Tracking death dealing by Fas and TRAIL in lymphatic neoplastic disorders: pathways, targets, and therapeutic tools

The in vitro evaluation of antibacterial efficacy optimized with cellular apoptosis on multi-functional polyurethane sealers for the root canal treatment

To solve the high instances of failure caused by endodontic reinfection, herein, an improved root filling material was produced to meet the multi-functional demand of sealers for root canal therapy. In this study, polyurethane (PU)-based nanocomposites were prepared by loading bismuth oxide, hydroxyapatite and antibacterial agents, namely Ag₃PO₄ and ZnO nanoparticles, which were named CP-Ag and CP-Zn sealers, respectively. A parallel biological evaluation at bacterial and cellular levels was performed to determine the fate of the different components of the PU-based sealers. Furthermore, the composition of sealers was quantified by screening their antibacterial activity and apoptotic factors, considering the potential toxicity of the nanoparticles and high dosage of metals. The in vitro optimization investigation was conducted systematically against Streptococcus mutans and Staphylococcus aureus, including bacteriostatic and dynamic tests, and the expression of the B-cell lymphoma-2 gene family and caspase proteases in the mitochondria-mediated apoptotic pathway was evaluated using the commercial AH Plus® and Apexit® Plus sealers for comparison. Additionally, the physical properties and sealing ability of sealers were assessed. The results showed that all PU-based sealers could meet the requirements of ISO 6876:2012 for root canal sealing materials. Based on the evaluation system, CP-Zn sealers expressed longer lasting antibacterial activity and lower toxic effect on cells compared to CP-Ag sealers. Especially, the CP-Zn5 sealer exhibited selective antimicrobial efficacy and hypo-toxicity, which were better than that of the two commercial sealers. According to the two-dimensional and three-dimensional methods, the good sealing ability of the CP-Zn5 sealer is the same as the excellent filling characters of AH Plus, which adapts to irregular root canals.

High content screen for identifying small-molecule LC3B-localization modulators in a renal cancer cell line

Forms of selective autophagy have now been recognized to regulate flux in many intracellular processes. Specific pathways and functions have been identified for mitophagy, ERphagy, and other selective autophagies; yet there is no consensus in whether and how autophagy regulates protein maintenance in and around the nucleus. Such processes are of interest for potential degradation of DNA and nuclear envelope proteins in various disease states. The mechanistic details of such nucleus-related autophagic processes remain elusive due to the lack of chemical or genetic regulators to manipulate and follow the process in vitro. Here, we describe a high content screen from which we identified small chemical compounds that can modulate the localization of the autophagy marker MAP1LC3B (LC3) in renal carcinoma cells. We also describe a pipeline designed for the execution and analysis of high content screens. The chemical tools discerned from this screen will allow for the deeper exploration of the mechanism, regulation, and molecular targets of nuclear-localized LC3 in perturbed cellular states.

Restoring the switch for cancer cell death: Targeting the apoptosis signaling pathway

PURPOSE

The relevance of apoptosis to cancer development and pharmacologic agents that target this pathway in selected malignancies are described.

SUMMARY

Apoptosis is a tightly regulated biological process mediated by both proapoptotic (i.e., prodeath) and antiapoptotic (i.e., prosurvival) proteins. While apoptosis represents a well-established effector mechanism induced by conventional chemotherapy in many malignancies, the development of apoptosis-based targeted therapy is relatively new. The pharmacologic restoration of apoptotic functions, either by blocking the action of antiapoptotic proteins/regulators (e.g., through investigational therapies such as inhibitors of apoptosis proteins, SMAC [second mitochondria-derived activator of caspases] mimetics, MDM2 [murine double minute 2] antagonists) or by inducing apoptosis (e.g., through investigational agonistic monoclonal antibodies or fusion proteins), holds robust potential for cancer pharmacotherapy. Notably, BH domain 3 (BH3) mimetics, a new class of small molecules that block the action antiapoptotic proteins, are touted a success for apoptosis-based targeted therapy. Venetoclax, a synthetic peptide that belongs to this class of BH3 mimetics, is currently approved by the Food and Drug Administration for the treatment of relapsed/refractory chronic lymphocytic leukemia in patients with 17p deletion as a single agent. This agent has been increasingly used either alone or as part of combination therapy for diverse hematologic malignancies in clinical trials.

