Aponermin: First Approval

Aponermin () is a recombinant circularly permuted human tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) developed by Beijing Sunbio Biotech (a wholly owned subsidiary of Wuhan Hiteck Biological Pharma CO., LTD) for the treatment of multiple myeloma. Aponermin binds to and activates the death receptors 4 and/or 5 on tumour cells, triggering intracellular caspase reactions and inducing apoptosis, thereby exerting antitumor effects. In November 2023, aponermin in combination with thalidomide and dexamethasone received its first approval in China for the treatment of patients with relapsed or refractory multiple myeloma who have received at least two prior therapies. This article summarizes the milestones in the development of aponermin leading to this first approval for relapsed or refractory multiple myeloma.

Significance of TRAIL/Apo-2 ligand and its death receptors in apoptosis and necroptosis signalling: Implications for cancer-targeted therapeutics

The human immune defensesystem routinely expresses the tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), which is the most prevalent element for antitumor immunity. TRAIL associates with its death receptors (DRs), DR4 (TRAIL-R1), and DR5 (TRAIL-R2), in cancer cells to initiate the intracellular apoptosis cascade. Accordingly, numerous academic institutions and pharmaceutical companies havetried to exploreTRAIL's capacity to kill tumourcells by producing recombinant versions of it (rhTRAIL) or TRAIL receptor agonists (TRAs) [monoclonal antibody (mAb), synthetic and natural compounds, etc.] and molecules that sensitize TRAIL signalling pathway for therapeutic applications. Recently, several microRNAs (miRs) have been found to activate or inhibit death receptor signalling. Therefore, pharmacological regulation of these miRs may activate or resensitize the TRAIL DRs signal, and this is a novel approach for developing anticancer therapeutics. In this article, we will discuss TRAIL and its receptors and molecular pathways by which it induces various cell death events. We will unravel potential innovative applications of TRAIL-based therapeutics, and other investigated therapeutics targeting TRAIL-DRs and summarize the current preclinical pharmacological studies and clinical trials. Moreover, we will also emphasizea few situations where future efforts may be addressed to modulate the TRAIL signalling pathway.

Proteome and phosphoproteome profiling of non-small cell lung cancer cell line A549 treated with TRAIL

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is recognized for its promising therapeutic effects against cancer. However, mechanisms underlying the effect of TRAIL on protein expression, signal transduction, and apoptosis induction remain unclear. We surmised that a systematic analysis of the proteome and phosphoproteome associated with TRAIL signaling may help elucidate the mechanisms involved and facilitate the development of therapeutics. Therefore, we investigated the proteome and phosphoproteome of non-small cell lung cancer cell line A549 treated with TRAIL. Our results indicated that 126 proteins and 1684 phosphosites were markedly differentially expressed between the phosphate-buffered saline- and TRAIL-treated groups. The expression at protein and phosphosite levels were not completely consistent. Gene ontology functional analysis revealed that metal ion (zinc) binding was highly affected by TRAIL treatment. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that almost all pathways that involved differentially expressed phosphosites were associated with apoptosis. We also identified an important kinase, AKT1, and its series of substrates in TRAIL signaling. The results of this study may provide guidance for future research on tumor therapy using TRAIL.

Harnessing TRAIL-induced cell death for cancer therapy: a long walk with thrilling discoveries

Tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL) can induce apoptosis in a wide variety of cancer cells, both in vitro and in vivo, importantly without killing any essential normal cells. These findings formed the basis for the development of TRAIL-receptor agonists (TRAs) for cancer therapy. However, clinical trials conducted with different types of TRAs have, thus far, afforded only limited therapeutic benefit, as either the respectively chosen agonist showed insufficient anticancer activity or signs of toxicity, or the right TRAIL-comprising combination therapy was not employed. Therefore, in this review we will discuss molecular determinants of TRAIL resistance, the most promising TRAIL-sensitizing agents discovered to date and, importantly, whether any of these could also prove therapeutically efficacious upon cancer relapse following conventional first-line therapies. We will also discuss the more recent progress made with regards to the clinical development of highly active non-immunogenic next generation TRAs. Based thereupon, we next propose how TRAIL resistance might be successfully overcome, leading to the possible future development of highly potent, cancer-selective combination therapies that are based on our current understanding of biology TRAIL-induced cell death. It is possible that such therapies may offer the opportunity to tackle one of the major current obstacles to effective cancer therapy, namely overcoming chemo- and/or targeted-therapy resistance. Even if this were achievable only for certain types of therapy resistance and only for particular types of cancer, this would be a significant and meaningful achievement.

Improving Targeted Delivery and Antitumor Efficacy with Engineered Tumor Necrosis Factor-Related Apoptosis Ligand-Affibody Fusion Protein

Tumor necrosis factor-related apoptosis ligand (TRAIL) is a promising protein candidate for selective apoptosis of a variety of cancer cells. However, the short half-life and a lack of targeted delivery are major obstacles for its application in cancer therapy. Here, we propose a simple strategy to solve the targeting problem by genetically fusing an anti-HER2 affibody to the C-terminus of the TRAIL. The fusion protein TRAIL-affibody was produced as a soluble form with high yield in recombinant Escherichia coli. In vitro studies proved that the affibody domain promoted the cellular uptake of the fusion protein in the HER2 overexpressed SKOV-3 cells and improved its apoptosis-inducing ability. In addition, the fusion protein exhibited higher accumulation at the tumor site and greater antitumor effect than those of TRAIL in vivo, indicating that the affibody promoted the tumor homing of the TRAIL and then improved the therapeutic efficacy. Importantly, repeated injection of high-dose TRAIL-affibody showed no obvious toxicity in mice. These results demonstrated that the engineered TRAIL-affibody is promising to be a highly tumor-specific and targeted cancer therapeutic agent.

TRAIL of Hope Meeting Resistance in Cancer

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) induces apoptosis selectively via its interaction with the death receptors TRAILR1/DR4 and TRAILR2/DR5 in a wide range of cancers, while sparing normal cells. Despite its tremendous potential for cancer therapeutics, the translation of TRAIL into the clinic has been confounded by TRAIL-resistant cancer populations. We discuss different molecular mechanisms underlying TRAIL-mediated apoptosis and resistance to TRAIL. We also discuss the successes and failures of recent preclinical and clinical studies of TRAIL-induced apoptosis, and current attempts to overcome TRAIL resistance, and we provide a perspective for improving the prospects of future clinical implementation.

Glutathione-Specific and Intracellularly Labile Polymeric Nanocarrier for Efficient and Safe Cancer Gene Delivery

Cationic polymers condense nucleic acids into nanosized complexes (polyplexes) that are widely explored for nonviral gene delivery, but their strong electrostatic binding with DNA causes inefficient intracellular gene release and translation and thereby unsatisfactory gene transfection efficiencies. Facilitated intracellular dissociation of polyplexes by making the polymer undergo positive-to-negative/neutral charge reversal can effectively solve these problems, but they must be sufficiently stable during the delivery. Herein, we report the first glutathione (GSH)-specific intracellular labile polyplexes for cancer-targeted gene delivery. The polymers are made from p-(2,4-dinitrophenyloxybenzyl)-ammonium cationic moieties, whose p-2,4-dinitrophenyl ether is cleaved specifically by GSH, rather than other biological thiols, triggering the conversion of the ammonium cation into the carboxylate anion and thus the fast intracellular DNA release of the polyplexes. Furthermore, the polyplexes coated with PEG-functionalized lipids are stable in biological fluids to gain long blood circulation for tumor accumulation. Thus, the efficient tumor accumulation and cell transfection of the polyplexes loaded with the tumor suicide gene tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) give rise to potent antitumor activity similar to that of the first-line chemotherapy drug paclitaxel but with much less adverse effects.

