Abstract 33: In vitro functional study of Ang 2 in colorectal cancer cell line and the significance of Ang 2 expression in colorectal cancer patients
Authors: Baek Moo Jun , Jeong Dongjun , Kim Chang-Jin , Kim Tae Hyun , Kim Han J. , Ahn Tae Sung , Bae Sang Byung , Lee Sang Han 
Published: May 2015

Objectives: Angiopoietin 2 (Ang-2) is an important regulator of angiogenesis, blood vessel maturation and integrity of the vascular endothelium. The correlation between the dynamic expression of Ang-2 in tumors with regions of high angiogenic activity and a poor prognosis in many tumor types makes Ang-2 an ideal drug target. The function and mechanism of Angiopoietin 2 in colorectal cancer proliferation, invasion, metastasis and angiogenesis have not been fully elucidated to date. The aim of present study was to evaluate the biological roles of Ang-2 in the colorectal cancer cell line and to correlate the Ang-2 overexpression with the clinicopathological factors of colorectal cancers.

Methods: The biological roles of Ang-2 were investigated in LoVo colorectal cancer cell line that expresses high level of Ang-2 by knockdown Ang-2 with shRNA transfection. The functional roles of Ang-2 were evaluated by invasion assay, wound healing cell migration assay, MTT assay and tube formation assay. Moreover, Ang-2 expression was investigated by immunohistochemistry on tissue microarrays of 415 cases of colorectal cancer and the association of Ang-2 expression was examined with clinicopathologic features.

Results: The LoVo cell line knockdowned Ang-2 by shRNA revealed significant decreases of viability, invasion, migration and tube formation compared to that of control (p&lt;0.005) respectively. The Ang-2 was overexpressed in 45.8% of colorectal cancers. The overexpression of Ang-2 was significantly associated with pT (p=0.048), pN (p&lt;0.001), vascular invasions (p-=0.023), lymphatic invasions (p&lt;0.001) and TNM stages (p=0.022). Multivariate Cox regression analysis showed that the overexpression of Ang-2 in pN stage 1 and 2 were an independent prognostic factor of decreased survival [pN stage 1, HR=5.17 (95% CI: 6.36-19.59, p=0.016); pN stage 2, HR=7.01 (95% CI: 1.76-27.96, p=0.006)]. The overall survival was significantly decreased in patients of Ang-2 high expression [HR=6.78 (95% CI: 4.16-11.05, p&lt;0.001)]. The cumulative survival was significantly decreased in patients of Ang-2 high expression compared to those of Ang-2 low expression by Kaplan-Meier analysis (log rank test, p&lt;0.001).

Conclusion: The overexpression of Ang-2 is significantly associated with tumor progression rather than carcinogenesis in colorectal cancer. It can be a valuable poor prognostic marker of colorectal cancer and the Ang-2 can be used in therapeutic strategies.

Citation Format: Moo Jun Baek, Dongjun Jeong, Chang-Jin Kim, Tae Hyun Kim, Han Jo Kim, Tae Sung Ahn, Sang Byung Bae, Sang Han Lee. In vitro functional study of Ang 2 in colorectal cancer cell line and the significance of Ang 2 expression in colorectal cancer patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 33. doi:10.1158/1538-7445.AM2014-33