Heiko Neuss

The ubiquitin- and proteasome-dependent degradation of COX-2 is regulated by the COP9 signalosome and differentially influenced by coxibs

The cyclooxygenase-2 (COX-2) enzyme is induced upon inflammation and in neoplastic tissues. It produces prostaglandins that stimulate tumor angiogenesis and tumor growth. Therefore, destruction and/or specific inhibition of COX-2 should be an important aspect of future tumor therapy. Recently, clinical application of specific COX-2 inhibitors called coxibs became doubtfully because they produce serious renal and cardiovascular complications under long term application. The exact underlying mechanisms are poorly understood and the different effects of diverse coxibs are not explained. It has been demonstrated before that COX-2 is degraded by the ubiquitin (Ub) proteasome system (UPS). However, how ubiquitination is accomplished and regulated was unclear. An important regulator of the UPS is the COP9 signalosome (CSN), which controls the stability of many proteins. Here we show that the proteasome-dependent degradation of COX-2 in HeLa cell lysate and in HeLa cells was stimulated by curcumin, an inhibitor of CSN-associated kinases. These data suggest a function of the CSN in the degradation of COX-2. In addition, proteolysis of COX-2 was significantly accelerated by parecoxib, but not by celecoxib or rofecoxib. By density gradient centrifugation and immunoprecipitation we demonstrate that COX-2 physically interacts with the CSN. Moreover, COX-2 is associated with large complexes consisting of the CSN, cullin-RING Ub ligases and the 26S proteasome. Pulldown experiments with Flag-COX-2 revealed cullin 1 and cullin 4 as components of the large super-complexes. Cullin 1 and 4 are scaffolding proteins of Ub ligases that presumably ubiquitinate COX-2. Treatment of HeLa cells with parecoxib results in an accelerated degradation of endogenous COX-2 accompanied by an increase of COX-2-Ub conjugates. In HeLa cells parecoxib is converted to the selective COX-2 inhibitor valdecoxib. Addition of valdecoxib also stimulates COX-2 degradation in HeLa cells. We therefore conclude that valdecoxib specifically interacts with COX-2 and induces a conformation accessible for ubiquitination and degradation.

A prospective randomized trial: The influence of intraoperative application of fibrin glue after radical inguinal/iliacal lymph node dissection on postoperative morbidity

BACKGROUND Effects of intraoperative application of fibrin glue following combined radical inguinal and iliacal lymph node dissection (RILND) on the amount of postoperative lymphatic secretion are discussed controversially. To detect whether fibrin glue application results in a decreased lymphatic secretion following RILND a randomized patient blinded clinical trial was conducted. METHOD Between September 2003 and September 2006 58 patients with stage IV melanoma underwent therapeutic RILND and were randomized into two groups. 29 Patients received 4 cc fibrin glue after RILND whereas 29 patients were only irrigated with saline 0.9 percent. Postoperatively all patients received two inguinal and one iliacal closed suction drain. The main outcome criteria were the duration of drain placement in the wound. Minor criteria were the total amount of secretion and the length of hospital stay. RESULTS There was no difference between the treatment and the control group in the duration of drain placement (fibrin group: 4 days (1-27); control group 5 days (1-26); p=0.64). The total amount of fluid was 310 cc (30-6005) in the fibrin group vs. 365 cc (30-3945 cc) in the control group (p=0.9) and the length of hospital stay 10 days (3-41) (group 1) compared to 11 days (3-41) (p=0.99) were not different between both groups either. CONCLUSION Intraoperative application of 4 cc fibrin glue does not reduce the length of drain placement, drain output or hospitalisation of patients undergoing RILND with melanoma metastasis to the lymph node basin.

Analysing the serum levels of tumour markers and primary tumour data in stage III melanoma patients in correlation to the extent of lymph node metastases--a prospective study in 231 patients.

Abstract Background : Serum tumour markers correlate with biological tumour behaviour and prognosis of patients. We collected prospective data of melanoma patients in tumour stage III before radical lymph node dissection. Materials and methods : Between 2003 until 2007 we collected 231 tumour stage III patients and analysed the preoperative serum tumour markers S100 (S100 calcium binding protein), NSE (Neuron specific enolase, Enolase 2), Albumin, LDH (Lactate dehydrogenase) and CRP (C-reactive protein) and evaluated the correlation to clinical and pathological data. We divided patients into a group with only a positive sentinel lymph node (group 1; n = 109) and a second with further lymph node metastases (group 2; n = 122). Results : Patients of group 2 had a significant higher T level (p < 0.0001) and Breslow index (p < 0.0001). Patients with a higher Breslow index had a higher S100 serum level (p = 0.021). Patients of group 2 displayed a significant higher level of serum S100. The serum level of CRP correlated with increasing number of lymph node metastases. Conclusions : A higher Breslow index in tumour stage III patients seems to have an influence on lymph node metastases and on S100 serum level. Patients with more than a positive sentinel lymph node do have a higher S100 level.

