Cell cycle-arrested tumor cells exhibit increased sensitivity towards TRAIL-induced apoptosis

DMC-siERCC2 hybrid nanoparticle enhances TRAIL sensitivity by inducing cell cycle arrest for glioblastoma treatment

ERCC2 plays a pivotal role in DNA damage repair, however, its specific function in cancer remains elusive. In this study, we made a significant breakthrough by discovering a substantial upregulation of ERCC2 expression in glioblastoma (GBM) tumor tissue. Moreover, elevated levels of ERCC2 expression were closely associated with poor prognosis. Further investigation into the effects of ERCC2 on GBM revealed that suppressing its expression significantly inhibited malignant growth and migration of GBM cells, while overexpression of ERCC2 promoted tumor cell growth. Through mechanistic studies, we elucidated that inhibiting ERCC2 led to cell cycle arrest in the G0/G1 phase by blocking the CDK2/CDK4/CDK6/Cyclin D1/Cyclin D3 pathway. Notably, we also discovered a direct link between ERCC2 and CDK4, a critical protein in cell cycle regulation. Additionally, we explored the potential of TRAIL, a low-toxicity death ligand cytokine with anticancer properties. Despite the typical resistance of GBM cells to TRAIL, tumor cells undergoing cell cycle arrest exhibited significantly enhanced sensitivity to TRAIL. Therefore, we devised a combination strategy, employing TRAIL with the nanoparticle DMC-siERCC2, which effectively suppressed the GBM cell proliferation and induced apoptosis. In summary, our study suggests that targeting ERCC2 holds promise as a therapeutic approach to GBM treatment.

Cell cycle progression and transmitotic apoptosis resistance promote escape from extrinsic apoptosis

Extrinsic apoptosis relies on TNF-family receptor activation by immune cells or receptor-activating drugs. Here, we monitored cell cycle progression at a resolution of minutes to relate apoptosis kinetics and cell-to-cell heterogeneities in death decisions to cell cycle phases. Interestingly, we found that cells in S phase delay TRAIL receptor-induced death in favour of mitosis, thereby passing on an apoptosis-primed state to their offspring. This translates into two distinct fates, apoptosis execution post mitosis or cell survival from inefficient apoptosis. Transmitotic resistance is linked to Mcl-1 upregulation and its increased accumulation at mitochondria from mid-S phase onwards, which allows cells to pass through mitosis with activated caspase-8, and with cells escaping apoptosis after mitosis sustaining sublethal DNA damage. Antagonizing Mcl-1 suppresses cell cycle-dependent delays in apoptosis, prevents apoptosis-resistant progression through mitosis and averts unwanted survival after apoptosis induction. Cell cycle progression therefore modulates signal transduction during extrinsic apoptosis, with Mcl-1 governing decision making between death, proliferation and survival. Cell cycle progression thus is a crucial process from which cell-to-cell heterogeneities in fates and treatment outcomes emerge in isogenic cell populations during extrinsic apoptosis. This article has an associated First Person interview with the first author of the paper.

Retinoblastoma protein promotes uterine epithelial cell cycle arrest and necroptosis for embryo invasion

Retinoblastoma protein (RB) encoded by Rb1 is a prominent inducer of cell cycle arrest (CCA). The hormone progesterone (P₄ ) promotes CCA in the uterine epithelium and previous studies indicated that P₄ activates RB by reducing the phosphorylated, inactive form of RB. Here, we show that embryo implantation is impaired in uterine-specific Rb1 knockout mice. We observe persistent cell proliferation of the Rb1-deficient uterine epithelium until embryo attachment, loss of epithelial necroptosis, and trophoblast phagocytosis, which correlates with subsequent embryo invasion failure, indicating that Rb1-induced CCA and necroptosis of uterine epithelium are involved in embryo invasion. Pre-implantation P₄ supplementation is sufficient to restore these defects and embryo invasion. In Rb1-deficient uterine epithelial cells, TNFα-primed necroptosis is impaired, which is rescued by the treatment with a CCA inducer thymidine or P₄ through the upregulation of TNF receptor type 2. TNFα is expressed in the luminal epithelium and the embryo at the embryo attachment site. These results provide evidence that uterine Rb1-induced CCA is involved in TNFα-primed epithelial necroptosis at the implantation site for successful embryo invasion.

Sample-based modeling reveals bidirectional interplay between cell cycle progression and extrinsic apoptosis

Apoptotic cell death can be initiated through the extrinsic and intrinsic signaling pathways. While cell cycle progression promotes the responsiveness to intrinsic apoptosis induced by genotoxic stress or spindle poisons, this has not yet been studied conclusively for extrinsic apoptosis. Here, we combined fluorescence-based time-lapse monitoring of cell cycle progression and cell death execution by long-term time-lapse microscopy with sampling-based mathematical modeling to study cell cycle dependency of TRAIL-induced extrinsic apoptosis in NCI-H460/geminin cells. In particular, we investigated the interaction of cell death timing and progression of cell cycle states. We not only found that TRAIL prolongs cycle progression, but in reverse also that cell cycle progression affects the kinetics of TRAIL-induced apoptosis: Cells exposed to TRAIL in G1 died significantly faster than cells stimulated in S/G2/M. The connection between cell cycle state and apoptosis progression was captured by developing a mathematical model, for which parameter estimation revealed that apoptosis progression decelerates in the second half of the cell cycle. Similar results were also obtained when studying HCT-116 cells. Our results therefore reject the null hypothesis of independence between cell cycle progression and extrinsic apoptosis and, supported by simulations and experiments of synchronized cell populations, suggest that unwanted escape from TRAIL-induced apoptosis can be reduced by enriching the fraction of cells in G1 phase. Besides novel insight into the interrelation of cell cycle progression and extrinsic apoptosis signaling kinetics, our findings are therefore also relevant for optimizing future TRAIL-based treatment strategies.

