Biomolecular Surfaces for the Capture and Reprogramming of Circulating Tumor Cells

Circulating Tumor Cells(CTC)have the potential to be used clinically as a diagnostic tool and a treatment tool in the fieldof oncology.As a diagnostic tool,CTC may be used to indicate the presence of a tumor before it is large enough to cause noticeablesymptoms.As a treatment tool,CTC isolated from patients may be used to test the efficacy of chemotherapy options topersonalize patient treatment.One way for tumors to spread is through metastasis via the circulatory system.CTC are able toexploit the natural leukocyte recruitment process that is initially mediated by rolling on transient selectin bonds.Our capturedevices take advantage of this naturally occurring recruitment step to isolate CTC from whole blood by flowing samples throughselectin and antibody-coated microtubes.Whole blood was spiked with a known concentration of labeled cancer cells and thenperfused through pre-coated microtubes.Microtubes were then rinsed to remove unbound cells and the number of labeled cellscaptured on the lumen was assessed.CTC were successfully captured from whole blood at a clinically relevant level on the orderof 10 cells per mL.Combination tubes with selectin and antibody coated surface exhibited higher capture rate than tubes coatedwith selectin alone or antibody alone.Additionally,CTC capture was demonstrated with the KG 1 a hematopoietic cell line andthe DU 145 epithelial cell line.Thus,the in vivo process of selectin-mediated CTC recruitment to distant vessel walls can be usedin vitro to target CTC to a tube lumen.The biomolecular coatings can also be used to capture CTC of hematopoietic andepithelial tumor origin and is demonstrated to sensitivities down to the order of 10 CTC per mL.In a related study aimed at reducing the blood borne metastatic cancer load,we have shown that cells captured to a surfacecan be neutralized by a receptor-mediated biochemical signal.In the proposed method we have shown that using a combinedselectin and TRAIL(TNF Related Apoptosis Inducing Ligand or Apo 2L)functionalized surface we are abl     

Selective TRAIL‐induced cytotoxicity to lung cancer cells mediated by miRNA response elements

Lung cancer is among the most common cancers, and the current therapeutic strategies are still inefficient in most cases. Tumour necrosis factor‐related apoptosis‐inducing ligand (TRAIL) is a promising biological agent for cancer treatment because of its potent pro‐apoptotic effect on cancer cells. However, TRAIL also induces apoptosis in normal cells and therefore may cause toxicity to normal tissues if clinically applied. To address this issue, we inserted microRNA response elements (MREs) of miR‐133a, miR‐137 and miR‐449a, which are all underexpressed in lung cancer cells, into an adenoviral vector to regulate TRAIL expression. This MRE‐regulated vector (Ad‐TRAIL‐MRE) was able to express TRAIL in a lung‐cancer‐specific fashion. No TRAIL expression was detected in normal cells. Consistently, Ad‐TRAIL‐MRE exerted cytotoxicity to lung cancer cells, rather than normal cells, perhaps via inducing selective apoptosis. The selective TRAIL‐mediated growth‐inhibiting effect was further confirmed in a tumour xenograft model. Also, Ad‐TRAIL‐MRE only resulted in very low hepatotoxicity when applied. Collectively, we generated a novel TRAIL‐expressing adenoviral vector that was regulated by MREs. This strategy permits TRAIL expression in a lung‐cancer‐specific manner and is worth further studying for clinical trials. Copyright © 2014 John Wiley & Sons, Ltd.     

ISG12a and its interaction partner NR4A1 are involved in TRAIL‐induced apoptosis in hepatoma cells

Tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL) can induce apoptosis in cancer cells while sparing normal cells, thereby leading to the development of TRAIL receptor agonists for cancer treatment. However, these agonist‐based therapeutics exhibit little clinical benefits due to the lack of biomarkers to predict whether patients are responsive to the treatment, as well as determine the resistance of cancer cells to TRAIL‐based agonists. Our previous study has demonstrated that ISG12a enhances TRAIL‐induced apoptosis and might serve as a biomarker to predict the TRAIL response. The downstream mechanism by which ISG12a augments TRAIL‐induced apoptosis remains to be elucidated. In this study, we found that ISG12a was localized in the mitochondria and nucleus and augmented TRAIL‐induced apoptosis through intrinsic apoptotic pathway. In addition, ISG12a interacted with NR4A1 and promoted its nuclear‐to‐cytoplasm translocation. Upon translocate to cytoplasm, NR4A1 targeted mitochondria and induced Bcl2 conformational change, thereby exposing its BH3 domain. Moreover, TRAIL treatment can induce NR4A1 expression through the activation of NF‐κB in TRAIL‐resistant Huh7 hepatoma cells. Knockdown of NR4A1 could overcome TRAIL resistance. However, in TRAIL‐sensitive LH86 liver cancer cells, TRAIL activated the Jun N‐terminal kinases signalling pathway. Overall, these results showed that both ISG12a and its interaction partner NR4A1 are involved in TRAIL‐mediated apoptosis in hepatoma cells.     

