Dual Roles for CXCL4 Chemokines and CXCR3 in Angiogenesis and Invasion of Pancreatic Cancer.

The CXCL4 paralog CXCL4L1 is a less studied chemokine that has been suggested to exert an antiangiogenic function. However, CXCL4L1 is also expressed in patient tumors, tumor cell lines, and murine xenografts, prompting a more detailed analysis of its role in cancer pathogenesis. We used genetic and antibody-based approaches to attenuate CXCL4L1 in models of pancreatic ductal adenocarcinoma (PDAC). Mechanisms of expression were assessed in cell coculture experiments, murine, and avian xenotransplants, including through an evaluation of CpG methylation and mutation of critical CpG residues. CXCL4L1 gene expression was increased greatly in primary and metastatic PDAC. We found that myofibroblasts triggered cues in the tumor microenvironment, which led to induction of CXCL4L1 in tumor cells. CXCL4L1 expression was also controlled by epigenetic modifications at critical CpG islands, which were mapped. CXCL4L1 inhibited angiogenesis but also affected tumor development more directly, depending on the tumor cell type. In vivo administration of an mAb against CXCL4L1 demonstrated a blockade in the growth of tumors positive for CXCR3, a critical receptor for CXCL4 ligands. Our findings define a protumorigenic role in PDAC development for endogenous CXCL4L1, which is independent of its antiangiogenic function. Cancer Res; 76(22); 6507-19. ©2016 AACR.

The therapeutic response in Gorham's syndrome to the beta-blocking agent propranolol is correlated to VEGF-A, but not to VEGF-C or FLT1 expression.

BACKGROUND: Gorham's syndrome is a rare illness of unknown etiology. It is characterized by a local proliferation of blood or lymphatic vessels that in bones leads to progressive resorption and destruction. The cause of the disease is not elucidated, and therapeutic options remain limited. CASE PRESENTATION: We report herein the case of a young female Caucasian patient aged 18 years with diffuse Gorham syndrome. In tissue specimens angiogenesis and massive lymphangiogenesis as well as the expression of vascular endothelial growth factor-A (VEGF-A) and neuropilins was observed. Lymphangiogenesis is a prominent feature of the disease and a number of lymphatic markers were found to be expressed, however only VEGF-A, but not vascular endothelial growth factor-C (VEGF-C) was found to be elevated in the circulation. Circulating levels of soluble VEGF receptor-1 were also not elevated. Furthermore, the patient responded favorably and the disease was stabilized following treatment with the beta-blocking agent Propranolol alone which acts on VEGF-A alone, but not on soluble VEGF receptor-1 levels. CONCLUSION: This suggests that the disease is dependent on VEGF-A, but on neither VEGF-C, the major driver of lymphangiogenesis, nor FLT1. Furthermore, Propranolol acts on VEGF-A but not FLT1 expression.

A Central Role for JNK/AP-1 Pathway in the Pro-Oxidant Effect of Pyrrolidine Dithiocarbamate through Superoxide Dismutase 1 Gene Repression and Reactive Oxygen Species Generation in Hematopoietic Human Cancer Cell Line U937.

