Development of an IL-6 antagonist peptide that induces apoptosis in 7TD1 cells

Ligand-Mediated Targeting of Cytokine Interleukin-27 Enhances Its Bioactivity In Vivo

We have examined the role of a novel targeted cytokine, interleukin-27 (IL-27), modified at the C terminus with a dual targeting and therapeutic heptapeptide, in treating prostate cancer. IL-27 has shown promise in halting tumor growth and mediating tumor regression in several cancer models, including prostate cancer. We describe our findings on the effects of targeted IL-27 gene delivery on prostate cancer cells in vitro and in vivo and how the targeting enhances bioactivity of the IL-27 cytokine. We applied the IL-27 gene delivery protocol utilizing sonoporation (sonodelivery) with the goal of reducing prostate tumor growth in an immunocompetent TC2R C57/BL6 model. The reduction in tumor growth and effector cellular profiles implicate targeted IL-27 as more effective than an untargeted version of IL-27 in promoting bioactivity, as assessed by STAT1 and IFN-γ reporter genes. Moreover, enhanced antitumor effects and significantly higher accumulation of natural killer T (NKT) and CD8 effector cells in the tumors were observed. These results support a novel IL-27-based targeting strategy that is promising since it shows improved therapeutic efficacy while utilizing simple and effective sonodelivery methods.

Interleukin-27 Gene Delivery Targeting IL-6Rα-Expressing Cells as a Stress Response Therapy

Interleukin-27 (IL-27) has shown promise in halting tumor growth and mediating tumor regression in several models, including prostate cancer. We describe our findings on the effects of IL-27 on the gene expression changes of TC2R prostate adenocarcinoma cells. We utilized RNAseq to assess profile differences between empty vector control, vector delivering IL-27 modified at its C-terminus with a non-specific peptide, and IL-27 modified at the C-terminus with a peptide targeting the IL-6-Rα. The targeted IL-27 had higher bioactivity and activity in vivo in a recent study by our group, but the mechanisms underlying this effect had not been characterized in detail at the gene expression level on tumor cells. In the present work, we sought to examine potential mechanisms for targeted IL-27 enhanced activity directly on tumor cells. The targeted IL-27 appeared to modulate several changes that would be consistent with an anti-tumor effect, including upregulation in the Interferon (IFN) and Interferon regulatory factor (IRF), oxidative phosphorylation, Janus kinase/Signal transducers and activators of transcription (JAK/STAT), and eukaryotic initiation factor 2 (EIF2) signaling. Of these signaling changes predicted by ingenuity pathway analyses (IPA), the novel form also with the highest significance (-log(Benjamini-Hochberg (B-H)) p-value) was the EIF2 signaling upregulation. We validated this predicted change by assaying for eukaryotic initiation factor 2 alpha (eIF2α), or phosphorylated eIF2α (p-eIF2α), and caspase-3 levels. We detected an increase in the phosphorylated form of eIF2α and in the cleaved caspase-3 fraction, indicating that the EIF2 signaling pathway was upregulated in these prostate tumor cells following targeted IL-27 gene delivery. This approach of targeting cytokines to enhance their activity against cancer cells is a novel approach to help augment IL-27's bioactivity and efficacy against prostate tumors and could be extended to other conditions where it could help interfere with the EIF2α pathway and promote caspase-3 activation.

Structure-based virtual screening and characterization of a novel IL-6 antagonistic compound from synthetic compound database

According to the three-dimensional (3D) complex structure of (hIL-6⋅hIL-6R⋅gp 130)₂ and the binding orientation of hIL-6, three compounds with high affinity to hIL-6R and bioactivity to block hIL-6 in vitro were screened theoretically from the chemical databases, including 3D-Available Chemicals Directory (ACD) and MDL Drug Data Report (MDDR), by means of the computer-guided virtual screening method. Using distance geometry, molecular modeling and molecular dynamics trajectory analysis methods, the binding mode and binding energy of the three compounds were evaluated theoretically. Enzyme-linked immunosorbent assay analysis demonstrated that all the three compounds could block IL-6 binding to IL-6R specifically. However, only compound 1 could effectively antagonize the function of hIL-6 and inhibit the proliferation of XG-7 cells in a dose-dependent manner, whereas it showed no cytotoxicity to SP2/0 or L929 cells. These data demonstrated that the compound 1 could be a promising candidate of hIL-6 antagonist.