CONCLUSION

Advances in the understanding of molecular mechanisms of apoptosis have given rise to more-refined targeted therapies for diverse malignancies, with the goal to improve survival outcome while sparing treatment-related toxicities.

Hetero-oligomerization between the TNF receptor superfamily members CD40, Fas and TRAILR2 modulate CD40 signalling

TNF receptor superfamily members (TNFRSF) such as CD40, Fas and TRAIL receptor 2 (TRAILR2) participate to the adaptive immune response by eliciting survival, proliferation, differentiation and/or cell death signals. The balance between these signals determines the fate of the immune response. It was previously reported that these receptors are able to self-assemble in the absence of ligand through their extracellular regions. However, the role of this oligomerization is not well understood, and none of the proposed hypotheses take into account potential hetero-association of receptors. Using CD40 as bait in a flow cytometry Förster resonance energy transfer assay, TNFRSF members with known functions in B cells were probed for interactions. Both Fas and TRAILR2 associated with CD40. Immunoprecipitation experiments confirmed the interaction of CD40 with Fas at the endogenous levels in a BJAB B-cell lymphoma cell line deficient for TRAILR2. TRAILR2-expressing BJAB cells displayed a robust CD40–TRAILR2 interaction at the expense of the CD40–Fas interaction. The same results were obtained by proximity ligation assay, using TRAILR2-positive and -negative BJAB cells and primary human B cells. Expression of the extracellular domains of Fas or TRAILR2 with a glycolipid membrane anchor specifically reduced the intrinsic signalling pathway of CD40 in 293T cells. Conversely, BJAB cells lacking endogenous Fas or TRAILR2 showed an increased NF-κB response to CD40L. Finally, upregulation of TRAILR2 in primary human B cells correlated with reduced NF-κB activation and reduced proliferation in response to CD40L. Altogether, these data reveal that selective interactions between different TNFRSF members may modulate ligand-induced responses upstream signalling events.

Reactivation of dormant anti-tumor immunity - a clinical perspective of therapeutic immune checkpoint modulation

In favor of their outgrowth, cancer cells must resist immune surveillance and edit the immune response. Cancer immunoediting is characterized by fundamental changes in the cellular composition and the inflammatory cytokine profiles in the microenvironment of the primary tumor and metastatic niches, with an ever increasing complexity of interactions between tumor cells and the immune system. Recent data suggest that genetic instability and immunoediting are not necessarily disparate processes. Increasing mutational load may be associated with multiple neoepitopes expressed by the tumor cells and thus increased chances for the immune system to recognize and combat these cells. At the same time the immune system is more and more suppressed and exhausted by this process. Consequently, immune checkpoint modulation may have the potential to be most successful in genetically highly altered and usually extremely unfavorable types of cancer. Moreover, the fact that epitopes recognized by the immune system are preferentially encoded by passenger gene mutations opens windows of synergy in targeting cancer-specific signaling pathways by small molecules simultaneously with antibodies modifying T-cell activation or exhaustion.

This review covers some aspects of the current understanding of the immunological basis necessary to understand the rapidly developing therapeutic endeavours in cancer treatment, the clinical achievements made, and raises some burning questions for translational research in this field.

Human-gyrovirus-Apoptin triggers mitochondrial death pathway--Nur77 is required for apoptosis triggering

