285

ANGPT2

angiopoietin 2;ANGPT2;angiopoietin 2

ANG-2|Tie2-ligand|angiopoietin-2|angiopoietin-2B|angiopoietin-2a

8p23.1

protein-coding

Although the incidence of breast cancer metastasis (BCM) in brain has increased significantly in triple-negative breast cancer (TNBC), the mechanisms remain elusive. Using in vivo mouse models for BCM in brain, we observed that TNBC cells crossed the blood-brain barrier (BBB), lodged in the brain microvasculature and remained adjacent to brain microvascular endothelial cells (BMECs). Breaching of the BBB in vivo by TNBCs resulted in increased BBB permeability and changes in ZO-1 and claudin-5 tight junction (TJ) protein structures. Angiopoietin-2 expression was elevated in BMECs and was correlated with BBB disruption. Secreted Ang-2 impaired TJ structures and increased BBB permeability. Treatment of mice with the neutralizing Ang-2 peptibody trebananib prevented changes in the BBB integrity and BMEC destabilization, resulting in inhibition of TNBC colonization in brain. Thus, Ang-2 is involved in initial steps of brain metastasis cascade, and inhibitors for Ang-2 may serve as potential therapeutics for brain metastasis.

OBJECTIVE: To study the expression of angiotensin-2 (Ang-2), Tie-2 and vascular endothelial growth factor receptor-2 (VEGFR-2) in colorectal cancer and analyze their relationship with the occurrence, recurrence, metastasis, angiogenesis and prognosis of colorectal cancer. METHODS: Immunohistochemistry with SP method was used to detect the expressions of Ang-2, Tie-2 and VEGFR-2 in 118 colorectal cancer, 40 adjacent normal tissue and 40 benign colorectal lesion specimens. RESULTS: The positivity rates of Ang-2, Tie-2 and VEGFR-2 in colorectal cancer tissue were 74.58%, 69.49%, and 61.02%, respectively, significantly higher than those in the adjacent normal tissues (25.00%, 17.50%, and 17.50%, P<0.05) and benign colorectal lesion tissues (35.00%, 32.50%, and 32.50%, P<0.05). The rates of two or three coexpression were significantly higher than that of a single expression in the cancer tissues (61.02% vs 15.25%). The microvascular density (MVD) of colorectal cancer tissues was 31.43-/+10.50, significantly higher than that of the adjacent normal tissues (10.61-/+3.76) and benign colorectal lesions (16.89-/+3.83) (P<0.05). The expressions of Ang-2, Tie-2, and VEGFR-2 were positively correlated with carcinoembryonic antigen (CEA) and MVD (P<0.05). The expression of Ang-2, but not Tie-2 and VEGFR-2, was positively correlated with CA199. Ang-2, Tie-2, and VEGFR-2 expressions showed significant differences between cases with tumor recurrence/metastasis and those without 5 years after radical mastectomy, and were all positively correlated with the 5-year survival rates (P<0.05). CONCLUSION: Ang-2, Tie-2 and VEGFR-2 are involved in the development, invasion, metastasis, and prognosis of colorectal cancer, and play important roles in the angiogenesis of the tumors.

BACKGROUND: Optimization of chemotherapy effectiveness in metastatic colorectal cancers (mCRC) is a major endpoint to enhance the possibility of curative intent surgery. FOLFIRI3 has shown promising results as second-line chemotherapy for mCRC patients previously exposed to oxaliplatin. The clinical efficacy of FOLFIRI3 was never determined in association with bevacizumab in non-previously treated mCRC patients. METHODS: We conducted a phase II clinical trial to characterize the response rate and toxicity profile of FOLFIRI3-bevacizumab as initial treatment for mCRC. Sixty-one patients enrolled in 3 investigation centers were treated with FOLFIRI3-bevacizumab (median of 10 cycles) followed by a maintenance therapy combining bevacizumab and capecitabine. Levels of plasma angiopoietin-2 (Ang-2) were measured by enzyme-linked immunosorbent assay at baseline. RESULTS: Overall response rate (ORR) was 66.7% (8% of complete and 58% of partial responses). The disease control rate was 91.7%. After a median time of follow-up of 46.7 months, 56 patients (92%) had progressed or died. The median progression free survival (PFS) was 12.7 months (95% confidence interval (CI) 9.7-15.8 months). The median overall survival (OS) was 24.5 months (95% CI: 10.6-38.3 months). Twenty-one patients underwent curative intent-surgery including 4 patients with disease initially classified as unresectable. Most common grade III-IV toxicities were diarrhea (15%), neutropenia (13%), asthenia (10%), and infections (4%). Hypertension-related medications needed to be increased in 3 patients. In multivariate analysis, surgery of metastases and Ang-2 levels were the only independent prognostic factors for PFS and OS. Indeed, baseline level of Ang-2 above 5 ng/mL was confirmed as an independent prognostic factor for progression free survival (HR = 0.357; 95% CI: 0.168-0.76, p = 0.005) and overall survival (HR = 0.226; 95% CI: 0.098-0.53, p = 0.0002). CONCLUSIONS: As front-line therapy, FOLFIRI-3-bevacizumab is associated with an acceptable toxicity and induced promising objective response rates. However, unfavorable clinical outcomes were observed in patients with high levels of angiopoietin-2.

