The Effect of Ethanol Extract from Mesua ferrea Linn Flower on Alzheimer's Disease and Its Underlying Mechanism.

The effects of Mesua ferrea Linn flower (MFE) extract on the pathogenic cascade of Alzheimer's disease (AD) were determined by an in vitro and cell culture model in the search for a potential candidate for the treatment of AD. The 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay exhibited that the MFE extract had antioxidant activities. According to the Ellman and the thioflavin T method's result, the extracts could inhibit acetylcholinesterase and ß-amyloid (Aß) aggregation. Studies on neuroprotection in cell culture found that the MFE extract could reduce the death of human neuroblastoma cells (SH-SY5Y) caused by H2O2 and Aß. Western blot analysis exhibited that the MFE extract alleviated H2O2-induced neuronal cell damage by downregulating the pro-apoptotic proteins, including cleaved caspase-3, Bax, and by enhancing the expression of anti-apoptotic markers including MCl1, BClxl, and survivin. Moreover, MFE extract inhibited the expression of APP, presenilin 1, and BACE, and increased the expression of neprilysin. In addition, the MFE extract could enhance scopolamine-induced memory deficit in mice. Overall, results showed that the MFE extract had several modes of action related to the AD pathogenesis cascade, including antioxidants, anti-acetylcholinesterase, anti-Aß aggregation, and neuroprotection against oxidative stress and Aß. Therefore, the M. ferrea L. flower might be a possibility for further development as a medication for AD.

7-Methoxyheptaphylline Enhances TRAIL-Induced Apoptosis of Colorectal Adenocarcinoma Cell via JNK-Mediated DR5 Expression.

A cytokine known as tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) has the ability to precisely cause the death of cancer cells, while normal cells are left undisturbed. Recent studies show that certain cancer cells are sensitive to the apoptotic effect of TRAIL. In this study, HT29 colorectal adenocarcinoma cells exposed to TRAIL were treated with heptaphylline and 7-methoxyheptaphylline from Clausena harmandiana in an effort to comprehend the mechanisms involved behind this activity. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) test was utilized to determine cell survival, and phase contrast microscopy was used to examine cell morphology. Through using real-time RT-PCR, Western blotting, and RT-PCR, the molecular mechanisms were investigated. According to the findings, whilst hepataphylline caused cytotoxicity in normal colon FHC cells, in comparison to healthy colon FHC cells, 7-methoxyheptaphylline inhibited cancer cells in a concentration-dependent manner. Heptaphylline alone or in conjunction with TRAIL showed no discernible effect on TRAIL-induced HT29 cell death, but 7-methoxyheptaphylline boosted caspase-3 cleavage. The study showed that the c-Jun N-terminal kinase (JNK) pathway was responsible for the 7-methoxyheptaphylline's enhancement of the death receptor 5 (DR5) mRNA, TRAIL receptor, and protein. The results demonstrated that the 7-methoxyheptaphylline of Clausena harmandiana increased the expression of DR5 via the JNK pathway, intensifying TRAIL-induced HT29 cell death.

Nordentatin Inhibits Neuroblastoma Cell Proliferation and Migration through Regulation of GSK-3 Pathway.

Cancer is caused by abnormal cell changes leading to uncontrolled cell growth. The specific characteristics of cancer cells, including the loss of apoptotic control and the ability to migrate into and invade the surrounding tissue, result in cancer cell metastasis to other parts of the body. Therefore, the inhibition of the proliferation, migration, and invasion of cancer cells are the principal goals in the treatment of cancer. This study aimed to investigate the inhibitory activity of nordentatin, a coumarin derivative isolated from Clausena harmandiana, regarding the proliferation and migration of human neuroblastoma cells (SH-SY5Y). Nordentatin at a concentration of 100 µM showed cell cytotoxicity toward SH-SY5Y that was significantly different from that of the control group (p < 0.01) at 24, 48, and 72 h. Moreover, nordentatin inhibited SH-SY5Y proliferation by inhibiting the antiapoptotic protein Mcl-1, leading to the cleavage of caspase-3 and resulting in the inhibition of a migratory protein, MMP-9, through the GSK-3 pathway (compared with cells treated with a GSK inhibitor). These results suggest that nordentatin inhibited the proliferation and migration of neuroblastoma cells through the GSK-3 pathway.