Inhibition of cyclinB1 Suppressed the Proliferation, Invasion, and Epithelial Mesenchymal Transition of Hepatocellular Carcinoma Cells and Enhanced the Sensitivity to TRAIL-Induced Apoptosis

Background

CyclinB1 is highly expressed in various tumor tissues and plays an important role in tumor progression. However, its role in hepatocellular carcinoma (HCC) remains unclear. Therefore, the aim of this study was to explore the role of cyclinB1 in the development and progression of HCC.

Methods

The expression of cyclinB1 was analyzed using the Gene Expression Profiling Interactive Analysis (GEPIA) database, and detected in HCC tissues and HCC cell lines through quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting. CyclinB1-short hairpin RNA (Sh-cyclinB1) was transfected into HCC cells to knockdown cyclinB1, and the effect of cyclinB1 knockdown on HCC was examined via the MTT assay, colony formation assay, wound healing assay, scratch assay, cell cycle analysis in vitro, and xenograft model in nude mice. In addition, the role of cyclinB1 on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis was measured using flow cytometry and Western blotting.

Results

The GEPIA database analysis showed that cyclinB1 was highly expressed in HCC tissues. The results of qRT-PCR and Western blotting proved that the expression of cyclinB1 was significantly increased in HCC tissues and cell lines. The data of the MTT assay, colony formation assay, and cell cycle analysis indicated that cyclinB1 knockdown inhibited the proliferation of HCC cells. In addition, cell migration, invasion, and epithelial mesenchymal transition were also impaired by cyclinB1 knockdown. Furthermore, the xenograft model in nude mice demonstrated that inhibition of cyclinB1 suppressed tumor growth and metastasis in vivo. Finally, the results of flow cytometry and Western blotting indicated that inhibition of cyclinB1 enhanced the sensitivity of HCC cells to TRAIL-induced apoptosis.

Conclusion

Overall, these data provide reasonable evidence that cyclinB1 may serve as a proto-oncogene during the progression of HCC.

Geranium thunbergii extract-induced G1 phase cell cycle arrest and apoptosis in gastric cancer cells

Geranium thunbergii is a traditional East Asian medicine for stomach diseases including dysentery and stomach ulcers in East Asia and has been reported to possess biological activity. The benefits of G. thunbergii in gastric cancer are unknown. In this study, we demonstrate that G. thunbergii extract suppresses proliferation and induces death and G1/S cell cycle arrest of gastric cancer cells. Proliferation was significantly inhibited in a time- and dose-dependent manner. Cell cycle arrest was associated with significant decreases in CDK4/cyclinD1 complex and CDK2/cyclinE complex genes expression. In addition, the protein expression of caspase-3 was decreased and that of activated poly (ADP-ribose) polymerase (PARP) was increased, which indicated apoptosis. The expressions of the Bax and Bcl-2, which are apoptosis related proteins, were upregulated and down-regulated, respectively. The results indicate that G. thunbergii extract can inhibit proliferation and induce both G/S cell cycle arrest and apoptosis of gastric cancer cells. Also, the induction of apoptosis involved the intrinsic pathways of the cells. Take the results, we suggest that G. thunbergii extract has anti-gastric cancer activity and may be a potential therapeutic candidate for gastric cancer.

TRAIL-induced variation of cell signaling states provides nonheritable resistance to apoptosis

TNFα-related apoptosis-inducing ligand (TRAIL), specifically initiates programmed cell death, but often fails to eradicate all cells, making it an ineffective therapy for cancer. This fractional killing is linked to cellular variation that bulk assays cannot capture. Here, we quantify the diversity in cellular signaling responses to TRAIL, linking it to apoptotic frequency across numerous cell systems with single-cell mass cytometry (CyTOF). Although all cells respond to TRAIL, a variable fraction persists without apoptotic progression. This cell-specific behavior is nonheritable where both the TRAIL-induced signaling responses and frequency of apoptotic resistance remain unaffected by prior exposure. The diversity of signaling states upon exposure is correlated to TRAIL resistance. Concomitantly, constricting the variation in signaling response with kinase inhibitors proportionally decreases TRAIL resistance. Simultaneously, TRAIL-induced de novo translation in resistant cells, when blocked by cycloheximide, abrogated all TRAIL resistance. This work highlights how cell signaling diversity, and subsequent translation response, relates to nonheritable fractional escape from TRAIL-induced apoptosis. This refined view of TRAIL resistance provides new avenues to study death ligands in general.

Potential of Engineered Bacteriorhodopsins as Photoactivated Biomaterials in Modulating Neural Stem Cell Behavior

Bacteriorhodopsin (BR), a light-sensitive bacterial proton pump, has been demonstrated the capacity for regulating the neural activity in mammalian cells. Because of the difficulty in production and purification in large quantities, the BR proteins have neither been directly employed to biomedical applications nor verified the functionality by protein administration. Previously, we have invented a highly expressible bacteriorhodopsin (HEBR) and established the massive production protocol. In the current study, we mass-produced the two types of HEBR proteins that have normal or abnormal activity on the proton pumping, and then we treated murine neural stem cells (NSCs) with these HEBR proteins. We discovered that the cell behaviors including growth, metabolism, mitochondrial inner membrane potential, and differentiation were obviously affected in NSCs after the treatment of HEBR proteins. Particularly, these effects induced by HEBR proteins were correlated to their proton pump activity and could be altered by cell culture substrate materials. Current findings suggest that the engineered light-sensitive HEBR protein can serve as a biological material to directly influence the multiple behaviors of mammalian cells, which is further modified by the cell culture substrate material, revealing the versatile potential of HEBR protein in biomaterial applications.

