Ruthenium(II) p-cymene complex bearing 2,2'-dipyridylamine targets caspase 3 deficient MCF-7 breast cancer cells without disruption of antitumor immune response

[Ru(η(6)-p-cym)Cl{dpa(CH2)4COOEt}][PF6] (cym=cymene; dpa=2,2'-dipyridylamine; complex 2) was prepared and characterized by elemental analysis, IR and multinuclear NMR spectroscopy, as well as ESI-MS and X-ray structural analysis. The structural analog without a side chain [Ru(η(6)-p-cym)Cl(dpa)][PF6] (1) as well as 2 were investigated in vitro against 518A2, SW480, 8505C, A253 and MCF-7 cell lines. Complex 1 is active against all investigated tumor cell lines while the activity of compound 2 is limited only to caspase 3 deficient MCF-7 breast cancer cells, however, both are less active than cisplatin. As CD4(+)Th cells are necessary to trigger all the immune effector mechanisms required to eliminate tumor cells, besides testing the in vitro antitumor activity of 1 and 2, the effect of ruthenium(II) complexes on the cells of the adaptive immune system have also been evaluated. Importantly, complex 1 applied in concentrations which were effective against tumor cells did not affect immune cell viability, nor did exert a general immunosuppressive effect on cytokine production. Thus, beneficial characteristics of 1 might contribute to the overall therapeutic properties of the complex.

Targeting LKB1 in cancer - exposing and exploiting vulnerabilities

The LKB1 tumour suppressor is a serine/threonine kinase that functions as master regulator of cell growth, metabolism, survival and polarity. LKB1 is frequently mutated in human cancers and research spanning the last two decades have begun decoding the cellular pathways deregulated following LKB1 inactivation. This work has led to the identification of vulnerabilities present in LKB1-deficient tumour cells. Pre-clinical studies have now identified therapeutic strategies targeting this subset of tumours that promise to benefit this large patient population harbouring LKB1 mutations. Here, we review the current efforts that are underway to translate pre-clinical discovery of therapeutic strategies targeting LKB1 mutant cancers into clinical practice.

In vitro effects of binuclear (η (6)-p-cymene)ruthenium(II) complex containing bridging bis(nicotinate)-polyethylene glycol ester ligand on differentiation pathways of murine Th lymphocytes activated by T cell mitogen

T cell differentiation into distinct T helper (Th) subpopulations is crucial in governing acquired immune responses as well as some inflammatory and autoimmune disorders. This study investigated potential of the novel neutral binuclear ruthenium(II) complexes 1-8 with general formula [{RuCl2(η(6)-p-cym)}2μ-(N(∩)N)] (N(∩)N = bis(nicotinate)- and bis(iso-nicotinate)-polyethylene glycol esters; (3-py)COO(CH2CH2O) n CO(3-py) and (4-py)COO(CH2CH2O) n CO(4-py); n = 1-4), as well as [RuCl2(η(6)-p-cym)(nic)] (R1, nic = nicotinate) and [RuCl2(η(6)-p-cym)(inic)] (R2, inic = isonicotinate) as an immunomodulatory agents capable to direct Th cell differentiation. From all investigated complexes, [{RuCl2(η(6)-p-cym)}2μ-{(3-py)COO(CH2CH2O)4CO(3-py)}] (4) was selected for further study because it did not affect splenocyte viability (in concentration up to 50 μM), but significantly reduced secretion of representative Th1 cytokine, IFN-γ induced by T cell mitogen. Besides IFN-γ, 4 inhibited dose dependently expression and production of representative Th17 cytokine, IL-17, in these cells. Otherwise, the production of anti-inflammatory cytokines IL-4 and IL-10 was upregulated. Also, 4 significantly increased CD4(+)CD25(+)FoxP3(+) Treg cell frequency in the activated splenocytes. Moreover, ConA-induced expression of Th1 transcription factors, T-bet and STAT1, as well as of Th17-related protein STAT3 was attenuated upon exposure to 4, while the expression of Th2-related transcription factor GATA3 remained stable. In conclusion, ruthenium(II) complex 4 modulates immune system cell functions in vitro by inhibiting T cell differentiation towards pathogenic Th1/Th17 phenotype and inducing a regulatory phenotype characterized by IL-10 and IL-4 production, which may provide novel therapeutic opportunities for immune-inflammatory and/or autoimmune disorders.

