F1012‐2 inhibits the growth of triple negative breast cancer through induction of cell cycle arrest,apoptosis, and autophagy

Sesquiterpene lactones (SLs) are plant‐derived constituents that have been proved to have potential antitumour activity. However, the intracellular molecular targets of SLs and the underlying molecular mechanisms have not been well elucidated. Here, we report that F1012‐2, a novel SL active fraction, isolated from Eupatorium lindleyanum DC., can significantly inhibit the growth of triple‐negative breast cancer (TNBC) cells (MDA‐MB‐231 and MDA‐MB‐468) but has no obvious inhibitory effect on the growth of human mammary epithelial cells (MCF‐10A). The related mechanisms on cell growth inhibition of F1012‐2 were demonstrated by inducing apoptosis in a caspase‐dependent manner through the intrinsic pathway and extrinsic pathway. F1012‐2 could also activate autophagy in TNBC cells. Simultaneously, we found that F1012‐2‐induced apoptosis was enhanced by inhibition of autophagy. Furthermore, F1012‐2 could induce cell cycle arrest at G2/M phase with decreasing expression of cyclin B1, cdc2, and upregulating p21, p‐cdc2. Also, F1012‐2 activated Akt and p38 signalling pathways. In vivo, F1012‐2 exhibited a potential antitumour effect in MDA‐MB‐231 xenografts without apparent toxicity. Taken together, our results identified that F1012‐2 inhibited cell growth via multiple signalling pathways in vitro and in vivo. These data suggest that F1012‐2 may be a potential natural active fraction for the treatment of TNBC.     

Curcumin and tetrahydrocurcumin induce cell death in Ara‐C‐resistant acute myeloid leukemia

Most anticancer agents induce cancer cell death; however, multidrug‐resistant cancers often lead to treatment failure. The effective use of curcumin as an anticancer agent has been demonstrated in clinical trials. Tetrahydrocurcumin, a major curcumin metabolite, exhibits pharmacological activities similar to those of curcumin. Curcumin induces cell death mainly through the apoptosis pathway, and tetrahydrocurcumin induces cell death mainly via an autophagy pathway in HL60 cells. Here, we investigated whether curcumin and tetrahydrocurcumin can induce apoptosis‐ and autophagy‐mediated cell deaths in Ara‐C‐resistant cancer cells, respectively. The results demonstrated that curcumin and tetrahydrocurcumin induced cell death by apoptosis and autophagy, respectively, in Ara‐C‐resistant HL60 cells. Thus, curcumin and tetrahydrocurcumin have potential applications in the treatment of acute myeloid leukemia with Ara‐C resistance.     

3,4,5‐Tricaffeoylquinic Acid Attenuates TRAIL‐induced Apoptosis in Human Keratinocytes by Suppressing Apoptosis‐related Protein Activation

Caffeoyl derivatives exhibit antiinflammatory and antioxidant effects. However, the effect of 3,4,5‐tricaffeoylquinic acid on the tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL)‐induced apoptosis in keratinocytes that may be involved in skin diseases has not been studied. In this respect, we investigated the effect of 3,4,5‐tricaffeoylquinic acid on TRAIL‐induced apoptosis in human keratinocytes. 3,4,5‐Tricaffeoylquinic acid and oxidant scavengers attenuated the decrease in the cytosolic levels of Bid, Bcl‐2, and survivin proteins; the increase in the levels of cytosolic Bax, p53, and phosphorylated p53; the increase in the levels of phosphorylated p38; the increase in the mitochondrial levels of the voltage‐dependent anion channel; loss of the mitochondrial transmembrane potential; the release of cytochrome c; activation of caspases (8, 9, and 3); cleavage of poly [ADP‐ribose] polymerase‐1; production of reactive oxygen species; the depletion of glutathione (GSH); nuclear damage; and cell death in keratinocytes treated with TRAIL. These results suggest that 3,4,5‐tricaffeoylquinic acid may reduce TRAIL‐induced apoptosis in human keratinocytes by suppressing the activation of the caspase‐8 and Bid pathways and the mitochondria‐mediated cell death pathway. The effect appears to be associated with the inhibitory effect on the production of reactive oxygen species and depletion of GSH. 3,4,5‐Tricaffeoylquinic acid appears to be effective in the prevention of TRAIL‐induced apoptosis‐mediated skin diseases. Copyright © 2015 John Wiley & Sons, Ltd.     