TRAIL‐induced apoptosis of FHIT‐negative lung cancer cells is inhibited by FHIT re‐expression

Fragile histidine triad (FHIT) is a tumor suppressor gene whose allelic loss is associated to a number of human cancers. FHIT protein acts as a diadenosine oligophosphate hydrolase, but its tumor suppressive activity appears as independent from its enzymatic activity. Tumor necrosis factor (TNF)‐related apoptosis inducing ligand (TRAIL) can induce apoptosis in the FHIT‐negative non‐small lung cancer cell line Calu‐1. We generated four FHIT‐inducible Calu‐1 cell clones and demonstrated that FHIT expression was able to protect cells from TRAIL‐induced apoptosis, without affecting TRAIL‐receptors surface expression. FHIT‐specific small interference RNA transfection of SV40‐immortalized normal bronchial BEAS cells that show levels of FHIT protein comparable to those of normal bronchial cells, resulted in a significant increase of TRAIL‐induced apoptosis. Of note, suramin‐mediated inhibition of FHIT enzymatic activity also enhanced TRAIL‐induced apoptosis. We conclude that FHIT expression in lung cancer cells is protective from TRAIL‐induced apoptosis. Our data suggest that FHIT exerts this protective effect downstream TRAIL‐receptors and likely requires its dinucleoside‐triphosphate hydrolase activity. As TRAIL represents in the near future a good candidate for death ligands‐based anticancer therapy, its potential therapeutic use should be envisaged as preliminary to molecular genetics interventions or drug‐induced epigenetic modulations aimed to restoring FHIT gene expression levels in non‐small cells lung tumors. J. Cell. Physiol. 220: 492–498, 2009. © 2009 Wiley‐Liss, Inc.     

TAK1 activates AMPK‐dependent cytoprotective autophagy in TRAIL‐treated epithelial cells

The capacity of tumour necrosis factor‐related apoptosis‐inducing ligand (TRAIL) to trigger apoptosis preferentially in cancer cells, although sparing normal cells, has motivated clinical development of TRAIL receptor agonists as anti‐cancer therapeutics. The molecular mechanisms responsible for the differential TRAIL sensitivity of normal and cancer cells are, however, poorly understood. Here, we show a novel signalling pathway that activates cytoprotective autophagy in untransformed human epithelial cells treated with TRAIL. TRAIL‐induced autophagy is mediated by the AMP‐activated protein kinase (AMPK) that inhibits mammalian target of rapamycin complex 1, a potent inhibitor of autophagy. Interestingly, the TRAIL‐induced AMPK activation is refractory to the depletion of the two known AMPK‐activating kinases, LKB1 and Ca(2+)/calmodulin‐dependent kinase kinase‐β, but depends on transforming growth factor‐β‐activating kinase 1 (TAK1) and TAK1‐binding subunit 2. As TAK1 and AMPK are ubiquitously expressed kinases activated by numerous cytokines and developmental cues, these data are most likely to have broad implications for our understanding of cellular control of energy homoeostasis as well as the resistance of untransformed cells against TRAIL‐induced apoptosis.     

Overexpression of Par‐4 sensitizes TRAIL‐induced apoptosis via inactivation of NF‐κB and Akt signaling pathways in renal cancer cells

