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Introduction: Angiopoietins and their receptor Tie-2 are, in concert with VEGF-A, key mediators in angiogenesis. This study evaluates the prognostic impact of all known human angiopoietins (Ang-1, Ang-2 and Ang-4) and their receptor Tie-2, as well as their relation to the prognostic expression of VEGF-A., Methods: 335 unselected stage I-IIIA NSCLC-patients were included and tissue samples of respective tumor cells and stroma were collected in tissue microarrays (TMAs). Immunohistochemistry (IHC) was used to semiquantitatively evaluate the expression of markers in duplicate tumor and stroma cores., Principal Findings: In univariate analyses, low tumor cell expression of Ang-4 (P = 0.046) and low stromal expressions of Ang-4 (P = 0.009) and Ang-2 (P = 0.017) were individually associated with a poor survival. In the multivariate analysis, low stromal Ang-2 (HR 1.88; CI 95% 1.15-3.08) and Ang-4 (HR 1.47, CI 95% 1.02-2.11, P = 0.04) expressions were independently associated with a poor prognosis. In patients with high tumor cell expression of Ang-2, a concomitantly high tumor VEGF-A expression mediated a dramatic survival reduction (P<0.001). In the multivariate analysis of patients with high Ang-2 expression, high tumor VEGF-A expression appeared an independent poor prognosticator (HR 6.43; CI 95% 2.46-16.8; P<0.001)., Conclusions: In tumor cells, only Ang-4 expression has prognostic impact in NSCLC. In tumor stroma, Ang-4 and Ang-2 are independently associated with survival. The prognostic impact of tumor cell VEGF-A in NSCLC appears strongly associated with a concomitantly high tumor cell expression of Ang-2.

The active stage of ulcerative colitis (UC) involves transmigration of polymorphonuclear (PMN) cells to colonic epithelia. The angiopoietin (Ang) pathway plays a role as the regulator of PMN transmigration. To clarify the role of the Ang/Tie pathway in the activation of UC, especially in cypt abscess formation, 67 tissue samples were obtained from patients with UC and ten controls without UC for immunohistochemical analysis for the expression of Ang-1, -2, or Tie-2. The epithelia of crypt abscess was strongly positive for Ang-1 and -2 for all 57 samples derived from patients with active UC, though the colorectal epithelium without crypt abscess showed minimal expression of Ang-1, -2, and Tie-2. Numerous transepithelial migrating PMN cells in crypt abscesses also expressed Tie-2. The specimens of UC patients in remission showed significantly less immunoreactivity for Ang-1, -2, or Tie-2. These findings suggest that the Ang/Tie pathway may play a role in the progression of UC.

Angioimmunoblastic T-cell lymphoma (AILT) is a malignant disease of peripheral T-cell origin that is characterized by a prominent proliferation of high endothelial venules in the lymph node. To investigate angiogenic mechanisms in AILT we measured the angiogenic mediator gene expression levels in the lymph nodes of 54 non-Hodgkin lymphoma patients, by immunostaining and quantitative reverse transcription polymerase chain reaction. Angiogenic mediators angiopoietin (Ang) 1 (ANGPT1), Ang2 (ANGPT2) and their receptor, Tie2 (TEK), vascular endothelial growth factor (VEGF; VEGFA) and its receptor, VEGFR2 (KDR), and hepatocyte growth factor (HGF) and its receptor, c-Met (MET) were all more highly expressed in AILT lymph nodes (16 cases) than in B-cell lymphomas (24 cases). Moreover, significantly higher Ang1 and Tie2 expression was detected in AILT cases with CD10-positive neoplastic T-cells by comparison with unspecified peripheral T-cell lymphoma (14 cases). Immunostaining confirmed the expression of Ang1 and VEGF by both neoplastic T-cells and follicular dendritic cells. These results suggest that the angiopoietin system may play an important role in the development of high vascularity in AILT lymph nodes. Consequently, as neoplastic T-cells and follicular dendritic cells are both increased in AILT and may represent an important source of angiogenic mediators, targeting these cells with anti-angiogenic strategies might represent a novel therapy for AILT.

Aim: To investigate the role of angiopoietin (Ang) -1, -2 and -4 and its receptors, Tie-1 and -2, in the growth and differentiation of gastrointestinal stromal tumors (GISTs)., Methods: Thirty GISTs, seventeen leiomyomas and six schwannomas were examined by immunohistochemistry in this study., Results: Ang-1, -2 and -4 proteins were expressed in the cytoplasm of tumor cells, and Tie-1 and -2 were expressed both in the cytoplasm and on the membrane of all tumors. Immunohistochemical staining revealed that 66.7% of GISTs (20 of 30), 76.5% of leiomyomas (13 of 17) and 83.3% of schwannomas (5 of 6) were positive for Ang-1. 83.3% of GISTs (25 of 30), 82.4% of leiomyomas (14 of 17) and 100% of schwannomas (6 of 6) were positive for Ang-2. 36.7% of GISTs (11 of 30), 58.8% of leiomyomas (10 of 17) and 83.3% of schwannomas (5 of 6) were positive for Ang-4. 60.0% of GISTs (18 of 30), 82.4% of leiomyomas and 100% of schwannomas (6 of 6) were positive for Tie-1. 10.0% of GISTs (3 of 30), 94.1% of leiomyomas (16 of 17) and 33.3% of schwannomas (2 of 6) were positive for Tie-2. Tie-2 expression was statistically different between GISTs and leiomyomas (P < 0.001). However, there was no correlation between expression of angiopoietin pathway components and clinical risk categories., Conclusion: Our results suggest that the angiopoietin pathway plays an important role in the differentiation of GISTs, leiomyomas and schwannomas.