Only little impact on cell cycle was observed in the less sensitive cell lines, NCEB-1 and Rec-1.Thus, the grade of cell cycle alterations directly correlated to proliferation inhibition.In the control cell lines moderate G2/M cell cycle arrest was also detected in a sensitivity-dependent manner.Bortezomib induced downregulation of CCND1 but PARP Inhibitors selleck upregulation of BCL2 and CDK inhibitor p21 RNA To further analyze the impact of bortezomib on central regulator genes of cell cycle and apopotosis, real-time RTPCR analysis of MCL cell lines and control cell lines cultured in the presence or absence of bortezomib was performed.After a 24-h exposure to bortezomib, CCND1 mRNA was downregulated in all of the MCL cell lines.This downregulation was accompanied by a decrease of EIF4E RNA expression.Upregulation of p21 RNAwas detected in four out of five MCL and in both control cell lines while p15 was upregulated in two out of the five MCL cell lines and in one of the control cell lines.In contrast to the other MCL cell lines, Hbl-2 did not express GSK3A RNA but therefore revealed an upregulation of GSK3? RNA while in all other MCL cell lines the GSK3? and GSK3A mRNA expression remained nearly unchanged.
Interestingly GSK3?RNA was downregulated in the control cell lines.AKT1 RNA was downregulated in three out of five Irinotecan MCL cell lines and in one of the control cell lines.Interestingly BCL2 RNA was upregulated in two out of four MCL cell lines and one of the control cell lines after bortezomib treatment.Bortezomib exposure did impair the RNA expression of CDK2 and CDK4 stronger than that of CDK7and CDK9.4EBP1 RNAwas downregulated in all cell lines except one.Effect of conventional cytostatic agents on MCL cells Cells were exposed to clinically established cytostatic agents, encompassing the cell phase specific antimetabolites cytarabine , fludarabine , and gemcitabine as well as the anthracyclin analogue mitoxantrone , which is known to exhibit cytotoxicity throughout the cell cycle.IC50 values at 24 h of incubation were determined using WST-1 assay.Results are listed in Table 1.Both the MCL cell line Rec-1 and the non-MCL cell line Karpas 422 were relatively resistant to all antimetabolites, with the IC50 not reached within the applied dose range.Similarly, in NCEB-1, an IC50 could not be reached for cytarabine and required IC50 doses of gemcitabine and mitoxantrone were higher than in the remainder cell lines.In contrast, fludarabine was surprisingly effective in NCEB-1.Cytotoxicity of cytarabine varied significantly between cell lines with high proliferation inhibition in Jeko-1, HBL- 2, and Jurkat, but intermediate in Granta-519.Fludarabine at concentrations of <1 ?g/ml induced cytotoxicity in all cell lines except Rec-1 and Karpas 422.