The prostate‐apoptosis‐response‐gene‐4 (Par‐4) is up‐regulated in prostate cells undergoing programmed cell death. Furthermore, Par‐4 protein has been shown to function as an effector of cell death in response to various apoptotic stimuli that trigger mitochondria and membrane receptor‐mediated cell death pathways. In this study, we investigated how Par‐4 modulates TRAIL‐mediated apoptosis in TRAIL‐resistant Caki cells. Par‐4 overexpressing cells were strikingly sensitive to apoptosis induced by TRAIL compared with control cells. Par‐4 overexpressing Caki cells treated with TRAIL showed an increased activation of the initiator caspase‐8 and the effector caspase‐3, together with an enforced cleavage of XIAP and c‐FLIP. TRAIL‐induced reduction of XIAP and c‐FLIP protein levels in Par‐4 overexpressing cells was prevented by z‐VAD pretreatment. In addition, the surface DR5 protein level was increased in TRAIL‐treated Par‐4 overexpressing cells. Interestingly, even though a deletion of leucine zipper domain in Par‐4 recovered Bcl‐2 level to basal level induced by wild type Par‐4, it partly decreased sensitivity to TRAIL in Caki cells. In addition, exposure of Caki/Par‐4 cells to TRAIL led to reduction of phosphorylated Akt levels, but deletion of leucine zipper domain of Par‐4 did not affect these phosphorylated Akt levels. In conclusion, we here provide evidence that ectopic expression of Par‐4 sensitizes Caki cells to TRAIL via modulation of multiple targets, including DR5, Bcl‐2, Akt, and NF‐κB. J. Cell. Biochem. 109: 885–895, 2010. © 2010 Wiley‐Liss, Inc.     

Laminar shear stress elicit distinct endothelial cell e‐selectin expression pattern via TNFα and IL‐1β activation

The ability to discriminate cell adhesion molecule expression between healthy and inflamed endothelium is critical for therapeutic intervention in many diseases. This study explores the effect of laminar flow on TNFα‐induced E‐selectin surface expression levels in human umbilical vein endothelial cells (HUVECs) relative to IL‐1β‐induced expression via flow chamber assays. HUVECs grown in static culture were either directly (naïve) activated with cytokine in the presence of laminar shear or pre‐exposed to 12 h of laminar shear (shear‐conditioned) prior to simultaneous shear and cytokine activation. Naïve cells activated with cytokine in static served as control. Depending on the cell shear history, fluid shear is found to differently affect TNFα‐induced relative to IL‐1β‐induced HUVEC expression of E‐selectin. Specifically, E‐selectin surface expression by naïve HUVECs is enhanced in the 8–12 h activation time range with simultaneous exposure to shear and TNFα (shear‐TNFα) relative to TNFα static control whereas enhanced E‐selectin expression is observed in the 4–24 h range for shear‐IL‐1β treatment relative to IL‐1β static control. While exposure of HUVECs to shear preconditioning mutes shear‐TNFα‐induced E‐selectin expression, it enhances or down‐regulates shear‐IL‐1β‐induced expression dependent on the activation period. Under dual‐cytokine‐shear conditions, IL‐1β signaling dominates. Overall, a better understanding of E‐selectin expression pattern by human ECs relative to the combined interaction of cytokines, shear profile and history can help elucidate many disease pathologies. Biotechnol. Bioeng. 2013; 110: 999–1003. © 2012 Wiley Periodicals, Inc.     

NDV‐D90 inhibits 17β‐estradiol‐mediated resistance to apoptosis by differentially modulating classic and nonclassic estrogen receptors in breast cancer cells

Newcastle disease virus (NDV) is endowed with the oncolytic ability to kill tumor cells, while rarely causing side effects in normal cells. Both estrogen receptor α (ERα) and the G protein estrogen receptor (GPER) modulate multiple biological activities in response to estrogen, including apoptosis in breast cancer (BC) cells. Here, we investigated whether NDV‐D90, a novel strain isolated from natural sources in China, promoted apoptosis by modulating the expression of ERα or the GPER in BC cells exposed to 17β‐estradiol (E2). We found that NDV‐D90 significantly killed the tumor cell lines MCF‐7 and BT549 in a time‐ and dose‐dependent manner. We also found that NDV‐D90 exerted its effects on the two cell lines mainly by inducing apoptosis but not necrosis. NDV‐D90 induced apoptosis via the intrinsic and extrinsic signaling pathways in MCF‐7 cells (ER‐positive cells) during E2 exposure not only by disrupting the E2/ERα axis and enhancing GPER expression but also by modulating the expression of several apoptosis‐related proteins through ERα‐and GPER‐independent processes. NDV‐D90 promoted apoptosis via the intrinsic signaling pathway in BT549 cells (ER‐negative cells), possibly by impairing E2‐mediated GPER expression. Furthermore, NDV‐D90 exerted its antitumor effects in vivo by inducing apoptosis. Overall, these results demonstrated that NDV‐D90 promotes apoptosis by differentially modulating the expression of ERα and the GPER in ER‐positive and negative BC cells exposed to estrogen, respectively, and can be utilized as an effective approach to treating BC.     