Bacopa monnieri‐Induced Protective Autophagy Inhibits Benzo[a]pyrene‐Mediated Apoptosis

Benzo[a]pyrene (B[a]P) is capable of inducing oxidative stress and cellular injuries leading to cell death and associates with a significant risk of cancer development. Prevention of B[a]P‐induced cellular toxicity with herbal compound through regulation of mitochondrial oxidative stress might protect cell death and have therapeutic benefit to human health. In this study, we demonstrated the cytoprotective role of Bacopa monnieri (BM) against B[a]P‐induced apoptosis through autophagy induction. Pretreatment with BM rescued the reduction in cell viability in B[a]P‐treated human keratinocytes (HaCaT) cells indicating the cytoprotective potential of BM against B[a]P. Moreover, BM was found to inhibit B[a]P‐mediated reactive oxygen species (ROS)‐induced apoptosis activation in HaCaT cells. Furthermore, BM was found to preserve mitochondrial membrane potential and inhibited release of cytochrome c in B[a]P‐treated HaCaT cells. Bacopa monnieri induced protective autophagy; we knocked down Beclin‐1, and data showed that BM was unable to protect from B[a]P‐induced mitochondrial ROS‐mediated apoptosis in Beclin‐1‐deficient HaCaT cells. Moreover, we established that B[a]P‐induced damaged mitochondria were found to colocalize and degraded within autolysosomes in order to protect HaCaT cells from mitochondrial injury. In conclusion, B[a]P‐induced apoptosis was rescued by BM treatment and provided cytoprotection through Beclin‐1‐dependent autophagy activation. Copyright © 2016 John Wiley & Sons, Ltd.     

The novel protective effects of loganin against 1‐methyl‐4‐phenylpyridinium‐induced neurotoxicity: Enhancement of neurotrophic signaling,activation of IGF‐1R/GLP‐1R,and inhibition of RhoA/ROCK pathway

Loganin, a major iridoid glycoside obtained from fruits of Cornus officinalis, possesses anti‐inflammatory, antitumor, antidiabetic, and osteoporosis prevention effects. Loganin has been linked to neuroprotection in several models of neurodegeneration, including Parkinson's disease (PD). However, mechanisms underlying the neuroprotective effects of loganin are still mostly unknown. Here, we demonstrated the protective effects of loganin against PD mimetic toxin 1‐methyl‐4‐phenylpyridinium (MPP⁺) and the important roles of insulin‐like growth factor 1 receptor (IGF‐1R) and glucagon‐like peptide 1 receptor (GLP‐1R) in the neuroprotective mechanisms of loganin. In primary mesencephalic neuronal cultures treated with or without MPP⁺, loganin up‐regulated expressions of neurotrophic signals including IGF‐1R, GLP‐1R, p‐Akt, BDNF, and tyrosine hydroxylase. Loganin protected against MPP⁺‐induced apoptosis by up‐regulating antiapoptotic protein and down‐regulating proapoptotic protein. Moreover, loganin attenuated MPP⁺‐induced neurite damage via up‐regulation of GAP43 and down‐regulation of membrane‐RhoA/ROCK2/p‐LIMK/p‐cofilin. Loganin also attenuated MPP⁺‐induced reactive oxygen species (ROS) production. However, both AG1024, an IGF‐1R antagonist, and exendin 9‐39, a GLP‐1R antagonist, attenuated the protective effects of loganin on MPP⁺‐induced cytotoxicity, apoptosis, neurite length decrease, and ROS production. Our results suggest that loganin attenuates MPP⁺‐induced apoptotic death, neurite damage, and oxidative stress through enhancement of neurotrophic signaling, activation of IGF‐1R/GLP‐1R, and inhibition of RhoA/ROCK pathway, providing the evidence that loganin possesses novel neuroprotective effects.     