MADD silencing enhances anti-tumor activity of TRAIL in anaplastic thyroid cancer

ATC is an aggressive disease with limited therapeutic options due to drug resistance. TRAIL is an attractive anti-cancer therapy that can trigger apoptosis in a cancer cell-selective manner. However, TRAIL resistance is a major clinical obstacle for its use as a therapeutic drug. Previously, we demonstrated that MADD is a cancer cell pro-survival factor that can modulate TRAIL resistance. However, its role, if any, in overcoming TRAIL resistance in ATC is unknown. First, we characterized ATC cell lines as either TRAIL resistant, TRAIL sensitive or moderately TRAIL sensitive and evaluated MADD expression/cellular localization. We determined the effect of MADD siRNA on cellular growth and investigated its effect on TRAIL treatment. We assessed the effect of combination treatment (MADD siRNA and TRAIL) on mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) levels. The effect of combination treatment on tumor growth was assessed in vivo. We found increased levels of MADD in ATC cells relative to Nthy-ori 3-1. MADD protein localizes in the cytosol (endoplasmic reticulum and Golgi body) and membrane. MADD knockdown resulted in spontaneous cell death that was synergistically enhanced when combined with TRAIL treatment in otherwise resistant ATC cells. Combination treatment resulted in a significant reduction in MMP and enhanced generation of ROS indicating the putative mechanism of action. In an orthotopic mouse model of TRAIL-resistant ATC, treatment with MADD siRNA alone reduced tumor growth that, when combined with TRAIL, resulted in significant tumor regressions. We demonstrated the potential clinical utility of MADD knockdown in sensitizing cells to TRAIL-induced apoptosis in ATC.

Attenuation of autophagy flux by 6-shogaol sensitizes human liver cancer cells to TRAIL-induced apoptosis via p53 and ROS

Tumor necrosis factor (TNF)‑related apoptosis‑inducing ligand (TRAIL) is a member of the TNF superfamily and is an antitumor drug that induces apoptosis in tumor cells with minimal or no effects on normal cells. Here, it is demonstrated that 6‑shogaol (6‑sho), a bioactive component of ginger, exerted anti‑inflammatory and anticancer properties, attenuated tumor cell propagation and induced TRAIL‑mediated cell death in liver cancer cells. The current study identified a potential pathway by revealing that TRAIL and 6‑sho or chloroquine acted together to trigger reactive oxygen species (ROS) production, to upregulate tumor‑suppressor protein 53 (p53) expression and to change the mitochondrial transmembrane potential (MTP). Treatment with N‑acetyl‑L‑cysteine reversed these effects, restoring the MTP and attenuated ROS production and p53 expression. Interestingly, treatment with 6‑sho increased p62 and microtubule‑associated proteins 1A/1B light chain 3B‑II levels, indicating an inhibited autophagy flux. In conclusion, attenuation of 6‑sho‑induced autophagy flux sensitized cells to TRAIL‑induced apoptosis via p53 and ROS, suggesting that the administration of TRAIL in combination with 6‑sho may be a suitable therapeutic method for the treatment of TRAIL‑resistant Huh7 liver cells.

Concise Review: Neural Stem Cell-Mediated Targeted Cancer Therapies

Cancer is one of the leading causes of morbidity and mortality worldwide, with 1,688,780 new cancer cases and 600,920 cancer deaths projected to occur in 2017 in the U.S. alone. Conventional cancer treatments including surgical, chemo-, and radiation therapies can be effective, but are often limited by tumor invasion, off-target toxicities, and acquired resistance. To improve clinical outcomes and decrease toxic side effects, more targeted, tumor-specific therapies are being developed. Delivering anticancer payloads using tumor-tropic cells can greatly increase therapeutic distribution to tumor sites, while sparing non-tumor tissues therefore minimizing toxic side effects. Neural stem cells (NSCs) are tumor-tropic cells that can pass through normal organs quickly, localize to invasive and metastatic tumor foci throughout the body, and cross the blood-brain barrier to reach tumors in the brain. This review focuses on the potential use of NSCs as vehicles to deliver various anticancer payloads selectively to tumor sites. The use of NSCs in cancer treatment has been studied most extensively in the brain, but the findings are applicable to other metastatic solid tumors, which will be described in this review. Strategies include NSC-mediated enzyme/prodrug gene therapy, oncolytic virotherapy, and delivery of antibodies, nanoparticles, and extracellular vesicles containing oligonucleotides. Preclinical discovery and translational studies, as well as early clinical trials, will be discussed. Stem Cells Translational Medicine 2018;7:740-747.

TRAIL mutant membrane penetrating peptide alike-MuR6-TR enhances the antitumor effects of TRAIL in pancreatic carcinoma both in vitro and in vivo

To remedy the drug resistance of natural tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and enhance its antitumor effects, we prepared a type of TRAIL mutant membrane penetrating peptide alike (TMPPA)‑TRAIL mutant R6 (MuR6-TR) by mutating the N‑terminal of the soluble TRAIL gene sequence. The expressed MuR6‑TR protein was purified to treat pancreatic carcinoma cell lines BxPC‑3 and PANC‑1. The inhibitory effects on the proliferation of BxPC‑3 and PANC‑1 cells was assessed with CCK‑8 assay and compared with natural TRAIL. The antitumor effect of MuR6‑TR was assessed on implant tumors derived from PANC‑1 cells in nude mice and compared with gemcitabine. Finally, the soluble MuR6‑TR gene was successfully mutated with 4 amino acids in the N‑terminal of TRAIL and had a molecular size of 513 bp. The mutant MuR6‑TR was connected to pET32a and verified by enzymatic digestion and sequencing. The recombinant MuR6‑TR was transformed and expressed in Escherichia coli. The CCK‑8 assay results indicated that MuR6‑TR inhibited the growth of BxPC‑3 and PANC‑1 cells in a dose‑dependent manner, with IC50 values of 4.63 and 7.84 ng/ml, respectively, which were much lower than that of natural TRAIL. MuR6‑TR demonstrated a higher inhibitory effect on tumor growth (24.2%) than natural TRAIL (14.4%) and an effect similar to that of gemcitabine at an early period. Thus, the mutant MuR6‑TR exhibited a stronger antitumor effect than that of natural TRAIL both in vivo and in vitro and may have potential therapeutic value for pancreatic carcinoma, which requires further validation.

Inhibition of NF-κB Pathway and Modulation of MAPK Signaling Pathways in Glioblastoma and Implications for Lovastatin and Tumor Necrosis Factor-Related Apoptosis Inducing Ligand (TRAIL) Combination Therapy

Glioblastoma is a common malignant brain tumor and it is refractory to therapy because it usually contains a mixture of cell types. The tumor necrosis factor-related apoptosis inducing ligand (TRAIL) has been shown to induce apoptosis in a range of tumor cell types. Previously, we found that two human glioblastoma cell lines are resistant to TRAIL, while lovastatin sensitizes these glioblastoma cells to TRAIL-induced cell death. In this study, we investigated the mechanisms underlying the TRAIL-induced apoptosis in human glioblastoma cell lines by lovastatin. Furthermore, we have confirmed the anti-tumor effect of combination therapy with lovastatin and TRAIL in the subcutaneous brain tumor model. We showed that lovastatin significantly up-regulated the expression of death receptor 5 (DR5) in glioblastoma cell lines as well as in tumor-bearing mice with peri-tumoral administration of lovastatin. Further study in glioblastoma cell lines suggested that lovastatin treatment could inhibit NF-κB and Erk/MAPK pathways but activates JNK pathway. These results suggest that lovastatin sensitizes TRAIL-induced apoptosis by up-regulation of DR5 level via NF-κB inactivation, but also directly induces apoptosis by dysregulation of MAPK pathway. Our in vivo study showed that local peri-tumoral co-injection of lovastatin and TRAIL substantially reduced tumor growth compared with single injection of lovastatin or TRAIL in subcutaneous nude mice model. This study suggests that combined treatment of lovastatin and TRAIL is a promising therapeutic strategy to TRAIL-resistant glioblastoma.