In vitro cytotoxic and apoptotic induction effect of earthworm coelomic fluid of Eudrilus eugeniae, Eisenia foetida, and Perionyx excavatus on human oral squamous cell carcinoma-9 cell line

The current protocol of cancer management includes surgery, radiotherapy and chemotherapy. However, these modalities have significant adverse effects and affect the quality of life. Further intensification of treatment is hindered as maximal toxicity levels are reached impeding improvement. Hence researchers are in the quest for adjunctive naturally available therapies that can alter tumor proliferation without causing significant adverse reactions. The present study aims to explore the cytotoxic potential of earthworm coelomic fluid (ECF) of Eudrilus eugeniae (EE), Eisenia foetida (EF), and Perionyx excavatus (PE) on oral cancer cell line SCC-9. The effect of ECF on cell cycle analysis and mechanism of cell death have also been investigated. All experiments reported in this paper were performed as 3 replicates per experiment. The results indicated that ECF of EE, EF and PE have potent variable cytotoxic effect on SCC-9 cells demonstrated through LDH, clonogenic and comet assay. An effective cell cycle arrest was observed at the G2M phase of cell cycle with apoptotic induction that was observed through an Annexin V - FITC/PI assay. ECF of EE was found to be superior in its cytotoxic action closely followed by ECF of PE. The present findings provide evidence for the first time that ECF of EE, EF and PE have potent cytotoxic effect on oral cancer cells in vitro. They significantly induce G2M cell cycle arrest and promote apoptosis in SCC-9 cell line. Gene expression studies have been planned to ascertain the pathways of cell death.

A single-cell micro-trench platform for automatic monitoring of cell division and apoptosis after chemotherapeutic drug administration

Cells vary in their dynamic response to external stimuli, due to stochastic fluctuations and non-uniform progression through the cell cycle. Hence, single-cell studies are required to reveal the range of heterogeneity in their responses to defined perturbations, which provides detailed insight into signaling processes. Here, we present a time-lapse study using arrays of micro-trenches to monitor the timing of cell division and apoptosis in non-adherent cells at the single-cell level. By employing automated cell tracking and division detection, we precisely determine cell cycle duration and sister-cell correlations for hundreds of individual cells in parallel. As a model application we study the response of leukemia cells to the chemostatic drug vincristine as a function of cell cycle phase. The time-to-death after drug addition is found to depend both on drug concentration and cell cycle phase. The resulting timing and dose-response distributions were reproduced in control experiments using synchronized cell populations. Interestingly, in non-synchronized cells, the time-to-death intervals for sister cells appear to be correlated. Our study demonstrates the practical benefits of micro-trench arrays as a platform for high-throughput, single-cell time-lapse studies on cell cycle dependence, correlations and cell fate decisions in general.

Targeting Polo-like kinase 1 and TRAIL enhances apoptosis in non-small cell lung cancer

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can selectively induce apoptosis in cancer cells without causing damage to normal cells. However, some tumors are resistant to TRAIL monotherapy and clinical studies assessing targeted agents towards the TRAIL receptor have failed to show robust therapeutic activity. Evidence has shown that standard anti-mitotic drugs can induce synergistic apoptosis upon combination with TRAIL via cell cycle arrest. Polo like kinase-1 (PLK1) plays a critical role in different stages of cell cycle progression and mitosis. A number of investigations have demonstrated that PLK1 inhibition causes cell cycle arrest and mitotic catastrophe in non-small cell lung cancer (NSCLC), and we thus postulated that PLK1 inhibition could enhance TRAIL-induced apoptosis. We demonstrate that the combination of a TRAIL receptor agonist and a PLK1 inhibitor synergistically reduces cell viability, and strongly increases apoptosis in NSCLC cellular models. Consistent with our in vitro observations, this drug combination also significantly reduces tumor growth in vivo. Our data additionally reveal that G2/M cell cycle arrest and downregulation of Mcl-1 and signal transducer and activator of transcription 3 (STAT3) activity following PLK1 inhibition may contribute to the sensitization of TRAIL-induced apoptosis in NSCLC. Together, these data support the further exploration of combined TRAIL and PLK1 inhibition in the treatment of NSCLC.

An Antimicrobial Peptide Induces FIG1-Dependent Cell Death During Cell Cycle Arrest in Yeast

Although most antibiotics act on cells that are actively dividing and non-dividing cells such as in microbe sporulation or cancer stem cells represent a new paradigm for the control of disease. In addition to their relevance to health, such antibiotics may promote our understanding of the relationship between the cell cycle and cell death. No antibiotic specifically acting on microbial cells arrested in their cell cycle has been identified until the present time. In this study we used an antimicrobial peptide derived from α-pheromone, IP-1, targeted against MATa Saccharomyces cerevisiae cells in order to assess its dependence on cell cycle arrest to kill cells. Analysis by flow cytometry and fluorescence microscopy of various null mutations of genes involved in biological processes activated by the pheromone pathway (the mitogen-activated protein kinase pathway, cell cycle arrest, cell proliferation, autophagy, calcium influx) showed that IP-1 requires arrest in G₀/G₁ in order to kill yeast cells. Isolating cells in different cell cycle phases by elutriation provided further evidence that entry into cell cycle arrest, and not into G₁ phase, is necessary if our peptide is to kill yeast cells. We also describe a variant of IP-1 that does not activate the pheromone pathway and consequently does not kill yeast cells that express the pheromone’s receptor; the use of this variant peptide in combination with different cell cycle inhibitors that induce cell cycle arrest independently of the pheromone pathway confirmed that it is cell cycle arrest that is required for the cell death induced by this peptide in yeast. We show that the cell death induced by IP-1 differs from that induced by α-pheromone and depends on FIG1 in a way independent of the cell cycle arrest induced by the pheromone. Thus, IP-1 is the first molecule described that specifically kills microbial cells during cell cycle arrest, a subject of interest beyond the process of mating in yeast cells. The experimental system described in this study should be useful in the study of the mechanisms at play in the communication between cell cycle arrest and cell death on other organisms, hence promoting the development of new antibiotics.