Ramalin‐Mediated Apoptosis Is Enhanced by Autophagy Inhibition in Human Breast Cancer Cells

Breast cancer, the most commonly diagnosed cancer in women worldwide, is treated in various ways. Ramalin is a chemical compound derived from the Antarctic lichen Ramalina terebrata and is known to exhibit antioxidant and antiinflammatory activities. However, its effect on breast cancer cells remains unknown. We examined the ability of ramalin to induce apoptosis and its mechanisms in MCF‐7 and MDA‐MB‐231 human breast cancer cell lines. Ramalin inhibited cell growth and induced apoptosis in both cell lines in a concentration‐dependent manner. By upregulating Bax and downregulating Bcl‐2, ramalin caused cytochrome c and apoptosis‐inducing factor to be released from the mitochondria into the cytosol, thus activating the mitochondrial apoptotic pathway. In addition, activated caspase‐8 and caspase‐9 were detected in both types of cells exposed to ramalin, whereas ramalin activated caspase‐3 only in the MDA‐MB‐231 cells. Ramalin treatment also increased the levels of LC3‐II and p62. Moreover, the inhibition of autophagy by 3‐methyladenine or Atg5 siRNA significantly enhanced ramalin‐induced apoptosis, which was accompanied by a decrease in Bcl‐2 levels and an increase in Bax levels. Therefore, autophagy appears to be activated as a protective mechanism against apoptosis in cancer cells exposed to ramalin. These findings suggest that ramalin is a potential anticancer agent for the treatment of patients with non‐invasive or invasive breast cancer. Copyright © 2015 John Wiley & Sons, Ltd.     

Retracted: Baicalin relieves TNF‐α‐evoked injury in human aortic endothelial cells by up‐regulation of miR‐145

Hypertension is recognized to be associated with low‐grade inflammation. Baicalin (BAI) is reported to possess various pharmacological including anti‐inflammatory activities. This research explored the molecular mechanism by which BAI functions in human aortic endothelial cells (HAECs). HAECs were pretreated with BAI. Cell viability, apoptosis, and expressions of crucial proteins were respectively evaluated using cell counting kit‐8 assay, flow cytometry, and western blot. Productions of cytokines were respectively assessed employing quantitative real‐time polymerase chain reaction and enzyme‐linked immunosorbent assay. Cell transfection was utilized to alter miR‐145 expression. The expressions of proteins participated in JNK and p38MAPK pathways were analyzed utilizing western blot. TNF‐α inducement successfully evoked inflammatory injury in HAECs, exhibiting as prominently suppressed viability, while facilitated apoptosis and productions of cytokines. However, BAI pretreatment significantly ameliorated TNF‐α‐triggered inflammatory injuries. Besides, miR‐145 expression was markedly inhibited by TNF‐α inducement, while notably elevated by BAI pretreatment. Although miR‐145 overexpression had no significant influence on apoptosis, miR‐145 silence observably reversed BAI pretreatment‐evoked protective influences on TNF‐α‐induced HAECs, as well as the inhibited impacts on the levels of key proteins involved in JNK and p38MAPK pathways. This investigation illustrated that BAI relieved TNF‐α‐triggered injuries through upregulating miR‐145 via suppressing JNK and p38MAPK pathways.     

Apoptosis Induction by 13‐Acetoxyrolandrolide through the Mitochondrial Intrinsic Pathway

The aim of this study was to evaluate the mechanisms of cytotoxicity of the sesquiterpene lactone 13‐acetoxyrolandrolide, a nuclear factor kappa B (NF‐κB) inhibitor that was previously isolated from Rolandra fruticosa. The effects associated with the inhibition of the NF‐κB pathway included dose‐dependent inhibition of the NF‐κB subunit p65 (RelA) and inhibition of upstream mediators IKKβ and oncogenic Kirsten rat sarcoma (K‐Ras). The inhibitory concentration of 13‐acetoxyrolandrolide on K‐Ras was 7.7 µm . The downstream effects of the inhibition of NF‐κB activation were also investigated in vitro. After 24 h of treatment with 13‐acetoxyrolandrolide, the mitochondrial transmembrane potential was depolarized in human colon cancer (HT‐29) cells. The mitochondrial oxidative phosphorylation was also negatively affected, and reduced levels of nicotinamine adenine dinucleotide phosphate (NAD(P)H) were detected after 2 h of 13‐acetoxyrolandrolide exposure. Furthermore, the expression of the pro‐apoptotic protein caspase‐3 increased in a concentration‐dependent manner. Cell flow cytometry showed that 13‐acetoxyrolandrolide induced cell cycle arrest at G₁, indicating that the treated cells had undergone caspase‐3‐mediated apoptosis, indicating negative effects on cancer cell proliferation. These results suggest that 13‐acetoxyrolandrolide inhibits NF‐κB and K‐Ras and promotes cell death mediated through the mitochondrial apoptotic pathway. Copyright © 2013 John Wiley & Sons, Ltd.     

