Modulation of cisplatin sensitivity by taxol in cisplatin-sensitive and -resistant human ovarian carcinoma cell lines

Purpose: The aim of this study was to determine whether taxol can circumvent cisplatin resistance, using a KF28 cell line derived from human ovarian carcinoma and a cisplatin-resistant line, KFr13, derived from the parental cell line, KF28, and taxol-resistant cell lines, KF28_TX and KFr13_TX, derived from the respective parental counterpart. Methods: KF28 is a single-cell clone of the human ovarian carcinoma cell line KF. The cisplatin-resistant KFr13 subline was established by repeated exposure of the parent KF28 cell line to escalating doses of cisplatin. Similarly, KF28_TX and KFr13_TX were established by repeated exposure of the KF28 and KFr13 cell lines to escalating doses of taxol. A cytotoxicity assay was performed using a crystal violet staining method. Platinum and taxol accumulation were assayed by atomic absorption and reverse-phase high-performance liquid chromatography. The quantitative assay of MDR1 mRNA used polymerase chain reaction. Results: KFr13 cells were about 4.8-fold more resistant to cisplatin and about 1.8-fold more sensitive to taxol than were KF28 cells. When taxol resistance was induced in KF28 and KFr13 cells, sensitivity to cisplatin rose about 1.3- and 1.6-fold respectively. Elevation of sensitivity was correlated with platinum uptake by both KF28_TX and KFr13_TX cells. Expression of multidrug resistance (MDR1) mRNA, which was not observed in KF28 and KFr13 cells, was observed after induction of taxol resistance. Conclusions: These results may suggest rational therapeutic strategies for patients with cisplatin-resistant or refractory ovarian carcinoma. Received: 1 April 1999 / Accepted: 13 May 1999