Activation of the NF-κB pathway alters the phenotype of MSCs in the tracheal aspirates of preterm infants with severe BPD

Mesenchymal stromal cells (MSCs) are released into the airways of preterm infants following lung injury. These cells display a proinflammatory phenotype and are associated with development of severe bronchopulmonary dysplasia (BPD). We aimed to characterize the functional properties of MSCs obtained from tracheal aspirates of 50 preterm infants who required invasive ventilation. Samples were separated by disease severity. The increased proliferative capacity of MSCs was associated with longer duration of mechanical ventilation and higher severity of BPD. Augmented growth depended on nuclear accumulation of NFκBp65 and was accompanied by reduced expression of cytosolic α-smooth muscle actin (α-SMA). The central role of NF-κB signaling was confirmed by inhibition of IκBα phosphorylation. The combined score of proliferative capacity, accumulation of NFκBp65, and expression of α-SMA was used to predict the development of severe BPD with an area under the curve (AUC) of 0.847. We mimicked the clinical situation in vitro, and stimulated MSCs with IL-1β and TNF-α. Both cytokines induced similar and persistent changes as was observed in MSCs obtained from preterm infants with severe BPD. RNA interference was employed to investigate the mechanistic link between NFκBp65 accumulation and alterations in phenotype. Our data indicate that determining the phenotype of resident pulmonary MSCs represents a promising biomarker-based approach. The persistent alterations in phenotype, observed in MSCs from preterm infants with severe BPD, were induced by the pulmonary inflammatory response. NFκBp65 accumulation was identified as a central regulatory mechanism. Future preclinical and clinical studies, aimed to prevent BPD, should focus on phenotype changes in pulmonary MSCs.

Ponatinib promotes a G1 cell-cycle arrest of merlin/NF2-deficient human schwann cells

Neurofibromatosis type 2 (NF2) is a genetic syndrome that predisposes individuals to multiple benign tumors of the central and peripheral nervous systems, including vestibular schwannomas. Currently, there are no FDA approved drug therapies for NF2. Loss of function of merlin encoded by the NF2 tumor suppressor gene leads to activation of multiple mitogenic signaling cascades, including platelet-derived growth factor receptor (PDGFR) and SRC in Schwann cells. The goal of this study was to determine whether ponatinib, an FDA-approved ABL/SRC inhibitor, reduced proliferation and/or survival of merlin-deficient human Schwann cells (HSC). Merlin-deficient HSC had higher levels of phosphorylated PDGFRα/β, and SRC than merlin-expressing HSC. A similar phosphorylation pattern was observed in phospho-protein arrays of human vestibular schwannoma samples compared to normal HSC. Ponatinib reduced merlin-deficient HSC viability in a dose-dependent manner by decreasing phosphorylation of PDGFRα/β, AKT, p70S6K, MEK1/2, ERK1/2 and STAT3. These changes were associated with decreased cyclin D1 and increased p27^Kip1levels, leading to a G₁ cell-cycle arrest as assessed by Western blotting and flow cytometry. Ponatinib did not modulate ABL, SRC, focal adhesion kinase (FAK), or paxillin phosphorylation levels. These results suggest that ponatinib is a potential therapeutic agent for NF2-associated schwannomas and warrants further in vivo investigation.

Discovery and characterization of Isofistularin-3, a marine brominated alkaloid, as a new DNA demethylating agent inducing cell cycle arrest and sensitization to TRAIL in cancer cells

We characterized the brominated alkaloid Isofistularin-3 (Iso-3), from the marine sponge Aplysina aerophoba, as a new DNA methyltransferase (DNMT)1 inhibitor. Docking analysis confirmed our in vitro DNMT inhibition data and revealed binding of Iso-3 within the DNA binding site of DNMT1. Subsequent increased expression of tumor suppressor gene aryl hydrocarbon receptor (AHR) could be correlated to decreased methylation of CpG sites within the essential Sp1 regulatory region of its promoter. Iso-3 induced growth arrest of cancer cells in G0/G1 concomitant with increased p21 and p27 expression and reduced cyclin E1, PCNA and c-myc levels. Reduced proliferation was accompanied by morphological changes typical of autophagy revealed by fluorescent and transmission electron microscopy and validated by LC3I-II conversion. Furthermore, Iso-3 strongly synergized with tumor-necrosis-factor related apoptosis inducing ligand (TRAIL) in RAJI [combination index (CI) = 0.22] and U-937 cells (CI = 0.21) and increased TRAIL-induced apoptosis via a mechanism involving reduction of survivin expression but not of Bcl-2 family proteins nor X-linked inhibitor of apoptosis protein (XIAP). Iso-3 treatment decreased FLIP_L expression and triggered activation of endoplasmatic reticulum (ER) stress with increased GRP78 expression, eventually inducing TRAIL receptor death receptor (DR)5 surface expression. Importantly, as a potential candidate for further anticancer drug development, Iso-3 reduced the viability, colony and in vivo tumor forming potential without affecting the viability of PBMCs from healthy donors or zebrafish development.

