A is one of its most bioactive phytoconstituents. Due to the lactonal steroid's potential to modulate multiple oncogenic pathways, Withaferin A has gained much attention as a possible anti-neoplastic agent. This review focuses on the use of Withaferin A alone, or in combination with other treatments, as a newer option for therapy against the most aggressive variant of brain tumors, Glioblastoma. We survey the various studies that delineate Withaferin A's anticancer mechanisms, its toxicity profiles, its pharmacokinetics and pharmacodynamics and its immuno-modulating properties.

Topics: Antineoplastic Agents; Brain Neoplasms; Glioblastoma; Humans; Treatment Outcome; Withanolides

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.. 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.. 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.

Topics: Activating Transcription Factor 3; Activating Transcription Factor 4; Animals; Cell Line, Tumor; G2 Phase Cell Cycle Checkpoints; Glioblastoma; Humans; M Phase Cell Cycle Checkpoints; Mice; Mice, Nude; Neoplasm Proteins; Signal Transduction; Transcription Factor CHOP; Withanolides; Xenograft Model Antitumor Assays

Glioblastoma multiforme (GBM) is an aggressive, malignant cancer Johnson and O'Neill (J Neurooncol 107: 359-364, 2012). An extract from the winter cherry plant (Withania somnifera ), AshwaMAX, is concentrated (4.3 %) for Withaferin A; a steroidal lactone that inhibits cancer cells Vanden Berghe et al. (Cancer Epidemiol Biomark Prev 23: 1985-1996, 2014). We hypothesized that AshwaMAX could treat GBM and that bioluminescence imaging (BLI) could track oral therapy in orthotopic murine models of glioblastoma. Human parietal-cortical glioblastoma cells (GBM2, GBM39) were isolated from primary tumors while U87-MG was obtained commercially. GBM2 was transduced with lentiviral vectors that express Green Fluorescent Protein (GFP)/firefly luciferase fusion proteins. Mutational, expression and proliferative status of GBMs were studied. Intracranial xenografts of glioblastomas were grown in the right frontal regions of female, nude mice (n = 3-5 per experiment). Tumor growth was followed through BLI. Neurosphere cultures (U87-MG, GBM2 and GBM39) were inhibited by AshwaMAX at IC50 of 1.4, 0.19 and 0.22 µM equivalent respectively and by Withaferin A with IC50 of 0.31, 0.28 and 0.25 µM respectively. Oral gavage, every other day, of AshwaMAX (40 mg/kg per day) significantly reduced bioluminescence signal (n = 3 mice, p < 0.02, four parameter non-linear regression analysis) in preclinical models. After 30 days of treatment, bioluminescent signal increased suggesting onset of resistance. BLI signal for control, vehicle-treated mice increased and then plateaued. Bioluminescent imaging revealed diffuse growth of GBM2 xenografts. With AshwaMAX, GBM neurospheres collapsed at nanomolar concentrations. Oral treatment studies on murine models confirmed that AshwaMAX is effective against orthotopic GBM. AshwaMAX is thus a promising candidate for future clinical translation in patients with GBM.

Topics: Animals; Antineoplastic Agents; Brain Neoplasms; Cell Line, Tumor; Cell Proliferation; Cell Survival; Disease Models, Animal; Dose-Response Relationship, Drug; ErbB Receptors; Female; Glioblastoma; Humans; Luminescent Measurements; Mice; Mice, Nude; Neural Stem Cells; Plant Extracts; Withania; Withanolides; Xenograft Model Antitumor Assays

Temozolomide (TMZ) has remained the chemotherapy of choice in patients with glioblastoma multiforme (GBM) primarily due to the lack of more effective drugs. Tumors, however, quickly develop resistance to this line of treatment creating a critical need for alternative approaches and strategies to resensitize the cells. Withaferin A (WA), a steroidal lactone derived from several genera of the Solanaceae plant family has previously demonstrated potent anti-cancer activity in multiple tumor models. Here, we examine the effects of WA against TMZ-resistant GBM cells as a monotherapy and in combination with TMZ. WA prevented GBM cell proliferation by dose-dependent G2/M cell cycle arrest and cell death through both intrinsic and extrinsic apoptotic pathways. This effect correlated with depletion of principle proteins of the Akt/mTOR and MAPK survival and proliferation pathways with diminished phosphorylation of Akt, mTOR, and p70 S6K but compensatory activation of ERK1/2. Depletion of tyrosine kinase cell surface receptors c-Met, EGFR, and Her2 was also observed. WA demonstrated induction of N-acetyl-L-cysteine-repressible oxidative stress as measured directly and through a subsequent heat shock response with HSP32 and HSP70 upregulation and decreased HSF1. Finally, pretreatment of TMZ-resistant GBM cells with WA was associated with O6-methylguanine-DNA methyltransferase (MGMT) depletion which potentiated TMZ-mediated MGMT degradation. Combination treatment with both WA and TMZ resulted in resensitization of MGMT-mediated TMZ-resistance but not resistance through mismatch repair mutations. These studies suggest great clinical potential for the utilization of WA in TMZ-resistant GBM as both a monotherapy and a resensitizer in combination with the standard chemotherapeutic agent TMZ.