Multifunctionality of Clausena harmandiana Extract and Its Active Constituents against Alzheimer's Disease.

This study was designed to investigate the effects of the root-bark extract of Clausena harmandiana (CH) and its active constituents (nordentatin and 7-methoxyheptaphylline) on pharmacological activities regarding selected targets associated with AD, namely, its antioxidant activity, inhibition of Aß aggregation, acetylcholinesterase (AChE) activity, and neuroprotective effects. The effect of the CH extract on the cognitive impairment induced by scopolamine was also evaluated in mice. The effects of the CH extract and its active constituents on radical scavenging, Aß aggregation, and AChE activity were investigated with a 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) assay, a thioflavin-T assay, and Ellman's method. The neuroprotective effects of the extract against hydrogen-peroxide and Aß toxicity were evaluated with a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. In addition, the effects on cognitive impairment induced by scopolamine in mice were evaluated using Morris-water-maze and modified-Y-maze test models. The results of the present study demonstrate that the root-bark extract of CH shows multimodal actions relevant to the AD pathological cascade, including antioxidant effects, the inhibition of Aß aggregation, the inhibition of AChE function, and neuroprotection against oxidative stress and Aß toxicity. The extracts could improve both the short- and long-term memory deficits induced by scopolamine in mice.

Acridone Derivatives from Atalantia monophyla Inhibited Cancer Cell Proliferation through ERK Pathway.

The present study aimed to investigate the effect of acridone alkaloids on cancer cell lines and elucidate the underlying molecular mechanisms. The ten acridone alkaloids from Atalantia monophyla were screened for cytotoxicity against LNCaP cell lines by a WST-8 assay. Then, the most potential acridone, buxifoliadine E, was evaluated on four types of cancer cells, namely prostate cancer (LNCaP), neuroblastoma (SH SY5Y), hepatoblastoma (HepG2), and colorectal cancer (HT29). The results showed that buxifoliadine E was able to significantly inhibit the proliferation of all four types of cancer cells, having the most potent cytotoxicity against the HepG2 cell line. Western blotting analysis was performed to assess the expression of signaling proteins in the cancer cells. In HepG2 cells, buxifoliadine E induced changes in the levels of Bid as well as cleaved caspase-3 and Bax through MAPKs, including Erk and p38. Moreover, the binding interaction between buxifoliadine E and Erk was investigated by using the Autodock 4.2.6 and Discovery Studio programs. The result showed that buxifoliadine E bound at the ATP-binding site, located at the interface between the N- and C-terminal lobes of Erk2. The results of this study indicate that buxifoliadine E suppressed cancer cell proliferation by inhibiting the Erk pathway.

Candidone Inhibits Migration and Invasion, and Induces Apoptosis in HepG2 Cells.

The aim of the study was to investigate the inhibitory activity of candidone, the active constituent of Derris (D.) indica, on the proliferation, migration, and invasiveness of human hepatoblastoma (HepG2) cells. Cancer cell death was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and apoptosis-associated morphological changes were observed by phase contrast microscopy. Additionally, Western blotting was used to study protein expression following treatment with candidone, and transwell migration and invasion assays were used for observing cancer cell migration and invasiveness, respectively. The results suggest that candidone possesses potent inhibitory activity against HepG2 cells (concentration, 100 µM; 24 h treatment). Cancer cells treated with candidone exhibited apoptosis-associated changes, including detachment, cell shrinkage and death. Furthermore, candidone was shown to promote cell death by activating caspase-3 and -9, and decreasing the expression of antiapoptotic proteins, including p65, induced myeloid leukemia cell differentiation protein Mcl-1, B-cell lymphoma 2 (Bcl2), Bcl2-associated agonist of cell death and survivin. Moreover, candidone inhibited the migration and invasion abilities of HepG2 cells and decreased the levels of proteins associated with these processes, including phospho-p38 and active matrix metallopeptidase 9. Collectively, the results of the present study indicate that candidone is able to inhibit the proliferation, migration and invasive potential of HepG2 cells.