The human gyrovirus derived protein Apoptin (HGV-Apoptin) a homologue of the chicken anemia virus Apoptin (CAV-Apoptin), a protein with high cancer cells selective toxicity, triggers apoptosis selectively in cancer cells. In this paper, we show that HGV-Apoptin acts independently from the death receptor pathway as it induces apoptosis in similar rates in Jurkat cells deficient in either FADD (fas-associated death domain) function or caspase-8 (key players of the extrinsic pathway) and their parental clones. HGV-Apoptin induces apoptosis via the activation of the mitochondrial intrinsic pathway. It induces both mitochondrial inner and outer membrane permebilization, characterized by the loss of the mitochondrial potential and the release into cytoplasm of the pro-apoptotic molecules including apoptosis inducing factor and cytochrome c. HGV-Apoptin acts via the apoptosome, as lack of expression of apoptotic protease-activating factor 1 in murine embryonic fibroblast strongly protected the cells from HGV-Apoptin–induced apoptosis. Moreover, QVD-oph a broad-spectrum caspase inhibitor delayed HGV-Apoptin–induced death. On the other hand, overexpression of the anti-apoptotic BCL-XL confers resistance to HGV-Apoptin–induced cell death. In contrast, cells that lack the expression of the pro-apoptotic BAX and BAK are protected from HGV-Apoptin induced apoptosis. Furthermore, HGV-Apoptin acts independently from p53 signal but triggers the cytoplasmic translocation of Nur77. Taking together these data indicate that HGV-Apoptin acts through the mitochondrial pathway, in a caspase-dependent manner but independently from the death receptor pathway.

Critical signaling pathways in bone sarcoma: candidates for therapeutic interventions

Bone sarcomas cause disproportionate morbidity and mortality and desperately need new therapies as there has been little improvement in outcomes in 20 years. Identification of critical signaling pathways, including type 1 insulin-like growth factor receptor (IGF-1R) for Ewing sarcoma and possibly osteosarcoma, and the ERBB and the Wnt signaling pathways for osteosarcoma, have emerged as receptors mediating vital signals for bone sarcoma. Akt, mammalian target of rapamycin (mTOR), phosphoinositide 3-kinases, mitogen-activated protein kinase kinase, extracellular signal-regulated kinases, and Ras pathway play key roles in at least some tumors, and inhibition of mTOR in particular will likely lead to improved survival, although clinical trials are still underway. The Notch pathway and ezrin are essential for osteosarcoma metastasis, and Fas downregulation is necessary for survival of metastases in lungs. As little is known about chondrosarcoma signaling, more preclinical work is needed. By defining vital signaling pathways in bone sarcomas, small molecule inhibitors can be applied rationally, leading to longer survival and reducing morbidity and late effects from intensive chemotherapy.

Plasma membrane-focused proteomics: dramatic changes in surface expression during the maturation of human dendritic cells

The differential expression of surface molecules on dendritic cells (DC) reflects their functional differences as immature and mature subsets. It is difficult, however, to characterize differences in surface expression by standard proteomic approaches, due mainly to the hydrophobic nature and low abundance of the individual proteins in question. We have established a method for obtaining high-yield plasmalemma preparations which contain surface molecules enriched more than 200-fold by coating cells with beads conjugated with antibody against a cell type-specific cell-surface molecule, followed by nitrogen cavitated disruption, magnetic separation, and density gradient ultracentrifugation. We identified and quantified 339 human monocyte-derived DC transmembrane proteins, including 33 previously uncharacterized molecules. Whereas 106 proteins were selectively expressed in immature cells or down-regulated after maturation, 191 proteins were selectively expressed in mature cells or up-regulated after maturation.

Cancer-specific toxicity of apoptin is independent of death receptors but involves the loss of mitochondrial membrane potential and the release of mitochondrial cell-death mediators by a Nur77-dependent pathway

Apoptin, a small proline-rich protein derived from the chicken anaemia virus, induces cell death selectively in cancer cells. The signalling pathways of apoptin-induced, cancer cell-selective apoptosis are not well understood. Here, we demonstrate that apoptin triggers apoptosis by activating the mitochondrial/intrinsic pathway, and that it acts independently of the death receptor/extrinsic pathway. Jurkat cells deficient in either FADD or caspase-8 (which are both necessary for the extrinsic pathway) were equally as sensitive to apoptin as their parental clones. This demonstrates that apoptin is likely to act through the mitochondrial death pathway. Apoptin treatment causes a loss of mitochondrial membrane potential, and release of the mitochondrial proteins cytochrome c and apoptosis-inducing factor. Apoptin-induced cell death is counteracted by the anti-apoptotic Bcl-2 family members, Bcl-2 itself and Bcl-XL, as shown in Jurkat leukaemia cells. In addition, we describe the processing and activation of caspase-3. By contrast, cleavage of caspase-8, which is predominantly triggered by the death receptor pathway, is not observed. Furthermore, apoptin triggers the cytoplasmic translocation of Nur77, and the inhibition of Nur77 expression by siRNA significantly protects MCF7 cells from apoptin-triggered cell death. Thus, our data indicate that the apoptin death signal(s) ultimately converges at the mitochondria, and that it acts independently of the death receptor pathway.

