IL-10 elicits IFNγ-dependent tumor immune surveillance.

Tumor immune surveillance and cancer immunotherapies are thought to depend on the intratumoral infiltration of activated CD8(+) T cells. Intratumoral CD8(+) T cells are rare and lack activity. IL-10 is thought to contribute to the underlying immune suppressive microenvironment. Defying those expectations we demonstrate that IL-10 induces several essential mechanisms for effective antitumor immune surveillance: infiltration and activation of intratumoral tumor-specific cytotoxic CD8(+) T cells, expression of the Th1 cytokine interferon-γ (IFNγ) and granzymes in CD8(+) T cells, and intratumoral antigen presentation molecules. Consequently, tumor immune surveillance is weakened in mice deficient for IL-10 whereas transgenic overexpression of IL-10 protects mice from carcinogenesis. Treatment with pegylated IL-10 restores tumor-specific intratumoral CD8(+) T cell function and controls tumor growth.

Role of the TGF-beta/Alk5 signaling pathway in monocrotaline-induced pulmonary hypertension.

RATIONALE: Pulmonary arterial hypertension is a progressive disease characterized by an elevation in the mean pulmonary artery pressure leading to right heart failure and a significant risk of death. Alterations in two transforming growth factor (TGF) signaling pathways, bone morphogenetic protein receptor II and the TGF-beta receptor I, Alk1, have been implicated in the pathogenesis of pulmonary hypertension (PH). However, the role of TGF-beta family signaling in PH and pulmonary vascular remodeling remains unclear. OBJECTIVES: To determine whether inhibition of TGF-beta signaling will attenuate and reverse monocrotaline-induced PH (MCT-PH). METHODS: We have used an orally active small-molecule TGF-beta receptor I inhibitor, SD-208, to determine the functional role of this pathway in MCT-PH. MEASUREMENTS AND MAIN RESULTS: The development of MCT-PH was associated with increased vascular cell apoptosis, which paralleled TGF-beta signaling as documented by psmad2 expression. Inhibition of TGF-beta signaling with SD-208 significantly attenuated the development of the PH and reduced pulmonary vascular remodeling. These effects were associated with decreased early vascular cell apoptosis, adventitial cell proliferation, and matrix metalloproteinase expression. Inhibition of TGF-beta signaling with SD-208 in established MCT-PH resulted in a small but significant improvement in hemodynamic parameters and medial remodeling. CONCLUSIONS: These findings provide evidence that increased TGF-beta signaling participates in the pathogenesis of experimental severe PH.

Inhibition of p38alpha mitogen-activated protein kinase prevents the development of osteolytic bone disease, reduces tumor burden, and increases survival in murine models of multiple myeloma.

The bone microenvironment plays a critical role in supporting the growth and survival of multiple myeloma as well as in the development of osteolytic bone disease. Signaling through p38alpha mitogen-activated protein kinase (MAPK) mediates synthesis of multiple myeloma cell growth factors, and its inhibition reduces proliferation in vitro. However, it is unclear whether targeting p38alpha MAPK prevents multiple myeloma growth and the development of bone disease in vivo. In this study, we determined whether SCIO-469, a selective p38alpha MAPK inhibitor, inhibits multiple myeloma growth and prevents bone disease in the 5T2MM and 5T33MM models. SCIO-469 decreased constitutive p38alpha MAPK phosphorylation of both 5T2MM and 5T33MM cells in vitro. This was associated with decreased DNA synthesis and an induction of apoptosis when the cells were cultured with bone marrow stromal cells. Treatment of C57Bl/KaLwRij mice bearing 5T33MM cells with SCIO-469 inhibited p38alpha MAPK phosphorylation and was associated with a significant decrease in serum paraprotein, an almost complete reduction in tumor cells in the bone marrow, a decrease in angiogenesis, and a significant increase in disease-free survival. Injection of 5T2MM murine myeloma cells into C57Bl/KaLwRij mice resulted in myeloma bone disease characterized by increased osteoclast occupation of the bone surface, reduced cancellous bone, and the development of osteolytic bone lesions. Treatment of 5T2MM-injected mice with SCIO-469 reduced this development of bone disease. Together, these data show that targeting p38alpha MAPK with SCIO-469 decreases myeloma burden in vivo, in addition to preventing the development of myeloma bone disease.

Inhibition of growth and metastasis of mouse mammary carcinoma by selective inhibitor of transforming growth factor-beta type I receptor kinase in vivo.