Neuroprotective and anticancer effects of 7­Methoxyheptaphylline via the TAK1 pathway.

7­Methoxyheptaphylline (7­MH) is a carbazole extracted from Clausena harmandiana, a medicinal plant that is used to treat headaches and stomachaches. The aim of the present study was to examine the neuroprotective effects and anticancer activity of 7­MH. Cell death was assessed using an MTT assay and flow cytometry. The expression of apoptosis­related proteins was determined by western blot analysis. An animal model was used to test anti­metastasis. The interactions between 7­MH and the molecular target were observed using molecular docking. The results revealed that 7­MH provided protection against hydrogen peroxide (H2O2)­induced neuronal cell death. In cancer cells, 7­MH induced SH­SY5Y, 4T1, HT29, HepG2, and LNCaP cell death. 7­MH inhibited metastasis of HT29 cells in vitro and 4T1­Luc cells in vitro and in vivo. 7­MH inhibited proteins, including P­glycogen synthase kinase (GSK)­3, and cleaved caspase­3, but it activated anti­apoptotic proteins in H2O2­induced SH­SY5Y cell death. By contrast, 7­MH activated the cleaving of caspase­3 and GSK­3, but it suppressed anti­apoptotic proteins in SH­SY5Y cells. 7­MH reduced the levels of NF­κB and STAT3 in 4T1 cells; phospho­p65, Erk, and MAPK13 in LNCaP cells; and phospho­Erk and matrix metalloproteinase­9 in HT29 cells. Molecular docking analysis showed that 7­MH targets TAK1 kinase. The present study indicated that 7­MH induced apoptosis of cancer cells and provided protection against H2O2­induced neuron cell death via TAK1 kinase.

Multifunctional effect of flavonoids from Millettia brandisiana against Alzheimer's disease pathogenesis.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by cognitive impairment and neuronal death. Fifteen flavonoids from Millettia brandisiana were evaluated for the multifunctional effect against AD pathogenesis, including butyrylcholine esterase (BuChE) inhibition, anti-amyloid beta (Aß) aggregation and neuroprotection against hydrogen peroxide (H2O2) toxicity in differentiated human neuroblastoma SH-SY5Y cell. To understand the mechanism and structure-activity relationship, binding interactions between flavonoids and the BuChE and Aß were investigated in silico. Furthermore, drug-likeness properties and ADMET parameters were evaluated in silico using SwissADME and pKCSM tools. All flavonoids exhibit a good drug-likeness profile. Six flavonoids have potency in BuChE inhibition, and four flavonoids show potency in anti-Aß aggregation. Flavonoids with the 6″,6″-dimethylchromeno- [2″,3″:7,8]-flavone structure show a favorable multifunctional effect. In silico analysis showed that flavonoids can bind in various positions to the catalytic triad, anionic site, and acyl pocket. In Aß1-42, potential flavonoids can attach to the central hydrophobic region and the C terminal hydrophobic and interfere with Aß interchain hydrogen binding. When compared together, it can inhibit multifunctional action with a favorable ADMET parameter and drug-likeness profile. In addition, candidine can prevent neuronal damage in differentiated SH-SY5Y neuroblastoma cells induced by H2O2 in a dose-dependent manner.

Gomisin A enhances tumor necrosis factor-α-induced G1 cell cycle arrest via signal transducer and activator of transcription 1-mediated phosphorylation of retinoblastoma protein.

