Priority Research Papers:
ALDH/CD44 identifies uniquely tumorigenic cancer stem cells in salivary gland mucoepidermoid carcinomas
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April Adams1, Kristy Warner1, Alexander T. Pearson1,2, Zhaocheng Zhang1, Hong Sun Kim1, Daiki Mochizuki1, Gregory Basura3, Joseph Helman4, Andrea Mantesso1,5, Rogério M. Castilho6, Max S. Wicha2,8 and Jacques E. Nör1,3,7,8
1 Department of Restorative Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA
2 Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan, USA
3 Department of Otolaryngology, University of Michigan School of Medicine, Ann Arbor, Michigan, USA
4 Department of Oral and Maxillofacial Surgery, University of Michigan School of Medicine, Ann Arbor, Michigan, USA
5 Department of Oral Pathology, University of Sao Paulo School of Dentistry, São Paulo, Brazil, USA
6 Department Periodontics Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA
7 Department of Biomedical Engineering, University of Michigan College of Engineering, Ann Arbor, Michigan, USA
8 Comprehensive Cancer Center, University of Michigan, Ann Arbor, Michigan, USA
Jacques E. Nör, email:
Keywords: salivary gland cancer, tumorigenesis, self-renewal, multipotency, tumor initiating cells
Received: June 25, 2015 Accepted: September 04, 2015 Published: September 22, 2015
A small sub-population of cells characterized by increased tumorigenic potential, ability to self-renew and to differentiate into cells that make up the tumor bulk, has been characterized in some (but not all) tumor types. These unique cells, namedcancer stem cells, are considered drivers of tumor progression in these tumors. The purpose of this work is to understand if cancer stem cells play a functional role in the tumorigenesis of salivary gland mucoepidermoid carcinomas. Here, we investigated the expression of putative cancer stem cell markers (ALDH, CD10, CD24, CD44) in primary human mucoepidermoid carcinomas by immunofluorescence, in vitro salisphere assays, and in vivo tumorigenicity assays in immunodeficient mice. Human mucoepidermoid carcinoma cells (UM-HMC-1, UM-HMC-3A, UM-HMC-3B) sorted for high levels of ALDH activity and CD44 expression (ALDHhighCD44high) consistently formed primary and secondary salispheres in vitro, and showed enhanced tumorigenic potential in vivo (defined as time to tumor palpability, tumor growth after palpability), when compared to ALDHlowCD44low cells. Cells sorted for CD10/CD24, and CD10/CD44 showed varying trends of salisphere formation, but consistently low in vivo tumorigenic potential. And finally, cells sorted for CD44/CD24 showed inconsistent results in salisphere formation and tumorigenic potential assays when different cell lines were evaluated. Collectively, these data demonstrate that salivary gland mucoepidermoid carcinomas contain a small population of cancer stem cells with enhanced tumorigenic potential and that are characterized by high ALDH activity and CD44 expression. These results suggest that patients with mucoepidermoid carcinoma might benefit from therapies that ablate these highly tumorigenic cells.
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