Osteoprotegerin production by breast cancer cells is suppressed by dexamethasone and confers resistance against TRAIL‐induced apoptosis

Osteoprotegerin (OPG) is a decoy receptor for receptor activator of NF‐κB ligand (RANKL) and TNF‐related apoptosis‐inducing ligand (TRAIL). While RANKL is essential for osteoclastogenesis and facilitates breast cancer migration into bone, TRAIL promotes breast cancer apoptosis. We analyzed the expression of OPG and TRAIL and its modulation in estrogen receptor‐positive MCF‐7 cells and receptor‐negative MDA‐MB‐231 cells. In both cells, OPG mRNA levels and protein secretion were dose‐ and time‐dependently enhanced by interleukin (IL)‐1β and suppressed by dexamethasone. In contrast to MCF‐7 cells, MDA‐MB‐231 abundantly expressed TRAIL mRNA, which was enhanced by IL‐1β and inhibited by dexamethasone. TRAIL activated pro‐apoptotic caspase‐3, ‐7, and poly‐ADP‐ribose polymerase and decreased cell numbers of MDA‐MB‐231, but had no effect on MCF‐7 cells. Gene silencing siRNA directed against OPG resulted in a 31% higher apoptotic rate compared to non‐target siRNA‐treated MDA‐MB‐231 cells. Furthermore, TRAIL induced significantly less apoptosis in cells cultured in conditioned media (containing OPG) compared to cells exposed to TRAIL in fresh medium lacking OPG (P < 0.01) and these protective effects were reversed by blocking OPG with its specific ligand RANKL (P < 0.05). The association between cancer cell survival and OPG production by MDA‐MB‐231 cells was further supported by the finding, that modulation of OPG secretion using IL‐1β or dexamethasone prior to TRAIL exposure resulted in decreased and increased rate of apoptosis, respectively (P < 0.05). Thus, OPG secretion by breast cancer cells is modulated by cytokines and dexamethasone, and may represent a critical resistance mechanism that protects against TRAIL‐induced apoptosis. J. Cell. Biochem. 108: 106–116, 2009. © 2009 Wiley‐Liss, Inc.     

Mechanisms of resistance of normal cells to TRAIL induced apoptosis vary between different cell types

Resistance of normal cells to tumour necrosis factor related apoptosis inducing ligand (TRAIL) induced apoptosis is believed to be mediated by expression of two decoy receptors. Here we show that the expression and localisation of TRAIL receptors (TRAIL-Rs) vary between different cells and that resistance to TRAIL is mediated by different mechanisms. The decoy receptor, TRAIL-R3, appeared important in protection of endothelial cells, whereas lack of surface death receptor expression and as yet unknown intracellular inhibitor(s) of apoptosis downstream of caspase-3 may play a major role in protection of melanocytes and fibroblasts from TRAIL induced apoptosis, respectively. Differential subcellular location of decoy receptors may be an important determinant of their effectiveness in different types of normal cells.     

Quercetin sensitizes pancreatic cancer cells to TRAIL-induced apoptosis through JNK-mediated cFLIP turnover

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent that can selectively kill cancer cells. Nonetheless, many cancers are resistant to TRAIL, and the molecular mechanisms of TRAIL resistance in cancer, particularly pancreatic cancer, are still unclear. In this study, we tested the hypothesis that quercetin, a flavonoid, induces apoptosis in TRAIL-resistant pancreatic cancer cells. Although quercetin alone had no significant cytotoxic effect, when combined with TRAIL, it promoted TRAIL-induced apoptosis that required mitochondrial outer membrane permeabilization. A BH3-only protein BID knockdown dramatically attenuated TRAIL/quercetin-induced apoptosis. The expression levels of cellular FLICE-like inhibitory protein (cFLIP) decreased in a dose-dependent manner in the presence of quercetin, and overexpression of cFLIP was able to robustly rescue pancreatic cancer cells from TRAIL/quercetin-induced apoptosis. Additionally, quercetin activated c-Jun N-terminal kinase (JNK) in a dose-dependent manner, which in turn induced the proteasomal degradation of cFLIP, and JNK activation also sensitized pancreatic cancer cells to TRAIL-induced apoptosis. Thus, our results suggest that quercetin induces TRAIL-induced apoptosis via JNK activation-mediated cFLIP turnover.     