Graveoline Isolated from Ethanolic Extract of Ruta graveolens Triggers Apoptosis and Autophagy in Skin Melanoma Cells: A Novel Apoptosis‐Independent Autophagic Signaling Pathway

Anti‐cancer drugs generally kill cancer cells by apoptosis but fail to do so when they become resistant and escape apoptosis signals. But these resistant cells can still be killed by autophagy. Therefore, drugs having both apoptotic and autophagic abilities are solicited in effective cancer management. In search of such a drug, we examined the efficacy of graveoline, a bioactive compound isolated from Ruta graveolens on skin melanoma A375 cells through the use of specific signaling cascades and their inhibitors. Cytotoxicity of graveoline was tested by conducting MTT assay. Induction of autophagy and apoptosis was checked. Expression of related proteins and their localization were studied by conducting immunoblot assay and through confocal microscopy, respectively. We found graveoline‐induced Beclin‐1 associated autophagy in A375 cells and 3‐methyladenine, an inhibitor of autophagy did not affect apoptosis. Conversely, caspase inhibitor that blocked apoptosis did not affect autophagic cell death, suggesting thereby that these two were independent events. Use of reactive oxygen species (ROS) scavengers inhibited cell death, but blocking autophagy did not affect graveoline‐induced ROS generation, suggesting that ROS generation ensued autophagy. Thus, graveoline‐induced both apoptotic and autophagic cell death in skin melanoma cells, a desirable quality in effective anti‐cancer drug design. Copyright © 2013 John Wiley & Sons, Ltd.     

Phloroglucinol Protects INS‐1 Pancreatic β‐cells Against Glucotoxicity‐Induced Apoptosis

Decreasing numbers, and impaired function, of pancreatic β‐cells are key factors in the development of type 2 diabetes. This study was designed to investigate whether phloroglucinol protected pancreatic β‐cells against glucotoxicity‐induced apoptosis using a rat insulinoma cell line (INS‐1). High glucose treatment (30 mM) induced INS‐1 cell death; however, the level of glucose‐induced apoptosis was significantly reduced in cells treated with 100‐μM phloroglucinol. Treatment with 10–100‐μM phloroglucinol increased cell viability and decreased intracellular levels of reactive oxygen species, nitric oxide, and lipid peroxidation dose‐dependently in INS‐1 cells pretreated with high glucose. Furthermore, phloroglucinol treatment markedly reduced the protein expression of Bax, cytochrome c, and caspase 9, while increasing anti‐apoptotic Bcl‐2 protein expression. Cell death type was examined using annexin V/propidium iodide staining, revealing that phloroglucinol markedly reduced high glucose‐induced apoptosis. These results demonstrated that phloroglucinol could be useful as a potential therapeutic agent for the protection of pancreatic β‐cells against glucose‐induced apoptosis. Copyright © 2015 John Wiley & Sons, Ltd.     

Chelidonine inhibits TNF‐α‐induced inflammation by suppressing the NF‐κB pathways in HCT116 cells

Nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NF‐κB) is a complex that regulates several hundreds of genes, including those involved in immunity and inflammation, survival, proliferation, and the negative feedback of NF‐κB signaling. Chelidonine, a major bioactive, isoquinoline alkaloid ingredient in Chelidonium majus, exhibits antiinflammatory pharmacological properties. However, its antiinflammatory molecular mechanisms remain unclear. In this work, we explored the effect of chelidonine on TNF‐induced NF‐κB activation in HCT116 cells. We found chelidonine inhibited the phosphorylation and degradation of the inhibitor of NF‐κB alpha and nuclear translocation of RELA. Furthermore, by inhibiting the activation of NF‐κB, chelidonine downregulated target genes involved in inflammation, proliferation, and apoptosis. Chelidonine also inhibited mitogen‐activated protein kinase pathway activation by blocking c‐Jun N‐terminal kinase and p38 phosphorylation. These results suggest that chelidonine may be a potential therapeutic agent against inflammatory diseases in which inhibition of NF‐κB activity plays an important role.     