The promise of circulating tumor cells for precision cancer therapy

The rapidly growing array of therapeutic options in cancer requires informative biomarkers to guide the rational selection and precision application of appropriate therapies. Circulating biomarkers such as circulating tumor cells have immense potential as noninvasive, serial 'liquid biopsies' that may be more representative of the complete spectrum of a patient's individual malignancy than spatially and temporally restricted tumor biopsies. In this review, we discuss the current state-of-the-art in the isolation and molecular characterization of circulating tumor cells as well as their utility in a wide range of clinical applications such as prognostics, treatment monitoring and identification of novel therapeutic targets and resistance mechanisms to enable real-time adjustments in the clinical management of cancer.

Titanium wire implants with nanotube arrays: A study model for localized cancer treatment

Adverse complications associated with systemic administration of anti-cancer drugs are a major problem in cancer therapy in current clinical practice. To increase effectiveness and reduce side effects, localized drug delivery to tumour sites requiring therapy is essential. Direct delivery of potent anti-cancer drugs locally to the cancer site based on nanotechnology has been recognised as a promising alternative approach. Previously, we reported the design and fabrication of nano-engineered 3D titanium wire based implants with titania (TiO2) nanotube arrays (Ti-TNTs) for applications such as bone integration by using in-vitro culture systems. The aim of present study is to demonstrate the feasibility of using such Ti-TNTs loaded with anti-cancer agent for localized cancer therapy using pre-clinical cancer models and to test local drug delivery efficiency and anti-tumour efficacy within the tumour environment. TNF-related apoptosis-inducing ligand (TRAIL) which has proven anti-cancer properties was selected as the model drug for therapeutic delivery by Ti-TNTs. Our in-vitro 2D and 3D cell culture studies demonstrated a significant decrease in breast cancer cell viability upon incubation with TRAIL loaded Ti-TNT implants (TRAIL-TNTs). Subcutaneous tumour xenografts were established to test TRAIL-TNTs implant performance in the tumour environment by monitoring the changes in tumour burden over a selected time course. TRAIL-TNTs showed a significant regression in tumour burden within the first three days of implant insertion at the tumour site. Based on current experimental findings these Ti-TNTs wire implants have shown promising capacity to load and deliver anti-cancer agents maintaining their efficacy for cancer treatment.

Novel Molecular Regulators of Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL)-Induced Apoptosis in NSCLC Cells

BACKGROUND

Although tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can selectively induce apoptosis in some non-small cell lung cancer (NSCLC) cells, some NSCLC cells exhibit TRAIL-resistance. The underlying mechanisms that regulate TRAIL sensitivity in NSCLC cells are not well understood. The objective of this study was to investigate molecular regulators of the TRAIL pathway in NSCLC cells.

METHODS

The TRAIL-sensitive NSCLC cell line NCI-H358 and a TRAIL-resistant cell line A549 were treated with rmhTRAIL for 24 hours. Then cell viability were measured by MTT assay, meanwhile cell cycle and apoptosis were measured by flow cytometry. Furthermore, mass spectrometry (LC-MS/MS) was used to identify the difference in the protein expression profiles. Finally, real-time PCR was performed to detect the mRNA expression of TRAIL receptors and apoptotic related proteins.

RESULTS

These results confirmed that NCI-H358 cells were sensitive to TRAIL, whereas A549 cells were resistant. Both mRNA and protein levels of voltage-dependent anion-selective channel proteinl (VDAC1), caspase9 (CASP9), and cytochrome c1 (CYC1) were upregulated in H358 cells but downregulated in A549 cells, whereas antiapoptotic protein BAG-2 was downregulated. In addition, TRAIL also causes DR5 low expression in A549 cells.

CONCLUSIONS

These results indicate that rmhTRAIL had different anti-tumor activity in different NSCLC cell lines. Downregulation of VDAC1, CYC1, CASP9, and upregulation of BAG-2 might be associated with underlying TRAIL-resistance mechanisms. These findings motivated further studies to explore new therapeutic strategy overcoming TRAIL-resistance of NSCLC cells through modulating dysregulation of the proteins above.

TRAIL-coated leukocytes that prevent the bloodborne metastasis of prostate cancer

Prostate cancer, once it has progressed from its local to metastatic form, is a disease with poor prognosis and limited treatment options. Here we demonstrate an approach using nanoscale liposomes conjugated with E-selectin adhesion protein and Apo2L/TRAIL (TNF-related apoptosis-inducing ligand) apoptosis ligand that attach to the surface of leukocytes and rapidly clear viable cancer cells from circulating blood in the living mouse. For the first time, it is shown that such an approach can be used to prevent the spontaneous formation and growth of metastatic tumors in an orthotopic xenograft model of prostate cancer, by greatly reducing the number of circulating tumor cells. We conclude that the use of circulating leukocytes as a carrier for the anti-cancer protein TRAIL could be an effective tool to directly target circulating tumor cells for the prevention of prostate cancer metastasis, and potentially other cancers that spread through the bloodstream.

TRAIL and targeting cancer cells: between promises and obstacles

Targeting cancer cells is one of the challenges of current treatment strategies. TRAIL represents a promising therapeutic approach and over the past decades there was an increased interest in targeting TRAIL signaling to treat cancer. Indeed, TRAIL can specifically target cancer cells and exhibits very low cytotoxicity towards normal cells. However, rapidly accumulating experimental evidence has started to shed light on multiple factors which induce resistance against TRAIL in cancer cells. This resistance consists of various mechanisms including downregulation of death receptors and caspase-8 and overexpression of decoy receptors as well as antiapoptotic factors such as members of Bcl-2 family. Even if several studies focused on elucidating those resistance mechanisms, there still remain gray areas that need to be fully elucidated. Thus, therapeutic approaches could consist of targeting both resistance signaling pathways and TRAIL signaling to enhance TRAIL therapy efficiency.

A time to kill: targeting apoptosis in cancer

The process of apoptosis is essential for maintaining the physiologic balance between cell death and cell growth. This complex process is executed by two major pathways that participate in activating an executioner mechanism leading to chromatin disintegration and nuclear fragmentation. Dysregulation of these pathways often contributes to cancer development and resistance to cancer therapy. Here, we review the most recent discoveries in apoptosis regulation and possible mechanisms for resensitizing tumor cells to therapy.

Combination of arginine deprivation with TRAIL treatment as a targeted-therapy for mesothelioma

In the present study we present data to show that certain tumor cells including malignant pleural mesothelioma (MPM) cells do not express argininosuccinate synthetase (ASS), and thus are unable to synthesize arginine from citrulline. Exposure of these ASS-negative cells to the arginine degrading enzyme, arginine deiminase (ADI-PEG20), for 72 h results in significant increases in cleaved caspase-3. Importantly, this apoptotic signal is further strengthened by the addition of TNF-related apoptosis-inducing ligand (TRAIL). Using flow cytometry, we showed that the combination treatment (ADI-PEG20 at 50 ng/ml and TRAIL at 10 ng/ml) for 24 h resulted in profound cell death with 67% of cells positive for caspase-3 activity, while ADI-PEG20 alone or TRAIL alone resulted in only 10-15% cell death. This positive amplification loop is mediated through the cleavage of proapototic protein "BID".

