Summary To metastasize, a tumor cell must acquire abilities such as the capacity to colonize new tissue and evade immune surveillance. Recent evidence suggests that microRNAs can promote the evolution of malignant behaviors by regulating multiple targets. We performed a microRNA analysis of human melanoma, a highly invasive cancer, and found that miR-30b/30d upregulation correlates with stage, metastatic potential, shorter time to recurrence and reduced overall survival. Ectopic expression of miR-30b/30d promoted the metastatic behavior of melanoma cells by directly targeting the GalNAc transferase GALNT7, resulted in increased synthesis of the immunosuppressive cytokine IL-10, and reduced immune cell activation and recruitment. These data support a key role of miR-30b/30d and GalNAc transferases in metastasis, by simultaneously promoting cellular invasion and immunosuppression.

Dendritic cells (DCs) are key regulators of the immune system; they capture antigens and then can either stimulate an immune response or induce tolerance. Our aim was to activate individual DC signaling pathways to regulate the immune response. We therefore expressed constitutive activators of mitogenactivated protein kinase (MAPK) pathways or the interferon pathway, together with tumor antigens, using lentivectors. Triggering of p38 activated IntroductionA major challenge in immunization for the treatment of cancer or persistent infectious disease is to overcome an immune system that has been down-regulated after prolonged antigen exposure. This will require the development of immunization reagents that are more potent immune stimulators. On the other hand, in autoimmune or allergic disease, or in the delivery of potentially immunogenic transgenes for gene therapy, it will be helpful to have a mechanism to down-regulate an antigen-specific immune response. Much research has targeted dendritic cells (DCs) for the induction of specific immunity or antigen-specific tolerance, because DCs regulate innate and adaptive immune responses. 1 DCs are widely distributed in peripheral tissues as immature DCs, exhibiting high phagocytic capacity but poor antigen presentation capacity. Antigen presentation by immature DCs results in T-cell anergy or tolerance. [2][3][4][5] After encountering pathogens, DCs undergo a maturation program resulting in up-regulation of major histocompatibility complex (MHC) molecules and costimulatory molecules such as cluster of differentiation (CD) 80, CD86, CD40 and intercellular adhesion molecule I (ICAM-I). Activated DCs also secrete cytokines such as interleukin-12 (IL-12), 6 critical for generation of a Th1 response, or IL-10, 7 critical for a Th2 response, and migrate to secondary lymphoid organs where they present antigens to T cells.DCs express a variety of pathogen pattern recognition receptors including the prototypical family of toll-like receptors (TLRs). A complex network of intracellular signaling molecules are recruited on TLR binding to pathogen structures through 2 adaptor proteins, MYD88 and TRIF, leading to the activation of several signaling pathways. 8 Combined evidence from use of inhibitors or knockout mice has implicated the p38 mitogen-activated protein kinase (MAPK) and the NF-kB pathways in DC activation and IL-12 secretion, 9-11 the extracellular signal-regulated kinase (ERK) pathway in IL-10 secretion, 12,13 and IRF-3 in IFN-␤ induction, contributing to DC maturation. 14,15 This suggests that stimulation of individual signaling pathways could generate either immunostimulatory or immunosuppressive DCs. In fact, it was recently shown that enhanced immune responses were achieved by overexpressing NF-kB-inducing kinase (NIK) in DCs using an adenovirus vector. NF-kB activation in the absence of other signaling pathways led to DC maturation and IL-12 secretion in DC cultures, and an increased immune response to the green fluorescent protein (GFP) transgene in the adenovi...

Embryo implantation induces formation of the decidua, a stromal cell-derived structure that encases the fetus and placenta. Using the mouse as a model organism, we have found that this tissue reaction prevents DCs stationed at the maternal/fetal interface from migrating to the lymphatic vessels of the uterus and thus reaching the draining lymph nodes. Strikingly, decidual DCs remained immobile even after being stimulated with LPS and exhibiting responsiveness to CCL21, the chemokine that drives DC entry into lymphatic vessels. An analysis of maternal T cell reactivity toward a surrogate fetal/placental antigen furthermore revealed that regional T cell responses toward the fetus and placenta were driven by passive antigen transport and thus the tolerogenic mode of antigen presentation that predominates when there is negligible input from tissue-resident DCs. Indeed, the lack of involvement of tissue-resident DCs in the T cell response to the fetal allograft starkly contrasts with their prominent role in organ transplant rejection. Our results suggest that DC entrapment within the decidua minimizes immunogenic T cell exposure to fetal/placental antigens and raise the possibility that impaired development or function of the human decidua, which unlike that of the mouse contains lymphatic vessels, might lead to pathological T cell activation during pregnancy.

When expressed in heterologous cells, the viral FLIP protein (vFLIP) of Kaposi's-sarcoma-associated herpesvirus (KSHV) has been reported both to block Fas-mediated apoptosis and to activate the NF-κB activation pathway by interaction with IκB kinase (IKK). In a yeast-two-hybrid screen, we identified IKKγ as an interacting partner of vFLIP. We expressed fragments of IKKγ in mammalian cells and bacteria, and identified the central CCR3/4 (amino acids 150-272) as the vFLIP binding region. To investigate the proteins interacting with vFLIP in a KSHV-infected primary effusion lymphoma (PEL) cell line, we immunoprecipitated vFLIP and identified four associated proteins by mass spectrometry: IKK components IKKα, β and γ, and the chaperone, Hsp90. Using gel filtration chromatography, we demonstrated that a single population of vFLIP in the cytoplasm of PEL cells co-eluted and co-precipitated with an activated IKK complex. An inhibitor of Hsp90, geldanamycin, inhibited IKK's kinase activity induced by vFLIP and killed PEL cells, suggesting that vFLIP activation of IKK contributes to PEL cell survival.