Pyrrolidine dithiocarbamate (PDTC) known as antioxidant and specific inhibitor of NF-κB was also described as pro-oxidant by inducing cell death and reactive oxygen species (ROS) accumulation in cancer. However, the mechanism by which PDTC indices its pro-oxidant effect is unknown. Therefore, we aimed to evaluate the effect of PDTC on the human Cu/Zn superoxide dismutase 1 (SOD1) gene transcription in hematopoietic human cancer cell line U937. We herein show for the first time that PDTC decreases SOD1 transcripts, protein and promoter activity. Furthermore, SOD1 repression by PDTC was associated with an increase in oxidative stress as evidenced by ROS production. Electrophoretic mobility-shift assays (EMSA) show that PDTC increased binding of activating protein-1 (AP-1) in dose dependent-manner suggesting that the MAPkinase up-stream of AP-1 is involved. Ectopic NF-κB p65 subunit overexpression had no effect on SOD1 transcription. In contrast, in the presence of JNK inhibitor (SP600125), p65 induced a marked increase of SOD1 promoter, suggesting that JNK pathway is up-stream of NF-κB signaling and controls negatively its activity. Indeed, using JNK deficient cells, PDTC effect was not observed nether on SOD1 transcription or enzymatic activity, nor on ROS production. Finally, PDTC represses SOD1 in U937 cells through JNK/c-Jun phosphorylation. Taken together, these results suggest that PDTC acts as pro-oxidant compound in JNK/AP-1 dependent-manner by repressing the superoxide dismutase 1 gene leading to intracellular ROS accumulation.

Granulocyte-macrophage colony stimulating factor is anabolic and interleukin-1beta is catabolic for rat articular chondrocytes.

OBJECTIVE: To study the effects of GM-CSF and IL-1beta, both implicated in tissue damage in arthritis, on articular chondrocyte proliferation and metabolism, and to explore their agonist/antagonist effects. METHODS: Chondrocytes were obtained from 1-month-old rats. First-passage monolayers were incubated for 24 h with or without GM-CSF and/or IL-1beta, and labeled with 3H-thymidine, 35S-SO4 and 14C-proline. Proteoglycan and collagen synthesis were analyzed by liquid chromatography and SDS-PAGE. Gene expression was measured by RT-PCR. RESULTS: IL-1beta exerts potent, and GM-CSF weak, inhibitory effects on DNA synthesis. GM-CSF strongly stimulates, and IL-1beta inhibits, proteoglycan and collagen synthesis. IL-1beta suppresses the effect of GM-CSF, and increases the release of radioactive molecules from pre-labeled cartilage fragments; GM-CSF decreases the IL-1beta-induced effect. Interestingly, both cytokines induce the expression of each other's gene. CONCLUSIONS: IL-1beta appears to be a catabolic and anti-anabolic agent for chondrocytes, whereas GM-CSF is mainly anabolic, and blocks the IL-1beta-induced catabolic effect. It is postulated that both agents are implicated in inflammation: IL-1beta promotes tissue catabolism and destruction, whereas GM-CSF enhances tissue reconstruction.

Reactive oxygen species and superoxide dismutases: role in joint diseases.

Reactive oxygen species (ROS) are produced in many normal and abnormal processes in humans, including atheroma, asthma, joint diseases, aging, and cancer. The superoxide anion O(2)(-) is the main ROS. Increased ROS production leads to tissue damage associated with inflammation. Superoxide dismutases (SODs) convert superoxide to hydrogen peroxide, which is then removed by glutathione peroxidase or catalase. Thus, SODs prevent the formation of highly aggressive ROS, such as peroxynitrite or the hydroxyl radical. Experimental models involving SOD knockout or overexpression are beginning to shed light on the pathophysiological role of SOD in humans. Although the antiinflammatory effects of exogenous native SOD (orgotein) are modest, synthetic SOD mimetics hold considerable promise for modulating the inflammatory response. In this review, we discuss new knowledge about the role of the superoxide anion and its derivates as mediators of inflammation and the role of SODs and SOD mimetics as antioxidant treatments in joint diseases such as rheumatoid arthritis, osteoarthritis, and crystal-induced arthropathies.

Tumor necrosis factor-alpha down-regulates human Cu/Zn superoxide dismutase 1 promoter via JNK/AP-1 signaling pathway.

