Prostaglandin E2-dependent enhancement of tissue inhibitors of metalloproteinases-1 production limits dendritic cell migration through extracellular matrix.

Dendritic cell (DC) migration is crucial for the initiation of immune responses. The balance between metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) has been shown to modulate DC migration. PGE2, which is overproduced in a wide variety of human malignancies, has been implicated in MMP and TIMP regulation in various cells, including monocytes. In the present study, we hypothesized that tumor-derived PGE2 would affect DC migratory capacity through the extracellular matrix (ECM) by altering MMP and TIMP balance. Treatment of monocyte-derived immature DC with exogenous PGE2 induced TIMP-1 secretion but not MMP-9 production and was correlated with reduced DC migration through ECM. Because recombinant TIMP-1 replicated PGE2 inhibition of DC migration while anti-TIMP-1 neutralizing Ab reversed it, we conclude that PGE2-mediated induction of TIMP-1 was responsible for the reduced migration of PGE2-treated DC. Similarly, DC cultured for 48 h in supernatants from cyclooxygenase-2 overexpressing lung cancer cells that secrete high levels of PGE2, exhibited decreased migration through ECM. Finally, analysis of E prostanoid receptor expression and their selective inhibition revealed that the enhanced TIMP-1 secretion in PGE2-treated DC was mediated predominantly by the E prostanoid receptor 2. These findings indicate that PGE2-dependent enhancement of TIMP-1 production causes reduced migration of DC through ECM.

Cyclooxygenase-2 modulates the insulin-like growth factor axis in non-small-cell lung cancer.

Constitutive overexpression of cyclooxygenase-2 (COX-2) occurs frequently in several different malignancies, including lung, colon, breast, and prostate cancer. Clinical studies have established elevated serum insulin-like growth factor (IGF-I) content and IGF-I:IGF-binding protein 3 (IGFBP-3) ratio as risk factors for these same malignancies. Therefore, we sought to determine the link between COX-2 expression and the IGF axis in COX-2 gene-modified human non-small-cell lung cancer (NSCLC) cells. Overexpression of COX-2 in NSCLC cells enhanced the antiapoptotic and mitogenic effects of IGF-I and IGF-II, facilitated the autophosphorylation of the type 1 IGF receptor, increased class IA phosphatidylinositol 3'-kinase activity, and decreased expression of IGFBP-3. Thus, these findings show that COX-2 augments the stimulatory arm of the IGF axis.

Multifaceted roles of cyclooxygenase-2 in lung cancer.

Lung cancer is the leading cause of cancer death in the United States. Although the low 5-year survival rate (under 15%) has changed minimally in the last 25 years, new agents and combinations of agents that target tumor proliferation, invasion, and survival may lead to improvement in patient outcomes. There is evidence that cyclooxygenase-2 (COX-2) is overexpressed in lung cancer and promotes tumor proliferation, invasion, angiogenesis, and resistance to apoptosis. COX-2 inhibitors have been found to inhibit tumor growth in animal models and have demonstrated responses when combined with conventional therapy in phase II clinical trials. Further understanding of the mechanisms involved in COX-2-mediated tumorigenesis and its interaction with other molecules in lung cancer may lead to improved therapeutic strategies for this disease. In addition, delineation of how COX-2-dependent genes modulate the malignant phenotype will provide novel insights in lung cancer pathogenesis.

Intratumoral administration of dendritic cells overexpressing CCL21 generates systemic antitumor responses and confers tumor immunity.

