20P - Verification of mechanism that CSC markers are implicated in poor prognosis for pancreatic ductal adenocarcinoma

Date 17 December 2016
Event ESMO Asia 2016 Congress
Session Poster lunch
Topics Cancer biology
Pancreatic Cancer
Presenter Kota Arima
Citation Annals of Oncology (2016) 27 (suppl_9): ix1-ix8. 10.1093/annonc/mdw573
Authors K. Arima1, T. Ishimoto1, M. Ohmuraya2, H. Okabe1, Y. Kitano1, K. Yamamura1, T. Kaida1, S. Nakagawa1, K. Imai1, D. Hashimoto1, A. Chikamoto1, Y. Yamashita1, H. Baba1
  • 1Department Of Gastroenterology, Kumamoto University, 860-8556 - Kumamoto/JP
  • 2Department Of Genetics, Hyogo College of Medicine, 663-8501 - Nishinomiya/JP

Abstract

Background

Cancer stem cells (CSCs) refer to a subset of tumor cells that have self-renewal ability and generate plenty of non-CSC cells that comprise a tumor. Aldehyde dehydrogenase 1 (ALDH1), c-Met, and CD44 have been identified as CSC markers in pancreatic ductal adenocarcinoma (PDAC). On the other hand, prostaglandin E2 (PGE2) is one of metabolites in arachidonate cascade and is implicated in the expansion of hematopoietic and tissue stem cell fraction. The aim of this study is to single out the most important CSC marker and elucidate the functional role of PGE2 for CSC expansion in PDAC.

Methods

Three CSC markers (ALDH1, CD44, and c-Met) expression was examined by immunohistochemistry in 121 primary surgical specimens of PDAC and analyzed a relationship with clinicopathological factors and clinical outcomes. The clonogenic growth potential of CSC marker-positive PDAC cells was assessed in vitro by growth assays and sphere formation assays. We next investigated the expression of CSC markers and self-renewal related genes in PDAC cell lines with PGE2 or 15-PGDH inhibitor treatment. We further conducted functional experiments using siRNA to identify the critical molecule in PDAC progression.

Results

A high level of ALDH1 expression was detected in 63 of the 121 cases, and was significantly associated with large tumor size and poor prognosis in PDAC patients. On the other hand, CD44 and c-Met expression were not associated with the prognosis. Among CSC markers, the expression of ALDH1 was significantly increased by PGE2 treatment in PDAC cells. By suppressing ALDH1 expression by siRNA, growth and sphere formation potential were inhibited in ALDH1 high-expressing PDAC cells. In contrast, the expression of ALDH1 was remarkably increased by PGE2 or 15-PGDH inhibitor treatment in PDAC cells. Finally, we found that Nanog was a down-stream molecule of PGE2-ALDH1 signaling and played crucial roles for PDAC cell expansion.

Conclusions

Our results demonstrated that PGE2 positively regulated ALDH1 expression, and the growth and sphere formation potential were promoted by increasing ALDH1 expression, resulting in poor prognosis of PDAC patients. Inhibiting PGE2-ALDH1 signaling could lead to the suppression of tumor growth in PDAC patients.

Clinical trial indentification

Legal entity responsible for the study

N/A

Funding

N/A

Disclosure

All authors have declared no conflicts of interest.