ANTITUMOR-ACTIVITY OF THALIBLASTINE (NSC-68075) IN EXPERIMENTAL OVARIAN TUMOR-CELL LINES SENSITIVE AND RESISTANT TO CISPLATIN

Cytotoxicity of thaliblastine (thalicarpine, TBL; NSC-68075) and/or cisplatin (DDP) in DDP-sensitive (O-342) and-resistant (O-342/DDP) rat ovarian tumor cell lines was comparatively determined using the MTT assay. The 50 % inhibitory dose (ID50) of DDP was found to be 6.2-mu-M in O-342 cells and 23.4-mu-M in O-342/DDP cells, while, vice versa, the ID50 of TBL was 39.3-mu-g/ml in the sensitive line and 27.3-mu-g/ml in the resistant line. Furthermore, simultaneous exposure of cells to DDP and TBL showed a significant superiority over DDP alone in O-342 cells, as evaluated with variance analysis (P < 0.001). This enhancing effect of TBL on DDP cytotoxicity, however, was not observed in the resistant cells.