Fas/FasL interaction: a novel immune therapy approach with immobilized biologicals

Systemically applied agents to modulate the Fas/FasL system, e.g., by stimulation of Fas on activated leukocytes or tumor cells failed as strategies in immune therapy due to severe toxic effects in the host. Recently, a novel strategy has been developed by using immobilized immune active biologicals in a medical device that may allow immune management without expensive systemic therapy. This review reports on the potential role of Fas/FasL in immune therapy and summarizes current experimental and clinical data with the leukocyte inhibition module (LIM), an immobilized anti-Fas antibody containing device yet used in extracorporeal blood circulation. This proof of principal may stimulate the development of other devices based on the regulation of Fas/FasL or other targets relevant for immune disorders.

Daxx overexpression in T-lymphoblastic Jurkat cells enhances caspase-dependent death receptor- and drug-induced apoptosis in distinct ways

The role of Daxx, in particular, its ability to promote or hinder apoptosis, still remains controversial. In order to elucidate the functional relevance of Daxx in apoptosis signaling of malignant lymphocytes, Jurkat T-cells were stably transfected with a Daxx-expressing vector or with the respective Daxx-negative control vector. We thus demonstrate that ectopic expression of Daxx substantially increases the rate of apoptosis upon incubation with death receptor agonists such as Fas and TRAIL as well as upon incubation with the cytotoxic drug doxorubicin (DOX). Analysis of the molecular changes induced in the extrinsic and intrinsic apoptosis pathways reveals that augmentation of apoptosis by Daxx overexpression is conveyed by distinctly different mechanisms. Although enforced apoptosis caused by ectopic Daxx expression is caspase-dependent in both cases, major differences between Fas/TRAIL-induced apoptosis and doxorubicin-induced apoptosis are observed in expression patterns of X-linked inhibitor of apoptosis (XIAP), p53, Bid, ZIP kinase, and prostate apoptosis response gene 4 (Par-4). Moreover, we could show that addition of a CD95 blocking antibody to the clones treated with doxorubicin was able to increase apoptosis as compared to doxorubicin treatment alone and was accompanied by an enhancement of the mitochondrial branch of apoptosis. In conclusion, we here outline the major molecular mechanisms underlying the apoptosis-promoting effect of Daxx in neoplastic lymphocytes and demonstrate fundamental molecular differences elicited by the overexpression of Daxx in the extrinsic and intrinsic signaling pathways.

Chimeric NK-receptor-bearing T cells mediate antitumor immunotherapy

NKG2D is an activating cell-surface receptor expressed on natural killer (NK) cells and some T-cell subsets. Its ligands are primarily expressed on tumor cells. The aim of this study was to determine whether chimeric NK-receptor-bearing T cells would directly kill tumor cells and lead to induction of host immunity against tumors. Chimeric NK receptors were produced by linking NKG2D or DNAX activating protein of 10 kDa (Dap10) to the cytoplasmic portion of the CD3zeta chain. Our results showed that chimeric (ch) NKG2D-bearing T cells responded to NKG2D-ligand-bearing tumor cells (RMA/Rae-1beta, EG7) but not to wild-type tumor cells (RMA). This response was dependent upon ligand expression on the target cells but not on expression of major histocompatibility complex (MHC) molecules, and the response could be blocked by anti-NKG2D antibodies. These T cells produced large amounts of T-helper 1 (Th1) cytokines and proinflammatory chemokines and killed ligand-expressing tumor cells. Adoptive transfer of chNKG2D-bearing T cells inhibited RMA/Rae-1beta tumor growth in vivo. Moreover, mice that had remained tumor-free were resistant to subsequent challenge with the wild-type RMA tumor cells, suggesting the generation of immunity against other tumor antigens. Taken together, our findings indicate that modification of T cells with chimeric NKG2D receptors represents a promising approach for immunotherapy against cancer.