Paris saponin VII induces cell cycle arrest and apoptosis by regulating Akt/MAPK pathway and inhibition of P‐glycoprotein in K562/ADR cells

Paris saponinVII (PSVII) is a steroidal saponin isolated from the roots and rhizomes of Trillium tschonoskii Maxim. We found that PSVII could inhibit the growth of adriamycin‐resistant human leukemia cells (K562/ADR) in a dose‐dependent manner. Furthermore, the molecular mechanism underlying the cytotoxicity and downregulation of P‐glycoprotein (P‐gp) expression by PSVII was clarified. PSVII significantly suppressed cell proliferation by cell cycle arrest in the G0/G1 phase, which was associated with an obvious decrease in cyclin B1/D1 and CDK2/4/6 protein expression. Moreover, PSVII could attenuate mitochondrial membrane potential, increase the expression of apoptosis‐related proteins, such as Bax and cytochrome c, and decrease the protein expression levels of Bcl‐2, caspase‐9, caspase‐3, PARP‐1, and p‐Akt. We also found that JNK, ERK1/2, and p38 were regulated by PSVII in K562/ADR cells. And further studies indicated that the decrease in the reactive oxygen species level inhibited intrinsic P‐gp expression. Therefore, PSVII‐induced apoptosis in K562/ADR cells was associated with Akt/MAPK and the inhibition of P‐gp. In addition, PSVII induced a robust autophagy in K562/ADR cells as demonstrated by the degradation of LC3‐I. These results provide a biochemical basis for possible clinical applications of PSVII in the treatment of leukemia.     

A New Isoflavone Glycitein 7‐O‐beta‐d‐Glucoside 4'‐O‐methylate,isolated from Cordyceps militaris grown on Germinated Soybeans Extract,Inhibits EGF‐induced Mucus Hypersecretion in the Human Lung Mucoepidermoid Cells

A new isoflavone glycitein 7‐O‐beta‐d ‐glucoside 4''‐O‐methylate (CGLM) has been isolated recently from Cordyceps militaris grown on germinated soybean extract and has antioxidant activity. In the present study, CGLM was investigated for its suppression of airway mucous hyper‐secretion in epidermal growth factor (EGF)‐treated human lung mucoepidermoid cells. NCI‐H292 cells were treated with CGLM for 1 h, followed by EGF treatment for 24 h. The decrease in cyclooxygenase‐2 (COX‐2) production was correlated with reduced levels of protein and mRNA of inducible matrix metalloproteinase 9 (MMP‐9) and also MUC5AC gene expression. CGLM directly inhibited down‐regulated NF‐κB activity, and significantly inhibited the phosphorylation of p38 and ERK1/2 (p42/p44) in NCI‐H292 cells. These results suggest that CGLM protects NCI‐H292 cells from EGF‐induced damage by down‐regulation of COX‐2, MMP‐9 and MUC5AC gene expression, mediated via blocking the NF‐kappa‐B and p38/ERK MAPK pathways. Copyright © 2012 John Wiley & Sons, Ltd.     

α‐Hederin induces the apoptosis of gastric cancer cells accompanied by glutathione decrement and reactive oxygen species generation via activating mitochondrial dependent pathway

α‐Hederin, a monodesmosidic triterpenoid saponin, exhibited promising antitumor potential against a variety of human cancer cell lines. However, few related studies about effects of α‐hederin on gastric cancer are available. Herein, our results showed that α‐hederin significantly inhibited the proliferation of gastric cancer cells and arrested the cell cycle in G1 phase in vitro (p < .05). Further research of the potential mechanism reflected that α‐hederin could induce intracellular glutathione decrement, adenosine triphosphate level, and mitochondrial membrane potential variation via inducing reactive oxygen species accumulation during the apoptosis of gastric cancer cells. Moreover, the detection of mitochondrial and cytosol proteins with apoptosis‐inducing factor, apoptosis protease activating factor‐1, and cytochrome C showed an increase in the cytosol, followed by a decrease of Bcl‐2 levels and increases of caspase‐3, caspase‐8, caspase‐9, and Bax, which revealed that α‐hederin induced apoptosis via triggering activation of the mitochondrial pathway. Furthermore, the above changes were amplified when pretreated with buthionine sulfoximine, whereas attenuated in the group pretreated with NAC than α‐hederin alone (p < .05). In addition, α‐hederin significantly inhibited the growth of xenografted gastric tumors with favorable safety. In conclusion, α‐hederin could inhibit the proliferation and induce apoptosis of gastric cancer accompanied by glutathione decrement and reactive oxygen species generation via activating mitochondrial dependent pathway.     