PURPOSE: Transforming growth factor-beta (TGF-beta) suppresses tumor development by inhibiting cellular proliferation, inducing differentiation and apoptosis, and maintaining genomic integrity. However, once tumor cells escape from the tumor-suppressive effects of TGF-beta, they often constitutively overexpress and activate TGF-beta, which may promote tumor progression by enhancing invasion, metastasis, and angiogenesis and by suppressing antitumor immunity. The purpose of this study was to test this hypothesis using TGF-beta pathway antagonists. EXPERIMENTAL DESIGN: We examined the effects of selective TGF-beta type I receptor kinase inhibitors, SD-093 and SD-208, on two murine mammary carcinoma cell lines (R3T and 4T1) in vitro and in vivo. RESULTS: Both agents blocked TGF-beta-induced phosphorylation of the receptor-associated Smads, Smad2 and Smad3, in a dose-dependent manner, with IC50 between 20 and 80 nmol/L. TGF-beta failed to inhibit growth of these cell lines but stimulated epithelial-to-mesenchymal transdifferentiation, migration, and invasiveness into Matrigel in vitro. These effects were inhibited by SD-093, indicating that these processes are partly driven by TGF-beta. Treatment of syngeneic R3T or 4T1 tumor-bearing mice with orally given SD-208 inhibited primary tumor growth as well as the number and size of metastases. In contrast, SD-208 failed to inhibit R3T tumor growth or metastasis in athymic nude mice. Moreover, in vitro anti-4T1 cell cytotoxic T-cell responses of splenocytes from drug-treated animals were enhanced compared with cells from control animals. In addition, SD-208 treatment resulted in a decrease in tumor angiogenesis. CONCLUSION: TGF-beta type I receptor kinase inhibitors hold promise as novel therapeutic agents for metastatic breast cancer.

A novel peroxisome proliferator-activated gamma (PPAR gamma) agonist, CLX-0921, has potent antihyperglycemic activity with low adipogenic potential.

Agonists of the nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR gamma) are pharmacologically active antihyperglycemic agents that act by increasing peripheral tissue sensitivity to insulin. Many of these agonists have antihyperglycemic activity that is directly proportional to their ability to bind and activate PPAR gamma; however, recent data bring this relationship into question. In this report we describe a new PPAR gamma agonist, CLX-0921, that is derived from a natural product. This thiazolidinedione (TZD) has a spectrum of activity that differs from commercially available TZDs. It is a weak activator of PPAR gamma (EC(50) of 0.284 micromol/L) compared to rosiglitazone (EC(50) 0.009 micromol/L). Despite this difference, the drug maintains potent glucose uptake activity in vitro and glucose-lowering activity in vivo that is equipotent to that of rosiglitazone. Moreover, CLX-0921 showed a 10-fold reduction in in vitro adipogenic potential compared to rosiglitazone. CLX-0921 also increases glycogen synthesis, an activity not typically associated with rosiglitazone or pioglitazone. Thus CLX-0921 appears to have a distinct spectrum of activity relative to other TZDs.

Inhibition of p38 MAP kinase activity enhances axonal regeneration.

Tumor necrosis factor alpha (TNF)-induced cellular signaling through the p38 mitogen-activated protein kinase (p38 MAPK) pathway plays a critical role in Wallerian degeneration and subsequent regeneration, processes that depend on Schwann cell (SC) activity. TNF dose-dependently induces Schwann cell and macrophage activation in vivo and apoptosis in primary SC cultures in vitro, while inhibition of p38 MAPK is thought to block these cellular processes. We show with Western blots that after sciatic nerve crush injury, phosphorylated p38 (p-p38) MAPK is significantly increased (P < 0.01) in distal nerve segments. In tissue sections, p38 co-localized immunohistochemically with activated Schwann cells (GFAP) and to a lesser degree with macrophages (ED-1). In other experiments, animals were gavaged with Scios SD-169 (10 or 30 mg/kg) or excipient (PEG300) 1 day before and daily after crush injury to the sciatic nerve. SD-169 is a proprietary oral inhibitor of p38 MAPK activity. The rate of axonal regeneration was determined by the functional pinch test and was significantly increased in treated animals 8 days after crush injury (P < 0.05; 30 mg/kg dose). In SD-169-treated animals with nerve transection, nerve fibers regenerating through a silicone chamber were morphologically more mature than untreated nerves when observed 28 days after transection. TNF immunofluorescence of distal nerve segments after crush injury suggested that SD-169 reduced SC TNF protein. In support of these findings, SD-169 significantly reduced (P < 0.05) TNF-mediated primary SC death in culture experiments. We conclude that inhibition of p38 activity promotes axonal regeneration through interactions with SC signaling and TNF activity.