Establishment of three cisplatin-resistant endometrial cancer cell lines using two methods of cisplatin exposure
Upon acquiring CDDP resistance, the cells tended to become small and grow in a floating state. This tendency was especially marked when using incremental exposure method. Using the incremental exposure method, a cell line obtained by isolating and culturing only adherent cells was designated EICR-Ia, and a cell line established by culturing only floating cells was designated EICR-If. A cell line obtained by the high concentration exposure method was designated EICR-II.
Upon acquiring CDDP resistance, tumor markers such as TPA and LDH increased, while proliferative capability of the cells was lowered.
The invasion capability was diminished in EICR-If cells, but was increased in EICR-Ia and EICR-II cells.
Following exposure to CDDP, the intracellular platinum concentrations were markedly elevated in EI and EICR-If cells, whereas the increase was mild in EICR-Ia and EICR-II cells and the concentration was lower than that in parent EI cells.
Studies of drug resistance gene expression revealed increased expression of MDR1, GSTπ, and Topo-II in EICR-If cells; increased expression of GSTπ in EICR-II cells; but no expression of any of the genes in EICR-Ia cells.
Analyses of cancer- and apoptosis-related genes showed increased expressions of Bcl-2, c-Myc, p53, and ICE in EICR-If cells.
Upon acquiring CDDP resistance, sensitivity to mitomycin and adriamycin decreased, but sensitivity to etoposide and 5-fluorouracil increased.
The findings indicate that the mechanisms of CDDP resistance are different in the three cell lines.
KeywordsEndometrial cancer Cisplatin (CDDP) Multidrug resistance
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