Overexpression of Cu/Zn superoxide dismutase 1 (SOD1) in monocytes blocks reactive oxygen species-induced inhibition of cell growth and apoptosis and renders cells resistant to the toxic effect of tumor necrosis factor (TNF)-alpha, suggesting that TNF-alpha represses the SOD1 gene in these cells. We herein show that TNF-alpha decreases SOD1 mRNA, protein, and promoter activity in U937 cells. Electrophoretic mobility-shift assays (EMSA) show that TNF-alpha decreased binding of three different complexes. Ectopic Sp1 overexpression markedly increased SOD1-basal promoter activity and partially antagonized the TNF-alpha inhibitory effect. In contrast, ectopic c-Jun overexpression mimics TNF-alpha inhibitory effects and antagonizes Sp1 stimulatory effects. In agreement with these findings, EMSA shows a TNF-alpha-induced increase in AP-1 and a decrease in Sp1 DNA binding. Disruption of the C/EBP site decreases, whereas mutation in the Sp1/Egr-1 site completely abolishes DNA-binding and promoter activity. A JNK inhibitor antagonized the negative effects of TNF-alpha on SOD1 promoter activity, suggesting that JNK signaling through c-Jun protein activation is critical for the TNF-alpha-dependent SOD1 repression. A greater understanding of the mechanisms of TNF-alpha-induced SOD1 repression could facilitate the design and development of novel therapeutic drugs for inflammatory conditions.

Negative regulation of superoxide dismutase-1 promoter by thyroid hormone.

The role of thyroid hormone [L-3,5,3'-triiodothyronine (T3)] and the thyroid hormone receptor (TR) in regulating growth, development, and metabolic homeostasis is well established. It is also emerging that T3 is associated with oxidative stress through the regulation of the activity of superoxide dismutase-1 (SOD-1), a key enzyme in the metabolism of oxygen free radicals. We found that T3 reverses the activation of the SOD-1 promoter caused by the free radical generators paraquat and phorbol 12-myristate 13-acetate through the direct repression of the SOD-1 promoter by liganded TR. Conversely, the SOD-1 promoter is significantly stimulated by unliganded TRs. This regulation requires the DNA-binding domain of the TR, which is recruited to an inhibitory element between -157 and +17 of the SOD-1 promoter. TR mutations, which abolish recruitment of coactivator proteins, block repression of the SOD-1 promoter. Conversely, a mutation that inhibits corepressor binding to the TR prevents activation. Together, our findings suggest a mechanism of negative regulation in which TR binds to the SOD-1 promoter but coactivator and corepressor binding surfaces have an inverted function. This effect may be important in T3 induction of oxidative stress in thyroid hormone excess.

Method for selecting populations of rat articular chondrocytes that exhibit distinct growth and metabolic characteristics, and their responses to growth factors, PMA and vitamin D3.

Chondrocytes were released from articular cartilage fragments of 6-week-old Wistar rats by a 2-hour treatment with bacterial collagenase. The cells from one animal were seeded in a 25-cm2 culture flask at a density of 10(5) cells/cm2. After 1 h, the flask was gently shaken and the medium, containing nonadherent cells, was transferred to a new flask. The attached cells were incubated with 5 ml of fresh medium. This procedure was repeated after 3, 24, 48 and 96 h. Resulting cell populations were then analyzed. The earlier cells attached, the more rapidly they proliferated, and the less collagen and proteoglycan (PG) they produced. The cells that attached after 24 h grew much more slowly, piled up in many areas, exhibited strong alkaline phosphatase activity and calcified extracellular matrix (ECM). Differences in deoxyribonucleic acid (DNA) and protein/PG synthesis were also observed when these cell populations were challenged with growth factors and 12-myristate 13-acetate (PMA). Pretreatment of cells for 2 h with PMA strongly enhanced DNA and PG synthesis only in cultures containing insulin-like growth factor-1. Nonselected rat articular chondrocytes (AC) subcultured at least four times as monolayers still expressed mRNA specific for aggrecan and type II collagen, suggesting conservation of the chondrogenic phenotype. In conclusion, AC of young individuals seem to be heterogeneous with respect to their capacity to proliferate and synthesize ECM. By selecting and expanding in vitro the appropriate cell population, this method could be potentially useful for studies aimed at repairing damaged cartilage.