CONCLUSION

Our work represents a new strategy for treating patients with malignant pleural mesothelioma using targeted molecular therapeutics based on selected tumor markers, thus avoiding the use of potentially cytotoxic chemotherapy.

Photochemically mediated delivery of AdhCMV-TRAIL augments the TRAIL-induced apoptosis in colorectal cancer cell lines

Tumor targeting is an important issue in cancer gene therapy. We have developed a light-specific transduction method, named photochemical internalization (PCI), to enhance gene expression from adenoviral vectors selectively in illuminated areas. Tumor necrosis factor related apoptosis inducing ligand (TRAIL) has been shown to induce apoptosis in cancer cells, and the aim of this study was to investigate the potential of PCI to enhance transgene expression from AdhCMV-TRAIL and evaluate its impact on apoptotic induction in the two human colorectal cancer cell lines HCT116 and WiDr. PCI-mediated delivery of AdhCMV-TRAIL enabled an increased expression of TRAIL, induced a synergistic reduction in cell viability compared to the individual action of AdhCMV-TRAIL and photochemical treatment, and enhanced the induction of apoptosis demonstrated by an increase in cytoplasmic histone-associated DNA fragments, caspase-8 and caspase-3 activation, PARP cleavage and a decrease in the mitochondrial membrane potential. The synergistic effect could be related to the enhanced TRAIL expression in PCI-treated samples and a modest sensitization of the cancer cells to TRAIL induced apoptosis due to the photochemical treatment. Furthermore, an increased cleavage of Bid and a cell line dependent reduction in the expression levels of anti-apoptotic Bcl-2 family members were observed and could possibly contribute to the enhanced apoptotic level in samples exposed to the combined treatment. The presented results indicate that photochemically mediated delivery of AdhCMV-TRAIL allows a selective enhancement in cell killing, and suggest that PCI may be relevant and advantageous for therapeutic gene delivery in vivo.

Riproximin's activity depends on gene expression and sensitizes PDAC cells to TRAIL

Riproximin (Rpx) is a type II ribosome inactivating protein, which was investigated for its activity in pancreatic ductal adenocarcinoma (PDAC) in a panel of 17 human and rat PDAC cell lines and in rat pancreatic cancer liver metastasis. Cytotoxicity in response to Rpx was determined by MTT assay, apoptosis by flow cytometry and qRT-PCR for apoptosis related genes, and the modulation of the transcriptome was monitored by micro array analysis. The combination effect of Rpx and TRAIL was assessed by MTT assay. Rpx showed high but varying cytotoxicity in PDAC cells. Based on overall gene expression, the sensitivity of these cells was linked to genes involved in apoptosis. Furthermore, based on the affinity of Rpx for CEA, the expression of carcinoembryonic antigen-related cell adhesion molecule (CEACAM) genes was significantly related to Rpx's cytotoxicity in cells with CEACAM gene expression. Exposure of Suit2-007 cells to Rpx induced the mRNA expression of members of signaling pathways initiating from most death receptors, and down modulation of TRAIL. Apoptosis was increased as shown by FACS analysis. Combination of Rpx with TRAIL resulted in a synergistic cytotoxic effect in human Suit2-007 and rat ASML cells, as evidenced by a 6-fold lower tumor cell survival than expected from an additive combination effect. Treatment of BDX rats bearing intra-portally implanted Suit2-007 cells showed a highly significant anticancer effect and indicated an application of Rpx against pancreatic cancer metastasis to the liver. These data favor further evaluation of Rpx as anticancer agent in PDAC.

Magnetic iron oxide nanoparticles mediated gene therapy for breast cancer--an in vitro study

The aim of this study was to evaluate the feasibility and efficacy of using TRAIL gene to treat breast cancer mediated with a novel carrier - magnetic iron oxide nanoparticles (poly-MAG-1000) coated with PEI. The magnetic iron oxide nanoparticles were used as gene carrier to transfect TRAIL gene into MCF-7 cells. The polyMAG-1000 without TRAIL gene was transfected into the tumor cells as negative control. TRAIL gene transfection with liposome as carrier served as positive control. The apoptosis of cells was detected with TUNEL method. The apoptosis ratio of tumor cells was measured with flow cytometry (FCM). It was found that the apoptosis occurred in the tumor cells after transfection of TRAIL gene mediated by both polyMAG-1000 and liposome. The apoptosis ratio in the group with polyMAG-1000 as gene carrier was (25.11+/-2.85) %, whereas it was (5.06+/- 1.05) % in the control group with polyMAG-1000 (P<0.01). The apoptosis ratio was as low as (18.31+/-2.44) % in the group with liposome as gene carrier (P<0.05, as compared with the group with polyMAG-1000 as gene carrier). It is suggested that TRAIL gene may induce apoptosis in MCF-7 breast cancer cells. The magnetic iron oxide nanoparticles coated with PEI may be a potential gene carrier with high transfection efficacy for cancer gene therapy..

TRAIL on trial: preclinical advances in cancer therapy

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand, or TRAIL, is a promising anticancer agent as it can induce apoptosis in a wide range of cancers whilst generally sparing non-malignant cells. However, the translation of TRAIL into the clinic has been confounded by its short half-life, inadequate delivery methods, and TRAIL-resistant cancer cell populations. In this review, we discuss how TRAIL has been functionalized to diversify its traditional tumor-killing role and novel strategies to facilitate its effective deployment in preclinical cancer models. The successes and failures of the most recent clinical trials using TRAIL agonists are highlighted and we provide a perspective for improving its clinical implementation.

Death receptors as targets in cancer

Anti-tumour therapies based on the use pro-apoptotic receptor agonists, including TNF-related apoptosis-inducing ligand (TRAIL) or monoclonal antibodies targeting TRAIL-R1 or TRAIL-R2, have been disappointing so far, despite clear evidence of clinical activity and lack of adverse events for the vast majority of these compounds, whether combined or not with conventional or targeted anti-cancer therapies. This brief review aims at discussing the possible reasons for the lack of apparent success of these therapeutic approaches and at providing hints in order to rationally design optimal protocols based on our current understanding of TRAIL signalling regulation or resistance for future clinical trials.

LINKED ARTICLES

This article is part of a themed section on Emerging Therapeutic Aspects in Oncology. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.169.issue-8.

Making personalized prostate cancer medicine a reality: challenges and opportunities in the re-establishment of gold standards

Prostate cancer is a serious multidimensional disorder that arises because of misrepresentation of signaling cascades and acquired resistance against apoptosis. It is progressively becoming more insurmountable because of rheostat like switching of oncogenic signaling in androgen dependent and androgen depleted microenvironment. Additionally, oncogenic fusion proteins have been explored in prostate cancer tissues thus adding another layer of complexity to the targeting of protein network in cancer cell and generate hurdles in the standardization of therapy. In this Review we briefly describe identified oncogenic fusion transcripts in prostate cancer and suggest utilization of this biomarker for prostate cancer diagnosis alongwith standard PSA and immunohistochemistry analysis in Pakistan. We also provide overview of animal model studies to interpret the efficacy of vitamins.