Strain difference in susceptibility to experimental autoimmune encephalomyelitis in rats correlates with T(H)1 and T(H)17-inducing cytokine profiles

Albino Oxford (AO) rats are resistant to induction of experimental autoimmune encephalomyelitis (EAE), in contrast to susceptible Dark Agouti (DA) rats. We have previously shown that draining lymph node cells (DLNC) obtained from immunized DA rats before the onset of the clinical disease produced more interferon (IFN)-gamma and interleukin (IL)-17 (signature cytokines of T(H)1 and T(H)17 responses, respectively) compared to DLNC from AO rats. In this study, we extend our analysis to entire induction phase of EAE with the emphasis on the T(H)1 and T(H)17-inducing cytokines. As a result, we show that throughout the inductive phase of the disease DLNC of DA rats, not only expressed higher levels of IFN-gamma and IL-17, but also of T(H)1-inducing cytokine-IL-12. As for T(H)17-inducing cytokines, DLNC of DA rats expressed more mRNA for p19, specific subunit of IL-23, but the expression of transforming growth factor (TGF)-beta in both strains was similar. Interestingly, the analysis of IL-6 expression revealed striking difference: while all DA DLNC were positive for IL-6 mRNA, cells from none of AO rats expressed detectable levels of mRNA for this cytokine. Taken together, our data suggest that the differential regulation of production of T(H)1 and T(H)17 cytokines, and IL-6 in particular, during the induction phase of disease could be responsible for the discrepancy in susceptibility to EAE between these two rat strains.

Murine brain endothelial cells differently modulate interferon-γ and interleukin-17 production in vitro

Brain endothelial cells (BEC) are the major constituents of the blood-brain barrier (BBB), the structure that controls entrance of immune cells into CNS parenchyma. Our aim was to investigate the influence of BEC on production of IL-17 and IFN-?-cytokines that are important for CNS inflammation. To that end, co-cultivations of the bEnd.3 brain endothelial cell line and lymph node cells (LNC) were performed, and gene expression and production of IL-17 and IFN-? were determined. It was found that bEnd.3 cells inhibited expression and production of IFN-?, but not of IL-17. Additionally, bEnd.3 cells also reduced production of the major IFN-?-promoting cytokine - IL-12 - in LNC. The observed variation in modulation of pro-inflammatory cytokines by BEC could be of importance for the understanding of CNS inflammation.

Macrophage migration inhibitory factor (MIF) is necessary for progression of autoimmune diabetes mellitus

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine of the innate immune system that plays a major role in the induction of immunoinflammatory responses. To examine the role of endogenous MIF in the pathogenesis of type 1 diabetes (TID) we evaluated the effects of administration of neutralizing anti-MIF antibodies to NOD mice with accelerated forms of diabetes induced by injection of cyclophosphamide or by transfer of diabetogenic spleen cells. Both accelerated forms of diabetes were markedly reduced by anti-MIF antibody. Furthermore, MIF-deficient (MIF(-/-)) mice were less susceptible to the induction of immunoinflammatory diabetes, insulitis and apoptosis within the endocrine pancreas by multiple low doses of streptozotocin (MLD-STZ) than genetically matched wild type (WT) mice. MIF deficiency resulted in lower proliferation and lymphocyte adhesion, as well as reduced production from the spleens and peritoneal cells of a variety of inflammatory mediators typically associated with development of the disease including IL-12, IL-23, TNF-alpha, and IL-1beta. Furthermore, MIF deletion affected the production of IL-18, TNF-alpha, IL-1beta, and iNOS in the islets of Langerhans. These data, along with the higher expression of IL-4 and TGF-beta observed in the periphery and in the pancreas of MLD-STZ-challenged MIF(-/-) mice as compared to WT controls suggest that MIF deficiency has induced an immune deviation towards protective type 2/3 response. These results suggest that MIF participates in T1D by controlling the functional activity of monocytes/macrophages and T cells and modulating their secretory capacity of pro- and anti-inflammatory molecules.

Astrocytes stimulate interleukin-17 and interferon-gamma production in vitro

Astrocytes play important roles in the complex and as yet not very well understood net of interactions among resident and infiltrating cells during central nervous system (CNS) inflammation. In such an intricate network, cytokines represent an essential means for intercellular communication, and astrocytes are able to affect their generation and/or release. Among various cytokines produced by infiltrating cells, interferon (IFN)-gamma and interleukin (IL)-17 are the focus of this research, because they are pivotal cytokines of helper T-cell type 1 (Th1) and helper T-cell type 17 (Th17), respectively. Importantly, both Th1 and Th17 cells, as well as their cytokines, have been shown to be of importance for the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model of a prototypical CNS disease with inflammatory pathogenesis, multiple sclerosis. Therefore, the influence of astrocytes on the generation of IFN-gamma and IL-17 in concanavalin A- and myelin basic protein-stimulated lymph node cells of healthy rats and rats with developing EAE, respectively, was investigated in vitro. Astrocytes up-regulated IL-17 and IFN-gamma gene expression and protein synthesis in T cells, which coincided with astrocytes' ability to express IL-23 subunit p19 and common IL-12/IL-23 subunit p40 but not IL-12 subunit p35 in the co-cultivations. These results suggest one more way in which astrocytes could contribute to the complex interactions during CNS inflammation.