To achieve in situ tumor antigen uptake and presentation, intratumoral administration of ex vivo-generated, gene-modified murine bone marrow-derived dendritic cells (DC) was used in a murine lung cancer model. To attract mature host DC and activated T cells at the tumor site, the DC were transduced with an adenoviral vector expressing secondary lymphoid tissue chemokine (CCL21/SLC). Sixty percent of the mice treated with 10(6) DC-AdCCL21 intratumorally (7-10 ng/ml/10(6) cells/24 h of CCL21) at weekly intervals for 3 weeks showed complete tumor eradication, whereas only 25% of mice had complete resolution of tumors when mice were treated with fibroblasts expressing CCL21. In contrast only 12% of the mice treated with unmodified or control vector modified DC (DC-AdCV) showed complete tumor eradication. DC-AdCCL21 administration led to increases in the CD4(+), CD8(+), and CD3(+)CXCR3(+) T cells, as well as DC expressing CD11c(+) DEC205(+). CD4(+)CD25(+) T-regulatory cells infiltrating the tumors were markedly reduced after DC-AdCCL21 therapy. The tumor site cellular infiltrates were accompanied by the enhanced elaboration of granulocyte macrophage colony-stimulating factor, IFN-gamma, MIG/CXCL9, IP-10/CXCL10, and interleukin 12, but decreases in the immunosuppressive mediators transforming growth factor beta and prostaglandin E(2). DC-AdCCL21-treated tumor-bearing mice showed enhanced frequency of tumor-specific T lymphocytes secreting IFN-gamma, and tumor protective immunity was induced after DC-AdCCL21 therapy. In vivo depletion of IP-10/CXCL10, MIG/CXCL9, or IFN-gamma significantly reduced the antitumor efficacy of DC-AdCCL21. These findings provide a strong rationale for the evaluation of DC-AdCCL21 in cancer immunotherapy.

Overexpression of CCL-21/secondary lymphoid tissue chemokine in human dendritic cells augments chemotactic activities for lymphocytes and antigen presenting cells.

BACKGROUND: Ex vivo generated dendritic cells (DC) genetically modified to express secondary lymphoid tissue chemokine (CCL-21/SLC) have been shown to stimulate potent antitumor responses in murine models. When injected intratumorally, CCL-21 colocalizes DC and lymphocyte effector cells at the tumor site. This may improve tumor antigen presentation and T cell activation by utilizing the tumor as an in vivo source of antigen for DC. In order to develop DC-based cancer therapies for intratumoral injection that could promote tumor antigen uptake and presentation in situ, we constructed and characterized an adenoviral vector that expresses human CCL-21 (AdCCL-21). RESULTS: Human monocyte derived DC were cultured in GM-CSF and IL-4 for 6 days. Following AdCCL-21 transduction, CCL-21 protein production was assessed by ELISA on day 8. DC transduced with AdCCL-21 at multiplicities of infection (MOIs) of 50:1 or 100:1 produced up to 210 +/- 9 ng/ml and 278 +/- 6.5 ng/ml /106 cells/48 hours, respectively. Following transduction, an immature DC phenotype was maintained and an upregulation of the costimulatory molecule, CD86 was noted. In addition, supernatant from AdCCL-21-DC caused significant chemotaxis of peripheral blood lymphocytes and mature DC. CONCLUSIONS: These studies demonstrate that AdCCL-21-DC generate functional levels of CCL-21 without adversely altering DC phenotype. These findings strengthen the rationale for further investigation of AdCCL-21-DC as a DC-based therapy in cancer treatment.

Interleukin-7 gene-modified dendritic cells reduce pulmonary tumor burden in spontaneous murine bronchoalveolar cell carcinoma.

The antitumor efficiency of dendritic cells transduced with an adenovirus vector expressing interleukin (IL)-7 (DC-AdIL-7) was evaluated in a murine model of spontaneous bronchoalveolar cell carcinoma. These transgenic mice (CC-10 TAg), expressing the SV40 large T antigen under the Clara cell promoter, develop bilateral multifocal pulmonary adenocarcinomas and die at 4 months as a result of progressive pulmonary tumor burden. Injection of DC-AdIL-7 in the axillary lymph node region (ALNR) weekly for 3 weeks led to a marked reduction in tumor burden with extensive lymphocytic infiltration of the tumors and enhanced survival. The antitumor responses were accompanied by the enhanced elaboration of interferon (IFN)-gamma and IL-12 as well as an increase in the antiangiogenic chemokines, IFN-gamma-inducible protein 10 (IP-10/CXCL10) and monokine induced by IFN-gamma (MIG/CXCL9). In contrast, production of the immunosuppressive mediators IL-10, transforming growth factor (TGF)-beta, prostaglandin E(2) (PGE(2)), and the proangiogenic modulator vascular endothelial growth factor (VEGF) decreased in response to DC-AdIL-7 treatment. Significant reduction in tumor burden in a model in which tumors develop in an organ-specific manner provides a strong rationale for further evaluation of DC-AdIL-7 in regulation of tumor immunity and its use in lung cancer genetic immunotherapy.