The development of chemoresistance is a major obstacle for successful anticancer therapy. Understanding the molecular mechanisms leading to chemoresistance is a rational step to improve the therapeutic efficacy of cytotoxic drugs. Since anthracyclines play an important role in cancer chemotherapy, we have generated a human ovarian tumor cell line resistant to sabarubicin (MEN 10755), the newest anthracycline molecule in clinical development. Expression of the transporter protein MRP that affected sabarubicin uptake, and a reduced DNA topoisomerase II content in A2780/saba cells was observed. Since the poisoning of DNA topoisomerase II results in DNA damage, which is a critical signal for NF-κB activation, we explored if this transcription factor has a role in the chemoresistance to anthracyclines. We showed a reduced NF-κB activation in the resistant cell line. Moreover, qualitative changes in NF-κB dimer formation between the two cell lines were observed. In agreement with the hypothesis of a role of NF-κB in mediating drug resistance, we showed that the pharmacological inhibition of NF-κB activation attenuated drug resistance in A2780/saba cells whereas it had no effect in A2780 cells. Altogether, these findings show that anthracycline resistance in A2780 cell lines is due to the coexpression of several molecular mechanisms.

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