Vitamin D inhibits Fas ligand-induced apoptosis in human osteoblasts by regulating components of both the mitochondrial and Fas-related pathways.

Apoptosis plays an important role in the regulation of bone turnover. Previously, we showed that 1,25(OH)2D3, the active form of vitamin D, may increase osteoblast survival by inhibiting apoptosis induced by serum deprivation. Human osteoblasts express the Fas receptor on their surface and its interaction with Fas ligand has been closely associated with human osteoblast apoptosis. To investigate the mechanism of 1,25(OH)2D3 inhibition of apoptosis in osteoblasts isolated from human calvaria, cells were exposed to Fas antibody. Visualization of apoptotic cells using annexin V revealed a significant decrease in apoptosis at 48 h in the presence of 1,25(OH)2D3 (14 +/- 4%, P < 0.04) compared with non-treated cells (52 +/- 4%). Furthermore, flow cytometric analysis of TUNEL-labeled osteoblasts showed a significant decrease in apoptotic cells in 1,25(OH)2D3-treated cultures (12 +/- 2%) at 48 h compared with non-treated cultures (44 +/- 3%, P < 0.04). Additionally, cells treated with 1,25(OH)2D3 survived longer as found by MTS analysis. To further explore the mechanism of 1,25(OH)2D3-mediated inhibition of apoptosis, we examined the changes in activation of death domain proteins, cleavage of caspases and mitochondrial regulators of apoptosis by Western blot analysis. A significant inhibition of caspase-8 cleavage and activity in 1,25(OH)2D3-treated cells was observed in conjunction with a decrease in the expression of the proapoptotic protein Bax with a significant increase in the expression of antiapoptotic protein Bcl-2. Furthermore, the levels of p21Cip1/WAF1, which inhibits the cleavage of caspase-8, was found to be highly induced in 1,25(OH)2D3-treated cells. In summary, these results demonstrate that the anti-apoptotic effect of 1,25(OH)2D3 in human osteoblasts after the activation of Fas-ligand is mediated by the regulation of components of both the mitochondrial and Fas-related pathways.

Estradiol represses human T-cell leukemia virus type 1 Tax activation of tumor necrosis factor-alpha gene transcription.

Adult T-cell leukemia is caused by human T-cell leukemia virus type I (HTLV-I). The HTLV-I Tax protein is essential for clinical manifestations because it activates viral and cellular gene transcription. Tax enhances production of tumor necrosis factor-alpha (TNF-alpha), which may lead to bone and joint destruction. Because estrogens might prevent osteoporosis by repressing TNF-alpha gene transcription, we investigated whether estrogens inhibit the transcriptional effects of Tax on the TNF-alpha promoter. Tax activated the -1044, -163, and -125 TNF-alpha promoters by 9-25-fold but not the -82 promoter, demonstrating that Tax activation requires the -125 to -82 region, known as the TNF response element (TNF-RE). Three copies of the TNF-RE upstream of the minimal thymidine kinase promoter conferred a similar magnitude of activation by Tax. We demonstrated that c-Jun, NFkappaB, p50, and p65 interact with and activate the TNF-RE by using mutational analysis of the TNF-RE, Tax mutants that selectively activate NFkappaB or the cAMP-response element binding protein/activating transcription factor pathway, and gel shift assays with nuclear extracts. Estradiol markedly repressed Tax-activated transcription of the TNF-alpha gene with estrogen receptor (ER) alpha or beta. Nuclear extracts from U2OS cells stably transfected with ER(alpha) demonstrated that ERs interact with the TNF-RE. Our studies provide evidence that ERs repress Tax-activated TNF-alpha transcription by interacting with a c-Jun and NFkappaB platform on the TNF-RE. Estrogens may ameliorate bone and inflammatory joint diseases in patients infected with HTLV-I by repressing transcription of the TNF-alpha gene.