Abstract 2858: Angiopoietin-like protein 2 as a novel serum biomarker for diagnosis and prognosis in patients with colorectal cancer

Abstract

Abstract Background: Inflammation plays a role in the carcinogenesis of sporadic colorectal cancer (CRC), and this can be supported by several evidences showing that effectiveness of nonsteroidal anti-inflammatory drugs as chemopreventive agents for CRC. Angiopoietin-like protein 2 (ANGPTL2) is known to act as a causative mediator of chronic inflammation and inflammatory carcinogenesis. However, the biological role and clinical significance of ANGPTL2 expression remains poorly understood in human cancer. We investigated the functional roles of ANGPTL2 in vitro and evaluated the clinical significance of ANGPTL2 expression in both primary tumor and matched serum in patients with CRC. Methods: ANGPTL2 gene knockdown by siRNA transfection was performed to evaluate ANGPTL2 function in CRC cancer cell line (sw480). Next, we examined ANGPTL2 expression in CRC tissues (n=194) to evaluate the association between its expression and clinicopathological findings by immunohistochemistry (IHC). Finally, we screened serum ANGPTL2 levels from 32 CRC (16 Stage I and 16 Stage IV) and 24 normal controls (NC), and validated its levels using 194 serum samples from CRC and 48 from NC to evaluate its utility as a biomarker by ELISA. Results: Knockdown of ANGPTL2 resulted in significantly inhibition of cell proliferation, migration, invasion, and resistance to anoikis in vitro. ANGPTL2 overexpressed in CRC tissues compared to normal colonic mucosa and high ANGPTL2 expression was associated with advanced T stage (p<0.01), lymphatic metastasis (p=0.04) and hepatic metastasis (p=0.04) in CRC patients. Next, we screened serum ANGPTL2 levels in CRC patients and NC, revealing that its levels in CRC patients were significantly higher than that in NC (p<0.01), and differentiated CRC patients from NC with high accuracy (AUC=0.837). Validation step also indicated that serum ANGPTL2 levels in CRC patients were significantly higher compared to NC (p<0.0001), had a promising AUC (0.885) with high sensitivity and specificity to distinguish CRC patients from NC. Serum ANGPTL2 levels also discriminated early CRC patients (stage I) from NC (AUC=0.79). High serum ANGPTL2 was significantly associated with tumor progression such as larger tumor size (p=0.03), undifferentiated adenocarcinoma (p=0.03), advanced T stage (p<0.01), peritoneal metastasis (p<0.01) in CRC. Kaplan-Meier curves revealed that high serum ANGPTL2 was significantly associated with poor disease free survival (p=0.01) and overall survival (p=0.03) in CRC. Intriguingly, ANGPTL2 levels in serum from CRC patients closely correlated with IHC scores of ANGPTL2 expression in matched CRC tissues (r=0.14, p=0.03). Conclusion: Our study first reports that overexpression of ANGPTL2 in CRC cells increased malignant potential and metastasis. Serum ANGPTL2, which might be derived from primary CRC tumor, was a novel biomarker for diagnosis and prognosis in patients with CRC. Citation Format: Takahito Kitajima, Yuji Toiyama, Tadanobu Shimura, Shozo Ide, Hiroki Imaoka, Satoru Kondo, Mikio Kawamura, Yoshinaga Okugawa, Aya Kawamoto, Junichiro Hiro, Susumu Saigusa, Masaki Ohi, Koji Tanaka, Yasuhiro Inoue, Yasuhiko Mohri, Sekido Yoshitaka, Masato Kusunoki. Angiopoietin-like protein 2 as a novel serum biomarker for diagnosis and prognosis in patients with colorectal cancer. [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 2858. doi:10.1158/1538-7445.AM2014-2858