Enhanced proliferation and increased IFN-gamma production in T cells by signal transduced through TNF-related apoptosis-inducing ligand

TNF-related apoptosis-inducing ligand (TRAIL, also called Apo2L), a novel member of TNF superfamily, induces apoptosis in transformed cell lines of diverse origin. TRAIL is expressed in most of the cells, and the expression is up-regulated in activated T cells. Four receptors for TRAIL have been identified, and there is complex interplay between TRAIL and TRAIL receptors in vivo. The actual biological function of TRAIL/TRAIL receptor is still not clear. Growing evidence has demonstrated that members of TNF superfamily transduce signals after engagement with their receptors. Cross-linking of TRAIL by plate-bound rTRAIL receptor, death receptor 4-Fc fusion protein enhanced T cell proliferation and increased IFN-gamma production in conjunction with immobilized suboptimal anti-CD3 stimulation in mouse splenocytes. The increase of T cell proliferation by death receptor 4-Fc was dose dependent, and this effect could be blocked by soluble rTRAIL proteins, indicating the occurrence of reverse signaling through TRAIL on T cell. The enhanced secretion of IFN-gamma mediated via TRAIL could be blocked by SB203580, a p38 mitogen-activated protein kinase-specific inhibitor. Thus, in addition to its role in inducing apoptosis by binding to the death receptors, TRAIL itself can enhance T cell proliferation after TCR engagement and signal the augmentation of IFN-gamma secretion via a p38-dependent pathway. This provides another example of reverse signaling by a member of TNF superfamily. In conclusion, our data suggest that TRAIL can itself transduce a reverse signal, and this may shed light on the biological function of TRAIL.     

Trametinib potentiates TRAIL‐induced apoptosis via FBW7‐dependent Mcl‐1 degradation in colorectal cancer cells

Trametinib is a MEK1/2 inhibitor and exerts anticancer activity against a variety of cancers. However, the effect of Trametinib on colorectal cancer (CRC) is not well understood. In the current study, our results demonstrate the ability of sub‐toxic doses of Trametinib to enhance TRAIL‐mediated apoptosis in CRC cells. Our findings also indicate that Trametinib and TRAIL activate caspase‐dependent apoptosis in CRC cells. Moreover, Mcl‐1 overexpression can reduce apoptosis in CRC cells treated with Trametinib with or without TRAIL. We further demonstrate that Trametinib degrades Mcl‐1 through the proteasome pathway. In addition, GSK‐3β phosphorylates Mcl‐1 at S159 and promotes Mcl‐1 degradation. The E3 ligase FBW7, known to polyubiquitinate Mcl‐1, is involved in Trametinib‐induced Mcl‐1 degradation. Taken together, these results provide the first evidence that Trametinib enhances TRAIL‐mediated apoptosis through FBW7‐dependent Mcl‐1 ubiquitination and degradation.     

Phenotypic variations of TRAIL sensitivity in cloned populations of prostate cancer cells

Factors that regulate the induction of apoptosis of tumour cells are potential candidates for therapeutic intervention for the majority of cancers. Studying modifiers of apoptotic responses, such as members of the tumour necrosis factor receptor superfamily, may give clues as to how induction of apoptosis in tumours could be maximized to enhance the benefit of treatment regimes. Tumour necrosis factor‐related apoptosis‐inducing ligand (TRAIL) is a promising anti‐tumour molecule since its activity is specific for tumour cell populations. TRAIL binds to death receptors, inducing apoptosis in susceptible cells. The mechanisms which determine whether tumour cells are susceptible to TRAIL are unclear, and several mechanisms have been proposed, including expression of osteoprotegerin (OPG), decoy receptors, and factors that affect intracellular signalling of pro‐apoptotic molecules, such as c‐FLIP. Here we show that experiments to modulate the activity of one of these factors, OPG, by over‐expression and also by stable knockdown of OPG expression, alters the TRAIL sensitivity of PC3 prostate cancer cells. However we show that some observed effects, which appear to support the hypothesis that OPG prevents TRAIL‐induced apoptosis of tumour cells, may be due to variation of the TRAIL response of sub‐clones of tumour cells, even within a cloned population. These results highlight potential limitations of experiments designed to test contribution of factors affecting intrinsic apoptosis susceptibility using cloned tumour cell populations. J. Cell. Biochem. 104: 1452–1464, 2008. © 2008 Wiley‐Liss, Inc.     

