We investigated the effect of various anticancer drugs on CDDP-sensitive KB cells and CDDP-resistant KB cells (KBrc cells). The effect of CDDP and CDDP analogues on the two tumor cell lines were evaluated by in vitro cell growth curves. KBrc cells were resistant to both CDDP and CDDP analogues, which were effective against KB cells. No significant difference between KB cells and KBrc cells was observed in terms of the effect of 5FU and peplomycin.
Futhermore, to investigate the mechanism of resistance of KBrc cells to CDDP and CDDP analogues, we compared the intracellular platinum concentration of two tumor cell lines after the addition of CDDP and CDDP analogues to the cell culture. The platinum concentration in KBrc cells was much lower than in KB cells, when CDDP was added to the cell culture in concentrations of 10μg/ml and 100μg/ml. These results indicate that a difference in the intracellular platinum accumulation may be involved in the mechanism of resistance of CDDP-resistant tumor cells.