Gomisin A, a dibenzocyclooctadiene lignan isolated from the fruit of Schisandra chinensis, has been reported as an anti-cancer substance. In this study, we investigated the effects of gomisin A on cancer cell proliferation and cell cycle arrest in HeLa cells. Gomisin A significantly inhibited cell proliferation in a dose-dependent manner after 72 h treatment, especially in the presence of tumor necrosis factor-α (TNF-α), due to cell cycle arrest in the G1 phase with the downregulation of cyclin D1 expression and Retinoblastoma (RB) phosphorylation. In addition, gomisin A in combination with TNF-α strongly suppressed the expression of signal transducer and activator of transcription 1 (STAT1). Inhibition of STAT1 pathways by a small-interfering RNA against STAT1 and AG490 Janus kinase (JAK) kinase inhibitor AG490 reduced the cyclin D1 expression and RB phosphorylation, indicating that JAK-mediated STAT1 activation is involved in gomisin A-induced G1 cell cycle arrest.

Toxicity Profiles of Kleeb Bua Daeng Formula, a Traditional Thai Medicine, and Its Protective Effects on Memory Impairment in Animals.

Kleeb Bua Daeng (KBD) formula has long been used in Thailand as a traditional herbal medicine for promoting brain health. Our recent reports illustrated that KBD demonstrates multiple modes of action against several targets in the pathological cascade of Alzheimer's disease (AD). The main purpose of the present study was to determine the protective effect and mechanism of KBD in amyloid beta (Aß)-induced AD rats and its toxicity profiles. Pretreatment with the KBD formula for 14 days significantly improved the short- and long-term memory performance of Aß-induced AD rats as assessed by the Morris Water Maze (MWM) and object-recognition tests. KBD treatment increased the activities of the antioxidant enzymes catalase, superoxide dismutase, and glutathione peroxidase; reduced the malondialdehyde content, and; decreased the acetylcholinesterase activity in the rat brain. An acute toxicity test revealed that the maximum dose of 2000 mg/kg did not cause any mortality or symptoms of toxicity. An oral, subchronic toxicity assessment of KBD at doses of 125, 250, and 500 mg/kg body weight/day for 90 days showed no adverse effects on behavior, mortality, hematology, or serum biochemistry. Our investigations indicate that KBD is a nontoxic traditional medicine with good potential for the prevention and treatment of AD.

Gomisin N enhances TNF-α-induced apoptosis via inhibition of the NF-κB and EGFR survival pathways.

Tumor necrosis factor (TNF-α) is a pleiotropic cytokine that plays an important role in the control of cell proliferation, differentiation, and apoptosis. TNF-α-induced apoptosis is limited by TAK1-mediated activation of NF-κB (mainly p65-p50 hetrodimer) signaling pathway. We have recently reported that TAK1 regulates phosphorylation of EGFR at Ser-1046/7 through p38 MAPK, which cooperates with NF-κB in TNF-α-induced apoptosis. The present study investigated the effect of gomisins A and N, dibenzocyclooctadiene lignans isolated from the fruit of Schisandra chinensis, on TNF-α-induced apoptosis in HeLa cells. Gomisins A and N strongly promoted TNF-α-induced cleavage of caspase-3 and PARP-1, which are key markers of apoptosis. We found that gomisin N, but not gomisin A, inhibited the TNF-α-induced activation of NF-κB by suppressing the activation of IKKα. Gomisin N also inhibited p38-mediated phosphorylation of the EGFR at Ser-1046/7 and subsequent endocytosis of EGFR, another prosurvival pathway. The findings suggested that gomisin N enhanced TNF-α-induced apoptosis by suppressing of NF-κB and EGFR signaling pathways.

Multi-Target Actions of Acridones from Atalantia monophylla towards Alzheimer's Pathogenesis and Their Pharmacokinetic Properties.

