3-nitrotyrosine and Pancreatic-Neoplasms

The in vitro reactivity of capsanthin (1) and fucoxanthin (2) with peroxynitrite was investigated, and the reaction products produced by scavenging with peroxynitrite were analyzed. (14'Z)-Nitrocapsanthin (3) and 12-nitrocapsanthin (4) were isolated from the products of the reaction of capsanthin with peroxynitrite. Similarly, (14Z)-15-nitrofucoxanthin (5), (11Z)-11-nitrofucoxanthin (6), and (14Z,9'Z)-15-nitrofucoxanthin (7) were obtained from the reaction of peroxynitrite reaction with fucoxanthin. Capsanthin and fucoxanthin inhibited the nitration of tyrosine by peroxynitrite. Furthermore, nitrocapsanthins (3 and 4) and nitrofucoxanthins (5 and 6) exhibited an inhibitory effect on Epstein-Barr virus early antigen activation in Raji cells and an antiproliferative effect on human pancreatic carcinoma. Moreover, nitrocapsanthins (3 and 4) inhibited carcinogensis of mouse skin tumors initiated by 7,12-dimethylbenz[a]anthracene (DMBN).

Topics: Animals; Anticarcinogenic Agents; Burkitt Lymphoma; Cell Line, Tumor; Female; Free Radical Scavengers; Humans; Mice; Mice, Inbred ICR; Pancreatic Neoplasms; Papilloma; Peroxynitrous Acid; Skin Neoplasms; Tyrosine; Xanthophylls

During pancreatic tumorigenesis, the equilibrium between cell survival and cell death is altered, allowing aggressive neoplasia and resistance to radiation and chemotherapy. Local oxidative stress is one mechanism regulating programmed cell death and growth and may contribute to both tumor progression and suppression. Our recent in situ immunohistochemical studies demonstrated that levels of total nitrotyrosine, a footprint of the reactive nitrogen species peroxynitrite, are elevated in human pancreatic ductal adenocarcinomas. In this study, quantitative HPLC-EC techniques demonstrated a 21- to 97-fold increase in the overall levels of nitrotyrosine of human pancreatic tumor extracts compared to normal pancreatic extracts. Western blot analysis of human pancreatic tumor extracts showed that tyrosine nitration was restricted to a few specific proteins. Immunoprecipitation coupled with Western analysis identified c-Src tyrosine kinase as a target of both tyrosine nitration and tyrosine phosphorylation. Peroxynitrite treatment of human pancreatic carcinoma cells in vitro resulted in increased tyrosine nitration and tyrosine phosphorylation of c-Src kinase, increased (>2-fold) c-Src kinase activity, and increased association between c-Src kinase and its downstream substrate cortactin. Collectively, these observations suggest that peroxynitrite-mediated tyrosine nitration and tyrosine phosphorylation of c-Src kinase may lead to enhanced tyrosine kinase signaling observed during pancreatic ductal adenocarcinoma growth and metastasis.

Topics: Adenocarcinoma; Blotting, Western; Chromatography, High Pressure Liquid; Cortactin; Humans; Microfilament Proteins; Nitrates; Pancreatic Neoplasms; Phosphorylation; Phosphotyrosine; Precipitin Tests; Protein Conformation; Protein Folding; Proto-Oncogene Proteins pp60(c-src); Tumor Cells, Cultured; Tyrosine

Despite recognition of the devastating malignant potential of pancreatic cancer, the exact pathophysiological events contributing to tumor growth, vascular invasiveness, and hepatic metastasis remain to be elucidated.. Twelve human pancreatic adenocarcinomas were evaluated using immunohistochemical and in situ hybridization techniques for the appearance of the angiogenic and neurogenic growth factors, acidic fibroblast (FGF-1) and basic fibroblast growth factor (FGF-2), and their high-affinity receptors. Since FGF biological processes appear to be regulated by oxidant stress, tumors were examined further for the immunoappearance of inducible nitric oxide synthase (iNOS) and nitrotyrosine.. Compared with normal human pancreatic tissue, tumor specimens exhibited varying levels of enhanced staining for FGF ligands and receptors. The increased appearance of FGF-1 and FGF-2 proteins was accompanied by increased detection of messenger RNA encoding each growth factor. In addition, these pancreatic tumors demonstrated the overexpression of iNOS and immunostaining of nitrotyrosine compared with normal pancreatic tissue.. The enhanced expression of FGF and FGF receptors suggests that these polypeptide mitogens may serve as important mediators of growth and of angiogenic and metastatic responses associated with pancreatic tumors, not seen in normal pancreatic tissue. Furthermore, we provide the first indication of increased expression of iNOS and protein tyrosine nitration, thereby predicting the potential involvement of oxidant stress during development and progression of pancreatic adenocarcinoma.

Topics: Adenocarcinoma; Aged; Aged, 80 and over; Fibroblast Growth Factors; Humans; Immunohistochemistry; Nitric Oxide Synthase; Pancreatic Neoplasms; Retrospective Studies; Tyrosine