A potent immunomodulatory compound, (S,R)-3-Phenyl-4,5-dihydro-5-isoxazole acetic acid, prevents spontaneous and accelerated forms of autoimmune diabetes in NOD mice and inhibits the immunoinflammatory diabetes induced by multiple low doses of streptozotocin in CBA/H mice

(S,R)-3-Phenyl-4,5-dihydro-5-isoxasole acetic acid (VGX-1027) is an isoxazole compound that exhibits various immunomodulatory properties. The capacity of VGX-1027 to prevent interleukin (IL)-1beta plus interferon-gamma-induced pancreatic islet death in vitro prompted us to evaluate its effects on the development of autoimmune diabetes in preclinical models of human type 1 diabetes mellitus (T1D). Administration of VGX-1027 to NOD mice with spontaneous or accelerated forms of diabetes induced either by injection of cyclophosphamide or by transfer of spleen cells from acutely diabetic syngeneic donors markedly reduced the cumulative incidence of diabetes and insulitis. In addition, VGX-1027 given either i.p. or p.o. to CBA/H mice made diabetic with multiple low doses of streptozotocin successfully counteracted the development of destructive insulitis and hyperglycemia. The animals receiving VGX-1027 exhibited reduced production of the proinflammatory mediators tumor necrosis factor-alpha, IL-1beta, macrophage migration inhibitory factor, and inducible nitric-oxide synthase-mediated nitric oxide generation in both pancreatic islets and peripheral compartments. These results indicate that VGX-1027 probably exerts its antidiabetogenic effects by limiting cytokine-mediated immunoinflammatory events, leading to inflammation and destruction of pancreatic islets. VGX-1027 seems worthy of being considered as a candidate drug in the development of new therapeutic strategies for the prevention and early treatment of T1D.

Strain difference in susceptibility to experimental autoimmune encephalomyelitis between Albino Oxford and Dark Agouti rats correlates with disparity in production of IL-17, but not nitric oxide

Albino Oxford (AO) rats, unlike Dark Agouti (DA) rats are resistant to the induction of experimental autoimmune encephalomyelitis (EAE). The reason for the resistance could be some restraining mechanism preventing auto-aggressive cell activation at the level of draining lymph nodes (DLN) during the induction phase of the disease. Such a mechanism could be anti-proliferative action of nitric oxide (NO), which has already been shown of importance for the resistance of several rat strains to the induction of the disease. Importantly, number of AO DLN cells (DLNC) is markedly lower and with lower proliferative response to myelin basic protein (MBP) ex vivo in comparison to DA DLNC in the inductive phase of EAE, thus implying that in AO rats DLNC do not proliferate as extensively as in DA rats. We show that AO rats do not produce larger quantities of NO than DA rats after immunization. Further, DLNC of immunized AO rats have significantly lower mRNA expression and synthesis of interferon (IFN)-gamma and interleukin (IL)-17 compared to DLNC of DA rats. Collectively, these results suggest that there is a substantial difference between EAE-resistant AO rats and EAE-prone DA rats in the initiation of autoimmune response. This difference seems to be independent of anti-proliferative actions of NO, but correlates with impaired IL-17 production in AO rats.

Interleukin-17 stimulates inducible nitric oxide synthase-dependent toxicity in mouse beta cells

The influence of the proinflammatory cytokine interleukin (IL)-17 on inducible nitric oxide (NO) synthase (iNOS)-mediated NO release was investigated in the mouse insulinoma cell line MIN6 and mouse pancreatic islets. IL-17 markedly augmented iNOS mRNA/protein expression and subsequent NO production induced in MIN6 cells or pancreatic islets by different combinations of interferon-gamma, tumor necrosis factor-alpha, and IL-1beta. The induction of iNOS by IL-17 was preceded by phosphorylation of p38 mitogen-activated protein kinase (MAPK), and inhibition of p38 MAPK activation completely abolished IL-17-stimulated NO release. IL-17 enhanced the NO-dependent toxicity of proinflammatory cytokines toward MIN6 cells, while IL-17-specific neutralizing antibody partially reduced the NO production and rescued insulinoma cells and pancreatic islets from NO-dependent damage induced by activated T cells. Finally, a significant increase in blood IL-17 levels was observed in a multiple low-dose streptozotocin model of diabetes, suggesting that T cell-derived IL-17 might be involved in NO-dependent damage of beta cells in this disease.

Aloe-emodin prevents cytokine-induced tumor cell death: the inhibition of auto-toxic nitric oxide release as a potential mechanism

Aloe-emodin (AE) is a plant-derived hydroxyanthraquinone with potential anticancer activity. We investigated the ability of AE to modulate survival of mouse L929 fibrosarcoma and rat C6 astrocytoma cells through interference with the activation of inducible nitric oxide (NO) synthase (NOS) and subsequent production of tumoricidal free radical NO. Somewhat surprisingly, AE in a dose-dependent manner rescued interferon-gamma + interleukin-1-stimulated L929 cells from NO-dependent killing by reducing their autotoxic NO release. The observed protective effect was less pronounced in C6 cells, due to their higher sensitivity to a direct toxic action of the drug. AE-mediated inhibition of tumor cell NO release coincided with a reduction in cytokine-induced accumulation of transcription and translation products of genes encoding inducible NOS and its transcription factor IRF-1, while activation of NF-kappaB remained unaltered. These data indicate that the influence of AE on tumor growth might be more complex that previously recognized, the net effect being determined by the balance between the two opposing actions of the drug: its capacity to directly kill tumor cells, but also to protect them from NO-mediated toxicity.