Ten acridones isolated from Atalantia monophylla were evaluated for effects on Alzheimer's disease pathogenesis including antioxidant effects, acetylcholinesterase (AChE) inhibition, prevention of beta-amyloid (Aß) aggregation and neuroprotection. To understand the mechanism, the type of AChE inhibition was investigated in vitro and binding interactions between acridones and AChE or Aß were explored in silico. Drug-likeness and ADMET parameters were predicted in silico using SwissADME and pKCSM programs, respectively. All acridones showed favorable drug-likeness and possessed multifunctional activities targeting AChE function, Aß aggregation and oxidation. All acridones inhibited AChE in a mixed-type manner and bound AChE at both catalytic anionic and peripheral anionic sites. In silico analysis showed that acridones interfered with Aß aggregation by interacting at the central hydrophobic core, C-terminal hydrophobic region, and the key residues 41 and 42. Citrusinine II showed potent multifunctional action with the best ADMET profile and could alleviate neuronal cell damage induced by hydrogen peroxide and Aß1-42 toxicity.

Structure-Activity Analysis and Molecular Docking Studies of Coumarins from Toddalia asiatica as Multifunctional Agents for Alzheimer's Disease.

Coumarins, naturally occurring phytochemicals, display a wide spectrum of biological activities by acting on multiple targets. Herein, nine coumarins from the root of Toddalia asiatica were evaluated for activities related to pathogenesis of Alzheimer's disease (AD). They were examined for acetylcholinesterase (AChE) and AChE- or self-induced amyloid beta (Aß) aggregation inhibitory activities, as well as neuroprotection against H2O2- and Aß1-42-induced human neuroblastoma SH-SY5Y cell damage. Moreover, in order to understand the mechanism, the binding interactions between coumarins and their targets: (i) AChE and (ii) Aß1-42 peptide were investigated in silico. All coumarins exhibited mild to moderate AChE and self-induced Aß aggregation inhibitory actions. In addition, the coumarins substituted with the long alkyl chain at position 6 or 8 illustrated ability to inhibit AChE-induced Aß aggregation, resulting from their dual binding site at catalytic anionic site and peripheral active site in AChE. Moreover, the most potent multifunctional coumarin, phellopterin, could attenuate neuronal cell damage induced by H2O2 and Aß1-42 toxicity. Conclusively, seven out of nine coumarins were identified as multifunctional agents inhibiting the pathogenesis of AD. The structure-activity relationship information obtained might be applied for further optimization of coumarins into a useful drug which may combat AD.

Multitarget Activities of Kleeb Bua Daeng, a Thai Traditional Herbal Formula, Against Alzheimer's Disease.

The Kleeb Bua Daeng formula (KBD) is a Thai traditional medicine for brain health promotion. On the basis of the activities of its individual components, the KBD could have good potential for the treatment of Alzheimer's disease (AD). Herein, we investigated the KBD as an AD treatment. The ethanol extracts of KBD and its components, i.e., Nelumbo nucifera (NN), Piper nigrum fruits (BP), and the aerial part of Centella asiatica (CA) exhibited antioxidant activity, as determined by both ABTS and DPPH assays. The Ellman's assay revealed that the KBD, NN, and BP showed an ability to inhibit acetylcholinesterase. The thioflavin T assay indicated that the KBD, NN, BP, and CA inhibited beta-amyloid aggregation. The neuroprotection and Western blot analysis revealed that the KBD reduced H2O2-induced neuronal cell death by inhibiting the expression of pro-apoptotic factors, i.e., cleaved caspase-9 and -3, p-P65, p-JNK, and p-GSK-3ß, as well as by inducing expression of anti-apoptotic factors, i.e., MCl1, BClxl, and survivin. Furthermore, the KBD could improve scopolamine induced memory deficit in mice. Our results illustrate that the KBD with multimode action has the potential to be employed in AD treatment. Thus, the KBD could be used as an alternative novel choice for the prevention and treatment of patients with AD.

Combination of Nimbolide and TNF-α-Increases Human Colon Adenocarcinoma Cell Death through JNK-mediated DR5 Up- regulation.