N-terminal gelsolin fragment potentiates TRAIL mediated death in resistant hepatoma cells

TNF-α related apoptosis-inducing ligand (TRAIL) selectively kills tumor cells, without damaging normal cells. TRAIL receptors facilitate induction of apoptosis for selective elimination of malignant cells. However, some cancer cells have developed resistances to TRAIL which limits anticancer potential. Gelsolin, a multifunctional actin-binding protein, mediates cell death involving the TRAIL receptors in the hepatic stellate cell line, LX2. Here, we have shown that conditioned medium (CM) containing gelsolin fragments or an N-terminal gelsolin fragment (amino acid residues 1-70) in the presence of TRAIL impairs cell viability of TRAIL resistant transformed human hepatocytes (HepG2). Cell growth regulation by CM and TRAIL was associated with the modulation of p53/Mdm2, Erk and Akt phosphorylation status. The use of N-terminal gelsolin peptide1-70 alone or in combination with TRAIL, induced inhibition of Akt phosphorylation and key survival factors, Mdm2 and Survivin. Treatment of cells with an Akt activator SC79 or p53 siRNA reduced the effects of the N-terminal gelsolin fragment and TRAIL. Together, our study suggests that the N-terminal gelsolin fragment enhances TRAIL-induced loss of cell viability by inhibiting phosphorylation of Akt and promoting p53 function, effecting cell survival.

cFLIP critically modulates apoptotic resistance in epithelial-to-mesenchymal transition

Epithelial cancers (carcinomas) comprise the top four causes of cancer-related deaths in the United States. While overall survival has been steadily improving, therapy-resistant disease continues to present a major therapeutic challenge. Carcinomas often exploit the normal developmental program, epithelial-to-mesenchymal transition (EMT), to gain a mesenchymal phenotype associated with increased invasiveness and resistance to apoptosis. We have previously shown that an isoxazole-based small molecule, ML327, partially reverses TGF-β-induced EMT in an immortalized mouse mammary epithelial cell line. Herein, we demonstrate that ML327 reverses much of the EMT gene expression program in cultured carcinoma cell lines. The reversal of EMT sensitizes these cancer cells to the apoptosis-inducing ligand TRAIL. This sensitization is independent of E-cadherin expression and rather relies on the downregulation of a major anti-apoptotic protein, cFLIP_S. Loss of cFLIP_S is sufficient to overcome resistance to TRAIL and exogenous overexpression of cFLIP_S restores resistance to TRAIL-induced apoptosis despite EMT reversal with ML327. In summary, we have utilized an isoxazole-based small molecule that partially reverses EMT in carcinoma cells to demonstrate that cFLIP_S critically regulates the apoptosis resistance phenotype associated with EMT.

Peritoneal expression of Matrilysin helps identify early post-operative recurrence of colorectal cancer

Recurrence of colorectal cancer (CRC) following a potentially curative resection is a challenging clinical problem. Matrix metalloproteinase-7 (MMP-7) is over-expressed by CRC cells and supposed to play a major role in CRC cell diffusion and metastasis. MMP-7 RNA expression was assessed by real-time PCR using specific primers in peritoneal washing fluid obtained during surgical procedure. After surgery, patients underwent a regular follow up for assessing recurrence. transcripts for MMP-7 were detected in 31/57 samples (54%). Patients were followed-up (range 20-48 months) for recurrence prevention. Recurrence was diagnosed in 6 out of 55 patients (11%) and two patients eventually died because of this. Notably, all the six patients who had relapsed were positive for MMP-7. Sensitivity and specificity of the test were 100% and 49% respectively. Data from patients have also been corroborated by computational approaches. Public available coloncarcinoma datasets have been employed to confirm MMP7 clinical impact on the disease. Interestingly, MMP-7 expression appeared correlated to Tgfb-1, and correlation of the two factors represented a poor prognostic factor. This study proposes positivity of MMP-7 in peritoneal cavity as a novel biomarker for predicting disease recurrence in patients with CRC.

Nanoparticle-Mediated Target Delivery of TRAIL as Gene Therapy for Glioblastoma

Human tumor necrosis factor α-related apoptosis-inducing ligand (TRAIL) is an attractive cancer therapeutic because of its ability to induce apoptosis in tumor cells while having a negligible effect on normal cells. However, the short serum half-life of TRAIL and lack of efficient in vivo administration approaches have largely hindered its clinical use. Using nanoparticles (NPs) as carriers in gene therapy is considered as an alternative approach to increase TRAIL delivery to tumors as transfected cells would be induced to secrete TRAIL into the tumor microenvironment. To enable effective delivery of plasmid DNA encoding TRAIL into glioblastoma (GBM), we developed a targeted iron oxide NP coated with chitosan-polyethylene glycol-polyethyleneimine copolymer and chlorotoxin (CTX) and evaluated its effect in delivering TRAIL in vitro and in vivo. NP-TRAIL successfully delivers TRAIL into human T98G GBM cells and induces secretion of 40 pg mL(-1) of TRAIL in vitro. Transfected cells show threefold increased apoptosis as compared to the control DNA bound NPs. Systemic administration of NP-TRAIL-CTX to mice bearing T98G-derived flank xenografts results in near-zero tumor growth and induces apoptosis in tumor tissue. Our results suggest that NP-TRAIL-CTX can potentially serve as a targeted anticancer therapeutic for more efficient TRAIL delivery to GBM.

Inhibitor of apoptosis proteins as intracellular signaling intermediates

Inhibitor of apoptosis (IAP) proteins have often been considered inhibitors of cell death due to early reports that described their ability to directly bind and inhibit caspases, the primary factors that implement apoptosis. However, a greater understanding is evolving regarding the vital roles played by IAPs as transduction intermediates in a diverse set of signaling cascades associated with functions ranging from the innate immune response to cell migration to cell-cycle regulation. In this review, we discuss the functions of IAPs in signaling, focusing primarily on the cellular IAP (c-IAP) proteins. The c-IAPs are important components in tumor necrosis factor receptor superfamily signaling cascades, which include activation of the NF-κB transcription factor family. As these receptors modulate cell proliferation and cell death, the involvement of the c-IAPs in these pathways provides an additional means of controlling cellular fate beyond simply inhibiting caspase activity. Additionally, IAP-binding proteins, such as Smac and caspases, which have been described as having cell death-independent roles, may affect c-IAP activity in intracellular signaling. Collectively, the multi-faceted functions and complex regulation of the c-IAPs illustrate their importance as intracellular signaling intermediates.

