Establishment and Characterization of Multi-Drug Resistant p53-Negative Osteosarcoma SaOS-2 Subline

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Osteosarcoma (OS) is a primary bone cancer with limited treatment options.
• Acquired chemoresistance significantly hinders therapeutic efficacy in OS.
• p53-negative SaOS-2 cells provide a model to study resistance mechanisms.

Purpose of the Study:

• To generate a p53-negative osteosarcoma (OS) SaOS-2 cellular subline resistant to specific chemotherapeutic agents.
• To investigate the underlying mechanisms of acquired chemoresistance in OS cells.

Main Methods:

• Stepwise doxorubicin (Dox) treatment to induce chemoresistance in SaOS-2 cells.
• Assessed drug sensitivity (IC50), cell viability, and proliferation.
• Analyzed expression of apoptotic markers, DNA repair proteins, and ABC transporters via western blotting and qPCR.
• Utilized flow cytometry to evaluate drug efflux and ABC transporter activity.
• Confirmed in vivo efficacy using xenograft models.

Main Results:

• Established a Dox-resistant OS subline with significantly increased IC50 values for Dox, vinblastine, and paclitaxel.
• Resistant cells showed reduced apoptosis and overexpression of ABCB1 (P-glycoprotein) and ABCC1 (MRP-1), leading to increased drug efflux.
• Elevated expression of DNA repair proteins (e.g., Rad51, ATM) contributed to chemoresistance.
• In vivo xenografts demonstrated Dox resistance in the generated OS subline.

Conclusions:

• Acquired chemoresistance in osteosarcoma involves multiple, simultaneously acting mechanisms at the single-cell level.
• The study highlights the complexity of secondary resistance in OS.
• Understanding these mechanisms is crucial for developing more effective cancer therapies.