TRAIL/TRAIL‐R in hematologic malignancies

Defects in apoptosis are observed in many cancer cell types and contribute in a relevant way to tumorigenesis. Apoptosis is a complex and well‐regulated cell death program that plays a key role in the control of cell homeostasis, particularly at the level of the hematopoietic system. Apoptosis can be initiated through two different mechanisms involving either activation of the death receptors (extrinsic pathway) or activation of a mitochondrial apoptotic process (intrinsic pathway). Among the various death receptors a peculiar role is played by TNF‐related apoptosis‐inducing ligand (TRAIL)‐receptors (TRAIL‐Rs) and their ligand TRAIL. TRAIL recently received considerable interest for its potent anti‐tumor killing activity, sparing normal cells. Here, we will review the expression and the abnormalities of TRAIL/TRAIL‐R system in hematologic malignancies. The large majority of primary hematologic tumors are resistant to TRAIL‐mediated apoptosis, basically due to the activation of anti‐apoptotic signaling pathway (such as NF‐κB), overexpression of anti‐apoptotic proteins (such as FLIP, Bcl‐2, XIAP) or expression of TRAIL decoy receptors or reduced TRAIL‐R1/‐R2 expression. Strategies have been developed to bypass this TRAIL resistance and are based on the combination of TRAIL with chemotherapy or radiotherapy, or with proteasome or histone deacetylase or NF‐κB inhibitors. The agents used in combination with TRAIL either enhance TRAIL‐R1/‐R2 expression or decrease expression of anti‐apoptotic proteins (c‐FLIP, XIAP, Bcl‐2). Many of these combinatorial therapies hold promise for future developments in treatment of hematologic malignancies. J. Cell. Biochem. 110: 21–34, 2010. © 2010 Wiley‐Liss, Inc.     

TRADD is critical for resistance to TRAIL-induced cell death through NF-κB activation

One major obstacle in the clinical application of TRAIL as a cancer therapeutic agent is the acquisition of TRAIL resistance. We found that deficiency of TRADD sensitizes cells to TRAIL-induced apoptosis. Enhanced cell death in TRADD(-/-) MEFs is associated with defective NF-κB activation, indicating that the pro-survival function of TRADD in TRAIL signaling is mediated at least in part via NF-κB activation. Moreover, siRNA knock-down of TRADD in cancer cells sensitizes them to TRAIL-induced apoptosis. Thus, TRADD has a survival role in TRAIL signaling and may be one potential target for overcoming TRAIL resistance in cancer therapy.     

Down-regulation of DcR2 sensitizes androgen-dependent prostate cancer LNCaP cells to TRAIL-induced apoptosis

Background

Dysregulation of many apoptotic related genes and androgens are critical in the development, progression, and treatment of prostate cancer. The differential sensitivity of tumour cells to TRAIL-induced apoptosis can be mediated by the modulation of surface TRAIL receptor expression related to androgen concentration. Our previous results led to the hypothesis that downregulation of TRAIL-decoy receptor DcR2 expression following androgen deprivation would leave hormone sensitive normal prostate cells vulnerable to the cell death signal generated by TRAIL via its pro-apoptotic receptors. We tested this hypothesis under pathological conditions by exploring the regulation of TRAIL-induced apoptosis related to their death and decoy receptor expression, as also to hormonal concentrations in androgen-sensitive human prostate cancer, LNCaP, cells.

Results

In contrast to androgen-insensitive PC3 cells, decoy (DcR2) and death (DR5) receptor protein expression was correlated with hormone concentrations and TRAIL-induced apoptosis in LNCaP cells. Silencing of androgen-sensitive DcR2 protein expression by siRNA led to a significant increase in TRAIL-mediated apoptosis related to androgen concentration in LNCaP cells.

Conclusions

The data support the hypothesis that hormone modulation of DcR2 expression regulates TRAIL-induced apoptosis in LNCaP cells, giving insight into cell death induction in apoptosis-resistant hormone-sensitive tumour cells from prostate cancer. TRAIL action and DcR2 expression modulation are potentially of clinical value in advanced tumour treatment.     