The Novel p53‐Dependent Metastatic and Apoptotic Pathway Induced by Vitexin in Human Oral Cancer OC2 Cells

Vitexin, identified as apigenin‐8‐C‐D‐glucopyranoside, a natural flavonoid compound found in certain herbs such as hawthorn herb, has been reported to exhibit anti‐oxidative, anti‐inflammatory, anti‐metastatic and antitumor properties. The aim of this study was to investigate the possible existence of p53‐dependent pathway underlying vitexin‐induced metastasis and apoptosis in human oral cancer cells, OC2 cells. Vitexin decreased cell viability significantly. Meanwhile, the expression of tumor suppressor p53 and a small group of its downstream genes, p21 ^WAF1 and Bax, were upregulated. The p53 inhibitor pifithrin‐α (PFT‐α) knockdown of the signaling of p53 led vitexin to lose its antitumor effect and inhibited the expression of p53 downstream genes, p21^WAF1 and Bax. Vitexin had anti‐metastatic potential accompanied with increasing plasminogen activator inhibitor 1 (PAI‐1) accumulation and decreasing matrix metalloproteinase‐2 expression. Our present study evidenced, by using p53 inhibitor PFT‐α, PAI‐1 and peroxisome proliferator‐activated receptor γ are downstream genes of p53 in vitexin‐induced signaling. MAPK inhibitor PD98059 decreased the OC2 cells viability significantly. The expression of p53 and its downstream genes p21 ^WAF1 and Bax were enhanced by blocking the activation of p42/p44 MAPK in response to treatment with vitexin. Moreover, p42/p44 MAPK played a negative role in p53‐dependent metastasis and apoptosis. We give evidence for the first time that the novel p53‐dependent metastatic and apoptotic pathway induced by vitexin in human oral cancer OC2 cells. Copyright © 2012 John Wiley & Sons, Ltd.     

Tanshinone IIA combined with cisplatin synergistically inhibits non‐small‐cell lung cancer in vitro and in vivo via down‐regulating the phosphatidylinositol 3‐kinase/Akt signalling pathway

Cisplatin represents one of the first‐line drugs used for non‐small‐cell lung cancer treatment. However, considerable side effects and the emergence of drug resistance are becoming critical limitations to its application. Combinatorial strategies may be able to extend the use of cisplatin. Both Tanshinone IIA and cisplatin inhibit non‐small‐cell lung cancer cell growth in a time‐ and dose‐dependent manner. When Tanshinone IIA was combined with cisplatin at a ratio of 20:1, they were observed to exert a synergistic inhibitory effect on non‐small‐cell lung cancer cells. The combination treatment was shown to impair cell migration and invasion, arrest the cell cycle in the S phases, and induce apoptosis in A549 and PC9 cells in a synergistic manner. KEGG pathway analysis and molecular docking indicated that Tanshinone IIA might mainly influence the phosphatidylinositol 3‐kinase‐Akt signalling pathway. In all treated groups, the expression levels of Bax and cleaved Caspase‐3 were up‐regulated, whereas the expression levels of Bcl‐2, Caspase‐3, p‐Akt, and p‐PI3K proteins were down‐regulated. Among these, the combination of Tan IIA and cisplatin exhibited the most significant difference. Tanshinone IIA may function as a novel option for combination therapy for non‐small‐cell lung cancer treatment.     

Turmeric Toxicity in A431 Epidermoid Cancer Cells Associates with Autophagy Degradation of Anti‐apoptotic and Anti‐autophagic p53 Mutant

The keratinocyte‐derived A431 Squamous Cell Carcinoma cells express the p53R273H mutant, which has been reported to inhibit apoptosis and autophagy. Here, we show that the crude extract of turmeric (Curcuma longa), similarly to its bioactive component Curcumin, could induce both apoptosis and autophagy in A431 cells, and these effects were concomitant with degradation of p53. Turmeric and curcumin also stimulated the activity of mTOR, which notoriously promotes cell growth and acts negatively on basal autophagy. Rapamycin‐mediated inhibition of mTOR synergized with turmeric and curcumin in causing p53 degradation, increased the production of autophagosomes and exacerbated cell toxicity leading to cell necrosis. Small‐interference mediated silencing of the autophagy proteins BECLIN 1 or ATG7 abrogated the induction of autophagy and largely rescued p53 stability in Turmeric‐treated or Curcumin‐treated cells, indicating that macroautophagy was mainly responsible for mutant p53 degradation. These data uncover a novel mechanism of turmeric and curcumin toxicity in chemoresistant cancer cells bearing mutant p53. Copyright © 2014 John Wiley & Sons, Ltd.