Tumor necrosis factor (TNF-α), an inflammatory cytokine that plays an important role in the control of cell proliferation, differentiation, and apoptosis, has previously been used in anti-cancer therapy. However, the therapeutic applications of TNF-α are largely limited due to its general toxicity and anti-apoptotic influence. To overcome this problem, the present study focused on the effect of active constituents isolated from a medicinal plant on TNF-α-induced apoptosis in human colon adenocarcinoma (HT-29) cells. Nimbolide from Azadirachta indica was evaluated for cytotoxicity by methyl tetrazolium 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay and phase contrast microscopy. Effects on apoptotic signaling proteins were investigated using Western blot analysis. Nimbolide showed cytotoxicity against HT-29 cells that was significantly different from the control group (<0.01), a concentration of 10 µM significantly inducing cell death (<0.01). In combination with TNF-α, nimbolide significantly enhanced-induced cell death. In apoptotic pathway, nimbolide activated c-Jun N-terminal kinase (JNK) phosphorylation, BH3 interacting-domain death agonist (Bid) and up-regulated the death receptor 5 (DR5) level. In the combination group, nimbolide markedly sensitized TNF-α-induced JNK, Bid, caspase-3 activation and the up-regulation of DR5. Our findings overall indicate that nimbolide may enhance TNF-α-mediated cellular proliferation inhibition through increasing cell apoptosis of HT-29 cells by up-reglation of DR5 expression via the JNK pathway.

Heptaphylline induces apoptosis in human colon adenocarcinoma cells through bid and Akt/NF-κB (p65) pathways.

Heptaphylline derivatives are carbazoles in Clausena harmandiana, a medicinal plant that is utilized for headache, stomach ache, and other treatments of illness. The present study examined the effects of heptaphylline and 7-methoxyheptaphylline on apoptosis of human colon adenocarcinoma cells (HT-29 cell line). Quantification of cell viability was performed using cell proliferation assay (MTT assay) and of protein expression through immunoblotting. The results showed that only heptaphylline, but not 7-methoxyheptaphylline, significantly significantly activated cleaved of caspase-3 and poly (ADP-ribose) polymerase (PARP-1) which resulted in HT-29 cell death. We found that heptaphylline activated BH3 interacting-domain death agonist (Bid) and Bak, proapoptotic proteins. In contrast, it suppressed X-linked inhibitor-of-apoptosis protein (XIAP), Bcl-xL and survivin, inhibitors of apoptosis. In addition, heptaphylline inhibited activation of NF-κB/p65 (rel), a regulator of apoptotic regulating proteins by suppressing the activation of Akt and IKKα, upstream regulators of p65. The findings suggested that heptaphylline induces apoptosis in human colon adenocarcinoma cells .

Synthesis, biological evaluation and molecular modeling study of novel tacrine-carbazole hybrids as potential multifunctional agents for the treatment of Alzheimer's disease.

New tacrine-carbazole hybrids were developed as potential multifunctional anti-Alzheimer agents for their cholinesterase inhibitory and radical scavenging activities. The developed compounds showed high inhibitory activity on acetylcholinesterase (AChE) with IC50 values ranging from 0.48 to 1.03 µM and exhibited good inhibition selectivity against AChE over butyrylcholinesterase (BuChE). Molecular modeling studies revealed that these tacrine-carbazole hybrids interacted simultaneously with the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. The derivatives containing methoxy group showed potent ABTS radical scavenging activity. Considering their neuroprotection, our results indicate that these derivatives can reduce neuronal death induced by oxidative stress and ß-amyloid (Aß). Moreover, S1, the highest potency for both radical scavenging and AChE inhibitory activity, exhibited an ability to improve both short-term and long-term memory deficit in mice induced by scopolamine. Overall, tacrine-carbazole derivatives can be considered as a candidate with potential impact for further pharmacological development in Alzheimer's therapy.

Gomisin N enhances TRAIL-induced apoptosis via reactive oxygen species-mediated up-regulation of death receptors 4 and 5.

