The molecular alterations in tumour cells leading to resistance towards apoptosis induced by CD95 and TRAIL-receptors are not fully understood. We report here that the stimulation of the CD95-and TRAILresistant human pancreatic adenocarcinoma cell line PancTuI with an agonistic anti-CD95 antibody or TRAIL resulted in activation of protein kinase C and NF-kB. Inhibition of protein kinase C by GoÈ 6983 sensitized these cells to apoptotic challenges and strongly diminished activation of NF-kB by anti-CD95 and TRAIL. Similarly, inhibition of NF-kB by MG132 or by transient transfection with a dominant negative mutant of IkBa restored the responsiveness of PancTuI cells to both death ligands. In the CD95 and TRAILsensitive cell line Colo357 the induction of protein kinase C and NF-kB following activation of CD95 and TRAIL-R was very moderate compared with PancTuI cells. However, pre-incubation of these cells with PMA strongly reduced their apoptotic response to anti-CD95 and TRAIL. Taken together, we show that activation of protein kinase C operates directly in a death receptordependent manner in PancTuI cells and protect pancreatic tumour cells from anti-CD95 and TRAILmediated apoptosis by preventing the loss DCm and Cytochrome c release as well as by induction of NF-kB. Oncogene (2001) 20, 4258 ± 4269.

Inability to die by apoptosis is one of the reasons for the deregulated growth of tumour cells and the frequently observed failure of chemotherapy. In this study we thought to identify the common and functionally important characteristics responsible for the apoptosis resistance of pancreatic tumour cells. We analysed cell surface expression level of death receptors CD95 and TRAIL-R1-4 as well as the expression profile of sixteen apoptosis-relevant proteins in five pancreatic carcinoma cell lines Capan1, Colo357, PancTuI, Panc89 and Panc1. These data were evaluated in the context of sensitivity towards anti-CD95 and TRAIL-mediated apoptosis. Here we report that except for resistant Panc1 cells, which only marginally expressed CD95, all other cell lines showed comparable levels of CD95 and TRAIL receptors irrespectively of their apoptotic phenotype. Interestingly, we found that the elevated expression of FLIP, Bcl-x L and IAP in parallel with a downregulation of FADD and Bid was common for the resistant cell lines. Consequently, stable overexpression of XIAP, Bcl-x L or dominant negative FADD in sensitive cells significantly reduced the death receptor mediated apoptosis while the overexpression of Bid rendered the resistant cells sensitive.

BackgroundThe prescription of the oral anticoagulant rivaroxaban to prevent thromboembolic episodes associated with orthopaedic surgery has dramatically increased since it was introduced. Rivaroxaban is beeing prescribed although recent in-vitro studies revealed that it impaired osteoblast metabolism. In this study we analysed the effect of rivaroxaban on fracture healing in a rat femur fracture model.MethodsFemur fractures were created by a 3-point-bending device in 48 Wistar rats and subsequently stabilized by intramedullary nailing. After the surgical procedure animals were randomised into four groups. Two groups were fed with 3 mg rivaroxaban per kg body weight per day and two control groups were fed with chow only. Animals were euthanized 28 or 49 days after surgical procedure. Femurs underwent undecalcified histologic staining micro CT scanning and biomechanical testing. The statistical significance was evaluated using one-way Anova with Bonferroni correction.ResultsMicro CT-scans revealed significantly increased volume of bone tissue in the fracture zone between day 28 and 49. During the same time callus volume decreased significantly. Comparing the fracture zone of the rivaroxaban group to the control group the treated group revealed a larger callus and a marginal increase of the tissue mineral density. The torsional rigidity was not influenced by the treatment of rivaroxaban.ConclusionIn the present study we were able to demonstrate that rivaroxaban does not impair fracture healing in a rat femur fracture model. Considering the fact that low molecular weight heparins delay fracture healing significantly, rivaroxaban might be an improved alternative.

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