Research Papers:
NOTCH1 activates the Wnt/β-catenin signaling pathway in colon cancer
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Abstract
Hideyuki Ishiguro1,*, Tomotaka Okubo1,*, Yoshiyuki Kuwabara1, Masahiro Kimura1, Akira Mitsui1, Nobuyoshi Sugito1, Ryo Ogawa1, Takeyasu Katada1, Tatsuya Tanaka1, Midori Shiozaki1, Koji Mizoguchi1, Yosuke Samoto1, Yoichi Matsuo1, Hiroki Takahashi1 and Shuji Takiguchi1
1Nagoya City University Graduate School of Medicine, Department of Gastroenterological Surgery, Mizuho-ku, Nagoya 467-8601, Japan
*These authors have contributed equally to this work
Correspondence to:
Hideyuki Ishiguro, email: [email protected]
Keywords: colon cancer, β-catenin, NOTCH1, NICD1, prognosis
Received: May 29, 2016 Accepted: June 27, 2017 Published: July 25, 2017
ABSTRACT
Purpose and Methods: The translocation of β-catenin/CTNNB1 to the nucleus activates Wnt signaling and cell proliferation; however, the precise mechanism underlying this phenomenon remains unknown. Previous reports have provided evidence that NOTCH1 is involved in the Wnt signaling pathway. Therefore, we sought to determine the mechanism by which NOTCH1 influences the Wnt/β-catenin pathway. We constructed a vector expressing the NOTCH1 intracellular domain (NICD1) and transfected the vector into HCT116 which has low expression of NICD1. Furthermore, inhibition of NOTCH signal pathway in SW480 which has abundant NICD1 expression, was performed by transfection of siNICD1 or DAPT, gamma secretase inhibitor, treatment. In addition, we evaluated NICD1 and β-catenin localization in colon cancer cell lines and in 189 colon cancer tissue samples and analyzed the correlation between the nuclear localization of NICD1 and the clinicopathological features of colon cancer patients.
Results: Immunohistochemical assays demonstrated that NICD1 and β-catenin exhibited a similar localization pattern in colon cancer tissues. In addition, we found that NICD1 induced the translocation of β-catenin to the nucleus and that NICD1 and β-catenin co-localized in the nucleus. Overexpression of NICD1 increased luciferase activity of Wnt signal pathway. On the other hand, reduction of NICD1 reduced luciferase activity of Wnt signaling pathway. In the 189 analyzed colon cancer cases, multivariate COX regression analysis demonstrated the independent prognostic impact of nuclear localization of NICD1(p=0.0376).
Conclusion: NOTCH1 plays a key role in the Wnt pathway and activation of NOTCH1 is associated with the translocation of β-catenin to the nucleus.
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