The TRAIL of oncogenes to apoptosis

Despite the significant advances in clinical research, surgical resection, radiotherapy and chemotherapy are still used as the primary method for cancer treatment. As compared to conventional therapies that often induce systemic toxicity and eventually contribute to tumor resistance, the TNF-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent that selectively triggers apoptosis in various cancer cells by interacting with its proapoptotic receptors DR4 and KILLER/DR5, while sparing the normal surrounding tissue. The intensive studies of TRAIL signaling pathways over the past decade have provided clues for understanding the molecular mechanisms of TRAIL-induced apoptosis in carcinogenesis and identified an array of therapeutic responses elicited by TRAIL and its receptor agonists. Analysis of its activity at the molecular level has shown that TRAIL improves survival either as monotherapies or combinatorial therapies with other mediators of apoptosis or anticancer chemotherapy. Combinatorial treatments amplify the activities of anticancer agents and widen the therapeutic window by overcoming tumor resistance to apoptosis and driving cancer cells to self-destruction. Although TRAIL sensitivity varies widely depending on the cell type, nontransformed cells are largely resistant to death mediated by TRAIL Death Receptors (DRs). Genetic alterations in cancer can contribute in tumor progression and often play an important role in evasion of apoptosis by tumor cells. Remarkably, RAS, MYC and HER2 oncogenes have been shown to sensitise tumor cells to TRAIL induced cell death. Here, we summarise the cross-talk of oncogenic and apoptotic pathways and how they can be exploited toward efficient combinatorial therapeutic protocols.

On the TRAIL to successful cancer therapy? Predicting and counteracting resistance against TRAIL-based therapeutics

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and agonistic antibodies against TRAIL death receptors (DR) kill tumor cells while causing virtually no damage to normal cells. Several novel drugs targeting TRAIL receptors are currently in clinical trials. However, TRAIL resistance is a common obstacle in TRAIL-based therapy and limits the efficiency of these drugs. In this review article we discuss different mechanisms of TRAIL resistance, and how they can be predicted and therapeutically circumvented. In addition, we provide a brief overview of all TRAIL-based clinical trials conducted so far. It is apparent that although the effects of TRAIL therapy are disappointingly modest overall, a small subset of patients responds very well to TRAIL. We argue that the true potential of targeting TRAIL DRs in cancer can only be reached when we find efficient ways to select for those patients that are most likely to benefit from the treatment. To achieve this, it is crucial to identify biomarkers that can help us predict TRAIL sensitivity.

Targeting the apoptotic pathway in chondrosarcoma using recombinant human Apo2L/TRAIL (dulanermin), a dual proapoptotic receptor (DR4/DR5) agonist

Recombinant human Apo2L/TRAIL (dulanermin) is based on the ligand for death receptors (DR4 and DR5), which promotes apoptosis. We report a patient with refractory chondrosarcoma who showed a prolonged response to dulanermin and explore mechanisms of response and resistance. This heavily pretreated patient had progressive metastatic chondrosarcoma to the lung. On dulanermin (8 mg/kg i.v. on days 1-5 in a 21-day cycle), the patient achieved a sustained partial response with only subcentimeter nodules remaining. After 62 months of dulanermin treatment, progressive disease in the lungs was noted, and the patient underwent a resection that confirmed chondrosarcoma. DR4 was detected (immunohistochemistry) in the patient's tumor, which may have enabled the response. However, upregulation of prosurvival proteins, namely, phosphorylated (p)-NF-κBp65 (Ser 536), p-STAT3 (Tyr 705), p-ERK 1/2 (Thr 202/Tyr 204), p-mTOR (Ser 2448), FASN, and Bcl-2, were also detected, which may have provided the underlying mechanisms for acquired dulanermin resistance. The patient was restarted on dulanermin and has continued on this treatment for an additional 16 months since surgery (78 months since initiation of treatment), with his most recent computed tomography (CT) scans showing no evidence of disease.

Synergistic antitumor effect of TRAIL and IL-24 with complete eradication of hepatoma in the CTGVT-DG strategy

The ZD55-tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and ZD55-interleukin (IL)-24 were constructed by inserting TRAIL or IL-24 gene separately into the oncolytic adenovirus named ZD55 (with adenovirus E1B-55kD deletion). The resulting ZD55-TRAIL and ZD55-IL-24 were used in combination to treat xenograft tumors in nude mice model. The results showed that it can not only completely eliminate BEL7404 hepatoma xenograft but also have excellent antitumor effect against gaster, lung, prostate, and breast carcinomas. It was also found that ZD55-TRAIL could not only suppress the tumor growth promoting effect by ZD55-IL-24 at lower dosage, but also substantially reduce the cancer cell viability in their combined use. This is because ZD55-IL-24 and ZD55-TRAIL could mutually enhance each other's antitumor effect greatly. All these findings conspicuously showed the synergistic antitumor effect of TRAIL and IL-24, which is also the reason for the antitumor effect by the combined use of TRAIL and IL-24 in vitro and also in vivo.

Targeting tumour-initiating cells with TRAIL based combination therapy ensures complete and lasting eradication of multiple myeloma tumours in vivo

Multiple myeloma (MM) remains an incurable disease despite improvements to available treatments and efforts to identify new drug targets. Consequently new approaches are urgently required. We have investigated the potential of native tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), in combination with doxorubicin, to induce apoptotic cell death in phenotypically distinct populations of myeloma cells in vitro and in vivo. The cytotoxic potential of TRAIL alone, and in combination with DOX, was assessed in vitro in purified CD138(+) and CD138(-) cells from the MM cell lines and samples from patients with MM. Mouse xenografts obtained by implanting CD138(-) MM cells were used to assess the efficacy of TRAIL, alone and in combination with DOX, in vivo. CD138(-) cells were shown to be more resistant to the cytotoxic activity of TRAIL than CD138(+) cells and have reduced expression of TRAIL death receptors. This resistance results in preferential killing of CD 138(+) cells during exposure of MM culture to TRAIL. Furthermore, prolonged exposure results in the appearance of TRAIL-resistant CD138(-) cells. However, when TRAIL is combined with doxorubicin, this results in complete eradication of MM cells in vivo. Most importantly, this treatment successfully eliminates CD138(-) cells implicated in tumour initiation and growth maintenance. These findings may explain the failure of current therapies and offer a promising new approach in the quest to cure MM and disseminated cancers.

Superior antitumoral activity of dimerized targeted single-chain TRAIL fusion proteins under retention of tumor selectivity

Although targeting of the death receptors (DRs) DR4 and DR5 still appears a suitable antitumoral strategy, the limited clinical responses to recombinant soluble TNF-related apoptosis inducing ligand (TRAIL) necessitate novel reagents with improved apoptotic activity/tumor selectivity. Apoptosis induction by a single-chain TRAIL (scTRAIL) molecule could be enhanced >10-fold by generation of epidermal growth factor receptor (EGFR)-specific scFv-scTRAIL fusion proteins. By forcing dimerization of scFv-scTRAIL based on scFv linker modification, we obtained a targeted scTRAIL composed predominantly of dimers (Db-scTRAIL), exceeding the activity of nontargeted scTRAIL ∼100-fold on Huh-7 hepatocellular and Colo205 colon carcinoma cells. Increased activity of Db-scTRAIL was also demonstrated on target-negative cells, suggesting that, in addition to targeting, oligomerization equivalent to an at least dimeric assembly of standard TRAIL per se enhances apoptosis signaling. In the presence of apoptosis sensitizers, such as the proteasomal inhibitor bortezomib, Db-scTRAIL was effective at picomolar concentrations in vitro (EC(50) ∼2 × 10(-12) M). Importantly, in vivo, Db-scTRAIL was well tolerated and displayed superior antitumoral activity in mouse xenograft (Colo205) tumor models. Our results show that both targeting and controlled dimerization of scTRAIL fusion proteins provides a strategy to enforce apoptosis induction, together with retained tumor selectivity and good in vivo tolerance.

