Holger Krebbel

Bortezomib inhibits human osteoclastogenesis.

In multiple myeloma, the overexpression of receptor activator of nuclear factor kappa B (NF-κB) ligand (RANKL) leads to the induction of NF-κB and activator protein-1 (AP-1)-related osteoclast activation and enhanced bone resorption. The purpose of this study was to examine the molecular and functional effects of proteasome inhibition in RANKL-induced osteoclastogenesis. Furthermore, we aimed to compare the outcome of proteasome versus selective NF-κB inhibition using bortezomib (PS-341) and I-κB kinase inhibitor PS-1145. Primary human osteoclasts were derived from CD14+ precursors in presence of RANKL and macrophage colony-stimulating factor (M-CSF). Both bortezomib and PS-1145 inhibited osteoclast differentiation in a dose- and time-dependent manner and furthermore, the bone resorption activity of osteoclasts. The mechanisms of action involved in early osteoclast differentiation were found to be related to the inhibition of p38 mitogen-activated protein kinase pathways, whereas the later phase of differentiation and activation occurred due to inhibition of p38, AP-1 and NF-κB activation. The AP-1 blockade contributed to significant reduction of osteoclastic vascular endothelial growth factor production. In conclusion, our data demonstrate that proteasomal inhibition should be considered as a novel therapeutic option of cancer-induced lytic bone disease.

Proteasome: an emerging target for cancer therapy.

Proteasome inhibitors represent novel anti-cancer drugs which interact with the proteasome–ubiquitin pathway. The 26S proteasome is a multicatalytic threonine protease with three distinct catalytic activities. It is responsible for intracellular protein turnover in eukaryotic cells, including the processing and degradation of short- and some long-living proteins required for regulation of various cellular functions. Subsequently, the inhibition of the proteasomal function results in stabilization and accumulation of its substrates, which notably include cyclins, cyclin-dependent kinase inhibitors, transcriptional factors, tumor suppressor proteins and proto-oncogenes. This results in confounding signals in the cell inducing cell cycle arrest and activation of apoptotic programs. Acting on transcriptional factor NF-κB, which is upregulated in some tumors undergoing chemotherapy or irradiation and downregulated by proteasome inhibition, a significant chemosensitization and consequently synergistic effects concerning the anti-tumor activity could be achieved. Bortezomib is the first proteasome inhibitor that has entered clinical trials. In multiple myeloma, both the US Food and Drug Administration and European Medicine Evaluation Agency granted approval for the use of bortezomib (Velcade) for the treatment of multiple myeloma patients who have received at least two prior therapies and have demonstrated disease progression on the last therapy. At present, other trials examine the activity in a variety of solid tumors and hematological malignancies. This paper reviews preclinical and clinical results.

Ligands of peroxisome proliferator-activated receptor γ induce apoptosis in multiple myeloma

The activation of proliferator-activated receptor &ggr; (PPAR-&ggr;) by its natural and synthetic ligands induces apoptosis in several tumor cell lines, including malignant B-lineage cells. We investigated whether treatment with pioglitazone (PGZ), rosiglitazone (RGZ) or 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) inhibited tumor cell growth in five human multiple myeloma cell lines (LP-1, U-266, RPMI-8226-S, OPM-2 and IM-9) and human bone marrow myeloma cells expressing PPAR-&ggr; protein. MTT assays revealed growth arrest induced by the natural activator of PPAR-&ggr; 15d-PGJ2 and a lower antiproliferative effect with thiazolidinediones (PGZ and RGZ) in a dose-dependent manner. Induction of apoptosis was indicated by Annexin-V staining. At a dose of 50 μM, 15d-PGJ2 led to a high rate of apoptosis in all cell lines (60–92%). Furthermore, induction of apoptosis in sorted bone marrow plasma cells from myeloma patients was detected. Thiazolidinediones comprise anti-myeloma activity in vitro and should be explored further for the treatment of multiple myeloma.

Oesophageal Doppler and calibrated pulse contour analysis are not interchangeable within a goal-directed haemodynamic algorithm in major gynaecological surgery

BACKGROUND Evidence for the benefit of an intraoperative use of a goal-directed haemodynamic management has grown. We compared the oesophageal Doppler monitor (ODM, CardioQ-ODM™) with a calibrated pulse contour analysis (PCA, PiCCO2™) with regard to assessment of stroke volume (SV) changes after volume administration within a goal-directed haemodynamic algorithm during non-cardiac surgery. METHODS The data were obtained prospectively in patients with metastatic ovarian carcinoma undergoing cytoreductive surgery. During surgery, fluid challenges were performed as indicated by the goal-directed haemodynamic algorithm guided by the ODM. Monitors were compared regarding precision and trending. Clinical characteristics associated with trending were studied by extended regression analysis. RESULTS A total of 762 fluid challenges were performed in 41 patients resulting in 1524 paired measurements. The precision of ODM and PCA was 5.7% and 6.0% (P=0.80), respectively. Polar plot analysis revealed a poor trending between ODM and PCA with an angular bias of -7.1°, radial limits of agreement of -58.1° to 43.8°, and an angular concordance rate of 67.8%. Dose of norepinephrine (NE) (scaled 0.1 µg kg(-1) min(-1)) [adjusted odds ratio (OR) 0.606 (95% confidence interval, CI: 0.404-0.910); P=0.016] and changes in mean arterial pressure (MAP) to a fluid challenge (scaled 10%) [adjusted OR 0.733 (95% CI: 0.635-0.845); P<0.001] were associated with trending between ODM and PCA, whereas there was no relation to type of i.v. solution. CONCLUSIONS Despite a similar precision, ODM and PCA were not interchangeable with regard to measuring SV changes within a goal-directed haemodynamic algorithm. A decrease in interchangeability coincided with increasing NE levels and greater changes of MAP to a fluid challenge.

Influence of goal-directed therapy with balanced crystalloid–colloid or unbalanced crystalloid solution on base excess

Objective To investigate changes in standard base excess (SBE) when administering two different infusion regimens for elective hip replacement within a goal-directed haemodynamic algorithm. Methods This prospective, double-blind, randomized, controlled study enrolled patients scheduled for primary hip replacement surgery, who were randomized to receive either an unbalanced crystalloid (chloride: 155.5 mmol/l) or a 1 : 1 mixture of a balanced crystalloid and a balanced colloid (6% w/v hydroxyethyl starch 130/0.42; chloride: 98 and 112 mmol/l, respectively). Fluid management was goal-directed to optimize stroke volume using oesophageal Doppler. Results A total of 40 patients (19 female/21 male) participated in the study. After surgery, median (25–75% percentiles) SBE was significantly lower in the unbalanced group compared with the balanced group: −2.0 mmol/l (−3.1 to −1.1) versus −0.4 mmol/l (−1.2 to 0.7), respectively. This difference was mainly due to greater plasma chloride concentrations in the unbalanced group. The amount of study medication required to reach haemodynamic stability (median 1200 ml) did not differ between the two groups. Conclusion SBE decreased in the unbalanced group without influence on fluid requirements and haemodynamic stability.