Topics: Antineoplastic Agents; Apoptosis; Cell Cycle Checkpoints; Cell Death; Cell Line, Tumor; Cell Proliferation; Dacarbazine; DNA Modification Methylases; DNA Repair Enzymes; ErbB Receptors; G2 Phase Cell Cycle Checkpoints; Glioblastoma; Heme Oxygenase-1; Humans; MAP Kinase Signaling System; O(6)-Methylguanine-DNA Methyltransferase; Oxidative Stress; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-met; Receptor, ErbB-2; Ribosomal Protein S6 Kinases, 70-kDa; Temozolomide; TOR Serine-Threonine Kinases; Tumor Suppressor Proteins; Withanolides

Withaferin A (WA), a steroidal lactone derived from the plant Vassobia breviflora, has been reported to have anti-proliferative, pro-apoptotic, and anti-angiogenic properties against cancer growth. In this study, we identified several key underlying mechanisms of anticancer action of WA in glioblastoma cells. WA was found to inhibit proliferation by inducing a dose-dependent G2/M cell cycle arrest and promoting cell death through both intrinsic and extrinsic apoptotic pathways. This was accompanied by an inhibitory shift in the Akt/mTOR signaling pathway which included diminished expression and/or phosphorylation of Akt, mTOR, p70 S6K, and p85 S6K with increased activation of AMPKα and the tumor suppressor tuberin/TSC2. Alterations in proteins of the MAPK pathway and cell surface receptors like EGFR, Her2/ErbB2, and c-Met were also observed. WA induced an N-acetyl-L-cysteine-repressible enhancement in cellular oxidative potential/stress with subsequent induction of a heat shock stress response primarily through HSP70, HSP32, and HSP27 upregulation and HSF1 downregulation. Taken together, we suggest that WA may represent a promising chemotherapeutic candidate in glioblastoma therapy warranting further translational evaluation.

Topics: Animals; Antineoplastic Agents; Cell Cycle; Cell Death; Cell Line, Tumor; Cell Proliferation; DNA-Binding Proteins; Glioblastoma; Heat Shock Transcription Factors; Heat-Shock Proteins; Heat-Shock Response; Humans; Mice; Oxidative Stress; Proto-Oncogene Proteins c-akt; Reactive Oxygen Species; Signal Transduction; TOR Serine-Threonine Kinases; Transcription Factors; Withanolides

Ashwagandha (Withania somnifera) is widely used in the Indian traditional system of medicine, Ayurveda. Although it is claimed to have a large variety of health-promoting effects, including therapeutic effects on stress and disease, the mechanisms of action have not yet been determined. In the present study, we aimed to investigate the growth inhibition and differentiation potential of the alcoholic extract of Ashwagandha leaves (i-Extract), its different constituents (Withaferin A, Withanone, Withanolide A) and their combinations on glioma (C6 and YKG1) cell lines. Withaferin A, Withanone, Withanolide A and i-Extract markedly inhibited the proliferation of glioma cells in a dose-dependent manner and changed their morphology toward the astrocytic type. Molecular analysis revealed that the i-Extract and some of its components caused enhanced expression of glial fibrillary acidic protein, change in the immunostaining pattern of mortalin from perinuclear to pancytoplasmic, delay in cell migration, and increased expression of neuronal cell adhesion molecules. The data suggest that the i-Extract and its components have the potential to induce senescence-like growth arrest and differentiation in glioma cells. These assays led us to formulate a unique combination formula of i-Extract components that caused enhanced differentiation of glial cells.

Topics: Blotting, Western; Cell Cycle; Cell Differentiation; Cell Movement; Cell Proliferation; Drug Therapy, Combination; Ergosterol; Glioblastoma; Humans; Phytotherapy; Plant Extracts; Plant Leaves; Tumor Cells, Cultured; Withania; Withanolides