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Manfred P Lutz

Publications and source records attributed to Manfred P Lutz.

6 recordsLinked to original sources
PubMed2005

Docetaxel plus gemcitabine or docetaxel plus cisplatin in advanced pancreatic carcinoma: randomized phase II study 40984 of the European Organisation for Research and Treatment of Cancer Gastrointestinal Group.

PURPOSE: To define the efficacy and toxicity of docetaxel plus gemcitabine or docetaxel plus cisplatin for advanced pancreatic carcinoma. PATIENTS AND METHODS: Chemotherapy-naive patients with measurable disease and WHO performance status less than 2 were randomly assigned to receive 21-day cycles of gemcitabine 800 mg/m2 on days 1 and 8 plus docetaxel 85 mg/m2 on day 8 (arm A) or docetaxel 75 mg/m2 on day 1 plus cisplatin 75 mg/m2 on day 1 (arm B). Primary end points were tumor response and rate of febrile neutropenia grade. RESULTS: Of 96 randomly assigned patients (49 patients in arm A and 47 patients in arm B), 70 patients were analyzed for response (36 in arm A and 34 in arm B) and 89 patients were analyzed for safety (45 in arm A and 44 in arm B). Confirmed responses were observed in 19.4% (95% CI, 8.2% to 36.0%) of patients in arm A and 23.5% (95% CI, 10.7% to 41.2%) in arm B. In arm A, the median progression-free survival (PFS) was 3.9 months (95% CI, 3.0 to 4.7 months), median survival was 7.4 months (95% CI, 5.6 to 11.0 months), and 1-year survival was 30%. In arm B, the median PFS was 2.8 months (95% CI, 2.6 to 4.6 months), median survival was 7.1 months (95% CI, 4.8 to 8.7 months), and 1-year survival was 16%. Febrile neutropenia occurred in 9% and 16% of patients in arms A and B, respectively. CONCLUSION: Both regimens are well tolerated and show activity in advanced pancreatic carcinoma. The safety profile and survival analyses favor docetaxel plus gemcitabine for further evaluation.

Adult↗
PubMed2003

The tyrosine kinase Yes regulates actin structure and secretion during pancreatic acinar cell damage in rats.

Acinar cells require a functional apical actin web for secretion. During stimulation with supraphysiological concentrations of cholecystokinin (CCK), a condition that mimics acute pancreatitis, the actin filaments disintegrate. This leads to retention of secretory enzymes and, together with their premature activation, results in cell injury. Actin filaments are anchored through membrane-associated protein complexes that can be regulated through Src-family kinases in some model systems. Here we show that the Src-family kinases Yes and Lyn, but not Src and Fyn, are expressed in isolated pancreatic acini of Wistar rats. Upon stimulation with supramaximal secretory CCK (10(-8) M), Yes became reversibly tyrosine-phosphorylated and activated within 2 min. Immunocytochemical and subcellular fractionation studies showed reversible redistribution of Yes to the apical actin web and to the membrane fraction within 5 min. Coimmunoprecipitation demonstrated that Yes forms a complex with the focal adhesion protein Pyk2, which increased with CCK stimulation. In functional studies, inhibition of Src-kinase activity with PP2 partially reversed actin disintegration and also restored amylase secretion. We conclude that Yes participates in the regulation of the acinar cell actin, probably by interaction with Pyk2.

Actins↗
PubMed2003

Protein kinase A mediates cAMP-induced tyrosine phosphorylation of the epidermal growth factor receptor.

An increase in the intracellular cAMP concentration induces tyrosine phosphorylation of the epidermal growth factor receptor (EGFR) followed by activation of extracellular signal-regulated kinases 1/2 (ERK1/2). In this report we demonstrate that these effects of cAMP are mediated via activation of protein kinase A (PKA). Chemical inhibition of PKA suppressed forskolin-induced EGFR tyrosine phosphorylation and ERK1/2 activation in PC12 cells. Furthermore, forskolin failed to induce significant tyrosine phosphorylation of the EGFR and ERK1/2 activation in PKA-defective PC12 cells. Forskolin-induced EGFR tyrosine phosphorylation was also observed in A431 cells and in membranes isolated from these cells. Phosphoamino acid analysis indicated that the recombinant catalytic subunit of PKA elicited phosphorylation of the EGFR on both tyrosine and serine but not threonine residues in A431 membranes. Together, our data indicate that activation of PKA mediates the effects of cAMP on the EGFR and ERK1/2. While PKA may directly phosphorylate the EGFR on serine residues, PKA-induced tyrosine phosphorylation of the EGFR occurs by an indirect mechanism.

Animals↗
PubMed2002

Cyclic AMP induces transactivation of the receptors for epidermal growth factor and nerve growth factor, thereby modulating activation of MAP kinase, Akt, and neurite outgrowth in PC12 cells.

In PC12 cells, a well studied model for neuronal differentiation, an elevation in the intracellular cAMP level increases cell survival, stimulates neurite outgrowth, and causes activation of extracellular signal-regulated protein kinase 1 and 2 (ERK1/2). Here we show that an increase in the intracellular cAMP concentration induces tyrosine phosphorylation of two receptor tyrosine kinases, i.e. the epidermal growth factor (EGF) receptor and the high affinity receptor for nerve growth factor (NGF), also termed Trk(A). cAMP-induced tyrosine phosphorylation of the EGF receptor is rapid and correlates with ERK1/2 activation. It occurs also in Panc-1, but not in human mesangial cells. cAMP-induced tyrosine phosphorylation of the NGF receptor is slower and correlates with Akt activation. Inhibition of EGF receptor tyrosine phosphorylation, but not of the NGF receptor, reduces cAMP-induced neurite outgrowth. Expression of dominant-negative Akt does not abolish cAMP-induced survival in serum-free media, but increases cAMP-induced ERK1/2 activation and neurite outgrowth. Together, our results demonstrate that cAMP induces dual signaling in PC12 cells: transactivation of the EGF receptor triggering the ERK1/2 pathway and neurite outgrowth; and transactivation of the NGF receptor promoting Akt activation and thereby modulating ERK1/2 activation and neurite outgrowth.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2002

Caspase 8-mediated cleavage of plectin precedes F-actin breakdown in acinar cells during pancreatitis.

Pancreatic acinar cells depend on the integrity of the cytoskeleton for regulated secretion. Stimulation of isolated rat pancreatic acini with the secretagogue CCK serves as a model for human acute edematous pancreatitis. It induces the breakdown of the actin filament system (F-actin) with the consecutive inhibition of secretion and premature activation of digestive enzymes. However, the mechanisms that regulate F-actin breakdown are largely unknown. Plectin is a versatile cytolinker protein regulating F-actin dynamics in fibroblasts. It was recently demonstrated that plectin is a substrate of caspase 8. In pancreatic acinar cells, plectin strongly colocalizes with apical and basolateral F-actin. Supramaximal secretory stimulation of acini with CCK leads to a rapid redistribution and activation of caspase 8, followed by degradation of plectin that in turn precedes the F-actin breakdown. Inhibition of caspase 8 before CCK hyperstimulation prevents plectin cleavage, stabilizes F-actin morphology, and reverses the inhibition of secretion. Thus we propose that the caspase 8-mediated degradation of plectin represents a critical biochemical event during CCK-induced secretory blockade and cell injury.

Actins↗