Multidrug Resistance-1 and P-glycoprotein in Human Chondrosarcoma Cell Lines: Expression Correlates with Decreased Intracellular Doxorubicin and In Vitro Chemoresistance

Abstract

Summary:We report on two chondrosarcoma cell lines, FS and AQ, that may be used as models of multidrug resistance in chondrosarcoma. Multidrug resistance-1 expression was assayed with reverse transcriptionpolymerase chain reaction. Immunostaining for the multidrug resistance-1 product, P-glycoprotein, was performed with the monoclonal antibody C494. Intracellular levels of doxorubicin were measured by fluorescent emission at 590 nm after 1 hour of incubation with the agent and again after 1,2, and 4-hour washout periods. Chcmosensitivity was assayed by staining micropellet cultures of AQ and FS cells with fluorescein acetate before and after the cells were exposed to varying doses of doxorubicin for 48 hours. Cylotoxicity was assessed by comparison of computer-processed images before and after treatment. The FS cell line was positive for multidrug resistance-1 expression. stained heavily for P-glycoprotein, and had significantly lower intracellular levels of doxorubicin than the AQ cell line, which was negative for multidrug resistance-1 and P-glycoprotein. Chemosensitivity testing showed that the FS cell line was significantly more resistant to doxorubicin than was the AQ cell line at all doses tested. Our results show that multidrug resistance-1 expression in a human chondrosarcoma cell line results in resistance to doxorubicin in vitro.

New chondrosarcoma cell lines and mouse models to study the link between chondrogenesis and chemoresistance

“…Previous studies demonstrated that several CS cell lines overexpress efflux pumps or anti-apoptotic proteins, reducing their sensitivity to DOX or CIS. 12,13 For instance, OUMS27 or SW1353 cells in monolayer had IC50 values for these drugs between 5 and 400 mM, 13 ie 10-100 folds higher than the IC50 values calculated here. This discrepancy could be explained by the use of different cell lines, passages, culture conditions, and/or drug formulation.…”

“…High expression of multidrug resistance (MDR) pumps could be implicated to export the drugs from within the cells, and the role of ABCB1 gene product P-glycoprotein 1 (also known as MDR1) in resistance of a CS cell line to doxorubicin (DOX) has been demonstrated. 12 The low proliferation rates of CS cells may also limit the efficacy of chemotherapeutic agents, which target more specifically actively dividing cells. 9 Moreover, there is evidence that CSs overexpress several anti-apoptotic genes such as BCL-2 or Survivin (also known as BIRC5), preventing cell death induced by conventional chemotherapy.…”

The Clinical Approach Towards Chondrosarcoma

“…An additional explanation for this chemotherapy resistance may be expression of the multidrug-resistance 1 gene, Pglycoprotein, resulting in resistance to doxorubicin in vitro [76]. Moreover, the access of anticancer agents may be hampered by the large amount of extracellular matrix and the poor vascularity, implying that the agents have to diffuse over a relatively long distance in order to reach the tumor cells.…”