Influence of postoperative fluid management on pulmonary function after esophagectomy.

Abstract Purpose : The aim of this study was to investigate the effects of a restrictive vs. a liberal postoperative fluid therapy guided by intrathoracic blood volume index (ITBVI) on hemodynamic and pulmonary function in patients undergoing elective esophagectomy. Perioperative fluid therapy may influence postoperative physiology and morbidity after esophageal surgery. Definitions of adequate infusion amounts and evident rules for a fluid therapy are missing. Methods : After esophagectomy, 22 patients were randomized either to a restrictive group (RG) with low range of ITBVI (600–800 ml/m2) or a liberal group (LG) with normal ITBVI (800–1000 ml/m2). Infusion regimen was modified twice a day according to transpulmonary thermodilution measurements until the 5th postoperative day. Primary endpoint was paO2/FIO2-ratio. Secondary endpoints were pulmonary function, fluid balance and hemodynamic as well as morbidity. Results : Demographic and surgical details did not differ between both groups. The calculated sample size was not reached. There were no postoperative differences in paO2/FIO2-ratio, ITBVI, hemodynamic parameters, or morbidity either. Cumulative fluid uptake was 4.1 liter less in the RG on the 5th postoperative day (p = 0.01), and pulmonary function was better in these patients (area under curve day 2–7 for forced vital capacity (FVC), forced expiratory volume in one second (FEV’), peak expiratory flow (PEF) each < 0.05). Conclusion : ITBVI guided restrictive infusion therapy yields a lower fluid uptake, but may not result in a difference of clinical relevant parameters. A fluid restriction after esophagectomy should always be combined with hemodynamic monitoring because additional infusions may be required.

Continuous local analgesic therapy reduces pain after radical inguinal/iliacal lymph node dissection

BackgroundTo optimize postoperative pain therapy after a radical inguinal/iliacal lymph node dissection (RILND), we investigated the influence of a continuous application of a local anaesthetic via a subfascial wound catheter in the abdominal wall in addition to a standardized systemic analgesia.Materials and methodsBetween July 2007 and December 2009, 50 patients with stage III/IV of melanoma disease received, in an observational study, a systemic analgesic therapy. Of these patients, 30 were additionally treated with a subfascial catheter. Main outcome criterion was the pain under mobilisation at the first postoperative morning registered via a visual analogue score. Minor criteria were the analgesic requirement, the specific (surgical) complications and the day of discharge.ResultsPatients treated with the subfascial catheter had significant less pain at the first postoperative morning in rest (p = 0.02) and after mobilisation (p = 0.03) without increased morbidity (p = 0.45). Less patients of the treatment group needed a supplementary analgesic medication (p = 0.01) and were able to leave hospital earlier than patients of the control group (p = 0.01).ConclusionsA subfascially placed pain catheter enhances postoperative pain therapy after RILND.

Influence of surgical complications on the level of pain after radical inguinal/iliacal lymph node dissection.

Abstract Background: We collected the data of 288 patients with malignant skin tumours. We analysed the postoperative pain assessed by a visual analogue scale (VAS) to evaluate the quality of our standard peri-operative pain therapy after a radical inguinal and iliacal lymph node dissection (RILND) as well as the influence of postoperative surgical complications on the level of pain. Materials and method: The postoperative level of pain of 85 patients with malignant skin tumours who underwent a RILND between August 2003 and December 2007 was recorded prospectively. Patients received a standardised perioperative pain therapy according to level I or II of the World Health Organisation (WHO) ladder of pain. The efficiency of our pain therapy was registered via VAS in the morning of the first three postoperative days. Results: Using our standard pain therapy, we determined a VAS < 30 in rest during the first three postoperative days, but significantly more pain (VAS median 50–30) (p < 0.001) under stress. Patients with surgical complications in the postoperative period (n = 71) had significantly more pain in the postoperative period compared to patients with a regular postoperative course (p = 0.047). Conclusions: Immediately after a RILND, an analgesic therapy according to level I or II of the WHO pain ladder does not seem to be effective enough. Postoperative surgical complications lead to a higher VAS level of pain in the postoperative period.