Phenotypic characterization of drug resistance and tumor initiating cancer stem cells from human bone tumor osteosarcoma cell line OS-77

Zhao-Ming Ye,Wei-Xu Li,Yue Zhang,Di-Sheng Yang,Wei-Shan Cheng,Ren-Fu Quan

doi:10.3329/bjp.v9i3.19891

Abstract

The cancer stem cell theory suggest that presence of small subpopulation of cancer stem cells are the major implication in the cancer treatment and also responsible for tumor recurrence. Based on Hoechst 33342 dye exclusion technique, we have identified about 3.3% of cancer stem like side population (SP) cells from human osteosarcoma OS-77 cell line whose prevalence is significantly reduced to 0.3% after treatment with verapamil. The sphere formation assay revealed that osteosarcoma SP cells are highly capable to form tumor spheres (sarcospheres). Further by immunocytochemistry and RT-PCR, we show that OS-77 SP cells have enhanced expression of stem cell surface markers such as CD44, Nanog and ATP-binding cassette (ABC) transporter gene (ABCG2) which contributes to self-renewal and drug resistance, respectively. Our findings help to designing a novel therapeutic drug which could effectively target the cancer stem cells and prevent the tumor relapse.

Highlights

An aggressive human bone tumor in children and young adolescents is “Osteosarcoma”
This is a confirmatory test for the presence of ATP-binding cassette (ABC) transporter protein, which has shown to be involved in multi-drug resistance properties of side population (SP) cells in several solid tumors
This enhanced expression is further confirmed by reverse transcription (RT)-polymerase chain reaction (PCR) analysis, which showed that mRNA level of Nanog and Oct-3/4A, are significantly elevated in SP cells (Figure 4)

Summary

Introduction

An aggressive human bone tumor in children and young adolescents is “Osteosarcoma”. It is an eighth most common malignancy which contributed to 2.4% of all pediatric malignancies. According to the recently proposed CSC (cancer stem cell) theory, the presence of small population of tumor initiating cancer stem cells are involved in multi-drug resistance, treatment failure and tumor recurrence. These cancer stem cells are highly drug and apoptosis resistance and express stem cell surface genes such as Oct3/4A and Nanog (Wu et al, 2007; Gibbs et al, 2005). Elucidating the molecular mechanism and signaling pathways involved in cancer stem cells mediated tumorgenesis is essential to target the cancer stem cells inorder to eliminate the tumor relapse (Jordan et al, 2006; Hemmati et al, 2003; Li et al, 2007)

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Results

Conclusion