Discovery and Characterization of a Potent Interleukin-6 Binding Peptide with Neutralizing Activity In Vivo

Interleukin-6 (IL-6) is an important member of the cytokine superfamily, exerting pleiotropic actions on many physiological processes. Over-production of IL-6 is a hallmark of immune-mediated inflammatory diseases such as Castleman's Disease (CD) and rheumatoid arthritis (RA). Antagonism of the interleukin IL-6/IL-6 receptor (IL-6R)/gp130 signaling complex continues to show promise as a therapeutic target. Monoclonal antibodies (mAbs) directed against components of this complex have been approved as therapeutics for both CD and RA. To potentially provide an additional modality to antagonize IL-6 induced pathophysiology, a peptide-based antagonist approach was undertaken. Using a combination of molecular design, phage-display, and medicinal chemistry, disulfide-rich peptides (DRPs) directed against IL-6 were developed with low nanomolar potency in inhibiting IL-6-induced pSTAT3 in U937 monocytic cells. Targeted PEGylation of IL-6 binding peptides resulted in molecules that retained their potency against IL-6 and had a prolongation of their pharmacokinetic (PK) profiles in rodents and monkeys. One such peptide, PN-2921, contained a 40 kDa polyethylene glycol (PEG) moiety and inhibited IL-6-induced pSTAT3 in U937 cells with sub-nM potency and possessed 23, 36, and 59 h PK half-life values in mice, rats, and cynomolgus monkeys, respectively. Parenteral administration of PN-2921 to mice and cynomolgus monkeys potently inhibited IL-6-induced biomarker responses, with significant reductions in the acute inflammatory phase proteins, serum amyloid A (SAA) and C-reactive protein (CRP). This potent, PEGylated IL-6 binding peptide offers a new approach to antagonize IL-6-induced signaling and associated pathophysiology.

Interleukin-6 subfamily cytokines and rheumatoid arthritis: role of antagonists

Many cytokines have been implicated in the inflammatory pathways that characterize rheumatoid arthritis (RA) and related inflammatory diseases of the joints. These include members of the interleukin-6 (IL-6) family of cytokines, several of which have been detected in excess in the synovial fluid from RA patients. What makes the IL-6 group of cytokines a family is their common use of the glycoprotein 130 (gp130) receptor subunit, to which they bind with different affinities. Several strategies have been developed to block the pro-inflammatory activities of IL-6 subfamily cytokines. These include the application of monoclonal antibodies, the creation of mutant form(s) of the cytokine with enhanced binding affinity to gp130 receptor and the generation of antagonists by selective mutagenesis of the specific cytokine/gp130 receptor-binding site(s). The rationale for the use of anti-cytokine therapy in inflammatory joint diseases is based on evidence from studies in vitro and in vivo, which implicate major cytokines such as interleukin-1 (IL-1), tumour necrosis factor (TNF)-alpha and IL-6 in RA pathogenesis. In particular, IL-6 subfamily antagonists have a wide range of potential therapeutic and research applications. This review focuses on the role of some of the IL-6 subfamily cytokines in the pathogenesis of the inflammatory diseases of the joints (IJDs), such as RA. In addition, an overview of the recently developed antagonists will be discussed.

Inhibition of IL-6-dependent growth of myeloma cells by an acidic peptide repressing the gp130-mediated activation of Src family kinases

An acidic domain (AD) of gp130 was previously found to interact with the Src family kinase (SFK) Hck. Here, the influence of myristoylated peptides derived from this AD was assessed in the mouse myeloma cell line, 7TD1. The IL-6-dependent growth of 7TD1 cells was reduced by approximately 75%, if 100 microM of myristoylated 18mer peptide (18AD) was included in the growth medium, but was unaffected by a control peptide with scrambled sequence (18sc). A similar differential inhibition by peptides 18AD and 18sc was observed for the erythropoietin-dependent growth of BaF-EH cells expressing chimeric erythropoietin receptor-gp130 and human Hck and for the human myeloma cell line INA-6. While the peptide 18AD concentration inhibiting 50% was approximately 30 microM in 7TD1 and BaF-EH cells, peptide 18AD did not significantly inhibit growth of IL-6-independent MM1.S myeloma and OKT1 hybridoma cells or of BaF-EH cells supplied with IL-3. Treatment with 100 microM peptide 18AD caused the same degree or 60% of apoptosis induction as IL-6 deprivation in 7TD1 or INA-6 cells, respectively. Co-immunoprecipitation experiments revealed that peptide 18AD interfered with the association of Hck and gp130 in 7TD1 lysates in a concentration-dependent manner. IL-6-treatment of INA-6 cells induced the kinase activities of Fyn, Lyn and Hck, but not Src, and the IL-6-induced SFK activities were inhibited by peptide 18AD. Expression in 7TD1 cells of a kinase-inactive Hck mutant (K269R) elicited a dominant-negative effect on cell number increases providing further evidence that SFKs are required for gp130 signalling in myeloma cells.