OBJECTIVE: To investigate the expressions and clinical significance of Hypoxia-Inducible Factor-1alpha (HIF-1alpha) and angiopoietin-2 (Ang-2) proteins in laryngeal squamous cell carcinoma. METHOD: Immunohistochemical technique was used to detect the expressions of HIF-1alpha and Ang-2 protein in 52 laryngeal squamous cell carcinoma and 10 normal tissues. RESULT: The positive rates of HIF-1alpha and Ang-2 proteins were significantly higher in laryngeal squamous cell carcinoma than those in normal tissues (P < 0.05). The expressions of HIF-1alpha protein was related with TNM stage and lymph node metastasis (P < 0.05), but had no marked correlations with the sex, age and histological differentiation (P > 0.05). The level of Ang-2 expression was also correlated with TNM stage, lymph node metastasis and histological differentiation of laryngeal squamous cell carcinoma. But not related to the age and sex. There was positive correlations between both expressions of HIF-1alpha and Ang-2 proteins (r = 0. 333, P < 0.01). CONCLUSION: High expressions of HIF-1alpha and Ang-2 proteins in laryngeal squamous cell carcinoma may play an important role in tumor growth, invasion and metastasis.

BACKGROUND: Angiopoietins play a critical role in the angiogenesis related to tumor growth in concert with vascular endothelial growth factor (VEGF), and enhanced expression of angiopoietin-2 has been reported in lung cancer tissue. METHODS: Patients with lung cancer (n = 136) and healthy volunteers (n = 40) were enrolled. Serum angiopoietin-2 and VEGF concentrations were measured using enzyme-linked immunosorbent assay. RESULTS: Patients with lung cancer had higher serum angiopoietin-2 (2,046.3 +/- 1,171.3 pg/mL vs 1,269.8 +/- 494.1 pg/mL, p < 0.001) and VEGF (542.9 +/- 445.8 pg/mL vs 364.7 +/- 185.9 pg/mL, p < 0.05) [mean +/- SD] levels than the control group. Serum angiopoietin-2 and VEGF levels correlated with each other in patients with lung cancer (Spearman r = 0.30, p < 0.001), specifically in non-small cell lung cancer (NSCLC) [n = 110; r = 0.34; p < 0.001] but not in small cell lung cancer (n = 26). With stage progression in NSCLC, serum angiopoietin-2 levels increased, and patients with distant metastasis had higher levels than those without metastasis (p < 0.005). By contrast, serum VEGF level did not increase with stage progression, and only had a trend toward elevation in distant metastasis (p = 0.05). In NSCLC, the low angiopoietin-2 group (< 1,605.5 pg/mL) had a better overall survival compared to the high angiopoietin-2 group (> or = 1,605.5 pg/mL; p < 0.05), although this survival benefit was not maintained after controlling for stage in a multivariate analysis. The angiopoietin-2 levels were higher in NSCLC patients with postoperative recurrence than in those without. CONCLUSIONS: Our study suggests that serum angiopoietin-2 is a useful clinical marker for detecting NSCLC with distant metastasis and is of potential prognostic value.

Lymphatic metastasis constitutes a critical route of disease dissemination, which limits the prognosis of patients with pancreatic ductal adenocarcinoma (PDAC). As lymphangiogenesis has been implicated in stimulation of lymphatic metastasis by vascular endothelial growth factor-C (VEGF-C) and VEGF-D, we studied the effect of the angioregulatory growth factor angiopoietin-2 (Ang-2) on PDAC progression. Ang-2 was found to be expressed in transformed cells of human PDAC specimens, with corresponding Tie-2 receptors present on blood and lymphatic endothelium. In vitro in PDAC cells, Ang-2 was subject to autocrine/paracrine TGF-beta stimulation (2-fold induction, P=0.0106) acting on the -61- to +476-bp element of the human Ang-2 promoter. In turn, Ang-2 regulated the expression of genes involved in cell motility and tumor suppression. Orthotopic PDAC xenografts with forced expression of Ang-2, but not Ang-1, displayed increased blood and lymphatic vessel density, and an enhanced rate of lymphatic metastasis (6.7- to 9.1-fold, P<0.01), which was prevented by sequestration of Ang-2 via coexpression of soluble Tie-2. Notably, elevated circulating Ang-2 in patients with PDAC correlated with the extent of lymphatic metastasis. Furthermore, median survival was reduced from 28.4 to 7.7 mo in patients with circulating Ang-2 >/= 75th percentile (P=0.0005). These findings indicate that Ang-2 participates in the control of lymphatic metastasis, constitutes a noninvasive prognostic biomarker, and may provide an accessible therapeutic target in PDAC.