Triazole analog 1-(1-benzyl-5-(4-chlorophenyl)-1H-1,2,3-triazol-4-yl)-2-(4-bromophenylamino)-1-(4-chlorophenyl)ethanol induces reactive oxygen species and autophagy-dependent apoptosis in both in vitro and in vivo breast cancer models

Autophagy is considered as an important cell death mechanism that closely interacts with other common cell death programs like apoptosis. Critical role of autophagy in cell death makes it a promising, yet challenging therapeutic target for cancer. We identified a series of 1,2,3-triazole analogs having significant breast cancer inhibition property. Therefore, we attempted to study whether autophagy and apoptosis were involved in the process of cancer cell inhibition. The lead molecule, 1-(1-benzyl-5-(4-chlorophenyl)-1H-1,2,3-triazol-4-yl)-2-(4-bromophenylamino)-1-(4-chlorophenyl)ethanol (T-12) induced significant cell cycle arrest, mitochondrial membrane depolarization, apoptosis and autophagy in MCF-7 and MDA-MB-231 cells. T-12 increased reactive oxygen species and its inhibition by N-acetyl-L-cysteine protected breast cancer cells from autophagy and apoptosis. Autophagy inhibitor, 3-methyladenine abolished T-12 induced apoptosis, mitochondrial membrane depolarization and reactive oxygen species generation. This suggested that T-12 induced autophagy facilitated cell death rather than cell survival. Pan-caspase inhibition did not abrogate T-12 induced autophagy, suggesting that autophagy precedes apoptosis. In addition, T-12 inhibited cell survival pathway signaling proteins, Akt, mTOR and Erk1/2. T-12 also induced significant regression of tumor with oral dose of as low as 10mg/kg bodyweight in rat mammary tumor model without any apparent toxicity. In presence of reactive oxygen species inhibitor (N-acetyl-L-cysteine) and autophagy inhibitor (chloroquine), T-12 induced tumor regression was significantly decreased. In conclusion, T-12 is a potent inducer of autophagy-dependent apoptosis in breast cancer cells both in vitro and in vivo and can serve as an important lead in development of new anti-tumor therapy.

Effects of curine in HL-60 leukemic cells: cell cycle arrest and apoptosis induction

Curine is a natural alkaloid isolated from Chondrodendron platyphyllum and it has been reported that this alkaloid has vasodilatory and anti-inflammatory effects. The aim of this study is to analyze the cytotoxic effects of curine in cancer cell lines HL-60, K562, and HT-29, and in primary cultures of peripheral blood mononuclear cells (PBMC). Cells were treated with curine (from 3 to 15 µM) for 24 and 48 h. Cell viability was analyzed by the 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test and flow cytometry with propidium iodide (PI) assay. To assess the type of cell death induced in HL-60, the cell cycle, morphological, and biochemical alterations were analyzed, which were determined by differential staining with acridine orange/ethidium bromide, and annexin V/PI double-labeling and change in mitochondrial membrane potential assays. Curine demonstrated a potent cytotoxic effect on leukemic cell lines (HL-60 and K562). Its cytotoxic effects in HL-60 cells was related to plasma membrane damage and cell cycle arrest at the G1 phase from 43.4 ± 1.0 to 56.7 ± 1.4 % (p < 0.05). Curine (15 μM) also increased the apoptotic cells number by around 60 % in HL-60 cells and caused phosphatidylserine externalization, inducing about 57 % of apoptosis. Moreover, this alkaloid provoked 20 % of mitochondrial membrane depolarization. We conclude that curine presented a cytotoxic effect and induced apoptosis in HL-60 cells. Thus, it can be considered a promising pharmacological drug.

Prognostic significance of ligands belonging to tumour necrosis factor superfamily in acute lymphoblastic leukaemia

Altered activities of ligands belonging to tumour necrosis factor (TNF) superfamily, namely B-cell activating factor (BAFF), a proliferation-inducing ligand (APRIL) and apoptosis inducing ligand (TRAIL) were demonstrated in several haematological diseases including acute lymphoblastic leukaemia (ALL). BAFF, APRIL and TRAIL provide crucial survival signals to immature, naive and activated B cells. These ligands are capable of activating a broad spectrum of intracellular signalling cascades that can either induce apoptosis or protect from programmed cell death. BAFF and APRIL, which can directly activate the NF-κB pathway, have been identified as crucial survival factors for ALL cells. Here, we have analyzed serum BAFF, APRIL and TRAIL concentrations in 48 patients with newly diagnosed ALL and 44 healthy volunteers. The levels of APRIL and BAFF were significantly higher in ALL patients as compared to healthy volunteers. In contrast, concentrations of TRAIL were significantly lower in ALL patients. Moreover, following induction, the levels of APRIL, but not BAFF or TRAIL, were significantly lower in a group of patients with complete remission (CR) as compared to non-respondent (NR) ALL patients. Furthermore, we demonstrated statistically significant differences in concentrations of APRIL between CR MRD-negative and CR, MRD-positive ALL patients. Notably detection of higher concentrations of APRIL was associated with shorter leukaemia-free survival and overall survival. Altogether, our data indicate that APRIL can play an important role in the pathogenesis of ALL and the measurement of APRIL levels can improve prognostication in ALL patients.

Plasmodium infection reduces the volume of the viral reservoir in SIV-infected rhesus macaques receiving antiretroviral therapy

Background

Previous studies indicated that Plasmodium infection activates the immune system, including memory CD4+ T cells, which constitute the reservoir of human immunodeficiency virus type-1 (HIV-1). Therefore, we postulated that co-infection with malaria might activate the reservoir of HIV-1. To test this hypothesis, we used a rhesus macaque model of co-infection with malaria and simian immunodeficiency virus (SIV), along with antiretroviral therapy (ART).

