Establishment of cis-diamminedichloroplatinum (Ⅱ)-resistant human testicular seminoma cell line JKT/DDP and analysis of the expression of the genes related to anticancer drug-resistance associated with cytoplasmic CDDP metabolism *
Using a highly metastatic human testicular seminoma cell line, JKT-HM, a CDDP-resistant cell line, JKT/DDP, was established by long-term intermittent administration of a low dose of cis-diamminedichloroplatnium (Ⅱ) (CDDP). CDDP-resistance was investigated in vitro by comparison of the growth curves, CDDP-sensitivity, and intracellular CDDP concentrations of the established cell line, JKT/DDP, the original human seminoma cell line, JKT-1, and its highly metastatic derivative, JKT-HM. The growth curve and doubling time of JKT/DDP were not significantly different from those of JKT-1 or JKT-HM in culture without CDDP. However, in the presence of CDDP in culture, there was a significant difference in the growth curve. Morphological observations revealed segmentation of the cytoplasm and aggregation of chromatin in JKT-1 and JKT-HM. In contrast, in JKT/DDP, spindle-shaped cells showed cobblestone growth. In addition, the IC50 values of CDDP determined by the collagen gel drop embedded drug sensitivity test (CD-DST) showed JKT/DDP to be significantly more resistant to CDDP than the other two cell lines. Therefore, a CDDP-resistant cell line was established. Next, we investigated the expression of the genes (Multidrug resistance 1, MDR1 ; Multidrug resistance associated protein, MRP ; Lung resistance-related protein, LRP ; Glutathione-S-transferase π, GST- π) related to anticancer drug-resistance associated with the intracellular CDDP concentration and cytoplasmic CDDP metabolism in JKT-1, JKT-HM, and JKT/DDP. The intracellular CDDP concentration was lower in JKT/DDP than in the other two cell lines. mRNA expression of MDR1, MRP, LRP, and GST-π was investigated by a real-time PCR. The expression levels of MDR 1, MRP, and GST- π were significantly higher in JKT/DDP than in JKT-1 and JKT-HM. It was suggested that JKT/DDP acquired CDDP-resistance, and that an increased active exudation of cytoplasmic CDDP was involved in the acquisition of this CDDP-resistance. (Accepted on August 29, 2002) Kawasaki Igakkaishi 28(3) : 175-183, 2002
