- Establishment of an adriamycin-resistant human bladder cancer cell line (T-24/ADM) and analysis of the mechanism of resistance
A human bladder cencer cell line resistant to adriamycin (ADM), T-24/ADM was establishied in vitro by exposing T-24 parent cells to a progressively higher concentration of the drug over an 18 month period. The T-24/ADM was 34.9 times more resistant to ADM than the T-24 parent. The T-24/ADM exhibited cross resistance to ADM derivatives, vinca alkaloid (vindesine, vincristine), etoposide and SN-38, but collateral sensitivity to methotrexate. The biological and biochemical characteristics of T-24/ADM were examined in terms of ADM-resistance. Although a flow cytometric analysis showed that Pglycoprotein is not expressed on the T-24/ADM cells, lower accumalation of the drug caused by decreased uptake and increaced active efflux were observed. The cellular level of glutathione-S-transferase π was 1.8-fold higher than the parent cells and the activity of nuclear extracts of DNA topoisomerase Ⅱ for T-24/ADM assayed by decatenation of kinetoplast DNA was lower, about one-half that of the T-24 parent. Confocal laser microscopy revealed the difference in intracellular distribution of ADM in T-24/ADM; in particular, the accumlation of the drug in the nucleus decreased. Additionally western blot analysis showed an enhanced expression of multidrug resistance-associated protein (MRP) in the T-24/ADM cells. This resistant cell may be used as an experimantal system to elucidate the mechanisum of ADM resistance and also as a model for developing new chemotherapeutic strategies against multi-drug resistant bladder cancer.
岡山医学会雑誌 113 (1), 1-16, 2001-04-28