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Multiple drug resistance in the human ovarian carcinoma cell line OAW42-A
1National Cell & Tissue Culture Centre/BioResearch Ireland, School of Biological Sciences, Dublin City University.
Abstract:
A new multidrug-resistant variant (OAW42-A) of a human ovarian carcinoma line has been selected by exposure to increasing concentrations of doxorubicin. The variant is resistant to doxorubicin, vincristine (but surprisingly not to colchicine), etoposide, tenoposide and also to cisplatin (a drug not usually involved in classical multidrug resistance), but not to 5-fluorouracil. Overexpression of P-glycoprotein in the resistant line was demonstrated by immunofluorescence and western blotting. Direct evidence for P-glycoprotein as a determinant of resistance was provided by transfection with a specific antisense oligonucleotide. Reversal was incomplete and this, along with the pattern of cross-resistance observed, suggests that additional mechanisms of resistance may also be involved. Substantial clonal variation in resistance exists within the cell line.
Insights
A new ovarian cancer cell line (OAW42-A) shows multidrug resistance due to P-glycoprotein overexpression. Additional resistance mechanisms may also be involved, indicating complex drug resistance patterns.
Area of Science:
- * Molecular biology and cancer research.
- * Drug resistance mechanisms in human carcinoma.
- * Biochemistry and cell biology of drug efflux pumps.
Background:
- * Multidrug resistance (MDR) is a major challenge in cancer chemotherapy, limiting treatment efficacy.
- * Ovarian carcinoma cell lines are frequently used to study MDR.
- * P-glycoprotein is a known mediator of MDR, but its role can be complex and multifactorial.
Purpose of the Study:
- * To characterize a newly selected multidrug-resistant human ovarian carcinoma cell line (OAW42-A).
- * To investigate the role of P-glycoprotein in the observed drug resistance.
- * To explore potential additional mechanisms contributing to MDR in this cell line.
Main Methods:
- * Selection of a multidrug-resistant variant (OAW42-A) through stepwise exposure to doxorubicin.
- * Assessment of drug resistance profiles against various chemotherapeutic agents.
- * Detection of P-glycoprotein overexpression using immunofluorescence and western blotting.
- * Functional validation of P-glycoprotein's role via antisense oligonucleotide transfection.
Main Results:
- * The OAW42-A variant exhibited resistance to doxorubicin, vincristine, etoposide, tenoposide, and cisplatin.
- * P-glycoprotein was significantly overexpressed in the resistant cell line.
- * Antisense oligonucleotide-mediated inhibition of P-glycoprotein partially reversed drug resistance.
- * The cross-resistance pattern and incomplete reversal suggest involvement of other resistance mechanisms.
Conclusions:
- * P-glycoprotein is a key determinant of multidrug resistance in the OAW42-A ovarian carcinoma cell line.
- * The observed drug resistance profile indicates that additional MDR mechanisms are likely operative.
- * Understanding these complex resistance mechanisms is crucial for developing more effective ovarian cancer therapies.