Pharmacological studies have revealed that lignans isolated from Schisandra chinensis, including gomisin N, show anticancer, anti-hepatotoxic, anti-oxidative and anti-inflammatory activities. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is an important member of the tumor necrosis factor superfamily with great potential in cancer therapy. The present study investigated whether pretreatment with gomisin N significantly enhanced TRAIL-induced cleavage of caspase-3, caspase-8 and PARP-1, which are key markers of apoptosis. Pretreatment with z-VAD-FMK, a pan-caspase inhibitor, was able to inhibit apoptosis enhanced by the combination of gomisin N and TRAIL. These results suggested that gomisin N could promote TRAIL-induced apoptosis through the caspase cascade. In search of the molecular mechanisms, we elucidated that such enhancement was achieved through transcriptional up-regulation of TRAIL receptors, death receptor 4 (DR4) and DR5. Neutralization of DR4 and DR5 could significantly reduce apoptosis induced by gomisin N and TRAIL. We also revealed that gomisin N increased the generation of reactive oxygen species (ROS). N-acetyl cysteine (NAC), an antioxidant, could inhibit ROS production and up-regulation of DR4 and DR5. Overall, our results indicated that gomisin N was able to potentiate TRAIL-induced apoptosis through ROS-mediated up-regulation of DR4 and DR5.

Bufotalin sensitizes death receptor-induced apoptosis via Bid- and STAT1-dependent pathways.

Tumor necrosis factor-alpha (TNF-α) and TNF-related apoptosis-inducing ligand (TRAIL) are apoptosis-inducing ligands that stimulate death receptors. In this study, we investigated the effects of bufotalin, a major compound in toad venom, on sensitizing TNF-α and TRAIL-induced apoptosis of HeLa cells. Bufotalin promoted death receptor-mediated cell death, especially TRAIL-induced apoptosis, through activation of caspase-3 and PARP-1. Mitochondrial Bid-dependent pathway was activated in TNF-α-induced cell death. Cotreatment of bufotalin with TRAIL resulted in the downregulation of anti-apoptotic proteins, including Bcl-XL, Mcl-1, survivin and XIAP, and the up-regulation of MAPKs and TRAIL receptor DR5. In addition, phosphorylation of STAT1 was strongly inhibited by bufotalin. Moreover, DR5 expression was induced by knocking down the STAT1 expression. Moreover, the TRAIL-induced apoptotic response was promoted by STAT1 siRNA. Our results demonstrated that bufotalin is a powerful sensitizer of death receptor-induced apoptosis in cancer cells.

Artesunate enhances TRAIL-induced apoptosis in human cervical carcinoma cells through inhibition of the NF-κB and PI3K/Akt signaling pathways.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) selectively induces apoptosis and kills cancer cells with little or no adverse effects on normal cells. TRAIL is relatively safe for clinical applications. However, TRAIL resistance is widely found in cancer cells leading to limitations in utilizing TRAIL as a therapeutic agent for cancer treatment. Recently, artesunate, an effective and safe anti-malarial drug, was also described as a promising candidate for cancer therapy. It would be of importance to determine whether combination treatment of TRAIL together with artesunate could overcome drug-resistance of tumors. Here, we demonstrate the first evidence that artesunate effectively enhances TRAIL-mediated cytotoxicity by suppressing pro-survival proteins, such as survivin, XIAP and Bcl-XL. Upon treatment with artesunate, the levels of survival proteins were strongly suppressed in HeLa cells. The down-regulation of these survival proteins could be regulated by repressing activation of NF-κB and Akt. Artesunate also inhibited TRAIL-induced transcriptional activity of NF-κB. In addition, this substance significantly enhanced both extrinsic and intrinsic apoptosis, which were induced by TRAIL. Taken together, the results of the present study suggest that artesunate exhibits an ability to overcome TRAIL resistance and combination treatment of TRAIL together with artesunate may be an effective strategy for cancer therapy.