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This article is part of the supplement: Abstracts of the 16th International Charles Heidelberger Symposium on Cancer Research

Open Access Poster presentation

Indentification of cancer stem-like cells in osteosarcoma and their implications in response to chemotherapy

Áurio O Lopes1*, Sara R Neves1, Anália do Carmo2, Artur A Paiva3, Maria Botelho1 and Célia M Gomes1

Author Affiliations

1 Institute of Biophysics and Biomathematics - IBILI - FMUC, Coimbra, Portugal

2 Center for Neurosciences and Cell Biology, Coimbra, Portugal

3 Histocompatibility Centre of Coimbra - University Hospital of Coimbra, Coimbra, Portugal

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BMC Proceedings 2010, 4(Suppl 2):P41  doi:10.1186/1753-6561-4-S2-P41

The electronic version of this article is the complete one and can be found online at:

Published:24 September 2010

© 2010 Lopes et al; licensee BioMed Central Ltd.


There are growing evidences that tumors contain a subset of cells with stem like properties. These cells are referred as cancer stem cells (CSC) and are responsible for driving tumor growth and recurrence. We aimed to isolate and characterize putative CSCs in a human osteosarcoma cell line (MNNG/HOS) and to explore their role in response to chemotherapy.


CSCs were isolated using the sphere-forming assay in serum-free medium under non-adherent conditions and characterized for the expression of mesenchymal stem cell markers (CD90+, CD105+, CD73+) by flow cytometry. The chemosensitity of MNNG and CSCs to doxorubicin (DOX), cisplatin (CIS) and methotrexate (MTX) was evaluated using the MTT colorimetric assay after an incubation period of 48h. Cell cycle progression was analyzed by flow cytometry with propidiun iodide.


A subpopulation of tumor cells formed sphere-clusters in serum-free medium and were positive for MSC markers. These cells revealed to be more resistant to chemotherapy in comparison with MNNG/HOS cells. The half maximal inhibitory concentrations (IC50) of DOX (0.66 ± 0.24 μM), CIS (13.18 ± 0.09 μM) and MTX (0.05 ± 0.01 μM) were significantly higher (p < 0.05) than those in MNNG/HOS cells (DOX: 0.30 ± 0.07 μM; CIS: 8.08 ± 3.78 μM; MTX: 0.006 ± 0.001 μM). All drugs induced a G2/M cell cycle arrest in MNNG/HOS cells. In opposite, no significant changes were observed in CSC.


We have identified a subset of tumor cells with stem-like properties in OS that are relatively resistant to conventional chemotherapeutic agents. Therefore conventional drugs might not address this subset of cells that can be responsible for tumor regrowth after therapy.