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In this study we examined the antiproliferating effect of carboplatin, which is already established in ovarian carcinomas as the first line therapy, as well as the proteasome-inhibitors bortezomib, MG-115 and the CDK-inhibitor flavopiridol using ovarian carcinoma cell lines like SKOV-3 and BG1. Cell cycle-analysis and apoptosis-assay show time- and dose-dependent antiproliferating effect for all four drugs.
Signal transduction pathways of apoptosis are potential working points in modern tumour-therapy. Exemplary proteins from both main pathways of apoptosis were selected, whose detection in western blot provides information on the potential activation of the apoptosis cascade. While both cell lines show a time- and dose-dependend induction of apoptosis via the extrinsic pathway after treatment with bortezomib, the effectiveness of flavopiridol can only be established for BG1-cells.
Apart from effects of pure substances on tumour cells potential synergies of flavopiridol and proteasome-inhibitors with carboplatin were analysed. While for BG1-cells a significant dose-dependent synergistic antiproliferating effect after incubation with both flavopridol and carboplatin was detected, the SKOV-3-cellline only showed a tendency of increasing apoptosis without any correlate in western blot analysis. After simultaneous treatment with bortezomib and carboplatin an antagonistic effect on SKOV-3-cells by means of flowcytometry as well as western blot analysis can be demonstrated. Flowcytometry detected only an additive effect of a combined application of bortezomib with carboplatin on modulation of cell cycle and induction of apoptosis in BG1-cells.
As a switchpoint of many signal transduction pathways in cells, the interaction with NFκB seems to provide a promising approach for the development of new strategies in tumour therapy. Via ELISA, we investigated the activity of the NFκB-protein in cytoplasma of ovarian cancer cell lines after incubation with carboplatin, flavopridol and proteasome inhibitors. While both single agent carboplatin as well as a combination of carboplatin with flavopiridol and proteasome-inhibitors in BG1-cells lead to increasing activity of NfĸB, only the treatment with flavopiridol showed a significant modulation for the case of SKOV-3-cells. However, the combined application of flavopiridol with carboplatin yields a significant synergistc effect.