Interleukin-6 and new strategies for the treatment of cancer, hyperproliferative diseases and paraneoplastic syndromes

Interleukin-6 (IL-6) is a pleiomorphic cytokine whose growth factor properties play an important role in the development and progression of many types of cancer. IL-6 is produced in response to a variety of stimuli, and is required for the development of T and B lymphocytes to effector cells. In certain neoplasias, such as multiple myeloma, IL-6 is both produced and required for survival by the cancer cell itself. In other neoplasias, IL-6 may come from tissue surrounding the tumour. Thus, therapeutic strategies aimed at inhibiting the production, expression or action of IL-6 would be quite beneficial in the treatment of cancer. Moreover, IL-6 is a pathophysiological factor in several hyperproliferative diseases and the paraneoplastic syndromes that often accompany cancer, such as cachexia and osteoporosis; thus, anti-IL-6 therapy would be useful in treating these entities as well. This expert opinion acquaints the reader with IL-6, its physiological responses, the cancer types with which it is associated, and discusses the current state of therapy aimed at inhibiting it.

Structure-based design and characterization of a Novel IL-6 antagonist peptide

The development of rational methods to design antagonist peptides based on the 3-D structure of protein active region has, to now, been only marginally successful. This has been largely due to the difficulty of constraining the recognition elements of a mimetic structure to the relative conformational and spatial orientations present in the parent molecule. According to the 3-D complex structure of human interleukin-6 (hIL-6) and its receptor (hIL-6R), a novel antagonist peptide (named PT), which possessed potential bioactivity of hIL-6, was designed by the means of distance geometry, molecular modeling and molecular dynamics trajectory analysis. The bioactivity of the designed peptide (i.e. PT) was evaluated using XG-7 cells, a hIL-6-dependent B-cell line. PT possessed potential bioactivity to antagonize the function of hIL-6 and could efficiently induce the growth arrest and apoptosis of XG-7 cells in a dose-dependent manner.

A novel hIL-6 antagonist peptide from computer-aided design contributes to suppression of apoptosis in M1 cells

Based on the complex crystal structure of human interleukin-6 (hIL-6) and its receptor (hIL-6R), a novel hIL-6 antagonist peptide (named PT) was designed using computer-guided design method. Dealing with molecular docking and molecular dynamics methods, the interaction between PT and hIL-6R was analyzed. The theoretical studies showed that PT possessed very high affinity to hIL-6R and offered a practical means of imposing long-term blockade of hIL-6 activity in vivo. This effect was examined due to growth arrest and apoptosis induced by hIL-6 in myeloblastic cell line M1 cells in a dose-dependent manner. The findings demonstrate that PT could also act as an excellent antagonist candidate for the induction of growth arrest and apoptosis. Furthermore, murine M1 myeloid cell line, which was induced by the physiological inducer hIL-6 to undergo apoptosis and growth arrest, could be used as a subtle model system to test hIL-6 antagonist.

Effects of peptides, with emphasis on feeding, pain, and behavior A 5-year (1999-2003) review of publications in Peptides

Novel effects of naturally occurring peptides are continuing to be discovered, and their mechanisms of actions as well as interactions with other substances, organs, and systems have been elucidated. Synthetic analogs may have actions similar or antagonistic to the endogenous peptides, and both the native peptides and analogs have potential as drugs or drug targets. The journal Peptides publishes many leading articles on the structure-activity relationship of peptides as well as outstanding reviews on some families of peptides. Complementary to the reviews, here we extract information from the original papers published during the past five years in Peptides (1999-2003) to summarize the effects of different classes of peptides, their modulation by other chemicals and various pathophysiological states, and the mechanisms by which the effects are exerted. Special attention is given to peptides related to feeding, pain, and other behaviors. By presenting in condensed form the effects of peptides which are essential for systems biology, we hope that this summary of existing knowledge will encourage additional novel research to be presented in Peptides.