Mechanistic Analysis of Taxol-induced Multidrug Resistance in an Ovarian Cancer Cell Line

Objectives: To establish a taxol-resistant cell line of human ovarian carcinoma (A2780/Taxol) and investigateits biological features.
Methods: The drug-resistant cell line (A2780/Taxol) was established by continuous stepwiseselection with increasing concentrations of Taxol. Cell morphology was assessed by microscopy and growth curveswere generated with in vitro and in vivo tumor xenograft models. With rhodamine123 (Rh123) assays, cell cycledistribution and the apoptotic rate were analyzed by flow cytometry (FCM). Drug resistance-related and signalassociated proteins, including P-gp, MRPs, caveolin-1, PKC-α, Akt, ERK1/2, were detected by Western blotting.
Results: A2780/Taxol cells were established with stable resistance to taxol. The drug resistance index (RI) was430.7. Cross-resistance to other drugs was also shown, but there was no significant change to radioresistance.Compared with parental cells, A2780/Taxol cells were significantly heteromorphous, with a significant delay inpopulation doubling time and reduced uptake of Rh123 (p < 0.01). In vivo, tumor take by A2780 cells was 80%,and tumor volume increased gradually. In contrast, with A2780/Taxol cells in xenograft models there was notumor development. FCM analysis revealed that A2780/Taxol cells had a higher percentage of G0/G1 and lowerS phase, but no changes of G2 phase and the apoptosis rate. Expression of P-gp, MRP1, MRP2, BCRP, LRP,caveolin-1, PKC-α, Phospho-ERK1/2 and Phospho-JNK protein was significantly up-regulated, while Akt andp38 MARK protein expression was not changed in A2780/Taxol cells.
Conclusion: The A2780/Taxol cell line isan ideal model to investigate the mechanism of muti-drug resistance related to overexpression of drug-resistanceassociated proteins and activation of the PKC-α/ERK (JNK) signaling pathway.