Optimisation of a Selection Strategy for Drug Resistance Osteosarcoma Cell Lines


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Kaan Low1,Frank Hills1,Helen Roberts1,Britta Stordal1
1Middlesex University

Abstract

Background

Osteosarcoma is the most common primary malignant bone tumour and also the second highest cause of cancer-related death in children and teenagers. Forty percent of patients will experience systemic relapse after chemotherapy, and this is likely to associated with chemotherapy drug resistance. We used a clinically-relevant comparative-selection strategy to develop novel chemo-resistant cell lines. We aim to investigate the mechanisms of resistance that arise from different exposures of cisplatin, doxorubicin and methotrexate.

Method

An acid phosphatase assay was performed to determine drug resistance. Doses of the drugs that used in the pulse selection strategy was optimised from inhibitory concentration (IC) values of cytotoxicity assay ranging from IC60to IC80.

Results

HOS-143B displays a higher level of resistance to cisplatin and methotrexate compared to MG-63 with IC50values 1.05 ±0.04mg/ml and 0.25 ±0.04mg/ml for cisplatin, and 28.23 ±2.05ng/ml and 16.85 ±0.64ng/ml for methotrexate respectively. However, HOS-143B displays a lower level of resistance to doxorubicin with IC IC50values 12.00 ±0.18nM and 25.64 ±0.68nM respectively. Interestingly, resistance to methotrexate developed quicker and at a higher level in MH-63 (marginally metastatic) compared to HOS-143B (highly metastatic). MG-63/MTXR3 displays the highest level of resistance to methotrexate with 25-fold, p=0.0069 while HOS-143B/MTXR3 shows a lower level of resistance with 2.3-fold, p=0.004. MG-63/CISR3, HOS-143B/CISR3 and HOS-143B/DOXR3 all has resistance to their respective agents (1.6-2.9 fold, p=0.0006-0.034). Interestingly, there was no significant drug resistance established in the cell lines treated with the triplet combination of cisplatin, doxorubicin and methotrexate. This suggests that cell models developed with a single drug may not reflect chemo-resistant in the clinical treatment of osteosarcoma.

Conclusion

In conclusion, the developed resistance models are valuable tools with which to study the resistance of anticancer drugs and to identify the methods to overcome resistance in osteosarcoma.