An intermittent approach for cancer chemoprevention

Cancer chemoprevention approaches generally use long-term, continuous treatment, which can produce major preventive effects but which can also have unexpected serious adverse events. This raises the question of whether intermittent dosing schedules might reduce toxicity while retaining benefit, a concept that we call short-term intermittent therapy to eliminate premalignancy (SITEP). Recent preclinical studies support a novel SITEP approach whereby short-term, intermittent therapy eliminates premalignant cells via apoptosis that is induced by synthetic lethal interactions. Synthetic lethality allows personalized, selective elimination of premalignant clones without harming normal cells. This Opinion article provides a detailed discussion of the principle, method and future development of the SITEP approach.

Low-dose combinations of LBH589 and TRAIL can overcome TRAIL-resistance in colon cancer cell lines

BACKGROUND

Despite the considerable advances in the treatment of colorectal cancer, substantial changes in treatment strategies are required to overcome the problems of drug resistance and toxicity.

MATERIALS AND METHODS

Combinations of Pan-deacetylase inhibitor LBH589 and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) were studied in three colon cancer cell lines, HCT116, colo205, and HT29 (HCT116 and colo205 are TRAIL sensitive, whereas HT29 is TRAIL resistant).

RESULTS

It was found that TRAIL-induced cytotoxicity was enhanced by LBH589 cotreatment in the TRAIL-sensitive cell lines, and in the TRAIL-resistant HT29 cell line. The cytotoxicity of low-dose TRAIL plus LBH589 was found to be comparable to that of high-dose TRAIL plus LBH589. Additionally, TRAIL and LBH589 were significantly less toxic to normal UCB mononuclear cells than to the three colon cancer cell lines examined.

CONCLUSION

LBH589 enhances TRAIL-induced apoptosis in human colon cancer cell lines, especially those resistant to TRAIL-induced apoptosis.

Targeting the extrinsic apoptosis signaling pathway for cancer therapy

The extrinsic apoptosis pathway is triggered by the binding of death ligands of the tumor necrosis factor (TNF) family to their appropriate death receptors (DRs) on the cell surface. One TNF family member, TNF-related apoptosis-inducing ligand (TRAIL or Apo2L), seems to preferentially cause apoptosis of transformed cells and can be systemically administered in the absence of severe toxicity. Therefore, there has been enthusiasm for the use of TRAIL or agonist antibodies to the TRAIL DR4 and DR5 in cancer therapy. Nonetheless, many cancer cells are very resistant to TRAIL apoptosis in vitro. Therefore, there is much interest in identifying compounds that can be combined with TRAIL to amplify its apoptotic effects. In this review, I will provide a brief overview of apoptosis signaling by TRAIL and discuss apoptosis-sensitizing agents, focusing mainly on the proteasome inhibitor bortezomib (VELCADE) and some novel sensitizers that we have recently identified. Alternative ways to administer TRAIL or DR agonist antibodies as therapeutic agents will also be described. Finally, I will discuss some of the gaps in our understanding of TRAIL apoptosis signaling and suggest some research directions that may provide additional information for optimizing the targeting of the extrinsic apoptosis pathway for future cancer therapy.

A novel combination of TRAIL and doxorubicin enhances antitumor effect based on passive tumor-targeting of liposomes

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a novel anticancer agent for non-small cell lung cancer (NSCLC). However, approximately half of NSCLC cell lines are highly resistant to TRAIL. Doxorubicin (DOX) can sensitize NSCLC cells to TRAIL-induced apoptosis, indicating the possibility of combination therapy. Unfortunately, the therapeutic effect of a DOX and TRAIL combination is limited by multiple factors including the short serum half-life of TRAIL, poor compliance and application difficulty in the clinic, chronic DOX-induced cardiac toxicity, and the multidrug resistance (MDR) property of NSCLC cells. To solve such problems, we developed the combination of TRAIL liposomes (TRAIL-LP) and DOX liposomes (DOX-LP). An in vitro cytotoxicity study indicated that DOX-LP sensitized the NSCLC cell line A-549 to TRAIL-LP-induced apoptosis. Furthermore, this combination therapy of TRAIL-LP and DOX-LP displayed a stronger antitumor effect on NSCLC in xenografted mice when compared with free drugs or liposomal drugs alone. Therefore, the TRAIL-LP and DOX-LP combination therapy has excellent potential to become a new therapeutic approach for patients with advanced NSCLC.

Combined modality therapy with TRAIL or agonistic death receptor antibodies

Molecularly targeted therapies, such as antibodies and small molecule inhibitors have emerged as an important breakthrough in the treatment of many human cancers. One targeted therapy under development is tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) due to its ability to induce apoptosis in a variety of human cancer cell lines and xenografts, while lacking toxicity in most normal cells. TRAIL and apoptosis-inducing agonistic antibodies to the TRAIL death receptors have been the subject of many preclinical and clinical studies in the past decade. However, the sensitivity of individual cancer cell lines of a particular tumor type to these agents varies from highly sensitive to resistant. Various chemotherapy agents have been shown to enhance the apoptosis-inducing capacity of TRAIL receptor-targeted therapies and induce sensitization of TRAIL-resistant cells. This review provides an overview of the mechanisms associated with chemotherapy enhancement of TRAIL receptor-targeted therapies including modulation of the apoptotic (death receptor expression, FLIP, and Bcl-2 or inhibitors of apoptosis (IAP) families) as well as cell signaling (NFκB, Akt, p53) pathways. These mechanisms will be important in establishing effective combinations to pursue clinically and in determining relevant targets for future cancer therapies.

Efficacy of TRAIL treatment against HPV16 infected cervical cancer cells undergoing senescence following siRNA knockdown of E6/E7 genes

In this study we investigated E6 and E7 oncogenes from the Human Papilloma Virus as targets for siRNA knockdown in order to boost the efficacy of the anti-cancer drug 'tumor necrosis factor-related apoptosis inducing ligand' (TRAIL). SiHa cells were treated with TRAIL following transfection with E6/E7 siRNA and the expression of death receptors DR4 and DR5, cell viability, apoptosis, senescence and cell cycle analysis were undertaken using flow cytometry, MTT viability assay and cellular β-galactosidase activity assays. E6/E7 siRNA resulted in significant upregulation of death receptors DR4 and DR5 but did not result in an enhanced sensitivity to TRAIL. Our results indicate that E6/E7-siRNA induces senescence rather than apoptosis in SiHa cells. The occurrence of senescence in drug resistant cervical cancer cells such as the SiHa cell line by E6/E7 siRNA, among other factors, may prevent TRAIL induced activation of extrinsic and intrinsic pathways that lead to apoptotic cell death. Our findings are significant for combinatorial strategies for cancer therapy since the induction of senescence can preclude apoptosis rendering cells to be recalcitrant to TRAIL treatment.