TRAIL mediates apoptosis in cancerous but not normal primary cultured cells of the human reproductive tract

Cancer of the reproductive tract encompasses malignancies of the uterine corpus, cervix, ovary, Fallopian tube, among others and accounts for 15% of female cancer mortalities. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) mediates apoptosis by binding to death receptors and offers a promising cancer treatment. The goal of this study was to investigate and characterize the effect of TRAIL in endometrial cancer cell lines and normal (non-cancerous) epithelial cells of endometrial origin. We also examined the effect of TRAIL in other primary cultured cancers and normal cells of the human female reproductive tract and evaluated if TRAIL mediated apoptosis correlated with death receptors and decoy receptors 1 and 2. Herein, we demonstrate that TRAIL at concentrations which kill cancerous cells, does not mediate apoptosis or alter cell viability in normal human endometrium, ovary, cervix or Fallopian tube. The partial inhibition by a caspase 9 inhibitor and the total inhibition by a caspase 8 inhibitor demonstrates the dependency on the extrinsic apoptotic pathway. The selective mortality does not correlate with the presence of death or decoy receptors. These results suggest that TRAIL may be an effective treatment for endometrial cancer and other female reproductive cancers, with minimal secondary effects on healthy tissue. This work was supported by a grant from the Wellcome Trust GR071469 (GIO) and the Chilean national science grants FONDECYT 1060495 (GIO) and 1020675 (MC). An erratum to this article is available at .     

ZD1839 (Gefitinib, 'Iressa'), an epidermal growth factor receptor-tyrosine kinase inhibitor, enhances the anti-cancer effects of TRAIL in human esophageal squamous cell carcinoma

The EGF (epidermal growth factor) receptor-tyrosine kinase inhibitor ZD1839 (Gefitinib, 'Iressa') blocks the cell signaling pathways involved in cell proliferation, survival, and angiogenesis in various cancer cells. TNF-related death apoptosis inducing ligand (TRAIL) acts as an anticancer agent. We investigated the antitumor effects of ZD1839 alone or in combination with TRAIL against human esophageal squamous cell cancer (ESCC) lines. Although all ESCC cells expressed EGF receptor at a protein level, the effect of ZD1839 on cell growth did not correlate with the level of EGFR expression and phosphorylation of EGF receptor protein in ESCC lines. ZD1839 caused a dose-dependent growth arrest at G0-G1 phase associated with increased p27 expression. As TE8 cells are resistant to TRAIL, we tested whether ZD1839 combined with TRAIL induced apoptosis of TE8 cells via the inhibition of EGF receptor signaling by ZD1839. ZD1839 inhibited the phosphorylation of Akt, and enhanced TRAIL-induced apoptosis via activation of caspase-3 and caspase-9, and inactivation of Bcl-xL. Our results indicated that ZD1839 has anti-cancer properties against human esophageal cancer cells. ZD1839 also augmented the anti-cancer activity of TRAIL, even in TRAIL-resistant tumors. These results suggest that treatment with ZD1839 and TRAIL may have potential in the treatment of ESCC patients.     

Hepatocellular carcinoma: targeting of oncogenic signaling networks in TRAIL resistant cancer cells

Apoptotic response in hepatocellular carcinoma (HCC) cells is impaired because of interconnectivity of proteins into complexes and signaling networks that are highly divergent in time and space. TNF-related apoptosis-inducing ligand (TRAIL) has emerged as an attractive anticancer agent reported to selectively induce apoptosis in cancer cells. Although diametrically opposed roles of TRAIL are reported both as an inducer of apoptosis and regulator of metastasis, overwhelmingly accumulating experimental evidence highlighting apoptosis inducing activity of TRAIL is directing TRAIL into clinical trials. Insights from TRAIL mediated signaling in HCC research are catalyzing new lines of study that should not only explain molecular mechanisms of disease but also highlight emerging paradigms in restoration of TRAIL mediated apoptosis in resistant cancer cells. It is becoming progressively more understandable that phytochemicals derived from edible plants have shown potential in modelling their interactions with their target proteins. Rapidly accumulating in vitro and in-vivo evidence indicates that phytonutrients have anticancer activity in rodent models of hepatocellular carcinoma. In this review we bring to limelight how phytonutrients restore apoptosis in hepatocellular carcinoma cells by rebalancing pro-apoptotic and anti-apoptotic proteins. Evidence has started to emerge, that reveals how phytonutrients target pharmacologically intractable proteins to suppress cancer. Target-based small-molecule discovery has entered into the mainstream research in the pharmaceutical industry and a better comprehension of the genetics of patients will be essential for identification of responders and non-responders.