Results

Our results showed that Plasmodium infection reduced both the replication-competent virus pool in resting CD4+ T cells and the integrated virus DNA (iDNA) load in peripheral blood mononuclear cells in the monkeys. This reduction might be attributable to malaria-mediated activation and apoptotic induction of memory CD4+ T cells. Further studies indicated that histone acetylation and NF-kappaB (NF-κB) activation in resting CD4+ T cells may also play an important role in this reduction.

Conclusions

The findings of this work expand our knowledge of the interaction between these two diseases. As more HIV-1-infected individuals in malaria-endemic areas receive ART, we should explore whether any of the patients co-infected with Plasmodium experience virologic benefits.

Electronic supplementary material

The online version of this article (doi:10.1186/s12977-014-0112-x) contains supplementary material, which is available to authorized users.

Bortezomib sensitises TRAIL-resistant HPV-positive head and neck cancer cells to TRAIL through a caspase-dependent, E6-independent mechanism

Human papillomavirus (HPV) is causative for a new and increasing form of head and neck squamous cell carcinomas (HNSCCs). Although localised HPV-positive cancers have a favourable response to radio-chemotherapy (RT/CT), the impact of HPV in advanced or metastatic HNSCC remains to be defined and targeted therapeutics need to be tested for cancers resistant to RT/CT. To this end, we investigated the sensitivity of HPV-positive and -negative HNSCC cell lines to TRAIL (tumour necrosis factor-related apoptosis-inducing ligand), which induces tumour cell-specific apoptosis in various cancer types. A clear correlation was observed between HPV positivity and resistance to TRAIL compared with HPV-negative head and neck cancer cell lines. All TRAIL-resistant HPV-positive cell lines tested were sensitised to TRAIL-induced cell death by treatment with bortezomib, a clinically approved proteasome inhibitor. Bortezomib-mediated sensitisation to TRAIL was associated with enhanced activation of caspase-8, -9 and -3, elevated membrane expression levels of TRAIL-R2, cytochrome c release and G2/M arrest. Knockdown of caspase-8 significantly blocked cell death induced by the combination therapy, whereas the BH3-only protein Bid was not required for induction of apoptosis. XIAP depletion increased the sensitivity of both HPV-positive and -negative cells to TRAIL alone or in combination with bortezomib. In contrast, restoration of p53 following E6 knockdown in HPV-positive cells had no effect on their sensitivity to either single or combination therapy, suggesting a p53-independent pathway for the observed response. In summary, bortezomib-mediated proteasome inhibition sensitises previously resistant HPV-positive HNSCC cells to TRAIL-induced cell death through a mechanism involving both the extrinsic and intrinsic pathways of apoptosis. The cooperative effect of these two targeted anticancer agents therefore represents a promising treatment strategy for RT/CT-resistant HPV-associated head and neck cancers.

Molecular insights into the anti-cancer properties of traditional Tibetan medicine Yukyung Karne

BACKGROUND

Yukyung karne (YK) is a traditional Tibetan formulation used for many centuries for the treatment of ovarian cancer. However, the pharmacological basis of its anticancer property is not well understood. In the present study, the anticancer property of YK was investigated in cell culture.

METHODS

The growth inhibitory property of YK was evaluated in SKOV6, IHH, HepG2 and HEK293 cell lines using MTT assay. The pro-apoptotic activity of drug was analyzed by terminal deoxynuleotidyl transferase dUTP nick end labeling (TUNEL) and DNA fragmentation assays. Confocal microscopy was used to show the release of cytochrome c and its co-localization with mitochondria with the help of dsRed mitotracker in SKOV6 cells. The inhibition in cell proliferation was also visualized by confocal microscopy after BrDU incorporation. The activation of tumor suppressor p53 was evaluated by Western blotting while VEGF levels in culture supernatant were measured by a colorimetric method.

RESULTS

YK specifically and efficiently induced apoptotic killing of the human ovarian cancer SKOV6 cells as indicated by increased DNA fragmentation and nick end DNA labeling. Confocal microscopy suggested inhibition of cell proliferation and increase in cytochrome c release via perturbation in mitochondrial membrane potential (Δψm). Further, YK up-regulated the expression of tumor suppressor p53 and key cyclin-dependent kinase inhibitor p21, and inhibited VEGF secretion by cells. Interestingly, YK also exhibited a synergy with paclitaxel which is a well-known anti-cancer therapeutic drug.

CONCLUSIONS

The pharmacological properties of YK to impose growth arrest and trigger pro-apoptotic death in cells amply justify its usage in primary as well as adjunct therapy for ovarian cancer.

