Abstract LB-257: c-Met: a new cancer stem cell marker and therapeutic target for pancreatic cancer

Abstract

Abstract Pancreatic adenocarcinoma is a highly aggressive disease which is usually diagnosed in an advanced state and for which there are little/no effective therapies. The growth of many cancers depends on a subpopulation of self-renewing cells, termed cancer stem cells (CSC). We have previously identified such a CSC population in human pancreatic cancers which possess the cell surface marker phenotype CD44+CD24+ESA+. C-Met, a member of the receptor tyrosine kinases (RTKs) family and receptor for the hepatocyte growth factor (HGF) ligand, has been recently described as a marker of normal mouse pancreatic stem/progenitor cells. We hypothesized that c-Met may function as a cell surface marker and therapeutic target for human pancreatic CSCs. Studies were performed in low passage primary human pancreatic adenocarcinoma xenografts (n = 3) established in NOD-SCID mice. Self-renewal capacity of c-Methigh pancreatic cancer cells was assessed using in vitro sphere assays and in vivo tumorigenicity of c-Methigh pancreatic cancer cells was evaluated by cell implantation in NOD/SCID mice. In vitro studies demonstrated that c-Methigh cells formed spheres in non-adherent cultures, while c-Met− cells did not. Use of the c-Met inhibitor XL184 or c-Met knockdown with shRNA significantly inhibited tumor sphere formation. Pancreatic cancer cells expressing high c-Met had increased tumorigenic potential in vivo and cells expressing both CD44 and c-Methigh, representing 0.5-5% of pancreatic cancer cells, demonstrated the highest tumorigenic potential of all populations studied to date. C-Methigh CD44+ expressing pancreatic cancer cells demonstrated the capacity for self-renewal and production of differentiated progeny, properties that define CSCs. Further, c-Met inhibition of established primary human pancreatic tumors in NOD/SCID mice significantly inhibited tumor growth and depleted the pancreatic CSC population, when used alone or in combination with gemcitabine. Inhibition of c-Met also prevented the developmental of metastases using an intracardiac injection model. In this report, we define c-Met as a new marker for pancreatic CSC and define c-MethighCD44+ cells as a highly tumorigenic pancreatic CSC population. Our data also indicate that targeting c-Met may be useful in eradicating a CSC population and inhibiting the development of metastases. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-257.