Systemic delivery of TNF-related apoptosis-inducing ligand (TRAIL) elevates levels of tissue inhibitor of metalloproteinase-1 (TIMP-1) and prevents type 1 diabetes in nonobese diabetic mice

Recent studies have demonstrated that TNF-related apoptosis-inducing ligand (TRAIL) is a modulator of the immune response. The relation between TRAIL and type 1 diabetes (T1D) as an autoimmune inflammatory disease in vivo is relatively unknown. To explore the potential role of TRAIL in the development of T1D, we examined its in vivo effects in nonobese diabetic (NOD) mice. NOD mice at 7 wk of age were iv injected with an adenovirus carrying either human TRAIL (Ad.hTRAIL) or β-galactosidase genes. Blood glucose was monitored weekly, and the expression of hTRAIL was evaluated in plasma and liver of mice. To investigate whether hTRAIL elicits its effect through the induction of tissue inhibitor of metalloproteinase-1 (TIMP-1), we examined the concentration of plasma TIMP-1 by ELISA and the inhibition of matrix metalloproteinase (MMP) by gelatin zymography. Here, we show that Ad.hTRAIL-transduced mice had significantly reduced blood glucose levels and markedly increased production of TIMP-1 compared with control β-galactosidase animals. Pancreatic tissue isolated from Ad.hTRAIL-treated NOD mice showed reduced MMP activities associated with significantly improved insulitis. In addition, TIMP-1 in vitro suppressed cytokine-induced apoptosis in insulin-producing INS-1 cells. These results indicate that T1D can be prevented by TRAIL overexpression through enhancement of TIMP-1 function. Elevated TIMP-1 production inhibits the activity of MMPs, which may contribute to suppress the transmigration of diabetogenic T cells into the pancreatic islets and protects pancreatic β-cells from cytokine-induced apoptosis. Therefore, TRAIL and TIMP-1 induction may be potential targets to prevent development of T1D.

Combining naturally occurring polyphenols with TNF-related apoptosis-inducing ligand: a promising approach to kill resistant cancer cells?

TNF-related apoptosis-inducing ligand (TRAIL) and its receptors are attractive targets for anticancer therapy owing to their ability to trigger apoptosis selectively in cancer cells but not in normal cells. To date, many combinatorial strategies, such as chemotherapy or radiotherapy, have given encouraging results for overcoming TRAIL resistance in preclinical models. In this review, we provide an overview of the molecular mechanisms underlying sensitization to TRAIL-induced apoptosis by polyphenols. These naturally occurring compounds can restore tumor cell sensitivity to TRAIL-induced cell death with no apparent toxicity towards normal cells. Both extrinsic and intrinsic pathways can be modulated by polyphenols, the activation of which largely depends on the cell type, the particular polyphenolic compound, and the conditions of treatment. The large variety of polyphenol cellular targets could prove useful in circumventing TRAIL resistance. The relevance of these combined treatments for cancer therapy is discussed in the light of recent preclinical studies.

Treatment with recombinant tumor necrosis factor-related apoptosis-inducing ligand alleviates the severity of streptozotocin-induced diabetes

OBJECTIVE

To evaluate the potential therapeutic effect of recombinant human tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) treatment in a model of type 1 diabetes.

RESEARCH DESIGN AND METHODS

Recombinant TRAIL was added in vitro to primary human and mouse peripheral blood mononuclear cells (PBMCs) and isolated human islets to evaluate the expression of the immunoregulatory gene SOCS1. Diabetes was induced by five consecutive daily injections of low-concentration (50 mg/kg) streptozotocin (STZ) in C57 black mice (n = 24). A group of these mice (n = 12) was co-injected with recombinant TRAIL (20 microg/day) for 5 days, and the diabetic status (glycemia and body weight) was followed over time. After 6 weeks, circulating levels of insulin, TNF-alpha, and osteoprotegerin (OPG) were measured, and animals were killed to perform the histological analysis of the pancreas.

RESULTS

The in vitro exposure of both PBMCs and human islets to recombinant TRAIL significantly upregulated the expression of SOCS1. With respect to STZ-treated animals, mice co-injected with STZ+TRAIL were characterized by 1) lower levels of hyperglycemia, 2) higher levels of body weight and insulinemia, 3) a partial preservation of pancreatic islets with normal morphology, and 4) a lower expression of both systemic (TNF-alpha and OPG) and pancreatic (vascular cell adhesion molecule [VCAM]-1) inflammatory markers.

CONCLUSIONS

Overall, these data demonstrate that the administration of recombinant TRAIL ameliorates the severity of STZ-induced type 1 diabetes, and this effect was accompanied by the upregulation of SOCS1 expression.

Quercetin enhances TRAIL-induced apoptosis in prostate cancer cells via increased protein stability of death receptor 5

AIMS

Quercetin has been shown to enhance tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis of prostate cancer cells via mechanisms that include upregulation of death receptor (DR) 5, a protein reported to play an important role in sensitizing cancer cells to apoptosis. We aimed to determine the specific mechanisms underlying quercetin-induced DR5 expression.

MAIN METHODS

Human prostate cancer cells were exposed to quercetin and TRAIL. Trypan blue assays and terminal transferase dUTP nick-end labeling (TUNEL) assays evaluated changes in TRAIL resistance after quercetin treatment, and flow cytometry examined quercetin-induced death receptor expression in DU-145 cells. Western blotting, reverse transcription-polymerase chain reaction (RT-PCR) and transiently transfection were utilized to confirm apoptotic patterns of prostate cancer cells.

KEY FINDINGS

After stimulation with quercetin, DU-145 cells exhibited stronger sensitization to TRAIL. Quercetin treatment enhanced TRAIL-induced activation proteins in the caspase pathway, such as poly (ADP-ribose) polymerase (PARP), caspase-3, and caspase-9. Quercetin dose-dependently increased DR5 levels in prostate cancer cells, which was mediated by increased transcription and protein stability, but not mRNA stability. Ectopic expression of DR5 dose-dependently increased TRAIL-induced apoptosis.

SIGNIFICANCE

Our results showed that the role of quercetin and TRAIL combination therapy may provide a novel strategy for treating prostate cancer by overcoming critical mechanisms of apoptosis resistance.

Chalcones enhance TRAIL-induced apoptosis in prostate cancer cells

Chalcones exhibit chemopreventive and antitumor effects. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a naturally occurring anticancer agent that induces apoptosis in cancer cells and is not toxic to normal cells. We examined the cytotoxic and apoptotic effect of five chalcones in combination with TRAIL on prostate cancer cells. The cytotoxicity was evaluated by the MTT and LDH assays. The apoptosis was determined using flow cytometry with annexin V-FITC. Our study showed that all five tested chalcones: chalcone, licochalcone-A, isobavachalcone, xanthohumol, butein markedly augmented TRAIL-mediated apoptosis and cytotoxicity in prostate cancer cells and confirmed the significant role of chalcones in chemoprevention of prostate cancer.

[Treatment of osteosarcoma with TNF-related apoptosis-inducing ligand or in combination with doxorubicin in animal experiment]

OBJECTIVE

To examine the effect of TNF-related apoptosis-inducing ligand (TRAIL) and in combination with doxorubicin (ADM) to xenografted tumors in nude mice and to explore its potential mechanism.

METHODS

MG-63 cells (5 x 10(6)/ml) were suspended in 0.2 ml RPMI-1640 and inoculated subcutaneously into the lower limb of nude mice. Treatment groups were given TRAIL of different concentration or combination of TRAIL and ADM intraperitoneally. Normal saline was administrated in the control group. Anti-tumor effects were estimated by tumor volumes. Serum alkaline phosphatase (ALP) was detected by ALP kits. Induction of apoptosis in xenografted tumors was confirmed by TUNEL (TdT-mediated dUTP nick end labeling) assay. Expression of Bax was detected by immunohistochemical assay. Expression of TRAIL receptors was detected by RT-PCR assay.