The ER stress inducer DMC enhances TRAIL-induced apoptosis in glioblastoma

Glioblastoma multiforme (GBM) is the most aggressive malignant brain tumour in humans and is highly resistant to current treatment modalities. We have explored the combined treatment of the endoplasmic reticulum (ER) stress-inducing agent 2,5-dimethyl-celecoxib (DMC) and TNF-related apoptosis-inducing ligand (TRAIL WT) or the DR5-specific TRAIL D269H/E195R variant as a potential new strategy to eradicate GBM cells using TRAIL-resistant and -sensitive GBM cells. GBM cell lines were investigated for their sensitivity to TRAIL, DMC and combination of both agents. Cell viability was measured by MTS assay and apoptosis was assessed by Annexin V/PI and acridine orange staining. Caspase activation and protein expression levels were analysed with Western blotting. Death Receptor (DR) cell surface expression levels were quantified by flow cytometry. DR5 expression was increased in U87 cells by ectopic expression using a retroviral plasmid and survivin expression was silenced using specific siRNAs. We demonstrate that A172 expresses mainly DR5 on the cell surface and that these cells show increased sensitivity for the DR5-specific rhTRAIL D269H/E195R variant. In contrast, U87 cells show low DR cell surface levels and is insensitive via both DR4 and DR5. We determined that DMC treatment displays a dose-dependent reduction in cell viability against a number of GBM cells, associated with ER stress induction, as shown by the up-regulation of glucose-regulated protein 78 (GRP78) and CCAAT/-enhancer-binding protein homologous protein (CHOP) in A172 and U87 cells. The dramatic decrease in cell viability is not accompanied by a correspondent increase in Annexin V/PI or caspase activation typically seen in apoptotic or/and necrotic cells within 24h of treatment. Although DMC did not affect DR5 expression in the GBM cells, it increased TRAIL-induced caspase-8 activation in both TRAIL-sensitive and -resistant cells, indicating that DMC potentiates initiator caspase activation in these cells. In A172 cells, sub-toxic concentrations of DMC greatly potentiated TRAIL-induced apoptosis. Furthermore, DMC strongly reduced survivin expression in A172 and U87 cells and silencing of this anti-apoptotic protein partially sensitized cells to TRAIL-induced apoptosis. Our findings corroborate that DMC is a promising agent against GBM, and uncovers a potential synergistic cooperation with TRAIL in this highly malignant cancer.

The multifunctional sorting protein PACS-2 regulates SIRT1-mediated deacetylation of p53 to modulate p21-dependent cell-cycle arrest

SIRT1 regulates the DNA damage response by deacetylating p53, thereby repressing p53 transcriptional output. Here, we demonstrate that the sorting protein PACS-2 regulates SIRT1-mediated deacetylation of p53 to modulate the DNA damage response. PACS-2 knockdown cells failed to efficiently undergo p53-induced cell-cycle arrest in response to DNA damage. Accordingly, p53 acetylation was reduced both in PACS-2 knockdown cells and thymocytes from Pacs-2(-/-) mice, thereby blunting induction of the cyclin-dependent kinase inhibitor p21 (CDKN1A). The SIRT1 inhibitor EX-527 or SIRT1 knockdown restored p53 acetylation and p21 induction as well as p21-dependent cell-cycle arrest in PACS-2 knockdown cells. Trafficking studies revealed that cytoplasmic PACS-2 shuttled to the nucleus, where it interacted with SIRT1 and repressed SIRT1-mediated p53 deacetylation. Correspondingly, in vitro assays demonstrated that PACS-2 directly inhibited SIRT1-catalyzed p53 deacetylation. Together, these findings identify PACS-2 as an in vivo mediator of the SIRT1-p53-p21 axis that modulates the DNA damage response.

A novel naproxen derivative capable of displaying anti-cancer and anti-migratory properties against human breast cancer cells

Background

Increasingly, the role of chronic inflammation and its mediators in tumor generation and progression is gaining importance in the field of cancer research. In this context, candidature of non steroidal anti-inflammatory drugs (NSAIDs) as potential anti-tumor therapeutic agent is being evaluated globally. In the present study we have evaluated the anti-cancer effect of a series of newly synthesized naproxen derivatives on human breast cancer cell lines.

Methods

MCF-7 (poorly invasive) and MDA-MB-231 (highly invasive) cells were treated with different concentrations of naproxen sodium and its derivatives in vitro, and the underlying mechanism of action was monitored by employing studies related to induction of apoptosis, activation of caspases, cell-cycle progression, synthesis of PGE₂ and cellular migration.

Results

After a preliminary screening using MCF-7 and MDA-MB-231 cells, it was evident that naproxen derivative 4 has a better killing property compared to its parent compound naproxen sodium (NS). On further investigation, it was apparent that the observed growth inhibitory activity on MDA-MB-231 cells after treatment with 4, was not due to cell cycle arrest but due to an early induction of apoptosis and subsequent induction of caspases 3 and 9. Derivative 4 could also inhibit COX activity in MDA-MB-231 cells as evidenced by reduction in prostaglandin E2 secretion. Moreover, 4 was capable of delaying the overall migration rate of MDA-MB-231 cells in vitro.

Conclusion

In this study we report that a naproxen-derivative (4) has powerful anti-inflammatory and anti-tumor properties as it induces appreciable amount of apoptosis in breast cancer cell line, and can also delay migration of cancer cells (MDA-MB-231) which would in turn delay cancer cell invasion and formation of secondary tumours in primary breast cancer patients. Thus, we propose that 4 is worthy of further investigation due to its potential as a therapeutic agent in anti-tumor treatment regimen.

Blockade of Death Ligand TRAIL Inhibits Renal Ischemia Reperfusion Injury

Renal ischemia-reperfusion injury (IRI) is a leading cause of acute kidney injury (AKI). Many investigators have reported that cell death via apoptosis significantly contributed to the pathophysiology of renal IRI. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor superfamily, and induces apoptosis and inflammation. However, the role of TRAIL in renal IRI is unclear. Here, we investigated whether TRAIL contributes to renal IRI and whether TRAIL blockade could attenuate renal IRI. AKI was induced by unilateral clamping of the renal pedicle for 60 min in male FVB/N mice. We found that the expression of TRAIL and its receptors were highly upregulated in renal tubular cells in renal IRI. Neutralizing anti-TRAIL antibody or its control IgG was given 24 hr before ischemia and a half-dose booster injection was administered into the peritoneal cavity immediately after reperfusion. We found that TRAIL blockade inhibited tubular apoptosis and reduced the accumulation of neutrophils and macrophages. Furthermore, TRAIL blockade attenuated renal fibrosis and atrophy after IRI. In conclusion, our study suggests that TRAIL is a critical pathogenic factor in renal IRI, and that TRAIL could be a new therapeutic target for the prevention of renal IRI.