Field cancerization predisposes the upper aerodigestive tract mucosa to the formation of multiple primary tumors, when exposed to environmental carcinogens. Up-regulation of epidermal growth factor receptor occurs early in squamous cell carcinogenesis and is critical for the loss of growth control in a variety of human cancers, including head and neck squamous cell carcinomas. In these tumor cells in culture, epidermal growth factor receptor stimulation initiates signaling via persistent activation of selective STAT proteins. To determine the timing of Stat3 activation in head and neck carcinogenesis, we studied the expression and constitutive activation of Stat3 in tumors and normal mucosa from patients with head and neck cancer compared with mucosa from controls without cancer. Stat3 was up-regulated and constitutively activated in both primary human head and neck tumors as well as in normal mucosa from these cancer patients compared with control normal mucosa from patients without cancer. In vivo liposome-mediated gene therapy with a Stat3 antisense plasmid efficiently inhibited Stat3 activation, increased tumor cell apoptosis, and decreased Bcl-x L expression in a head and neck xenograft model. These findings provide evidence that constitutively activated Stat3 is an early event in head and neck carcinogenesis that contributes to the loss of growth control by an anti-apoptotic mechanism.

IntroductionRegulatory T cells (Tregs) represent a critical barrier to immunotherapy of tumors. Established tumors suppress immune responses against their own antigens, and Tregs are emerging as a key mechanism contributing to this state of functional unresponsiveness. 1 In murine models, host Tregs become activated within days of tumor implantation. 2 Once activated, Tregs are difficult to eliminate and serve to potently and dominantly inhibit otherwise effective immune responses against the tumor. 3 We have shown that Foxp3 ϩ Tregs in the draining lymph nodes of mouse tumors become highly activated by exposure to the immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO). 4,5 In tumor-draining lymph nodes (TDLNs), IDO is expressed by a specific subset of IDO-competent plasmacytoid dendritic cells (DCs). 6 The combination of these IDO-expressing pDCs and IDO-activated Tregs renders the local milieu in the TDLNs profoundly inhibitory for T-cell activation. 7 Tregs can be suppressive, but this is not a fixed and immutable attribute. Resting Tregs are not spontaneously suppressive, and require an activation step before they become functionally inhibitory. 8 Conversely, the suppressive phenotype of Tregs is plastic. When Foxp3 is artificially ablated in mature Tregs, the suppressor phenotype is converted to a proinflammatory, T helper-like phenotype that can participate in autoimmunity. 9 Likewise, Tregs exposed to certain inflammatory signals (eg, from activated DCs or TLR ligands) can lose their suppressor activity 10 and may alter their phenotype (be "reprogrammed") to resemble proinflammatory effector cells. [11][12][13] Thus, at least in these experimental models, Tregs show a significant degree of phenotypic plasticity and are susceptible to both activation and deactivation (reprogramming) by signals from their local microenvironment.However, it is not known whether this apparent plasticity of Tregs is of biologic relevance for tumor immunology. In the current study, we test the hypothesis that, under conditions of antigendriven T-cell response to tumors, IDO functions as a critical molecular "switch" in TDLNs, regulating the phenotype and functional activity of Tregs. We show that, when IDO is active, Tregs are maintained in their normal potently suppressive state; but when IDO is blocked, Tregs undergo an inflammation-induced, interleukin-6 (IL-6)-dependent conversion into a nonsuppressive, proinflammatory phenotype similar to T-helper-17 (TH17) cells. These findings position IDO as a previously unsuspected key molecular regulator of Treg phenotype and function in TDLNs. Methods Reagents, cell lines, and mouse strainsA complete list of reagents, 1-methyl-D-tryptophan (1MT) preparation, tumor cell lines, and all transgenic and knockout mouse strains is given in supplemental materials (available on the Blood website; see the Supplemental Materials link at the top of the online article). Animal studies were approved by the Institutional Animal Care and Use Committee of the Medical College of Georgia. Detail...

Oncolytic viruses (OVs) are tumor-selective, multi-mechanistic antitumor agents. They kill infected cancer and associated endothelial cells via direct oncolysis, and uninfected cells via tumor vasculature targeting and bystander effect. Multimodal immunogenic cell death (ICD) together with autophagy often induced by OVs not only presents potent danger signals to dendritic cells but also efficiently cross-present tumor-associated antigens from cancer cells to dendritic cells to T cells to induce adaptive antitumor immunity. With this favorable immune backdrop, genetic engineering of OVs and rational combinations further potentiate OVs as cancer vaccines. OVs armed with GM-CSF (such as T-VEC and Pexa-Vec) or other immunostimulatory genes, induce potent anti-tumor immunity in both animal models and human patients. Combination with other immunotherapy regimens improve overall therapeutic efficacy. Coadministration with a HDAC inhibitor inhibits innate immunity transiently to promote infection and spread of OVs, and significantly enhances anti-tumor immunity and improves the therapeutic index. Local administration or OV mediated-expression of ligands for Toll-like receptors can rescue the function of tumor-infiltrating CD8+ T cells inhibited by the immunosuppressive tumor microenvironment and thus enhances the antitumor effect. Combination with cyclophosphamide further induces ICD, depletes Treg, and thus potentiates antitumor immunity. In summary, OVs properly armed or in rational combinations are potent therapeutic cancer vaccines.

The skin contains readily accessible dendritic cells (DCs) with potent antigen presentation function and functional plasticity enabling the integration of antigen specificity with environmentally responsive immune control. Recent studies challenge the established paradigm of cutaneous immune function by suggesting that lymph node-resident DCs, rather than skin-derived DCs (sDCs), are responsible for eliciting T cell immunity against cutaneous pathogens including viral vectors. We show that cutaneous delivery of lentivirus results in direct transfection of sDCs and potent and prolonged antigen presentation. Further, sDCs are the predominant antigen-presenting cells for the induction of potent and durable CD8(+) T cell immunity. These results support the classical paradigm of cutaneous immune function and suggest that antigen presentation by sDCs contributes to the high potency of lentivector-mediated genetic immunization.