RESULTS

Growth curve of tumors indicated that tumors carried by TRAIL-treated mice grew more slowly than that with normal saline and 2 microg TRAIL was more effective, Also tumors treated with combination of TRAIL and ADM grew more slowly than any other group. ALP activities of each group were moderately different but significance was not reached. TUNEL showed that there were more apoptotic cells in the combination group than any other group. Immunohistochemical assay showed that expression of Bax was up-regulated in the combination group. RT-PCR showed that expression of TRAIL-R2 mRNA was up-regulated in the combination group.

CONCLUSION

TRAIL can induce an effective apoptosis of osteosarcoma cells in vivo in a dose-dependent fashion. ADM can enhance the effect of TRAIL-mediated apoptosis. And up-regulations of Bax and TRAIL-R2 may be the involved mechanism.

KAAD-cyclopamine augmented TRAIL-mediated apoptosis in malignant glioma cells by modulating the intrinsic and extrinsic apoptotic pathway

Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising cancer therapeutic. The main obstacle in TRAIL-based therapy is that many glioma cells are resistant. In this study glioblastoma cell lines, human glioblastoma short-term cultures and human astrocytes were treated with 3-keto-N-aminoethylaminoethylcaproyldihydrocinnamoyl cyclopamine (KAAD-cyclopamine), tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) or the combination of both. Single treatment with KAAD-cyclopamine or TRAIL does not induce cytotoxicity in malignant glioma cells. However, treatment with KAAD-cyclopamine in combination with TRAIL induces rapid apoptosis in TRAIL-resistant glioma cells. Notably, normal human astrocytes were not affected by the combination treatment consisting of KAAD-cyclopamine and TRAIL. KAAD-cyclopamine led to an upregulation of death receptor 4 and 5 and down-regulation of bcl-2 and c-FLIP. Furthermore, overexpression of both bcl-2 and c-FLIP attenuated KAAD-cyclopamine facilitated TRAIL-mediated apoptosis. Taken together,we provided evidence that KAAD-cyclopamine facilitated TRAIL-mediated apoptosis at the level of the intrinsic and extrinsic apoptotic pathways in malignant glioma cells.

Ethyl alcohol extracts of Hizikia fusiforme sensitize AGS human gastric adenocarcinoma cells to tumor necrosis factor-related apoptosis-inducing ligand-mediated apoptosis

Resistance to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis has been reported in some cancer cells, including AGS human gastric adenocarcinoma cells. Hizikia fusiforme is a commonly used brown seaweed species in Korea that possesses potent antibacterial, antifungal, and anti-inflammatory activities. In this study, we demonstrated that treatment with TRAIL in combination with subtoxic concentrations of ethyl alcohol extract of H. fusiforme (EAHF) sensitized TRAIL-resistant AGS cells to TRAIL-mediated apoptosis. Combined treatment with EAHF and TRAIL increased chromatin condensation, DNA fragmentation, and sub-G1-phase DNA content. The restored sensitivity to TRAIL-induced apoptosis appeared to be correlated with the modulation of Bcl-2 family proteins and activation of caspases, which resulted in the cleavage of poly(ADP-ribose)polymerase. Taken together, the use of EAHF in combination with TRAIL may be an effective and selective anticancer strategy via suppressing the resistance to TRAIL-induced apoptosis in some tumor cell lines, including AGS cells.

Is TRAIL the holy grail of cancer therapy?

Inducing apoptosis has become an important approach in the development of new anti-cancer treatments. Tumour necrosis factor apoptosis inducing ligand (TRAIL) based therapies have emerged as one of the most promising examples of this as they selectively induce apoptosis in tumour cells. However, many primary tumours are inherently resistant to TRAIL-mediated apoptosis and require additional sensitisation. Here we review apoptotic and non-apoptotic TRAIL-signalling, and the therapeutic effects of TRAIL-based treatments both as monotherapy and in combination with sensitising agents.

Apo2L/TRAIL inhibits tumor growth and bone destruction in a murine model of multiple myeloma

PURPOSE

Multiple myeloma is an incurable disease, for which the development of new therapeutic approaches is required. Here, we report on the efficacy of recombinant soluble Apo2L/tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) to inhibit tumor progression and bone destruction in a xenogeneic model of human multiple myeloma.

EXPERIMENTAL DESIGN

We established a mouse model of myeloma, in which Apo2L/TRAIL-sensitive RPMI-8226 or KMS-11 cells, tagged with a triple reporter gene construct (NES-HSV-TK/GFP/Luc), were transplanted directly into the tibial marrow cavity of nude mice. Tumor burden was monitored progressively by bioluminescence imaging and the development of myeloma-induced osteolysis was measured using high resolution in vivo micro-computed tomography.

RESULTS

Tumor burden increased progressively in the tibial marrow cavity of mice transplanted with Apo2L/TRAIL-sensitive RPMI-8226 or KMS-11 cells associated with extensive osteolysis directly in the area of cancer cell transplantation. Treatment of mice with recombinant soluble Apo2L/TRAIL reduced myeloma burden in the bone marrow cavity and significantly protected against myeloma-induced osteolysis. The protective effects of Apo2L/TRAIL treatment on bone were mediated by the direct apoptotic actions of Apo2L/TRAIL on myeloma cells within the bone microenvironment.

CONCLUSIONS

This is the first in vivo study that investigates the efficacy of recombinant Apo2L/TRAIL on myeloma burden within the bone microenvironment and associated myeloma-induced bone destruction. Our findings that recombinant soluble Apo2L/TRAIL reduces myeloma burden within the bone microenvironment and protects the bone from myeloma-induced bone destruction argue against an inhibitory role of osteoprotegerin in Apo2L/TRAIL-induced apoptosis in vivo and highlight the need to clinically evaluate Apo2L/TRAIL in patients with multiple myeloma.

Response of bladder carcinoma cells to TRAIL and antisense oligonucleotide, Bcl-2 or clusterin treatments

PURPOSE

Bladder transitional cell carcinoma is the second most common urological malignancy, of which 80% are superficial disease limited to the bladder. Superficial bladder transitional cell carcinoma has a high propensity for recurrence and progression after initial resection, necessitating adjuvant intravesical therapy. TRAIL (tumor necrosis factor-related apoptosis inducing ligand) can selectively induce apoptosis in most tumor cells while sparing normal cells. TRAIL drives not only the death receptor pathway, but also the mitochondrial pathway through Bid. Due to the anti-apoptotic functions of Bcl-2 and clusterin on the mitochondrial apoptotic pathway the effects of down-regulating these proteins were examined in partially TRAIL resistant bladder transitional cell carcinoma cell lines.

MATERIALS AND METHODS

Antisense oligonucleotides targeting Bcl-2 and clusterin were used alone or combined with TRAIL and cytotoxicity was examined by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolim bromide) proliferation assay. Apoptotic pathway signals were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis/Western blotting after the various combination treatments. All statistical tests were 2 sided.

RESULTS

Although no direct correlation between TRAIL sensitivity and the relative expression levels of Bcl-2 and clusterin was found in the bladder transitional cell carcinoma cell lines examined, antisense oligonucleotide mediated the down-regulation of Bcl-2 and clusterin, increasing the sensitivity of the partially resistant cells to TRAIL. This was mediated through increased apoptotic signaling of the mitochondrial pathway, as evident by the increased activation of caspase-9 and 3, and cleaved DFF45. There was no benefit of combined antisense oligonucleotide therapy.

CONCLUSIONS

This study provides proof of principle that TRAIL combined with antisense oligonucleotide-Bcl-2 may have potential as a novel future treatment strategy for bladder transitional cell carcinoma.